Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • ZIB Catalog
  • Articles: DFG German National Licenses  (469)
  • Opus Repository ZIB
  • 1990-1994  (469)
  • 1965-1969
  • 1900-1904
  • 1830-1839
  • 1992  (469)
  • Physical Chemistry  (227)
  • Genetics  (223)
  • Bone
Source
  • ZIB Catalog
  • Articles: DFG German National Licenses  (469)
  • Opus Repository ZIB
Material
Years
  • 1990-1994  (469)
  • 1965-1969
  • 1900-1904
  • 1830-1839
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    The genetic basis of Ro and La antibody formation in systemic lupus erythematosus (1992)
    Springer
    Rheumatology international 11 (1992), S. 243-249 
    Details
    ISSN: 1437-160X
    Keywords: Systemic lupus erythematosus ; Ro and La antibodies ; Multicenter study ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antibodies against Ro and La, including recombinant La and recombinant 60 kD-Ro, were determined by counter immunoelectrophoresis and ELISA in over 300 central European systemic lupus erythematosus (SLE) patients. The presence of both Ro and La antibodies was strongly associated with the MHC haplotype B8-C4AQ0-DR3-DQ2, the association being stronges for DR3. After exclusion of all B8-DR3 positive patients only DR3 positive patients still showed an increased incidence of Ro and La antibodies, suggesting DR3 as the primary association factor. High titers of La antibody, but not of 60 kD-Ro antibody, were also significantly associated with the presence of DR3. Other DR and DQ antigens or heterozygous DQ combinations were not significantly associated with Ro and La antibodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301501
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    MHC associations of autoantibodies against recombinant Ro and La proteins in systemic lupus erythematosus (1992)
    Springer
    Rheumatology international 12 (1992), S. 169-173 
    Details
    ISSN: 1437-160X
    Keywords: Systemic lupus erythematosus ; Genetics ; Ro and La antibodies ; Recombinant autoantigens ; MHC ; Multicenter study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antibodies against recombinant 52 kD-Ro, recombinant 60 kD-Ro and recombinant La protein were determined by ELISA in over 300 central European patients with systemic lupus erythematosus (SLE). A strong association with HLA-DR3 was found for antibodies against 52 kD-Ro and La, but not for recombinant 60 kD-Ro antibodies in the absence of antibodies against 52 kD-Ro or La. Ro/La negative SLE patients still showed an increased frequency of HLA-DR3 as compared to healthy controls. These results indicated that the preferential formation of Ro and La antibodies was not due to an unspecific stimulatory effect of HLA-DR3 but that the antibody response to certain defined proteins (52 kD-Ro and La) was influenced by MHC genes in SLE. Furthermore, the association of SLE with HLA-DR3 was independent of the effects of DR3 on the formation of 52 kD-Ro and La antibodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302148
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    L-Tyrosine-3-hydroxylase regulation in the brain: genetic aspects (1992)
    Springer
    Amino acids 3 (1992), S. 229-234 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Tyrosine hydroxylase ; Brain ; Genetics ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary L-tyrosine-3-hydroxylase (TH) is the first and rate limiting enzyme in the biosynthetic pathway of catecholamine neurotransmitters (dopamine, noradrenaline, adrenaline). Implication of dopamine (DA) in various psychopathological phenomena, such as schizophrenia, has considerably contributed to the intensity of investigation of basic biochemical regulation of TH by activation and induction. Here we consider a third, constitutional (genotypic) aspect of regulation and present evidence that differences in mesencephalic (TH/SN), striatal (TH/CS), and hypothalamic (TH/HT) TH activity between virtually isogeneic strains of mice can be explained by segregating genetic factors. Biometrical genetic analysis of progenitor strains and their crosses indicated significant additive gene effects for TH/SN, TH/CS, and TH/HT, whereas dominance effects were statistically non-significant. A monogenic model of inheritance for TH/SN and TH/CS could not be rejected, while more than one gene was indicated for TH/HT. Significant positive phenotypic correlations were found in genetically segregating populations among mesencephalic, striatal and hypothalamic TH activities. This would suggest that some common genetic factors (or linked genes) are involved in the genetic variation of all three traits. A genetic selection experiment to elucidate the cellular and biochemical mechanisms underlying these variations is in progress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805997
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Apolipoprotein genes and atherosclerosis (1992)
    Springer
    Journal of molecular medicine 70 (1992), S. 377-384 
    Details
    ISSN: 1432-1440
    Keywords: Genetics ; Apolipoproteins ; Lipoproteins ; Atherosclerosis ; Transgenic animals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to elucidate the genetic abnormalities underlying lipoprotein disorders associated with coronary heart disease susceptibility, researchers have looked for candidate genes. The studies have focused particularly on the lipoprotein transport genes. Relatively common as well as rare mutations have already been identified in several of these genes. In addition, further metabolic and genetic studies indicate that some of these loci harbor significant, but as yet undefined, genetic variation. In the next few years, it is not unreasonable to expect that all or most of the significant mutations at these loci will be catalogued. It is too early to know whether this will be sufficient to explain the genetic basis of altered lipoprotein levels or whether new loci will need to be investigated. Additional candidate gene loci might be those coding for genes involved in intracellular cholesterol metabolism, cholesterol absorption, or insulin resistance. New loci may also be revealed by the technique of reverse genetics. A more complete understanding of the genetics of atherosclerosis susceptibility will probably also entail the identification of variants at genetic loci that control both the reaction of the blood vessel wall to atherogenic lipoproteins and the thrombosis system. Investigation of the genetic basis of coronary heart disease susceptibility remains a worthwhile and lively field, with important clinical and public health ramifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235516
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Verapamil induces increased bone volume and osteopenia in female rats but has the opposite effect in male rats (1992)
    Springer
    Calcified tissue international 50 (1992), S. 524-526 
    Details
    ISSN: 1432-0827
    Keywords: Verapamil ; Bone ; Osteopenia ; Rat ; Female ; Intestinal calcium absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Verapamil inhibits the intestinal absorption of calcium (Ca) and increases serum parathyroid hormone in rats. The effects of verapamil on bone tissue after long-term treatment is, however, not well described. Adult female and male Sprague-Dawley rats received verapamil in their drinking water at a dosage of 0.075 mg/ml (low dose) or 0.75 mg/ml (high dose) for 12 weeks; control rats received only drinking water. All rats were fed a diet containing 0.1% Ca and 0.5% P. In female rats, the amount of bone ash per volume was significantly reduced from 0.742 g/ml in controls to 0.713 g/ml after low-dose treatment of verapamil, and to 0.667 g/ml following high-dose treatment (P〈0.01). The tibial length was increased from 39.7 mm in controls to 40.3 mm or to 40.7 mm after low or high doses (P〈0.01). The tibial volume increased from 0.385 ml in controls to 0.397 ml after low doses and to 0.429 ml after high doses (P〈0.01). In contrast, in male rats the amount of bone ash per volume was significantly increased from 0.578 g/ml in controls to 0.580 g/ml after low doses and to 0.620 g/ml after high doses of verapamil (P〈0.01). The tibial bone volume in males as decreased from 0.633 ml in controls to 0.641 ml after low doses and to 0.583 ml after high doses (P〈0.05). The tibial length in the males was not changed by verapamil. The intestinal absorption of Ca was reduced in male rats from 5.28 in controls to 4.03 (serosa/mucosa) after low-dose treatment and to 2.46 after high-dose treatment with verapamil (P〈0.05). In female rats, the intestinal absorption of Ca did not change after verapamil treatment. Thus, chronic treatment with verapamil in female rats induced osteopenia whereas in male rats bone growth was inhibited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582167
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Acidic phosphoproteins from bone matrix: A structural rationalization of their role in biomineralization (1992)
    Springer
    Calcified tissue international 50 (1992), S. 391-396 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Matrix ; Phosphoproteins ; Biomineralization ; Calcium ; Nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteopontin, bone sialoprotein, and bone acidic glycoprotein-75 are three acidic phosphoproteins that are isolated from the mineralized phase of bone matrix, are synthesized by osteoblastic cells, and are generally restricted in their distribution to calcified tissues. Although each is a distinct gene product, these proteins share aspartic/glutamic acid contents of 30–36% and each contains multiple phosphoryl and sialyl groups. These properties, plus a strict relationship of acidic macromolecules with cell-controlled mineralization throughout nature, suggest functions in calcium binding and nucleation of calcium hydroxyapatite crystal formation. However, direct proof for such roles is still largely indirect in nature. The purpose of this review is to present two speculative hypotheses regarding acidic phosphoprotein function. The goal was to use new sequence information along with database comparisons to develop a structural rationalization of how these proteins may function in calcium handling by bone. For example, our analysis has identified a conserved polyacidic stretch in all three phosphoproteins which we propose mediates metal binding. Also, conserved motifs were identified that are analogous with those for casein kinase II phosphorylation sites and whose number correlates well with that of phosphoryl groups/protein. A two-state conformational model of calcium binding by bone matrix acidic phosphoproteins is described which incorporates these findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296767
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Determination of histamine and polyamines in calcified tissues of mice: Contribution of mast cells and histidine decarboxylase to the amount of histamine in the bone (1992)
    Springer
    Calcified tissue international 51 (1992), S. 67-71 
    Details
    ISSN: 1432-0827
    Keywords: Histamine ; Polyamines ; Mast cells ; Histidine decarboxylase ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A simple method for determining histamine and polyamines in various tissues was devised. The method, however, could not be applied to calcified tissues, because the high concentration of Ca2+ in the extract interferes with the chromatographic separation of these amines. By treating the extracts from calcified tissues with K2CO3, we succeeded in removing the Ca2+, and the method could then be applied to determine the amines in bone tissues of mice. By using this method, we examined the contribution of mast cells and histidine decarboxylae (HDC) to the amount of histamine in the bone. The results indicate that (1) the HDC activity in the bone is the highest among the tissues of normal mice, and the histamine produced by the HDC in the bone is metabolized rapidly; (2) a major part of HDC in the bone is present in the bone marrow cells other than mast cells, and most of histamine in the bone is attributable to the histamine pooled in mast cells; (3) mast cells in the diaphysis are located largely along the endosteal lining; and (4) the method devised in this study may be useful for studying the roles of histamine (or mast cells) and polyamines in calcified tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296220
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Earlier wrist fracture: A confounding factor in distal forearm bone screening (1992)
    Springer
    Osteoporosis international 2 (1992), S. 201-204 
    Details
    ISSN: 1433-2965
    Keywords: Bone ; Distal radius ; Fracture ; Single photon absorptiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-six women aged 60, 70 or 80 years who had fractured one of their distal radii (Colles' fracture) 0 to 35 (median 10) years earlier were examined in this population-based study. Single photon measurements (SPA) were performed on both arms 1 cm and 6 cm proximal to the styloid process of the ulna. All women were questioned about earlier wrist fractures and which, if any, side had been affected. Information about the type and site of the fracture was also gathered from the hospital records. The bone mineral content (BMC) was found to be increased by almost 20% in the once-fractured radius at the distal measuring site (1 cm) when compared with the unaffected side. This difference did not seem to diminish with time. At the proximal measuring site there was no difference between the once-fractured and the non-fractured side. There was a progressive loss of bone mineral in the once-fractured arm during the first years after the fracture however. This appeared to be reversed after about 10 years to a relative gain, even though the correlation was weak. Six of the 36 women could not remember which side had been fractured and five could not remember having had such a fracture at all. Determination of osteoporosis by measuring forearm BMC with single photon densitometry is therefore of limited value in some women of the oldest age groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623927
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Epithelioid hemangioendothelioma of bone A report of two cases and review of the literature (1992)
    Springer
    Skeletal radiology 21 (1992), S. 509-513 
    Details
    ISSN: 1432-2161
    Keywords: Epithelioid hemangioendothelioma ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epithelioid hemangioendothelioma is the prototype of a group of vascular tumors characterized by epithelioid or histiocytoid endothelial cells. Epithelioid hemangioendothelioma of bone is a rare lesion that constitutes fewer than 1% of primary malignant skeletal neoplasms. We describe two cases that illustrate the spectrum of radiographic features seen with this neoplasm, and also present its appearance on magnetic resonance imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195232
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Identifying sex differences in reading disability (1992)
    Springer
    Reading and writing 4 (1992), S. 307-326 
    Details
    ISSN: 1573-0905
    Keywords: Genetics ; Reading disability ; Sex differences ; Twins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Education
    Notes: Abstract The issue of sex differences in reading disability has been of recent interest in relation to sex ratios in families with reading disabled children and to possible sex biases in referred populations. Data from a study of 570 twins are used to develop alternative definitions of reading disability that vary in the manner to which sex effects are taken into account. These definitions include discrepancies between reading quotients and IQ, the use of the regression of reading onto IQ and chronological age/reading age differences. In each case the reading and spelling disability was defined either separately for the sexes or based upon the data for the sexes combined and with and without an IQ〉90 exclusion criterion. The consequences of using the alternative definitions for prevalence, sex ratio and heritability are examined. The results demonstrate that the characteristics of reading disabled children vary with the way disability is defined. The excess of males seems to be a robust finding. Definitions that take into account differences in mean score for males and females reduce but do not eradicate the sex ratio. From the genetic analysis, there is no support for the suggestion that the genetic effect on reading is greater for females than males. It is concluded that the use of regression based procedures for identifying reading disability is desirable but that at present there is insufficient evidence to justify the adoption of separate regression procedures for the two sexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01027711
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Insulin receptor and insulin-responsive glucose transporter (GLUT 4) mutations and polymorphisms in a welsh type 2 (non-insulin-dependent) diabetic population (1992)
    Springer
    Diabetologia 35 (1992), S. 486-489 
    Details
    ISSN: 1432-0428
    Keywords: Genetics ; Type 2 (non-insulin-dependent) ; diabetes mellitus ; insulin receptor ; glucose transporters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have recently examined the exons encoding the insulin receptor tyrosine kinase domain and GLUT 4 in 30 subjects with Type 2 (non-insulin-dependent) diabetes mellitus using a molecular scanning approach. The variant sequences Val-Met985 and Lys-Glu1068 of the insulin receptor and Val-Ile383 of GLUT 4 were each separately found in three different diabetic subjects. In a study of a Welsh population, the GLUT 4383 variant was found in three of 160 diabetic and none of the 80 control subjects. In this study, the same group of Welsh Type 2 diabetic and control subjects was analysed using allele-specific oligonucleotide hybridisation, single nucleotide primer extension and allele-specific restriction digestion to ascertain the frequency of the two insulin receptor mutations. The Val-Met985 mutation was found in none of the 160 Welsh Caucasian Type 2 diabetic subjects and two of 80 control subjects. The Lys-Glu1068 mutation removes a Sty 1 site and digestion of amplified exon 18 with Sty 1 confirmed the presence of this mutation in the heterozygous state in the original subject. None of the Welsh diabetic or control subjects had the Glu1068 mutation. The discovery of a very common silent polymorphism at codon 130 of GLUT 4 allowed examination of the association of this locus with Type 2 diabetes using allele-specific oligonucleotide hybridisation in a subset of the Welsh subjects. The genotypic frequencies (homozygous wild-type and heterzygous polymorphic (poly) sequences) were not significantly different between diabetic and control subjects (Type 2 diabetic subjects: wild-type/wild-type 40%, wild-type/poly 46%, poly/poly 14%; Control subjects: wild-type/wild-type 37%0, wild-type/poly 45 %, poly/poly 18 %;p 〉 0.05). In conclusion, in a British Caucasian population the examined insulin receptor tyrosine kinase domain mutations are uncommon. Also the GLUT 4 locus does not appear to be strongly associated with Type 2 diabetes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02342449
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Repetitive loading, in vivo, of the tibia and femora of rats: Effects of a single bout of treadmill running (1992)
    Springer
    Calcified tissue international 50 (1992), S. 193-196 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Mechanical properties ; Fatigue microdamage ; Exercise
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The presence of microdamage in the tibiae and femora of rats following repetitive loading in vivo was investigated by subjecting 48 male rats, aged 12 weeks, to treadmill running (26.8 m.min-1 on 10% grade) for 0.56 hours (5,000 cycles, E1), 1.13 hours, (10,000 cycles, E2), 2.27 hours (20,000 cycles, E3), and 3.4 hours (30,000 cycles, E4) with Group C as control. Following exercise, tibiae and femora were excised and the right limbs were tested in torsion at 180°.sec-1. Transverse sections were cut from the proximal, mid- and distal diaphysis of left tibiae and femora, bulk stained in basic fuchsin, cut to 50 μm thick, and examined for the presence of microdamage. Following these periods of loading, tibiae and femora showed no evidence of microdamage initiation, as evidenced by light microscopy, or corresponding alterations in mechanical properties. It was concluded that the magnitude of loading produced by single bouts of intensive exercise, which encompassed up to 30,000 loading cycles, was insufficient to initiate fatigue microdamage in tibiae or femora of rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298800
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Competitive adsorption of magnesium and calcium ions onto synthetic and biological apatites (1992)
    Springer
    Calcified tissue international 51 (1992), S. 143-150 
    Details
    ISSN: 1432-0827
    Keywords: Adsorption ; Magnesium ; Calcium ; Apatite crystals ; Enamel ; Dentin ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Magnesium (Mg) is a conspicuous constituent of hard tissues but its possible role in biomineralization is poorly understood. It is possible that Mg2+ adsorbed onto bioapatites may contribute to the modulation of crystal growth as such inhibitory activity has been reported for synthetic apatites. The present study was undertaken to determine the adsorption isotherms of Mg ions onto synthetic apatites and biominerals in tooth and bone tissues in the presence of other ions of natural occurrence. Synthetic crystals used as adsorbents were hydroxyapatite and, as a better prototype for the biomineral, Mg-containing carbonatoapatite. Human enamel and dentin materials were obtained from extracted, caries-free, permanent teeth. Porcine dentin materials at two developmental stages were obtained from erupted deciduous and unerupted permanent teeth of a 6-month-old slaughtered piglet. Porcine bone was obtained from the cortical portion of the mandible of the same animal. All biomineral samples were pulverized and then treated by plasma ashing (deproteination) at about 60°C. Each of the powdered samples was equilibrated in solutions containing various initial concentrations of Mg2+, Ca2+, and Na+ (or K+) as nitrate salts. Following equilibration, concentrations (and activities) of magnesium and calcium ions in the experimental solution were determined. The pH values of the equilibrium solutions were in the range of 6.2–6.5. Experimental data of the Mg adsorption onto hydroxyapatite were interpreted on the basis of a Langmuir-type model for binary systems assuming competition of Mg2+ and Ca2+ for the same adsorption sites on the crystal surfaces of the apatites. According to this model, the adsorbed Mg is expressed as a function of the ionic activity ratio (Mg2+)/(Ca2+) in the equilibrium solution. The model contains two parameters, the adsorption selectivity constant Ks and the maximum number of adsorption sites N (μmol/g). The numerical values of Ks were similar for all adsorbents used (synthetic and biological) and indicated the preferential adsorption of Ca2+ probably due to spacial restrictions extending to the very surface of the crystals. The initial level of Mg2+ in the surface pool was different in the various biominerals, probably reflecting the composition of fluid in which the biominerals were formed. Whereas the surface pool of Mg of human enamel was marginal, only 5% of the total Mg, significant fractions of the total Mg in human and porcine dentins (about 20–30%), and porcine bone (about 40%) existed on the crystal surfaces. There were significant differences in the total Mg and the value of the parameter N between young (unerupted) and mature (erupted) dentin minerals. It was ascertained that the occupancy of adsorption sites by Mg ions became greater with maturation of the dentin tissues. The overall results suggest that the Mg-mineral interaction in tooth and bone tissues may be a highly tissue-specific process, presumably reflecting differences in fluid composition (particularly Ca and Mg activities) responsible for biomineralization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    An FT-IR microscopic investigation of the effects of tissue preservation on bone (1992)
    Springer
    Calcified tissue international 51 (1992), S. 72-77 
    Details
    ISSN: 1432-0827
    Keywords: Fixation ; FT-IR microscopy ; Infrared spectroscopy ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Fourier transform infrared microscopy is a powerful tool for the characterization of mineral and protein in histologic sections of bone. This study was concerned with determining whether techniques used to preserve these tissties and to prepare them for sectioning had an effect on spectral properties. The υ1, υ3 phosphate bands in the 900–1200 cm-1 spectral region were used to evaluate the structure of the apatitic mineral in fresh-frozen, ethanol-fixed, and formalin-fixed 35-day-old rat femurs; fresh-frozen and formalin-fixed 20-day-old fetal rat femurs; ground 35-day-old rat diaphyseal bone samples; and formalin-fixed, methacrylate-embedded ground diaphyseal bone. The crystallinity (crystal size and perfection) of the bone apatite was assessed by a curve-fitting analysis of the υ1, υ3 phosphate bands. Results indicate that ethanol or formalin fixation of the 35-day-old intact rat femur, and formalin fixation and embedding of the ground rat bone do not significantly alter the crystallinity of the apatite. However, formalin fixation of the fetal rat bone did alter the structure of the apatite mineral phase. In addition, evaluation of protein secondary structure in the 35-day-old rat femur from the Amide I and Amide II vibrations near 1650 and 1550 cm-1, respectively, revealed that protein conformation was altered by ethanol fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296221
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Minimal levels of serum estradiol prevent postmenopausal bone loss (1992)
    Springer
    Calcified tissue international 51 (1992), S. 340-343 
    Details
    ISSN: 1432-0827
    Keywords: Menopause ; Estrogens ; Bone ; Osteoporosis ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Biochemical parameters reflecting bone resorption [urinary calcium/creatinine (Ca/Cr) and hydroxyproline/ creatinine (OH/Cr)] were related to serum estrogens [estrone (E1) and estradiol (E2)] in 262 healthy women including 158 patients receiving estrogen replacement therapy (ERT) for at least 6 months, 49 eugonadal women, and 55 untreated postmenopausal women. A significant (P〈0.001) correlation exists between serum E2 and Ca/Cr: Ca/Cr (mg/dl)=-0.00044 E2 (pg/ml)+0.129 (n=262; r=-0.37), serum E2 and OH/Cr: (OH/Cr (mg/g)=-0.049 E2 (pg/ml)+18.76 (n=262; r=-0.36), serum E1 and Ca/Cr: Ca/Cr (mg/dl)=-0.0003 E1 (pg/ml)+0.127 (n=261; r=-0.28) but not between serum E1 and OH/Cr. Women with circulating levels of E2 between 60 and 90 pg/ml have a significant (P〈 0.01) reduction of Ca/Cr and OH/Cr when compared with those with lower levels of E2. Higher values of E2 do not provide additional benefit. We conclude that in postmenopausal women receiving an estrogen replacement therapy (ERT), a significant reduction of bone resorption is achieved when circulating levels of estradiol reach a value (60 pg/ml) corresponding to the one measured, in eugonadal women, during the last days of the early follicular phase of the menstrual cycle. We suggest that oral or percutaneous ERT should induce a minimal value of 60 pg/ml to prevent postmenopausal bone loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316876
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Effects of cyclosporin A on rat osteoblasts (ROS 17/2.8 cells) in vitro (1992)
    Springer
    Calcified tissue international 51 (1992), S. 291-297 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Osteoblast ; Cyclosporin A ; Attachment ; Proliferation ; Alkaline phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of the immunosuppressive drug cyclosporin A (CsA) were evaluated on ROS 17/2.8 cells in vitro. ROS cells were treated with CsA (0, 0.5, 1.0, 5.0 μg/ml) for 3 days with and without bovine parathyroid hormone (bPTH) (1–34) 10 nM. CsA at 0.5, 1.0, 5.0 μg/ml without PTH and at 5.0 μg/ml in the presence of PTH significantly inhibited proliferation, as determined by a tetrazolium colorimetric assay. In addition, ROS cell number was significantly reduced at 3 and 4 days with CsA (5.0 μg/ml) without affecting cell viability. Incorporation of [3H]-thymidine into DNA was significantly reduced by 3.0 and 5.0 μg/ml CsA after 12 and 24 hours exposure. Basal and 1,25-dihydroxyvitamin D3-stimulated alkaline phosphatase levels in confluent ROS cells were reduced (P〈0.05) with CsA (1.0 and 3.0 μg/ml). Pretreatment of ROS 17/2.8 cells with CsA did not alter PTH-stimulated cAMP levels or [125I]-PTHrP binding to ROS cells. CsA treatment of ROS 17/2.8 cells induced a spindle-shaped appearance with loss of attachment in confluent cultures. When ROS cells were cultured in CsA-containing media, cellular attachment at 6 and 12 hours was reduced (P〈0.05) compared with untreated ROS cells. These findings indicate that CsA was capable of inhibiting proliferation, cell number, mitogenesis, alkaline phosphatase levels, and cell attachment of ROS cells without affecting PTH binding or cAMP levels. This direct effect of CsA on osteoblasts may be important in changes of bone remodeling observed in CsA-treated humans and animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334490
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Reproducibility of lateral spine scans using dual energy X-ray absorptiometry (1992)
    Springer
    Calcified tissue international 51 (1992), S. 255-258 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Densitometry ; Dual energy X-ray absorptiometry ; Lateral spine scanning ; Reproducibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Reproducibility of lateral spine dual energy X-ray absorptiometry (LAT DEXA) scans using a Lunar DPX-L scanner was assessed in a cadaveric phantom and in patients. One hundred phantom measurements over 7 months demonstrated a longitudinal stability of 1.7% (coefficient of variation, CV). Additional scans were performed with the phantom rotated by up to 20° in each of the three orthogonal planes to assess the effects of variable patient positioning. Horizontal and vertical rotation of the spine had little effect on the estimated bone mineral density (BMD), however, axial rotation of greater than 8° led to errors in the BMD measurement. One hundred consecutive patients had two lateral scans performed within 1 month. BMD (range 0.10–1.6 g/cm2) was determined for each scan by one operator. Significant overlap from ribs and pelvis was often seen with L2 and L4 vertebrae but one vertebra (L3) could be measured in every case. Intraoperator and interoperator variability was assessed by three experienced operators, each analyzing 10 patients' scans on five separate occasions, and was found to be less than 1.1% for a single vertebra. BMD estimation of vertebral bodies and midslices by lateral DEXA scans (CV% of 3.8% and 4.6%) have a 95% confidence interval of 0.074 g/cm2 and 0.096 g/cm2, respectively for two vertebrae. This variability is due mainly to axial rotation, with operator variability, horizontal rotation, and vertical rotation having little effect on BMD estimation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334484
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Synthetic parathyroid hormone-like protein (1–74) is anabolic for bone in vivo (1992)
    Springer
    Calcified tissue international 51 (1992), S. 30-34 
    Details
    ISSN: 1432-0827
    Keywords: PTHRP ; Anabolic ; Rat ; Bone ; Potency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parathyroid hormone-related protein (PTHRP) has recently been purified from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The gene encoding PTHRP has been cloned, and based on predicted amino acid sequence, polypeptides comprising the first 36 [36Tyr(1–36) PTHRP amide] and 74 [(1–74)PTHRP] amino acids have been synthesized. Human (h) PTHRP (1–36) and (1–74) are potent bone-resorbing agents, and are catabolic for bone in vivo when given continuously at high doses. Bovine parathyroid hormone (bPTH) (1–34) is also catabolic for bone at high dose levels, but when given in low doses for weeks to months, it is anabolic. Although PTHRP possess several PTH-like properties in bone, hPTHRP (1–34) is reported to be only weakly anabolic in vivo. As polypeptide length influences PTHRP action, we evaluated hPTHRP(1–74) as an anabolic agent for bone in vivo. Twenty-four 4-week-old male Sprague-Dawley rats were given daily subcutaneous injections of hPTHRP(1–74) (1 and 2 nmol/100 g body weight, bw), bPTH(1–34) (4 nmol/100 g bw) or vehicle. Rats were sacrificed on day 12, and serum calcium, phosphorus, and 1,25 dihydroxyvitamin D and femoral bone dry weight, calcium content, and hydroxyproline content were measured. Serum calcium and phosphorus were equivalent in all groups. A significant increase in dry bone weight was observed in both PTHRP-treated groups compared with controls. PTHRP also caused a significant, dose-dependent increase in bone calcium and hydroxypro-line content. Results of these studies indicate that PTHRP (1–74) is anabolic for bone in vivo when administered at low-dosage levels for a prolonged period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296214
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Comparaison des propriétés mécaniques d'une nouvelle xénogreffe osseuse à celles de l'os trabéculaire humain et de Bovin (1992)
    Springer
    European journal of orthopaedic surgery & traumatology 2 (1992), S. 265-268 
    Details
    ISSN: 1432-1068
    Keywords: Bone ; Xenograft ; Young's modulus ; Biomechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The aim of the present study was to compare the mechanical properties of two types of a new bone xenograft, T650 (Luddoc®) (Dense and Medium) with human and fresh bovine trabecular bone. Compressive testing was performed to destruction with a constant deformation rate of 0,025 mm min−1. Shear destructive testing was also carried out. Under our experimental conditions, Young's modulus of dense T650 (132.9 ± 52.3 MPa) do not differ significantly from that of fresh bovine bone (117.5 ± 61.5 MPa); and that of medium T650 (79.92 ± 37.3 MPa) did not differ significantly from human bone (77,36 ± 54,9 MPa). The shear force is required to destroy dense T650 (494 ± 167 N) did not differ significantly from those for fresh bovine bone (558 ± 104 N). Whereas the values for medium T650 were significantly lower (359 ± 155 N). The stress-strain curves obtained from all the specimens did not differ significantly. The process used to obtain T650 did not modify the mechanical properties of bovine trabecular bone.
    Notes: Résumé Le but de ce travail est de comparer les propriétés mécaniques d'une nouvelle xénogreffe osseuse le T650 (Luddoc®) répartie en deux sous groupes dits “dense” et “moyen” à celle de l'os trabéculaire humain et de bovin. Des tests de compression avec un rapport de déformation constant de 0,025 mm min−1 et des tests de rupture au cisaillement sont appliqués. Dans les conditions expérimentales utilisées, le module de Young du T650 dense (132,9 ± 52,3 MPa) est comparable à celui de l'os trabéculaire frais de bovin (117,5 ± 61,5 MPa), celui du T650 moyen (79,92 ± 37,3 MPa) à celui de l'os humain (77,36 ± 54,9 MPa). La résistance à la rupture au cisaillement du T650 dense (494 ± 167 N) est comparable à celle de l'os trabéculaire de veau frais (558 ± 104 N). Les valeurs du T650 moyen sont significativement plus faibles (359 ± 155 N). Les courbes compression/déformation sont similaires pour les différents types d'éprouvettes testés. Les traitements subis par l'os trabéculaire de veau pour l'obtention du T650 n'affectent pas ses propriétés mécaniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01742445
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Decrease in bone strength of cadmium-treated young and old rats (1992)
    Springer
    Archives of toxicology 66 (1992), S. 315-320 
    Details
    ISSN: 1432-0738
    Keywords: Cadmium ; Rat ; Bone ; Long-term administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A decrease in mechanical strength of bones was observed both in young and old rats for long periods of administration of cadmium. Young (3-week-old) female rats were given 0 (control), 5 and 10 ppm cadmium in drinking water, respectively, for 20 weeks. Old (18-month old) female rats were given 0 (control) and 40 ppm cadmium in drinking water, respectively, for 7 months. The compression strengths of bones of young rats which were given 10 ppm cadmium, and those of old rats which were given 40 ppm cadmium, significantly decreased at the distal end portion of femur. Cadmium contents in bones in the 10 ppm and 40 ppm groups were about 110 and 210 ng/g dry weight, respectively. The present result confirmed that cadmium has a lesional effect on the mechanical strength of bone at the concentration of 100–200 ng/g in dry weight of bone, for both young and old rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01973625
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Craniofrontonasal dysplasia (1992)
    Springer
    European journal of pediatrics 151 (1992), S. 837-841 
    Details
    ISSN: 1432-1076
    Keywords: Frontonasal dysplasia ; Craniosynostosis ; Genetics ; X chromosome ; Psychomotor development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report on nine patients with craniofrontonasal dysplasia (CFND). Seven classical cases had facial features suggestive of frontonasal dysplasia and coronal craniosynostosis. Extracranial abnormalities such as brittle nails with prominent longitudinal grooves or syndactyly of fingers and toes were observed in individual patients. In two families the father of classical cases showed a milder pattern of abnormalities, consistent with the diagnosis. We present a 2- to 13-year follow-up on our patients. Hypotonia and laxity of joints are common and may necessitate supportive measures. Mild developmental delay was noted in three out of six classical cases studied in detail. Unlike almost all other X-linked disorders, clinical expression in CFND is generally much more severe in females than in males. In contrast to previous reports of this condition, one of our severely affected cases is a male.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01957936
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Usefulness of an acoustic edge artifact in assessment of the Ilizarov corticotomy interval (1992)
    Springer
    Skeletal radiology 21 (1992), S. 293-296 
    Details
    ISSN: 1432-2161
    Keywords: Ultrasound ; Bone ; Ilizarov ; Artifact ; Measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-three ultrasound examinations of the corticotomy interval of patients undergoing Ilizarov procedures were retrospectively evaluated for the presence or absence of an acoustic edge artifact. This artifact, consisting of a fine anechoic band, has been previously described in phantom models and is presumed to be due to phase cancellation effects. We demonstrated this artifact in 8 of 33 examinations. The artifact proved helpful in identifying the location of the corticotomy margin, even when this margin was obscured by the presence of developing periosteal new bone. Attention to technical factors is, however, important. We believe that this artifact may have a useful role in the routine monitoring of the Ilizarov patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241766
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Genetic and immunologic analysis of a family containing five patients with common-variable immune deficiency or selective IgA deficiency (1992)
    Springer
    Journal of clinical immunology 12 (1992), S. 406-414 
    Details
    ISSN: 1573-2592
    Keywords: Genetics ; immune deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A family with 13 members included 2 subjects with selective IgA deficiency (IgA-D) and 3 subjects with common-variable immune deficiency (CVID), diseases which usually occur sporadically. Reciprocal combinations of B and T cellsin vitro between one normal and two immune-deficient family members and normal subjects revealed that defective Ig synthesis was determined by the B cells, while the patient T cells functioned normally. Normal T helper and suppressor function was demonstrated even in one patient with CVID who developed a T-cell lymphoproliferative disorder associated with elevated IgM; this patient's B cells made only IgMin vitro. Immune deficiencies were inherited in this family in a pattern consistent with an autosomal dominant trait with incomplete penetrance. All the immune-deficient patients in this family possessed at least one copy of an MHC haplotype previously shown to be abnormally frequent in IgA-D and CVID: HLA-DQB1*0201, HLA-DR3, C4B-Sf, C4A-deleted, G11-15, Bf-0.4, C2-a, HSP70-7.5, TNFα-5, HLA-B8, and HLA-A1. The patient who developed the lymphoproliferative disorder was homozygous for this haplotype. Four immunologically normal members, one of whom was 80 years old, also possessed this MHC haplotype, indicating that its presence is not sufficient for disease expression. A small segment of another MHC haplotype associated with Ig deficiency in the population also occurred in this family, but it was not associated with immune deficiency. The presence of neutral amino acids at position 57 of DQβ, previously correlated with IgA-D, was associated with disease in this family approximately to the same degree reported previously in unrelated patients. Thus the expression of immunodeficiency in individuals bearing a disease-associated MHC haplotype appears to require either additional genes or an environmental trigger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00918852
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Type 2 (non-insulin-dependent) diabetes mellitus and glucose transporter gene (GLUT 1 andGLUT 4) polymorphism (1992)
    Springer
    Acta diabetologica 29 (1992), S. 110-112 
    Details
    ISSN: 1432-5233
    Keywords: Type 2 (non-insulin-dependent) diabetes mellitus ; Genetics ; Polymorphisms ; GLUT 4 ; GLUT 1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glucose transporter genes have been proposed as candidate genes for type 2 (non-insulin-dependent) diabetes mellitus. We chose to study the adult skeletal muscle glucose transporter gene (GLUT 4) andGLUT 1 in consideration of previous conflicting results obtained by different authors. We studied 68 patients with type 2 diabetes, and 66 non-diabetic controls matched for age, sex, and body mass index (BMI). Women and men were considered separately, according to BMI (≤24.0 and 〉24.0 for women; ≤25.0 and 〉25.0 for men). Allele and genotype frequencies were not significantly different in controls and in type 2 diabetic patients. ForGLUT 1 allele 1 and genotype x1x1 were more frequent, although not significantly (P=0.064 at χ2,P=0.025 at Fisher exact test) in overweight/obese diabetic women than in overweight/obese non-diabetic women. These data do not support the hypothesis that these genes play a major role in genetic susceptibility to type 2 diabetes mellitus, but suggest a possible association, at least in women, of allele 1 ofGLUT 1 with obese type 2 diabetes mellitus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572554
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Renal function in primary hypertension (1992)
    Springer
    Acta diabetologica 29 (1992), S. 173-177 
    Details
    ISSN: 1432-5233
    Keywords: Erythrocyte ; Genetics ; Renal function ; Sodium transport systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies of kidney cross-transplantation in the Milan hypertensive strain of rats (MHS) and in its control strain (MNS) have demonstrated that the kidney has a causal role in the development of hypertension in this animal model. The same result was obtained in two other strains of rats with genetic hypertension. Patients receiving a kidney from a donor with hypertensive parents require more antihypertensive therapy than recipients of a kidney from a donor with a normotensive family. When MHS rats and a subset of patients with primary hypertension were compared with their appropriate controls, similar changes in kidney function and Na−K−Cl cotransport were observed. Offspring of hypertensive parents exhibit altered kidney function compared with their controls. Na−K−Cl co-transport in MHS rats is genetically determined and genetically associated with hypertension. In MHS rats the increase in Na−K−Cl co-transport seems to be linked to a cytoskeletal protein, adducin. In conclusion, a consistent sequence of events from a protein abnormality to cell and renal dysfunction may be proposed as being responsible for hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00573483
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    The expression of salt tolerance from Triticum tauschii in hexaploid wheat (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 714-719 
    Details
    ISSN: 1432-2242
    Keywords: Wheat ; Salinity ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Accessions of Triticum tauschii (Coss.) Schmal. (D genome donor to hexaploid wheat) vary in salt tolerance and in the rate that Na+ accumulates in leaves. The aim of this study was to determine whether these differences in salt tolerance and leaf Na+ concentration would be expressed in hexaploid wheat. Synthetic hexaploids were produced from five T. tauschii accessions varying in salt tolerance and two salt-sensitive T. turgidum cultivars. The degree of salt tolerance of the hexaploids was evaluated as the grain yield per plant in 150 mol m-3 NaCl relative to grain yield in 1 mol m-3 NaCl (control). Sodium concentration in leaf 5 was measured after the leaf was fully expanded. The salt tolerance of the genotypes correlated negatively with the concentration of Na+ in leaf 5. The salt tolerance of the synthetic hexaploids was greater than the tetraploid parents primarily due to the maintenance of kernel weight under saline conditions. Synthetic hexaploids varied in salt tolerance with the source of their D genome which demonstrates that genes for salt tolerance from the diploid are expressed at the hexaploid level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224174
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Expression of mRNA of parathyroid hormone-related peptide in fetal bones of the rat (1992)
    Springer
    Cell & tissue research 270 (1992), S. 597-600 
    Details
    ISSN: 1432-0878
    Keywords: Parathyroid hormone-related peptide ; Osteocalcin-mRNA ; In situ hybridization histochemistry ; Bone ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous studies have indicated that 19-dayold fetal long bones of the rat contain an adenylyl cyclase-stimulating activity antigenically related to parathyroid hormone-related peptide. To ascertain its origin, Northern blotting and in situ hybridization histochemistry were performed. Results demonstrate that mRNA of parathyroid hormone-related peptide is present in RNA extracted from fetal long bones of the rat and that cells responsible for its production are localized in the periosteum. These cells are not mature osteoblasts because they do not synthesize mRNA of osteocalcin. Thus the present study shows that parathyroid hormone-related peptide could be produced locally, at least in part, in the skeleton of fetal rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645063
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Is pelvic bone mineral content assessed through dual energy X-ray absorptionmetry an appropriate anatomical area for bone mass estimation in women? (1992)
    Springer
    Clinical rheumatology 11 (1992), S. 508-511 
    Details
    ISSN: 1434-9949
    Keywords: Total ; Body ; Bone ; Mineral ; Content ; Pelvic ; Bone ; Mineral ; Content ; Postmenopausal ; Osteoporosis ; Bone ; Mass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bibliographic references seem very controversill regarding the most appropriate anatomical area for bone mass estimation. Since some overlapping in the different bone mass measurements among normal and osteoporotic females has been observed, we have studied the bone mineral content of the pelvic bone through DEXA, and have correlated it with the total body bone mineral content, a highly discriminating measure, in order to observe whether pelvic bone mineral may be a useful measure in bone mass assessment. Pelvic and total body bone mineral values did not decrease until menopause in 104 normal premenopausal females aged 20 to 49 years. On the other hand, these values decreased in normal postmenopausal women (n=44) aged 50 to 65 years (p〈0.001), with a 16% pelvic bone mineral content and an 11% total body bone mineral content decrease. Osteoporotic females (n=30), showed lower values for both levels than normal postmenopausal ones (p〈0.001), with a 54% pelvic and a 24% total decrease. A 15% overlap was observed when pelvic values between normal postmenopausal and osteoporotic females were compared. The greater percentage decrease in pelvic BMC compared to total body bone mineral content and the lower overlap observed suggest that the pelvis may be an ideal anatomical area for bone mass evaluations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02283108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Application of cladistics to the analysis of genotype-phenotype relationships (1992)
    Springer
    European journal of epidemiology 8 (1992), S. 3-9 
    Details
    ISSN: 1573-7284
    Keywords: Atherosclerosis ; Cladistics ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We seek to understand the relative contribution of allelic variations of a particular gene to the determination of an individual's risk of atherosclerosis or hypertension. Work in progress is focusing on the identification and characterization of mutations in candidate genes that are known to be involved in determining the phenotypic expression of intermediate biochemical and physiological traits that are in the pathway of causation between genetic variation and variation in risk of disease. The statistical strategy described in this paper is designed to aid geneticists and molecular biologists in their search to find the DNA sequences responsible for the genetic component of variation in these traits. With this information we will have a more complete understanding of the nature of the organization of the genetic variation responsible for quantitative variation in risk of disease. It will then be possible to fully evaluate the utility of measured genetic information in predicting the risk of common diseases having a complex multifactorial etiology, such as atherosclerosis and hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145343
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    High-resolution immunolocalization of osteopontin and osteocalcin in bone and cartilage during endochondral ossification in the chicken tibia (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 234 (1992), S. 479-492 
    Details
    ISSN: 0003-276X
    Keywords: Bone ; cartilage ; growth plate ; mineralization ; osteopontin ; osteocalcin ; osteoblast ; osteoclast ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructural distribution of two noncollagenous proteins, osteopontin (OPN) and osteocalcin (OC), originally extracted from bone matrix and proposed to play an important role in bone formation, was examined in the matrices of bone and cartilage from embryonic and postnatal chicken tibial growth plates by high-resolution immunocytochemistry using the colloidal gold technique. In bone, immunolabeling patterns using polyclonal antibodies against chicken OPN and OC were generally similar in that both showed an intense, but regionally variable, labeling of mineralized bone matrix and small mineralization loci dispersed throughout the osteoid and containing prominent condensed organic material. Unmineralized osteoid showed weak-to-moderate labeling. In the mineralized bone matrix proper, labeling was predominantly associated with amorphous, electron-dense patches of organic material among the collagen fibrils. In growth plate cartilage, both proteins first appeared related to calcified cartilage in the hypertrophic zone, although the labeling patterns were somewhat different. For OPN, gold particles were mostly associated with an organic lamina limitans-like density containing condensed, filamentous organic matrix at the periphery of small nodules and large masses of calcified cartilage, with additional moderate labeling throughout the interior of the calcified cartilage. For OC, labeling was observed over filamentous structures throughout the calcified cartilage matrix, with some, but less, labeling at the periphery. In the lowermost zones of the growth plate, the major reaction using both antibodies was found over a layer of dense, amorphous organic material at the periphery of the calcified cartilage at the future bone/calcified cartilage interface, a labeling pattern that persisted following bone deposition at these sites. OPN and to a lesser extent OC were also concentrated in cement (resting, reversal) lines. Throughout the bone and cartilage of the tibia, cells of both the osteoblastic and the osteoclastic lineages were found directly apposed to labeled surfaces and lamina limitans of organic matrix containing OPN and OC. In summary, it is concluded form the immunocytochemical data presented here that the association of OPN and OC with mineralized regions of the extracellular matrices of bone and cartilage and the accumulation of these proteins at tissue surfaces and interfaces are consistent with the hypotheses that they play a role in the extracellular mineralization process per se and/or that they may mediate cell adhesion and dynamics.© Willey-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092340404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    O-versus S-protonation in diaryl sulfoxides: A semi-empirical mo investigation: Comparison with solution studies in superacids (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 244-252 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The protonation of diphenyl sulfoxide and several substituted diphenyl sulfoxides was probed by the MNDO-PM3 method to gain a theoretical insight into the experimentally observed preference for stable diphenyl sulfoxonium ion formation (O-protonation) in 1:1 FSO3H - SbF5 (Magic Acid) - SO2. In agreement with solution studies, O- protonation is uniformly favored (by ca 17 kcal mol -1) over S-protonation. The differences in the heats of formation of protonated and unprotonated diphenyl sulfoxides are increased by electron-withdrawing substituents (F, CF3) and decreased by electron-donating groups (Me, OMe). Variations in the SO bond length and bond order in the onium ions are compatible with simple resonance arguments and the oxonium/sulfonium character of both the O- and S-protonated onium ions. Surprisingly, the O- and S-protonated dibenzothiophene S-oxides are predicted to have identical energetics as compared with the corresponding protonated diphenyl sulfoxides. On structure optimization dibenzothiophene S-oxide itself, if the initial geometry is somewhat twisted, rearranges by ring expansion to give a new heterocycle with lower energy. A rotational barrier study on the parent O-protonated diphenyl sulfoxide showed two minima, separated by 1.3 kcal mol-1, at HOSC dihedral angles of 60° and 240°. The two conformations correspond to syn and anti orientations of the OH proton relative to the aromatic rings, and support the lowtemperature solution observations of the presence of two distinct sulfoxonium ions in solution. The rotational barriers for diphenyl sulfoxonium cation are compared with those of O-protonated dimethyl sulfoxide.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Theoretical studies on nitrile-forming elimination reactionsDetermination of Reactivity by MO Theory, Part 73. Part 72, 1. Lee, C. K. Kim, B. H. Kong and B. C. Lee, J. Phys. Org. Chem. 4, 449 (1991). (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 259-268 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The base-promoted nitrile-forming elimination reactions of YCH=CHCβH=NOCH=CHZ (Y=OCH3, H or Cl and Z=H or NO2) were studied by the AM1 MO theoretical method with Cl- as a base. The reaction is found to proceed by an E1cB-like E2 mechanism in which Cβ - H bond cleavage is more advanced than N - O bond breaking. The syn-elimination has a more E1cB-like transition state (TS) than the anti elimination, which is attributed to the structurally favourable nN - ó * (Cβ - H) charge-transfer interaction. An electron-withdrawing Y substituent lowers the activation barrier by stabilizing negative charge developed on Cβ in the TS. An electron-withdrawing substituent in the leaving group (Z = NO2) tends to enhance the anti relative to the syn elimination process by depressing the δ*(N - O) level, which in turn makes the nć - δ*(N - O) interaction more effective. The YCH=CH -  and  - CβH=N fragments are perpendicular in the TS, which is stabilized by delocalization of negative charge developed on the Cβ atom.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Stabilization of molecular association: An AM1/PM3 study of tetrahalomethane-arene molecular complexes (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 253-258 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An AM1/PM3 study of several tetrahalomethane-arene molecular complexes is presented. The results indicate the existence of weak attractive non-dispersion interactions in some of these complexes, which can be rationalized in terms of multipole - multipole and multipole - induced dipole interactions. No evidence was found for the occurrence of charge transfer in the ground states of these complexes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050601
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Direct measurement of the energy barrier for 1,2-chlorine atom migration in α-methyl-α-chlorobenzyl(chloro)crbene (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 285-286 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The first direct determination of a 1,2-chlorine atom shift in a chlorobenzylcarbene was achieved by nanosecond laser flash photolysis. Arrhenius activation parameters of Eact = 3.39 ± 0.14 kcal mol-1 and log [A(s-1)] = 10.98 ± 0.14 were obtained for 1,2-chlorine migration in α-methyl-α-chlorobenzyl(ch1oro)carbene. The lifetime of this carbene is considerably longer than previously estimated and the measured Eact, is in excellent agreement with that determined by product analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050510
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Alkylation of pyridinium-N-phenoxide betaine dyes with iodomethane: Substituent, solvent and temperature dependence (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 275-284 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate constants of the pseudo-first-order methylation reaction of seven substituted pyridinium-N-phenoxide betaine dyes by iodomethane, were determined by UV-visible spectrophotometry in nine different solvents. The influence of substituents on the position of the long-wavelength, intramolecular charge-transfer absorption band of the unsubstituted betaine dye can be described by a modified Hammett equation. The solvent-dependent absorption constant ρA correlates satisfactorily with the acceptor properties of the nine solvents used. The substituent-dependent alkylation rate constants (In k) correlate linearly with the Hammett substituent constants, whereas the solventdependence of in k follows a more complicated pattern. Temperature-dependent measurements of the rate of alkylation exhibit an isoenthalpic behaviour for all the betaines in all the solvents investigated, i.e. the Arrhenius activation energy is almost constant for all differently substituted betaines in a given solvent. Temperature-dependent measurements of the alkylation rate of the unsubstituted betaine in different solvents led to an isosolvent relationship, i.e. the corresponding Arrhenius plots show a common point of intersection. According to the theory of isokinetic relationships, this isosolvent behaviour is interpreted in terms of a resonant energy exchange between the reacting species and the surrounding heat-bath system, which in this particular case seems to be the betaine molecule itself.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050509
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Quantitative aspects of chirality. I. Method of dissymmetry function (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 295-298 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To study molecular features connected with chirality, a procedure for the quantitative estimation of the chirality level of compounds of different classes is needed. A procedure for estimating the molecular asymmetry level relative to mirror-reflection axes of symmetry, S1, S2, S4 and S6, has been developed. The geometrical mean of these parameters is the disymmetry function (DF). To calculate the DF, the molecule must be fixed in the coordinate system, transferred to the main axes of inertia.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050603
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Quantitative aspects of chirality. II. Analysis of dissymmetry function behaviour with different changes in the structure of the model systems (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 299-307 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The efficiency of the developed method of dissymmetry functions was studied using various model systems. The alteration of the dissymmetry function was analysed with systematic variations of the bond lengths, valence angles and masses of atoms in model tetrahedra. The behaviour of the dissymmetry function was studied for conformationally labile systems and chiral polyhedra. In general, it was found that in all cases the alteration of the dissymmetry function is in agreement with the speculative representations of the changes in degree of chirality.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050604
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Concerning the development of scales of solvent ionizing power based on solvolyses of benzylic substrates (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 287-294 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Based on analysis of recently reported measurements, it is suggested that, provided a sufficiently large set of specific rate measurements in a wide variety of solvent types is available, the negligible to moderate improvements in the correlations of other types of benzylic chlorides, which are gained by use of a benzylic chloride (in place of 1-adamantyl chloride) as the standard substrate, do not justify the development of new specialized scales of solvent ionizing power. A similar conclusion is reached concerning solvent ionizing power scales developed for use with benzylic p-nitrobenzoates. However, such scales could be helpful when specific rates of solvolysis in only a limited variety of solvents are available, e.g. when a change in mechanism severely limits the range of operation of one of the pathways. Contrary to a previous claim, variations in ion-pair return could be the cause of deviations from Grunwald-Winstein plots for solvolyses of benzhydryl chloride in fluorinated alcohol solvents; such effects could be coupled, at least in part, with variations in aromatic ring solvation.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050602
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Charge-transfer transition energies and the prediction of reactivity in electrophile-nucleophile reactions (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 317-321 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The differences between charge-transfer transition energies calculated for donor-acceptor pairs at infinite separation and values determined experimentally for the charge-transfer complex geometry vary according to the charge type of the pairs and within a group of fixed charge type. It is argued that these differences provide a guide to the slope of the state-correlation curves for the product configuration in electrophile-nucleophile reactions of the corresponding charge type and that the observed variation invalidates the use of the simple expression ΔE=fΛ-β with constant f, derived from the curve-crossing model, to estimate energy barriers to reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Quantitative aspects of chirality. III. Description of the influence of the structure of chiral compounds on their twisting power in the nematic mesophase by means of the dissymmetry function (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 308-316 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For a number of chiral α,β-unsaturated carbonyl compounds, cyclohexanone and cyclohexenone derivatives, existing essentially in the form of single molecular conformation, the correlation dependences were established between the values of the calculated dissymmetry functions (DF) with respect to atomic masses and atom refractions, and the induction effectiveness of helical ordering in the nematic mesophase (twisting power). Such correlative dependencies, as the examples show, allow one to predict safely enough the twisting power of new substances with the ‘fixed’ molecular conformation. Types of dissymmetry functions and kinds of correlative dependences, the most acceptable for these reasons, were revealed. Dissymmetry functions formed on the basis of atom refractions (polarizabilities) describe the influence of the molecular structures of chiral compounds on the twisting power with higher accuracy than those that characterize the dissymmetry of the atomic masses distribution, according to the important role of the dispersion forces in the formation of helical ordering in liquid crystalline systems. The components characterizing the distribution dissymmetry of atomic refractions and masses with respect to the long and two shorter axes as the peculiar characteristics of biaxiality of chiral molecules describe the influence of the molecular structure on the twisting power with the same accuracy as the general DF do. Thus influence of chiral dopant molecules on the interactions between molecules in the uniaxial mesophases is negligible within the limits of the DF method. Based on the calculations for model systems it is established that the presence of the non-linear cinnamoyl fragment has a decisive influence on the molecular dissymmetry of the chiral α,β-unsaturated ketones. The alkyl groups influence the molecular dissymmetry only slightly, but it is important that their presence ensures the stabilization of the chiral conformer with the defined helicity of the cinnamoyl fragment.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050605
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Solvent and secondary substrate isotope effects on the acid-catalyzed ketonization of acetophenone enol in aqueous solution (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 322-326 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enol of acetophenone was generated flash photolytically in aqueous solution by photosolvolysis of PhCBr=CH2 and photohydration of PhC≡CH and PhC≡CD, and rates of its ketonization were measured in dilute perchloric acid solutions in H2O and D2O at 25°C. The rate constants so obtained provide the solvent isotope effects, kH+/kD+ = 5.02 ± 0.08, and the secondary isotope effect for deuterium substitution at the β-position of the enol double bond, (kH/kD)β = 0.999 ± 0.014. Arguments are presented which show that these isotope effects requre a stepwise rather than a concerted mechanism for the ketonization reaction.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050607
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    New kinetic methods. 2.For Part 1 of this series, see Ref. 5. An indirect measurement of ester formation and hydrolysis rates (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 334-340 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The use of an assistant reagent to monitor spectroscopically the concentration of compounds that lack chromophores is described. It is demonstrated, for example, that the concentration of an aliphatic alcohol (present during acidcatalyzed hydrolysis or esterification reactions) can be monitored continuously by addition of a small amount of chromium trioxide. From a knowledge of the rate law and the rate constants for chromic acid oxidations, - d [CrO3]/dt = k [alcohol] [CrO3], the concentration of alcohol can be determined at any time by monitoring the absorbance of chromic acid at 363 nm. The rate at which the concentration of the alcohol is changing can then be used to calculate rate constants for the corresponding esterification or hydrolysis reactions. Rate constants obtained in this way are compared with those previously obtained by use of direct methods, and the application of this approach to the study of kinetics under conditions not accessible by other methods is illustrated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050609
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Ionization constants of 5-furylmethylenehydantoins and 5-thienylmethylenehydantoins in 80% (w/w) dimethyl sulphoxide-water at 25°C (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 349-354 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ionization constants of sixteen 5-furylmethylenehydantoins and 5-thienylmethylenehydantoins were measured in 80% (w/w) dimethyl sulphoxide-water solvent at 25°C. The effects of the 2-/3-furyl and 2-/-3-thienyl rings and the effects of configuration and conformation on acidity are discussed. The very low acidity of (Z)-5-(2-furyl)methylene-3-methylhydantoin suggests the possibility of some weak intramolecular interaction between the proton at N-1 and the 2-furyl oxygen in the s-cis conformation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Reactions of molecules with two equivalent functional groups. 3. Nucleophilic substitution reactions of α, ω-dibromoalkanes [Br(CH2)nBr, n = 3,4,5] with potassium cyanide (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 327-333 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The substitution reactions of Br(CH2)nBr(1, n = 3-5) with KCN in methanol were studied in detail. Second-order rate constants k1 [formation of the mononitrile (2) from 1] and k2 (formation of the dinitrile (3) from 2) were determined, as were the rates for the reaction of H(CH2)nBr (4, n = 3-5) with KCN under the same conditions. The ratios k2/k1 ( = x) of the three homologs of 1 were found to be 1.15, 0.77 and 0.61 for n = 3, 4 and 5, respectively; a x value of 0.5 indicates that the functional groups behave independently. The second-order rate constants k1 (statistically corrected) and k2 exhibit modest enhancements compared with model compound 4 when any of the following substituents are present: δ or ∊-bromo, γ-, δ-, or ∊-cyano. By contrast, a γ-bromo substituent slightly retards the rate. These results indicate that the functional groups do influence each other to a modest degree by field effects which accelerate the reactions. Steric effects do not appear to play a significant role.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050608
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Catalysis in nucleophilic aromatic substitution reactions. A reinvestigation of the reaction between 1-fluoro-2,4-dinitrobenzene and n-butylamine (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 429-434 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction between 1-fluoro-2,4-dinitrobenzene and n-butylamine in toluene shows a two-step plot of kobs, values vs the initial values of the concentration of the amine. The usual base-catalysis mechanism for HF elimination from the zwitterionic intermediate hardly explains this kinetic behaviour and the kinetic effect of addition of salts (and of 2-hydroxypyridine) to the reaction mixtures at different initial values of the concentration of n-butylamine. In contrast, the kinetic behaviours are easily explained by the presence of substrate-amine (or catalyst) interactions on the pathway of the substitution reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Comparative study of aromaticity in five-membered rings containing S, SO and SO2 groups (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 74-82 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Owing to the importance of the concept of aromaticity, different indices have been developed to try to quantify this property. The possible π delocalization through an X—SOn—X group (X = C, N; n = 0, 1 or 2) could explain heteroaromaticity in rings containing the moiety. For that reason, the aromaticity of five-membered sulphurcontaining rings with different oxidation numbers (S, SO and SO2) and including no (thiophene), one (isothiazole) or two (1,2,5-thiadiazole) adjacent atoms was investigated. Ab initio calculations were carried out to determine geometrical parameters (planarity of the ring, bond length and bond order), electronic structure (charge distribution and dipolar moment) and the participation of d-orbitals of sulphur. According to these calculations, only compounds with S(II) can be considered to be aromatic, whereas compounds bearing S(IV) or S(VI) are better described as ylides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Hydrolyses of terpenoid diphosphates. Effects of azide ion on products of hydrolysis (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 83-92 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hydrolysis of geranyl diphosphate (GPP) at pH 7 in water gives largely linalool (LOH) + geraniol (GOH) in the ratio of 3:1. Added N-3 generates mixed acylic allylic azides and increases the LOH GOH ratio to 15:1 in 2 M NaN3, but does not speed up the overall reaction. Hydrolysis of neryl diphosphate (NPP) gives largely α-terpineol (TOH) +p LOH, but their ratio is not very sensitive to NaN3 concentration although acyclic azide and small amounts of α-terpinyl azide (TN3) are formed. Hydrolysis of α-terpinyl diphosphate (TPP) gives large amounts of the cyclic alkenes, limonene and terpinolene. Added N-3 does not change the amount of elimination, but increases the ratio of limonene to terpinolene, and diverts some substitution product to TN3. Trapping of carbocationic species from GPP by N-3 is sharply increased by addition of Mn2+, which also catalyzes the overall reaction. Products of reaction of GPP are derived from acyclic intermediates and of NPP from acyclic and cyclic intermediates, and ionizations of the three substrates do not generate common carbocationic species.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Cyclopropylmethoxycarbene: A kinetic limit on the 1,2-carbon migration (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 104-107 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cyclopropylmethoxycarbene undergoes ambiphilic-nucleophilic intermolecular reaction with alkenes and methanol, but its intramolecular chemistry (1,2-carbon migration) is suppressed (k 〈 3 × 103 s-1) by the α-methoxy substituent.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050301
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Chemiexcitation of an anthraquinone derivative in the thermal cycloreversion of a dewar-anthraquinone derivative (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 101-103 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dewar-anthraquinone (1a) and 1,2,3-tri-tert-butyl-5,8-Dewar-anthraquinone (1b) were synthesized. Thermodynamic parameters for their cycloreversion to the corresponding anthraquinones indicate that thermal population of the excited states of the products via non-adiabatic valence isomerization is energetically feasible. On thermolysis of 1b, the formation of a detectable amount of 1,2,3-tri-tert-butyl-1,4-Dewar-anthraquinone (3) was observed. The excited singlet state of 1,2,3-tri-tert-butylanthraquinone (2b) produced via the non-adiabatic process is responsible for the formation of 3.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Molecular modelling of organophosphorus podands and their complexes with alkali metal cations (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 109-118 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A molecular mechanics study on some organophosphorus podands, with both rigid and flexible terminal groups, and on their complexes with Li+ and Na+ was carried out. Na+ causes smaller deformations of the ligands than Li+, but its complexes are less stable, as the interaction energy with the podands is weaker. The ligands with rigid terminal groups are, in general, more pre-organized for complex formation. The cation-ligand interaction energies, including also the changes in steric energies, are always higher in complexes of flexible molecules than in those containing rigid ligands. The lower entropy losses which accompany the formation of complexes of rigid molecules with alkali metal cations probably account for the observed higher stabilities of the complexes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Hammett reaction constants for irreversible electroreduction of iodobenzenes in non-aqueous solvents (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 119-122 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polarographic half-wave potentials for the electrochemical reduction of a series of para-substituted iodobenzenes in acetonitrile, acetone, benzonitrile, dimethylformamide, dimethyl sulphoxide and methanol obey Hammett equations and the reaction constant found, ρ = 0·36 ± 0·02, is independent of the solvent used. The results obtained are discussed on the basis of a mechanism of the electrode process.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Enthalpies of solution and intermolecular forces. tert-butyl halides in hydroxylic solvents (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 93-100 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The application of cavity theories of solution and linear solvation energy relationships to the interpretation of enthalpy of solution values of tert-butyl halides in hydroxylic media, measured at 25 °C and infinite dilution, is deserted, in order to define the intermolecular forces acting between solutes and solvents. It is concluded that solvent dipolarity and solvent HBD acidity effects dominate the solution process. An empirical equation relating the enthalpies of solution with selected properties of both solvents and solutes is proposed. New experimental Δ Hs∞ values for tert-butyl iodide in 13 alcohols are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Laser flash photolysis study of 10, 10-dimethyl-9-anthrylidene, a carbene with nearly degenerate singlet and triplet states (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 123-128 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 10, 10-Dimethyl-9-anthrylidene (DMA) was studied by laser flash photolysis (LFP) techniques. LFP of the requisite diazo precursor in pentane or carbon tetrachioride produced transient spectra attributed to the hydrocarbon and monochlorinated diarylmethyl radicals, respectively. In the presence of pyridine and oxygen, ylides were formed upon LFP of 10, 10-dimethyl-9-diazoanthrone. However, ylides are not formed in acetonifrile or acetone. The carbene itself was not detected by transient absorption spectroscopy. The absolute rate constants for reaction of DMA with pyridine, methanol and triethylsilane are 1·96 × 109, 1·8 × 1010, and 1·0 × 108 I mol-1 s-1, respectively. It is concluded that the singlet and triplet states of DMA are essentially degenerate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Transimination reaction between pyridoxal-5′-phosphate schiff bases with dodecylamine and amino acids (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 142-154 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some transimination processes were studied using an intermolecular model formed by pyridoxal-5′ -phosphate (PLP) an amino acid and dodecylamine (DOD) in an aqueous medium. All the kinetic constants for the reversible reaction were determined. The results show that in these cases transimination proceeds through an addition-elimination by forming a diamine geminal intermediate. Equilibria are always shifted to dodecylamine-PLP Schiff base formation. Differences between the stability of this Schiff base and the ∊-aminocaproic Schiff base cannot be explained only on the basis of the different nucleophicities of amine groups and therefore differences in the imine double bond environment must be taken into account to explain this behaviour.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050306
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Cycloaddition of heterofunctionalized allenes with tert-butylthioacrylonitrile. Determination of activation parameters for diradical intermediate formation and the detection of reversible ring closure (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 160-170 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cycloaddition reactions of 4-methylphenylthio-, methoxy-, 4-methoxyphenyl-, phenyl-, chloro- and cyanoallene with tert-butylthioacrylonitrile (BTA) in toluene-d8 solution were investigated. The relative reactivity sequence of these substituted allenes is 4-methylphenylthio ∼ methoxy- 〉 4-methoxyphenyl- 〉 phenyl- 〉 chloro- 〉 cyanoallene. Activation parameters were measured for diradical intermediate formation of BTA with 4-methylphenylthio-, methoxy- and 4-methoxyphenylallene, giving average values of Ea and ΔS± of 14.2-16.8 kcal mol-1 and ca. -33 eu, respectively. The relative reactivity sequence is consistent with a FMO allene-HOMO, BTA-LUMO dominant interaction for diradical intermediate formation. However, the regioselectivity of attack on the substituted allene appears to be thermodynamically controlled. The formation of the diradical intermediates in these cycloaddition processes appears to be irreversible. However, the ring closure of the diradical intermediates formed from 4-methylphenylthio-, methoxy- and 4-methoxyphenylallene is reversible under the conditions of the kinetic experiments. The kinetically controlled ring closure of the diradical intermediates is allyl radical SOMO controlled, while the final cycloadduct distribution is thermodynamically controlled.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050308
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050401
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Protonated propylene oxide is stable towards isomerization in the gas phase (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 201-208 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative stabilities of gaseous protonated propylene oxide and its isomers, protonated propanal, oxetane and acetone, were reinvestigated in a Fourier transform ion cyclotron resonance mass spectrometer by using multiple-stage tandem mass spectrometri experiments. The dependence of ion structure on internal energy was examined by generating the ions in proton transfer reactions with different exothermicities and then probing their structures by using energy-resolved mass spectrometry (collision-activated dissociation as a function of collision energy). In contrast to results obtained in several recent investigations, protonated propylene oxide was found to be distinct from its more stable isomers when generated with only a small amount of internal energy. When the exothermicity of the proton transfer reaction was higher than 6 kcal mol-1 (1 kcal = 4·184 kJ) or when the epoxide ion was subjected to multiple activating collisions, rapid isomerization to protonated propanal occurred. The energy required for opening of the epoxide ring estimated to be similar to that measured earlier for protonated cyclohexene oxide (5-10 kcal mol-1).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    ESR study of solvent effects on the electronic structure of 2-(4′ -dialkylaminophenyl)indan-1,3-dionyl radicals (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 218-224 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ESR spectra of 2-arylindan-1,3-dionyl radicals in various solvents at 343 K were obtained and assignments of the hyperfine structures were made. The hyperfine coupling constant (hfcc) of the dimethylamino nitrogen increases whereas the 2',6'-hydrogen hfcc decreases as the ET value, a solvent polarity parameter, increases. MO calculations were made according to the semi-empirical procedure of Rieger and Fraenkel; the nitrogen and oxygen Coulomb integrals were adjusted so that the calculated spin density on the nitrogen atom agrees with that estimated from its hfcc. It is found that the π-moment of the radicals increases from 9·13 D in toluene to 9·85 D in acetic acid. The solvent dependence of the equilibrium between the radicals and its dimer has been explained in terms of the solventinduced π-moment in polar solvents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Heats of formation of organic molecules by ab initio calculations. Aldehydes and ketones (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 225-229 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A bond and group equivalent scheme that allows the calculation of heats of formation for aldehydes and ketones from ab initio 6-31G* energies has been developed. For a group of 24 aldehydes and ketones, the RMS error for the calculated heat of formation was 0 · 46 kcal mol-1. Heats of formation have been predicted for an additional seven compounds for which the experimental values are believed to be either in error or unknown. There are some problems with the norbornanones.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050502
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Substituent effect on the relative strength of some arylthiomethyl- and arylsulphonylmethylbenzoic acids (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 239-243 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pK values of some arylthiomethylbenzoic acids and the corresponding sulphones were determined spectrophotometerically. The role of substituent and the position of the carboxylic group are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050504
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Experimental and theoretical study of the influence of the solvent on asymmetric diels - alder reactions (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 230-238 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rate, endo/exo and diastereofacial selectivities of the Diels-Alder reaction between cyclopentadiene and ( - )-menthyl acrylate were measured in a series of organic solvents and organic-aqueous mixtures. Regression analyses show that a model with the α empirical solvent parameter accounts for most of the changes in rates and diastereofacial selectivities, whereas in the case of the endo/exo selectivity, inclusion of the π* and δ parameters is needed. Theoretical calculations carried out on the model reaction between methyl acrylate and cyclopentadiene using dielectric continuum and supermolecule models do not clearly show the effect of the different solvation mechanisms on rate. However, they agree with the above-mentioned influence of α and π* on the endo/exo and diastereofacial selectivities.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050503
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Enhancement or suppression of CIDNP intensities by a second magnetic nucleus: Interplay between g factor difference, external magnetic field, and hyperfine coupling constants (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 209-217 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enhancement factors of the 1H polarization induced in radical pairs generated by α-cleavage of 12C=O- and C=O-labelled ketones deviate from the ratios expected on the basis of the relative abundances of the respective carbon isotopomers. For dibenzyl ketone, the ratio of absolute CIDNP intensities of the 1H(13C) doublet (90% 13C=O) to the 1H(12C) singlet (10% 12C=O) was found to be 〉9:1 at 58·3 kG and 〈9:1 at 21 kG. Similar deviations were observed for other 13C labelled ketones, viz. deoxybenzoin (13C=O) and acetophenone (13C=O or 13CH3). This novel enhancement or suppression effect on the CIDNP enhancement can be ascribed to the presence of a second hyperfine coupled nucleus in the intermediate radical pair. The individual contributions of the g factor difference (Δg), the external magnetic field strength (Ho), and the hfc constants of the observed (aA) and the interacting nucleus (ax) in the enhancement-suppression are exemplified. The experimental results are consistent with theoretical calculations of the mutual effect of Δg, H0, aA and ax on the CIDNP enhancement factor of the observed nucleus.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Reduction of 1-benzyl-3-cyanoquinolinium ion by phosphonate: Solvent effects in propan-2-ol-water mixed solvents (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 269-274 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rate constants (k2) were determined for the reduction of 1-benzyl-3-cyanoquinolinium ion by phosphonate dianion in mixed solvents consisting of propan-2-ol and water. The reduction product was mostly 1-benzyl-3-cyano-1,4-dihydroquinoline with a trace of the 1,2-isomer. The solvent properties were varied by increasing the fraction of water in the mixed solvent, which increases the polarity of the solvent. Increasing the proportion of alcohol makes the solvent a better electron pair donor. The higher fraction of propan-2-ol in the mixed solvent gives rise to a substantial increase in k2. A quantitative comparison of the solvent effect on this reaction with the solvent effects on related reactions suggests a solvent Brønsted α value of 0·45. This suggests that the PO3- unit of the transition state interacts only weakly with the solvent although the final oxidized product is phosphate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Interaction of formamide with stilbazolium betaines: Steric effects in amides (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 609-613 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The visible spectrum of di-tert-butylstilbazolium betaine (DTBSB) was recorded in eight simple amides. The appearance of a ‘coarse’ structure in the main absorption band is due to the shielding effect of the tert-butyl groups, which hinder the approach of the solvent. Since this structure disappears in formamide, it is concluded that this solvent associates through its NH to the carbonyl group of DTBSB. For the other amides, there is a clear relationship between the steric effect, for both the N- and C-substituents, of the solvent-solute hydrogen bond association and the structure of the visible band.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050909
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Structure of, and internal rotation in, hexakis [4-(2-phenylpropan-2-yl) phenoxy] benzene, and structural comparison with its precursor phenol 4-(2-phenylpropan-2-yl)Phenol (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 628-632 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The title compounds (1 and 3, respectively) were studied by X-ray crystal structure analysis. Both are trigonal, space group R3, with lattice parameters a = 27.718(6), c = 8.161(2) Å, Z = 3 and a = 31.267(7), c = 6.560(2), Z = 18, respectively. The dodecamethyl compound 1 is isomorphous with its parent hexakis(4-benzylphenoxy)benzene (2), a known host. However, ‘collapse’ along the c-axial direction has occurred such that the appreciable clathrate cavity of 2 has been replaced by only a very small residual void for 1. Phenol 3 does not pack in discrete [OH]6 hydrogenbonded hexamers; instead, molecules are assembled in infinite chains, linked by OH…O hydrogen bonds of length 2.735(3) Å, which are propagated along threefold screw axes. A variable-temperature CPMAS NMR study of sidechain aryl group rotation in 1 gives a value ΔG≠ of 14.0 ± 0.7 kcal mol-1 (at 42 °C) for the (crystallographically unique) para -disubstituted ring, a similar 14 kcal mol-1 free energy barrier being found hindering rotation of this ring, and of the outer phenyl ring of 1, at 9°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051003
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Diastereofacial selectivity in 1,3-dipolar cycloadditions to cyclobutens. 8. HF/3-21G transition structures of the reactions of formonitrile oxide with CIS-3,4-dichlorocyclobutene and norbornene (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 819-823 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A transition structure for the syn and anti attack of formonitrile oxide on both cis-3,4-dichlorocyclobutene and norbornene was obtained using HF/3-21G method. These calculations correctly predict dominance of the syn attack in the reaction of dichlorocyclobutene and 100% syn selectivity, with respect to the methano bridge, in the reaction of norbornene. Analysis of the activation energy shows that the inherent facial bias of dichlorocyclobutene is reflected, at the transition state, in a complex way in the deformation energy of both dichlorocyclobutene and formonitrile oxide and in the interaction energy between them. With norbornene the out-of-plane deformation energy of the olefinic hydrogens clearly emerges as the major factor in controlling facial selectivity.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051001
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Effect of hexadecyltrimethylammonium bromide micelles on the rate of oximolysis of esters (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 341-348 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two amphiphilic oximes, 10-phenyl-10-hydroxyiminodecanoic acid (oxime II) and 4-(9-carboxynonanyl)-1-(9-carboxy-1-hydroxyimino nonanyl)benzene (oxime III) were synthesized. The pKa values of oximes II and III and acetophenoxime (oxime I) and the rates of oximolysis of p-nitrophenyl acetate (NPA) and p-nitrophenyl octanoate (NPO) were determined in the presence and absence of micellar hexadecyltrimethylammonium bromide (CTAB). The rates of oximolysis increased by up to 3 × 104-fold in the presence of CTAB. Quantitative analysis of micellar effects, using an ion-exchange pseudo-phase model, allowed the determination of the second-order rate constants for the reactions of oximes I-III with NPA and NPO in the micellar pseudo-phase. The calculated rate constants in the micellar pseudo-phase were lower than those in water, demonstrating that the rate enhancements were due to substrate concentration in the micelles. Comparison of the rate constants in micelles and water suggests that the sites of reaction of oximes I-III with NPO and NPA are similar to those in bulk aqueous solution. Micellar incorporation of the hydrophobic oximes II and III does not lead to a major change in the nucleophilicity of the oximate anion.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Photochemical reactions of 2,2′-furil. Solvent dependent photoreduction via the lowest excited singlet and triplet states (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 355-360 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2,2′-Furil (di-2-furyl diketone) undergoes photoreduction to give furoin on irradiation at 366 nm in triethylamine-containing benzene and ethers. On the other hand, in ethanol the photoirradiation leads to the formation of an enediol type of compound, 1,2-di(2-furan)ethene-1,2-diol. The results of quenching and sensitization both for the photoreactions and the phosphorescence demonstrate that furoin and the enediol are formed via the lowest excited singlet and the triplet states of 2,2′-furil, respectively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050612
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050701
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Quantum mechanical and molecular mechanical studies of the hydrolysis of methyl nitrate and the solvent effect (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 361-366 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkaline hydrolysis reaction of methyl nitrate was simulated by quantum mechanical and molecular mechanical methods. The gas-phase reaction was calculated to proceed with no barrier when ab initio calculations at the STO-3G level were utilized, and with a very small barrier (5.70 kJ mol-1) when the MINDO/3 method was applied. In solution, the solvation energy was estimated to be 70.33 kJ mol-1 by molecular mechanical calculations. Thus the activation energy (76.03 kJ mol-1) of alkaline hydrolysis of methyl nitrate was found to be in good agreement with the available experimental value (82.42 kJ mol-1). The results indicated that the substantial activation barrier in alkaline hydrolysis was essentially solvent-induced.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Solvolysis of 1,1-diphenylethyl derivatives in highly aqueous media. Reaction via ion pairsPaper presented in part at the Third European Symposium on Organic Reactivity (ESOR III), Goteborg, Sweden, 1991. (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 367-371 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolysis of 1,1-diphenyl-1-X-ethane (1-X) [X = 4-nitrobenzoate (PNB), 3,5-dinitrobenzoate (DNB), AcO, MeOH+, EtOH+ or H2O+] was studied in 20 vol% dimethyl sulphoxide in water, in which specific salt effects are very small, and in 25 vol% acetonitrile in water. Substrates with negatively charged leaving groups yield more elimination product 1,1-diphenylethene (3) than those with uncharged groups, indicating the intermedicacy of ion pairs. Thus, three times more alkene is formed in the reactions of the substrates 1-OAc and 1-PNB than in the acid-catalysed hydrolysis of 1-OMe and 1-OAc. The substitution products may be formed via the solvent-equilibrated carbocation since the measured nucleophilic selectivities are very similar with different leaving groups.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050614
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Oxidation of indole by N-sodio-N-chlorobenzenesulphonamide (chloramine-B) in alkaline medium catalysed by os(viii): A kinetic and mechanistic study (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 373-381 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of oxidation of indole (In) and 5-substituted indoles (OCH3, Br and Cl) by chloramine-B (CAB) were studied in alkaline medium with Os(VIII) as catalyst at 303 K. At low [In]0 the rate law rate = k [CAB] [Os(VIII)] [In]0 is obeyed, which changes to rate = k [CAB] [Os(VIII)] [OH-]-1 at higher substrate concentrations. Variation of ionic strength has no effect on the rate and the dielectric effect is negative. The reaction was studied at different temperatures and activation parameters were evaluated. Hammett correlation of substituent effects indicated a linear free energy relationship with ρ+ = - 1.0, showing the formation of an electrondeficient transition state. From enthalpy-entropy relationships and Exner correlations, the isokinetic temperature β was found to be 330 K, indicating enthalpy as a controlling factor. The mechanism assumes the formation of a complex between oxidant and Os(VIII) at high and low [In]0. Proton inventory studies in H2O-D2O mixtures showed the involvement of a single exchangeable proton of OH- ion in the transition state.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050702
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Molecular mechanics of bridged ferrocene derivatives: Conformational energy surfaces of [3]-, [4]- and [45] ferrocenophanes (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 382-394 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A molecular mechanical model is presented which allows computational interpretation of stereodynamics in ferrocenophanes by using a simple form of bending potential for angles involving the central iron atom and extended to carbon atoms of different cyclopentadienyl rings. Potential energy surfaces of [3] -, [4] - and [45] ferrocenophanes were studied in detail. For [3] ferrocenophane, the calculated energy barrier of the bridge reversal process agrees well with the experimental value. The previous interpretation of a rigid bridge in [4] ferrocenophane is questioned on the basis of the calculated low barriers. The predominance of experimentally indistinguishable enantiomeric pairs may be responsible for the misinterpretation. [45] Ferrocenophane is estimated to interconvert into D5-symmetric global energy minima over barriers of 13-15 kcal mol-1 through one-by-one flipping of five tetramethylene bridges.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050703
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Using theoretical descriptors in quantitative structure activity relationships: Some physicochemical properties (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 395-408 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The application of computational techniques to biology, chemistry and physics is growing rapidly. Quantitative structure-activity relationships (QSAR) have been used widely to relate biological activities and physicochemical properties to molecular structural features. A difficulty in this approach has been non-uniformity of parameter sets resulting in the inability to examine contributions across properties and data sets. Linear solvation energy relationships (LSER) developed by Kamlet and Taft successfully utilize a single set of parameters to correlate a wide range of biological, chemical and physical properties. The empirical LSER solvatochromic parameters have been replaced with theoretically determined parameters to permit greater ease in a priori property prediction. These TLSER descriptors have given good correlations and interpretations for some biological activities. This paper discusses the application of these descriptors to six physicochemical properties involving equilibria, kinetics and spectra. The results show good correlation and physical interpretation.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    O-17 NMR studies on α-diazoketones (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 424-428 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The O-17 NMR spectra of 13 α′-alkyl- and aryl-substituted α-diazoketones were measured. The results obtained show a clear discrimination between them. A good correlation in a series of para-substituted α-diazoacetophenones between O-17 chemical shifts and both α+p and dual substituent parameters indicated a greater contribution of resonance than inductive effects.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Kinetics of deprotonation of triphenyl(2-substituted-9-fluorenyl)phosphonium ions in 50% dimethyl sulfoxide-50% water. Intrinsic rate constants, imbalances and evidence for changes in transition state structure (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 409-423 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rate constants (kB1 and kBH-1) for the reversible deprotonation of triphenyl(2-Z-9-fluorenyl)phosphonium ions (Z = H, Br, NO2) by piperidine, morpholine, n-butylamine, 2-methoxyethylamine, glycine ethyl ester, cyanomethylamine, OH- and water were determined in 50% Me2SO-50% (v/v) water at 20°C. Brønsted αCH (variation of carbon acid) and β values (variation of amine), and intrinsic rate constants [log k0 = log kB1/q when pKBHa - pKCHa + log(p/q) = 0] were obtained. αCH decreases with increasing basicity of the amine whereas βB decreases with increasing acidity of the carbon acid. These trends, which imply changes in the transition-state structure with reactivity, can be described by the interaction coefficient pxy = ∂βB/∂pKCHa = ∂αCH/ - ∂pKBHa = 0.03 (primary amines) and 0.01 (piperidine/morpholine). αCH is smaller than βB, indicating an imbalance due to a lag in the delocalization of the negative charge into the fluorenyl moiety at the transition state. The influence of the Ph3P+ group on the intrinsic rate constant is analyzed in terms of possible contributions by inductive/field (I), resonance (R), polarizability (P) and steric (S) effects. Using 9-carbomethoxyfluorene as a reference, it is shown that the stronger electron-withdrawing I effect of the Ph3P+ group relative to the COOMe group enhances log k0 substantially; the fact that the R effect of Ph3P+ is weaker than that of COOMe also contributes to an increase in k0, and so does the P effect of the phosphorus. All these increases are virtually completely offset by the rate-retarding S effect of the bulky Ph3P+ group. A similar analysis for the Me2S+ derivative studied by Murray and Jencks [J. Am. Chem. Soc. 112, 1880 (1990)] leads to similar conclusions except that the still smaller R effect is probably one of the main reasons why k0 for the Me2S+ derivative is more than ten times higher than for the Ph3P+ derivative; another potential reason is a difference in the steric effect.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050705
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050801
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Editorial (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 435-435 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Complexes of TRI- and tetraprotonated forms of 1,4,7,10,13-pentaazacyclopentadecane with various mono- and divalent anions in aqueous media (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 443-450 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Acid dissociation and anion complexation properties of 3+ and 4+ forms of 1,4,7,10,13-pentaazacyclopentadecane were investigated by pH potentiometry, conductometric titration and 13C NMR experiments. The 3+ and 4+ species form complexes with a variety of mono- and divalent anions, and their complexation constants can be determined by pH potentiometric methods. However, no iodide complexes are detected and neither is a pentaprotonated species. Enthalpy and entropy changes for the acid dissociation of the 3+ ligand and for its complexation with chloride are estimated. The complexation and acid dissociation properties of the ligand are discussed in terms of internal hydrogen bonding interactions and solvation effects.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050804
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Potentiometric evaluation of the ion-selective characteristics of 2-borono-1,3-XYLYL crown ethers (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 437-442 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(vinyl chloride) (PVC) membranes impregnated with 2-borono-1,3-xylyl crown ethers were evaluated in ion-selective electrodes. The response pattern obtained with these crown ethers appears to be essentially independent of ring size but there is a linear correlation between selectivity and hydration enthalpy of the cation which is similar to that obtained for electrodes prepared only with the lipophilic anionic site KTCIPB. The similarities in correlation and mechanism between these two types of electrodes has been attributed to the presence of anionic sites in both cases dominating the observed selectivity. For the four ionophores considered the pH-dependent ionization of the boronate group to the boronate anion is proposed to be responsible for the domination of anionic sites on the properties of the ionophores. The ionophores proved to be good K+ neutral carriers, showing responses to this ion in the range 10-1-10-4 M. The compounds tested showed a fast response to changes in K+ concentration which was stable to within 〈 0.2 mV h-1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050803
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Alkali metal ion-assisted cleavage of crown ether anisoles by toluenethiolate anion (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 457-460 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of alkali metal ions (Li+, Na+, K+, Cs+) on the reactivity of toluenethiolate anion in the demethylation of 2-methoxy-1,3-xylyl-18-crown-5, 2-methoxy-1,3-xylyl-24-crown-7 and the model compounds anisole and 2,6-dimethylanisole was investigated in dimethylformamide (+3.3 M water) at 60°C. It was found that the metal ion effects are markedly influenced by the presence of the polyether chain in the reaction system. Whereas reactions of the model compounds are slightly inhibited by the presence of alkali metal ions, the latter strongly enhance rate of demethylation of the crown ether derivatives, the observed catalytic factors ranging over nearly three orders of magnitude. These remarkable rate-enhancing effects are ascribed to a strong transition-state stabilization by metal ions through cooperation of electrostatic binding with the negative charge developing on the oxygen atom of the methoxy group undergoing nucleophilic attack and coordinative interaction with the polyether chain.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050806
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Effect of counterion binding and alkyl chain length on the phase transition behaviour of DI-n-alkyl phosphate vesicles (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 451-456 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper describes a fluorescence depolarization and 31P NMR spectroscopic study of the phase transition behaviour of a series of identical and mixed-chain di-n-alkyl phosphate vesicles in the presence of different counterions (Na+,K+,Me4N+,Ca2+). Using trans, trans, trans-1, 6-diphenyl-1, 3, 5-hexatriene (DPH) as a fluorescent probe, the fluorescence polarization (P) was measured for the identical-chain vesicles (Na+, K+, Me4N+) as a function of temperature. The temperature for the main phase transition (Tm) only responded to variation of the counterion in the case of the longer-chain di-n-alkyl phosphates, with Tm decreasing in the sequence Na+ 〉 K+ 〉 Me4N+. This result is rationalized in terms of a decreasing counterion binding, which affects chain ordening in the core of the bilayer. Peak intensities and line widths of the 31P NMR resonances for the bilayer vesicles suggest a more complex phase behaviour, but the overall results are reconcilable with the picture emerging from the fluorescence depolarization experiments. Fluorescence depolarization measurements were also carried out with vesicles formed from the sodium di-n-alkyl phosphates and in the presence of various concentrations of Ca2+ (0-6 mM) at temperatures above Tm. For both the identical-chain and mixed-chain di-n-alkyl phosphate vesicles, a steep increase in P was found between ca 1.0 and 1.4 mM Ca2+, indicative of a strong Ca2+-induced ordening of the alkyl chains.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Survey of the DNA binding properties of natural and synthetic polyamino compounds (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 461-466 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a flourescence-detected ethidium displacement assay, the calf thymus DNA complexation properties of 27 mono-, di-, tri-, tetra- and hexacationic polyamines were determined. The DNA-binding affinity of these polyamine compounds increased with increasing cationic charge on the polyamine. Although most of the compounds exhibited no base pair binding selectivity, two of the tricationic polyamines possessing additional neutral amine groups exhibited approximately tenfold GC binding selectivities.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Modulation of the cation complexing properties in the ‘lower rim’ chemically modified calixarene series (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 496-501 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of chemical modifications on the lower rim of calix [n] arenes is analysed with respect to the cation binding ability of the receptor. Extraction data and stability constants of the complexes are discussed. Three main factors are investigated: the size of the calixarene, the conformation of the calixarene and the nature of the ligating group attached to the phenolic oxygen. The work concentrates on esters, ketones, amides, thioamides and carboxylic acids. Some data concern chemically modified tetrahomodioxacalix [4] arene esters.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050811
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Binding cooperativity in the self-assembly of double stranded silver(I) trihelicates (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 529-532 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectroscopic and potentiometric studies of Ag(I) binding by tris-bipyridine strands indicate that the formation of trinuclear silver trihelicates is a process displaying positive cooperativity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050815
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Supramolecular control of molecular electronic behaviour of TCNQ-. salts (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 533-539 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crown ether complexation of 1:1 alkali metal TCNQ salts, MTCNQ (M=K, Rb, Tl) leads to structures containing isolated TCNQ dimers. These materials provide valuable models for investigating the spectroscopic and electronic behaviour of TCNQ-. dimer components which are key structural fragments of, for example, organic metals and semiconductors.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050816
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050901
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Partial rate factors in photochemistry: The meta photocycloaddition of methylbenzenes to cyclopentene (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 581-589 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The partial rate factors of the four modes of meta photocycloaddition of methyl-substituted benzenes to cyclopentene have been determined by measuring quantum yields of formation of the most important meta photocycloadducts of benzene, toluene and the three xylenes. It is demonstrated that the results can be applied to predict quantum yields of any meta photocycloadduct of methylbenzenes to cyclopentene. The predicted yields agree very well with those determined experimentally, and it is shown that the effects of two or more methyl groups are fully additive. The method is promising for the investigation of mechanisms of photochemical reactions and can be used to predict regioselectivities.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050905
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Ionization kinetics of rhodamine b leucocyanide in the presence of poly(vinylbenzyltrimethylammonium chloride) (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 595-599 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The participation of the carboxylate group in the ionization of Rhodamine B leucocyanide was studied in an aqueous solution of poly(vinylbenzyltrimethylammonium chloride) (PVBTA) or cetyltrimethylammonium bromide (CTAB) at constant temperature and pH 8. The experimental rate constant (kexp) decreases with increasing PVBTA concentration. The results are interpreted in terms of the binding of the ionized form of Rhodamine B leucocyanide (RBCN-) to a single class of completely independent binding sites on the PVBTA. From this model, a value of 1.09 × 106 l mol-1 was obtained for the binding constant. The effect of CTAB is different from that obtained with PVBTA. After a region in which there are large changes in kexp with the CTAB concentration, this constant reaches a zone where its value is independent of the surfactant concentration. The decrease in kexp in the first zone was explained in terms of an ionic association between RBCN- and the cationic heads. In the second zone, it was assumed that a micellar effect operates on the ionization kinetics. In a similar form, the esterification of the carboxylate group leads to a slower ionization rate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050907
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Dynamic behaviour of [2] metacyclo [2] (3,4) thiophenophane (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 617-618 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational analysis of dimethyl [2] metacyclo [2] (3,4)thiophenophane (1), which is the thiophene analogue of [2.2] orthometacyclophane, is described. The comparison between the dynamic NMR spectra of 1 and the computer-simulated spectra led to the energy barrier between syn and anti conformers of 1. This is the first conformational analysis of a [2,2] orthometa-type cyclophane.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610050911
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Supramolecular metallocatalysts for the cleavage of amino acid esters (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 619-627 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transition metal ions are effective catalysts of the hydrolytic cleavage of amino acid esters and their effects can be enhanced and properly directed when they are chelated to functionalized ligands. The resulting metallocatalysts are attracting increasing attention and the systems so far investigated are briefly reviewed. Particular emphasis is given to supramolecular systems which may add to the metallocatalysts the benefits of the cooperativity, set upon convergent non-covalent interactions of their components, needed for substrate recognition. The results obtained with metallomicellar aggregates and molecular metalloreceptors, with particular reference to those studied in the authors' laboratory, are reported in more detail. In the case of loosely structured metallomicelles, remarkable accelerations and, generally, modest selectivities have been observed; less spectacular kinetic effects, but promising substrate selectivity, have been obtained with structurally well defined metalloreceptors.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051002
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    The photochemistry of pyrene-cytosine conjugates: Modelling the carcinogenic action of aromatic hydrocarbons (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 644-648 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoreduction, but not the corresponding photooxidation, of cytosine can be sensitized by a covalently appended pyrene molecule in a process that may have some importance for understanding the known carcinogenic activity of polynuclear aromatic hydrocarbons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051005
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Molecular recognition by macrocyclic receptors having multiple hydrophobic branches in a synthetic bilayer membrane (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 633-643 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hybrid molecular assemblies were prepared in combinations of a synthetic peptide lipid, involving an L-alanine residue interposed between an anionic head group and a hydrophobic double-chain segment, with cationic macrocyclic hosts, a steroid cyclophane bearing four rigid steroid moieties and octopus cyclophanes having eight flexible hydrocarbon branches. On addition of the cyclophanes to multi-walled bilayer membranes composed of the anionic lipid, thermodynamic parameters (ΔH and ΔS) associated with the phase transition between the gel and liquidcrystalline states were subjected to changes that are consistent with the formation of the hybrid assemblies. Anionic fluorescent guests, 8-anilinonaphthalene-1-sulphonate and 6-p-toluidinonaphthalene-2-sulphonate, were effectively incorporated into the hydrophobic cavities provided by the cationic cyclophanes embedded in the bilayer membrane through hydrophobic and electrostatic interactions. The guest-binding modes of the hybrid assemblies are classified into two types; a guest is included in the proximity of the hydrogen-belt domain of the bilayer membrane in one mode, and a guest is incorporated into the hydrophobic bilayer domain composed of double hydrocarbon chains of the lipid in another.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051004
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Alkaline earth metal ion catalysis of alcoholysis of crown ether aryl acetates. Effect of the base-solvent system (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 663-669 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of strontium and barium ions on the acyl transfer reaction to ethoxide ion from 2-acetoxy-1,3-xylyl-15-crown-4, 2-acetoxy-1,3-xylyl-18-crwon-5, 2-acetoxy-1,3-xylyl-21-crown-6 and the model compound phenyl acetate was investigated in ethanol at 25°C. Significant catalytic effects were observed in all of the studied reactions as a result of stronger metal ion associations with the transition states than with reactants. The rate enhancements observed with the crown ether substrates are much larger than those observed with phenyl acetate, the largest acceleration being displayed by 2-acetoxy-1,3-xylyl-21-crown-6, which reacts with EtOBaBr 5 × 105 times faster than with EtONMe4. These findings provide strong evidence that cooperation of electrostatic binding to the negative charge developing at the carbonyl oxygen and coordinative binding to the polyether chain is highly efficient in the metal-bound transition state. Comparison of rate data reported here with analogous data obtained in methanol solution clearly shows that both modes of interaction contributing to the stability of the metal-bound transition state are much more efficient in ethanol than in methanol solution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051008
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051101
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Mechanistic significance of the magnitude of cross-interaction constants (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 736-740 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationship between the magnitude of the cross-interaction constant, |ρij|, and the force constant of activation, ΔF
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Solution conformations and hydrolytic stability of 2′ - and 3′ -substituted 2′,3′-dideoxyribonucleosides, including some potential inhibitors of human immunodeficiency virus (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 741-747 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sugar ring conformations of a number of 2′ - and 3′ -substituted 2′,3′-dideoxyribonucleosides were determined in 2H2O by 1H NMR spectroscopy. First-order rate constants for the cleavage of their N-glycosidic bond in aqueous acid were measured. The dependence of sugar ring conformation and hydrolytic stability on the polar nature of the 2′/3′-substitutent is discussed.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...