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排序方式: 共有971条查询结果,搜索用时 593 毫秒
261.
Two new cytotoxic antitumor diterpenoids of the cembrane class, named 14-deoxycrassin (3) and pseudoplexaurol (4), have been isolated from the Caribbean gorgonian octocoralPseudoplexaura porosa. The structure of lactone3, possessing the infrequently encountered -methylene--lactone ring, has been established from spectral and chemical data and that of alcohol4 has been established from spectral data. 相似文献
262.
J. Zídková V. Větvička P. Rossmann V. Dlabač J. Stránsky 《Cellular and molecular life sciences : CMLS》1984,40(9):975-977
Summary The third component of the pig complement system (C3) was isolated in hemolytically active form and characterized. The C3 component is a -globulin with the molecular weight of 191,000 and is composed of 2 non-identical polypeptide chains of Mt 112,000 and 74,000. The isolated C3 can be used for the detection of the C3b receptor on the membranes of heterologous peritoneal macrophages. 相似文献
263.
R. Díaz de la Guardia L. Pascual J. C. Orozco 《Cellular and molecular life sciences : CMLS》1979,35(6):741-742
Summary The karyotype ofMicrotus cabrerae, a species endemic to Spain, is described. It comprises 2n=54 chromosomes, with a fundamental number of 64, and with very large sex chromosomes. An evolutionary relationship between this species andM. chrotorrhinus is suggested. 相似文献
264.
Myoplasmic calcium transients in response to pulse depolarisations have been monitored using the dye antipyralazo III, which provides a linear measure of the change in cytoplasmic free calcium concentration. Intramembrane charge movements were recorded simultaneously with the calcium transients. Except for its initial phase, the calcium transient during each pulse closely followed the time course expected for calcium redistribution between three intracellular compartments with time-independent flux coefficients. The time at which the flux coefficients attained their steady values occurred just after the intramembrane charge movement had been completed. This is the required sequence if charge movement were to control one or more coefficients f or calcium fluxes across the sarcoplasmic reliculum membrane. 相似文献
265.
A. G. Del Río 《Cellular and molecular life sciences : CMLS》1979,35(2):185-186
Summary
Bufo arenarum spermatozoa were able to sustain motility both under aerobic and anaerobic conditions. In aerobiosis, the oxygen consumption varies between 2.6 and 4.2 l O2/108 cells/h at 30°C. The synthesis of lactic acid by anaerobic spermatozoa demonstrated the existence of an active glycolytic pathway.This work was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas and the Latinoamerican Program of Human Reproduction (PLAMIRH), grant 34-95-2-75. 相似文献
266.
A. Bukovský J. Presl Z. Krabec T. Bednařík 《Cellular and molecular life sciences : CMLS》1977,33(2):280-281
Summary Intraperitoneal treatment of adult rats with antithymocyte serum for 2 weeks altered the ovarian function. During the treatment, anovulation with the persistence of corpora lutea and a tendency toward a permanent diestrous state was observed. 相似文献
267.
J. Puente A. M. Martínez G. Beckhaus M. Sapag-Hagar 《Cellular and molecular life sciences : CMLS》1981,37(5):459-460
Summary -Glutamyltranspeptidase activity and glutathione levels were studied in rat mammary gland during the lactogenic cycle; both increased during mid-lactation. The enzyme's specific activity with several amino acids showed that glutamine and methionine were the best substrates. Maleate decreased the transpeptidation reaction and increased the hydrolytic activity. These results suggest that -glutamyltranspeptidase from the mammary gland is similar to the enzyme described in other tissues in relation to these properties and the physiological role proposed in amino acids transport. 相似文献
268.
Jiang Hui 《科学通报(英文版)》2007,52(6):789-796
Diatom data from core MD992271 on the North Icelandic shelf record a cooling trend through the last 3000 years. This is indicated by a general decrease in warm water species and an increase in cold water taxa. The relative abundance of these two diatom groups changed periodically, suggesting that the climate also fluctuated within this time period. The results of diatom-based transfer function calculation show that the summer sea-surface temperatures (SSTs) before 1400 cal. a BP were generally higher than the mean value for the last 3000 years and the summer SSTs fluctuated around the mean between 1400 and 700 cal. a BP, and dropped to the values below the mean after 700 cal. a BP. Four cooling events were distinguished, centered at around 2600, 1900, 1300 and 600 cal. a BP respectively. The results are not only consistent with the data from neighbouring cores HM107-03 and MD992275, but also comparable with those from the GISP2 ice core and from other marine sediment records in the North Atlantic. This suggests that changes in the summer SSTs reflect regional climate variations in the North Atlantic. On the North Icelandic shelf, the summer SST variation is a result of changes in the in-teraction between the cold and the warm currents in the area. 相似文献
269.
Tímea Szederjesi Tomáš Pavlíček Orsolya Márton Virág Krízsik Csaba Csuzdi 《Journal of Natural History》2019,53(5-6):301-314
Dendrobaena veneta is one of the most widely used compost worms now distributed all over Europe and has been described under several synonymous names. Besides the typical stripy red specimens, another form bearing pinkish pigmentation also exists, mostly found in natural habitats in the East Mediterranean. Here we provide the first integrative taxonomic analysis of D. veneta, including some closely related species. Both the morphological and molecular results highly support the resurrection of D. succinta, a former synonym of D. veneta. In addition, we describe a peculiar new species, D. karacadagi sp. n. from Anatolia, and prove the highly homoplasious character of the cross section of the longitudinal musculature.
urn:lsid:zoobank.org:pub:336D3F7A-AEA1-465B-9096-03070C761A6A 相似文献
270.
Fernando Bartolomé Úrsula Muñoz Noemí Esteras Carolina Alquezar Andrea Collado Félix Bermejo-Pareja Ángeles Martín-Requero 《Cellular and molecular life sciences : CMLS》2010,67(24):4257-4268
Statins may exert beneficial effects on Alzheimer’s disease (AD) patients. Based on the antineoplastic and apoptotic effects
of statins in a number of cell types, we hypothesized that statins may be able to protect neurons by controlling the regulation
of cell cycle and/or apoptosis. A growing body of evidence indicates that neurodegeneration involves the cell-cycle activation
in postmitotic neurons. Failure of cell-cycle control is not restricted to neurons in AD patients, but occurs in peripheral
cells as well. For these reasons, we studied the role of simvastatin (SIM) on cell survival/death in lymphoblasts from AD
patients. We report here that SIM induces apoptosis in AD lymphoblasts deprived of serum. SIM interacts with PI3K/Akt and
ERK1/2 signaling pathways thereby decreasing the serum withdrawal-enhanced levels of the CDK inhibitor p21Cip1 (p21) and restoring the vulnerability of AD cells to trophic factor deprivation. 相似文献