全文获取类型
收费全文 | 595篇 |
免费 | 57篇 |
国内免费 | 1篇 |
出版年
2022年 | 4篇 |
2021年 | 6篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2016年 | 10篇 |
2015年 | 24篇 |
2014年 | 20篇 |
2013年 | 24篇 |
2012年 | 32篇 |
2011年 | 54篇 |
2010年 | 26篇 |
2009年 | 24篇 |
2008年 | 31篇 |
2007年 | 33篇 |
2006年 | 27篇 |
2005年 | 28篇 |
2004年 | 33篇 |
2003年 | 31篇 |
2002年 | 21篇 |
2001年 | 20篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 13篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1966年 | 2篇 |
排序方式: 共有653条查询结果,搜索用时 15 毫秒
1.
2.
3.
Evidence for a junctional feet-ryanodine receptor complex from sarcoplasmic reticulum 总被引:8,自引:0,他引:8
F A Lai H Erickson B A Block G Meissner 《Biochemical and biophysical research communications》1987,143(2):704-709
Heavy sarcoplasmic reticulum vesicles, labelled with the Ca2+ release channel probe [3H]ryanodine, were solubilized in detergent, then centrifuged through sucrose gradients. A single peak of ryanodine binding activity was observed with an apparent sedimentation coefficient of 30S. Electron microscopy of the peak fraction showed disk structures of 25-28 nm diameter and 10 nm thickness. Proteins specifically enriched in the peak fraction were the Mr 160,000 and 260,000 and junctional feet proteins (Mr 320,000 and 300,000). This suggests that the feet proteins and ryanodine receptor may be specifically associated into a large oligomeric complex comprising subunits of Mr 160,000-320,000. 相似文献
4.
Lipopolysaccharides of Thiocystis violacea, Thiocapsa pfennigii, and Chromatium tepidum, species of the family Chromatiaceae. 总被引:1,自引:0,他引:1 下载免费PDF全文
The lipopolysaccharides (LPS) of three species of purple sulfur bacteria (Chromatiaceae), Thiocystis violacea, Thiocapsa pfennigii, and the moderately thermophilic bacterium Chromatium tepidum, were isolated. The LPS of Thiocystis violacea and Chromatium tepidum contained typical O-specific sugars, indicating O-chains. Long O-chains were confirmed for these species by sodium deoxycholate gel electrophoresis of their LPS. Thiocapsa pfennigii, however, had short or no O-chains. The core region of the LPS of all three species comprised D-glycero-D-mannoheptose as the only heptose and 2-keto-3-deoxyoctonate. The lipid A, obtained from the LPS by mild acid hydrolysis, contained glucosamine as the main amino sugar. Amide-bound 3-hydroxymyristic acid was the only hydroxy fatty acid. The main ester-bound fatty acid in all lipid A fractions was 12:0. Mannose and small amounts of 2,3-diamino-2,3-dideoxy-D-glucose were common constituents of the lipid A of the three Chromatiaceae species investigated. All lipid A fractions were essentially free of phosphate. 相似文献
5.
Dibutyryl cyclic AMP triggers Ca2+ influx and Ca2+-dependent electrical activity in pancreatic B cells 总被引:2,自引:0,他引:2
In the presence of 7 mM glucose, dibutyryl cyclic AMP induced electrical activity in otherwise silent mouse pancreatic B cells. This activity was blocked by cobalt or D600, two inhibitors of Ca2+ influx. Under similar conditions, dibutyryl cyclic AMP stimulated 45Ca2+ influx (5-min uptake) in islet cells; this effect was abolished by cobalt and partially inhibited by D600. The nucleotide also accelerated 86Rb+ efflux from preloaded islets, did not modify glucose utilization and markedly increased insulin release. Its effects on release were inhibited by cobalt, but not by D600. These results show that insulin release can occur without electrical activity in B cells and suggest that cyclic AMP not only mobilizes intracellular Ca, but also facilitates Ca2+ influx in insulin secreting cells. 相似文献
6.
7.
8.
Louise Warnich Peter N. Meissner Richard J. Hift Jan H. Louw Carel J. van Heerden Andries E. Retief 《Human genetics》1996,97(5):690-692
The gene for variegate porphyria (VP), an autosomal dominant disease with a high prevalence in South Africa, evidently due
to a founder effect, was previously mapped to chromosome 14q32. In the current study this localization was evaluated by linkage
and haplotype analyses using microsatellite markers spanning a region of more than 20 cM on chromosome 14q32. In many recent
studies linkage disequilibrium between disease and marker loci has been utilized to map genes in founder populations, but
we could not find any association between VP and the markers used in this study. Our data suggest that the allocation of VP
to chromosome 14q32 may be incorrect.
Received: 1 September 1995 / Revised: 1 November 1995 相似文献
9.
Stanislaw Fedyk Wlodzimierz Chtnicki Agata Banaszek 《Evolution; international journal of organic evolution》1991,45(6):1384-1392
Two parapatric chromosomal races of the common shrew (Sorex araneus) in Poland differ in their complement of metacentric arm combinations: hk, io, gr, nm (race IV), and hi, ko, gm, np (race II). In hybrids, these eight race-diagnostic metacentrics form two randomly segregating complexes. The first complex (C1) occurs in the form of a ring configuration ok/kh/hi/io, or a chain o/ok/kh/hi/i (when there is Robertsonian polymorphism of the element io). The second complex (C2) always takes the form of a six-element chain configuration r/rg/gm/mn/np/p. The C2 complex may be shortened to five or even four elements, when acrocentrics g, m and n are present. In the contact zone we found shrews of pure races (race II or IV), as well as hybrids with C1 or C2 complexes, and recombinants hi, ko, gr, nm. Complex heterozygotes are likely to suffer reduced fertility due to malsegregation at meiosis. However, the C1 hybrids with ring configurations occur with a high frequency throughout the contact zone. This suggest that their fitness is only slightly lowered relative to pure race individuals, in contrast to the hybrids with C1 or C2 chain configurations, which presumably have a more heavily reduced fertility. On the other hand, at the center of the zone there is a high proportion of recombinants, which, being chromosomal homozygotes, should display normal meiotic segregation. Furthermore, the high frequencies of recombinants within the contact zone should facilitate gene flow between the races. The occurrence of recombinants plays a similar role as the appearance of the maximum frequencies of acrocentric homozygotes described in several contact zones of S. araneus. 相似文献
10.
Replication variants of the inactive X chromosome were investigated in lymphocytes from six donors by means of terminal BrdU or thymidine incorporation. There were interindividual differences in the incidence of particular variants. In endoreduplicated and tetraploid cells both allocyclic X chromosomes showed the same replication sequence. The Xp22 band of the allocyclic X chromosome seemed to replicate later than the homologous material in some cells. Initiation time of DNA synthesis within the inactive X chromosome was found to be stable; termination time, however, varied greatly relative to the other chromosomes. Early completion of replication within the heterochromatic X chromosome could be demonstrated preferentially for the Xq25–27 terminal sequence, but other variants expressed the phenomenon also. A variable replication rate of the inactive X chromosome is believed to be responsible for its asynchronous, independent replication. The biological significance of the phenomenon is discussed with respect to cell differentiation. 相似文献