全文获取类型
收费全文 | 696篇 |
免费 | 84篇 |
出版年
2021年 | 4篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 31篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 26篇 |
2008年 | 21篇 |
2007年 | 29篇 |
2006年 | 25篇 |
2005年 | 29篇 |
2004年 | 28篇 |
2003年 | 28篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 18篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1993年 | 12篇 |
1992年 | 15篇 |
1991年 | 22篇 |
1990年 | 12篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 17篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1905年 | 3篇 |
排序方式: 共有780条查询结果,搜索用时 15 毫秒
1.
Changes in protein phosphorylation during the cell cycle of Chinese hamster ovary cells 总被引:10,自引:0,他引:10
The phosphorylation patterns of proteins were examined during the cell cycle of Chinese hamster ovary cells. This was accomplished by labeling synchronized cells at various times with [32P]orthophosphate and separating the proteins by both isoelectric focusing and nonequilibrium pH gradient two-dimensional gel electrophoresis. The most dramatic changes occurred during late G2/M when approximately eight proteins (including vimentin, lamin B, and histones 1 and 3) showed increased phosphorylation. Ten other proteins appeared to be uniquely phosphorylated during late G2/M. Of these 10 proteins, seven were no longer phosphorylated shortly after mitosis. There is also at least one protein which showed a relative decrease in phosphorylation during late G2/M. 相似文献
2.
K. Choi M. D. Burow G. Church G. Burow A. H. Paterson C. E. Simpson J. L. Starr 《Journal of nematology》1999,31(3):283-290
Segregation of resistance to Meloidogyne arenaria in six BC₅F₂ peanut breeding populations was examined in greenhouse tests. Chi-square analysis indicated that segregation of resistance was consistent with resistance being conditioned by a single gene in three breeding populations (TP259-3, TP262-3, and TP271-2), whereas two resistance genes may be present in the breeding populations TP259-2, TP263-2, and TP268-3. Nematode development in clonally propagated lines of resistant individuals of TP262-3 and TP263-2 was compared to that of the susceptible cultivar Florunner. Juvenile nematodes readily penetrated roots of all peanut genotypes, but rate of development was slower (P = 0.05) in the resistant genotypes than in Florunner. Host cell necrosis indicative of a hypersensitive response was not consistently observed in resistant genotypes of either population. Three RFLP loci linked to resistance at distances of 4.2 to 11.0 centiMorgans were identified. Resistant and susceptible alleles for RFLP loci R2430E and R2545E were quite distinct and are useful for identifying individuals homozygous for resistance in segregating populations. 相似文献
3.
S. A. Krawetz R. A. Bricker W. Connor R. B. Church G. H. Dixon 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,75(3):402-409
Summary We have recently cloned both the bovine protamine (Krawetz et al. 1987, DNA 6: 47–57) and high mobility group (HMG-1) cDNAs (Pentecost and Dixon 1984, Bioscience Reports 4: 49–57). They have been used as probes for Restriction Fragment Length Polymorphism analysis of male-female pairs of different species and breeds, within the genus Bos. Utilizing this approach we have studied inheritance, chromosomal location and gene copy number of the bovine protamine and HMG-1 genes. This revealed that these nuclear protein genes are highly conserved suggesting that selective pressure has maintained their gene structures during evolution. A polymorphic Taq 1 restriction fragment was identified that was shown to be a heritable marker. These genes are not sex-linked and are present in a single copy for protamine and at least two copies for the HMG-1. 相似文献
4.
T Yoshikawa W Flory D H Giamalva L P Ruhr D F Church W A Pryor 《Biochemistry international》1987,15(1):147-151
Male Sprague-Dawley rats were treated ip with beta-naphthoflavone (40 mg/kg/day) in corn oil or in DMSO for three days. Diphenaldehyde (90 mg/kg in DMSO) was injected ip 24 hr after pretreatment. The increase in the levels of aspartate aminotransferase, alanine aminotransferase, sorbitol dehydrogenase, gamma glutamyl transpeptidase, and lactate dehydrogenase was significantly lower in rats pretreated with BNF. This suggests that the BNF-induced P-450 isozyme systems have a protective effect against the acute hepatotoxicity of diphenaldehyde. 相似文献
5.
L D Foil T R Klei R I Miller G E Church C S Foil D D French J N Smith 《The Journal of parasitology》1987,73(2):320-326
Seasonal changes in density and spatial distribution of Onchocerca cervicalis microfilariae were studied in ventral-midline skin of 15 infected pony mares in southern Louisiana. Triple running mean analysis of data over a 13-mo period indicated that a distinct pattern exists in total microfilariae population density and in microfilariae occurrence in different levels of the dermis. Microfilariae density reaches peak levels in the spring followed by a 58% decrease in the summer, a 19% increase in the fall, and a decrease to the lowest numbers in the winter. Microfilariae were found in all levels of the skin during the spring, summer, and fall but were not found in the superficial layers of the dermis during the winter months. The population density of Culicoides variipennis, a demonstrated vector of O. cervicalis, appeared to have seasonal fluctuations similar to the changes in microfilarial density. Harmonic wave analysis of microfilariae density data in individual ponies showed that all individuals did not follow the population trend. 相似文献
6.
Evolution of the 28S ribosomal RNA gene in anurans: regions of variability and their phylogenetic implications 总被引:1,自引:0,他引:1
Fifteen restriction sites were mapped to the 28S ribosomal RNA gene of
individuals representing 54 species of frogs, two species of salamanders, a
caecilian, and a lungfish. Eight of these sites were present in all species
examined, and two were found in all but one species. Alignment of these
conserved restriction sites revealed, among anuran 28S rRNA genes, five
regions of major length variation that correspond to four of 12 previously
identified divergent domains of this gene. One of the divergent domains
(DD8) consists of two regions of length variation separated by a short
segment that is conserved at least throughout tetrapods. Most of the
insertions, deletions, and restriction-site variations identified in the
28S gene will require sequence-level analysis for a detailed reconstruction
of their history. However, an insertion in DD9 that is coextensive with
frogs in the suborder Neobatrachia, a BstEII site that is limited to
representatives of two leptodactylid subfamilies, and a deletion in DD10
that is found only in three ranoid genera are probably synapomorphies.
相似文献
7.
8.
9.
T Yoshikawa W Flory D H Giamalva L P Ruhr D F Church W A Pryor 《Biochemistry international》1988,16(5):929-934
Male Sprague-Dawley rats were pretreated i.p. with corn oil or DMSO (1.5 ml/kg/day), or with beta-naphthoflavone (BNF, 40 mg/kg/day) in corn oil or DMSO for 3 days. 1-Nitropyrene (1-NP, 150 mg/kg) in DMSO was injected i.p. 24 hr after pretreatment. A significant increase in the levels of several serum enzymes was seen in rats pretreated with corn oil alone 24 hr after 1-NP injection. The increase in enzyme activities was significantly reduced by a 3-day pretreatment with DMSO or BNF. 相似文献
10.
Characterization of cross-bridge elasticity and kinetics of cross-bridge cycling during force development in single smooth muscle cells 总被引:4,自引:2,他引:2 下载免费PDF全文
Force development in smooth muscle, as in skeletal muscle, is believed to reflect recruitment of force-generating myosin cross-bridges. However, little is known about the events underlying cross-bridge recruitment as the muscle cell approaches peak isometric force and then enters a period of tension maintenance. In the present studies on single smooth muscle cells isolated from the toad (Bufo marinus) stomach muscularis, active muscle stiffness, calculated from the force response to small sinusoidal length changes (0.5% cell length, 250 Hz), was utilized to estimate the relative number of attached cross-bridges. By comparing stiffness during initial force development to stiffness during force redevelopment immediately after a quick release imposed at peak force, we propose that the instantaneous active stiffness of the cell reflects both a linearly elastic cross-bridge element having 1.5 times the compliance of the cross-bridge in frog skeletal muscle and a series elastic component having an exponential length-force relationship. At the onset of force development, the ratio of stiffness to force was 2.5 times greater than at peak isometric force. These data suggest that, upon activation, cross-bridges attach in at least two states (i.e., low-force-producing and high-force-producing) and redistribute to a steady state distribution at peak isometric force. The possibility that the cross-bridge cycling rate was modulated with time was also investigated by analyzing the time course of tension recovery to small, rapid step length changes (0.5% cell length in 2.5 ms) imposed during initial force development, at peak force, and after 15 s of tension maintenance. The rate of tension recovery slowed continuously throughout force development following activation and slowed further as force was maintained. Our results suggest that the kinetics of force production in smooth muscle may involve a redistribution of cross-bridge populations between two attached states and that the average cycling rate of these cross-bridges becomes slower with time during contraction. 相似文献