全文获取类型
收费全文 | 2424篇 |
免费 | 267篇 |
出版年
2023年 | 17篇 |
2022年 | 12篇 |
2021年 | 65篇 |
2020年 | 31篇 |
2019年 | 43篇 |
2018年 | 51篇 |
2017年 | 42篇 |
2016年 | 84篇 |
2015年 | 159篇 |
2014年 | 159篇 |
2013年 | 151篇 |
2012年 | 229篇 |
2011年 | 185篇 |
2010年 | 120篇 |
2009年 | 102篇 |
2008年 | 135篇 |
2007年 | 157篇 |
2006年 | 131篇 |
2005年 | 140篇 |
2004年 | 106篇 |
2003年 | 99篇 |
2002年 | 115篇 |
2001年 | 23篇 |
2000年 | 16篇 |
1999年 | 21篇 |
1998年 | 23篇 |
1997年 | 14篇 |
1996年 | 23篇 |
1995年 | 12篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 5篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1974年 | 4篇 |
1973年 | 7篇 |
1970年 | 4篇 |
1969年 | 7篇 |
1962年 | 5篇 |
排序方式: 共有2691条查询结果,搜索用时 15 毫秒
1.
2.
Intestinal cholesterol absorption is specifically inhibited by the 2-azetidinone cholesterol absorption inhibitor ezetimibe. Photoreactive ezetimibe analogues specifically label a 145-kDa protein in the brush border membrane of enterocytes from rabbit small intestine identified as aminopeptidase N (CD13). In zebrafish and mouse small intestinal cytosol, a heterocomplex of Mr 52 kDa between annexin II and caveolin 1 was suggested as a target of ezetimibe. In contrast, in the cytosol and brush border membrane vesicles (BBMV) from rabbit small intestine of control animals or rabbits treated with the nonabsorbable cholesterol absorption inhibitor AVE 5530, both annexin II and caveolin 1 were exclusively present as monomers without any heterocomplex formation. Upon immunoprecipitation with annexin II a 52-kDa band was observed after immunostaining with annexin II antibodies, whereas no staining of a 52-kDa band occurred with anti-caveolin 1 antibodies. Vice versa, a 52-kDa band obtained by immunoprecipitation with caveolin 1 antibodies did not stain with annexin II-antibodies. The intensity of the 52-kDa band was dependent on the amount of antibody and was also observed with anti-actin or anti-APN antibodies suggesting that the 52-kDa band is a biochemical artefact. After incubation of cytosol or BBMV with radioactively labelled ezetimibe analogues, no significant amounts of the ezetimibe analogues could be detected in the immunoprecipitate with caveolin-1 or annexin II antibodies. Photoaffinity labelling of rabbit small intestinal BBMV with ezetimibe analogues did not result in labelling of proteins being immunoreactive with annexin II, caveolin 1 or a 52-kDa heterocomplex. These findings indicate that the rabbit small intestine does not contain an annexin II/caveolin 1 heterocomplex as a target for ezetimibe. 相似文献
3.
4.
5.
6.
Johannes Schwerk Mario K?ster Hansj?rg Hauser Manfred Rohde Marcus Fulde Mathias W. Hornef Tobias May 《PloS one》2013,8(8)
Cell lines derived from the small intestine that reflect authentic properties of the originating intestinal epithelium are of high value for studies on mucosal immunology and host microbial homeostasis. A novel immortalization procedure was applied to generate continuously proliferating cell lines from murine E19 embryonic small intestinal tissue. The obtained cell lines form a tight and polarized epithelial cell layer, display characteristic tight junction, microvilli and surface protein expression and generate increasing transepithelial electrical resistance during in vitro culture. Significant up-regulation of Cxcl2 and Cxcl5 chemokine expression upon exposure to defined microbial innate immune stimuli and endogenous cytokines is observed. Cell lines were also generated from a transgenic interferon reporter (Mx2-Luciferase) mouse, allowing reporter technology-based quantification of the cellular response to type I and III interferon. Thus, the newly created cell lines mimic properties of the natural epithelium and can be used for diverse studies including testing of the absorption of drug candidates. The reproducibility of the method to create such cell lines from wild type and transgenic mice provides a new tool to study molecular and cellular processes of the epithelial barrier. 相似文献
7.
8.
P. Higgins R. J. Mathias 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(4):439-444
Summary Calli were initiated from immature embryos of nine lines of hexaploid wheat (Triticum aestivum L. em. Thell). These were the euploid lines Chinese Spring and Cappelle-Desprez, a line of Chinese Spring ditelocentric for the long arm of 4B, four substitution lines of Chinese Spring in which chromosome 4B has been replaced by its homologues from different wheat varieties and substituted into Chinese Spring and a substitution line of Besostaya I 4B into Cappelle-Desprez. The calli from these lines were found to differ in their growth rates and morphogenic and regenerative activities. The substitution of different 4B chromosomes into Chinese Spring significantly increased morphogenesis and shoot regeneration from callus. The potential for developing wheat lines with improved culture characteristics is discussed. 相似文献
9.
Water, temperature and life 总被引:3,自引:0,他引:3
F Franks S F Mathias R H Hatley 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1990,326(1237):517-31; discussion 531-3
Cold is the fiercest and most widespread enemy of life on earth. Natural cold adaptation and survival are discussed in terms of physicochemical and biochemical water management mechanisms, relying on thermodynamic or kinetic stabilization. Distinctions are drawn between general effects of low temperature (chill) and specific effects of freezing. Freeze tolerance is a misnomer because tolerance does not extend to the cell fluids. Freezing is confined to the extracellular spaces where it acts as a means of protecting the cytoplasm against freezing injury. Freeze resistance depends on the phenomenon of undercooling, a survival mechanism that relies on the long-term maintenance of a thermodynamically highly unstable state. Correct water management involves many factors, among them the control of membrane composition and transmembrane osmotic equilibrium, the biosynthesis of compounds able to afford protection against injury through freeze desiccation and the availability (or inactivation) of biogenic ice nucleation catalysts. 相似文献
10.
Prostaglandin synthesis shows dependence on lipid hydroperoxides and resultant oxygen derived radical formation. In view of the importance of dietary copper in cytosolic copper dependent superoxide dismutase (Cu/Zn SOD) activity and the role of SOD in oxygen radical formation, the influence of dietary copper on prostacylin (PGI2) synthesis and SOD activity in rat aorta was examined. Copper deficient (0.5 micrograms Cu/g diet) rats showed a significant 47% reduction in PGI2 synthesis rates by aortic ring incubations in comparison to copper adequate (6.0 micrograms Cu/g diet) animals. Aortic SOD activity was reduced by 46% in copper deficiency in comparison to copper adequate animals. Marginal dietary copper (1.6 micrograms Cu/g diet) significantly reduced aortic SOD activity by 32% but was without effect on aortic ring incubation PGI2 synthesis. These results indicate that dietary copper deficiency, and the resultant decrease in SOD activity, depresses aortic PGI2 synthesis. 相似文献