全文获取类型
收费全文 | 815篇 |
免费 | 38篇 |
出版年
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 28篇 |
2014年 | 35篇 |
2013年 | 44篇 |
2012年 | 66篇 |
2011年 | 56篇 |
2010年 | 35篇 |
2009年 | 22篇 |
2008年 | 44篇 |
2007年 | 50篇 |
2006年 | 39篇 |
2005年 | 42篇 |
2004年 | 38篇 |
2003年 | 30篇 |
2002年 | 36篇 |
2001年 | 21篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1992年 | 5篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 8篇 |
1967年 | 5篇 |
1966年 | 6篇 |
1965年 | 3篇 |
排序方式: 共有853条查询结果,搜索用时 31 毫秒
171.
In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli, both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag(+) (in the form of AgNO(3)). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli. 相似文献
172.
Kappa 阿片受体的抗缺血性心脏保护作用--信息机制 总被引:7,自引:0,他引:7
有证据表明,心脏细胞产生强腓肽和强腓肽类多肽,它们是kappa阿片受体(κ-0R)的激动剂。κ-0R是心脏一种优势的阿片受体,其激活可改变在体和离体心脏的功能。在正常和病理情况下,内源性κ-阿片肽可能通过自分泌或旁分泌的方式调节心脏功能。心肌缺血是导致心脏功能紊乱的一个常见原因,主要表现为心肌功能减弱,心律失常及心肌梗塞等。心肌缺血时,交感神经发放增强,从而增加作功负荷及氧消耗量;而这又使缺血引发的状况更为恶化。机体抵抗缺血引发心肌损害/心律失常的保护机制之一是抑制β-肾上腺素受体(β—AR)的兴奋。κ-0R确实能抑制β-AR的激动。这种抑制主要是由于GS蛋白受到抑制,也在较小程度上由于信息通路的腺苷酸环化酶的抑制。因为该种酶能通过对百日咳毒素敏感的G蛋白转导β—AR的激动。另一保护心肌对抗缺血性损害的机制是预处理。预处理是指预先受到缺血等损伤使心脏对随后更严重的损伤产生较强的耐受能力。这种保护作用可以在预处理后即时产生,也可延至预处理后1—3天。在采用缺血或其产生的后果之一——代谢抑制作为预处理而致的心脏保护中,κ-OR参与媒介预处理的作用。用κ—OR的特异性激动剂U50488H激活κ—OR(U50488H药理性预处理,UP)可激活蛋白激酶C(PKC),开放ATY敏感的钾通道(KATP channels)及增加热休克蛋白(HSP)的产生。阻断PKC的作用,关闭KATP通道或抑制HSP的合成,均可消除UP的心脏保护作用。这些发现表明,PKC、KATP通道和HSP在UP的心脏保护中均具重要作用。此外,UP也能减低缺血造成心肌损害的因素之一,即Ca^2 的超负荷。这个事实表明UP发挥心脏保护作用至少部分地是通过减低Ca^2 的超负荷。最有趣的是,以阻断剂阻塞KATP通道,在消除UP的延迟性心脏保护作用的同时也降低了UP对Ca^2 超负荷的抑制作用。这个事实揭示了KATP通道开放所致的心脏保护作用至少部分地可能是由于防止或减低了Ca^2 的超负荷。 相似文献
173.
Ivana Valachová Jana Bohová Zuzana Pálošová Peter Takáč Milan Kozánek Juraj Majtán 《Cell and tissue research》2013,353(1):165-171
Lucifensin, a novel larval defensin, is one of the antibacterial agents of medicinal maggots involved in maggot therapy. The goal of this study was to examine lucifensin expression in various larval tissues during Lucilia sericata development and in maggots exposed to a variety of infectious environments in vitro. In situ hybridisation revealed lucifensin expression in the salivary glands of all larval stages. Expression was occasionally detected in a few cells of the fat body and in the grease coupler of the salivary glands. Expression of lucifensin in the salivary glands was initiated 5–6 h after hatching from the egg. Maximum expression was reached about 24 h after hatching, remained strong during the second and third instars and declined at the end of the third instar, before the wandering stage. Expression of lucifensin was also investigated in maggots after oral ingestion of certain pathogens regularly found in infected chronic wounds. No differences were detected in the salivary glands after stimulation by wound bacterial isolates. However, lucifensin expression was strongly stimulated in the fat body by the presence of Staphylococcus aureus and Pseudomonas aeruginosa. Our data suggest that certain infectious environments increase lucifensin expression only in the fat body, whereas its production and antimicrobial activity in excretion/secretion products are not affected. 相似文献
174.
The circulation in anaesthetized rats with Yoshida ascites tumour was studied. Cardiac output was determined according to the reference flow method, while the distribution of cardiac output by labelled microspheres 15 mu in diameter. Arterial blood pressure decreased by 39 mm Hg and TPR by 23% at unaltered cardiac output. Blood flow of the brain and the coronaries increased by 39-43% while that of the kidney and the intestines decreased by 43 and 28%, respectively. The cardiac output fractions of the brain, the coronaries and the hepatic artery increased considerably, while that of the kidney decreased. The haematocrit decreased from 43 to 23%. It is assumed that part of the circulatory alterations (redistribution of cardiac output) were due to the anaemia and its consequences, while the others (arterial hypotension, lack of increase in cardiac output) should be regarded as an effect of a factor reaching the circulation from the cells of the ascites tumour. 相似文献
175.
L A Bristol K Sakaguchi E Appella D Doyle L Takács 《Journal of immunology (Baltimore, Md. : 1950)》1992,149(2):367-372
The rat thymocyte costimulating protein appears to be involved in the regulation of CD4-/CD8- thymocyte proliferation in vitro. We show that thymocyte costimulating protein is dipeptidyl peptidase IV (E.C.N.3.4.14.5) also known as CD26. Some bone marrow cells as well as CD4-/CD8- and, and to a lesser extent, more differentiated T cells respond by proliferating to a CD26 specific mAb-mediated costimulus that does not influence dipeptidyl dipeptidase IV enzyme activity. This suggests the existence of a CD26-linked regulatory mechanism of proliferation that is operational on granulocyte- and macrophage-lineage cells and throughout T cell development. 相似文献
176.
Dr. Á. Szél L. Takács É. Monostori I. Vigh-Teichmann P. Röhlich 《Cell and tissue research》1985,240(3):735-741
Summary Immune cells producing antibodies to chicken photoreceptor membranes were fused with myeloma cells and supernatants of the resulting hybridoma cells were used to test various types of photoreceptor cells in the chicken retina by means of immunocytochemistry. A polyclonal antibody raised against the protein component of bovine rhodopsin was also used.Outer segments of various photoreceptor cells were labelled by the following antibodies: rods were positive with the anti-rhodopsin antibody, both members of the double cones were stained by supernatant A1, while one type of single cones (designated as type A) was specifically labelled by supernatants A5, B3 and D6. The other type of single cones (type B) reacted with anti-rhodopsin and supernatant A1. The results indicate that there are distinct differences in the molecular structure of various photoreceptor outer segments. 相似文献
177.
178.
The xenoestrogens biphenol‐A and nonylphenol differentially regulate metalloprotease‐mediated shedding of EGFR ligands
下载免费PDF全文
![点击此处可从《Journal of cellular physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
179.
Verheggen MM Bont HI Adriaansen-Soeting PW Goense BJ Tak CJ Hoogsteden HC Hal PT Versnel MA 《Mediators of inflammation》1996,5(3):210-217
In this study, we investigated the expression of lipocortin I and II (annexin I and I in the human bronchial epithelium, both in vivo and in vitro. A clear expression of lipocortin I and II protein was found in the epithelium in sections of bronchial tissue. In cultured human bronchial epithelial cells we demonstrated the expression of lipocortin I and II mRNA and protein using Northern blotting, FACScan analysis and ELISA. No induction of lipocortin I or II mRNA or protein was observed after incubation with dexamethasone. Stimulation of bronchial epithelial cells with IL-1beta, TNF-alpha or LPS for 24 h did not affect the lipocortin I or II mRNA or protein expression, although PGE(2) and 6-keto-PGF(1alpha) production was significantly increased. This IL-1beta- and LPS-mediated increase in eicosanoids could be reduced by dexamethasone, but was not accompanied by an increase in lipocortin I or II expression. In human bronchial epithelial cells this particular glucocorticoid action is not mediated through lipocortin I or II induction. 相似文献
180.
S. C. Nair P. M. J. Welsing I. Y. K. Choi J. Roth D. Holzinger J. W. J. Bijlsma J. M. van Laar D. M. Gerlag F. P. J. G. Lafeber P. P. Tak 《PloS one》2016,11(3)