首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1756篇
  免费   150篇
  国内免费   2篇
  2022年   12篇
  2021年   37篇
  2020年   17篇
  2019年   24篇
  2018年   36篇
  2017年   29篇
  2016年   44篇
  2015年   75篇
  2014年   85篇
  2013年   107篇
  2012年   127篇
  2011年   121篇
  2010年   81篇
  2009年   67篇
  2008年   92篇
  2007年   94篇
  2006年   81篇
  2005年   77篇
  2004年   76篇
  2003年   76篇
  2002年   74篇
  2001年   17篇
  2000年   20篇
  1999年   21篇
  1998年   25篇
  1997年   14篇
  1996年   12篇
  1995年   15篇
  1994年   9篇
  1993年   19篇
  1992年   15篇
  1991年   11篇
  1990年   14篇
  1989年   7篇
  1988年   9篇
  1987年   14篇
  1986年   11篇
  1985年   12篇
  1984年   16篇
  1983年   20篇
  1982年   14篇
  1981年   11篇
  1980年   17篇
  1979年   7篇
  1978年   7篇
  1977年   11篇
  1976年   10篇
  1974年   7篇
  1973年   7篇
  1964年   6篇
排序方式: 共有1908条查询结果,搜索用时 15 毫秒
91.

Background  

Involvement of conservative molecular modules and cellular mechanisms in the widely diversified processes of eukaryotic cell morphogenesis leads to the intriguing question: how do similar proteins contribute to dissimilar morphogenetic outputs. Formins (FH2 proteins) play a central part in the control of actin organization and dynamics, providing a good example of evolutionarily versatile use of a conserved protein domain in the context of a variety of lineage-specific structural and signalling interactions.  相似文献   
92.
93.
High-resolution (500 MHz) multiresonance/multinuclear proton (1H) nuclear magnetic resonance (NMR) spectroscopy was used to detect metabolic changes and cellular injury in the rat brain stem and spinal cord following chronic morphine treatment. Compensatory changes were observed in glycine, glutamate, and inositols in the brain stem, but not the spinal cord, of chronic morphine-treated rats. In spinal cord, increases were detected in lactate and N-acetyl-aspartate (NAA), suggesting that there is anaerobic glycolysis, plasma membrane damage, and altered pH preferentially in the spinal cord of chronic morphine-treated rats.  相似文献   
94.
HDL subspecies Lp(A-I) and Lp(A-I,A-II) have different anti-atherogenic potentials. To determine the role of lipoprotein lipase (LPL) and hepatic lipase (HL) in regulating these particles, we measured these enzyme activities in 28 healthy subjects with well-controlled Type 1 diabetes, and studied their relationship with Lp(A-I) and Lp(A-I,A-II). LPL was positively correlated with the apolipoprotein A-I (apoA-I), cholesterol, and phospholipid mass in total Lp(A-I), and with the apoA-I in large Lp(A-I) (r >or= 0.58, P >or= 0.001). HL was negatively correlated with all the above Lp(A-I) parameters plus Lp(A-I) triglyceride (r >or= -0.53, P or= 0.50, P 相似文献   
95.
Oxidative stress and resulting lipid peroxidation are important risk factors for dietary-associated colon cancer. To get a better understanding of the underlying molecular mechanisms, we need to characterise the risk potential of the key compounds, which cause DNA damage in cancer-relevant genes and especially in human target cells. Here, we investigated the genotoxic effects of 4-hydroxy-2-nonenal (HNE) and hydrogen peroxide (H(2)O(2)) in human colon cells (LT97). LT97 is a recently established cell line from a differentiated microadenoma and represents cells from frequent preneoplastic lesions of the colon. The genomic characterisation of LT97 was performed with 24-colour FISH. Genotoxicity was determined with single cell microgelelectrophoresis (Comet assay). Comet FISH was used to study the sensitivity of TP53-a crucial target gene for the transition of adenoma to carcinoma-towards HNE. Expression of glutathione S-transferases (GST), which deactivates HNE, was determined as GST activity and GSTP1 protein levels. LT97 cells were compared to primary human colon cells and to a differentiated clone of HT29. Karyotyping revealed that the LT97 cell line had a stable karyotype with only two clones, each containing a translocation t(7;17) and one aberrant chromosome 1. The Comet assay experiments showed that both HNE and H(2)O(2) were clearly genotoxic in the different human colon cells. HNE was more genotoxic in LT97 than in HT29clone19A and primary human colon cells. After HNE incubation, TP53 migrated more efficiently into the comet tail than the global DNA, which suggests a higher susceptibility of the TP53 gene to HNE. GST expression was significantly lower in LT97 than in HT29clone19A cells, which could explain the higher genotoxicity of HNE in the colon adenoma cells. In conclusion, the LT97 is a relevant model for studying genotoxicity of colon cancer risk factors since colon adenoma are common preneoplastic lesions occurring in advanced age.  相似文献   
96.
The mitogen-stimulated protein kinase p70(s6k)/p85(s6k) (S6K) plays an essential role in cell proliferation and growth, with inhibitors of the S6K signalling pathway showing promise as anti-tumour therapeutics. Here, we report that the bisindolylmaleimide derivative Ro 31-6045, previously reported to be inactive as a kinase inhibitor, inhibited S6K activity in vivo with an IC50=8 microM. Structure/function analysis using mutant forms of S6K indicates that Ro 31-6045 inhibition is independent of the upstream activator mTOR. Ro 31-6045 will prove useful in elucidating the complex activation mechanism of S6K and its independence from mTOR will allow confirmation of functional data obtained using the mTOR inhibitor rapamycin.  相似文献   
97.
Vaccine-induced cytotoxic T lymphocytes (CTL) have been implicated in the control of virus replication in simian immunodeficiency virus (SIV)-challenged and simian-human immunodeficiency virus-challenged macaques. Therefore, we wanted to test the impact that vaccine-induced CTL responses against an immunodominant Gag epitope might have in the absence of other immune responses. By themselves, these strong CTL responses failed to control SIVmac239 replication.  相似文献   
98.
The regulatory proteins of human immunodeficiency virus may represent important vaccine targets. Here we assessed the role of Tat-specific cytotoxic T lymphocytes (CTL) in controlling pathogenic simian immunodeficiency virus SIVmac239 replication after using a DNA-prime, vaccinia virus Ankara-boost vaccine regimen. Despite the induction of Tat-specific CTL, there was no significant reduction in either peak or viral set point compared to that of controls.  相似文献   
99.
100.
The aim of this investigation was to establish the impact of phage therapy on the turnover and function of circulating neutrophils in 37 patients with suppurative bacterial infections. We determined the levels of circulating neutrophils and their precursors before therapy, after 3 weeks of therapy, and at a distant time interval (3 months) following the beginning of therapy. In addition, we measured the ability of neutrophils to phagocytize Staphylococcus aureus in vitro. Eight healthy blood donors served as a control group. The results showed that, among the studied parameters, the significant changes involved neutrophil precursor count and the ability of neutrophils to phagocytize bacteria. The percentage of neutrophils in patients before therapy was lower than in healthy donors (mean 58.0, versus 61.4). This value dropped further in patients after 3 months of following the therapy (mean 55.6). The content of neutrophil precursors, on the other hand, was lower in healthy donors than in patients before therapy (mean 2.5, versus 3.8). After 3 weeks of the therapy and after 3 months, the levels of neutrophil precursors were significantly higher (mean 4.8 and 4.9, respectively) than in control donors. The phagocytic index was lower in patients before therapy than in control donors (mean 66.3, versus 70.1) and decreased further after 3 weeks of therapy (mean 59.0) and after 3 months (mean 59.6). The results of this investigation indicate that successful phage therapy accelerates the turnover of neutrophils, accompanied by a decrease in their ability to phagocytize bacteria.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号