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   20901篇
  免费   1733篇
  国内免费   1341篇
  23975篇
  2024年   52篇
  2023年   250篇
  2022年   542篇
  2021年   883篇
  2020年   709篇
  2019年   811篇
  2018年   847篇
  2017年   667篇
  2016年   905篇
  2015年   1360篇
  2014年   1610篇
  2013年   1664篇
  2012年   1960篇
  2011年   1798篇
  2010年   1190篇
  2009年   976篇
  2008年   1137篇
  2007年   1002篇
  2006年   963篇
  2005年   802篇
  2004年   679篇
  2003年   691篇
  2002年   538篇
  2001年   278篇
  2000年   249篇
  1999年   236篇
  1998年   166篇
  1997年   130篇
  1996年   126篇
  1995年   122篇
  1994年   103篇
  1993年   66篇
  1992年   84篇
  1991年   73篇
  1990年   63篇
  1989年   49篇
  1988年   34篇
  1987年   25篇
  1986年   37篇
  1985年   33篇
  1984年   19篇
  1983年   8篇
  1982年   10篇
  1981年   5篇
  1980年   3篇
  1979年   3篇
  1976年   3篇
  1972年   2篇
  1971年   2篇
  1962年   2篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
Dong YN  Mao MH  Wang XM  Han JS 《生理学报》1998,50(6):663-670
西方采用放射配体结合实验研究了100HZ电针耐受发生发展过程中大鼠脑和脊髓K受体结构特性的变化。大鼠每天给予100HZ电针1次,连续7d。分别在电针的第1、3、5、7天取不同脑区进行观察。  相似文献   
112.
113.
IL-35 subunit EBI3 is up-regulated in pulmonary fibrosis tissues. In this study, we investigated the pathological role of EBI3 in pulmonary fibrosis and dissected the underlying molecular mechanism. Bleomycin-induced pulmonary fibrosis mouse model was established, and samples were performed gene expression analyses through RNAseq, qRT-PCR and Western blot. Wild type and EBI3 knockout mice were exposed to bleomycin to investigate the pathological role of IL-35, via lung function and gene expression analyses. Primary lung epithelial cells were used to dissect the regulatory mechanism of EBI3 on STAT1/STAT4 and STAT3. IL-35 was elevated in both human and mouse with pulmonary fibrosis. EBI3 knockdown aggravated the symptoms of pulmonary fibrosis in mice. EBI3 deficiency enhanced the expressions of fibrotic and extracellular matrix-associated genes. Mechanistically, IL-35 activated STAT1 and STAT4, which in turn suppressed DNA enrichment of STAT3 and inhibited the fibrosis process. IL-35 might be one of the potential therapeutic targets for bleomycin-induced pulmonary fibrosis.  相似文献   
114.
川鄂山茱萸不同部位中熊果酸的含量测定   总被引:2,自引:0,他引:2  
目的:测定川鄂山茱萸不同部位中熊果酸的含量,筛选含量最高的部位,为充分利用川鄂山茱萸野生资源提供依据。方法:采用SymmetrySheild TM RP18色谱柱4.6mm×250mm,5μm);乙腈-水-磷酸(80∶20∶0.1)为流动相;检测波长为206nm;流速为1.0mL/min;柱温为30℃。结果:熊果酸在0.42mg~2.94mg范围内呈良好的线性关系(r=0.9998),平均回收率为96.27%,RSD为1.4%。结论:川鄂山茱萸不同部位均含有熊果酸,且含量有明显差别。川鄂山茱萸总苞片的熊果酸含量为1.1044%,有一定的开发价值。  相似文献   
115.
Endostatin promotes the anabolic program of rabbit chondrocyte   总被引:3,自引:0,他引:3  
Feng Y  Wu YP  Zhu XD  Zhang YH  Ma QJ 《Cell research》2005,15(3):201-206
  相似文献   
116.
117.
118.
Sphingosine-1-phosphate (S1P) is considered to be an important regulator of diverse biological processes acting as a natural ligand to EDG receptors. As a preliminary study to develop potent and selective agonist and antagonist for EDG receptors, we report synthesis of S1P stereoisomers and analogues and their binding affinities to EDG-1, -3, and -5.  相似文献   
119.
An all solid state potentiometric immunosensor (ASPI) has been developed to study the activation process of neuronal nitric oxide synthase (nNOS), the enzyme involved in the synthesis of nitric oxide generated under physiological conditions. At first, an all solid state H+-selective ISE was fabricated with the carboxylated poly(vinyl chloride) (PVC-COOH) film containing H+ ionophore, antibody was then immobilized on the polymer layer. The immunocomplex formation was detected by monitoring pH change due to interaction between urease labeled secondary antibody and antigen. Experimental parameters such as the amount of phosphorylated nNOS immobilized on the electrode surface and pH responses due to the antibody–antigen reaction were studied in detail. The calibration plot of the potentiometric potential vs. phosphorylated nNOS concentration exhibited a linear relationship in the range of 3.4–340.0 μg/ml. The calibration sensitivity of the phosphorylated nNOS immunosensor was −0.073 ± 0.002 mV/μg ml−1. The detection limit of nNOS was determined to be 0.2 μg/ml based on five-time measurements (95% confidence level, k = 3, n = 5). The reliability of the immunosensor was examined with rat brain tissues as well as neuronal cells, and the results shown were good, implying a promising approach for a novel electrochemical immunosensor platform with potential applications to clinical diagnosis.  相似文献   
120.
Similarities between age-related changes in the canine and human brain have resulted in the general acceptance of the canine brain as a model of human brain aging. The hippocampus is essentially required for intact cognitive ability and appears to be particularly vulnerable to the aging process. We observed changes in ionized calcium-binding adapter molecule 1 (Iba-1, a microglial marker) immunoreactivity and protein levels in the hippocampal dentate gyrus and CA1 region of adult (2-3 years) and aged (10-12 years) dogs. We also observed the interferon-gamma (IFN-gamma), a pro-inflammatory cytokine, protein levels in these groups. In the dentate gyrus and CA1 region of the adult dog, Iba-1 immunoreactive microglia were well distributed and their processes were highly ramified. However, in the aged dog, the processes of Iba-1 immunoreactive microglia were hypertrophied in the dentate gyrus. Moreover, Iba-1 protein level in the dentate gyrus in the aged dog was higher than in the adult dog. IFN-gamma expression was increased in the dentate gyrus homogenates of aged dogs than adult dogs. In addition, we found that some neurons were positive to Fluoro-Jade B (a marker for neuronal degeneration) in the dentate polymorphic layer, but not in the hippocampal CA1 region in the aged dog. These results suggest that Iba-1 immunoreactive microglia are hypertrophied in the dentate gyrus in the aged dog.  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