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   1007篇
  免费   53篇
  2023年   4篇
  2022年   4篇
  2021年   12篇
  2020年   14篇
  2019年   11篇
  2018年   17篇
  2017年   13篇
  2016年   20篇
  2015年   28篇
  2014年   35篇
  2013年   51篇
  2012年   67篇
  2011年   65篇
  2010年   39篇
  2009年   37篇
  2008年   69篇
  2007年   74篇
  2006年   69篇
  2005年   70篇
  2004年   85篇
  2003年   71篇
  2002年   58篇
  2001年   14篇
  2000年   13篇
  1999年   16篇
  1998年   4篇
  1997年   14篇
  1996年   11篇
  1995年   11篇
  1994年   7篇
  1993年   6篇
  1992年   3篇
  1991年   6篇
  1990年   6篇
  1989年   4篇
  1988年   2篇
  1987年   6篇
  1986年   5篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   4篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有1060条查询结果,搜索用时 890 毫秒
21.
22.
Summary Insitu perfusion of rat liver was performed with a medium containing glucose-cysteine adduct [2-(D-gluco-pentahydroxypentyl) thiazolidine-4-carboxylic acid, glc-cys] and its effect on glutathione (GSH) and ATP levels and bile production was examined. The GSH content in the liver was maintained at the original level during perfusion with 1 mM glc-cys for 2h, while it decreased significantly in the absence of glc-cys. After 4h of perfusion without glc-cys, ATP content and bile production decreased significantly besides the decrease in GSH content, but they were maintained at the original levels with glc-cys. When the perfusion was performed with the liver of rats injected with diethyl maleate (DEM), the GSH level, which was decreased to 6.0% of the control by DEM injection, was restored to 22.6% of the original level by perfusion with 2mM glc-cys for 30 min. Data indicate that glccys is a cysteine prodrug with protective action on the liver.  相似文献   
23.
Summary Effect of intraperitoneal administration (5 mmol/kg of body weight) of glucose- cysteine adduct (glc-cys) as a cysteine prodrug in rat tissues was studied. Cysteine levels in liver and kidney increased to 1.08 and 1.98mol per g or ml, respectively, at 2h after the administration. GSH levels did not change substantially. However, when glc-cys was injected to rats treated with diethyl maleate, a GSH-depleting agent, the decreased GSH levels were restored rapidly. The recoveries in liver and kidney were 72% at 1h and 66% at 2h, respectively, after glc-cys administration. Metabolism of glc-cys was assessed by urinary excretion of glc-cys, sulfate and taurine. Average excretion of glc-cys was 2.86mmol/kg/24h after glc-cys administration. Increased excretions of sulfate and taurine were 0.77 and 0.14mmol/kg/24h, respectively. Data show that, although glc-cys excretion was relatively rapid, glc-cys was effectively utilized for GSH synthesis in GSH-depleted tissues.  相似文献   
24.
The ratio of hapten and bovine serum albumin in an antigen conjugate was determined by matrix-assisted laser desorption/ionization mass spectrometry. A hybridoma secreting monoclonal antibodies against solamargine was produced by fusing splenocytes immunized with a solamargine-bovine serum albumin conjugate with HAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. Extensive cross-reaction of anti-solamargine antibodies against solasonine appeared. Aglycone of solamargine, solasodine cross-reacted with anti-solamargine antibodies resulting in a 43.8% cross-reaction. Insignificant cross-reaction appeared with tomatine (2.06%). The full measuring range of the assay extends from 57.5 pmol ml–1 to 11.5 nmol ml–1 of solamargine.  相似文献   
25.
A new phenolic, hydroxyeucomic acid, and dopamine were isolated from Cattleya trianaei and their biological activities examined.  相似文献   
26.
Two new cage-type lupin alkaloids, (?)-tsukushinamine-B and tsukushinamine-C, have been isolated from the fresh epigeal parts of Sophora franchetiana, along with (?)-cytisine, (?)-N-formylcytisine, (?)-rhombifoline, (?)-anagyrine, (?)-baptifoline and (±)-ammodendrine, as well as (?)-tsukushinamine-A. The structures of these novel tsukushinamine-type lupin alkaloids were determined by spectroscopic data and partly by a chemical reaction. Variations of the alkaloid contents in the seeds, seedlings and various parts of S. franchetiana were also examined.  相似文献   
27.

Urban waterlogging stems from coverage with impervious surfaces and increasing rainfall intensity from climate change and variability, meaning that storm water cannot readily infiltrate the ground and excessive surface runoff leads to urban flooding. To reduce related environmental and safety risks, rainfall and groundwater level research was carried out in Kyoto Prefecture with two rain gardens (RG1 and RG2) to investigate flood mitigation functions using a tank model. During the 134 days of monitoring from July 14, 2017, to November 25, 2017, RG1 had seven overflow events with an average runoff control ratio of 63.94%, and RG2 had one event with a ratio of 95.97%. The RG1 tank model (two stages) showed that initial storage for the first and second depths was 6.912?×?10?11 and 0 mm, respectively. The heights of the discharge holes were 20.857 and 0.784 mm for the first stage and 0.659 mm for the second stage, and the discharge hole coefficients were 0.529 and 0.002 for the first stage and 0.004 for the second stage. The results showed that RG1 had penetration hole coefficients of 0.138 (first stage) and 0.254 (second stage), with a water balance error of 0.017 (<?0.02) and a Nash–Sutcliffe efficiency coefficient of 0.922, indicating better reliability and quality than RG2 with the one-stage tank model. Peak flow simulation for mitigation showed that RG1 had a high overflow control ratio (mitigation time 2 h for instant rainfall of 100 mm/h), and can therefore be considered appropriate for other urban areas of Japan.

  相似文献   
28.
Landscape and Ecological Engineering - In the original publication of the article, Figure&nbsp;1 was published incorrectly. The correct figure is given below.  相似文献   
29.
Elucidation of how pancreatic cancer cells give rise to distant metastasis is urgently needed in order to provide not only a better understanding of the underlying molecular mechanisms, but also to identify novel targets for greatly improved molecular diagnosis and therapeutic intervention. We employed combined proteomic technologies including mass spectrometry and isobaric tags for relative and absolute quantification peptide tagging to analyze protein profiles of surgically resected human pancreatic ductal adenocarcinoma tissues. We identified a protein, dihydropyrimidinase-like 3, as highly expressed in human pancreatic ductal adenocarcinoma tissues as well as pancreatic cancer cell lines. Characterization of the roles of dihydropyrimidinase-like 3 in relation to cancer cell adhesion and migration in vitro, and metastasis in vivo was performed using a series of functional analyses, including those employing multiple reaction monitoring proteomic analysis. Furthermore, dihydropyrimidinase-like 3 was found to interact with Ezrin, which has important roles in cell adhesion, motility, and invasion, while that interaction promoted stabilization of an adhesion complex consisting of Ezrin, c-Src, focal adhesion kinase, and Talin1. We also found that exogenous expression of dihydropyrimidinase-like 3 induced activating phosphorylation of Ezrin and c-Src, leading to up-regulation of the signaling pathway. Taken together, the present results indicate successful application of combined proteomic approaches to identify a novel key player, dihydropyrimidinase-like 3, in pancreatic ductal adenocarcinoma tumorigenesis, which may serve as an important biomarker and/or drug target to improve therapeutic strategies.  相似文献   
30.
We have developed chemically modified siRNAs and miRNAs bearing urea/thiourea-bridged aromatic compounds at their 3′-end for RNAi therapy. Chemically modified RNAs possessing urea/thiourea-bridged aromatic compounds instead of naturally occurring dinucleotides at the 3′-overhang region were easily prepared in good yields and were more resistant to nucleolytic hydrolysis than unmodified RNA. siRNAs containing urea or thiourea derivatives showed the desired knockdown effect. Furthermore, modified miR-143 duplexes carrying the urea/thiourea compounds in the 3′-end of each strand were able to inhibit the growth of human bladder cancer T24 cells.  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