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   1845篇
  免费   253篇
  国内免费   4篇
  2021年   24篇
  2020年   11篇
  2019年   15篇
  2018年   16篇
  2017年   16篇
  2016年   44篇
  2015年   49篇
  2014年   80篇
  2013年   87篇
  2012年   94篇
  2011年   109篇
  2010年   80篇
  2009年   65篇
  2008年   92篇
  2007年   93篇
  2006年   108篇
  2005年   78篇
  2004年   95篇
  2003年   65篇
  2002年   63篇
  2001年   48篇
  2000年   53篇
  1999年   32篇
  1998年   31篇
  1997年   16篇
  1996年   24篇
  1995年   18篇
  1994年   15篇
  1993年   9篇
  1992年   31篇
  1991年   24篇
  1990年   33篇
  1989年   31篇
  1988年   28篇
  1987年   40篇
  1986年   36篇
  1985年   19篇
  1984年   25篇
  1983年   16篇
  1982年   19篇
  1981年   27篇
  1980年   20篇
  1979年   25篇
  1978年   20篇
  1977年   11篇
  1976年   16篇
  1975年   16篇
  1974年   12篇
  1973年   10篇
  1972年   16篇
排序方式: 共有2102条查询结果,搜索用时 15 毫秒
91.
Natural or early weaning of rat litters caused an increased activity of maternal luteal 20alpha-hydroxy steroid dehydrogenase and a decreased release of delta4-3-oxo steroids in vitro. 2. Compound CB-154 (2-bromo-alpha-ergocryptine) caused an increase of 20alpha-hydroxy steroid dehydrogenase activity in mid-lactation but not in early lactation. 3. Prolaction did not prevent these increases in enzyme activity.  相似文献   
92.
93.
Powdery mildew is a common and widespread plant disease of considerable agronomic relevance. It is caused by obligate biotrophic fungal pathogens which, in most cases, epiphytically colonize aboveground plant tissues. The disease has been typically studied as a binary interaction of the fungal pathogen with its plant hosts, neglecting, for the most part, the mutual interplay with the wealth of other microorganisms residing in the phyllo- and/or rhizosphere and roots. However, the establishment of powdery mildew disease can be impacted by the presence/absence of host-associated microbiota (epi- and endophytes) and, conversely, plant colonization by powdery mildew fungi might disturb indigenous microbial community structures. In addition, other (foliar) phytopathogens could interact with powdery mildews, and mycoparasites may affect the outcome of plant–powdery mildew interactions. In this review, we discuss the current knowledge regarding the intricate and multifaceted interplay of powdery mildew fungi, host plants and other microorganisms, and outline current gaps in our knowledge, thereby setting the basis for potential future research directions.  相似文献   
94.
95.
96.
Metabolomics - Metabolomics applications to the aquaculture research are increasing steadily. The use of standardized proton nuclear magnetic resonance (1H NMR) spectroscopy can provide the...  相似文献   
97.
98.
In the present study, we investigated the therapeutic potential of a selective S1P1 receptor modulator, ponesimod, to protect and reverse autoimmune diabetes in non-obese diabetic (NOD) mice. Ponesimod was administered orally to NOD mice starting at 6, 10, 13 and 16 weeks of age up to 35 weeks of age or to NOD mice showing recent onset diabetes. Peripheral blood and spleen B and T cell counts were significantly reduced after ponesimod administration. In pancreatic lymph nodes, B lymphocytes were increased and expressed a transitional 1-like phenotype. Chronic oral ponesimod treatment efficiently prevented autoimmune diabetes in 6, 10 and 16 week-old pre-diabetic NOD mice. Treatment withdrawal led to synchronized disease relapse. Ponesimod did not inhibit the differentiation of autoreactive T cells as assessed by adoptive transfer of lymphocytes from treated disease-free NOD mice. In addition, it did not affect the migration, proliferation and activation of transgenic BDC2.5 cells into the target tissue. However, ponesimod inhibited spreading of the T cell responses to islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP). Treatment of diabetic NOD mice with ponesimod induced disease remission. However, here again, upon treatment cessation, the disease rapidly recurred. This recurrence was effectively prevented by combination treatment with a CD3 antibody leading to the restoration of self-tolerance. In conclusion, treatment with a selective S1P1 modulator in combination with CD3 antibody represents a promising therapeutic approach for the treatment of autoimmune diabetes.  相似文献   
99.
100.
Enhancing chondrogenic and osteogenic differentiation is of paramount importance in providing effective regenerative therapies and improving the rate of fracture healing. This study investigated the potential of non-thermal atmospheric dielectric barrier discharge plasma (NT-plasma) to enhance chondrocyte and osteoblast proliferation and differentiation. Although the exact mechanism by which NT-plasma interacts with cells is undefined, it is known that during treatment the atmosphere is ionized generating extracellular reactive oxygen and nitrogen species (ROS and RNS) and an electric field. Appropriate NT-plasma conditions were determined using lactate-dehydrogenase release, flow cytometric live/dead assay, flow cytometric cell cycle analysis, and Western blots to evaluate DNA damage and mitochondrial integrity. We observed that specific NT-plasma conditions were required to prevent cell death, and that loss of pre-osteoblastic cell viability was dependent on intracellular ROS and RNS production. To further investigate the involvement of intracellular ROS, fluorescent intracellular dyes Mitosox (superoxide) and dihydrorhodamine (peroxide) were used to assess onset and duration after NT-plasma treatment. Both intracellular superoxide and peroxide were found to increase immediately post NT-plasma treatment. These increases were sustained for one hour but returned to control levels by 24 hr. Using the same treatment conditions, osteogenic differentiation by NT-plasma was assessed and compared to peroxide or osteogenic media containing β-glycerolphosphate. Although both NT-plasma and peroxide induced differentiation-specific gene expression, neither was as effective as the osteogenic media. However, treatment of cells with NT-plasma after 24 hr in osteogenic or chondrogenic media significantly enhanced differentiation as compared to differentiation media alone. The results of this study show that NT-plasma can selectively initiate and amplify ROS signaling to enhance differentiation, and suggest this technology could be used to enhance bone fusion and improve healing after skeletal injury.  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