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   3093篇
  免费   246篇
  国内免费   361篇
  2024年   7篇
  2023年   68篇
  2022年   146篇
  2021年   197篇
  2020年   140篇
  2019年   141篇
  2018年   180篇
  2017年   106篇
  2016年   142篇
  2015年   203篇
  2014年   224篇
  2013年   225篇
  2012年   277篇
  2011年   272篇
  2010年   167篇
  2009年   131篇
  2008年   171篇
  2007年   160篇
  2006年   126篇
  2005年   86篇
  2004年   88篇
  2003年   54篇
  2002年   73篇
  2001年   46篇
  2000年   32篇
  1999年   44篇
  1998年   33篇
  1997年   31篇
  1996年   21篇
  1995年   19篇
  1994年   19篇
  1993年   12篇
  1992年   17篇
  1991年   7篇
  1990年   5篇
  1989年   6篇
  1988年   7篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   2篇
  1983年   4篇
  1982年   1篇
  1980年   1篇
排序方式: 共有3700条查询结果,搜索用时 156 毫秒
101.
102.
Sepsis‐associated encephalopathy (SAE) has typically been associated with a poor prognosis. Although sestrin 2 (SESN2) plays a crucial role in metabolic regulation and the stress response, its expression and functional roles in SAE are still unclear. In the present study, SAE was established in mice through caecal ligation and puncture (CLP). The adeno‐associated virus 2 (AAV2)‐mediated SESN2 expression (ie overexpression and knockdown) system was injected into the hippocampi of mice with SAE, and subsequently followed by electron microscopic analysis, the Morris water maze task and pathological examination. Our results demonstrated an increase of SESN2 in the hippocampal neurons of mice with SAE, 2‐16 hours following CLP. AAV2‐mediated ectopic expression of SESN2 attenuated brain damage and loss of learning and memory functions in mice with SAE, and these effects were associated with lower pro‐inflammatory cytokines in the hippocampus. Mechanistically, SESN2 promoted unc‐51‐like kinase 1 (ULK1)‐dependent autophagy in hippocampal neurons through the activation of the AMPK/mTOR signalling pathway. Finally, AMPK inhibition by SBI‐0206965 blocked SESN2‐mediated attenuation of SAE in mice. In conclusion, our findings demonstrated that SESN2 might be a novel pharmacological intervention strategy for SAE treatment through promotion of ULK1‐dependent autophagy in hippocampal neurons.  相似文献   
103.
104.
Tian  Chan  Deng  Tao  Zhu  Xiuhuang  Gong  Chen  Zhao  Yangyu  Wei  Yuan  Li  Rong  Xu  Xiufeng  He  Miaonan  Zhang  Zhiwei  Cheng  Jing  BenWillem  Mol  Qiao  Jie 《中国科学:生命科学英文版》2020,63(3):319-328
In China,the medical guidelines recommend performing noninvasive prenatal testing (NIPT) with caution for pregnant women aged 35 years or older.However,the Mother and Child Health Care Law suggests that all primiparous women whose age is older than 35 years undergo prenatal diagnosis.These two inconsistent suggestions/recommendations have made obstetricians confused about whether to offer NIPT to these older pregnant women.To face this issue and find out the solution we performed a retrospective study of 189,809 NIPT samples collected from 28 provincial-leveled administrative units in China.Of 1,564women with high-risk pregnancies who underwent NIPT,459 (29.3%) did not participate in follow-up.The compound sensitivity and specificity of NIPT for trisomies 21,18 and 13 detection was 99.1%(95%CI,98.0%-99.6%) and 99.9%(95%CI,98.8%-99.9%),respectively.In secundiparous women,NIPT showed high sensitivity and specificity similar to that in primiparous women.The observed risk for trisomies 21 and 18 significantly increased when the maternal age was 39 and older.After the publication of the current NIPT policy,the follow-up rate at our center was 97.9%;however,a large number of women are not in maternal and infant care networks nationwide,and that makes the follow-up rate outside our center relatively low.Our study shows that to balance the prevention of major aneuploidies and the limited resources for prenatal diagnosis,the cut-off age of 35for invasive prenatal diagnosis might be unnecessary.Although the NIPT guidelines are well written,how to practice it effectively,especially in less industrialized areas,is worth discussing.  相似文献   
105.
106.
Pavement design and management practices must be adapted in response to future climate change. While many studies have attempted to identify different methods to adapt pavements to future climate conditions, the potential economic impacts of the adaptations still remain largely unquantified. This study presents the results of a comprehensive life‐cycle cost analysis (LCCA) aimed at quantifying the potential economic impacts of a climate adaptation method, in which an upgraded asphalt binder (Performance Grade PG 76‐22) is used in the construction and maintenance of flexible pavement sections in lieu of the original binder (PG 70‐22) for improved resistance against high temperatures. For each of three major Virginia Department of Transportation (VDOT) districts with different climates, three case studies consisting of typical interstate, primary, and secondary pavement sections were considered. The LCCA accounted for the costs incurred during the mixture's production, maintenance, and use phases of the pavement life cycle by explicitly considering future climate projections, pavement life‐cycle performance, maintenance effects, and work zone user delays. The study concludes that pavements using the upgraded binder not only perform better over time but are also economically advantageous compared to those with the original binder under the conditions of the anticipated future climate conditions (2020–2039).  相似文献   
107.
108.
Guo  K. B.  Qiao  G.  Qiu  Z. L.  Wen  Z.  Yang  H.  Wen  X. P. 《Russian Journal of Plant Physiology》2020,67(1):94-102
Russian Journal of Plant Physiology - Attempts had been made to provide evidences insight into the pattern and physiological mechanism of sweet cherry fruit dropping. However, the fruit abscission...  相似文献   
109.
Intracellular protein degradation is essential for the survival of all organisms, but its role in interspecies interaction is unknown. Here, we show that the ClpXP protease of Pseudomonas aeruginosa suppresses its antimicrobial activity against Staphylococcus aureus, a common pathogen co-isolated with P. aeruginosa from polymicrobial human infections. Using proteomic, biochemical, and molecular genetic approaches, we found that this effect is due to the inhibitory effects of ClpXP on the quorum sensing (QS) of P. aeruginosa, mainly by degrading proteins (e.g., PhnA, PhnB, PqsR, and RhlI) which are critical for the production of QS signal molecules PQS and C4-HSL. We provide evidence that co-culturing with S. aureus induces a decrease in the activity of ClpXP in P. aeruginosa, an effect which was also achieved by the treatment of P. aeruginosa with N-acetylglucosamine (GlcNAc), a widespread chemical present on the surface of diverse cell types from bacteria to humans. These findings extend the range of biological events governed by proteolytic machinery to microbial community structure, thus also suggesting that a chemical-induced alteration of protein homeostasis is a mechanism for interspecies interactions.  相似文献   
110.
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