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   14990篇
  免费   1150篇
  国内免费   1106篇
  17246篇
  2024年   32篇
  2023年   175篇
  2022年   454篇
  2021年   821篇
  2020年   487篇
  2019年   596篇
  2018年   625篇
  2017年   522篇
  2016年   620篇
  2015年   892篇
  2014年   1069篇
  2013年   1200篇
  2012年   1397篇
  2011年   1251篇
  2010年   774篇
  2009年   683篇
  2008年   751篇
  2007年   624篇
  2006年   605篇
  2005年   486篇
  2004年   429篇
  2003年   330篇
  2002年   344篇
  2001年   312篇
  2000年   254篇
  1999年   249篇
  1998年   165篇
  1997年   130篇
  1996年   133篇
  1995年   125篇
  1994年   138篇
  1993年   92篇
  1992年   96篇
  1991年   70篇
  1990年   66篇
  1989年   58篇
  1988年   56篇
  1987年   31篇
  1986年   33篇
  1985年   19篇
  1984年   23篇
  1983年   12篇
  1982年   8篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1976年   1篇
  1975年   1篇
  1933年   1篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
821.
Thioredoxin-interacting protein (TXNIP) is induced by high glucose (HG), whereupon it acts to inhibit thioredoxin, thereby promoting oxidative stress. We have found that TXNIP knockdown in human renal tubular cells helped prevent the epithelial-to-mesenchymal transition (EMT). Here, we studied the potential effect of TXNIP on podocyte phenotypic alterations in diabetic nephropathy (DN) in vivo and in vitro. In conditionally immortalized mouse podocytes under HG conditions, knocking down TXNIP disrupted EMT, reactive oxygen species (ROS) production, and mammalian target of rapamycin (mTOR) pathway activation. Further, Raptor short hairpin RNA (shRNA), Rictor shRNA, and mTOR specific inhibitor KU-0063794 were used to assess if the mTOR signal pathway is involved in HG-induced EMT in podocytes. We found that Raptor shRNA, Rictor shRNA, and KU-0063794 could all restrain HG-induced EMT and ROS production in podocytes. In addition, antioxidant Tempol or N-acetylcysteine presented a prohibitive effect on HG-induced EMT in podocytes. Streptozotocin was utilized to render equally diabetic in wild-type (WT) control and TXNIP −/− (TKO) mice. Diabetes did not increase levels of 24-hr urinary protein, serum creatinine, blood urea nitrogen, and triglyceride in TXNIP −/− mice. Podocyte phenotypic alterations and podocyte loss were detected in WT but not in TKO diabetic mice. Oxidative stress was also suppressed in diabetic TKO mice relative to WT controls. Also, TXNIP deficiency suppresses the activation of mTOR in glomeruli of streptozotocin-induced diabetic mice. Moreover, TXNIP expression, mTOR activation, Nox1, and Nox4 could be detected in renal biopsy tissues of patients with DN. This suggests that decreased TXNIP could ameliorate phenotypic alterations of podocytes via inhibition of mTOR in DN, highlighting TXNIP as a promising therapeutic target.  相似文献   
822.
823.
Zhang  Xiaonan  Lu  Yufang  Yang  Ting  Kronzucker  Herbert J.  Shi  Weiming 《Plant and Soil》2019,441(1-2):253-259
Plant and Soil - Depending on the availability and stoichiometry of nutrients in soil, microbes and plants can compete for the same resources. In this study we aimed to test how microbial nutrient...  相似文献   
824.
825.
Sepals play important roles in protecting inner floral organs from various stresses and in guaranteeing timely flower opening. However, the exact role of sepals in coordinating interior and exterior signals remains elusive. In this study, we functionally characterized a heat shock protein gene, Arabidopsis HSP70‐16, in flower opening and mild heat stress response, using combined genetics with anatomic, physiological, chemical, and molecular analyses. We showed that HSP70‐16 is required for flower opening and mild heat response. Mutation of HSP70‐16 led to a significant reduction in seed setting rate under 22°C, which was more severe at 27°C. Mutation of HSP70‐16 also caused postgenital fusion at overlapping tips of two lateral sepals, leading to failed flower opening, abnormal floral organ formation, and impaired fertilization and seed setting. Chemical and anatomic analyses confirmed specific chemical and morphological changes of cuticle property in mutant lateral sepals, and qRT‐PCR data indicated that expression levels of different sets of cuticle regulatory and biosynthetic genes were altered in mutants grown at both 22°C and 27°C temperatures. This study provides a link between thermal and developmental perception signals and expands the understanding of the roles of sepal in plant development and heat response.  相似文献   
826.
827.
Liu  Shuai  Li  Su  Fan  Xiao-Yang  Yuan  Guo-Di  Hu  Tao  Shi  Xian-Meng  Huang  Jun-Biao  Pu  Xiao-Yan  Wu  Chuan-Sheng 《Photosynthesis research》2019,141(2):245-257
Photosynthesis Research - Chlorophyll content in lichens is routinely used as an accurate indicator of lichen vigor, interspecific differences, and the effect of site-related environmental...  相似文献   
828.
The treatment of cancer has made great progress. However, drug resistance remains problematic. Multiple physiologic processes of tumor development can be dominated by central and sympathetic nervous systems. The interactions between the nervous system, immune system, and tumor occur consistently and dynamically. Recent evidence suggests that nerves and neural signals are intimately involved in the development of resistance to cancer therapies. In this review, we will provide an overview of the recent progress in this rapidly growing area and discuss the potential new strategies for targeting the neural signaling pathway to improve the effectiveness of chemotherapies, targeted therapies, and immunotherapies.  相似文献   
829.
Long  Huiping  Zhong  Gang  Wang  Chengzhi  Zhang  Jian  Zhang  Yueling  Luo  Jinglian  Shi  Shengliang 《Neurochemical research》2019,44(8):1830-1839
Neurochemical Research - The pathogenesis of late-onset Alzheimer's disease (LOAD) mainly involves abnormal accumulation of extracellular β-amyloid (Aβ) and the consequent neurotoxic...  相似文献   
830.
Pseudomonas amygdali pv. lachrymans is currently of important plant pathogenic bacteria that causes cucumber angular leaf spot worldwide. The pathogen has been studied for its roles in pathogenicity and plant inheritance resistance. To further delineate traits critical to virulence, invasion and survival in the phyllosphere, we reported the first complete genome of P. amygdali pv. lachrymans NM002. Analysis of the whole genome in comparison with three closely-related representative pathovars of P. syringae identified the conservation of virulence genes, including flagella and chemotaxis, quorum-sensing systems, two-component systems, and lipopolysaccharide and antiphagocytosis. It also revealed differences of invasion determinants, such as type III effectors, phytotoxin (coronatine, syringomycin and phaseolotoxin) and cell wall-degrading enzyme, which may contribute to infectivity. The aim of this study was to derive genomic information that would reveal the probable molecular mechanisms underlying the virulence, infectivity and provide a better understanding of the pathogenesis of the P. syringae pathovars.  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