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   869592篇
  免费   90323篇
  国内免费   603篇
  2018年   8421篇
  2017年   8096篇
  2016年   12634篇
  2015年   19100篇
  2014年   21118篇
  2013年   27933篇
  2012年   30299篇
  2011年   28505篇
  2010年   19875篇
  2009年   18247篇
  2008年   24210篇
  2007年   24738篇
  2006年   23396篇
  2005年   27822篇
  2004年   26607篇
  2003年   24181篇
  2002年   21307篇
  2001年   38936篇
  2000年   38761篇
  1999年   31338篇
  1998年   10936篇
  1997年   11299篇
  1996年   10592篇
  1995年   9923篇
  1994年   9668篇
  1993年   9415篇
  1992年   25813篇
  1991年   25169篇
  1990年   24666篇
  1989年   23994篇
  1988年   22318篇
  1987年   20840篇
  1986年   19309篇
  1985年   19192篇
  1984年   15755篇
  1983年   13070篇
  1982年   9804篇
  1981年   8751篇
  1980年   8185篇
  1979年   14190篇
  1978年   10989篇
  1977年   9864篇
  1976年   8997篇
  1975年   10089篇
  1974年   10848篇
  1973年   10759篇
  1972年   9606篇
  1971年   8819篇
  1970年   7566篇
  1969年   7346篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
711.
Biophysics - HMGB1 is one of the key proteins of the cell. HMGB1 performs its main functions predominantly in the cell nucleus, as an essential component of DNA–protein and multiprotein...  相似文献   
712.
Heart failure is a major clinical problem worldwide. Previous studies have demonstrated an important role for G protein-coupled receptors, including protease-activated receptors (PARs), in the pathology of heart hypertrophy and failure. Activation of PAR-2 on cardiomyocytes has been shown to induce hypertrophic growth in vitro. PAR-2 also contributes to myocardial infarction and heart remodeling after ischemia/reperfusion injury. In this study, we found that PAR-2 induced hypertrophic growth of cultured rat neonatal cardiomyocytes in a MEK1/2 and p38 dependent manner. In addition, PAR-2 activation on mouse cardiomyocytes increased expression of the pro-fibrotic chemokine MCP-1. Furthermore, cardiomyocyte-specific overexpression of PAR-2 in mice induced heart hypertrophy, cardiac fibrosis, inflammation and heart failure. Finally, in a mouse model of myocardial infarction induced by permanent ligation of the left anterior descending coronary artery, PAR-2 deficiency attenuated heart remodeling and improved heart function independently of its contribution to the size of the initial infarct. Taken together, our data indicate that PAR-2 signaling contributes to the pathogenesis of hypertrophy and heart failure.  相似文献   
713.
Dyscalculia, dyslexia, and specific language impairment (SLI) are relatively specific developmental learning disabilities in math, reading, and oral language, respectively, that occur in the context of average intellectual capacity and adequate environmental opportunities. Past research has been dominated by studies focused on single impairments despite the widespread recognition that overlapping and comorbid deficits are common. The present study took an epidemiological approach to study the learning profiles of a large school age sample in language, reading, and math. Both general learning profiles reflecting good or poor performance across measures and specific learning profiles involving either weak language, weak reading, weak math, or weak math and reading were observed. These latter four profiles characterized 70% of children with some evidence of a learning disability. Low scores in phonological short-term memory characterized clusters with a language-based weakness whereas low or variable phonological awareness was associated with the reading (but not language-based) weaknesses. The low math only group did not show these phonological deficits. These findings may suggest different etiologies for language-based deficits in language, reading, and math, reading-related impairments in reading and math, and isolated math disabilities.  相似文献   
714.
Murina  M. A.  Roshchupkin  D. I.  Sergienko  V. I. 《Biophysics》2021,66(4):535-540
Biophysics - A technology has been developed for the preparation of novel chloramine compounds related to adenosine derivatives. The optical absorption characteristics of...  相似文献   
715.
Glushakova  A. M.  Lysak  L. V.  Kachalkin  A. V.  Ivanova  A. E.  Umarova  A. B.  Abramyan  I. A.  Ezhelev  Z. S.  Maksimova  I. A. 《Microbiology》2021,90(2):176-186
Microbiology - In a model experiment, the transformation of microbial complexes of cultivated saprotrophic bacteria and yeasts during freezing-thawing was studied in various natural substrates that...  相似文献   
716.
Microbiology - The surface of the MA8 magnesium alloy, modified by laser treatment, was found to acquire superhydrophilic properties and high bactericidal activity against Escherichia coli K12...  相似文献   
717.
Islam  M.D. Dhin  Price  Adam H.  Hallett  Paul D. 《Plant and Soil》2021,467(1-2):515-530
Plant and Soil - Cracks and biopores in compacted soil such as plough pans could aid deep rooting, mitigating constraints to seasonal upland use of paddy fields for rice production. This research...  相似文献   
718.
Journal of Evolutionary Biochemistry and Physiology - A study of the effect of a seasonal decrease in ambient temperature on the composition of free amino acids and ninhydrin-positive secondary...  相似文献   
719.
Journal of Evolutionary Biochemistry and Physiology - Due to a high occurrence of diabetes mellitus (DM) and its complications, insulin-positive cells detected in different organs are of great...  相似文献   
720.
Journal of Evolutionary Biochemistry and Physiology - Changes in bioelectrical impedance of the myocardium and liver were revealed in male Wistar rats chronically exposed to doxorubicin....  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