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   1252404篇
  免费   100798篇
  国内免费   1356篇
  2021年   18098篇
  2020年   12795篇
  2019年   16422篇
  2018年   17995篇
  2017年   16738篇
  2016年   28499篇
  2015年   42888篇
  2014年   50933篇
  2013年   77598篇
  2012年   34467篇
  2011年   22318篇
  2010年   43575篇
  2009年   45095篇
  2008年   21320篇
  2007年   19028篇
  2006年   24496篇
  2005年   25695篇
  2004年   24783篇
  2003年   22519篇
  2002年   20625篇
  2001年   26077篇
  2000年   23292篇
  1999年   25417篇
  1998年   24619篇
  1997年   24242篇
  1996年   23904篇
  1995年   22032篇
  1994年   21867篇
  1993年   20901篇
  1992年   22530篇
  1991年   21231篇
  1990年   19846篇
  1989年   21021篇
  1988年   19275篇
  1987年   18236篇
  1986年   17324篇
  1985年   19500篇
  1984年   20128篇
  1983年   17842篇
  1982年   19123篇
  1981年   18522篇
  1980年   17344篇
  1979年   15997篇
  1978年   15888篇
  1977年   15327篇
  1976年   14590篇
  1975年   13961篇
  1974年   14358篇
  1973年   14765篇
  1972年   12443篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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   
992.
Masherov  E. L. 《Biophysics》2021,66(4):665-670

A model of activity generation in the epileptic focus was proposed based on the ideas that synchronization occurs between the oscillations that arise to regulate the resting potential level and that neuronal discharges are synchronized with slow oscillations. Four phases were identified in seizure development: an increase in slow-wave activity, high-frequency spike activity, synchronization in the presence of sharp peaks, and extinction of the seizure. The model was compared with an intraoperative electrocorticography record.

  相似文献   
993.
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   
994.
Vorobieva  V. V.  Shabanov  P. D. 《Biophysics》2021,66(4):610-613
Biophysics - A change in the content of energy substrates in myocardial mitochondria depending upon the vibration frequency and the duration of the total vertical vibration exposure was studied...  相似文献   
995.
Naumova  E. V.  Vladimirov  Yu. A.  Beloussov  L. V.  Tuchin  V. V.  Volodyaev  I. V. 《Biophysics》2021,66(5):764-778
Biophysics - This review is devoted to the methods for studying the ultraweak luminescence of biological objects; in addition to modern methods aimed at studies in the visible, near-infrared, and...  相似文献   
996.
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   
997.
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   
998.
Ding  Jingyi  Eldridge  David J. 《Plant and Soil》2021,459(1-2):173-183
Plant and Soil - Perennial plants play important roles in maintaining ecosystem functions by forming fertile islands beneath their canopies. Little is known about how the fertile island effect...  相似文献   
999.
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   
1000.
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   
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