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   652112篇
  免费   8246篇
  国内免费   2737篇
化学   337840篇
晶体学   8539篇
力学   31118篇
综合类   15篇
数学   100552篇
物理学   185031篇
  2020年   4178篇
  2019年   4403篇
  2018年   14408篇
  2017年   14088篇
  2016年   14071篇
  2015年   7250篇
  2014年   9323篇
  2013年   27438篇
  2012年   23582篇
  2011年   34471篇
  2010年   21032篇
  2009年   21406篇
  2008年   28666篇
  2007年   30849篇
  2006年   22232篇
  2005年   21407篇
  2004年   19514篇
  2003年   17857篇
  2002年   16602篇
  2001年   17573篇
  2000年   13697篇
  1999年   10837篇
  1998年   8854篇
  1997年   8637篇
  1996年   8609篇
  1995年   7860篇
  1994年   7397篇
  1993年   7246篇
  1992年   7927篇
  1991年   7873篇
  1990年   7308篇
  1989年   7201篇
  1988年   7414篇
  1987年   7052篇
  1986年   6751篇
  1985年   9684篇
  1984年   9802篇
  1983年   8057篇
  1982年   8706篇
  1981年   8403篇
  1980年   8182篇
  1979年   8303篇
  1978年   8530篇
  1977年   8342篇
  1976年   8378篇
  1975年   7958篇
  1974年   7858篇
  1973年   8220篇
  1972年   5019篇
  1971年   3683篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
61.
62.
63.
A generic strategy based on the use of CdSe/ZnS Quantum Dots (QDs) as elemental labels for protein quantification, using immunoassays with elemental mass spectrometry (ICP-MS), detection is presented. In this strategy, streptavidin modified QDs (QDs-SA) are bioconjugated to a biotinylated secondary antibody (b-Ab2). After a multi-technique characterization of the synthesized generic platform (QDs-SA-b-Ab2) it was applied to the sequential quantification of five proteins (transferrin, complement C3, apolipoprotein A1, transthyretin and apolipoprotein A4) at different concentration levels in human serum samples. It is shown how this generic strategy does only require the appropriate unlabeled primary antibody for each protein to be detected. Therefore, it introduces a way out to the need for the cumbersome and specific bioconjugation of the QDs to the corresponding specific recognition antibody for every target analyte (protein). Results obtained were validated with those obtained using UV–vis spectrophotometry and commercial ELISA Kits.  相似文献   
64.
65.
66.
67.
68.
Profiling engineered data with robust mining methods continues attracting attention in knowledge engineering systems. The purpose of this article is to propose a simple technique that deals with non-linear multi-factorial multi-characteristic screening suitable for knowledge discovery studies. The method is designed to proactively seek and quantify significant information content in engineered mini-datasets. This is achieved by deploying replicated fractional-factorial sampling schemes. Compiled multi-response data are converted to a single master-response effectuated by a series of distribution-free transformations and multi-compressed data fusions. The resulting amalgamated master response is deciphered by non-linear multi-factorial stealth stochastics intended for saturated schemes. The stealth properties of our method target processing datasets which might be overwhelmed by a lack of knowledge about the nature of reference distributions at play. Stealth features are triggered to overcome restrictions regarding the data normality conformance, the effect sparsity assumption and the inherent collapse of the ‘unexplainable error’ connotation in saturated arrays. The technique is showcased by profiling four ordinary controlling factors that influence webpage content performance by collecting data from a commercial browser monitoring service on a large scale web host. The examined effects are: (1) the number of Cascading Style Sheets files, (2) the number of JavaScript files, (3) the number of Image files, and (4) the Domain Name System Aliasing. The webpage performance level was screened against three popular characteristics: (1) the time to first visual, (2) the total loading time, and (3) the customer satisfaction. Our robust multi-response data mining technique is elucidated for a ten-replicate run study dictated by an L9(34) orthogonal array scheme where any uncontrolled noise embedded contribution has not been necessarily excluded.  相似文献   
69.
Su  X. F.  Zhang  Y. L.  Maximov  A. L.  Zhang  K.  Xin  Q.  Feng  C. Q.  Bai  X. F.  Wu  W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,...  相似文献   
70.
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