首页 | 官方网站   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   732389篇
  免费   10591篇
  国内免费   2342篇
工业技术   745322篇
  2021年   5935篇
  2020年   4413篇
  2019年   5688篇
  2018年   9369篇
  2017年   9444篇
  2016年   10166篇
  2015年   7059篇
  2014年   11492篇
  2013年   35546篇
  2012年   19154篇
  2011年   26612篇
  2010年   20797篇
  2009年   23666篇
  2008年   24646篇
  2007年   24658篇
  2006年   22163篇
  2005年   20091篇
  2004年   19400篇
  2003年   19045篇
  2002年   18288篇
  2001年   18161篇
  2000年   17008篇
  1999年   17946篇
  1998年   43331篇
  1997年   30887篇
  1996年   24022篇
  1995年   18335篇
  1994年   16325篇
  1993年   16039篇
  1992年   11788篇
  1991年   11177篇
  1990年   10872篇
  1989年   10332篇
  1988年   9937篇
  1987年   8554篇
  1986年   8427篇
  1985年   9912篇
  1984年   9216篇
  1983年   8135篇
  1982年   7542篇
  1981年   7594篇
  1980年   7090篇
  1979年   6889篇
  1978年   6555篇
  1977年   7731篇
  1976年   10310篇
  1975年   5573篇
  1974年   5286篇
  1973年   5242篇
  1972年   4322篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
105.
106.
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies.  相似文献   
107.
Interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane in xylene and under mechanochemical activation conditions has been investigated. The interaction in solution proceeds with splitting of the siloxane bond and formation of polymolybdenum(VI) phenylsiloxane with different silicon/metal ratios. The fractions with the silicon/metal ratio < 2 are characterized with high degree of crystallinity and low solubility, whereas those with the ratio > 2 are amorphous. The interaction of the above reagents under mechanical activation conditions proceeds with the formation of soluble polymers similar to those obtained in a solution with the silicon/molybdenum ratio equal to 2.6. The crystal chemistry parameters of the fraction obtained in solution with the ratio Si/Mo equals to 1:2 have been calculated on the basis of the X-ray diffraction analysis data using the Debye–Shearer equation. It has been demonstrated that the chain cross section found using the Miller–Boyer method coincides with that calculated geometrically on the basis of literature data on bond lengths and angles. It is shown that the interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane takes place in solution more deeply than under the conditions of mechanochemical activation and is accompanied by the process of separation siloxanes connection. This leads to the formation of a fraction with smaller ratio of substances than the initial ratio.  相似文献   
108.
109.
110.
Combustion, Explosion, and Shock Waves - This paper presents an analytical review of modern quasihomogeneous and discrete models of gasless combustion. Particular attention is given to experiments...  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-23

京公网安备 11010802026262号