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   438326篇
  免费   9415篇
  国内免费   2733篇
电工技术   9465篇
综合类   2314篇
化学工业   65367篇
金属工艺   15789篇
机械仪表   13725篇
建筑科学   13850篇
矿业工程   1808篇
能源动力   11994篇
轻工业   45577篇
水利工程   3878篇
石油天然气   3362篇
武器工业   272篇
无线电   58663篇
一般工业技术   79892篇
冶金工业   76083篇
原子能技术   5924篇
自动化技术   42511篇
  2021年   4224篇
  2020年   3029篇
  2019年   3452篇
  2018年   4876篇
  2017年   5008篇
  2016年   5149篇
  2015年   4900篇
  2014年   7406篇
  2013年   21208篇
  2012年   12231篇
  2011年   16665篇
  2010年   12981篇
  2009年   14517篇
  2008年   15480篇
  2007年   15698篇
  2006年   14134篇
  2005年   13100篇
  2004年   12369篇
  2003年   11853篇
  2002年   11464篇
  2001年   11571篇
  2000年   10704篇
  1999年   11232篇
  1998年   24361篇
  1997年   17879篇
  1996年   14169篇
  1995年   11193篇
  1994年   9959篇
  1993年   9462篇
  1992年   7212篇
  1991年   6863篇
  1990年   6454篇
  1989年   6155篇
  1988年   5888篇
  1987年   4913篇
  1986年   4861篇
  1985年   5984篇
  1984年   5605篇
  1983年   4837篇
  1982年   4503篇
  1981年   4404篇
  1980年   4136篇
  1979年   4029篇
  1978年   3725篇
  1977年   4502篇
  1976年   6057篇
  1975年   3085篇
  1974年   2974篇
  1973年   2851篇
  1972年   2292篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
51.
52.
Upper Barremian – Lower Aptian inner platform “Urgonian” limestones in the Mont de Vaucluse region, SE France, consist of alternating metre-scale microporous and tight intervals. This paper focuses on the influence of structural deformation on the reservoir properties of the Urgonian limestone succession in a study area near the town of Rustrel. Petrographic, petrophysical and structural data were recovered from five fully-cored boreholes, from the walls of a 100 m long underground tunnel, and from a 50 m long transect at a nearby outcrop. The data allowed reservoir property variations in the Urgonian limestones to be studied from core to reservoir scale. Eleven Reservoir Rock Types (RRTs) were identified based on petrographic features (texture, grain size), reservoir properties (porosity, permeability), and the frequency of structural discontinuities such as fractures, faults and stylolites. Tight and microporous reservoir rock types were distinguished. Tight reservoir rock types were characterised by early cementation of intergranular pore spaces and by the presence of frequent structural discontinuities. By contrast microporous reservoir rock types contained preserved intragranular microporosity and matrix permeability, but had very few structural discontinuities. Observed vertical alternations of microporous and tight rock types are interpreted to have been controlled by the early diagenesis of the Urgonian carbonates. Deformation associated with regional-scale tectonic phases, including Albian – Cenomanian “Durancian” uplift (∼105 to 96 Ma) and Pyrenean compression (∼55 to 25 Ma), resulted in the modification of the initial petrophysical properties of the Urgonian limestones. An early diagenetic imprint conditioned both the intensity of structural deformations and the associated circulations of diagenetic and meteoric fluids. Evolution of the Reservoir Rock Types is therefore linked both to the depositional conditions and to subsequent phases of structural deformation.  相似文献   
53.
54.
55.
56.
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   
57.
58.
59.
60.
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