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   26860篇
  免费   855篇
  国内免费   57篇
电工技术   356篇
综合类   31篇
化学工业   5647篇
金属工艺   444篇
机械仪表   539篇
建筑科学   1671篇
矿业工程   140篇
能源动力   673篇
轻工业   2148篇
水利工程   213篇
石油天然气   205篇
武器工业   2篇
无线电   1642篇
一般工业技术   4291篇
冶金工业   5649篇
原子能技术   232篇
自动化技术   3889篇
  2022年   255篇
  2021年   356篇
  2020年   272篇
  2019年   341篇
  2018年   432篇
  2017年   369篇
  2016年   507篇
  2015年   422篇
  2014年   627篇
  2013年   1661篇
  2012年   1055篇
  2011年   1404篇
  2010年   1083篇
  2009年   1045篇
  2008年   1284篇
  2007年   1280篇
  2006年   1041篇
  2005年   1026篇
  2004年   842篇
  2003年   779篇
  2002年   734篇
  2001年   501篇
  2000年   457篇
  1999年   459篇
  1998年   571篇
  1997年   492篇
  1996年   459篇
  1995年   469篇
  1994年   383篇
  1993年   438篇
  1992年   401篇
  1991年   238篇
  1990年   329篇
  1989年   361篇
  1988年   294篇
  1987年   280篇
  1986年   262篇
  1985年   343篇
  1984年   350篇
  1983年   285篇
  1982年   282篇
  1981年   291篇
  1980年   238篇
  1979年   271篇
  1978年   241篇
  1977年   243篇
  1976年   202篇
  1975年   235篇
  1974年   195篇
  1973年   180篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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   
12.
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified.  相似文献   
13.
14.
15.
<正>悉尼理工大学工程和计算机系系馆位于市区的显赫地段,旨在重新给大学城市校区注入活力,成为悉尼商务中心南端的门户。建筑本体如同一件雕塑作品,迥然和周围的传统建筑风格相异。建筑地上14层,地下4层,设有先进的演讲厅、学术办公室、会议室、学习和研究实验室、营业咖啡厅、娱乐区、停车场,并在隔壁建筑旁设计自行车停靠处。  相似文献   
16.
In eukaryotes, microRNAs (miRNAs) have roles in development, homeostasis, disease and the immune response. Recent work has shown that plant and mammalian miRNAs also mediate cross-kingdom and cross-domain communications. However, these studies remain controversial and are lacking critical mechanistic explanations. Bacteria do not produce miRNAs themselves, and therefore it is unclear how these eukaryotic RNA molecules could function in the bacterial recipient. In this review, we compare and contrast the biogenesis and functions of regulatory RNAs in eukaryotes and bacteria. As a result, we discovered several conserved features and homologous components in these distinct pathways. These findings enabled us to propose novel mechanisms to explain how eukaryotic miRNAs could function in bacteria. Further understanding in this area is necessary to validate the findings of existing studies and could facilitate the use of miRNAs as novel tools for the directed remodelling of the human microbiota.  相似文献   
17.
Few jurisdictions have translated internationally agreed social impact assessment (SIA) principles into statutory provisions. Governments and regulatory bodies tend to provide developers with high-level frameworks, or require that social impacts be ‘considered’, without specifying how this is to be done. In Australia, this lack of clarity leaves all parties uncertain about requirements for SIA. The New South Wales (NSW) Government’s 2017 release of the SIA guideline for State-significant mining, petroleum and extractive industry development represents an attempt to clarify requirements and provide guidance. In this paper, we describe the process of bringing this guideline to fruition from the perspective of being directly involved in its development, and highlight the challenges involved in integrating leading-practice principles into the state’s pre-existing policy framework. While the guideline represents a significant advance in policy-based SIA guidance, some aspects leave room for improvement. The real test of the guideline’s impact will lie in its influence on SIA practice in NSW, and ultimately in social outcomes for communities affected by resources projects.  相似文献   
18.
Forschung im Ingenieurwesen - Lkw-Überholmanöver auf Autobahnen können Konfliktsituationen provozieren. Das lange Blockieren der Überholspur und plötzliche Ausscheren kann...  相似文献   
19.
20.
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