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   19109篇
  免费   749篇
  国内免费   46篇
电工技术   239篇
综合类   24篇
化学工业   3747篇
金属工艺   472篇
机械仪表   401篇
建筑科学   958篇
矿业工程   108篇
能源动力   614篇
轻工业   1653篇
水利工程   173篇
石油天然气   67篇
无线电   1508篇
一般工业技术   3400篇
冶金工业   3456篇
原子能技术   118篇
自动化技术   2966篇
  2023年   118篇
  2022年   167篇
  2021年   329篇
  2020年   237篇
  2019年   274篇
  2018年   371篇
  2017年   386篇
  2016年   421篇
  2015年   341篇
  2014年   521篇
  2013年   1232篇
  2012年   833篇
  2011年   1182篇
  2010年   807篇
  2009年   838篇
  2008年   939篇
  2007年   877篇
  2006年   767篇
  2005年   754篇
  2004年   605篇
  2003年   548篇
  2002年   531篇
  2001年   334篇
  2000年   304篇
  1999年   331篇
  1998年   369篇
  1997年   303篇
  1996年   333篇
  1995年   309篇
  1994年   293篇
  1993年   264篇
  1992年   261篇
  1991年   167篇
  1990年   231篇
  1989年   211篇
  1988年   170篇
  1987年   168篇
  1986年   159篇
  1985年   194篇
  1984年   200篇
  1983年   165篇
  1982年   173篇
  1981年   168篇
  1980年   147篇
  1979年   170篇
  1978年   124篇
  1977年   123篇
  1976年   162篇
  1975年   126篇
  1973年   108篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable.  相似文献   
3.
4.
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   
5.
6.
Journal of Mechanical Science and Technology - This study delivers equations useful for low-height pleated fibrous filter design: two pressure drop equations and one set of optimum design equations...  相似文献   
7.
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   
8.
To quantify the evacuation process, evacuation practitioners use engineering egress data describing the occupant movement characteristics. These data are typically based to young and fit populations. However, the movement abilities of occupants who might be involved in evacuations are becoming more variable—with the building populations of today typically including increasing numbers of individuals: with impairments or who are otherwise elderly or generally less mobile. Thus, there will be an increasing proportion of building occupants with reduced ability to egress. For safe evacuation, there is therefore a need to provide valid engineering egress data considering pedestrians with disabilities. Gwynne and Boyce recently compiled a series of data sets related to the evacuation process to support practitioner activities in the chapter Engineering Data in the SFPE Handbook of Fire Protection Engineering. This paper supplements these data sets by providing information on and presenting data obtained from additional research related to the premovement and horizontal movement of participants with physical‐, cognitive‐, or age‐related disabilities. The aim is to provide an overview of currently available data sets related to, and key factors affecting the egress performance of, mixed ability populations which could be used to guide fire safety engineering decisions in the context of building design.  相似文献   
9.
Armand  Louis 《AI & Society》2020,35(1):257-262
AI & SOCIETY - This paper is addressed to recent theoretical discussions of the Anthropocene, in particular Bernard Stiegler’s Neganthropocene (Open Universities Press, 2018), which...  相似文献   
10.
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