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   250584篇
  免费   6697篇
  国内免费   2614篇
电工技术   6818篇
技术理论   5篇
综合类   3115篇
化学工业   36004篇
金属工艺   10680篇
机械仪表   8678篇
建筑科学   7837篇
矿业工程   2502篇
能源动力   6332篇
轻工业   18122篇
水利工程   2563篇
石油天然气   6613篇
武器工业   403篇
无线电   32927篇
一般工业技术   43663篇
冶金工业   48340篇
原子能技术   4207篇
自动化技术   21086篇
  2022年   2342篇
  2021年   3544篇
  2020年   2605篇
  2019年   2723篇
  2018年   3778篇
  2017年   3889篇
  2016年   3769篇
  2015年   3577篇
  2014年   5293篇
  2013年   11035篇
  2012年   7741篇
  2011年   9689篇
  2010年   8110篇
  2009年   8608篇
  2008年   8927篇
  2007年   8906篇
  2006年   8502篇
  2005年   7756篇
  2004年   6769篇
  2003年   6425篇
  2002年   6155篇
  2001年   6294篇
  2000年   6098篇
  1999年   6889篇
  1998年   16761篇
  1997年   11306篇
  1996年   8926篇
  1995年   6658篇
  1994年   5708篇
  1993年   5478篇
  1992年   3740篇
  1991年   3551篇
  1990年   3451篇
  1989年   3229篇
  1988年   2953篇
  1987年   2344篇
  1986年   2396篇
  1985年   2664篇
  1984年   2365篇
  1983年   2099篇
  1982年   1933篇
  1981年   2071篇
  1980年   1807篇
  1979年   1665篇
  1978年   1663篇
  1977年   2029篇
  1976年   2715篇
  1975年   1426篇
  1974年   1370篇
  1973年   1318篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Wireless Personal Communications - In the fusion experiment, sensitive radio frequency signal diagnostic instruments need to be protected against high power stray radiation coming from the Electron...  相似文献   
42.
Sustainable and efficient food supply chain has become an essential component of one’s life. The model proposed in this paper is deeply linked to people's quality of life as a result of which there is a large incentive to fulfil customer demands through it. This proposed model can enhance food quality by making the best possible food quality accessible to customers, construct a sustainable logistics system considering its environmental impact and ensure the customer demand to be fulfilled as fast as possible. In this paper, an extended model is examined that builds a unified planning problem for efficient food logistics operations where four important objectives are viewed: minimising the total expense of the system, maximising the average food quality along with the minimisation of the amount of CO2 emissions in transportation along with production and total weighted delivery lead time minimisation. A four objective mixed integer linear programming model for intelligent food logistics system is developed in the paper. The optimisation of the formulated mathematical model is proposed using a modified multi-objective particle swarm optimisation algorithm with multiple social structures: MO-GLNPSO (Multi-Objective Global Local Near-Neighbour Particle Swarm Optimisation). Computational results of a case study on a given dataset as well as on multiple small, medium and large-scale datasets followed by sensitivity analysis show the potency and effectiveness of the introduced method. Lastly, there has been a scope for future study displayed which would lead to the further progress of these types of models.  相似文献   
43.
Yuan  Zhongchen  Yan  Li  Ma  Zongmin 《Requirements Engineering》2020,25(2):213-229
Requirements Engineering - In software reuse, the reuse of UML class diagram produced in design phase has received more attention due to the important influence on the following developing process....  相似文献   
44.
45.
46.
47.
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   
48.
49.
50.
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