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   9759篇
  免费   356篇
  国内免费   108篇
电工技术   232篇
综合类   193篇
化学工业   1922篇
金属工艺   354篇
机械仪表   358篇
建筑科学   348篇
矿业工程   103篇
能源动力   338篇
轻工业   599篇
水利工程   107篇
石油天然气   156篇
武器工业   16篇
无线电   1100篇
一般工业技术   2204篇
冶金工业   1147篇
原子能技术   113篇
自动化技术   933篇
  2023年   92篇
  2022年   176篇
  2021年   228篇
  2020年   188篇
  2019年   148篇
  2018年   253篇
  2017年   200篇
  2016年   217篇
  2015年   201篇
  2014年   269篇
  2013年   577篇
  2012年   387篇
  2011年   457篇
  2010年   389篇
  2009年   367篇
  2008年   365篇
  2007年   336篇
  2006年   311篇
  2005年   260篇
  2004年   235篇
  2003年   221篇
  2002年   206篇
  2001年   172篇
  2000年   221篇
  1999年   230篇
  1998年   307篇
  1997年   262篇
  1996年   235篇
  1995年   195篇
  1994年   187篇
  1993年   172篇
  1992年   150篇
  1991年   151篇
  1990年   104篇
  1989年   108篇
  1988年   117篇
  1987年   115篇
  1986年   92篇
  1985年   133篇
  1984年   125篇
  1983年   136篇
  1982年   96篇
  1981年   99篇
  1980年   87篇
  1979年   90篇
  1978年   79篇
  1977年   66篇
  1976年   72篇
  1975年   59篇
  1974年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Ganapati  Reddi  Samoju  Visweswara Rao  Jammu  Bhaskara Rao 《SILICON》2021,13(9):2869-2880
Silicon - This paper presents, analytical modeling of surface potential,threshold voltage and DIBL for a Dual-Metal Double-Gate Gate-All-Around (DM-DG-GAA) MOSFET considering the parabolic...  相似文献   
3.
4.
5.
In fractured reservoirs, an effective matrix-fracture mass transfer is required for oil recovery. Surfactants have long been considered for oil recovery enhancement, mainly in terms of their ability to reduce oil–water interfacial tension. These surfactants are effective when the fractured formations are water-wet, where capillary imbibition of surfactants from the fracture into the matrix contributes to oil recovery. However, another beneficial aspect of surfactants, namely their ability to alter wettability, remains to be explored and exploited. Surfactants capable of altering wettability can be especially beneficial in oil-wet fractured formations, where the surfactant in the fracture diffuses into the matrix and alters the wettability, enabling imbibition of even more surfactant into the matrix. This sequential process of initial diffusion followed by imbibition continues well into the matrix yielding significant enhancements in oil recovery.In order to test this hypothesis of sequential diffusion–imbibition phenomenon, Dual-Drop Dual-Crystal (DDDC) contact angle experiments have been conducted using fractured Yates dolomite reservoir fluids, two types of surfactants (nonionic and anionic) and dolomite rock substrates. A new experimental procedure was developed in which crude oil equilibrated with reservoir brine has been exposed to surfactant to simulate the matrix-fracture interactions in fractured reservoirs. This procedure enables the measurements of dynamic contact angles and oil–water interfacial tensions, in addition to providing the visual observations of the dynamic behavior of crude oil trapped in the rock matrix as it encounters the diffusing surfactant from the fractures. Both the measurements and visual observations indicate wettability alterations of the matrix surface from oil-wet to less oil-wet or intermediate wet by the surfactants. Thus this study is of practical importance to oil-wet fractured formations where surfactant-induced wettability alterations can result in significant oil recovery enhancements. In addition, this study has also identified the need to include contact angle term in the dimensionless Bond number formulations for better quantitative interpretation of rock–fluids interactions.  相似文献   
6.
陶瓷企业实施MRPⅡ现状及问题分析   总被引:1,自引:0,他引:1  
分析了我国陶瓷企业实施制造资源计划的现状,并提出了成功实施的方略,最后通过实例进行了分析。  相似文献   
7.
燕皮传统加工工艺中碱液对肉糜特性的影响   总被引:1,自引:1,他引:0  
燕皮是以猪肉和甘薯粉为原料,手工制成的薄如纸且经煮不烂的传统食品。在传统制作燕皮过程中添加山榉灰配制的碱液是影响肉糜品质的关键步骤。通过测定制作燕皮过程中各工序样品的氮溶解指数、持水性、乳化稳定性、pH值和粘度,利用SDS-PAGE分析样品中的蛋白质组分、利用光学显微镜观察它们的结构变化,证实植物碱液能够提高样品的氮溶解指数、持水性和乳化稳定性并且延迟了肉糜硬化。同时实验证明碳酸碱(Na2CO3或K2CO3)可替代传统工艺中的植物碱,为后续标准化、工业化生产提供可行条件。  相似文献   
8.
The introduction of high spatial and spectral resolution sensors on-board remote-sensing spacecraft has increased, by orders of magnitude, the data rates which need to be sustained on the down-link or cross-link transmission channels. Since these channels are severely limited in capacity, the need arises to perform on-board compression to reduce the volume of data which would need to be down-linked. This paper discusses the development and refinement of a low complexity lossy spectral/spatial compression method which provides high compression ratios at low levels of distortion. The developed techniques uses pixels in adjacent bands to predict the intensity of pixels in the band being compressed via a simple linear prediction model. This prediction method when combined with a low-distortion discrete cosine transform (DCT) block coding method yields performance comparable to block-adaptive Karhunen-Loeve Transform (KLT)-DCT methods without incurring the complexity penalty of the KLT. The methods' performance suffers under misregistration. A fractional-pixel interpolation enhancement to the basic technique significantly improves the performance in the case of misregistered bands  相似文献   
9.
In the present study of gas–liquid contactors, mean residence/contact time was calculated from knowledge of superficial velocity and the gas phase hold-up, for various gas rates and impeller geometry and speeds, and compared with values obtained from RTD measurements. A new correlation, involving Flow Number, Froude Number, system geometry and the physical properties, is proposed. This uses the authors data and those available in literature.  相似文献   
10.
A transformational approach for proving termination of parallel logic programs such as GHC programs is proposed. A transformation from GHC programs to term rewriting systems is developed; it exploits the fact that unifications in GHC-resolution correspond to matchings. The termination of a GHC program for a class of queries is implied by the termination of the resulting rewrite system. This approach facilitates the applicability of a wide range of termination techniques developed for rewrite systems in proving termination of GHC programs. The method consists of three steps: (a) deriving moding information from a given GHC program, (b) transforming the GHC program into a term rewriting system using the moding information, and finally (c) proving termination of the resulting rewrite system. Using this method, the termination of many benchmark GHC programs such as quick-sort, merge-sort, merge, split, fair-split and append, etc., can be proved. This is a revised and extended version of Ref. 12). The work was partially supported by the NSF Indo-US grant INT-9416687 Kapur was partially supported by NSF Grant nos. CCR-8906678 and INT-9014074. M. R. K. Krishna Rao, Ph.D.: He currently works as a senior research fellow at Griffith University, Brisbane, Australia. His current interests are in the areas of logic programming, modular aspects and noncopying implementations of term rewriting, learning logic programs from examples and conuterexamples and dynamics of mental states in rational agent architectures. He received his Ph.D in computer science from Tata Institute of Fundamental Research (TIFR), Bombay in 1993 and worked at TIFR and Max Planck Institut für Informatik, Saarbrücken until January 1997. Deepak Kapur, Ph.D.: He currently works as a professor at the State University of New York at Albany. His research interests are in the areas of automated reasoning, term rewriting, constraint solving, algebraic and geometric reasoning and its applications in computer vision, symbolic computation, formal methods, specification and verification. He obtained his Ph.D. in Computer Science from MIT in 1980. He worked at General Electric Corporate Research and Development until 1987. Prof. Kapur is the editor-in-chief of the Journal of Automated Reasoning. He also serves on the editorial boards of Journal of Logic Programming, Journal on Constraints, and Journal of Applicable Algebra in Engineering, Communication and Computer Science. R. K. Shyamasundar, Ph.D.: He currently works as a professor at Tata Institute of Fundamental Research (TIFR), Bombay. His current intersts are in the areas of logic programming, reactive and real time programming, constraint solving, formal methods, specification and verification. He received his Ph.D in computer science from Indian Institute of Science, Bangalore in 1975 and has been a faculty member at Tata Institute of Fundamental Research since then. He has been a visiting/regular faculty member at Technological University of Eindhoven, University of Utrecht, IBM TJ Watson Research Centre, Pennsylvania State University, University of Illinois at Urbana-Champaign, INRIA and ENSMP, France. He has served on (and chaired) Program Committees of many International Conferences and has been on the Editorial Committees.  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