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   3830篇
  免费   183篇
  国内免费   7篇
电工技术   57篇
综合类   7篇
化学工业   907篇
金属工艺   176篇
机械仪表   70篇
建筑科学   116篇
矿业工程   21篇
能源动力   116篇
轻工业   327篇
水利工程   26篇
石油天然气   19篇
无线电   368篇
一般工业技术   705篇
冶金工业   378篇
原子能技术   35篇
自动化技术   692篇
  2023年   41篇
  2022年   122篇
  2021年   139篇
  2020年   83篇
  2019年   98篇
  2018年   103篇
  2017年   99篇
  2016年   134篇
  2015年   93篇
  2014年   143篇
  2013年   253篇
  2012年   204篇
  2011年   261篇
  2010年   188篇
  2009年   183篇
  2008年   190篇
  2007年   182篇
  2006年   157篇
  2005年   119篇
  2004年   110篇
  2003年   98篇
  2002年   93篇
  2001年   49篇
  2000年   50篇
  1999年   59篇
  1998年   58篇
  1997年   59篇
  1996年   48篇
  1995年   43篇
  1994年   33篇
  1993年   35篇
  1992年   27篇
  1991年   17篇
  1990年   19篇
  1989年   25篇
  1988年   32篇
  1987年   24篇
  1986年   17篇
  1985年   27篇
  1984年   22篇
  1983年   20篇
  1982年   22篇
  1981年   14篇
  1980年   20篇
  1979年   24篇
  1978年   20篇
  1977年   18篇
  1976年   23篇
  1975年   19篇
  1973年   13篇
排序方式: 共有4020条查询结果,搜索用时 0 毫秒
21.
Working collaboratively, psychologist educators and trainers at the doctoral, internship, and postdoctoral levels; credentialers; practitioners; and students offer 8 proposals for psychologists to consider in recognizing, assessing, and intervening with problems of professional competence in students and practicing professionals. In the proposals, the authors address the following topics: definitions and categories; preparing the system; self-assessment; remediation; diversity; communication across various levels of the system; confidentiality; and ethical, regulatory, and legal underpinnings. They also propose future directions for the assessment of problems in professional competence in both students and practicing psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
23.
24.
We isolated a mutant defective in C-terminal farnesyl cysteine:carboxyl methyltransferase activity from a screen for mutations causing a -specific sterility. A genomic fragment was cloned from a yeast multi-copy library that restored mating. Both the cloned gene and the sterile mutation were allelic to the STE14 gene. A ste14-complementing 2·17 kb BamHI fragment subclone was sequenced and found to encode a 239 amino acid protein with a molecular weight of 27,887 Daltons. The hydrophobicity profile of the methyltransferase reveals the presence of at least five potential transmembrane domains. In comparisons of the C-terminal methyltransferase amino acid sequence with those in the PIR and Swiss protein databases, no significantly similar sequences were found nor were conserved regions from other methyltransferases present.  相似文献   
25.
This paper describes the development of a conceptual model of an interaction system for future human-computer interaction. It is suggested that an integrated system is the most promising solution for diverse users and tasks. A ' hybrid interaction system' is considered, which tries to efficiently direct manipulation, menu selection, and natural language. The mechanism of the natural language interface module is described in more detail. Finally, the allocation of functionalities for generalized tasks on the conceptual model is considered from the taxonomic approach.  相似文献   
26.
27.
Commemorates G. M. Haslerud, who died suddenly on April 10, 1990. In his doctoral dissertation (1934) he addressed free and prescribed maze patterns in rats, pointing to a lifetime interest in creative transfer. In 1972 he completed his magnum opus, Transfer, Memory, and Creativity: After-Learning as Perceptual Process, which reflects continuing conversations with his mentor, Robert Yerkes. Haslerud is remembered as a co-founder of the New Hampshire Psychological Association. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
To improve the spectrum efficiency of integrated voice and data services in Personal Communication System (PCS), several reservation-type multiple access schemes, such as Packet Reservation Multiple Access (PRMA), Dynamic Time Division Multiple Access (D-TDMA), Resource Auction Multiple Access (RAMA), etc., have been proposed. PRMA uses the data packet itself to make a channel reservation, and is inefficient in that each unsuccessful reservation wastes one slot. However, it does not have a fixed reservation overhead and offers shorter access delay. On the other hand, fixed reservation overhead is unavoidable in both RAMA and D-TDMA. Compared to D-TDMA and PRMA, RAMA is superior in the sense that its slot assignment is independent of the traffic load. But its implementation is difficult. With these observations, a new reservation protocol, called Dynamic Reservation Multiple Access (DRMA), is proposed in this paper. With this new protocol, the success probability of channel access is greatly improved at the expense of slightly increased system complexity. It solves the problem of inefficiency in PRMA, but without introducing the fixed reservation overhead as in D-TDMA and RAMA. In addition, it is more suited to the dynamic behavior of the integrated traffic because there is no fixed boundary between voice and data slots (which is mandatory in D-TDMA and RAMA). Our numerical results indicate that its performance is superior to the existing reservation protocols, especially in the integrated traffic scenario. Moreover, the soft capacity feature is exhibited when the traffic load increases.  相似文献   
29.
An integrated approach of the design and optimization problem of reinforced concrete frames, based on the use of interactive computer graphics is presented. The formulation of the optimization problem in terms of all the design variables and constraints is given. The size of the problem is greatly reduced if reinforcement areas are considered as dependent variables. A fully stressed design method is employed to optimize an automatically generated initial design. Analysis and design results plots, including complete reinforcement drawings, are available to designers, helping them to evaluate the current status of the design and allowing them to direct the entire computation process.  相似文献   
30.
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