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   19023篇
  免费   474篇
  国内免费   19篇
电工技术   251篇
综合类   12篇
化学工业   3833篇
金属工艺   309篇
机械仪表   325篇
建筑科学   1132篇
矿业工程   109篇
能源动力   537篇
轻工业   1450篇
水利工程   163篇
石油天然气   195篇
武器工业   1篇
无线电   1195篇
一般工业技术   3055篇
冶金工业   4200篇
原子能技术   177篇
自动化技术   2572篇
  2022年   148篇
  2021年   225篇
  2020年   178篇
  2019年   238篇
  2018年   276篇
  2017年   270篇
  2016年   327篇
  2015年   243篇
  2014年   404篇
  2013年   1150篇
  2012年   708篇
  2011年   922篇
  2010年   723篇
  2009年   713篇
  2008年   908篇
  2007年   912篇
  2006年   729篇
  2005年   762篇
  2004年   583篇
  2003年   599篇
  2002年   542篇
  2001年   341篇
  2000年   312篇
  1999年   325篇
  1998年   331篇
  1997年   316篇
  1996年   316篇
  1995年   353篇
  1994年   284篇
  1993年   310篇
  1992年   287篇
  1991年   172篇
  1990年   245篇
  1989年   292篇
  1988年   215篇
  1987年   226篇
  1986年   218篇
  1985年   275篇
  1984年   269篇
  1983年   235篇
  1982年   228篇
  1981年   227篇
  1980年   186篇
  1979年   193篇
  1978年   177篇
  1977年   181篇
  1976年   154篇
  1975年   184篇
  1974年   172篇
  1973年   135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
As college students experience the challenges of their classes and extracurricular activities, they undergo a developmental progression in which they gradually relinquish their belief in the certainty of knowledge and the omniscience of authorities and take increasing responsibility for their own learning. At the highest developmental level normally seen in college students (which few attain before graduation), they display attitudes and thinking patterns resembling those of expert scientists and engineers, including habitually and skillfully gathering and analyzing evidence to support their judgments. This paper proposes an instructional model designed to provide a suitable balance of challenge and support to advance students to that level. The model components are (1) variety and choice of learning tasks; (2) explicit communication and explanation of expectations; (3) modeling, practice, and constructive feedback on high‐level tasks; (4) a student‐centered instructional environment; and (5) respect for students at all levels of development.  相似文献   
6.
A key performance parameter of a manufacturing network or supply chain is its cycle time; the time that a typical item spends in the network. A previous simulation study on a semiconductor assembly and test facility showed that cycle times could be reduced by having smooth input and service rates. This suggested that there is a “cycle time principle” that, for a system with a specified throughput or input rate, the shortest cycle times are obtained when the input and service rates do not vary over time. We prove that this principle is true for the M/G/1 and M/M/s queueing systems and Jackson networks. The analysis involves establishing several results on the concavity of waiting time probabilities and the convexity of expected waiting times and queue lengths, as functions of input and service rates. These results also have natural uses in other optimization problems.  相似文献   
7.
可重定位的基于事务的系统级验证   总被引:2,自引:0,他引:2  
功能验证已经成为开发SoC的主要问题。随着一些复杂SoC的规模超过两千万门,以及对开发和集成嵌入式软件的需求持续增加,软件模拟器已经力所不及。在设计过程需要几百万个时钟周期来充分测试和验证软件功能的情况下,软件仿真器的性能下降到1-5Hz。按照这种速率,软件调试需要几年的时  相似文献   
8.
Test Case Generation as an AI Planning Problem   总被引:6,自引:0,他引:6  
While Artificial Intelligence techniques have been applied to a variety of software engineering applications, the area of automated software testing remains largely unexplored. Yet, test cases for certain types of systems (e.g., those with command language interfaces and transaction based systems) are similar to plans. We have exploited this similarity by constructing an automated test case generator with an AI planning system at its core. We compared the functionality and output of two systems, one based on Software Engineering techniques and the other on planning, for a real application: the StorageTek robot tape library command language. From this, we showed that AI planning is a viable technique for test case generation and that the two approaches are complementary in their capabilities.  相似文献   
9.
Management of distributed environments requires corporate IS managers to shift from being operators of a central utility to facilitators who can recognize the synergy among loosely related groups of users. Success depends on the development of new ways of visualizing and measuring the service delivery process.  相似文献   
10.
Carstensen and Rhodes1 have suggested that when, in stability programs, assays cannot be performed immediately after the protocol-designated storage time, then freezing them until such a time when assays can be performed would be a reasonable manner to retain the protocol schedule. They caution, however, that such a procedure may not be valid for dissolution data. The article to follow deals with real-time data showing that such a process is feasible for Nalidixic Acid tablets (and presumably for other tablets as well), and that, furthermore, the dissolution pattern would seem to be “frozen” as well.  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