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   19676篇
  免费   503篇
  国内免费   23篇
电工技术   245篇
综合类   10篇
化学工业   3649篇
金属工艺   293篇
机械仪表   325篇
建筑科学   1120篇
矿业工程   114篇
能源动力   515篇
轻工业   1453篇
水利工程   160篇
石油天然气   194篇
武器工业   1篇
无线电   1134篇
一般工业技术   2977篇
冶金工业   5351篇
原子能技术   167篇
自动化技术   2494篇
  2022年   139篇
  2021年   218篇
  2020年   174篇
  2019年   225篇
  2018年   270篇
  2017年   265篇
  2016年   323篇
  2015年   243篇
  2014年   387篇
  2013年   1125篇
  2012年   680篇
  2011年   891篇
  2010年   693篇
  2009年   680篇
  2008年   868篇
  2007年   892篇
  2006年   698篇
  2005年   740篇
  2004年   574篇
  2003年   576篇
  2002年   526篇
  2001年   347篇
  2000年   312篇
  1999年   348篇
  1998年   700篇
  1997年   519篇
  1996年   436篇
  1995年   402篇
  1994年   347篇
  1993年   368篇
  1992年   285篇
  1991年   186篇
  1990年   248篇
  1989年   304篇
  1988年   223篇
  1987年   231篇
  1986年   227篇
  1985年   290篇
  1984年   267篇
  1983年   237篇
  1982年   227篇
  1981年   224篇
  1980年   180篇
  1979年   193篇
  1978年   184篇
  1977年   213篇
  1976年   229篇
  1975年   187篇
  1974年   165篇
  1973年   138篇
排序方式: 共有10000条查询结果,搜索用时 0 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