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   19192篇
  免费   1966篇
  国内免费   1387篇
电工技术   1675篇
技术理论   7篇
综合类   2285篇
化学工业   1017篇
金属工艺   453篇
机械仪表   1682篇
建筑科学   2341篇
矿业工程   671篇
能源动力   608篇
轻工业   374篇
水利工程   514篇
石油天然气   573篇
武器工业   191篇
无线电   2802篇
一般工业技术   2028篇
冶金工业   558篇
原子能技术   93篇
自动化技术   4673篇
  2024年   42篇
  2023年   213篇
  2022年   398篇
  2021年   532篇
  2020年   550篇
  2019年   449篇
  2018年   402篇
  2017年   493篇
  2016年   587篇
  2015年   768篇
  2014年   1329篇
  2013年   1097篇
  2012年   1399篇
  2011年   1618篇
  2010年   1302篇
  2009年   1189篇
  2008年   1226篇
  2007年   1308篇
  2006年   1252篇
  2005年   1087篇
  2004年   925篇
  2003年   812篇
  2002年   598篇
  2001年   607篇
  2000年   477篇
  1999年   394篇
  1998年   267篇
  1997年   251篇
  1996年   192篇
  1995年   167篇
  1994年   119篇
  1993年   106篇
  1992年   91篇
  1991年   63篇
  1990年   50篇
  1989年   37篇
  1988年   45篇
  1987年   24篇
  1986年   16篇
  1985年   10篇
  1984年   13篇
  1983年   8篇
  1982年   3篇
  1981年   4篇
  1980年   4篇
  1979年   5篇
  1975年   2篇
  1964年   3篇
  1957年   1篇
  1956年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
描述了综合线损分析系统应该具有的主要功能和分析内容,介绍了系统实现中应该注意的几个问题、系统内容和实现方法。  相似文献   
102.
麻青梅 《地矿测绘》2003,19(2):34-36
介绍带状大比例尺地形图在分带处高斯平面上拼接的原理和方法,并编制了相应的接边数据处理程序。作业实践说明,该接边方法简便实用,计算程序正确可靠。  相似文献   
103.
绿色供应链管理的基本原理   总被引:39,自引:0,他引:39  
人口、资源与环境三者之间的矛盾日益突显,要求制造业提高其活动与环境的相容性。绿色供应链管理是从系统的观点与集成的思想出发解决制造业与环境之间冲突的有效方式。从可持续发展的思想出发建立了绿色供应链的概念模型,分析了绿色供应链管理的目标,在此基础上探讨了绿色供应链管理的基本原理,认为共生原理、循环原理、替代转换原理与系统开放原理是实施绿色供应链管理应该遵循的基本原理。  相似文献   
104.
通过分析各种冲突解决方法的特点,提出了一种冲突的集成解决方案。采用面向对象的Object Pascal语言编制了一个实例,给出了该方法在零件结构工艺性设计中的具体应用。  相似文献   
105.
Intelligent multisensor surveillance systems consist of several types of sensors, which are installed on fixed and mobile devices. These components provide a huge quantity of information that has to be contrasted, correlated and integrated in order to recognize and react on special situations. These systems work in highly dynamic environments, with severe security and robustness requirements. All these characteristics imply the need for distributed solutions. In these solutions, scattered components can decide and act with some degree of autonomy (for instance, if they become isolated), or cooperate and coordinate for a complete tracking of special situations. In order to cope with these requirements and to better structure the solution, we have decided to design surveillance system control as a multiagent system. This is done by applying an agent-orientated methodology, which is assessed with concrete scenarios.  相似文献   
106.
乳化炸药的乳化物理模型和理想乳化模态   总被引:3,自引:1,他引:2  
文章以平推流模拟了乳化炸药乳胶质的形成过程,并建立了机械强制乳化的物理模型及理想模态。  相似文献   
107.
Currently relational databases are widely used, while object-oriented databases are emerging as a new generation of database technology. This paper presents a methodology to provide effective sharing of information in object-oriented databases and relational databases. The object-oriented data model is selected as a common data model to build an integrated view of the diverse databases. An object-oriented query language is used as a standard query language. A method is developed to transform a relational data definition to an equivalent object-oriented data definition and to integrate local data definitions. Two distributed query processing methods are derived. One is for general queries and the other for a special class of restricted queries. Using the methods developed, it is possible to access distributed object-oriented databases and relational databases such that the locations and the structural differences of the databases are transparent to users.  相似文献   
108.
LOW-CYCLE FATIGUE UNDER NON-PROPORTIONAL LOADING   总被引:4,自引:0,他引:4  
A series of strain-controlled, low-cycle fatigue experiments have been conducted on 42CrMo steel under various loading paths including circular, square, cruciform, and rectangular paths. Present experiments have shown that there is additional hardening under non-proportional cyclic loading. Non-proportional cyclic additional hardening also results in a shorter life for multiaxial low cycle fatigue. A non-proportionality measure of strain path based on both a physical basis and macromechanical phenomena is proposed. The loading path effect on additional hardening is also described well. Low-cycle fatigue damage accumulation and the evolution process under non-proportional loading is analysed via the Continuum Damage Mechanics Model of Chaboche. A non-proportinality measure is introduced in the damage evolution equation and a modified Coffin-Manson type formula is derived. A novel fatigue life prediction approach based on the critical-plane concept of Brown and Miller is proposed.  相似文献   
109.
We consider the problem of integrating XDuce into ML. This is difficult because of incompatible type and value representations. Our solution is a type-driven translation scheme from XDuce to ML based on a structured representation of XDuce values. XDuce type inference guides the insertion of appropriate coercion functions to translate regular expression pattern matching and uses of semantic subtyping. We can extend our translation scheme to include ML function calls and patterns into XDuce. Thus, we can embed XDuce into ML. Our results allow to enrich the ML language with support for dealing with semi-structured data.  相似文献   
110.
In the last decade there was growing interest in strategic management literature about factors that influence a company's ability to use IT. There is general consensus that knowledge and competency are necessary in developing an IT capability, but there is very little understanding of what the necessary competencies are, and how they influence IS usage in different contexts. The small and medium-sized enterprise context is particularly interesting for two reasons: it constitutes a major part of the economy and it has been relatively unsuccessful in exploiting e-business.  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