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   462965篇
  免费   38710篇
  国内免费   22219篇
电工技术   29429篇
技术理论   74篇
综合类   56040篇
化学工业   55914篇
金属工艺   20042篇
机械仪表   24715篇
建筑科学   63078篇
矿业工程   25613篇
能源动力   15549篇
轻工业   30002篇
水利工程   22214篇
石油天然气   21764篇
武器工业   5254篇
无线电   30252篇
一般工业技术   35043篇
冶金工业   26014篇
原子能技术   4193篇
自动化技术   58704篇
  2024年   1757篇
  2023年   5265篇
  2022年   9970篇
  2021年   12638篇
  2020年   12768篇
  2019年   10095篇
  2018年   9608篇
  2017年   11960篇
  2016年   14236篇
  2015年   15545篇
  2014年   28375篇
  2013年   25605篇
  2012年   31860篇
  2011年   34357篇
  2010年   26316篇
  2009年   27129篇
  2008年   25191篇
  2007年   31873篇
  2006年   29700篇
  2005年   26022篇
  2004年   21992篇
  2003年   19523篇
  2002年   16030篇
  2001年   13432篇
  2000年   11376篇
  1999年   9155篇
  1998年   6793篇
  1997年   5988篇
  1996年   5274篇
  1995年   4455篇
  1994年   3920篇
  1993年   2889篇
  1992年   2510篇
  1991年   1851篇
  1990年   1607篇
  1989年   1435篇
  1988年   1050篇
  1987年   726篇
  1986年   558篇
  1985年   511篇
  1984年   447篇
  1983年   340篇
  1982年   282篇
  1981年   225篇
  1980年   194篇
  1979年   143篇
  1978年   80篇
  1977年   89篇
  1976年   66篇
  1975年   69篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
影视后期制作或图像合成中,动态实时改变显示画面的景深能进一步增强画面的真实感,但由于实时性要求较高,软件实现在处理速度方面容易产生瓶颈。为此,采用预处理的办法,分别对前景和背景进行低通滤波,得到前、背景各自的模拟帧序列,通过调节前景和背景帧序列的位置,模拟确定其各自的变焦程度,然后将前景和背景动态合成具有虚拟景深效果的画面。  相似文献   
82.
The aim of this paper is to give a general quantitative requirement which the loop gain must satisfy in order to stabilize a given unstable (possibly nonlinear and time-varying) plant, namely that the gain must exceed one.  相似文献   
83.
结合“98”抗洪抢险实例,对多种险情作了具体分析,通过汛后调查,对抗洪抢险消险措施和效果进行了总结,为今后进一步做好防洪消险工作提供了经验。  相似文献   
84.
聂幼华 《食品与机械》1996,(5):16-18,20
本文对芝麻营养保健成分的提取进行了系统的研究。确定了芝麻营养原液的制取工艺。为充分发挥芝麻的营养保健作用开辟了新的途径。  相似文献   
85.
In this paper we extend the finite-dimensional results for the H-control problem with measurement-feedback to a large class of infinite-dimensional systems, allowing for a certain type of unboundedness in the input and output operators (the Pritchard-Salamon class). The main result of the paper relates the solvability to the suboptimal H-control problem to the existence of stabilizing solutions to certain operator Riccati equations. Furthermore, a characterization of all suboptimal controllers is given.  相似文献   
86.
New requirements of growing computer networks and information systems have an influence on extended client/server models with increased functionality. This forms the basis for service management in distributed systems which is realized by a service trading concept. This paper studies the requirements derived from the Open Distributed Processing (ODP) Reference Model in order to consider an open service market. Furthermore, it examines management possibilities for describing the service trading scenario. Because of similar architectures and properties ODP services, service offers, types, exporters and traders are mapped onto management components and modeled as managed objects. Therefore, the Guidelines for the Definition of Managed Objects (GDMO) are used. The final concept allows a precise and unambiguous study of the service trading scenario and provides means for exporting and importing of service offers in a distributed environment.  相似文献   
87.
We introduce a semantic data model to capture the hierarchical, spatial, temporal, and evolutionary semantics of images in pictorial databases. This model mimics the user's conceptual view of the image content, providing the framework and guidelines for preprocessing to extract image features. Based on the model constructs, a spatial evolutionary query language (SEQL), which provides direct image object manipulation capabilities, is presented. With semantic information captured in the model, spatial evolutionary queries are answered efficiently. Using an object-oriented platform, a prototype medical-image management system was implemented at UCLA to demonstrate the feasibility of the proposed approach.  相似文献   
88.
Work system improvements are implemented in various manufacturing processes to prevent problems caused by human errors. However, they are almost always applied to problems which have already occurred. This paper examines a method of identifying latent human errors existing within the work systems beforehand. A procedure for applying failure mode and effect analysis to this identification problem was defined based on over 1000 empirical errors: a work system decomposition criterion and fundamental error modes for listing latent human errors, and then applied to three practical manufacturing processes in order to evaluate its effectiveness.  相似文献   
89.
EEPROM的参数设置控制着系统的基本功能,设置的改变对系统的起动和运行起着重要作用。本文详细地列出了EEPROM的地址分配表,并通过上机实验对那些重要的地址了详细的说明。  相似文献   
90.
This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate.  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