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   24564篇
  免费   2389篇
  国内免费   939篇
电工技术   1252篇
综合类   1311篇
化学工业   4883篇
金属工艺   1000篇
机械仪表   1293篇
建筑科学   1248篇
矿业工程   414篇
能源动力   1107篇
轻工业   2110篇
水利工程   382篇
石油天然气   481篇
武器工业   99篇
无线电   3556篇
一般工业技术   3729篇
冶金工业   1498篇
原子能技术   357篇
自动化技术   3172篇
  2024年   56篇
  2023年   258篇
  2022年   525篇
  2021年   730篇
  2020年   554篇
  2019年   611篇
  2018年   727篇
  2017年   677篇
  2016年   814篇
  2015年   925篇
  2014年   1172篇
  2013年   1608篇
  2012年   1565篇
  2011年   1711篇
  2010年   1513篇
  2009年   1450篇
  2008年   1444篇
  2007年   1304篇
  2006年   1211篇
  2005年   997篇
  2004年   947篇
  2003年   1005篇
  2002年   1260篇
  2001年   1057篇
  2000年   642篇
  1999年   510篇
  1998年   469篇
  1997年   389篇
  1996年   311篇
  1995年   231篇
  1994年   162篇
  1993年   137篇
  1992年   103篇
  1991年   95篇
  1990年   91篇
  1989年   94篇
  1988年   52篇
  1987年   63篇
  1986年   60篇
  1985年   55篇
  1984年   35篇
  1983年   31篇
  1982年   19篇
  1981年   26篇
  1980年   26篇
  1979年   16篇
  1978年   20篇
  1977年   26篇
  1976年   32篇
  1975年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
This paper presents a general method to formulate monotonically convergent algorithms for identifying optimal control fields to manipulate quantum dynamics phenomena beyond the linear dipole interaction. The method, facilitated by a field-dependent dipole moment operator, is based on an integral equation of the first kind arising from the Heisenberg equation of motion for tracking a time-dependent, dynamical invariant observable associated with a reference control field.  相似文献   
53.
By exploiting the unattended nature of the wireless sensor networks, an attacker can physically capture and compromise sensor nodes and then launch a variety of attacks. He can additionally create many replicas of a few compromised nodes and spread these replicas over the network, thus launching further attacks with their help. In order to minimize the damage incurred by compromised and replicated nodes, it is very important to detect such malicious nodes as quickly as possible. In this review article, we synthesize our previous works on node compromise detection in sensor networks while providing the extended analysis in terms of performance comparison to the related work. More specifically, we use the methodology of the sequential analysis to detect static and mobile compromised nodes, as well as mobile replicated nodes in sensor networks. With the help of analytical and simulation results, we also demonstrate that our schemes provide robust and efficient node compromise detection capability.  相似文献   
54.
To improve the ability of agent for handling emotions, a new architecture for emotion agent is presented, based on the traditional BDI agent model and the rough set theory. By a new emotional reasoning algorithm based on rough set, the architecture performs emotion reasoning and implements the emotion treatment. An emotional agent grid based on this architecture has been realized, experiment results show that it is efficient to transact simple emotions by emotional agents.  相似文献   
55.
56.
基于Windows Media的网络媒体服务系统的实现   总被引:6,自引:0,他引:6  
介绍了Windows Media系统的体系结构和通信协议,构建了采用Windows Media技术的网络媒体服务系统,详细叙述了系统的连接、配置和技术要点,以较低的代价实现了媒体服务系统的应用。  相似文献   
57.
Photolithography to produce TiO2 patterns from amorphous films of (5-C5H5)2Ti(N3)2 has been demonstrated. The efficiency of the reaction has been measured yielding a quantum yield of 0.025. The mechanism of the photoreactions of (5-C5H5)2Ti(N3)2 has been studied using Fourier transform-infrared spectroscopy in both a low-temperature 1,2-epoxyethylbenzene glass and as surface films. In each case the primary photochemical process was found to be loss of a single azido group. The result of subsequent photolysis was found to be dependent upon medium and temperature. In the low-temperature glass no further photochemistry was observed. The exhaustive photolysis of films at 20 K, or room temperature, under a vacuum or in air led to loss of all ligands and the formation of TiO2.  相似文献   
58.
The H almost disturbance decoupling problem is considered. In this paper, a nonlinear design is proposed to find a state feedback controller for bilinear systems. The closed‐loop system is internally stable and achieves disturbance attenuation in nonlinear H sense. We defined a special form of Lyapunov function, which is constructed in terms of one or a set of positive definite constant matrices. If, except of the origin of system, the corresponding polynomial of the positive definite matrix (or several polynomials relevant to the positive definite constant matrices) has (have) no zero on a given subset of state space, then we can construct a controller to solve our problem. It is found that the controller structure could be complicated, but is feasible in computation and may require optimization technique to search the solution. We consider both SIMO and MIMO cases with illustrated examples.  相似文献   
59.
60.
In this study, a simple method for the fabrication of high aspect ratio silicon nanoporous arrays is developed. A N-type silicon wafer is used as the substrate material. A micro-scale pattern of the desired porous array is transferred to the front surface of the silicon wafer by photolithography after which the wafer is placed in a home-made fixture to efficiently expel the etching generated air and promptly hold the back-side illumination light. A halogen lamp is used as the light source for backside illumination to enhance the electron–hole pair generation. An anodization process is then carried out using a new etchant consisting of hydrofluoric acid and mixed EtOH and EMSO surfactant to effectively polish the pore surfaces and sharpen the tips of the etched pores. A nanochannel array with a nano-tip of 61.4?nm is obtained.  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