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   11462篇
  免费   94篇
  国内免费   139篇
电工技术   152篇
综合类   1篇
化学工业   665篇
金属工艺   436篇
机械仪表   84篇
建筑科学   100篇
能源动力   79篇
轻工业   193篇
水利工程   26篇
石油天然气   10篇
武器工业   1篇
无线电   419篇
一般工业技术   307篇
冶金工业   91篇
原子能技术   106篇
自动化技术   9025篇
  2023年   9篇
  2022年   9篇
  2021年   87篇
  2020年   40篇
  2019年   54篇
  2018年   51篇
  2017年   27篇
  2016年   45篇
  2015年   45篇
  2014年   270篇
  2013年   276篇
  2012年   859篇
  2011年   3155篇
  2010年   1213篇
  2009年   1062篇
  2008年   727篇
  2007年   651篇
  2006年   499篇
  2005年   615篇
  2004年   562篇
  2003年   621篇
  2002年   306篇
  2001年   24篇
  2000年   22篇
  1999年   42篇
  1998年   105篇
  1997年   43篇
  1996年   28篇
  1995年   15篇
  1994年   21篇
  1993年   15篇
  1992年   15篇
  1991年   9篇
  1990年   13篇
  1989年   11篇
  1988年   12篇
  1987年   12篇
  1986年   16篇
  1985年   7篇
  1984年   31篇
  1983年   16篇
  1982年   11篇
  1981年   7篇
  1980年   6篇
  1979年   3篇
  1978年   5篇
  1977年   4篇
  1971年   3篇
  1967年   2篇
  1966年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous...  相似文献   
3.
4.
Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.  相似文献   
5.
This paper presents a novel approach to the localization of moving targets in a complex environment based on the measurement of the perturbations induced by the target presence on an independently‐generated time‐varying electromagnetic field. Field perturbations are measured via a set of sensors deployed over the domain of interest and used to detect and track a possible target by resorting to a particle Bernoulli filter (PBF). To comply with real‐time operation, the PBF works along with an artificial neural network (ANN) model of the environment trained offline via finite elements (FEs). The performance of the proposed algorithm is assessed via simulation experiments.  相似文献   
6.
7.
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging.  相似文献   
8.
There are several damping phenomena in quantum optics. Such phenomena have been usually explained by open systems. In statistical physics, open system dynamics have been used to study the irreversibility and the approach to equilibrium. In this paper, the dynamical change of the mutual entropy for an open system, frequently studied in the quantum optics literature, is rigorously computed through a model of quantum Markov chain. In particular, the concrete formula of Stinespring expression for such a model is obtained and applied to the derivation of the mutual entropy, and some computational results are presented.  相似文献   
9.
Adaptive motion control using neural network approximations   总被引:1,自引:0,他引:1  
In this paper, we present a new adaptive technique for tracking control of mechanical systems in the presence of friction and periodic disturbances. Radial Basis Functions (RBFs) are used to compensate for the effects of nonlinearly occurring parameters in the friction and periodic disturbance model. Theoretical analysis, such as stability and transient performance, is provided. Furthermore, the performance of the adaptive RBF controller and its non-adaptive counterpart are compared.  相似文献   
10.
Biodegradable hollow microfibres containing particles loaded with specific active agents can be potentially employed to produce a special kind of substrate for tissue engineering, able to function as a scaffold and at the same time to act as a drug‐releasing system. Biodegradable hollow microfibres based on poly(lactic acid) were produced by a dry–wet spinning procedure. Drug‐loaded microparticles were prepared by a simple oil‐in‐water emulsion and entrapped inside the fibres. The morphology of both fibres and particles was investigated by scanning electron microscopy. The mechanical and thermal properties of the fibres were investigated by tensile tests and differential scanning calorimetry. In vitro tests were performed to evaluate the release of the drug from the fibres loaded with the particles Copyright © 2004 Society of Chemical Industry  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