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   1069篇
  免费   53篇
  国内免费   19篇
电工技术   61篇
综合类   1篇
化学工业   296篇
金属工艺   41篇
机械仪表   38篇
建筑科学   23篇
能源动力   65篇
轻工业   72篇
水利工程   2篇
石油天然气   1篇
无线电   88篇
一般工业技术   217篇
冶金工业   68篇
原子能技术   37篇
自动化技术   131篇
  2023年   11篇
  2022年   32篇
  2021年   54篇
  2020年   29篇
  2019年   31篇
  2018年   37篇
  2017年   24篇
  2016年   43篇
  2015年   25篇
  2014年   45篇
  2013年   79篇
  2012年   53篇
  2011年   90篇
  2010年   56篇
  2009年   56篇
  2008年   57篇
  2007年   43篇
  2006年   34篇
  2005年   40篇
  2004年   20篇
  2003年   23篇
  2002年   29篇
  2001年   18篇
  2000年   14篇
  1999年   22篇
  1998年   30篇
  1997年   21篇
  1996年   19篇
  1995年   8篇
  1994年   13篇
  1993年   12篇
  1992年   3篇
  1991年   4篇
  1990年   4篇
  1989年   3篇
  1988年   5篇
  1987年   4篇
  1986年   5篇
  1985年   7篇
  1984年   14篇
  1983年   4篇
  1982年   1篇
  1981年   6篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   4篇
  1974年   1篇
  1968年   1篇
排序方式: 共有1141条查询结果,搜索用时 15 毫秒
1.
2.
The World Robot Summit is a robot Olympics and aims to be held in a different country every four years from 2020. The concept of the Plant Disaster Prevention challenge is daily inspections, checks, and emergency response in industrial plants, and in this competition, robots must carry out these types of missions in a mock-up plant. The concept of the Tunnel Disaster Response and Recovery challenge is emergency response to tunnel disasters, and is a simulation competition whereby teams compete to show their ability to deal with disasters, by collecting information and removing debris. The Standard Disaster Robotics challenge assesses, in the form of a contest, the standard performance levels of a robot that are necessary for disaster prevention and emergency response. The World Robot Summit Preliminary Competition was held at Tokyo Big Sight in October 2018, and 36 teams participated in the Disaster Robotics Category. UGVs and UAVs contended the merits of new technology for solving complex problems, using core technologies such as mobility, sensing, recognition, performing operations, human interface, autonomous intelligence etc., as well as system integration and implementation of strategies for completing missions, gaining high-level results.  相似文献   
3.
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   
4.
Specimens of partially stabilized zirconia were slip cast from aqueous suspensions and sintered at 1500°C for 3 h. The relative density of the cast specimens and the firing shrinkage of the sintered specimens depend on the milling time for the suspension. Vickers hardness and KIC values of 11.46±s0.07 GN/m2 and 6.10 ±0.04 MN.m3/2, respectively, were obtained for all sintered specimens. The dispersion of the suspension is important in increasing the relative density of the cast specimens.  相似文献   
5.
The reliability of InP-based HEMTs is studied, focussing on how it is affected by the doped layer material and gate recess structure. Bias-and-temperature stress tests reveal that fluorine-induced donor passivation in the recess region, formed adjacent to the gate electrode, causes the source resistance (Rs) to increase at large drain bias voltages. The increase in Rs can be prevented by using InP or InAlP as the carrier supply layer material instead of InAlAs. On the other hand, the increase in the drain resistance (Rd) does not depend on the material of the carrier supply layer, which suggests that a mechanism different from that in the case of Rs should be considered. It is also found that a deep gate recess suppresses the increase in Rd after long-term stressing.  相似文献   
6.
In the drying of coated films with dispersed pigments, such as floppy disks, the structure of the film is formed during the drying process and depends on the drying condition. It is important to understand the structure formation during drying for the design of the dryer and die better quality of the product. We measured die drying characteristics of the film and determined the structure of dried film experimentally. A qualitative model for the structure formation during drying of the coated film is suggested.  相似文献   
7.
We have previously found that thymic B cells, particularly thymic CD5+ B cells, show low responsiveness to the usual B cell stimulants such as lipopolysaccharide or anti-IgM plus interleukin (IL)-4, although they proliferate and produce antibodies after direct interaction with major histocompatibility complex class II-restricted T blasts. These findings raise the possibility that a CD40-CD40 ligand (L) interaction is involved in the activation of thymic B cells. In the present study, we therefore examine this possibility using CD40L-transfected Chinese hamster ovary (CHO) cells or anti-CD40 monoclonal antibody (mAb). When B cells in the spleen and peritoneal cavity were stimulated, they proliferated and produced immunoglobulin (Ig) in the presence of CD40L-CHO cells or anti-CD40 mAb alone. However, another signal delivered by IL-10 in addition to CD40L-CHO cells or anti-CD40 mAb was found to be necessary for thymic B cells to proliferate and secrete Ig. Other interleukins acting on B cells, such as IL-4, IL-5, and IL-6, had no effect on the activation of thymic B cells, which thus have unique characteristics not found in peripheral B cells. This report discusses the physiological significance of IL-10- and CD40-driven signals in the activation of thymic B cells.  相似文献   
8.
Recently, many research projects and competitions have attempted to find an autonomous mobile robot that can drive in the real world. In this article, we consider a path-planning method for an autonomous mobile robot that would be safe in a real environment. In such a case, it is very important for the robot to be able to identify its own position and orientation in real time. Therefore, we applied a localization method based on a particle filter. Moreover, in order to improve the safety of such autonomous locomotion, we improved the path-planning algorithm and the generation of the trajectory so that it can consider a region with a limited maximum velocity. In order to demonstrate the validity of the proposed method, we participated in the Real World Robot Challenge 2010. The experimental results are given.  相似文献   
9.
10.
The microphase separation structure in the molten state and the structure formation in crystallization from such ordered melt were investigated for the blends of polystyrene–polyethylene block copolymers (SE) with polystyrene homopolymer (PS) and polyethylene homopolymer (PE) and for the blends consisting of two kinds of SE with different copolymer compositions from each other, using synchrotron small-angle X-ray scattering techniques (SAXS). The copolymer compositions of SE block copolymers employed were 0.34, 0.58 and 0.73 wt. fraction of PE, and their melt morphologies were cylindrical, lamellar and lamellar, respectively. Macrophase separation or the morphology change in the melt occurred depending on the molecular weight and the blend composition, as reported so far. In crystallization from such macrophase-separated and microphase-separated melts, the melt morphology was completely kept for all the blends. Crystallization behavior was also investigated for the blends. The crystallization within the spherical and cylindrical domains surrounded by glassy PS was not observed for SE/PS blends. In the crystallization from the macrophase-separated melt, two exothermal peaks were observed in the DSC measurements, while a single peak was observed for other blends. For the blends with PS, the degree of crystallinity was depressed and the apparent activation energy of crystallization was high, compared to those for the corresponding neat SE. For SE/PE and SE/SE blends, those were changed depending on the blend composition.  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