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   2679篇
  免费   64篇
  国内免费   3篇
电工技术   28篇
综合类   3篇
化学工业   493篇
金属工艺   50篇
机械仪表   66篇
建筑科学   133篇
矿业工程   4篇
能源动力   81篇
轻工业   225篇
水利工程   13篇
石油天然气   5篇
无线电   205篇
一般工业技术   347篇
冶金工业   773篇
原子能技术   29篇
自动化技术   291篇
  2021年   33篇
  2020年   33篇
  2019年   22篇
  2018年   35篇
  2017年   34篇
  2016年   33篇
  2015年   23篇
  2014年   46篇
  2013年   159篇
  2012年   101篇
  2011年   115篇
  2010年   108篇
  2009年   86篇
  2008年   83篇
  2007年   97篇
  2006年   99篇
  2005年   86篇
  2004年   57篇
  2003年   55篇
  2002年   49篇
  2001年   62篇
  2000年   55篇
  1999年   56篇
  1998年   184篇
  1997年   126篇
  1996年   101篇
  1995年   54篇
  1994年   58篇
  1993年   80篇
  1992年   30篇
  1991年   31篇
  1990年   31篇
  1989年   30篇
  1988年   32篇
  1987年   28篇
  1986年   17篇
  1985年   31篇
  1984年   24篇
  1983年   21篇
  1982年   37篇
  1981年   25篇
  1980年   24篇
  1979年   24篇
  1978年   16篇
  1977年   28篇
  1976年   39篇
  1975年   15篇
  1974年   16篇
  1973年   14篇
  1968年   12篇
排序方式: 共有2746条查询结果,搜索用时 18 毫秒
1.
2.
3.
4.
5.
In this paper we report the use of photothermal techniques such as Thermal lens (TL) spectrometry, Photoacoustic and heat capacity, ρcp, to determine the thermo-optical parameters, such as thermal conductivity (K), thermal diffusivity (D), specific heat (cp) and the optical path dependence with temperature (ds/dT), of an undoped polycrystalline 3C-SiC. To our knowledge, this is the first time that Thermal lens technique is used for wide band-gap systems. Results obtained for the polycrystalline sample with TL technique indicates that ds/dT is negative at room temperature. Moreover, the obtained values of thermal diffusivity and thermal conductivity are in good agreement with that found in the literature, indicating that the phototermal techniques can be used to obtain the referred parameters in circumstances where other techniques cannot be used, for example, in harsh environments.  相似文献   
6.
As the use of navigation systems becomes more widespread, the demand for advanced functions of navigation systems also increases. In the light of user satisfaction, personalisation of route guidance by incorporating user preferences is one of the most desired features. A user model applied to personalised route guidance is presented. The user model adaptively updates route selection rules when it discovers the predicted choice differs from the actual choice of the driver. This study employs a decision tree learning algorithm, the C4.5 algorithm, which has advantages over other data mining methods in terms of its comprehensible model structure. Simulation experiments with a real-world network were conducted to analyse the applicability of the model to adaptive route guidance and the accuracy of its prediction  相似文献   
7.
8.
In this paper we design an experiment which can be depicted as a simple scenario, a very limited 'world'. In this world, there are an actor that can pursue a project and an observer that is keeping its eyes on the actor. We try to show in the experiment that the observer can to some degree understand the actor based on its knowledge and some metaphors, i.e. understand what the actor is doing and why. As the conclusion of this experiment, we try to show some features of 'understanding'. These are (1) that 'understanding' has to be based on some preliminary knowledge; (2) that 'understanding' is a process of incremental learning; (3) that, as for symbolic systems, some metaphors are necessary for mapping real entities into concepts in mind.  相似文献   
9.
Surface expression of the T cell antigen receptor (TCR) in mature T cells requires the association of a variable heterodimer (alpha.beta or gamma.delta) with six invariant CD3 polypeptides (gamma, delta, epsilon-epsilon, zeta-zeta, or zeta-eta). We described here that deletion of the cytoplasmic tail polypeptide sequence (Lys-Lys-Lys-Asn-Ser) of TCR beta-chain (beta CT) results in expression of the truncated beta-chain on the surface of a mature T cell hybridoma line, in the absence of TCR-alpha, as a glycophosphatidylinositol (GPI)-anchored monomeric polypeptide. The GPI-anchored TCR-beta CT is not associated with CD3-epsilon and is incapable of conventional signal transduction. Association with TCR-alpha prevents beta CT from GPI-linkage formation. The alpha beta CT heterodimer binds the CD3 polypeptides, and the resultant TCR alpha beta CT/CD3 complex is capable of signal transduction. Our data show that a signal sequence for GPI-linkage formation is present in TCR-beta, and this alternative membrane anchoring mechanism can be utilized by beta-chain polypeptide lacking the CT sequence. We conclude therefore that in the absence of TCR-alpha expression, the beta-chain CT sequence plays an essential function in hindering GPI-linkage formation, thereby preventing escape of incompletely assembled TCR beta-chain to the cell surface of mature T cells.  相似文献   
10.
A Sketch-Based Interface for Clothing Virtual Characters   总被引:5,自引:0,他引:5  
This interactive system for garment creation determines a garment's shape and how the character wears it based on a user-drawn sketch. The system then uses distances between the 2D garment silhouette and the character model to infer remaining distance variations in 3D  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