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   49206篇
  免费   5542篇
  国内免费   4256篇
电工技术   6708篇
综合类   5118篇
化学工业   7087篇
金属工艺   1559篇
机械仪表   1886篇
建筑科学   5260篇
矿业工程   2261篇
能源动力   1673篇
轻工业   5425篇
水利工程   2649篇
石油天然气   1982篇
武器工业   435篇
无线电   2342篇
一般工业技术   4760篇
冶金工业   1195篇
原子能技术   310篇
自动化技术   8354篇
  2024年   315篇
  2023年   1001篇
  2022年   1372篇
  2021年   1676篇
  2020年   1922篇
  2019年   1891篇
  2018年   1727篇
  2017年   1902篇
  2016年   2043篇
  2015年   2044篇
  2014年   2853篇
  2013年   3307篇
  2012年   3320篇
  2011年   3569篇
  2010年   2612篇
  2009年   2981篇
  2008年   2679篇
  2007年   3157篇
  2006年   2834篇
  2005年   2424篇
  2004年   2083篇
  2003年   1628篇
  2002年   1394篇
  2001年   1182篇
  2000年   1077篇
  1999年   1030篇
  1998年   809篇
  1997年   709篇
  1996年   625篇
  1995年   516篇
  1994年   457篇
  1993年   365篇
  1992年   354篇
  1991年   236篇
  1990年   169篇
  1989年   136篇
  1988年   97篇
  1987年   75篇
  1986年   60篇
  1985年   36篇
  1984年   63篇
  1983年   48篇
  1982年   57篇
  1981年   29篇
  1980年   30篇
  1979年   33篇
  1978年   23篇
  1977年   14篇
  1975年   4篇
  1951年   10篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
91.
In this study, a multistage stochastic programming (SP) model is presented for a variant of single-vehicle routing problem with stochastic demands from a dynamic viewpoint. It is assumed that the actual demand of a customer becomes known only when the customer is visited. This problem falls into the category of SP with endogenous uncertainty and hence, the scenario tree is decision-dependent. Therefore, nonanticipativity of decisions is ensured by conditional constraints making up a large portion of total constraints. Thus, a novel approach is proposed that considerably reduces the problem size without any effect on the solution space. Computational results on some test problems are reported.  相似文献   
92.
Recent developments in the exfoliation, dispersion, and processing of pristine graphene (i.e., non‐oxidized graphene) are described. General metrics are outlined that can be used to assess the quality and processability of various “graphene” products, as well as metrics that determine the potential for industrial scale‐up. The pristine graphene production process is categorized from a chemical engineering point of view with three key steps: i) pretreatment, ii) exfoliation, and iii) separation. How pristine graphene colloidal stability is distinct from the exfoliation step and is dependent upon graphene interactions with solvents and dispersants are extensively reviewed. Finally, the challenges and opportunities of using pristine graphene as nanofillers in polymer composites, as well as as building blocks for macrostructure assemblies are summarized in the context of large‐scale production.  相似文献   
93.
土坡稳定分析中的孔隙水压力估算   总被引:2,自引:0,他引:2  
  相似文献   
94.
In this paper, we present a new sufficient condition for absolute stability of Lure system with two additive time-varying delay components. This criterion is expressed as a set of linear matrix inequalities (LMIs), which can be readily tested by using standard numerical software. We use this new criterion to stabilize a class of nonlinear time-delay systems. Some numerical examples are given to illustrate the applicability of the results using standard numerical software.  相似文献   
95.
A stochastic differential equation involving both a Wiener process and fractional Brownian motion, with nonhomogeneous coefficients and random initial condition, is considered. The coefficients and initial condition depend on a parameter. The assumptions on the coefficients and the initial condition supplying continuous dependence of the solution on a parameter, with respect to the Besov space norm, are established.  相似文献   
96.
This paper addresses the problems of stability and synchronization for a class of Markovian jump neural networks with partly unknown transition probabilities. We first study the stability analysis problem for a single neural network and present a sufficient condition guaranteeing the mean square asymptotic stability. Then based on the Lyapunov functional method and the Kronecker product technique, the chaos synchronization problem of an array of coupled networks is considered. Both the stability and the synchronization conditions are delay-dependent, which are expressed in terms of linear matrix inequalities. The effectiveness of the developed methods is shown by simulation examples.  相似文献   
97.
Robust predictive control handles constrained systems that are subject to stochastic uncertainty but propagating the effects of uncertainty over a prediction horizon can be computationally expensive and conservative. This paper overcomes these issues through an augmented autonomous prediction formulation, and provides a method of handling probabilistic constraints and ensuring closed loop stability through the use of an extension of the concept of invariance, namely invariance with probability p.  相似文献   
98.
This paper addresses the stability issue of discrete-time switched systems with guaranteed dwell-time. The approach of switched homogeneous Lyapunov function of higher order is formally proposed. By means of this approach, a necessary and sufficient condition is established to check the exponential stability of the considered system. With the observation that switching signal is actually arbitrary if the dwell time is one sample time, a necessary and sufficient condition is also presented to verify the exponential stability of switched systems under arbitrary switching signals. Using the augmented argument, a necessary and sufficient exponential stability criterion is given for discrete-time switched systems with delays. A numerical example is provided to show the advantages of the theoretical results.  相似文献   
99.
100.
We investigate asymptotic behavior of the C0-semigroup T(t) associated with the mono-tubular heat exchanger equation with output feedback by a perturbation method. It is shown that T(t) is bounded if a constraint is satisfied by the parameters and the spatial distribution function. Further, applying the Arendt-Batty-Lyubich-Vu theorem, a criterion is established to judge strong stability of T(t).  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