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   96412篇
  免费   1982篇
  国内免费   511篇
电工技术   966篇
综合类   2378篇
化学工业   14772篇
金属工艺   5087篇
机械仪表   3476篇
建筑科学   2666篇
矿业工程   579篇
能源动力   2051篇
轻工业   4843篇
水利工程   1410篇
石油天然气   558篇
武器工业   4篇
无线电   10524篇
一般工业技术   18676篇
冶金工业   3132篇
原子能技术   344篇
自动化技术   27439篇
  2024年   67篇
  2023年   267篇
  2022年   555篇
  2021年   916篇
  2020年   778篇
  2019年   831篇
  2018年   15110篇
  2017年   13952篇
  2016年   10632篇
  2015年   1086篇
  2014年   997篇
  2013年   1594篇
  2012年   4005篇
  2011年   10264篇
  2010年   8857篇
  2009年   6114篇
  2008年   7159篇
  2007年   8093篇
  2006年   417篇
  2005年   1400篇
  2004年   1304篇
  2003年   1328篇
  2002年   658篇
  2001年   191篇
  2000年   273篇
  1999年   143篇
  1998年   193篇
  1997年   149篇
  1996年   149篇
  1995年   78篇
  1994年   70篇
  1993年   73篇
  1992年   65篇
  1991年   63篇
  1990年   48篇
  1989年   36篇
  1988年   38篇
  1986年   39篇
  1985年   34篇
  1968年   45篇
  1967年   34篇
  1966年   42篇
  1965年   44篇
  1960年   30篇
  1959年   35篇
  1958年   37篇
  1957年   36篇
  1956年   34篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
11.
Journal of Materials Science: Materials in Electronics - Nano Mn0.95M0.05S (M ≡ Cu, Mg) samples were produced using molten salt solid state reaction method. Rietveld analysis of X-ray...  相似文献   
12.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
13.
14.
Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system...  相似文献   
15.
Mahdavi  Ali 《Water Resources Management》2019,33(10):3615-3631
Water Resources Management - This work presents an analytical solution for the linearized Boussinesq equation describing the nature of well hydraulics in equilateral triangular-shaped unconfined...  相似文献   
16.
This paper deals with the problem of designing a robust static output feedback controller for polytopic systems. The current research that tackled this problem is mainly based on LMI method, which is conservative by nature. In this paper, a novel approach is proposed, which considers the design space of the controller parameters and iteratively partitions the space to small simplexes. Then, by assessing the stability in each simplex, the solution space for design parameters is directly determined. It has been theoretically proved that, if there exists a feasible solution in the design space, the algorithm can find it. To validate the result of the proposed approach, comparative simulation examples are given to illustrate the performance of the design methodology as compared to those of previous approaches.  相似文献   
17.
18.
19.
This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
20.
Solubility is one of the most indispensable physicochemical properties determining the compatibility of components of a blending system. Research has been focused on the solubility of carbon dioxide in polymers as a significant application of green chemistry. To replace costly and time-consuming experiments, a novel solubility prediction model based on a decision tree, called the stochastic gradient boosting algorithm, was proposed to predict CO2 solubility in 13 different polymers, based on 515 published experimental data lines. The results indicate that the proposed ensemble model is an effective method for predicting the CO2 solubility in various polymers, with highly satisfactory performance and high efficiency. It produces more accurate outputs than other methods such as machine learning schemes and an equation of state approach.  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