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   32805篇
  免费   2513篇
  国内免费   1321篇
电工技术   1802篇
技术理论   1篇
综合类   1957篇
化学工业   5637篇
金属工艺   1647篇
机械仪表   2164篇
建筑科学   2590篇
矿业工程   1037篇
能源动力   844篇
轻工业   2010篇
水利工程   574篇
石油天然气   2104篇
武器工业   219篇
无线电   3818篇
一般工业技术   3996篇
冶金工业   1622篇
原子能技术   381篇
自动化技术   4236篇
  2024年   176篇
  2023年   588篇
  2022年   902篇
  2021年   1297篇
  2020年   939篇
  2019年   850篇
  2018年   938篇
  2017年   1005篇
  2016年   883篇
  2015年   1179篇
  2014年   1577篇
  2013年   1851篇
  2012年   1972篇
  2011年   2086篇
  2010年   1829篇
  2009年   1791篇
  2008年   1657篇
  2007年   1659篇
  2006年   1811篇
  2005年   1610篇
  2004年   1044篇
  2003年   942篇
  2002年   909篇
  2001年   796篇
  2000年   901篇
  1999年   970篇
  1998年   799篇
  1997年   704篇
  1996年   670篇
  1995年   527篇
  1994年   438篇
  1993年   323篇
  1992年   259篇
  1991年   201篇
  1990年   154篇
  1989年   117篇
  1988年   95篇
  1987年   50篇
  1986年   35篇
  1985年   28篇
  1984年   17篇
  1983年   17篇
  1982年   22篇
  1981年   13篇
  1980年   3篇
  1979年   3篇
  1959年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Xie  Jun  Zhang  Jianwei  Liu  Shuang  Chen  Guohua 《The Journal of supercomputing》2022,78(3):3500-3516
The Journal of Supercomputing - This study was to evaluate the performance of magnetic resonance imaging (MRI) reconstruction algorithm based on convolutional neural network (CNN) in the diagnosis...  相似文献   
62.
63.
64.
65.
本文介绍了滚筒反力式制动检验台制动力的不确定度评定。  相似文献   
66.
Nowadays, heating cables are used as heat sources for heating pavements in practical engineering. However, there is a contradiction between the snow melting function and the interlaminar stability of heating pavement. In order to solve the contradiction, the interlaminar failure behavior of asphalt mixture coupled heating cables specimen (AMCS) was researched, through experiments and the finite element method. Under the different conditions of heating cables and rolling times, a series of direct shear tests was performed at the interface of AMCS, to compare the interlaminar stability of three different AMCS. Meanwhile, based on the bilinear cohesive zone model and coulomb friction model a 2D finite element model was established, to simulate this shear failure processes and make up for the limitations of the experiment. According to above test and simulation results, the failure mechanism and the weakest interface in AMCS were found, and the influence of the heating cable’s diameter and embedded spacing on the interlaminar shear strength were found. Then, a modified coulomb theorem model was proposed to predict the shear strength of the AMCS. This research enriches the design theory of the heating pavement and it has great significance for its structural design of heating asphalt pavement.  相似文献   
67.
68.
The evolution of the dislocation density induced by the nanomachining process dominates the plastic deformation behaviors of materials, thus affecting the mechanical properties significantly. However, a challenging topic related to how to establish an accurate model for predicting the dislocation density based on the limited simulations and experiments arises due to the complicated thermal–mechanical coupling mechanism during the machining process. Herein, a multistage method integrating machine learning, physics, and high-throughput atomic simulation is proposed to investigate the effect of cutting speed on the dislocation behavior in polycrystal copper. Compared with the traditional one-step machine learning method, the constraint of physical features effectively improves the accuracy and generalization ability of the model. The results indicate that the dislocation behaviors depend on the competition between the cutting force and temperature. In the low-cutting speed, the predominated role of the cutting temperature leads to a rapid decline of the dislocation density. In contrast, the dislocation density tends to be stable under a high-speed cutting process due to the dynamic balance between the effects of the cutting force and temperature. Notably, the proposed strategy provides a new and universal framework to design the machining parameters to obtain high-quality products.  相似文献   
69.
A simple theoretical model is presented for the reduction of a singly charged cation under conditions where migration is important and the cation is coupled to a neutral species through a chemical equilibrium, AB = A(+) + B(-). Only the steady-state transport-limited current, I(l), is considered. Simple algebraic equations describe the ratio of I(l) to the diffusion-limited current, I(d), as it depends on the degree of dissociation, determined by the ratio of equilibrium constant to formal concentration, K(AB)/C*(AB). The ratio I(l)/I(d) is found to depend on the ratio of electrolyte to equilibrium concentration of A(+) in bulk solution just as for the well-known result for the case without the equilibrium (i.e., K(AB) → ∞). The results are in accord with published experimental data for weak acids. Agreement and disagreement with other theoretical treatments of this problem are discussed. The main results are for 1:1 supporting electrolytes; extensions are made to 2:1, 1:2, and 2:2 supporting electrolytes.  相似文献   
70.
In order to improve decision-making efficiency about emergency event, this paper proposes a novel concept, i.e., Agile-Delphi Method, which is an integration of agile decision and Delphi Method implicating that the decision-makers instantly deliver, respond, treat, and utilize information via Delphi process while conducting group decision-making about emergency event. The paper details the mechanism of group decision-making about emergency event based on network technology and Agile-Delphi Method. Finally, the paper conducts an empiric analysis taking the “111 event”, i.e., the liquid ammonia spill event happened on November 1, 2006 in a phosphorus chemical company in China, as an example.  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