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   77854篇
  免费   4179篇
  国内免费   443篇
电工技术   1122篇
综合类   639篇
化学工业   16898篇
金属工艺   1777篇
机械仪表   1799篇
建筑科学   2764篇
矿业工程   353篇
能源动力   2130篇
轻工业   12551篇
水利工程   787篇
石油天然气   697篇
武器工业   71篇
无线电   4104篇
一般工业技术   12128篇
冶金工业   13226篇
原子能技术   455篇
自动化技术   10975篇
  2024年   144篇
  2023年   698篇
  2022年   1622篇
  2021年   2409篇
  2020年   1698篇
  2019年   1923篇
  2018年   2784篇
  2017年   2763篇
  2016年   2982篇
  2015年   2235篇
  2014年   3064篇
  2013年   5668篇
  2012年   4640篇
  2011年   4880篇
  2010年   3939篇
  2009年   3622篇
  2008年   3436篇
  2007年   3133篇
  2006年   2434篇
  2005年   2130篇
  2004年   1772篇
  2003年   1693篇
  2002年   1590篇
  2001年   1240篇
  2000年   1102篇
  1999年   1108篇
  1998年   4269篇
  1997年   2867篇
  1996年   1903篇
  1995年   1186篇
  1994年   939篇
  1993年   951篇
  1992年   407篇
  1991年   370篇
  1990年   301篇
  1989年   305篇
  1988年   289篇
  1987年   264篇
  1986年   231篇
  1985年   268篇
  1984年   243篇
  1983年   183篇
  1982年   213篇
  1981年   246篇
  1980年   258篇
  1979年   130篇
  1978年   124篇
  1977年   389篇
  1976年   786篇
  1973年   119篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Magnetic Resonance Materials in Physics, Biology and Medicine - In this paper, we review the developments of 1H-MR spectroscopic imaging (MRSI) methods designed to investigate prostate cancer,...  相似文献   
992.
This paper proposes an improved sine–cosine algorithm (ISCA) based 2-DOF-PID controller for load frequency control. A three-area test system is built for study, while some physical constraints (nonlinearities) are considered for the investigation of a realistic power system. The proposed method is used as the parameter optimizer of the LFC controller in different scenarios. The 2-DOF-PID controllers are used because of their capability of fast disturbance rejection without significant increase of overshoot in set-point tracking. The 2-DOF-PID controllers’ efficacy is observed by examining the responses with the outcomes obtained with PID and FOPID controllers. The simulation results with the suggested scheme are correlated with some of the existing algorithms, such as SCA, SSA, ALO, and PSO in three different scenarios, i.e., a disturbance in two areas, in three areas, and in the presence of physical constraints. In addition, the study is extended to a four-area power system. Statistical analysis is performed using the Wilcoxon Sign Rank Test (WSRT) on 20 independent runs. This confirms the supremacy of the proposed method.  相似文献   
993.
The Journal of Supercomputing - CMOS technology is facing physical limitations in scaling the manufacturing process. Therefore, to deepen the development of better designs in a smaller area, it is...  相似文献   
994.
The Journal of Supercomputing - This paper presents an energy-efficient design and evaluation of a novel portable device for the automatic correction of presbyopia in human eyes driven by the use...  相似文献   
995.
Sun  Xiaoqing  Wang  Ju  Yi  Sicheng  Hu  Wei 《Microsystem Technologies》2022,28(4):1025-1035
Microsystem Technologies - A novel piezoelectric inertial actuator is developed in this paper, to realize the requirements of large stroke and high output displacement accuracy. This proposed...  相似文献   
996.
Journal of Intelligent Manufacturing - The order batching problem is a combinatorial optimization problem that arises in the warehouse order picking process. In the order batching problem, the aim...  相似文献   
997.
Software Quality Journal - The number of electronic control units (ECU) installed in vehicles is increasingly high. Manufacturers must improve the software quality and reduce cost by proposing...  相似文献   
998.

In this work we study, design, and evaluate computational methods to support interpretation of statutory terms. We propose a novel task of discovering sentences for argumentation about the meaning of statutory terms. The task models the analysis of past treatment of statutory terms, an exercise lawyers routinely perform using a combination of manual and computational approaches. We treat the discovery of sentences as a special case of ad hoc document retrieval. The specifics include retrieval of short texts (sentences), specialized document types (legal case texts), and, above all, the unique definition of document relevance provided in detailed annotation guidelines. To support our experiments we assembled a data set comprising 42 queries (26,959 sentences) which we plan to release to the public in the near future in order to support further research. Most importantly, we investigate the feasibility of developing a system that responds to a query with a list of sentences that mention the term in a way that is useful for understanding and elaborating its meaning. This is accomplished by a systematic assessment of different features that model the sentences’ usefulness for interpretation. We combine features into a compound measure that accounts for multiple aspects. The definition of the task, the assembly of the data set, and the detailed task analysis provide a solid foundation for employing a learning-to-rank approach.

  相似文献   
999.
Neural Computing and Applications - In this paper, we present a recurrent neural system named long short-term cognitive networks (LSTCNs) as a generalization of the short-term cognitive network...  相似文献   
1000.
The effect of Cr3C2 additions on WC–1TiN–5MgO composites by two-step hot-pressing sintering (heated to 1750°C and then immediately cooled to 1575°C with a soaking time of 60?min under a sintering pressure of 50?MPa) was comprehensively investigated. The microstructure was characterized by means of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD). Mechanical properties, such as hardness, transverse rupture strength, and fracture toughness, were measured. The experimental results show that no η-phase or brittle phases such as W2C were formed, and excellent mechanical properties were achieved for 0.6?wt.% Cr3C2 additions with a hardness of 24.76?GPa, a flexural strength of 1257.1?MPa, and a fracture toughness of 10.08?MPa?·?mm1/2. Cr3C2 addition brought about an improvement in the sinterability and contributed to the homogeneous distribution of second phase nanosized MgO. Crack deflection and crack bridging are the major mechanisms contributing to the drastically enhanced flexural strength and fracture toughness.  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