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   87184篇
  免费   6276篇
  国内免费   2880篇
电工技术   4385篇
技术理论   9篇
综合类   4818篇
化学工业   15068篇
金属工艺   4673篇
机械仪表   5333篇
建筑科学   7023篇
矿业工程   1977篇
能源动力   2537篇
轻工业   4973篇
水利工程   1458篇
石油天然气   4487篇
武器工业   495篇
无线电   10651篇
一般工业技术   11395篇
冶金工业   4859篇
原子能技术   821篇
自动化技术   11378篇
  2024年   143篇
  2023年   1251篇
  2022年   1710篇
  2021年   2921篇
  2020年   2302篇
  2019年   2005篇
  2018年   2243篇
  2017年   2508篇
  2016年   2357篇
  2015年   2941篇
  2014年   4018篇
  2013年   5138篇
  2012年   5306篇
  2011年   5576篇
  2010年   4966篇
  2009年   4753篇
  2008年   4540篇
  2007年   4461篇
  2006年   4724篇
  2005年   4183篇
  2004年   2861篇
  2003年   2551篇
  2002年   2242篇
  2001年   2049篇
  2000年   2294篇
  1999年   2570篇
  1998年   2432篇
  1997年   1892篇
  1996年   1753篇
  1995年   1475篇
  1994年   1261篇
  1993年   964篇
  1992年   718篇
  1991年   570篇
  1990年   420篇
  1989年   389篇
  1988年   340篇
  1987年   196篇
  1986年   195篇
  1985年   132篇
  1984年   113篇
  1983年   71篇
  1982年   76篇
  1981年   64篇
  1980年   46篇
  1979年   46篇
  1977年   47篇
  1962年   56篇
  1961年   59篇
  1960年   59篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
The RNA methylase METTL3 catalyzes the transfer of a methyl group from the cofactor S-adenosyl-L-methionine (SAM) to the N6 atom of adenine. We have screened a library of 4000 analogues and derivatives of the adenosine moiety of SAM by high-throughput docking into METTL3. Two series of adenine derivatives were identified in silico, and the binding mode of six of the predicted inhibitors was validated by protein crystallography. Two compounds, one for each series, show good ligand efficiency. We propose a route for their further development into potent and selective inhibitors of METTL3.  相似文献   
83.
In the last decades, many reports dealing with technology for the catalytic combustion of methane (CH4) have been published. Recently, attention has increasingly focused on the synthesis and catalytic activity of nickel oxides. In this paper, a NiO/CeO2 catalyst with high catalytic performance in methane combustion was synthesized via a facile impregnation method, and its catalytic activity, stability, and water-resistance during CH4 combustion were investigated. X-ray diffraction, low-temperature N2 adsorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, hydrogen temperature programmed reduction, methane temperature programmed surface reaction, Raman spectroscopy, electron paramagnetic resonance, and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in detail. The incorporation of NiO was found to enhance the concentration of oxygen vacancies, as well as the activity and amount of surface oxygen. As a result, the mobility of bulk oxygen in CeO2 was increased. The presence of CeO2 prevented the aggregation of NiO, enhanced reduction by NiO, and provided more oxygen species for the combustion of CH4. The results of a kinetics study indicated that the reaction order was about 1.07 for CH4 and about 0.10 for O2 over the NiO/CeO2 catalyst.  相似文献   
84.
Microfluidic fluorescence‐activated cell sorters (μFACS) have attracted considerable interest because of their ability to identify and separate cells in inexpensive and biosafe ways. Here a high‐performance μFACS is presented by integrating a standing surface acoustic wave (SSAW)‐based, 3D cell‐focusing unit, an in‐plane fluorescent detection unit, and an SSAW‐based cell‐deflection unit on a single chip. Without using sheath flow or precise flow rate control, the SSAW‐based cell‐focusing technique can focus cells into a single file at a designated position. The tight focusing of cells enables an in‐plane‐integrated optical detection system to accurately distinguish individual cells of interest. In the acoustic‐based cell‐deflection unit, a focused interdigital transducer design is utilized to deflect cells from the focused stream within a minimized area, resulting in a high‐throughput sorting ability. Each unit is experimentally characterized, respectively, and the integrated SSAW‐based FACS is used to sort mammalian cells (HeLa) at different throughputs. A sorting purity of greater than 90% is achieved at a throughput of 2500 events s?1. The SSAW‐based FACS is efficient, fast, biosafe, biocompatible and has a small footprint, making it a competitive alternative to more expensive, bulkier traditional FACS.  相似文献   
85.
Journal of Signal Processing Systems - For vehicles with limited computation resources offloading their computational tasks to a mobile edge computing (MEC) server has been studied in the past as...  相似文献   
86.
正Banq餐厅位是一家新型餐厅,位于便士储蓄银行(Penny Savings Bank)旧大楼以前用来经营银行业务的大厅内。餐厅分成两个部分,前面区域面向华盛顿大街,设计成酒吧,后面的大厅则作为用餐区。然而,这个空间在z轴上以天花板和地面之间的另一个分区为中心进行设计。如果由于餐厅空间活动的多变性而需要保持灵活性——包括两个座位、四个座位和六个座位,以及与聚会和其他活动有关的座位  相似文献   
87.
为了验证屏蔽基准题的准确性,进一步完善我国的标准基准题库,采用蒙特卡罗MCNP程序精细建模计算方法,针对SINBAD屏蔽基准题库,选取其中具有代表性的3例基准题对其准确性进行评估验证。结果表明,模拟计算得到的结果在误差允许的范围内,能够给其他自主软件提供数据验证支持,可将验证结果归入我国屏蔽基准题数据库。   相似文献   
88.
To improve the convertibility of reconfigurable manufacturing system (RMS), the concept of delayed reconfigurable manufacturing system (D-RMS) was proposed. RMS and D-RMS are both constructed around part family. However, D-RMS may suffer from ultra-long system problem with unacceptable idle machines using generic RMS part families. Besides, considering the complex basic system structure of D-RMS, machine selection of D-RMS should be addressed, including dedicated machine, flexible machine, and reconfigurable machine. Therefore, a system design method for D-RMS based on part family grouping and machine selection is proposed. Firstly, a part family grouping method is proposed for D-RMS that groups the parts with more former common operations into the same part family. The concept of longest relative position common operation subsequence (LPCS) is proposed. The similarity coefficient among the parts is calculated based on LPCS. The reciprocal value of the operation position of LPCS is adopted as the characteristic value. The average linkage clustering (ALC) algorithm is used to cluster the parts. Secondly, a machine selection method is proposed to complete the system design of D-RMS, including machine selection rules and the dividing point decision model. Finally, a case study is given to implement and verify the proposed system design method for D-RMS. The results show that the proposed system design method is effective, which can group parts with more former common operations into the same part family and select appropriate machine types.  相似文献   
89.
To solve the special requirements of the high orbit optical remote sensing-satellite for the thermal deformation of the platform, the thermal deformation test and measurement scheme of the satellite platform is designed. Through the comparative analysis of test results, the rationality of the thermal deformation design of the platform structure is verified. The results of thermal deformation measurement show that the maximum deformation of A camera mounting surface is 57.5~〃, and the maximum deformation of B camera mounting surface points to 79.3~〃, which can be used as the basis for thermal deformation prediction of satellite during the orbit operation.  相似文献   
90.
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