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   708213篇
  免费   9286篇
  国内免费   2104篇
电工技术   13166篇
综合类   832篇
化学工业   105182篇
金属工艺   27026篇
机械仪表   20936篇
建筑科学   17190篇
矿业工程   3094篇
能源动力   19062篇
轻工业   61608篇
水利工程   7016篇
石油天然气   12007篇
武器工业   100篇
无线电   83533篇
一般工业技术   135732篇
冶金工业   138160篇
原子能技术   14053篇
自动化技术   60906篇
  2021年   6199篇
  2020年   4546篇
  2019年   5900篇
  2018年   10019篇
  2017年   9881篇
  2016年   10356篇
  2015年   7107篇
  2014年   11835篇
  2013年   32245篇
  2012年   18810篇
  2011年   25957篇
  2010年   20442篇
  2009年   22961篇
  2008年   23847篇
  2007年   23467篇
  2006年   20689篇
  2005年   18961篇
  2004年   18253篇
  2003年   17969篇
  2002年   17071篇
  2001年   17064篇
  2000年   16074篇
  1999年   16885篇
  1998年   42843篇
  1997年   30136篇
  1996年   23206篇
  1995年   17546篇
  1994年   15356篇
  1993年   15057篇
  1992年   11139篇
  1991年   10385篇
  1990年   10129篇
  1989年   9725篇
  1988年   9120篇
  1987年   8111篇
  1986年   7980篇
  1985年   8986篇
  1984年   8433篇
  1983年   7506篇
  1982年   7087篇
  1981年   7234篇
  1980年   6827篇
  1979年   6661篇
  1978年   6330篇
  1977年   7614篇
  1976年   9776篇
  1975年   5609篇
  1974年   5348篇
  1973年   5486篇
  1972年   4429篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
The physical widths of reference features incorporated into electrical linewidth test structures patterned in films of monocrystalline silicon have been determined from Kelvin voltage measurements. The films in which the test structures are patterned are electrically insulated from the bulk-silicon substrate by a layer of silicon dioxide provided by SIMOX (Separation by the IMplantation of OXygen) processing. The motivation is to facilitate the development of linewidth reference materials for critical-dimension (CD) metrology-instrument calibration. The selection of the (110) orientation of the starting silicon and the orientation of the structures' features relative to the crystal lattice enable a lattice-plane-selective etch to generate reference-feature properties of rectangular cross section and atomically planar sidewalls. These properties are highly desirable for CD applications in which feature widths are certified with nanometer-level uncertainty for use by a diverse range of CD instruments. End applications include the development and calibration of new generations of CD instruments directed at controlling processes for manufacturing devices having sub-quarter-micrometer features  相似文献   
103.
Photonic networks based on the optical path concept and wavelength division multiplexing (WDM) technology require unique operation, administration, and maintenance (OAM) functions. In order to realize the required OAM functions, the optical path network must support an effective management information transfer method. The method that superimposes a pilot tone on the optical signal appears very interesting for optical path overhead transfer. The pilot tone transmission capacity is determined by the carrier to noise ratio which depends on the power spectral density of the optical signal. The pilot tone transmission capacity of an optical path network employing WDM technology is elucidated; 4.5 kb/s transmission can be realized when the pilot tone modulation index is set at 3%  相似文献   
104.
105.
106.
We present the design of E-kernel, an embedding kernel on the Victor V256 message-passing partitionable multiprocessor, developed for the support of program mapping and network reconfiguration. E-kernel supports the embedding of a new network topology onto Victor's 2D mesh and also the embedding of a task graph onto the 2D mesh network or the reconfigured network. In the current implementation, the reconfigured network can be a line or an even-size ring, and the task graphs meshes or tori of a variety of dimensions and shapes or graphs with similar topologies. For application programs having these task graph topologies and that are designed according to the communication model of E-kernel, they can be run without any change on partitions connected by the 2D mesh, line, or ring. Further, E-kernel attempts the communication optimization of these programs on the different networks automatically, thus making both the network topology and the communication optimization attempt completely transparent to the application programs. Many of the embeddings used in E-kernel are optimal or asymptotically optimal (with respect to minimum dilation cost). The implementation of E-kernel translated some of the many theoretical results in graph embeddings into practical tools for program mapping and network reconfiguration in a parallel system. E-kernel is functional on Victor V256. Measurements of E-kernel's performance on V256 are also included  相似文献   
107.
108.
109.
Carstensen and Rhodes1 have suggested that when, in stability programs, assays cannot be performed immediately after the protocol-designated storage time, then freezing them until such a time when assays can be performed would be a reasonable manner to retain the protocol schedule. They caution, however, that such a procedure may not be valid for dissolution data. The article to follow deals with real-time data showing that such a process is feasible for Nalidixic Acid tablets (and presumably for other tablets as well), and that, furthermore, the dissolution pattern would seem to be “frozen” as well.  相似文献   
110.
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