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   4342篇
  免费   217篇
  国内免费   9篇
电工技术   68篇
综合类   3篇
化学工业   1171篇
金属工艺   95篇
机械仪表   71篇
建筑科学   173篇
矿业工程   5篇
能源动力   149篇
轻工业   335篇
水利工程   21篇
石油天然气   13篇
武器工业   1篇
无线电   538篇
一般工业技术   776篇
冶金工业   329篇
原子能技术   29篇
自动化技术   791篇
  2023年   25篇
  2022年   64篇
  2021年   79篇
  2020年   69篇
  2019年   80篇
  2018年   103篇
  2017年   96篇
  2016年   123篇
  2015年   107篇
  2014年   158篇
  2013年   275篇
  2012年   229篇
  2011年   291篇
  2010年   223篇
  2009年   182篇
  2008年   223篇
  2007年   201篇
  2006年   180篇
  2005年   150篇
  2004年   130篇
  2003年   116篇
  2002年   130篇
  2001年   60篇
  2000年   74篇
  1999年   67篇
  1998年   66篇
  1997年   84篇
  1996年   69篇
  1995年   69篇
  1994年   62篇
  1993年   43篇
  1992年   43篇
  1991年   38篇
  1990年   48篇
  1989年   41篇
  1988年   28篇
  1987年   26篇
  1986年   24篇
  1985年   40篇
  1984年   40篇
  1983年   37篇
  1982年   47篇
  1981年   34篇
  1980年   17篇
  1979年   28篇
  1978年   19篇
  1977年   18篇
  1976年   18篇
  1974年   15篇
  1970年   15篇
排序方式: 共有4568条查询结果,搜索用时 15 毫秒
41.
Pulsed Nd:YAG lasers have been developed to achieve high peak power and high pulse repetition rate. These systems are being used as drivers for laser-produced plasmas which efficiently convert the 1064-nm laser output to extreme ultraviolet (EUV) light at 13.5 nm for future microlithography systems. The requirements for laser-produced plasma EUV light sources and their integration in lithography tools for high-volume manufacturing are reviewed to establish the key design issues for high-power lasers and plasma targets. Xenon has been identified as a leading target material to realize the goals of intense EUV emission and clean operation. Recent progress in high-power diode-pumped Nd:YAG lasers and xenon targets for EUV generation is reviewed, showing that laser-produced plasma sources meet the needs for current EUV lithography development tools. Future directions to meet EUV source requirements for high-volume manufacturing tools are discussed.  相似文献   
42.
Methyldichlorosilane (CH3SiHCl2) is compared to methylsilane (CH3SiH3) for vapor phase epitaxy of cubic silicon - carbon (NO :) (Si:C) alloys on Si (001). Parameters of interest are growth rate, percent carbon and crystallinity. Carbon incorporation efficiency and experimental window for epitaxial growth are similar for both precursors. The two precursors differ in Si contribution to the film growth rate.  相似文献   
43.
44.
The authors present the design and the development of integrated microwave filters using suspended substrate microstrip, a technology that provides many advantages. Through quasi-static approximation the propagation structure has been treated using integral equations solved with the method of moments. Thanks to this tool of analysis and to an accurate synthesis method, a series of bandpass filters have been designed and manufactured. The results presented validate the accuracy of our design method.  相似文献   
45.
This paper introduces a new environment for developing distributed systems. It is based on theTurtle uml profile. Analysis and design phases, described in previous papers, have been extended with an additional deployment phase. In this new step,Turtle components are deployed over hardware execution nodes, and nodes are connected together throughout links,Turtle deployment diagrams are given a formal semantics inRt-lotos, therefore following the approach used forTurtle analysis and design diagrams. Moreover, the paper presents a Java code generator which outputs appropriate Java code forTurtle deployment diagrams. This code is automatically deployable on networks because it implements node communication using network protocols such asUdp orRmi. ttool, the turtle toolkit has been extended to support these new diagrams and code generators. The attack of protected data exchanged throughout securedHttp sessions serves as example.  相似文献   
46.
47.
Intensive signal processing applications appear in many application domains such as video processing or detection systems. These applications handle multidimensional data structures (mainly arrays) to deal with the various dimensions of the data (space, time, frequency). A specification language allowing the direct manipulation of these different dimensions with a high level of abstraction is a key to handling the complexity of these applications and to benefit from their massive potential parallelism. The Array-OL specification language is designed to do just that. We introduce here an extension of Array-OL to deal with states or delays by the way of uniform inter-repetition dependences. We show that this specification language is able to express the main patterns of computation of the intensive signal processing domain.  相似文献   
48.
We present RERBEE (robust efficient registration via bifurcations and elongated elements), a novel feature-based registration algorithm able to correct local deformations in high-resolution ultra-wide field-of-view (UWFV) fluorescein angiogram (FA) sequences of the retina. The algorithm is able to cope with peripheral blurring, severe occlusions, presence of retinal pathologies and the change of image content due to the perfusion of the fluorescein dye in time. We have used the computational power of a graphics processor to increase the performance of the most computationally expensive parts of the algorithm by a factor of over × 1300, enabling the algorithm to register a pair of 3900 × 3072 UWFV FA images in 5-10 min instead of the 5-7 h required using only the CPU. We demonstrate accurate results on real data with 267 image pairs from a total of 277 (96.4%) graded as correctly registered by a clinician and 10 (3.6%) graded as correctly registered with minor errors but usable for clinical purposes. Quantitative comparison with state-of-the-art intensity-based and feature-based registration methods using synthetic data is also reported. We also show some potential usage of a correctly aligned sequence for vein/artery discrimination and automatic lesion detection.  相似文献   
49.
To simulate the propagation of an electromagnetic plane wave in an inhomogeneous ground, the finite difference approach can be used. One of the main problems in using this method is imposing the boundary conditions near the ground surface, especially at high frequency. Indeed, for the E polarization, the upper top of the numerical grid must be sufficiently far away from the air-ground interface in order to neglect the field due to the heterogeneities and the discretization of the atmosphere is necessary. For magneto-telluric modeling, improved boundary conditions have already been proposed. This paper deals with a new condition, valid everywhere in air and which can be applied for E and H polarization. Thus even at high frequency, as for radar applications, only one line is added to the grid discretizing the ground.  相似文献   
50.
碳化硅(SiC)器件的新特性和移动应用的功率密度要求给功率器件的封装技术提出了新的挑战。现有功率器件的封装技术主要是在硅基的绝缘栅双极晶体管(Insulated Gate Bipolar Transistor,IGBT)和金属氧化物半导体场效应晶体管(Metal Oxide Semiconductor Field Effect Transistor,MOSFET)等基础上发展起来的,并一直都在演进,但这些渐进改良尚不足以充分发挥SiC器件的性能,因而封装技术需要革命性的进步。在简述现有封装技术及其演进的基础上,主要从功率模块的角度讨论了封装技术的发展方向。同时讨论了功率模块的新型叠层结构以及封装技术的离散化、高温化趋势,并对SiC器件封装技术的发展方向做出了综合评估。  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