全文获取类型
收费全文 | 795369篇 |
免费 | 10026篇 |
国内免费 | 2988篇 |
专业分类
电工技术 | 13566篇 |
综合类 | 3298篇 |
化学工业 | 116810篇 |
金属工艺 | 31970篇 |
机械仪表 | 23751篇 |
建筑科学 | 19370篇 |
矿业工程 | 3936篇 |
能源动力 | 20521篇 |
轻工业 | 64341篇 |
水利工程 | 8511篇 |
石油天然气 | 13906篇 |
武器工业 | 75篇 |
无线电 | 91092篇 |
一般工业技术 | 154687篇 |
冶金工业 | 142677篇 |
原子能技术 | 15786篇 |
自动化技术 | 84086篇 |
出版年
2021年 | 6341篇 |
2020年 | 4611篇 |
2019年 | 5915篇 |
2018年 | 23300篇 |
2017年 | 22162篇 |
2016年 | 19667篇 |
2015年 | 7745篇 |
2014年 | 12222篇 |
2013年 | 32703篇 |
2012年 | 21928篇 |
2011年 | 35062篇 |
2010年 | 28140篇 |
2009年 | 28564篇 |
2008年 | 30185篇 |
2007年 | 30799篇 |
2006年 | 20824篇 |
2005年 | 19957篇 |
2004年 | 19405篇 |
2003年 | 19219篇 |
2002年 | 17771篇 |
2001年 | 17514篇 |
2000年 | 16360篇 |
1999年 | 17215篇 |
1998年 | 44085篇 |
1997年 | 30946篇 |
1996年 | 23717篇 |
1995年 | 17816篇 |
1994年 | 15630篇 |
1993年 | 15424篇 |
1992年 | 11086篇 |
1991年 | 10508篇 |
1990年 | 10221篇 |
1989年 | 9963篇 |
1988年 | 9249篇 |
1987年 | 8312篇 |
1986年 | 8202篇 |
1985年 | 9052篇 |
1984年 | 8481篇 |
1983年 | 7591篇 |
1982年 | 7159篇 |
1981年 | 7244篇 |
1980年 | 6995篇 |
1979年 | 6720篇 |
1978年 | 6622篇 |
1977年 | 7721篇 |
1976年 | 10232篇 |
1975年 | 5653篇 |
1974年 | 5385篇 |
1973年 | 5518篇 |
1972年 | 4527篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
The IBM RISC System/6000, a superscalar microprocessor, is presented. The architecture of this processor has its instruction set specifically designed for a superscalar machine containing three independent units-branch, fixed-point, and floating-point. The design also emphasizes high-performance floating-point operations. The design principles are to offer maximum overlap of the three functional units, avoid dead cycles, and define instructions that can (for the most part) be completed at a rate of one per cycle. The branch cycle, fixed- and floating-point units, cache management, and performance are described. Benchmark results are given 相似文献
992.
The problem of residence-time control by the observer-based output feedback is formulated and solved for the case of linear systems with small additive input noise. Both noiseless and noisy measurements are considered. In the noiseless measurements case, it is shown that the fundamental bounds on the achievable residence time depend on the nonminimum phase zeros of the system. In the noisy measurements case, the achievable residence time is shown to be always bounded, and an estimate of this bound is given. Controller design techniques are presented. The development is based on the asymptotic large deviations theory.
Recommended by T K. Caughey 相似文献
993.
The ability to utilize fully automated flexible manufacturing systems (FMS) or develop reliable computer-integrated manufacturing (CIM) systems will depend on our ability to develop reliable and reusable software for large complex systems on a timely basis. To date, software design has not gone very far beyond the ad hoc trial-and-error stage. Consequently, the development of software is slow, expensive, unreliable, and unmanageable. The purpose of this paper is to provide a scientific basis for designing software. The approach used here is that of axiomatic design, which is based on two design axioms: the Independence Axiom and the Information Axiom. The axiomatic approach is based on the recognition of the following common elements in design: the existence of independent domains (i.e. the consumer domain, the functional domain, the physical domain, and the process domain); the need to map between various domains during the design process; the decomposition of the characteristic vectors (i.e. functional requirements, design parameters, and process variables) in their respective domains; the zig-zagging required between the domains for decomposition; and the need to satisfy the design axioms during the design process. The axiomatic approach discussed in this paper provides decision making tools for software design in addition to systematic means of knowledge and data representation, synthesis and analysis of software, and the construction of the module-junction structure diagram. 相似文献
994.
995.
The effect of bimetallic oxide sintering aids on the colloidal stability of homogeneous (surface-coated) and heterogeneous (mechanically mixed) silicon nitride powder mixtures in aqueous solution was studied by acoustophoretic analysis. While the surface charge generation and colloidal stability of single-phase and oxide-coated silicon nitride powder mixtures may be described according to the site dissociation model of amine and hydroxyl surface groups, the surface charge observed in heterogeneous multiphase powder mixtures is associated with the adsorption of soluble metal ion hydroxocomplexes on the nitride particles. Segregation of the mixtures by heteroflocculation, which causes the formation of agglomerates and microstructural defects upon sintering, may be avoided by generation of a threshold surface potential of equal sign on all powder constituents at a pH where the metal hydroxide dissolution is subcritical. 相似文献
996.
997.
998.
Comments that a critical element in the final report of the American Psychological Association (APA) Task Force on the Victims of Crime and Violence may be lost simply because of the enormity and complexity of the issues involved. The real nature of the victim's emotional experience is often not directly addressed by researchers or service providers in the mental health community. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
999.
A 1.3 ?m laser in a compact disc package is coupled to single-mode fibre using two graded-index lenses in a nearly confocal scheme. An increase in the alignment tolerance at the lens-lens interface by a factor of six suggests the design for a potentially very low-cost connectorised laser package. The coupling efficiency of approx. 6% (?12 dB) is shown to be adequate for local loop applications. 相似文献
1000.