全文获取类型
收费全文 | 201399篇 |
免费 | 2331篇 |
国内免费 | 616篇 |
专业分类
电工技术 | 3482篇 |
综合类 | 149篇 |
化学工业 | 29227篇 |
金属工艺 | 8091篇 |
机械仪表 | 6121篇 |
建筑科学 | 4865篇 |
矿业工程 | 1308篇 |
能源动力 | 5178篇 |
轻工业 | 17219篇 |
水利工程 | 2302篇 |
石油天然气 | 4054篇 |
武器工业 | 8篇 |
无线电 | 23227篇 |
一般工业技术 | 40275篇 |
冶金工业 | 37744篇 |
原子能技术 | 5099篇 |
自动化技术 | 15997篇 |
出版年
2021年 | 1619篇 |
2019年 | 1584篇 |
2018年 | 2582篇 |
2017年 | 2662篇 |
2016年 | 2795篇 |
2015年 | 1806篇 |
2014年 | 3098篇 |
2013年 | 9036篇 |
2012年 | 5080篇 |
2011年 | 7082篇 |
2010年 | 5630篇 |
2009年 | 6390篇 |
2008年 | 6485篇 |
2007年 | 6556篇 |
2006年 | 5628篇 |
2005年 | 5278篇 |
2004年 | 5046篇 |
2003年 | 4929篇 |
2002年 | 4555篇 |
2001年 | 4691篇 |
2000年 | 4615篇 |
1999年 | 4762篇 |
1998年 | 11523篇 |
1997年 | 8223篇 |
1996年 | 6476篇 |
1995年 | 4723篇 |
1994年 | 4326篇 |
1993年 | 4134篇 |
1992年 | 3249篇 |
1991年 | 3096篇 |
1990年 | 2894篇 |
1989年 | 2982篇 |
1988年 | 2841篇 |
1987年 | 2428篇 |
1986年 | 2325篇 |
1985年 | 2737篇 |
1984年 | 2519篇 |
1983年 | 2373篇 |
1982年 | 2118篇 |
1981年 | 2221篇 |
1980年 | 2044篇 |
1979年 | 2137篇 |
1978年 | 2132篇 |
1977年 | 2393篇 |
1976年 | 3213篇 |
1975年 | 1844篇 |
1974年 | 1773篇 |
1973年 | 1784篇 |
1972年 | 1455篇 |
1971年 | 1346篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
This paper is devoted to presenting controllability and stabilizability issues associated to a class of nonsmooth dynamical systems, namely complementarity dynamical systems. The main existing results are summarized, and some possible research directions are provided. Convex analysis and complementarity problems are claimed to be the main analysis tools for control related studies. This paper mainly focuses on mechanical applications. 相似文献
202.
M.Y. Shen Z.B. ZhangX.L. Niu 《Computer Methods in Applied Mechanics and Engineering》2003,192(25):2703-2725
The generalized compact (GC) schemes and some of their important properties are presented. And a new way for constructing high order accuracy and high-resolution GC schemes is presented. The schemes constructed by using this way could satisfy some principles and demands prescribed in advance to ensure some desired properties to the schemes, such as the principle about suppression of the oscillations, the principle of stability, the order of accuracy and number of scheme points, etc. As two examples, a three-point third-order compact scheme and a three-point fifth-order GC scheme satisfying the principle about suppression of the oscillations and the principle of stability are described in this paper. Numerical results show that these schemes are shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics. Fourier analysis shows that the resolution characteristics are spectral-like. 相似文献
203.
204.
205.
The quantities of olefins, polyaromatic hydrocarbons and char formed during thermal decomposition in closed systems of alkylbenzenes are substantially reduced if the decomposition takes place in the presence of a good acceptor molecule such as pyrene or adamantane. The chemistry seems to be applicable to the upgrading of whole crude oils by a thermal treatment at 425-450°C in a closed system for 20-25 minutes. 相似文献
206.
207.
The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described 相似文献
208.
P. C. Campbell E. B. Hawbolt J. K. Brimacombe 《Metallurgical and Materials Transactions A》1991,22(11):2769-2778
The goal of this study was to develop a mathematical model which incorporates heat flow, phase transformation kinetics, and
property-structure-composition relationships to predict the mechanical properties of steel rod being control cooled under
industrial conditions. Thus, the principles of microstructural engineering have been brought to bear on this interdisciplinary
problem by combining computer modeling with laboratory measurements of heat flow, austenite decomposition kinetics, microstructure
and mechanical properties, and industrial trials to determine heat transfer and obtain rod samples under known conditions.
Owing to the length and diversity of the study, it is reported in three parts,[8191]the first of which is concerned with the heat flow measurements. A relatively simple and reliable technique, involving a preheated
steel rod instrumented with a thermocouple secured at its centerline, has been devised to determine the cooling rate in different
regions of the moving bed of rod loops on an operating Stelmor line. The measured thermal response of the rod has been analyzed
by two transient conduction models (lumped and distributed parameter, respectively) to yield overall heat-transfer coefficients
for radiation and convection. The adequacy of the technique has been checked by cooling instrumented rods under well-defined,
air crossflow conditions in the laboratory and comparing measured heat-transfer coefficients to values predicted from well-established
equations. The industrial thermal measurements have permitted the characterization of a coefficient to account for radiative
interaction among adjacent rod loops near the edge and at the center of the bed.
Formerly Graduate Student, The University of British Columbia. 相似文献
209.
210.