全文获取类型
收费全文 | 50523篇 |
免费 | 3446篇 |
国内免费 | 2647篇 |
专业分类
电工技术 | 1085篇 |
技术理论 | 2篇 |
综合类 | 4534篇 |
化学工业 | 19863篇 |
金属工艺 | 1557篇 |
机械仪表 | 1479篇 |
建筑科学 | 1675篇 |
矿业工程 | 632篇 |
能源动力 | 1033篇 |
轻工业 | 1695篇 |
水利工程 | 459篇 |
石油天然气 | 2119篇 |
武器工业 | 455篇 |
无线电 | 2702篇 |
一般工业技术 | 6807篇 |
冶金工业 | 1423篇 |
原子能技术 | 240篇 |
自动化技术 | 8856篇 |
出版年
2024年 | 103篇 |
2023年 | 467篇 |
2022年 | 726篇 |
2021年 | 1004篇 |
2020年 | 1043篇 |
2019年 | 1000篇 |
2018年 | 1027篇 |
2017年 | 1244篇 |
2016年 | 1525篇 |
2015年 | 1535篇 |
2014年 | 2739篇 |
2013年 | 2790篇 |
2012年 | 3370篇 |
2011年 | 3755篇 |
2010年 | 2923篇 |
2009年 | 3304篇 |
2008年 | 2998篇 |
2007年 | 3599篇 |
2006年 | 3231篇 |
2005年 | 2958篇 |
2004年 | 2375篇 |
2003年 | 2170篇 |
2002年 | 1900篇 |
2001年 | 1653篇 |
2000年 | 1410篇 |
1999年 | 1134篇 |
1998年 | 911篇 |
1997年 | 660篇 |
1996年 | 560篇 |
1995年 | 479篇 |
1994年 | 426篇 |
1993年 | 337篇 |
1992年 | 258篇 |
1991年 | 191篇 |
1990年 | 178篇 |
1989年 | 135篇 |
1988年 | 104篇 |
1987年 | 60篇 |
1986年 | 39篇 |
1985年 | 35篇 |
1984年 | 36篇 |
1983年 | 25篇 |
1982年 | 24篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 23篇 |
1978年 | 11篇 |
1975年 | 9篇 |
1963年 | 9篇 |
1961年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
111.
水溶性聚偶氮酯的研究 总被引:1,自引:0,他引:1
用Pinner合成方法制备了用PEG400封端的水溶性聚偶氮酯,并表征了其结构;研究了热分解反应动力学及用于乳液聚合的动力学。结果表明,该种引发剂具有引发速度快、热分解机理简单和具有辅助乳化作用等优点。 相似文献
112.
113.
Larry Wos 《Journal of Automated Reasoning》1992,9(3):407-408
This article is the twenty-fourth of a series of articles discussing various open research problems in automated reasoning. The problem proposed for research asks one to find an appropriate theory for modulating across argument and across literal boundaries. Because demodulation has proved so useful—is most cases, even crucial—to automated reasoning, extending this concept to permit canonicalization to be applied at the predicate and at the clause and subclause levels merits exploration. For evaluating a proposed solution to this research problem, we suggest problems from mathematics, logic, program verification, database inquiry, and the world of puzzles.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-31-109-Eng-38. 相似文献
114.
The synthesis and magnetostriction of PrxTb1-x.Fe2, PrxTb1-x Fe2BO2 and PrxTb1-x(Fe0.6Co0.4)2 alloys were investigated in this study. The addition of boron or cobalt atom in PrxTb1-xFe2 could effectively prevent the formation of non-cubic phases, and Pr concentration limit was successfully increased from 0.2 to 0.4. X-ray step scanning for the PrxTb1-xFe2BO2 and PrxTb1-x(Fe0.6Co0.4)2 alloys showed that PrFe2 possessed a large spontaneous magnetostriction λ1111. 相似文献
115.
The synthesis of alternative reaction paths leading to a desired chemical has received increasing attention in the recent past. A procedure to develop new reaction schemes in a systematic manner was reviewed by the authors ( [ 1 -3] ). The algorithm presented in these earlier papers implied the generation of an infinite number of reaction paths. The thermodynamic feasibility is a preliminary screening which reduces the number of chemical production schemes. Further screening is necessary, taking into account considerations which are related to economics, processing, safety and so on. Some constraints related with role specification, gross added value and demand/supply requirements are analysed in this paper. Examples illustrate the application of the screening procedure, showing that the addition of a few constraints results in a dramatic decrease of alternative reaction paths. 相似文献
116.
运用XD工艺制备了颗粒增强TiAl基复合材料。增强颗粒均匀分布于TiAl基体中并细化TiAl合金。通过在TiB_2/TiAl、TiC/TiAl复合材料中加入适量的Si,颗粒增强TiAl基复合材料的室温延性得到了改善。 相似文献
117.
The concept of combinatorial objects is formalized. It allows strict definition of a combinatorial optimization problem (COP).
An efficient metaheuristic method to solve COPs (H-method) is considered. It includes stochastic local search algorithms as
a built-in procedure. A parallel implementation of the H-method is set forth and analyzed. The results from a numerical experiment
and solution of some well-known COPs on personal computers and on the SKIT cluster supercomputer are presented.
The study was supported by INTAS (Project 06-1000017-8909).
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 70–79, November–December 2007. 相似文献
118.
The efficiency characteristics of multicast key distribution schemes based on (v, b, r, λ)-designs are investigated. The stability
and connectivity of such designs are estimated. These estimates generalize and enhance the well-known estimates for the efficiency
characteristics of multicast key distribution schemes based on incomplete block designs.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 100–111, May–June 2007. 相似文献
119.
A pseudohyperbolic problem of optimal control of intratumoral drug distribution is formulated. It takes into account the heterogeneity
of tumor tissues and effects of convection diffusion in a fissured porous medium. A mathematical model constructed and the
corresponding optimal control problem are shown to be correct.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 147–154, November–December 2007. 相似文献
120.