全文获取类型
收费全文 | 310766篇 |
免费 | 34872篇 |
国内免费 | 23647篇 |
专业分类
电工技术 | 25660篇 |
技术理论 | 15篇 |
综合类 | 35572篇 |
化学工业 | 28408篇 |
金属工艺 | 11475篇 |
机械仪表 | 25567篇 |
建筑科学 | 32363篇 |
矿业工程 | 11081篇 |
能源动力 | 13720篇 |
轻工业 | 17767篇 |
水利工程 | 15551篇 |
石油天然气 | 15208篇 |
武器工业 | 3957篇 |
无线电 | 21508篇 |
一般工业技术 | 28580篇 |
冶金工业 | 11713篇 |
原子能技术 | 3771篇 |
自动化技术 | 67369篇 |
出版年
2024年 | 1457篇 |
2023年 | 4215篇 |
2022年 | 8320篇 |
2021年 | 9677篇 |
2020年 | 10348篇 |
2019年 | 8838篇 |
2018年 | 8596篇 |
2017年 | 10566篇 |
2016年 | 12440篇 |
2015年 | 13105篇 |
2014年 | 19547篇 |
2013年 | 20107篇 |
2012年 | 22908篇 |
2011年 | 25070篇 |
2010年 | 18819篇 |
2009年 | 19344篇 |
2008年 | 18776篇 |
2007年 | 21810篇 |
2006年 | 18986篇 |
2005年 | 16246篇 |
2004年 | 13457篇 |
2003年 | 11633篇 |
2002年 | 9238篇 |
2001年 | 7644篇 |
2000年 | 6586篇 |
1999年 | 5270篇 |
1998年 | 4462篇 |
1997年 | 3751篇 |
1996年 | 3269篇 |
1995年 | 2767篇 |
1994年 | 2360篇 |
1993年 | 1717篇 |
1992年 | 1522篇 |
1991年 | 1170篇 |
1990年 | 958篇 |
1989年 | 802篇 |
1988年 | 620篇 |
1987年 | 412篇 |
1986年 | 341篇 |
1985年 | 317篇 |
1984年 | 355篇 |
1983年 | 291篇 |
1982年 | 260篇 |
1981年 | 129篇 |
1980年 | 143篇 |
1979年 | 113篇 |
1978年 | 69篇 |
1977年 | 55篇 |
1976年 | 50篇 |
1959年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
V. P. Naumenko 《Strength of Materials》1996,28(1):10-18
The adoption of unified fracture mechanics terminology (UFMT) will promote efficient communication between specialists in different fields of fracture research, harmonization of national and international standards relating to fracture mechanics, and last but not least improvement of the existing methodology for teaching and education in fatigue and fracture. In this paper the definitions of some basic and related terms included in different standards on fracture mechanics terminology are confronted with one another. Alternative definitions of the same terms are offered. By this strategy the author tries to show that the definitions of basic and related terms appropriate for the UFMT should emerge as a consequence of harmonizing a crack model with an actual crack and then both taken together with a fracture model, laboratory test methods, and failure assessment codes.Published in Problemy Prochonsti, No. 1, pp. 17–29, January, 1996.This paper is published as a matter of discussion. 相似文献
72.
段群章 《有色金属材料与工程》1993,(1)
本文评述了近年来苯基荧光酮类试剂在金属及合金光度分析中应用的发展状况,显色反应的条件,以及相应光度分析方法的检测限和测定范围等。参考文献87篇。 相似文献
73.
本文介绍了一种实用的数据库设计方法,它以实体分析法为理论基础,通过对我们日常使用的表进行聚集和归类,完成数据库的逻辑设计,所设计的数据库满足BNOF范式。同时该方法可操作性较强,本文还介绍了自行设计的ERCM数据库辅助设计工具。 相似文献
74.
75.
Li2O在保护渣中的作用 总被引:7,自引:0,他引:7
采用在不同玻璃性的两种基渣中加入Li2O为研究Li2O对保护渣粘度,熔化温度及玻璃性能的影响,并对Li2O改善保护渣玻璃性的机理进行了探讨,提出了寻找高速连铸保护渣中Li2O的代用物的一种方法。 相似文献
76.
A general numerical model is described for the dissolution kinetics of spherical particles in binary systems for any combination of first order reactions at the particle-matrix interface and long distance diffusion within the matrix. The model is applicable to both finite and infinite media and handles both complete and partial particle dissolution. It is shown that interfacial reactions can have a strong effect on the dissolution kinetics, the solute concentration at the particle-matrix interface and the solute concentration profile in the matrix. 相似文献
77.
Neil Kirkpatrick 《Packaging Technology and Science》1993,6(3):159-172
Solid-waste management, and in particular the disposal of used packaging, is currently the subject of much topical debate. This is driven by both consumer and legislative pressures. Consumers see used packaging as a highly visible element of municipal solid waste, complaining of excessive packaging and low levels of recycling. Legislators, perhaps in pandering to the views expressed by consumer bodies, have been active within the CEC and individual Member States by introducing (or proposing) legislation or similar regulatory tools and targets to facilitate a greater diversion of used packaging from disposal by landfill to alternative solid-waste management practices, in particular recycling, which are widely accepted to have a lower impact on the environment. In this paper the relative environmental profiles of pursuing alternative solid-waste management practices to disposal by landfill are explored, focusing not just on solid waste per se but also on associated considerations of energy consumption and emissions, which are invariably overlooked as factors contributing to the environmental impact of solid-waste management practices. 相似文献
78.
Results from applying the model on a sample of contractors, the majority of whom were international and operating in Egypt, reinforces the credibility of the developed methodology, claim the authors. 相似文献
79.
The general mixed μ problem has been shown to be NP hard, so that the exact solution of the general problem is computationally intractable, except for small problems. In this paper we consider not the general problem, but a particular special case of this problem, the rank one mixed μ problem. We show that for this case the mixed μ problem is equivalent to its upper bound (which is convex), and it can in fact be computed easily (and exactly). This special case is shown to be equivalent to the so-called ‘affine parameter variation’ problem (for a polynomial with perturbed coefficients) which has been examined in detail in the literature, and for which several celebrated ‘Kharitonov-type’ results have been proven. 相似文献
80.
根据转炉炼钢的物理化学反应机理,从质量平衡和能量平衡的计算出发,通过小参数变动,导出了增量式静态模型中矿石方程和供氧方程的系数。所得结论与新日铁资料基本相符。同时,还进行了炉料和产物的计算,分析了改变废钢比对生产的影响。 相似文献