全文获取类型
收费全文 | 80981篇 |
免费 | 5802篇 |
国内免费 | 2792篇 |
专业分类
电工技术 | 3976篇 |
技术理论 | 6篇 |
综合类 | 4439篇 |
化学工业 | 14263篇 |
金属工艺 | 4167篇 |
机械仪表 | 5240篇 |
建筑科学 | 5339篇 |
矿业工程 | 2406篇 |
能源动力 | 2645篇 |
轻工业 | 5448篇 |
水利工程 | 1020篇 |
石油天然气 | 5285篇 |
武器工业 | 461篇 |
无线电 | 8965篇 |
一般工业技术 | 10954篇 |
冶金工业 | 4420篇 |
原子能技术 | 829篇 |
自动化技术 | 9712篇 |
出版年
2024年 | 310篇 |
2023年 | 1363篇 |
2022年 | 2240篇 |
2021年 | 3162篇 |
2020年 | 2395篇 |
2019年 | 2148篇 |
2018年 | 2502篇 |
2017年 | 2733篇 |
2016年 | 2337篇 |
2015年 | 2937篇 |
2014年 | 3808篇 |
2013年 | 4733篇 |
2012年 | 4880篇 |
2011年 | 5426篇 |
2010年 | 4587篇 |
2009年 | 4363篇 |
2008年 | 4292篇 |
2007年 | 4037篇 |
2006年 | 4049篇 |
2005年 | 3678篇 |
2004年 | 2496篇 |
2003年 | 2281篇 |
2002年 | 2050篇 |
2001年 | 1776篇 |
2000年 | 1933篇 |
1999年 | 2176篇 |
1998年 | 1990篇 |
1997年 | 1578篇 |
1996年 | 1539篇 |
1995年 | 1271篇 |
1994年 | 1021篇 |
1993年 | 778篇 |
1992年 | 583篇 |
1991年 | 453篇 |
1990年 | 351篇 |
1989年 | 278篇 |
1988年 | 249篇 |
1987年 | 166篇 |
1986年 | 129篇 |
1985年 | 116篇 |
1984年 | 80篇 |
1983年 | 53篇 |
1982年 | 48篇 |
1981年 | 35篇 |
1980年 | 36篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 18篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
51.
ATM局域网仿真体系结构的研究 总被引:4,自引:0,他引:4
本文在简要叙述了基于ATM技术进行局域网仿真的原理后,对局域网仿真体系结构作了一些探讨。考虑的重点是无连接服务和群播功能的实现 相似文献
52.
53.
本文详细叙述了海上靶场角度量录取糸统的组成、测试原理及其功能设计,简要介绍了该系统在靶扬的应用情况. 相似文献
54.
Analysis of composite laminates with transverse cracks 总被引:1,自引:0,他引:1
The analysis of the behaviour of composite laminates with general balanced lay-up sequences and containing distributed transverse cracks is discussed and demonstrated in this paper. It is shown that a constitutive model of damage for composites, which has been successfully used to analyse the effects of uniformly distributed transverse cracks in cross-ply laminates, can be readily extended to the analysis of uniformly distributed transverse cracks in more general symmetric laminates. The further extension of the theory to non-uniformly distributed damage can be achieved by finite element analysis. It is shown that the finite element implementation of the theory is particularly simple since the contribution of the damage to the overall behaviour can be incorporated into the force vectors. 相似文献
55.
When a heterogeneous elastic material is represented by an effective homogeneous elastic solid, average stress and strain fields are used. The meaning of the J-integral in the effective homogeneous solid is investigated. A periodically layered medium is considered. The relation between the J-integrals in the original layered medium and the effective medium is derived. 相似文献
56.
L. K. Seah
J. Rhodes
B. S. Lim
《Thin》1993,16(1-4):145-177Turning the free edge of an unstiffened flange inwards or outwards to form a ‘lip’, can substantially improve the local buckling resistance of a member. The lip is the most common type of edge stiffener used in cold-rolled, thin-walled sections. In this paper the behaviour of plate elements of thin-walled sections stiffened by compound lips (i.e. lips which are folded twice to form ‘lips on the lips’) is examined both theoretically and experimentally. An outline of a series of tests on compound edge-stiffened thin-walled sections of various geometries is given and some load-end compression displacement paths are compared with the theoretical predictions. Reasonably good agreement is obtained between the experimental and theoretical results. Comparisons of the theoretical predictions with experimental results of other researchers are also presented in this paper. 相似文献
57.
An alternative approach is presented in this article for the calculation of the activity of FeO, Fe2O3, and the other component in ternary oxide slags when the redox behavior of iron oxides is known. The approach avoids the
use of the “tangent intercepts” to the iso-oxygen activity curves as required in Schuhmann's method. Favorable comparisons
were obtained for the systems of FeO-Fe2O3-CaO and FeO-Fe2O3-SiO2 between the isoactivity curves derived using this method and those established in previous work using Schuhmann's method.
Direct calculation of the free energy of mixing from the redox data is also possible. An example is given for the FeO-Fe2O2-CaO system. 相似文献
58.
Kwang Soo Lee In Soo Park & Dong Sun Lee 《International Journal of Food Science & Technology》1996,31(1):7-13
The aim of this study was to design a modified atmosphere package for a mixed vegetable salad consisting of 75 g of cut carrot, 55 g of cut cucumber, 20 g of sliced garlic and 50 g of whole green pepper. Respiration data of all the components were combined with film permeability data to predict package atmospheres and design optimal packages for experimental testing for improved shelf-life of the produce. The optimal package avoided minimum O2 and maximum CO2 tolerance limits, and chilling injury temperatures for any component. A pouch form package made of 27 mm low density polyethylene developed a modified atmosphere of 2.0–2.1% O2 and 5.5–5.7% CO2 , which was beneficial for all components and provided better quality retention than other test packages. 相似文献
59.
60.
机械化栽培甜菜平均单产33.18吨/公顷,比人工栽培生产田提高52.03%;平均含糖15.5度,比人工栽培生产田提高1.09度;平均技术效果138.2元/公顷;经济效果1588.8元/公顷;创造社会经济效益24.47万元。 相似文献