全文获取类型
收费全文 | 258091篇 |
免费 | 3357篇 |
国内免费 | 1108篇 |
专业分类
电工技术 | 4026篇 |
综合类 | 2409篇 |
化学工业 | 38697篇 |
金属工艺 | 12429篇 |
机械仪表 | 8098篇 |
建筑科学 | 6539篇 |
矿业工程 | 1423篇 |
能源动力 | 5762篇 |
轻工业 | 19772篇 |
水利工程 | 2943篇 |
石油天然气 | 3465篇 |
武器工业 | 2篇 |
无线电 | 28907篇 |
一般工业技术 | 49117篇 |
冶金工业 | 35681篇 |
原子能技术 | 4533篇 |
自动化技术 | 38753篇 |
出版年
2021年 | 1302篇 |
2019年 | 1249篇 |
2018年 | 16303篇 |
2017年 | 15220篇 |
2016年 | 11981篇 |
2015年 | 2146篇 |
2014年 | 2928篇 |
2013年 | 7949篇 |
2012年 | 7608篇 |
2011年 | 15558篇 |
2010年 | 13141篇 |
2009年 | 11301篇 |
2008年 | 12507篇 |
2007年 | 13438篇 |
2006年 | 5114篇 |
2005年 | 5840篇 |
2004年 | 5565篇 |
2003年 | 5280篇 |
2002年 | 4630篇 |
2001年 | 4217篇 |
2000年 | 4092篇 |
1999年 | 4107篇 |
1998年 | 10428篇 |
1997年 | 7415篇 |
1996年 | 5696篇 |
1995年 | 4289篇 |
1994年 | 3628篇 |
1993年 | 3572篇 |
1992年 | 2615篇 |
1991年 | 2559篇 |
1990年 | 2416篇 |
1989年 | 2434篇 |
1988年 | 2385篇 |
1987年 | 2126篇 |
1986年 | 2066篇 |
1985年 | 2368篇 |
1984年 | 2185篇 |
1983年 | 2012篇 |
1982年 | 1880篇 |
1981年 | 1944篇 |
1980年 | 1796篇 |
1979年 | 1816篇 |
1978年 | 1776篇 |
1977年 | 2109篇 |
1976年 | 2674篇 |
1975年 | 1542篇 |
1974年 | 1535篇 |
1973年 | 1591篇 |
1972年 | 1338篇 |
1971年 | 1245篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
D. Solís-Cortés E. Navarrete-Astorga J.L. Costa-Krämer J. Salguero-Fernandez R. Schrebler D. Leinen E.A. Dalchiele J.R. Ramos-Barrado F. Martín 《Ceramics International》2019,45(5):5577-5587
C-axis textured thin films of gallium-doped indium zinc oxide (GIZO) with a 2% ratio of Ga/Zn, were obtained via RF-magnetron sputtering with high transparency and electrical conductivity. A Box-Behnken response surface design was used to evaluate the effects of the deposition parameters (In2O3 target power, deposition time, and substrate temperature) on the chemical composition, optical, electrical, and structural properties of the GIZO films. The optical constants and the electrical properties were obtained using optical models. The GIZO stoichiometry, and therefore the In/Zn atomic ratio, affected the crystallinity, crystalline parameters, band gap, and charge carrier mobility of the GIZO films. The charge carrier density was related to the change in the crystalline parameters of the hexagonal structure and the In/Zn atomic ratio. The best electrical conductivity values (1.75?×?103 Ω?1 cm?1) were obtained for GIZO films with In/Zn ratio ≥?1. Several figures of merit (FOM) defined for the visible and solar regions were comparatively used to select the optimal In/Zn atomic ratio that provided the best balance between the conductivity and the transparency. The optimal In/Zn ratio was in a range of 0.85–0.90 for the GIZO films. 相似文献
52.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
53.
D. M. Mukhammadiev F. Kh. Ibragimov T. D. Mukhammadiev 《Journal of Machinery Manufacture and Reliability》2020,49(3):256-262
The dynamic characteristics of a saw gin as a subsystem with lumped and distributed parameters are considered in the paper. On the basis of investigation of the machine assembly, graphs are drawn that allow establishing the maximum values of the angle of relative rotation and the angle of rotation of the saw cylinder shaft under torsion. 相似文献
54.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
55.
56.
57.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献
58.
59.
60.