全文获取类型
收费全文 | 179365篇 |
免费 | 15659篇 |
国内免费 | 8435篇 |
专业分类
电工技术 | 11395篇 |
技术理论 | 13篇 |
综合类 | 11656篇 |
化学工业 | 29327篇 |
金属工艺 | 9917篇 |
机械仪表 | 11261篇 |
建筑科学 | 13723篇 |
矿业工程 | 5444篇 |
能源动力 | 5301篇 |
轻工业 | 12446篇 |
水利工程 | 3271篇 |
石油天然气 | 10722篇 |
武器工业 | 1411篇 |
无线电 | 21537篇 |
一般工业技术 | 21509篇 |
冶金工业 | 8746篇 |
原子能技术 | 1923篇 |
自动化技术 | 23857篇 |
出版年
2024年 | 900篇 |
2023年 | 3415篇 |
2022年 | 6341篇 |
2021年 | 8499篇 |
2020年 | 6401篇 |
2019年 | 5058篇 |
2018年 | 5724篇 |
2017年 | 6397篇 |
2016年 | 5704篇 |
2015年 | 7589篇 |
2014年 | 9399篇 |
2013年 | 11264篇 |
2012年 | 12264篇 |
2011年 | 12882篇 |
2010年 | 11000篇 |
2009年 | 10395篇 |
2008年 | 9917篇 |
2007年 | 9130篇 |
2006年 | 9310篇 |
2005年 | 7968篇 |
2004年 | 5312篇 |
2003年 | 4473篇 |
2002年 | 4002篇 |
2001年 | 3603篇 |
2000年 | 3534篇 |
1999年 | 4147篇 |
1998年 | 3453篇 |
1997年 | 2932篇 |
1996年 | 2741篇 |
1995年 | 2213篇 |
1994年 | 1798篇 |
1993年 | 1297篇 |
1992年 | 1044篇 |
1991年 | 785篇 |
1990年 | 567篇 |
1989年 | 465篇 |
1988年 | 367篇 |
1987年 | 252篇 |
1986年 | 209篇 |
1985年 | 129篇 |
1984年 | 116篇 |
1983年 | 86篇 |
1982年 | 86篇 |
1981年 | 68篇 |
1980年 | 62篇 |
1979年 | 29篇 |
1978年 | 25篇 |
1977年 | 24篇 |
1976年 | 26篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
71.
72.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
73.
通过对抽样检验方法的研究,确立了区间估计的下限公式,用来在已知样本值的情况下确定导弹单发命中概率出现在该区间内的置信水平和精确度。 相似文献
74.
Ferrite is a potential sorbent for flue gases such as CO2, H2S and SO2. This paper discusses the adsorption and decomposition of CO2 into carbon by hydrogen-activated waste ferrites prepared from Berkeley Pit acid mine water (Butte, MT). The decomposition effectiveness of these waste ferrites was studied at 300 °C and compared with the synthetic magnetite obtained from ferrous sulfate solution in our laboratory. The decomposition was measured by two methods: indirectly by measuring the adsorption rate of CO2 and directly by analysing the carbon deposited on the samples. The results indicated that the mixed waste ferrite had good affinity for the adsorption and decomposition. The CO2 decomposition data of both sorbents fitted the first-order reaction kinetics. Even though the surface area of the magnetite was higher than that of waste ferrite, the CO2 decomposition rate of the waste ferrite was estimated to be 2.5 times higher than that of magnetite under identical conditions. The carbon analysis deposited on the sample indicated that the CO2 was 100% decomposed into carbon and other carbon/hydrogen compounds by the waste ferrite, whereas the conversion was 43% by the magnetite. In terms of specific adsorption of carbon, ferrite was three to five times more efficient than magnetite. 相似文献
75.
76.
77.
The use of the analytically decoupled near-tip displacement solutions as an alternative approach, is presented in this paper for the efficient finite element evaluation of the decoupled weight functions for an orthotropic 2-D crack. This alternative approach has been validated by directly comparing the prior weight function results with a symmetric mesh approach in the crack-tip neighborhood, and indirectly by comparing the calculated stress intensity factors (KI(II)) values using the computed weight functions with available KI(II) solutions of the 2-D mixed mode orthotropic cracks. In addition, this approach with analytically decoupled near-tip displacement solutions for calculating weight functions at all locations, can facilitate further extension of weight function evaluations to a more general 2-D anisotropic crack. 相似文献
78.
通过对不同配方、工艺下的LaCrMnNiO系热敏陶瓷的微观结构研究,指出材料的相组成对其宏观电性能的影响,并提出了通过复合工艺利用“过渡相”的形成,对材料的“最终相”加以控制的方法。文中列出了使用XRD及XPS手段对材料微观结构的分析结果及有关电性能的测试数据。 相似文献
79.
80.
Motoharu Fujigaki In Hong Yang Yoshiharu Morimoto Eung Kyo Han 《NDT & E International》1996,29(4):197-203
There is no good method to measure the shape and the strain distributions of a structure changing with time. We have previously proposed the Fourier transform grid method (FTGM) to measure the three-dimensional shape and surface strain distributions of stationary objects by analysing the two-dimensional grating images recorded with two cameras. In the stereoscopic method, it is very important to determine the accurate geometric parameters of the camera system. In this paper, the positions and the directions of cameras are accurately determined using the FTGM applied to images of a reference object on which a two-dimensional grating is drawn. Applications for analysing shape and strain distributions of vibrating rubber plates and a moving human skin are shown. 相似文献