全文获取类型
收费全文 | 53903篇 |
免费 | 6249篇 |
国内免费 | 4042篇 |
专业分类
电工技术 | 3237篇 |
综合类 | 5015篇 |
化学工业 | 8991篇 |
金属工艺 | 2821篇 |
机械仪表 | 3162篇 |
建筑科学 | 5734篇 |
矿业工程 | 2448篇 |
能源动力 | 2132篇 |
轻工业 | 3368篇 |
水利工程 | 1868篇 |
石油天然气 | 2841篇 |
武器工业 | 658篇 |
无线电 | 7154篇 |
一般工业技术 | 8175篇 |
冶金工业 | 2443篇 |
原子能技术 | 1118篇 |
自动化技术 | 3029篇 |
出版年
2024年 | 348篇 |
2023年 | 1030篇 |
2022年 | 1698篇 |
2021年 | 2017篇 |
2020年 | 2132篇 |
2019年 | 1901篇 |
2018年 | 1703篇 |
2017年 | 2141篇 |
2016年 | 2097篇 |
2015年 | 2244篇 |
2014年 | 3130篇 |
2013年 | 3345篇 |
2012年 | 3805篇 |
2011年 | 4048篇 |
2010年 | 3021篇 |
2009年 | 3096篇 |
2008年 | 2875篇 |
2007年 | 3443篇 |
2006年 | 3146篇 |
2005年 | 2602篇 |
2004年 | 2243篇 |
2003年 | 1935篇 |
2002年 | 1708篇 |
2001年 | 1334篇 |
2000年 | 1223篇 |
1999年 | 992篇 |
1998年 | 793篇 |
1997年 | 731篇 |
1996年 | 619篇 |
1995年 | 533篇 |
1994年 | 461篇 |
1993年 | 372篇 |
1992年 | 300篇 |
1991年 | 243篇 |
1990年 | 208篇 |
1989年 | 169篇 |
1988年 | 126篇 |
1987年 | 73篇 |
1986年 | 45篇 |
1985年 | 34篇 |
1984年 | 42篇 |
1983年 | 25篇 |
1982年 | 25篇 |
1981年 | 12篇 |
1980年 | 22篇 |
1979年 | 28篇 |
1965年 | 6篇 |
1963年 | 5篇 |
1959年 | 11篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Qingzhao Yao Yuming Zhou Yanqing Sun Xiaoyun Ye 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(4):477-484
TiO2 hybrid molecular imprinted polymer (MIP) for ethofumesate using methacrylic acid (MAA) as the functional monomer and silane
coupling agent 3-(trimethoxysilyl) propylmethacrylate (KH570) as organic–inorganic connective bridge was synthesized via photo-excitation
method. Hydrogen bond was proved to act between MAA and ethofumesate for pre- and post-polymerization binding properties as
testified by UV spectrometric method. KH570 modified TiO2 nanoparticles were prepared via sonochemical reaction, which can accelerate hydrolysis, increase collision chance for the
reactive system and improve the dispersion of the nanoparticles. Scanning electron microscope (SEM), transmission electron
microscope (TEM), binding and the adsorption kinetics experiments as well as thermogravimetric analysis (TGA) were employed
for characterization. The results indicated that the hybrid MIP revealed a larger surface area and more ordered imprinting
cavities with improved thermal stability compared to organic-only MIP. Furthermore, faster adsorption kinetics and enhancive
adsorption capacity were achieved, which made it promising in chemical sensor applications. 相似文献
102.
Jiang Minhong Gu Zhengfei Cheng Gang 《中国稀土学报(英文版)》2005,23(6):723-723
Polymer matrix RE-Fe giant magnetostrictire composite (GMPC) was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC. 相似文献
103.
本文详细分析了解吸塔换热器结堵的原因和对环保装置正常运行的影响,并针对性地提出了防范和处理措施。 相似文献
104.
A. Benhamida I. Djeran-Maigre H. Dumontet S. Smaoui 《International Journal of Rock Mechanics and Mining Sciences》2005,42(7-8):996-1005
The modelling of hydromechanical behavior of clayey sediments by homogenization theory is described. The rheological model of clays buried in depth requires a three-dimensional approach and laboratory experiments to quantify the model parameters. An iterative process which can be coupled to any homogenization method is used to model the porous media behavior. Hydromechanical compaction results from oedometric experiments are simulated with the proposed model. 相似文献
105.
The effects of NOx on the performance of proton exchange membrane (PEM) fuel cell were investigated through the introduction of a mixture containing NO and NO2, in a ratio of 9:1, into the cathode stream of a single PEM fuel cell. The NOx concentrations used in the experiments were 1480 ppm, 140 ppm and 10 ppm, which cover a range of three orders. The experimental results obtained from the tests of durability, polarization, reversibility and electrochemical impedance spectroscopy (EIS) showed a detrimental effect of NOx on the cell performance. The electrochemical measurements results suggested that the impacts of NOx are mainly resulted from the superposition of the oxygen reduction reaction (ORR), NO and HNO2 oxidation reactions, and the increased cathodic impedance. Complete recovery of the cell performance was reached after operating the cell with clean air and then purging with N2 for hours. 相似文献
106.
使用液力偶合器因故障频繁,对高炉稳产、高产造成严重威胁,而且维修费用较高,对偶合器改造后,应用金属迭片挠性联轴器其故障率、维修费用都很低。 相似文献
107.
Halo effects in rating specific pieces of work, as in educational grading, have received little attention. Grades awarded by 2 independent graders to undergraduate projects were analyzed with a correlated uniqueness model. Grades showed substantial halo despite being awarded by expert assessors at the time of reading the work. There was greater halo between different grades applying to the same section of the project than between grades applying to different sections. Supervisors who had regular contact with the student whose work they were grading showed no more halo than other graders. More reliable graders showed less within-section halo than graders of lower reliability but equal between-sections halo. The halo effects observed cannot be entirely attributable to a unitary general impression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
108.
介绍了研制出其性能达国际先进公司同类产品水平的塑封双列直插式光耦合器的工作原理和提高绝缘耐压的技术难点,从引线框架设计、加工精度控制、内包封材料选型、理想内包封形状控制、塑封气密性的实现、环境条件的完善等方面讨论了提高绝缘耐压的设计和工艺要点。 相似文献
109.
动态多目标决策问题的灰色分析方法 总被引:2,自引:0,他引:2
将用于固定时间截面下静态多目标决策的灰色关联理论推广到动态情形,引入局部理想最优效果和整体理想最优效果的概念,提出一种新型的动态多目标决策问题的灰色关联模型,并通过算例说明该方法的合理可行性。 相似文献
110.
The fracture toughness of brittle thermoset resins could be improved significantly by perfectly bonded tough, short fibers through both crack trapping and bridging effects. In this paper, the crack trapping effect was studied through the analysis of the change of strain energy associated with the crack propagation across a regular array of fibers, and the bridging effect was discussed based on the Andersson–Bergkvist model. The fracture resistance increases with the fiber volume fraction, and is independent of the elastic properties of the matrix, the crack length, and the cross-sectional diameter of the fibers. 相似文献