全文获取类型
收费全文 | 760849篇 |
免费 | 60481篇 |
国内免费 | 34190篇 |
专业分类
电工技术 | 46405篇 |
技术理论 | 56篇 |
综合类 | 51280篇 |
化学工业 | 119498篇 |
金属工艺 | 43177篇 |
机械仪表 | 48894篇 |
建筑科学 | 58138篇 |
矿业工程 | 23582篇 |
能源动力 | 20387篇 |
轻工业 | 51159篇 |
水利工程 | 15029篇 |
石油天然气 | 45860篇 |
武器工业 | 6332篇 |
无线电 | 84134篇 |
一般工业技术 | 90222篇 |
冶金工业 | 40475篇 |
原子能技术 | 11190篇 |
自动化技术 | 99702篇 |
出版年
2024年 | 3387篇 |
2023年 | 11328篇 |
2022年 | 22313篇 |
2021年 | 30848篇 |
2020年 | 23318篇 |
2019年 | 18467篇 |
2018年 | 21681篇 |
2017年 | 24729篇 |
2016年 | 22359篇 |
2015年 | 29734篇 |
2014年 | 38227篇 |
2013年 | 45621篇 |
2012年 | 49809篇 |
2011年 | 53589篇 |
2010年 | 47165篇 |
2009年 | 44666篇 |
2008年 | 43777篇 |
2007年 | 41223篇 |
2006年 | 40143篇 |
2005年 | 34439篇 |
2004年 | 23703篇 |
2003年 | 20597篇 |
2002年 | 19484篇 |
2001年 | 17476篇 |
2000年 | 16480篇 |
1999年 | 17394篇 |
1998年 | 13989篇 |
1997年 | 11684篇 |
1996年 | 10925篇 |
1995年 | 9061篇 |
1994年 | 7465篇 |
1993年 | 5434篇 |
1992年 | 4605篇 |
1991年 | 3643篇 |
1990年 | 3048篇 |
1989年 | 2605篇 |
1988年 | 2111篇 |
1987年 | 1611篇 |
1986年 | 1409篇 |
1985年 | 1138篇 |
1984年 | 1029篇 |
1983年 | 917篇 |
1982年 | 920篇 |
1981年 | 878篇 |
1980年 | 823篇 |
1979年 | 840篇 |
1978年 | 833篇 |
1977年 | 787篇 |
1976年 | 823篇 |
1973年 | 745篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
V. M. Vorotyntsev G. M. Mochalov M. A. Kolotilova S. S. Suvorov A. V. Koroleva A. Yu. Sharov 《Theoretical Foundations of Chemical Engineering》2008,42(2):197-202
The results of theoretical and experimental studies for the kinetics of separating dichlorosilane from a mixture of volatile chlorosilanes and ultrapurifying the dichlorosilane concentrate by batch distillation are reported. A mathematical model of the process is proposed. It is shown that the model and computational algorithm adequately describe both processes. The obtained experimental and theoretical data made it possible to design a concentration and ultrapurification process with a maximal productivity at a specified product purity. 相似文献
103.
Lei Liu Ying Kong Hong Xu Jin P. Li Jin X. Dong Zhi Lin 《Microporous and mesoporous materials》2008,115(3):624-628
A three-dimensional zinc phosphate compound with DFT topology, designated as ZnPO4-EU1, has been synthesized by an ionothermal approach from the system HF-ZnO–P2O5-choline chloride-imidazolidone. Ethylenediamine, derived from decomposition of the imidazolidone component of the deep-eutectic solvent (DES) itself, is delivered to the synthesis and serves as an appropriate template for ZnPO4-EU1. Experiments in which the synthesis conditions were varied showed that ZnPO4-EU1 may be prepared over a wide molar ratio of P/Zn = 0.55–13.0. Powder X-ray diffraction patterns have been obtained at intervals to track the crystallization process of this material. The experimental data show that Zn3(PO4)2 · 4H2O (a dense phase) was first isolated from the DES after reaction for 1 h. Subsequently, the pure phase of ZnPO4-EU1 was obtained with increasing crystallization time from 12 h to 72 h. The experimental results show that the nucleation and crystallization take place with relatively low levels of solvent degradation, demonstrating that zinc phosphate with a three-dimensional framework can be synthesized by in situ generation of an appropriate template using an unstable DES at high temperatures (150–200 °C). 相似文献
104.
Yu. V. Pokonova 《Solid Fuel Chemistry》2008,42(6):369-372
Impregnants prepared from shale phenols for cellular materials had a cohesive strength of 2.4–18.5 J/m2 and a specific elongation of 160–170%. The adhesive strength toward a metal was 3.5–6.0 J/m2; in the case of concrete, it was greater than the concrete strength. 相似文献
105.
I. I. Nemets Yu. N. Trepalina E. A. Doroganov 《Refractories and Industrial Ceramics》2008,49(3):205-208
Physicotechnical properties are provided for concretes based on mechanically-activated phosphate suspensions previously modified
with magnesium and aluminum hydroxides and silicic acid. The results obtained demonstrate the efficiency of using modifying
additions in order to increase the strength and heat resistance of corundum concretes.
Translated from Novye Ogneupory, No. 5, pp. 32–35, May 2008. 相似文献
106.
对八钢彩涂机组生产中单环氧背面漆的应用进行了分析,介绍了实际生产中使用单环氧背面漆存在的问题,并制定出相应解决措施及方案,确保彩涂单环氧背面漆的表面质量及机械性能的要求. 相似文献
107.
Yu. A. Guloyan 《Glass and Ceramics》2008,65(5-6):177-186
Research on the properties and characteristics of glass that determine the serviceability of the most massive glass objects and glassware is reviewed. The theoretical assumptions, general questions concerning the strength, chemical resistance (corrosion), and spectral characteristics of glass are noted. The properties and characteristics indicated are examined for sheet glass, glass fiber, and glassware. 相似文献
108.
Chun Yang Yin Sharifah Aishah Syed Abdul KadirYing Pei Lim Sharifah Nawirah Syed-AriffinZurinawati Zamzuri 《Fuel Processing Technology》2008
Ash derived from combustion of Malaysian oil palm biomass (empty fruit bunches consisting of fibers) was physically and chemically characterized in order to provide a comprehensive understanding of its specific properties in terms of toxicity, compositions and reusability. Principal analyses conducted include particle size distribution, scanning electron microscopy, elemental dispersive X-ray, elemental analysis, toxicity characteristic leaching procedure (TCLP) as well as thermogravimetric, X-ray diffractometry and Fourier-transform infrared analyses. TCLP result indicated that the oil palm ash (OPA) should not be classified as toxic wastes in terms of heavy metal leachability since leachable copper, cadmium, lead and nickel concentrations were detected below the stipulated leachability limits. It was determined that the OPA contained high amount of potassium as well as presence of silica which implied its suitability to be reused as crude fertilizer or cement replacement material. 相似文献
109.
Yu.V. Butenko P.R. Coxon M. Yeganeh A.C. Brieva K. Liddell V.R. Dhanak L. iller 《Diamond and Related Materials》2008,17(6):962-966
It is generally accepted that diamond is resistant to a wide spectrum of electromagnetic radiation from the ultraviolet through to the soft X-ray range, which makes it very attractive for the fabrication of diamond-based photodetectors. However the effect of photon radiation on the diamond structure has not yet been examined. In the work presented here, photoelectron spectroscopy has been used to study the graphitization of nanodiamond crystallites exposed to extreme ultraviolet radiation. Under such irradiation, the surface hydrogen groups and graphite species are found to prevent graphitization. The mechanism of radiation-induced nanodiamond graphitization is discussed. 相似文献
110.
We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores. 相似文献