全文获取类型
收费全文 | 1008篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 165篇 |
金属工艺 | 37篇 |
机械仪表 | 26篇 |
建筑科学 | 13篇 |
能源动力 | 38篇 |
轻工业 | 54篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 90篇 |
一般工业技术 | 311篇 |
冶金工业 | 98篇 |
原子能技术 | 12篇 |
自动化技术 | 166篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 21篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 21篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 33篇 |
2013年 | 58篇 |
2012年 | 44篇 |
2011年 | 43篇 |
2010年 | 48篇 |
2009年 | 46篇 |
2008年 | 40篇 |
2007年 | 47篇 |
2006年 | 27篇 |
2005年 | 32篇 |
2004年 | 29篇 |
2003年 | 25篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 40篇 |
1997年 | 23篇 |
1996年 | 25篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1971年 | 6篇 |
排序方式: 共有1030条查询结果,搜索用时 31 毫秒
1.
G. Murali Dhar B. N. Srinivas M. S. Rana Manoj Kumar S. K. Maity 《Catalysis Today》2003,86(1-4):45-60
Support effects form important aspect of hydrodesulfurization (HDS) studies and mixed oxide supports received maximum attention in the last two decades. This review will focus attention on studies on mixed oxide supported Mo and W catalysts. For convenience of discussion, these are divided into Al2O3 containing mixed oxide supports, TiO2 containing mixed oxide supports, ZrO2 containing mixed oxide supports and other mixed oxide supports containing all the rest. TiO2 containing mixed oxides received maximum attention, especially TiO2–Al2O3 supported catalysts. A brief discussion about their prospects for application to ultradeep desulfurization is also included. An overview of the available literature with emphasis on research carried out in our laboratory form the contents of this publication. 相似文献
2.
3.
P. Meenakshi S. E. Noorjahan R. Rajini U. Venkateswarlu C. Rose T. P. Sastry 《Bulletin of Materials Science》2002,25(1):25-29
DriedMusa paradiciaca (banana) stem and veins of the leaves, which were hitherto discarded as a waste, were collected and used as starting material
for the preparation of cellulose and cellulose acetate. This cellulose acetate was mixed with polystyrene to form blend of
cellulose acetate-polystyrene in order to provide enhanced stability and extended utility to the end products. The films of
these composites or their individual partners were made separately and studied for their mechanical properties, chemical modification
and morphological changes. We report here that banana stem is good source of cellulose and that cellulose completely undergoes
modification upon esterification. 相似文献
4.
Dispersion-strengthened Al-8.5% Fe-1.2% V-1.7% Si alloy was produced by inert gas atomization and atomized melt deposition processes. Differential scanning calorimetry was used to estimate the extent of undercooling in the alloy powders as a function of powder size and in the atomized melt-deposited alloy as a function of process parameters. The estimated undercooling was found to be a strong function of powder size and processing conditions and varied from 380–200 °C. Alloy powders of diameter greater than 180 jam did not experience any undercooling during solidification. X-ray diffraction analysis was performed to study the dependence of supersaturation of alloying elements and metastable phase formation on the extent of undercooling. When the undercooled alloy was heated to about 400 dgC, formation of Al12(Fe, V)3Si phase with b c c crystal structure from the supersaturated matrix was observed. 相似文献
5.
6.
New spectrophotometric methods for the assay of some antioxidants have been developed using potassium permanganate and metol (p-N-methyl amino phenol). Metol is oxidised at pH 3.0 with potassium permanganate and coupled with antioxidants to give λmax at 560 nm for propyl gallate and gallic acid and 510nm for butylated hydroxy anisole. The method is simple, sensitive, reproducible and accurate within ±1% and applicable to the assay of antioxidants (gallic acid, propyl gallate and butylated hydroxy anisole) in oils and fats. 相似文献
7.
8.
Modeling of the failure of polymer-matrix composites requires substantial information about the mechanisms of failure at the interface, and load redistribution around fiber breaks in the composite. Current interface experiments involving the use of ‘microcomposites’ of single embedded fibers in a matrix generally do not include all the key geometric features of the real composite; in particular, they do not include the effects of fiber volume fraction and the higher matrix shear resulting from closely neighboring fibers. A new experiment was recently devised to assess some of these effects: it is referred to as the single-fiber pull-out from microbundle (SFPOM) experiment. It consists of a hexagonal arrat of seven fibers in a matrix where the outer six fibers are restrained and the center fiber is pulled out. Recent experimental data from tests with this geometry are analyzed here using three mechanical models of the failure process, and parametric studies of the data are performed to assess the appropriateness of each model. Two of the models, based on fracture energy considerations as applied earlier to single embedded fibers in a matrix and adapted to our geometry, were found to model data from the SFPOM experiments poorly. The third model assumes the existence of three zones near a fiber break, including elastic, plastic and frictional debond zones, and was found to provide reasonable fit to the data under realistic assumptions. 相似文献
9.
Experimental data for the densities, dynamic viscosities, sound speeds, and relative permittivities and for three binary systems of methyl methacrylate (MMA)+di-ethers (ethyl, isopropyl, and butyl) at 298.15 and 308.15 K and at atmospheric pressure are reported. The mixture viscosities are correlated by Grunberg–Nissan, McAllister, and Auslander equations over the complete composition range. The sound speeds for the mixtures are also calculated by using free length and collision factor theories, and Nomoto and Junjie equations. From the measured primary properties, deviation functions such as deviations in viscosities, sound speeds, relative permittivities, molar polarizations, excess isentropic compressibilities, and molar electrical susceptibilities were calculated, and the compositional dependence of each of the functions was expressed with a Redlich–Kister type equation. The variation of the Kirkwood correlation factor was determined over the complete composition range. 相似文献
10.
Structural and electrical properties of brush plated ZnTe films 总被引:1,自引:0,他引:1
Zinc telluride thin films were deposited by the brush plating technique at a potential of −0.90 V (SCE) on conducting glass and titanium substrates at different temperatures in the range 30–90 °C. The films were polycrystalline in nature with peaks corresponding to the cubic phase. Direct band gap of 2.30 eV was observed. XPS studiers indicated the formation of ZnTe. Depth profiling studies indicated a uniform distribution of Zn and Te throughout the entire thickness. EDAX measurements were made on the films and it was found that there was a slight excess of Te. The carrier concentration was found to vary from 1014–1015 cm−3 with increase of substrate temperature. The mobility was found to vary from 5 to 60 cm2 V−1 s−1. 相似文献