全文获取类型
收费全文 | 7781篇 |
免费 | 356篇 |
国内免费 | 49篇 |
专业分类
电工技术 | 216篇 |
综合类 | 20篇 |
化学工业 | 1662篇 |
金属工艺 | 164篇 |
机械仪表 | 193篇 |
建筑科学 | 237篇 |
矿业工程 | 9篇 |
能源动力 | 520篇 |
轻工业 | 766篇 |
水利工程 | 89篇 |
石油天然气 | 156篇 |
武器工业 | 4篇 |
无线电 | 964篇 |
一般工业技术 | 1375篇 |
冶金工业 | 460篇 |
原子能技术 | 77篇 |
自动化技术 | 1274篇 |
出版年
2024年 | 18篇 |
2023年 | 179篇 |
2022年 | 428篇 |
2021年 | 530篇 |
2020年 | 377篇 |
2019年 | 378篇 |
2018年 | 494篇 |
2017年 | 339篇 |
2016年 | 382篇 |
2015年 | 239篇 |
2014年 | 365篇 |
2013年 | 593篇 |
2012年 | 392篇 |
2011年 | 448篇 |
2010年 | 290篇 |
2009年 | 250篇 |
2008年 | 229篇 |
2007年 | 209篇 |
2006年 | 182篇 |
2005年 | 154篇 |
2004年 | 126篇 |
2003年 | 105篇 |
2002年 | 119篇 |
2001年 | 64篇 |
2000年 | 68篇 |
1999年 | 76篇 |
1998年 | 127篇 |
1997年 | 107篇 |
1996年 | 73篇 |
1995年 | 81篇 |
1994年 | 53篇 |
1993年 | 54篇 |
1992年 | 41篇 |
1991年 | 24篇 |
1990年 | 29篇 |
1989年 | 42篇 |
1988年 | 48篇 |
1987年 | 29篇 |
1986年 | 29篇 |
1985年 | 43篇 |
1984年 | 53篇 |
1983年 | 41篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 30篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 22篇 |
1976年 | 30篇 |
1974年 | 17篇 |
排序方式: 共有8186条查询结果,搜索用时 15 毫秒
1.
2.
Adrian Thomas Christopher D. Gilson Tanveer Ahmed 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):73-79
Equipment was developed to measure the time for complete gelling of sodium alginate fibres in calcium chloride solution, taken as the time to achieve maximum tensile strength. The effects of fibre diameter, alginate concentration, alginate composition and calcium chloride concentration on gelling time were investigated. A diffusional model, developed to predict the gelling time, agreed with experimental results except for the effect of calcium ion concentration which was modelled empirically. 相似文献
3.
Handschin E. Hoffmann W. Reyer F. Stephanblome T. Schlucking U. Westermann D. Ahmed S.S. 《Power Systems, IEEE Transactions on》1994,9(1):533-539
The synthesis of the structure of the power system stabiliser (PSS) and its parametrization are based entirely on methods of linear system theory. Thus the desired effect of the PSS is limited to a bounded area around one system operating point. The use of a controller based on fuzzy set theory introduces an event controlled excitation of the synchronous machine taking into account the power system operation. The desired response of the fuzzy controller is given by a set of rules which are obtained from the limits of the voltage regulator and the undesired performance of the conventional excitation control. A fuzzy controller has been developed for which simulation results are provided. These results support the concept of a fuzzy controller for the purpose of excitation control. They show that a well designed fuzzy controller is superior to a fast excitation control with an additional PSS 相似文献
4.
Intercalation of poly[oligo(oxyethylene) methacrylates] onto sodium montmorillonite (MMT) clay has been investigated. A polymer–clay hybrid has been synthesized through intercalation of the monomer followed by its solution free‐radical polymerization. Eight polymer–clay hybrids were prepared using different weight ratios of clay, different oligo(oxyethylene) lengths and different proportions of crosslinker. Evidence of the development of nanostructures is obtained from scanning electron microscopy, and wide‐angle X‐ray diffraction studies support these results which show disappearance of the peak characteristic to d001 spacing. In this hybrid MMT is dispersed homogeneously in the polymer matrix. © 2003 Society of Chemical Industry 相似文献
5.
In this article, a new extension of affine arithmetic is introduced. This technique is based on a quadratic form named general quadratic form. We focus here on the computation of reliable bounds of a function over a hypercube by using this new tool. Some properties
of first quadratic functions and then polynomial ones are reported. In order to show the efficiency of such a method, ten
polynomial global optimization problems are presented and solved by using an interval branch-and-bound based algorithm.
The work of the first author was also supported by the Laboratoire de Mathématiques Appliquées CNRS–FRE 2570, Université de
Pau et des Pays de l'Adour, France, and by the Laboratoire d'Electrotechnique et d'Electronique Industrielle CNRS–UMR5828,
Group EM3, INPT–ENSEEIHT. 相似文献
6.
Silicon - In this study, inorganic-organic hybrid material consisting of tetraethyl orthosilicate (TEOS) and 3-methacryloxypropyl trimethoxysilane (MAPTMS) were prepared with sol-gel process and... 相似文献
7.
A. H. Moinuddin Ahmed Lesley S. Dent Glasser 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1973,23(6):457-463
α-BaO.Al2O3.4H2O has been synthesised and studied by infrared, X-ray and thermal analytical techniques. The compound of approximate formula BaO.Al2O3.0.5H2O, described in Part III, forms as a dehydration product, and appears to be identical with the compound β-BAH2 described by other workers. A possible explanation for the discrepancy in water content is discussed. 相似文献
8.
9.
M. A. Ali M. A. Gafur M. S. Rahman G. M. Ahmed 《Journal of the American Oil Chemists' Society》1985,62(3):520-523
The kernels of 10 different mango varieties were extracted. The physico-chemical characteristics and lipid class composition
of fats were studied. The fat content of mango kernels grown under the soil and climatic conditions of Bangladesh varied from
7.1% to 10%, depending on the variety. The total lipid extracts were fractionated into lipid classes by a combination of column
and thin layer chromatography (TLC). The hydrocarbon and sterol esters varied from 0.3% to 0.7%, triglycerides from 55.6%
to 91.5%, partial glycerides from 2.3% to 4% and free sterol from 0.3% to 0.6%. Free fatty acids amounted to 3.0–37% as oleic;
glycolipids were 0.6–1.2% and phospholipids 0.11–0.8%. The fatty acid composition of triglyceride (TG) fractions was analyzed
by gas liquid chromatography (GLC). Palmitic acid varied from 7.9 molar % to 10.0 molar %, stearic from 38.2% to 40.2%, oleic
from 41.1% to 43.8%, linoleic from 6.0% to 7.6%, linolenic from 0.6% to 1.0% and arachidic acid from 1.7% to 2.6%. TLC revealed
the presence of lyso-phosphatidylcholine, phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and phosphatidic
acid in the phospholipid fraction. 相似文献
10.
The stoichiometric association constants, K, the thermodynamic association constant, KA, and the other thermodynamic parameters such as ΔS°, ΔH° and ΔG° for the association between each of the Ca and Mg ions with benzoate, o-toloate, o-chlorobenzoate and salycylate have been determined at 25°C, 35°C and 45°C in aqueous media. Ion-selective electrode technique has been used in the measurements of Ca and Mg ion activitiesThe trend of association behavior of both Ca and Mg aromatic salts could not be explained on the basis of pKa of the mother organic acids but could be explained based on the trend of Hammet function σ of these salts themselves relative to the corresponding benzoate salt. 相似文献