全文获取类型
收费全文 | 23297篇 |
免费 | 332篇 |
国内免费 | 122篇 |
专业分类
电工技术 | 508篇 |
综合类 | 64篇 |
化学工业 | 3183篇 |
金属工艺 | 940篇 |
机械仪表 | 660篇 |
建筑科学 | 546篇 |
矿业工程 | 67篇 |
能源动力 | 601篇 |
轻工业 | 1833篇 |
水利工程 | 214篇 |
石油天然气 | 179篇 |
武器工业 | 1篇 |
无线电 | 2605篇 |
一般工业技术 | 4080篇 |
冶金工业 | 6162篇 |
原子能技术 | 420篇 |
自动化技术 | 1688篇 |
出版年
2021年 | 151篇 |
2020年 | 115篇 |
2019年 | 158篇 |
2018年 | 230篇 |
2017年 | 229篇 |
2016年 | 255篇 |
2015年 | 178篇 |
2014年 | 297篇 |
2013年 | 824篇 |
2012年 | 508篇 |
2011年 | 779篇 |
2010年 | 561篇 |
2009年 | 627篇 |
2008年 | 719篇 |
2007年 | 750篇 |
2006年 | 633篇 |
2005年 | 722篇 |
2004年 | 587篇 |
2003年 | 635篇 |
2002年 | 678篇 |
2001年 | 674篇 |
2000年 | 601篇 |
1999年 | 616篇 |
1998年 | 2173篇 |
1997年 | 1407篇 |
1996年 | 1048篇 |
1995年 | 720篇 |
1994年 | 622篇 |
1993年 | 645篇 |
1992年 | 360篇 |
1991年 | 345篇 |
1990年 | 345篇 |
1989年 | 345篇 |
1988年 | 293篇 |
1987年 | 269篇 |
1986年 | 246篇 |
1985年 | 275篇 |
1984年 | 215篇 |
1983年 | 202篇 |
1982年 | 186篇 |
1981年 | 217篇 |
1980年 | 203篇 |
1979年 | 164篇 |
1978年 | 152篇 |
1977年 | 280篇 |
1976年 | 386篇 |
1975年 | 127篇 |
1974年 | 110篇 |
1973年 | 118篇 |
1972年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
31.
U. Schmoch 《Scientometrics》1993,26(1):193-211
The use of references of patent search reports as transfer indications needs a good theoretical understanding of the underlying examination procedures. On this background, different patent indicators based on sample patents and on respective references can be established and combined to a network which gives an interesting insight into the complex process of knowledge transfer from science to technology. 相似文献
32.
33.
34.
Today patients want to change their Christian names not so much for social support but in order to obtain sex change operations. For this reason among others we caution against casual and careless evaluations and plead for conscientiousness and thoroughness. The spectrum of 16 evaluation cases in the year 1995 is presented. Following this and looking for guiding principles, the most important aspects are discussed: the dilatable frame of the written law, the examiner's diagnostic process, the duty of being well informed, reconstruction of development as the first goal of examination, real-life self-testing and therapy, the obligation to report one's own findings, change of Christian name and indication of operation, evaluation for gender changing, problems of the judge-expert relationship and of future development. 相似文献
35.
In this paper, the scattering of electromagnetic waves by a perfectly conducting semi-infinite elliptic cone is treated. The exact solution of this boundary value problem in problem-adapted spheroconal coordinates in the form of a spherical multipole expansion is of poor convergence if both the source point and the field point are far away from the cone's tip. Therefore, an appropriate sequence transformation of these series expansions (we apply the Shanks transformation) is necessary to numerically determine the dyadic diffraction coefficients and bistatic radar cross sections (RCS) for an arbitrary elliptic cone. Our far-field data for an elliptic cone, a circular cone, and a plane angular sector are compared with some other results obtained with the aid of quite different methods 相似文献
36.
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
37.
38.
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
39.
L Rudzik E Wüst F J Laven U Marquardt 《Zeitschrift für Lebensmittel-Untersuchung und -Forschung》1987,185(4):271-274
The theory of deconvolution of infra-red spectra is presented and illustrated using milk protein spectra. The advantage of this method is impressively demonstrated and its relevance for dairy farming shown using a simple example, the cooling of milk. 相似文献
40.