全文获取类型
收费全文 | 31707篇 |
免费 | 1551篇 |
国内免费 | 143篇 |
专业分类
电工技术 | 492篇 |
综合类 | 246篇 |
化学工业 | 5488篇 |
金属工艺 | 838篇 |
机械仪表 | 718篇 |
建筑科学 | 998篇 |
矿业工程 | 170篇 |
能源动力 | 517篇 |
轻工业 | 4371篇 |
水利工程 | 218篇 |
石油天然气 | 148篇 |
武器工业 | 10篇 |
无线电 | 1690篇 |
一般工业技术 | 5764篇 |
冶金工业 | 7764篇 |
原子能技术 | 175篇 |
自动化技术 | 3794篇 |
出版年
2023年 | 322篇 |
2022年 | 293篇 |
2021年 | 673篇 |
2020年 | 556篇 |
2019年 | 475篇 |
2018年 | 940篇 |
2017年 | 844篇 |
2016年 | 972篇 |
2015年 | 871篇 |
2014年 | 1040篇 |
2013年 | 1875篇 |
2012年 | 1431篇 |
2011年 | 1439篇 |
2010年 | 1209篇 |
2009年 | 1177篇 |
2008年 | 1298篇 |
2007年 | 1254篇 |
2006年 | 901篇 |
2005年 | 741篇 |
2004年 | 543篇 |
2003年 | 523篇 |
2002年 | 475篇 |
2001年 | 386篇 |
2000年 | 375篇 |
1999年 | 495篇 |
1998年 | 2453篇 |
1997年 | 1461篇 |
1996年 | 1015篇 |
1995年 | 641篇 |
1994年 | 525篇 |
1993年 | 476篇 |
1992年 | 208篇 |
1991年 | 220篇 |
1990年 | 182篇 |
1989年 | 189篇 |
1988年 | 170篇 |
1987年 | 177篇 |
1986年 | 164篇 |
1985年 | 241篇 |
1984年 | 198篇 |
1983年 | 191篇 |
1982年 | 140篇 |
1981年 | 204篇 |
1980年 | 198篇 |
1979年 | 147篇 |
1978年 | 124篇 |
1977年 | 241篇 |
1976年 | 507篇 |
1975年 | 100篇 |
1973年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Alinur Büyükaksoy 《电信纪事》1985,40(7-8):402-410
An asymptotic solution to the problem of the diffraction of high-frequency waves by the edge of a cylindrically curved surface whose convex and concave faces present soft and hard boundary conditions is obtained. The results permit us to define new diffraction coefficients related to this kind of mixed boundary conditions. When the radius of the curvature becomes infinitely large, the edgediffraction coefficient reduces to this known for the softhard half-plane. 相似文献
62.
63.
Gesellschaft für Informatik 《Informatik-Spektrum》2008,31(6):526-526
Ohne Zusammenfassung 相似文献
64.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time. 相似文献
65.
66.
67.
Jürgen Schönbeçk 《NTM》2004,12(2):80-99
Thomas Fincke (January 6th, 1561–April 24th, 1656), born in Flensburg (Germany), was one of the very most important and significant scientists in Denmark during the
seventeenth century, a mathematician and astrologer and physician in the beginning of modern science, a representative of
humanism and an influentual academic organizer. He studied in Strasbourg (since 1577) and Padua (since 1583) and received
his M.D. in Basel (1587), he practised as a physician throughout his life (since 1587 or 1590) and became a professor at Copenhagen
(1591). But he was best known because of his Geometriae rotundi libri XIIII (1583), a famous book on plane and spherical trigonometry, based not on Euclid but on Petrus Ramus. In this influentual work,
in which Fincke introduced the terms tangent and secant and probable first noticed the Law of Tangents and the so-called Newton-Oppel-Mauduit-Simpson-Mollweide-Gauss-formula,
he showed himself to be „abreast of the mathematics of his time“.
相似文献
68.
69.
In this article, we describe a knowledge-based controlled platform using program supervision techniques. This platform eases
the creation and the configuration of video surveillance systems. Several issues need to be addressed to provide a correct
system configuration: (1) to choose, among a library of programs, those which are best satisfying a given user request, (2)
to assign a correct value for each program parameter, (3) to evaluate performances and to guarantee a performance rate which
is satisfactory regarding end-user requirements. This platform is composed of three main components: the library of programs,
the knowledge base and the control component. The knowledge is either given by experts or learnt by the system. The control
is generic in the sense that it is independent of any application. To validate this platform, we have built and evaluated
six video surveillance systems which are featured with three properties: adaptability, reliability and real-time processing. 相似文献
70.
D. Knig S. Carvajal-Gonzalez A. M. Downs J. Vassy P. Rigaut 《Journal of microscopy》1991,161(3):405-433
Within the concept of point processes, a review is presented of quantities which can be used in studies of three-dimensional (3-D) aggregates of particles. Suitable characteristics and estimators are given for both unmarked and marked point processes. To demonstrate the feasibility of such quantitative approaches, an application in histology, dealing with 3-D arrangements of cell nuclei in rat liver, is described. Using a confocal scanning light microscope, 3-D images are recorded and image analysis used to obtain the coordinates of the centroid, together with the volume and DNA content, of each cell nucleus. Examples of results are given, using both unmarked and marked point processes. In the latter case, cell type, nuclear volume and ploidy group are suitable marks. 相似文献