全文获取类型
收费全文 | 5763篇 |
免费 | 679篇 |
国内免费 | 374篇 |
专业分类
电工技术 | 461篇 |
综合类 | 528篇 |
化学工业 | 1046篇 |
金属工艺 | 102篇 |
机械仪表 | 359篇 |
建筑科学 | 141篇 |
矿业工程 | 53篇 |
能源动力 | 280篇 |
轻工业 | 104篇 |
水利工程 | 56篇 |
石油天然气 | 176篇 |
武器工业 | 70篇 |
无线电 | 1573篇 |
一般工业技术 | 540篇 |
冶金工业 | 129篇 |
原子能技术 | 71篇 |
自动化技术 | 1127篇 |
出版年
2024年 | 23篇 |
2023年 | 103篇 |
2022年 | 116篇 |
2021年 | 153篇 |
2020年 | 176篇 |
2019年 | 177篇 |
2018年 | 158篇 |
2017年 | 185篇 |
2016年 | 204篇 |
2015年 | 257篇 |
2014年 | 374篇 |
2013年 | 398篇 |
2012年 | 440篇 |
2011年 | 460篇 |
2010年 | 357篇 |
2009年 | 355篇 |
2008年 | 325篇 |
2007年 | 392篇 |
2006年 | 329篇 |
2005年 | 263篇 |
2004年 | 215篇 |
2003年 | 216篇 |
2002年 | 176篇 |
2001年 | 158篇 |
2000年 | 141篇 |
1999年 | 130篇 |
1998年 | 101篇 |
1997年 | 78篇 |
1996年 | 80篇 |
1995年 | 63篇 |
1994年 | 40篇 |
1993年 | 47篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 18篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有6816条查询结果,搜索用时 15 毫秒
1.
2.
Navab SinghAuthor Vitae Moitreyee Mukherjee-RoyAuthor VitaeSohan Singh MehtaAuthor Vitae 《Microelectronics Journal》2003,34(4):237-245
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging. 相似文献
3.
G. Martinez 《Journal of Low Temperature Physics》2003,133(1-2):61-95
High magnetic fields are one of the most powerful tools available to scientists for the study, modification and control of matter. This includes the knowledge on correlations effects, interaction mechanisms, structural information and understanding of mesoscopic effects. In this context, a review of recent scientific achievements at the Grenoble High Magnetic Laboratory is given to illustrate, on specific examples, the power of the Magnetic Field probe. 相似文献
4.
5.
I. Belda X. Llorà E. Giralt 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2006,10(4):295-304
One of the goals of computational chemistry is the automated de novo design of bioactive molecules. Despite significant progress
in computational approaches to ligand design and efficient evaluation of binding energy, novel procedures for ligand design
are required. Evolutionary computation provides a new approach to this design issue. This paper presents an automated methodology
for computer-aided peptide design based on evolutionary algorithms. It provides an automatic tool for peptide de novo design,
based on protein surface patches defined by user. Regarding the restrictive constrains of this problem a special emphasis has been made on the design of the
evolutionary algorithms implemented. 相似文献
6.
Magnus Rnning Florian Huber Hilde Meland Hilde Venvik De Chen Anders Holmen 《Catalysis Today》2005,100(3-4):249-254
In order to investigate the effect of cerium oxide on Cu–Zn-based mixed-oxide catalysts four catalyst samples were characterized by means of XRD, in situ XANES and thermogravimetric analysis. The activity of the catalyst samples was tested for the forward water–gas shift reaction. Cerium oxide was found to increase the crystallinity of the ZnO phase indicating a segregation of the Cu and ZnO phases. The TOF of the water–gas shift reaction based on chemisorption data was found to be independent of composition and preparation conditions of the four catalyst samples. In contrast, the catalyst stability depends on composition and preparation conditions. Cerium oxide impregnated before calcination of the hydrotalcite-based Cu–Zn precursors leads to a more stable water–gas shift catalyst. 相似文献
7.
楼滨乔 《核电子学与探测技术》1993,(4)
本文对最基本的HCMOS器件(反相器和与非门)作了γ辐射损伤实验。通过器件性能变化,分析了γ辐射对电路的作用。 相似文献
8.
Michael Anthony Puso Tod A. Laursen 《International journal for numerical methods in engineering》2002,54(8):1161-1194
In this work, a method is developed for smoothing three‐dimensional contact surfaces. The method can be applied to both regular and irregular meshes. The algorithm employs Gregory patches to interpolate finite element nodes and provide tangent plane continuity between adjacent patches. The resulting surface interpolation is used to calculate gaps and contact forces, in a variationally consistent way, such that contact forces due to normal and frictional contact vary smoothly as slave nodes transition from one patch to the next. This eliminates the ‘chatter’ which typically occurs in a standard contact algorithm when a slave node is situated near a master facet edge. The elimination of this chatter provides a significant improvement in convergence behaviour, which is illustrated by a number of numerical examples. Furthermore, smoothed surfaces also provide a more accurate representation of the actual surface, such that resulting stresses and forces can be more accurately computed with coarse meshes in many problems. This fact is also demonstrated by the numerical examples. Published in 2002 by John Wiley & Sons, Ltd. 相似文献
9.
Interest in advanced modulation formats for optical communication systems has so far experienced two major waves. The first one was motivated by the potential to enhance receiver sensitivity of thermal noise-limited systems using coherent detection in combination with phase shift keying. It ended with the advent of optical amplification, enabling high sensitivities together with polarization insensitive, simple and stable direct detection. The second wave is still rolling, fueled by the potential of advanced modulation formats to increase robustness of optical transmission systems against signal distortions. Due to performance limitations given by direct detection and nonlinear effects in the transmission fiber, it is not decided yet, whether there will be widespread application in carrier networks. 相似文献
10.
S Fukuda 《Bulletin of Materials Science》1996,19(6):887-891
The conventional approach has put emphasis upon reducing labour, and increasing efficiency and uniformity. But this holds
good only in the mass production paradigm. As we are entering the age of small production with far wider varieties, these
principles of yesterday should be re-examined. Labour itself sometimes gives satisfaction if it involves the joy of creation,
and longer time does not necessarily mean just patience, it sometimes turns into expectation if greater joy will be provided
later. Too much fitness for the purpose sometimes means lack of robustness and adaptability to the quickly and widely changing
environment. Thus, we should reconsider the items we thought important in the mass production age to aptly cope with the diversification
of each customer’s requirements. 相似文献