全文获取类型
收费全文 | 310290篇 |
免费 | 3736篇 |
国内免费 | 721篇 |
专业分类
电工技术 | 6196篇 |
综合类 | 561篇 |
化学工业 | 46813篇 |
金属工艺 | 10336篇 |
机械仪表 | 8831篇 |
建筑科学 | 7902篇 |
矿业工程 | 862篇 |
能源动力 | 8588篇 |
轻工业 | 31108篇 |
水利工程 | 2532篇 |
石油天然气 | 3669篇 |
武器工业 | 8篇 |
无线电 | 39768篇 |
一般工业技术 | 58591篇 |
冶金工业 | 56718篇 |
原子能技术 | 5461篇 |
自动化技术 | 26803篇 |
出版年
2021年 | 2288篇 |
2019年 | 2143篇 |
2018年 | 3615篇 |
2017年 | 3460篇 |
2016年 | 3553篇 |
2015年 | 2548篇 |
2014年 | 4461篇 |
2013年 | 14302篇 |
2012年 | 7390篇 |
2011年 | 10142篇 |
2010年 | 7921篇 |
2009年 | 9148篇 |
2008年 | 9628篇 |
2007年 | 9604篇 |
2006年 | 8519篇 |
2005年 | 7905篇 |
2004年 | 7767篇 |
2003年 | 7521篇 |
2002年 | 7351篇 |
2001年 | 7555篇 |
2000年 | 7216篇 |
1999年 | 7552篇 |
1998年 | 17679篇 |
1997年 | 12848篇 |
1996年 | 10115篇 |
1995年 | 7882篇 |
1994年 | 7214篇 |
1993年 | 6912篇 |
1992年 | 5297篇 |
1991年 | 5069篇 |
1990年 | 4943篇 |
1989年 | 4786篇 |
1988年 | 4678篇 |
1987年 | 3889篇 |
1986年 | 4012篇 |
1985年 | 4726篇 |
1984年 | 4279篇 |
1983年 | 4024篇 |
1982年 | 3605篇 |
1981年 | 3765篇 |
1980年 | 3458篇 |
1979年 | 3419篇 |
1978年 | 3227篇 |
1977年 | 3815篇 |
1976年 | 4850篇 |
1975年 | 2781篇 |
1974年 | 2661篇 |
1973年 | 2676篇 |
1972年 | 2215篇 |
1971年 | 1963篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
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
112.
113.
M.G. Pujar N. Parvathavarthini Sidhartha S. Jena B.V.R. Tata R.K. Dayal H.S. Khatak 《Journal of Materials Engineering and Performance》2008,17(6):793-801
In the present work 316LN as well as 316 stainless steel (SS) coupons each of dimensions (0.025 × 0.018 × 0.006 m3) in well-polished condition were used as two nominal electrodes which were immersed in the aerated solution of 0.5 M NaCl.
Correlated current and potential electrochemical noise (EN) signals were collected at 1 Hz sampling frequency for 1 h daily
over a period of 30 days. The detrended EN data were used to calculate the noise resistance (R
N) as well as the spectral noise resistance at zero frequency (R
SNo) values and other statistical parameters. To study the nature of pits and distribution of their diameters as well as depths,
extensive observations of the pitted and the blank specimens were carried out using Confocal Laser Scanning Microscopy (CLSM).
The current and the potential records of the two alloys showed distinct differences in their corrosion behavior. It was observed
that within less than 4 h of immersion, 316SS showed signals indicative of unstable pitting and onset of stable pitting was
noticed after 48 h of exposure. However, until about 24 h, 316LN showed just the random signals and unstable pitting was observed
after 28 h. The signals clearly indicated continuous growth of the stable pits in 316SS as against the repassivation of the
unstable pits in 316LN after 7 days exposure. It was observed that R
N values showed a continuous decrease in the case of 316SS, but were quite stable in the case of 316LN over the exposure period.
Concurrent to these observations it was observed that 316SS specimen was extensively pitted. The frequency distributions of
pit diameters as well pit depths were observed to be highest at 10-20 μm and 5-10 μm, respectively. However, pits with as
large as 70-80 μm diameter and as deep as 20-25 μm too were observed. No pits were observed in case of 316LN even after 30 days
of exposure, an observation that corroborates well with the stable R
N values. Thus, in the present investigation, the long-term tests using EN technique coupled with CLSM studies conclusively
prove that many unstable pits initiated in 316SS turn into stable ones resulting in insidious localized corrosion attack whereas
the unstable pits initiated in 316LN get passivated in the simulated coastal environment. 相似文献
114.
R. Wongmaneerung W. Chaisan O. Khamman R. Yimnirun S. Ananta 《Ceramics International》2008,34(4):813-817
The potential of the vibro-milling technique as a simple method to obtain usable quantities of single-phase electroceramic powders with nanosized particles was examined. A detailed study considering the role of both milling time and firing condition on phase formation and particle size of the final product was performed. The calcination temperature for the formation of the desired phase was lower when longer milling times have been applied. More importantly, by employing an appropriate choice of the milling time and calcination condition, high purity electroceramic nanopowders have been successfully prepared with a simple solid-state reaction method. 相似文献
115.
Oxide films were deposited on different substrates by laser molecular beam epitaxy. Reflection high-energy electron diffraction was performed to in situ investigate the change of growth mode and the lattice relaxation during the growth. An asymmetrical phenomenon was found in the two kinds of strain states, compressive stress and tensile stress of heterostructures with different lattice mismatch. In the case of BaTiO3/SrTiO3 (2.2%), 2D layer-by-layer growth mode without lattice relaxation can be maintained for a longer period for BTO films on STO with compressive stress, comparing to STO films on BTO with tensile stress. When MgO films were deposited on SrTiO3 with a large mismatch of 7.8%, compressive stress leads to rapid lattice relaxation with a very thin wet layer, and 3D strained island were observed. As a comparison, SrTiO3 films on MgO with tensile stress were configured. No RHEED patterns can be observed duo to a large tensile stress. 相似文献
116.
Permeable reactive barrier for groundwater remediation 总被引:4,自引:0,他引:4
R. Thiruvenkatachari S. Vigneswaran R. Naidu 《Journal of Industrial and Engineering Chemistry》2008,14(2):145-156
This article aims to provide an overview of the upcoming technology of permeable reactive barriers for groundwater remediation. A comprehensive list of references and web-links are also provided for further in-depth understanding. A brief discussion on the Australian perspective on this emerging technology is also included. 相似文献
117.
The possibility is demonstrated of using an addition of periclase-chromite filler (PCF) prepared from PCF grade broken material
articles in medium-cement concrete with chamotte filler. The effect of this addition on cement hardening duration, strength
and heat resistance is considered.
Translated from Novye Ogneupory, No. 8, pp. 42–46, August 2008. 相似文献
118.
119.
Becker-Gomez A. Lakshmi Viswanathan T. Viswanathan T.R. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(7):609-613
120.
Chaves R. Kuzmanov G. Sousa L. Vassiliadis S. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2008,16(8):999-1008