全文获取类型
收费全文 | 157649篇 |
免费 | 1645篇 |
国内免费 | 1094篇 |
专业分类
电工技术 | 2196篇 |
综合类 | 2363篇 |
化学工业 | 22413篇 |
金属工艺 | 8185篇 |
机械仪表 | 5626篇 |
建筑科学 | 3776篇 |
矿业工程 | 1064篇 |
能源动力 | 2939篇 |
轻工业 | 9895篇 |
水利工程 | 2104篇 |
石油天然气 | 2644篇 |
武器工业 | 41篇 |
无线电 | 16360篇 |
一般工业技术 | 32550篇 |
冶金工业 | 15015篇 |
原子能技术 | 2873篇 |
自动化技术 | 30344篇 |
出版年
2022年 | 575篇 |
2021年 | 904篇 |
2020年 | 697篇 |
2019年 | 782篇 |
2018年 | 15910篇 |
2017年 | 14846篇 |
2016年 | 11635篇 |
2015年 | 1536篇 |
2014年 | 1774篇 |
2013年 | 3738篇 |
2012年 | 5455篇 |
2011年 | 12142篇 |
2010年 | 10568篇 |
2009年 | 8125篇 |
2008年 | 9313篇 |
2007年 | 10243篇 |
2006年 | 2287篇 |
2005年 | 3094篇 |
2004年 | 2946篇 |
2003年 | 2944篇 |
2002年 | 2232篇 |
2001年 | 1773篇 |
2000年 | 1843篇 |
1999年 | 1619篇 |
1998年 | 3722篇 |
1997年 | 2624篇 |
1996年 | 1980篇 |
1995年 | 1530篇 |
1994年 | 1337篇 |
1993年 | 1357篇 |
1992年 | 1005篇 |
1991年 | 1074篇 |
1990年 | 1073篇 |
1989年 | 1052篇 |
1988年 | 949篇 |
1987年 | 875篇 |
1986年 | 878篇 |
1985年 | 936篇 |
1984年 | 780篇 |
1983年 | 767篇 |
1982年 | 676篇 |
1981年 | 692篇 |
1980年 | 663篇 |
1979年 | 646篇 |
1978年 | 621篇 |
1977年 | 776篇 |
1976年 | 933篇 |
1975年 | 581篇 |
1974年 | 551篇 |
1973年 | 546篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
K. O. Sabdenov 《Combustion, Explosion, and Shock Waves》1993,29(5):568-576
The laminar flame theory under the condition of minimum entropy production is presented. The equation of the temperature boundary
layer is obtained for Le=0, and its general solution is found. It is shown that the mechanism of laminar flame propagation
can be treated from the viewpoint of stationary thermal explosion in a cylindrical vessel of radius 2 as the critical regime
in which the burnup is taken into account in an unusual form.
Tomsk. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 5, pp. 22–30, September–October, 1993 相似文献
92.
O. P. Minaev 《Soil Mechanics and Foundation Engineering》1994,31(4):141-144
Various methods of sounding were investigated for evaluating the quality of compacting water-saturated fine and medium sands.
A comparative analysis of the data obtained with the data of direct soil sampling was carried out. The given recommendations
can be used when preparing the new edition of the building codes for engineering surveys for construction.
Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 17–20, July–August, 1994 相似文献
93.
Kerlavage A.R. FitzHugh W. Gladek A. Kelley J. Scott J. Shirley R. Sutton G. Man Wai-Chiu White O. Adams D. 《IEEE engineering in medicine and biology magazine》1995,14(6):710-717
The rapid advances in molecular biology have begun to shift many of the bottlenecks in genome research from the laboratory to the data analysis facility. The pace at which this has occurred creates a situation in which software development always has to catch up with the flow of data. Since such large-scale processes were not anticipated, the analysis infrastructure has not been fully established. Furthermore, most systems that have been built were designed by the biologists who collected the data. More recently, computer scientists, mathematicians, and engineers have taken an interest in this problem. This has had a positive effect, since it has created a tight synergy between the informatics and the biology. Several principles affected the design of the system developed at TIGR. Each of the sample preparation, sequencing, and analysis steps had to be managed, scheduled, and tracked. This information had to be made readily available to those who needed it for carrying out their tasks. Different skill levels of the users had to be taken into account. The degree of human intervention at each step had to be evaluated and built into the design. A mixed processing environment of Macintosh and Unix platforms had to be integrated. Most importantly, the system had to save time, reduce error, and ensure uniformity of the analysis and quality of the results. In the authors' experience, the tools they have built work well because of their early decisions as to which systems to use for development. The authors settled on a robust relational database management system (Sybase) and a portable development environment (C, C++) 相似文献
94.
Arafa M. Fay P. Ismail K. Chu J.O. Meyerson B.S. Adesida I. 《Electron Device Letters, IEEE》1996,17(3):124-126
We report on the fabrication and characterization of high-speed p-type modulation-doped field-effect transistors (MODFETs) with 0.7-μm and 1-μm gate-lengths having unity current-gain cut-off frequencies (fT) of 9.5 GHz and 5.3 GHz, respectively. The devices were fabricated on a high hole mobility SiGe heterostructure grown by ultra-high-vacuum chemical vapor deposition (UHV-CVD). The dc maximum extrinsic transconductance (gm) is 105 mS/mm (205 mS/mm) at room temperature (77 K) for the 0.7-μm gate length devices. The fabricated devices show good pinch-off characteristics and have a very low gate leakage current of a few μA/mm at room temperature and a few nA/mm at 77 K 相似文献
95.
O. N. Zavrazhnaya I. N. Oleinikov E. D. Naumov V. V. Petrov 《Chemical and Petroleum Engineering》1993,29(11):555-559
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 11, pp. 28–30, November, 1993. 相似文献
96.
Baghai-Ravary L. Beet S.W. Tokhi M.O. 《Vision, Image and Signal Processing, IEE Proceedings -》1996,143(6):337-343
The authors describe and discuss the new technique, multistep adaptive flux interpolation (MAFI), and its application to image data for coding. When applied to an image, MAFI produces an output which is also in an image form, but which has a more uniform feature density and a greatly reduced size. MAFI warps the input image by removing those rows and columns which contain a majority of redundant pixels. The side information required for reconstruction is minimal, and the image can be further compressed using conventional coders, making the compression ratio even higher. Because of its warped nature, the MAFI output's statistics are also more consistent with the properties assumed by block-based discrete cosine transform (DCT) methods 相似文献
97.
V. E. Gul O. A. Sdobnikova A. L. Peshehonova L. G. Samoilova O. A. Khanchech A. I. Suvorova 《Polymer Engineering and Science》1993,33(22):1489-1493
Reported is an attempt to attain orientation of macromolecules during extrusion of films of cellulose derivatives that led to the liquid-crystalline state of a polymer and resulted in enhanced film strength. 相似文献
98.
99.
Scientific-Technical Center “Atomtekhénergo.” Leningrad Nuclear Power Plant. N. V. Sultanov Institute of Nuclear Reactors,
Russian Scientific Center “Kurchatovskii institut.” Translated from Atomnaya énergiya, Vol. 76, No. 6, pp. 470–473, June,
1994. 相似文献
100.