全文获取类型
收费全文 | 752109篇 |
免费 | 8469篇 |
国内免费 | 2081篇 |
专业分类
电工技术 | 14192篇 |
综合类 | 682篇 |
化学工业 | 116447篇 |
金属工艺 | 32216篇 |
机械仪表 | 23828篇 |
建筑科学 | 17471篇 |
矿业工程 | 4707篇 |
能源动力 | 19032篇 |
轻工业 | 63106篇 |
水利工程 | 8389篇 |
石油天然气 | 15917篇 |
武器工业 | 42篇 |
无线电 | 83377篇 |
一般工业技术 | 149521篇 |
冶金工业 | 135565篇 |
原子能技术 | 17451篇 |
自动化技术 | 60716篇 |
出版年
2021年 | 6537篇 |
2019年 | 6270篇 |
2018年 | 10790篇 |
2017年 | 10932篇 |
2016年 | 11587篇 |
2015年 | 7474篇 |
2014年 | 12505篇 |
2013年 | 34184篇 |
2012年 | 19607篇 |
2011年 | 26693篇 |
2010年 | 21511篇 |
2009年 | 23921篇 |
2008年 | 24637篇 |
2007年 | 24414篇 |
2006年 | 21513篇 |
2005年 | 19502篇 |
2004年 | 18628篇 |
2003年 | 18395篇 |
2002年 | 17969篇 |
2001年 | 17628篇 |
2000年 | 16692篇 |
1999年 | 16803篇 |
1998年 | 40221篇 |
1997年 | 29013篇 |
1996年 | 22520篇 |
1995年 | 17171篇 |
1994年 | 15458篇 |
1993年 | 15047篇 |
1992年 | 11448篇 |
1991年 | 11171篇 |
1990年 | 10733篇 |
1989年 | 10491篇 |
1988年 | 10163篇 |
1987年 | 9033篇 |
1986年 | 8823篇 |
1985年 | 10109篇 |
1984年 | 9130篇 |
1983年 | 8600篇 |
1982年 | 7835篇 |
1981年 | 7993篇 |
1980年 | 7628篇 |
1979年 | 7549篇 |
1978年 | 7470篇 |
1977年 | 8510篇 |
1976年 | 11275篇 |
1975年 | 6672篇 |
1974年 | 6385篇 |
1973年 | 6422篇 |
1972年 | 5529篇 |
1971年 | 5101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The trends in high density interconnection (HDI) multichip module (MCM) techniques that have the potential to reduce interconnection cost and production time are described. The implementation in laminated dielectric (MCM-L) technology of a workstation processor core illustrates current substrate technology capabilities. The design, routing, layout and thermal management of the processor core are described. Thin-film deposited dielectric (MCM-D) technology is discussed as a cost-effective method for future interconnection applications 相似文献
102.
Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented 相似文献
103.
Garner H.R. Balog R.P. Luebke K.J. 《IEEE engineering in medicine and biology magazine》2002,21(4):123-125
Given the enormous size of the genome and that there are potentially many other types of measurements we need to do to understand it, it has become necessary to pick and choose one's targets to measure because it is still impossible to evaluate the entire genome all at once. What has emerged is a need to have rapidly customizable microarrays. There are two dominant methods to accomplish custom microarray synthesis, Affymetrix-like microarrays manufactured using light projection rather than semiconductor-like masks used by Affymetrix to mass manufacture their GeneChip/sup TM/ arrays now, or the ink-jet printing method employed by Agilent. The manufacture of these custom Affymetrix-like microarrays can now be done on a digital optical chemistry (DOC) machine developed at the University of Texas Southwestern Medical Center, and this method offers much higher feature numbers and feature density than is possible with ink-jet printed arrays. On a microarray, each feature contains a single genetic measurement. The initial DOC prototype has been described in several publications, but that has now led to a second-generation machine. This machine reliably produces a number of arrays daily, has been deployed against a number of biomedical questions, is being used in new ways and has also led to a number of spin-off technologies. 相似文献
104.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989. 相似文献
105.
A. A. Konstantinov N. V. Kurenkov A. B. Malinin T. E. Sazonova S. V. Sepman 《Atomic Energy》1989,67(3):696-698
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989. 相似文献
106.
Nagpal R. Zambonelli F. Sirer E.G. Chaouchi H. Smirnov M. 《Intelligent Systems, IEEE》2006,21(2):50-58
No generally accepted principles and guidelines currently exist to help engineers design local interaction mechanisms that result in a desired global behavior. However, several communities have developed ways of approaching this problem in the context of niched application areas. Because the ideas underlying these approaches are often obscured or underemphasized in technical papers, the authors review the role of self-organization in their work. They provide a better picture of the status of the emerging field of self-organizing systems or autonomic computing. 相似文献
107.
108.
Hayashi M. Tanaka H. Ohara K. Otani T. Suzuki M. 《Lightwave Technology, Journal of》2002,20(2):236-242
An all-optical multiplexing technique using wavelength division multiplexing (WDM)-time division multiplexing (TDM) conversion with an electroabsorption wavelength converter has been proposed and demonstrated. The effectiveness of this WDM-TDM conversion technique for various pulsewidth settings was experimentally investigated. The fluctuation of the signal performance, which was inevitably caused by the coherent crosstalk between adjacent pulses in the conventional optical time division multiplexing (OTDM) technique, were successfully suppressed, even in the case of wide pulse duration. High Q-factor performance has been maintained for a wide range of duty ration from 36% to 74%. By introducing this technique to the optical time division multiplexer, a highly stable and high-quality 40-Gb/s optical signal can be effectively produced without generating the short pulse or setting two tributaries at orthogonal polarization states, and without introducing high-speed electronics for signal multiplexing. The WDM-TDM conversion with an electroabsorption wavelength converter was extended to 60-Gb/s operation by using three 20-Gb/s tributaries. A clear eye opening was confirmed for a waveform after the WDM-TDM conversion of the 60-Gb/s signal 相似文献
109.
A.S. Fraser 《Journal of Great Lakes research》1980,6(1):83-87
An apparent decrease in total phosphorus concentrations of approximately 4.l μgP/L has been reported recently for the spring values of 1977 and 1978 in Lake Ontario. Investigation of the loading reduction for this period independent of sedimentation factors can account for only 10% of the change. The results indicate that changes in the sedimentation rate of total phosphorus during this period offer an explanation for the majority of the change in concentration. 相似文献
110.
K. A. Abdikalikov V. K. Zadiraka O. S. Kondratenko S. S. Mel'nikova 《Cybernetics and Systems Analysis》1991,27(3):414-419
A fast algorithm is proposed for estimating the auto- and cross-correlation functions of a large signal. The algorithm is based on the sectioning method by the fast Fourier transform. We determine the optimal length of the portion of data read from external memory into RAM which achieves Tmin—a minimum processing time. An estimate of Tmin is obtained.Translated from Kibernetika, No. 3, pp. 78–81, May–June, 1991. 相似文献