全文获取类型
收费全文 | 746285篇 |
免费 | 8345篇 |
国内免费 | 1712篇 |
专业分类
电工技术 | 14003篇 |
综合类 | 625篇 |
化学工业 | 115117篇 |
金属工艺 | 29635篇 |
机械仪表 | 23472篇 |
建筑科学 | 17337篇 |
矿业工程 | 4817篇 |
能源动力 | 19718篇 |
轻工业 | 60419篇 |
水利工程 | 8421篇 |
石油天然气 | 16393篇 |
武器工业 | 49篇 |
无线电 | 84808篇 |
一般工业技术 | 150253篇 |
冶金工业 | 132726篇 |
原子能技术 | 17535篇 |
自动化技术 | 61014篇 |
出版年
2021年 | 6921篇 |
2020年 | 5092篇 |
2019年 | 6523篇 |
2018年 | 11175篇 |
2017年 | 11434篇 |
2016年 | 11915篇 |
2015年 | 7522篇 |
2014年 | 12824篇 |
2013年 | 34241篇 |
2012年 | 19938篇 |
2011年 | 27055篇 |
2010年 | 21772篇 |
2009年 | 24306篇 |
2008年 | 24877篇 |
2007年 | 24585篇 |
2006年 | 21422篇 |
2005年 | 19257篇 |
2004年 | 18431篇 |
2003年 | 18309篇 |
2002年 | 17517篇 |
2001年 | 17453篇 |
2000年 | 16495篇 |
1999年 | 16678篇 |
1998年 | 40142篇 |
1997年 | 28590篇 |
1996年 | 22255篇 |
1995年 | 16930篇 |
1994年 | 15270篇 |
1993年 | 15018篇 |
1992年 | 11278篇 |
1991年 | 10996篇 |
1990年 | 10773篇 |
1989年 | 10350篇 |
1988年 | 10016篇 |
1987年 | 8912篇 |
1986年 | 8685篇 |
1985年 | 9752篇 |
1984年 | 8810篇 |
1983年 | 8504篇 |
1982年 | 7701篇 |
1981年 | 7766篇 |
1980年 | 7481篇 |
1979年 | 7368篇 |
1978年 | 7135篇 |
1977年 | 8145篇 |
1976年 | 10478篇 |
1975年 | 6343篇 |
1974年 | 6140篇 |
1973年 | 6114篇 |
1972年 | 5303篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Rapeseed protein concentrate (RC), prepared with 2% hexameta-phosphate, was tested for its functionality and performance in some foods. The RC had good nitrogen solubility, fat absorption, emulsification, and whipping capacities but poor water absorption and gelling properties. It increased the emulsion stability, and protein but lowered the fat content of wieners. It also increased the cooking yield, reduced the shrinkage and tenderized meat patties. Results were similar to soybean isolate except for the poorer color and flavor. The cooking yield of RC supplemented wieners was less than the all-meat control and soybean-supplemented wieners. A 9% RC dispersion mixed with an equal volume of eggwhite produced a meringue of comparable stability and texture to that of eggwhite alone. 相似文献
112.
The dynamic and equilibrium swelling behavior of polystyrene microparticles crosslinked with divinyl benzene was investigated in methyl ethyl ketone and cyclohexane. The dynamic studies gave new information about the mechanism of penetrant transport in this polymer. The equilibrium studies were used to determine important parameters of the crosslinked structure of these systems, including the average molecular weight between crosslinks, M?c 相似文献
113.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989. 相似文献
114.
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
115.
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
116.
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
117.
Banded textures produced in a thermotropic liquid crystal polymer by shearing between glass slides are examined by using both transmission electron and polarized light microscopy. The periodic variation in director orientation about the shear axis, as measured by light microscopy, is shown to be distinctly different from that indicated by electron diffraction. Measurements of birefringence and observation of Zernicke phase contrast indicate periodic variations in optical properties of the polymer, in step with the bands. Such effects are accounted for in terms of a synchronous rotation of the planar aromatic groups about the molecular chain axes. Evidence for an out-of-plane component of molecular orientation is also presented. 相似文献
118.
A simple apparatus for elongational test of molten polymers is presented. Its realiability is demonstrated by means of stress growth in constant stretching rate experiments and relaxation test on a low density polyethylene sample. 相似文献
119.
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
120.