首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   868629篇
  免费   10549篇
  国内免费   2198篇
电工技术   16064篇
综合类   785篇
化学工业   134855篇
金属工艺   33952篇
机械仪表   26882篇
建筑科学   21398篇
矿业工程   4985篇
能源动力   22423篇
轻工业   75218篇
水利工程   9316篇
石油天然气   16424篇
武器工业   52篇
无线电   99287篇
一般工业技术   170697篇
冶金工业   154956篇
原子能技术   18496篇
自动化技术   75586篇
  2021年   7623篇
  2020年   5810篇
  2019年   6990篇
  2018年   11870篇
  2017年   12123篇
  2016年   12820篇
  2015年   8540篇
  2014年   14192篇
  2013年   40342篇
  2012年   22697篇
  2011年   31246篇
  2010年   24888篇
  2009年   27808篇
  2008年   28783篇
  2007年   28678篇
  2006年   25191篇
  2005年   22935篇
  2004年   22172篇
  2003年   21625篇
  2002年   20909篇
  2001年   20569篇
  2000年   19421篇
  1999年   19708篇
  1998年   45587篇
  1997年   33206篇
  1996年   25985篇
  1995年   20156篇
  1994年   18117篇
  1993年   17626篇
  1992年   13517篇
  1991年   12956篇
  1990年   12724篇
  1989年   12301篇
  1988年   11808篇
  1987年   10412篇
  1986年   10170篇
  1985年   11941篇
  1984年   11025篇
  1983年   10089篇
  1982年   9262篇
  1981年   9300篇
  1980年   8895篇
  1979年   8931篇
  1978年   8628篇
  1977年   9825篇
  1976年   12701篇
  1975年   7578篇
  1974年   7248篇
  1973年   7209篇
  1972年   6116篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Functional Properties and Food Applications of Rapeseed Protein Concentrate   总被引:1,自引:0,他引:1  
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   
122.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  相似文献   
123.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  相似文献   
124.
J. Perahia comments on the paper by J. S. Hsu (see ibid., vol.16, p.192-7, 2001) and expands on the case of a two stator three phase squirrel cage induction machine where one stator housing is stationary and other stator housing is mounted on a worm gear assembly. The original author replies to the comments  相似文献   
125.
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   
126.
An investigation into the effects of pressure (helium gas) on the isothermal fluid behavior includes: (1) the effect of pressure on the rate of melting and coking as evidenced by the rate constants k(melt) and k(coke); (2) the effect of pressure on the energies of activation of melting and coking; (3) the effects of pressure on the characteristic times; (4) the effects of pressure on the maximum isothermal fluidity. Results from the effects of pressure on k(melt) revealed that it was generally the high total sulfur, low nitrogen, low reactives/mineral matter ratio, medium rank coals which show the greatest increase in k(melt), whereas the highest rank coals show the least decrease in k(coke). The energies of activation of melting and coking were not significantly affected by pressure. The investigation also reveals increases or decreases in the respective times of softening, maximum fluidity, resolidification and total time of fluid behavior under isothermal pressurized conditions. There appears the possibility that these shifts may be rank dependent. Additionally, the lower rank coals show the largest relative increase in their fluidities when subjected to pressure. Empirical relationships were derived in order to quantitatively predict the maximum isothermal fluidity for most (fluid) coals at a given pressure.  相似文献   
127.
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   
128.
129.
130.
This paper demonstrates the use of computer simulation for topological design and performance engineering of transparent wavelength-division multiplexing metropolitan-area networks. Engineering of these networks involves the study of various transport-layer impairments such as amplifier noise, component ripple, chirp/dispersion, optical crosstalk, waveform distortion due to filter concatenation, fiber nonlinearities, and polarization effects. A computer simulation methodology composed of three main simulation steps is derived and implemented. This methodology obtains performance estimations by applying efficient wavelength-domain simulations on the entire network topology, followed by time-/frequency-domain simulations on selected paths of the network and finally Q-budgeting on an identified worst case path. The above technique provides an efficient tool for topological design and network performance engineering. Accurate simulation models are presented for each of the performance impairments, and the computer simulation methodology is used for the design and engineering of a number of actual metro network architectures  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号