全文获取类型
收费全文 | 318944篇 |
免费 | 4692篇 |
国内免费 | 726篇 |
专业分类
电工技术 | 6334篇 |
综合类 | 565篇 |
化学工业 | 49216篇 |
金属工艺 | 10545篇 |
机械仪表 | 9127篇 |
建筑科学 | 8233篇 |
矿业工程 | 894篇 |
能源动力 | 9003篇 |
轻工业 | 32842篇 |
水利工程 | 2646篇 |
石油天然气 | 3713篇 |
武器工业 | 10篇 |
无线电 | 40187篇 |
一般工业技术 | 59910篇 |
冶金工业 | 57280篇 |
原子能技术 | 5509篇 |
自动化技术 | 28348篇 |
出版年
2021年 | 2711篇 |
2019年 | 2477篇 |
2018年 | 4065篇 |
2017年 | 3913篇 |
2016年 | 4063篇 |
2015年 | 2913篇 |
2014年 | 4940篇 |
2013年 | 15187篇 |
2012年 | 8010篇 |
2011年 | 10763篇 |
2010年 | 8376篇 |
2009年 | 9652篇 |
2008年 | 10042篇 |
2007年 | 9935篇 |
2006年 | 8795篇 |
2005年 | 8083篇 |
2004年 | 7935篇 |
2003年 | 7669篇 |
2002年 | 7478篇 |
2001年 | 7636篇 |
2000年 | 7299篇 |
1999年 | 7632篇 |
1998年 | 17870篇 |
1997年 | 12984篇 |
1996年 | 10205篇 |
1995年 | 7949篇 |
1994年 | 7260篇 |
1993年 | 6948篇 |
1992年 | 5308篇 |
1991年 | 5083篇 |
1990年 | 4967篇 |
1989年 | 4803篇 |
1988年 | 4693篇 |
1987年 | 3901篇 |
1986年 | 4025篇 |
1985年 | 4749篇 |
1984年 | 4318篇 |
1983年 | 4063篇 |
1982年 | 3627篇 |
1981年 | 3788篇 |
1980年 | 3487篇 |
1979年 | 3440篇 |
1978年 | 3233篇 |
1977年 | 3833篇 |
1976年 | 4875篇 |
1975年 | 2792篇 |
1974年 | 2668篇 |
1973年 | 2681篇 |
1972年 | 2217篇 |
1971年 | 1967篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
1.
One specific class of non-linear evolution equations, known as the Tzitzéica-type equations, has received great attention from a group of researchers involved in non-linear science. In this article, new exact solutions of the Tzitzéica-type equations arising in non-linear optics, including the Tzitzéica, Dodd–Bullough–Mikhailov and Tzitzéica–Dodd–Bullough equations, are obtained using the expa function method. The integration technique actually suggests a useful and reliable method to extract new exact solutions of a wide range of non-linear evolution equations. 相似文献
2.
Ryszard Żywica Monika Modzelewska-Kapituła Katarzyna Tkacz 《International Journal of Food Properties》2018,21(1):1386-1394
The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values. 相似文献
3.
4.
5.
6.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch 下载免费PDF全文
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
7.
8.
M. R. Thompson 《Drug development and industrial pharmacy》2015,41(8):1223-1231
Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique. 相似文献
9.
10.