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   696916篇
  免费   9821篇
  国内免费   2017篇
电工技术   12937篇
综合类   668篇
化学工业   104448篇
金属工艺   30068篇
机械仪表   22696篇
建筑科学   16913篇
矿业工程   3500篇
能源动力   18153篇
轻工业   58219篇
水利工程   7170篇
石油天然气   12192篇
武器工业   39篇
无线电   77862篇
一般工业技术   136894篇
冶金工业   130748篇
原子能技术   13788篇
自动化技术   62459篇
  2021年   5822篇
  2020年   4158篇
  2019年   5338篇
  2018年   14883篇
  2017年   15153篇
  2016年   12700篇
  2015年   6985篇
  2014年   11009篇
  2013年   29551篇
  2012年   19349篇
  2011年   30040篇
  2010年   24783篇
  2009年   26309篇
  2008年   26477篇
  2007年   27661篇
  2006年   18808篇
  2005年   19757篇
  2004年   17924篇
  2003年   17301篇
  2002年   15871篇
  2001年   15529篇
  2000年   14551篇
  1999年   15277篇
  1998年   39539篇
  1997年   27716篇
  1996年   21186篇
  1995年   15955篇
  1994年   13794篇
  1993年   13488篇
  1992年   9738篇
  1991年   9188篇
  1990年   8959篇
  1989年   8741篇
  1988年   8194篇
  1987年   7311篇
  1986年   7151篇
  1985年   8015篇
  1984年   7486篇
  1983年   6704篇
  1982年   6315篇
  1981年   6426篇
  1980年   6056篇
  1979年   5976篇
  1978年   5723篇
  1977年   6927篇
  1976年   9062篇
  1975年   4975篇
  1974年   4735篇
  1973年   4866篇
  1972年   4003篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
4.
Gelatin is one of the most important multifunctional biopolymers and is widely used as an essential ingredient in food, pharmaceutical, and cosmetics. Porcine gelatin is regarded as the leading source of gelatin globally then followed by bovine gelatin. Porcine sources are favored over other sources since they are less expensive. However, porcine gelatin is religiously prohibited to be consumed by Muslims and the Jewish community. It is predicted that the global demand for gelatin will increase significantly in the future. Therefore, a sustainable source of gelatin with efficient production and free of disease transmission must be developed. The highest quality of Bovidae-based gelatin (BG) was acquired through alkaline pretreatment, which displayed excellent physicochemical and rheological properties. The utilization of mammalian- and plant-based enzyme significantly increased the gelatin yield. The emulsifying and foaming properties of BG also showed good stability when incorporated into food and pharmaceutical products. Manipulation of extraction conditions has enabled the development of custom-made gelatin with desired properties. This review highlighted the various modifications of extraction and processing methods to improve the physicochemical and functional properties of Bovidae-based gelatin. An in-depth analysis of the crucial stage of collagen breakdown is also discussed, which involved acid, alkaline, and enzyme pretreatment, respectively. In addition, the unique characteristics and primary qualities of BG including protein content, amphoteric property, gel strength, emulsifying and viscosity properties, and foaming ability were presented. Finally, the applications and prospects of BG as the preferred gelatin source globally were outlined.  相似文献   
5.
6.
Journal of Computer and Systems Sciences International - It is shown that the Lyapunov theorem on the distribution properties of the sum of random variables with different distribution densities...  相似文献   
7.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  相似文献   
8.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
9.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
10.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  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