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   486307篇
  免费   6994篇
  国内免费   1256篇
电工技术   8929篇
综合类   702篇
化学工业   73209篇
金属工艺   17359篇
机械仪表   13969篇
建筑科学   12337篇
矿业工程   2114篇
能源动力   12864篇
轻工业   46718篇
水利工程   4654篇
石油天然气   7217篇
武器工业   17篇
无线电   58105篇
一般工业技术   93085篇
冶金工业   91503篇
原子能技术   9636篇
自动化技术   42139篇
  2021年   3938篇
  2019年   3792篇
  2018年   6355篇
  2017年   6216篇
  2016年   6508篇
  2015年   4537篇
  2014年   7580篇
  2013年   22763篇
  2012年   12341篇
  2011年   16581篇
  2010年   13199篇
  2009年   14966篇
  2008年   15435篇
  2007年   15392篇
  2006年   13369篇
  2005年   12353篇
  2004年   12057篇
  2003年   11689篇
  2002年   11174篇
  2001年   11379篇
  2000年   10940篇
  1999年   11495篇
  1998年   27952篇
  1997年   20088篇
  1996年   15709篇
  1995年   11845篇
  1994年   10831篇
  1993年   10452篇
  1992年   7886篇
  1991年   7544篇
  1990年   7280篇
  1989年   7219篇
  1988年   7000篇
  1987年   5900篇
  1986年   5951篇
  1985年   6988篇
  1984年   6393篇
  1983年   5986篇
  1982年   5350篇
  1981年   5613篇
  1980年   5157篇
  1979年   5142篇
  1978年   4993篇
  1977年   5891篇
  1976年   7744篇
  1975年   4300篇
  1974年   4155篇
  1973年   4180篇
  1972年   3429篇
  1971年   3090篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  相似文献   
2.
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   
3.
ABSTRACT

Bacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted.  相似文献   
4.
5.
6.
7.
8.
9.
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   
10.

To increase the efficiency of designing systems intended for monitoring surface cracks in aluminum structures during their working life, we have analyzed a two-dimensional symmetric problem on uniaxial extension of an Al-polyimide-Cu layered structure with ideal adhesion between layers and a model crack in the aluminum base. The problem has been first solved for a sample with the crack modeled by a zero-thickness notch using the ANSYS engineering simulation program package. It is shown that this setting of the problem can lead to inadequate results as manifested, in particular, by significantly overstated mechanical stresses in aluminum in the region of crack emergence on the surface. In order to eliminate this difficulty, we propose to use the structure with a model defect in the form of a notch of nonzero thickness in the initial unstressed state of the structure. Recommendations for selecting the thickness of a notch used in the model structure are given.

  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