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   304610篇
  免费   6441篇
  国内免费   1295篇
电工技术   5270篇
综合类   301篇
化学工业   46954篇
金属工艺   11959篇
机械仪表   8245篇
建筑科学   8116篇
矿业工程   600篇
能源动力   7443篇
轻工业   32682篇
水利工程   2423篇
石油天然气   1589篇
武器工业   8篇
无线电   34001篇
一般工业技术   55520篇
冶金工业   65481篇
原子能技术   4127篇
自动化技术   27627篇
  2021年   2902篇
  2020年   2197篇
  2019年   2606篇
  2018年   4638篇
  2017年   4498篇
  2016年   4855篇
  2015年   3667篇
  2014年   5362篇
  2013年   15233篇
  2012年   9010篇
  2011年   11079篇
  2010年   8939篇
  2009年   9325篇
  2008年   10109篇
  2007年   9965篇
  2006年   8701篇
  2005年   7908篇
  2004年   7533篇
  2003年   7412篇
  2002年   7301篇
  2001年   7084篇
  2000年   6522篇
  1999年   7298篇
  1998年   21216篇
  1997年   14596篇
  1996年   10845篇
  1995年   7849篇
  1994年   6851篇
  1993年   6732篇
  1992年   4405篇
  1991年   4362篇
  1990年   3896篇
  1989年   3817篇
  1988年   3732篇
  1987年   3156篇
  1986年   3096篇
  1985年   3710篇
  1984年   3315篇
  1983年   2929篇
  1982年   2796篇
  1981年   2842篇
  1980年   2691篇
  1979年   2441篇
  1978年   2407篇
  1977年   3233篇
  1976年   5057篇
  1975年   2020篇
  1974年   1896篇
  1973年   1897篇
  1972年   1526篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
3.
4.
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.  相似文献   
5.
6.
7.
8.
9.
10.
This study deals with the formulation of natural drugs into hydrogels. For the first time, compounds from the sage essential oil were formulated into chitosan hydrogels. A sample preparation procedure for hydrophobic volatile analytes present in a hydrophilic water matrix along with an analytical method based on the gas chromatography coupled with the mass spectrometry (GC-MS) was developed and applied for the evaluation of the identity and quantity of essential oil components in the hydrogels and saline samples. The experimental results revealed that the chitosan hydrogels are suitable for the formulation of sage essential oil. The monoterpene release can be effectively controlled by both chitosan and caffeine concentration in the hydrogels. Permeation experiment, based on a hydrogel with the optimized composition [3.5% (w/w) sage essential oil, 2.0% (w/w) caffeine, 2.5% (w/w) chitosan and 0.1% (w/w) Tween-80] in donor compartment, saline solution in acceptor compartment, and semi-permeable cellophane membrane, demonstrated the useful permeation selectivity. Here, (according to lipophilicity) an enhanced permeation of the bicyclic monoterpenes with antiflogistic and antiseptic properties (eucalyptol, camphor and borneol) and, at the same time, suppressed permeation of toxic thujone (not exceeding its permitted applicable concentration) was observed. These properties highlight the pharmaceutical importance of the developed chitosan hydrogel formulating sage essential oil in the dermal applications.  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