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   39443篇
  免费   2358篇
  国内免费   322篇
电工技术   637篇
综合类   368篇
化学工业   7608篇
金属工艺   1051篇
机械仪表   1014篇
建筑科学   1214篇
矿业工程   226篇
能源动力   794篇
轻工业   6209篇
水利工程   410篇
石油天然气   237篇
武器工业   88篇
无线电   1557篇
一般工业技术   6087篇
冶金工业   9268篇
原子能技术   214篇
自动化技术   5141篇
  2024年   115篇
  2023年   360篇
  2022年   545篇
  2021年   1026篇
  2020年   837篇
  2019年   925篇
  2018年   1432篇
  2017年   1426篇
  2016年   1476篇
  2015年   1194篇
  2014年   1461篇
  2013年   2932篇
  2012年   2359篇
  2011年   2246篇
  2010年   1854篇
  2009年   1680篇
  2008年   1643篇
  2007年   1542篇
  2006年   1111篇
  2005年   935篇
  2004年   827篇
  2003年   708篇
  2002年   668篇
  2001年   524篇
  2000年   473篇
  1999年   532篇
  1998年   2741篇
  1997年   1845篇
  1996年   1202篇
  1995年   728篇
  1994年   561篇
  1993年   626篇
  1992年   215篇
  1991年   219篇
  1990年   171篇
  1989年   173篇
  1988年   171篇
  1987年   144篇
  1986年   125篇
  1985年   148篇
  1984年   127篇
  1983年   94篇
  1982年   137篇
  1981年   151篇
  1980年   160篇
  1979年   78篇
  1978年   80篇
  1977年   326篇
  1976年   706篇
  1973年   65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.
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   
4.
5.
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   
6.
7.
8.
9.
10.
ABSTRACT

In this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory.  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