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   33927篇
  免费   1929篇
  国内免费   29篇
电工技术   228篇
综合类   18篇
化学工业   6453篇
金属工艺   607篇
机械仪表   682篇
建筑科学   906篇
矿业工程   71篇
能源动力   540篇
轻工业   5403篇
水利工程   311篇
石油天然气   118篇
武器工业   5篇
无线电   1204篇
一般工业技术   5521篇
冶金工业   9307篇
原子能技术   116篇
自动化技术   4395篇
  2024年   77篇
  2023年   286篇
  2022年   294篇
  2021年   745篇
  2020年   652篇
  2019年   737篇
  2018年   1332篇
  2017年   1298篇
  2016年   1345篇
  2015年   1033篇
  2014年   1206篇
  2013年   2550篇
  2012年   1902篇
  2011年   1701篇
  2010年   1413篇
  2009年   1256篇
  2008年   1224篇
  2007年   1158篇
  2006年   765篇
  2005年   664篇
  2004年   625篇
  2003年   565篇
  2002年   547篇
  2001年   403篇
  2000年   379篇
  1999年   472篇
  1998年   2815篇
  1997年   1872篇
  1996年   1184篇
  1995年   692篇
  1994年   535篇
  1993年   632篇
  1992年   206篇
  1991年   222篇
  1990年   161篇
  1989年   175篇
  1988年   180篇
  1987年   161篇
  1986年   132篇
  1985年   155篇
  1984年   125篇
  1983年   95篇
  1982年   130篇
  1981年   147篇
  1980年   158篇
  1979年   77篇
  1978年   81篇
  1977年   299篇
  1976年   664篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 10 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