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   11868篇
  免费   1000篇
  国内免费   14篇
电工技术   98篇
综合类   8篇
化学工业   3017篇
金属工艺   136篇
机械仪表   353篇
建筑科学   554篇
矿业工程   23篇
能源动力   277篇
轻工业   2355篇
水利工程   111篇
石油天然气   29篇
无线电   888篇
一般工业技术   2220篇
冶金工业   553篇
原子能技术   27篇
自动化技术   2233篇
  2024年   37篇
  2023年   166篇
  2022年   175篇
  2021年   412篇
  2020年   341篇
  2019年   336篇
  2018年   506篇
  2017年   510篇
  2016年   613篇
  2015年   483篇
  2014年   625篇
  2013年   1131篇
  2012年   1084篇
  2011年   992篇
  2010年   634篇
  2009年   591篇
  2008年   662篇
  2007年   599篇
  2006年   462篇
  2005年   345篇
  2004年   319篇
  2003年   270篇
  2002年   250篇
  2001年   141篇
  2000年   146篇
  1999年   97篇
  1998年   93篇
  1997年   98篇
  1996年   72篇
  1995年   66篇
  1994年   70篇
  1993年   55篇
  1992年   41篇
  1991年   31篇
  1990年   23篇
  1989年   25篇
  1988年   24篇
  1987年   13篇
  1986年   19篇
  1985年   32篇
  1984年   28篇
  1983年   21篇
  1982年   22篇
  1981年   25篇
  1980年   17篇
  1979年   26篇
  1978年   13篇
  1976年   11篇
  1973年   11篇
  1947年   9篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
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   
2.
3.
4.
5.
6.
Summary 2-Furyl vinyl ketone was polymerised using anionic, cationic and free-radical initiators. Yields and molecular weights varied with the type of activation. Whereas radical polymerisation gave a product possessing a regular vinylic structure, other kinds of units were detected in the polymers prepared with anionic and cationic catalysts.  相似文献   
7.
We compare two link analysis ranking methods of web pages in a site. The first, called Site Rank, is an adaptation of PageRank to the granularity of a web site and the second, called Popularity Rank, is based on the frequencies of user clicks on the outlinks in a page that are captured by navigation sessions of users through the web site. We ran experiments on artificially created web sites of different sizes and on two real data sets, employing the relative entropy to compare the distributions of the two ranking methods. For the real data sets we also employ a nonparametric measure, called Spearman's footrule, which we use to compare the top-ten web pages ranked by the two methods. Our main result is that the distributions of the Popularity Rank and Site Rank are surprisingly close to each other, implying that the topology of a web site is very instrumental in guiding users through the site. Thus, in practice, the Site Rank provides a reasonable first order approximation of the aggregate behaviour of users within a web site given by the Popularity Rank.  相似文献   
8.
The interactions of the antihistaminic drug chlorpheniramine maleate (CPM) with the negatively charged polyelectrolytes poly(sodium 4-styrenesulfonate) (PSS) and poly(acrylic acid) (PAA) are studied by the washing method of the diafiltration technique at conditions simulating those of the small intestine such as pH 7.5 and 0.13 M NaCl. The results are compared with those already reported involving other pharmacologically important polyelectrolytes such as alginic acid (ALG), carboxymethylcellulose (CMC), and κ- and ι-carrageenan (κ- and ι-CAR). As in the case of ALG, CMC, and CAR, interactions of CPM with PAA appear to be electrostatic and are cleaved in the presence of 0.13 M NaCl. On the contrary, apart from electrostatic interactions, additional interactions are found with PSS and residual interactions are kept in the presence of 0.13 M NaCl, a fact that may be attributed to π-π interactions and hydrophobic forces. The effect of the addition of 4 M urea, branched poly(ethyleneimine) (BPEI), and poly(vinylpyrrolidone) (PVP) is also studied. The addition of urea 4 M or 0.001 M BPEI produces a decrease on the amounts of counterions bound to PSS at infinite elution, while the addition of PVP does not produce any change on the diafiltration profiles.  相似文献   
9.
This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs.  相似文献   
10.
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