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   11213篇
  免费   1027篇
  国内免费   13篇
电工技术   87篇
综合类   6篇
化学工业   2770篇
金属工艺   137篇
机械仪表   348篇
建筑科学   510篇
矿业工程   26篇
能源动力   241篇
轻工业   2267篇
水利工程   87篇
石油天然气   21篇
无线电   823篇
一般工业技术   2187篇
冶金工业   767篇
原子能技术   32篇
自动化技术   1944篇
  2024年   39篇
  2023年   162篇
  2022年   139篇
  2021年   378篇
  2020年   324篇
  2019年   314篇
  2018年   449篇
  2017年   460篇
  2016年   567篇
  2015年   481篇
  2014年   621篇
  2013年   1147篇
  2012年   990篇
  2011年   789篇
  2010年   581篇
  2009年   558篇
  2008年   596篇
  2007年   519篇
  2006年   463篇
  2005年   317篇
  2004年   280篇
  2003年   255篇
  2002年   240篇
  2001年   151篇
  2000年   128篇
  1999年   115篇
  1998年   174篇
  1997年   144篇
  1996年   98篇
  1995年   93篇
  1994年   83篇
  1993年   74篇
  1992年   47篇
  1991年   34篇
  1990年   24篇
  1989年   25篇
  1988年   28篇
  1987年   19篇
  1986年   29篇
  1985年   31篇
  1984年   25篇
  1983年   19篇
  1982年   24篇
  1981年   20篇
  1980年   18篇
  1979年   23篇
  1978年   12篇
  1977年   13篇
  1976年   18篇
  1973年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
7.
8.
There are evidence indicating that endoscopic retrograde cholangiopancreatography with sphincterotomy (ERCP+S) reduces the rate of complications in patients with severe acute biliary pancreatitis (ABP). The aim of this study was to analyze our experience in the treatment of severe ABP with ERCP+S and compare the evolution of the patients treated early (3 days or less following admission) with those treated late (after the 3rd day). A retrospective review of the clinical histories of the 16 patients with severe ABP treated with ERCP+S over the last two years is presented, analyzing their clinical features on admission and evolution. Biliary stones or biliary sludge was observed in 11 cases (69%). Nine patients had undergone early, and 7 late, ERCP+S. The patients of the latter group presented a greater number of complications during evolution than the former group (43% vs 0%; p = 0.025). The mortality of the patients of the late ERCP+S was also greater although without statistical significance (28.6% vs 0%; p = 0.15). No complication secondary to ERCP+S was detected. These findings confirm the fact that ERCP+S performed early in severe ABP significantly reduces the number of complications and is associated with a lower mortality.  相似文献   
9.
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   
10.
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   
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