首页 | 官方网站   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   643517篇
  免费   9234篇
  国内免费   1918篇
工业技术   654669篇
  2021年   4701篇
  2019年   4329篇
  2018年   6977篇
  2017年   6880篇
  2016年   7321篇
  2015年   5749篇
  2014年   9442篇
  2013年   30681篇
  2012年   16170篇
  2011年   22492篇
  2010年   17439篇
  2009年   19813篇
  2008年   21069篇
  2007年   21163篇
  2006年   18980篇
  2005年   17481篇
  2004年   17004篇
  2003年   16555篇
  2002年   16035篇
  2001年   16126篇
  2000年   15179篇
  1999年   16075篇
  1998年   37322篇
  1997年   27102篇
  1996年   21362篇
  1995年   16617篇
  1994年   14980篇
  1993年   14359篇
  1992年   10730篇
  1991年   10318篇
  1990年   9847篇
  1989年   9489篇
  1988年   9144篇
  1987年   7675篇
  1986年   7772篇
  1985年   9286篇
  1984年   8576篇
  1983年   7734篇
  1982年   7143篇
  1981年   7207篇
  1980年   6771篇
  1979年   6539篇
  1978年   6103篇
  1977年   7418篇
  1976年   9892篇
  1975年   5231篇
  1974年   5012篇
  1973年   4932篇
  1972年   3974篇
  1971年   3493篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
The proliferating need for sustainability intervention in food grain transportation planning is anchoring the attention of researchers in the interests of stakeholders and environment at large. Uncertainty associated with food grain supply further intensifies the problem steering the need for designing robust, cost-efficient and sustainable models. In line with this, this paper aims to develop a robust and sustainable intermodal transportation model to facilitate single type of food grain commodity shipments while considering procurement uncertainty, greenhouse gas emissions, and intentional hub disruption. The problem is designed as a mixed integer non-linear robust optimisation model on a hub and spoke network for evaluating near optimal shipment quantity, route selection and hub location decisions. The robust optimisation approach considers minimisation of total relative regret associated with total cost subject to several real-time constraints. A version of Particle Swarm Optimisation with Differential Evolution is proposed to tackle the resulting NP-hard problem. The model is tested with two other state-of the art meta-heuristics for small, medium, and large datasets subject to different procurement scenarios inspired from real time food grain operations in Indian context. Finally, the solution is evaluated with respect to total cost, model and solution robustness for all instances.  相似文献   
2.
3.
4.
5.
6.
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   
7.
8.
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications.  相似文献   
9.
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-23

京公网安备 11010802026262号