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   653005篇
  免费   9878篇
  国内免费   1878篇
电工技术   11397篇
综合类   2842篇
化学工业   95361篇
金属工艺   28542篇
机械仪表   22316篇
建筑科学   15689篇
矿业工程   3348篇
能源动力   16092篇
轻工业   52595篇
水利工程   7071篇
石油天然气   10636篇
武器工业   39篇
无线电   72610篇
一般工业技术   128651篇
冶金工业   112194篇
原子能技术   11441篇
自动化技术   73937篇
  2022年   3303篇
  2021年   5211篇
  2020年   3796篇
  2019年   4891篇
  2018年   25583篇
  2017年   24893篇
  2016年   19690篇
  2015年   6803篇
  2014年   10009篇
  2013年   25312篇
  2012年   19517篇
  2011年   33799篇
  2010年   28267篇
  2009年   27450篇
  2008年   28356篇
  2007年   30211篇
  2006年   15966篇
  2005年   17924篇
  2004年   16108篇
  2003年   15685篇
  2002年   13719篇
  2001年   13086篇
  2000年   12211篇
  1999年   12797篇
  1998年   33765篇
  1997年   23508篇
  1996年   17883篇
  1995年   13259篇
  1994年   11487篇
  1993年   11190篇
  1992年   7983篇
  1991年   7508篇
  1990年   7309篇
  1989年   7064篇
  1988年   6525篇
  1987年   5802篇
  1986年   5699篇
  1985年   6315篇
  1984年   5930篇
  1983年   5198篇
  1982年   4943篇
  1981年   5015篇
  1980年   4745篇
  1979年   4629篇
  1978年   4431篇
  1977年   5406篇
  1976年   7110篇
  1975年   3807篇
  1974年   3562篇
  1973年   3674篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
Metallurgical and Materials Transactions A - The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y...  相似文献   
73.
Hussien  O. S.  Elamy  M. I. 《Strength of Materials》2020,52(3):470-479
Strength of Materials - The use of a damping system is one of the seismic protection systems that improve the seismic response of structures. The proposed methodology estimates the location (which...  相似文献   
74.
Powder Metallurgy and Metal Ceramics - The infiltration of aluminum melts into porous metal skeletons produced by powder metallurgy methods, including 3D printing, under a pressure gradient was...  相似文献   
75.
Measurement Techniques - A method is proposed for transferring the unit of mean power of laser radiation by means of measuring high-intensity power (kilowatts), with the possibility of constant...  相似文献   
76.
Sustainable and efficient food supply chain has become an essential component of one’s life. The model proposed in this paper is deeply linked to people's quality of life as a result of which there is a large incentive to fulfil customer demands through it. This proposed model can enhance food quality by making the best possible food quality accessible to customers, construct a sustainable logistics system considering its environmental impact and ensure the customer demand to be fulfilled as fast as possible. In this paper, an extended model is examined that builds a unified planning problem for efficient food logistics operations where four important objectives are viewed: minimising the total expense of the system, maximising the average food quality along with the minimisation of the amount of CO2 emissions in transportation along with production and total weighted delivery lead time minimisation. A four objective mixed integer linear programming model for intelligent food logistics system is developed in the paper. The optimisation of the formulated mathematical model is proposed using a modified multi-objective particle swarm optimisation algorithm with multiple social structures: MO-GLNPSO (Multi-Objective Global Local Near-Neighbour Particle Swarm Optimisation). Computational results of a case study on a given dataset as well as on multiple small, medium and large-scale datasets followed by sensitivity analysis show the potency and effectiveness of the introduced method. Lastly, there has been a scope for future study displayed which would lead to the further progress of these types of models.  相似文献   
77.
78.
79.
Programming and Computer Software - Image segmentation using a hierarchical sequence of piecewise constant approximations that minimally differ from the original image in terms of the total squared...  相似文献   
80.
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