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   1174篇
  免费   80篇
  国内免费   12篇
电工技术   19篇
综合类   5篇
化学工业   277篇
金属工艺   31篇
机械仪表   68篇
建筑科学   43篇
矿业工程   1篇
能源动力   78篇
轻工业   121篇
水利工程   18篇
石油天然气   21篇
无线电   103篇
一般工业技术   215篇
冶金工业   64篇
原子能技术   5篇
自动化技术   197篇
  2024年   5篇
  2023年   23篇
  2022年   20篇
  2021年   74篇
  2020年   68篇
  2019年   86篇
  2018年   107篇
  2017年   81篇
  2016年   85篇
  2015年   38篇
  2014年   70篇
  2013年   136篇
  2012年   67篇
  2011年   83篇
  2010年   49篇
  2009年   51篇
  2008年   27篇
  2007年   20篇
  2006年   10篇
  2005年   13篇
  2004年   5篇
  2003年   12篇
  2002年   7篇
  2001年   4篇
  1999年   3篇
  1998年   8篇
  1997年   7篇
  1996年   3篇
  1995年   4篇
  1994年   6篇
  1993年   4篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1989年   2篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   5篇
  1982年   13篇
  1981年   3篇
  1979年   5篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1973年   2篇
  1970年   5篇
  1966年   6篇
  1961年   3篇
排序方式: 共有1266条查询结果,搜索用时 15 毫秒
31.
Modeling and Management of Firewall Policies   总被引:1,自引:0,他引:1  
Firewalls are core elements in network security. However, managing firewall rules, especially for enterprise networks, has become complex and error-prone. Firewall filtering rules have to be carefully written and organized in order to correctly implement the security policy. In addition, inserting or modifying a filtering rule requires thorough analysis of the relationship between this rule and other rules in order to determine the proper order of this rule and commit the updates. In this paper we present a set of techniques and algorithms that provide automatic discovery of firewall policy anomalies to reveal rule conflicts and potential problems in legacy firewalls, and anomaly-free policy editing for rule insertion, removal, and modification. This is implemented in a user-friendly tool called ?Firewall Policy Advisor.? The Firewall Policy Advisor significantly simplifies the management of any generic firewall policy written as filtering rules, while minimizing network vulnerability due to firewall rule misconfiguration.  相似文献   
32.
This paper considers the no-wait flow shop scheduling problem with due date constraints. In the no-wait flow shop problem, waiting time is not allowed between successive operations of jobs. Moreover, a due date is associated with the completion of each job. The considered objective function is makespan. This problem is proved to be strongly NP-Hard. In this paper, a particle swarm optimisation (PSO) is developed to deal with the problem. Moreover, the effect of some dispatching rules for generating initial solutions are studied. A Taguchi-based design of experience approach has been followed to determine the effect of the different values of the parameters on the performance of the algorithm. To evaluate the performance of the proposed PSO, a large number of benchmark problems are selected from the literature and solved with different due date and penalty settings. Computational results confirm that the proposed PSO is efficient and competitive; the developed framework is able to improve many of the best-known solutions of the test problems available in the literature.  相似文献   
33.
The reaction of 5-arylidene-4-arylimino-2-thiazolidinones 4 with GRIGNARD reagents effected 1,4-addition to the exocyclic  CC bond with the formation of 5 . Alkylation of the arylidene derivatives 4 with diazomethane or methyl iodide results in the formation of the N-methyl derivatives 6 . Treatment of 6 with phenylmagnesium bromide effects addition of the reagent to the double bond of the lateral chain to yield products, proved to have structure 8 . The 5-arylazo derivatives 9 of 4-arylimino-2-thiazolidinones were obtained by coupling 4 with aromatic diazonium chlorides. Compounds 9 were N-methylated with diazomethane to yield 10 .  相似文献   
34.
The flow-induced motion(FIM)of an elastically mounted square-section cylinder is experimentally investigated over a wide range of Reynolds numbers(1.5×104<Re<7....  相似文献   
35.
River water management is challenging not only since they are open systems with changing physical structures, but also because the water values are mostly unknown over varied sectors. If policymakers grasp water values, water management will be more efficient. This research intends to examine the values of water in agriculture, which receives the most substantial portion of water resources, with the values of water in the environment in Isfahan located in the Zayandehrood River basin of Iran. The consequences of contingent valuation and production function methods revealed that per cubic metre value of water is 13 times higher in the environment than agriculture. The government should reconsider the higher value of the environment despite it is a non‐market value. The contingent valuation model additionally proved that women exhibited 21% more willingness to pay than men in order to protect the environment; however, they are paid less by 36%.  相似文献   
36.
37.
38.
International Journal of Control, Automation and Systems - In this paper, an actuator fault tolerant control (FTC) has been designed using dynamic sliding mode control (DSMC) for single input...  相似文献   
39.
The antibacterial activity of Mentha spicata and Mentha aquatica essential oils (EO) was tested against Staphylococcus aureus, Lactobacillus reuteri, Bifidobacterium animalis and Clostridium perfringens using agar well and disc diffusion techniques. Results showed that M. spicata EO had the highest inhibition activity against the studied microorganisms. Then, the antibacterial activity of both EO at 1500 and 2500 ppm was examined in industrial liquid kashk during the storage at 4 °C for 20 days. Both EO reduced the S. aureus viable count below 5 log CFU g?1 after 4 days; however, the population of Cperfringens, L. reuteri and B. animalis decreased <1 log CFU g?1 during the storage time. The least deteriorative effect on the lactic acid bacteria was related to M. aquatica. As revealed by organoleptic studies, kashk samples containing M. aquatica EO at 1500 and 2500 ppm were the most preferred samples.  相似文献   
40.
Bulletin of Engineering Geology and the Environment - The spatial prediction of landslide susceptibility locations is a crucial task to support risk management and development plans in mountainous...  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