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   418篇
  免费   22篇
  国内免费   7篇
电工技术   2篇
综合类   5篇
化学工业   102篇
金属工艺   15篇
机械仪表   3篇
建筑科学   19篇
能源动力   10篇
轻工业   75篇
水利工程   9篇
武器工业   3篇
无线电   18篇
一般工业技术   66篇
冶金工业   54篇
自动化技术   66篇
  2023年   11篇
  2022年   9篇
  2021年   15篇
  2020年   13篇
  2019年   10篇
  2018年   7篇
  2017年   10篇
  2016年   17篇
  2015年   17篇
  2014年   15篇
  2013年   19篇
  2012年   19篇
  2011年   38篇
  2010年   29篇
  2009年   26篇
  2008年   27篇
  2007年   22篇
  2006年   25篇
  2005年   18篇
  2004年   12篇
  2003年   9篇
  2002年   7篇
  2001年   4篇
  2000年   11篇
  1999年   7篇
  1998年   9篇
  1997年   7篇
  1996年   3篇
  1995年   9篇
  1994年   2篇
  1993年   5篇
  1992年   2篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1986年   1篇
  1985年   1篇
  1977年   2篇
  1976年   1篇
  1957年   1篇
排序方式: 共有447条查询结果,搜索用时 187 毫秒
11.
UML在流程工业优化调度工艺描述系统中的应用   总被引:1,自引:0,他引:1  
结合建模工具Rational Rosc说明如何在系统开发过程中运用UML建模。通过流程工业优化调度工艺描述系统的实际建模,对UML建模应用作了进一步说明。  相似文献   
12.
线性最优调节器二阶工程设计法及应用   总被引:1,自引:0,他引:1       下载免费PDF全文
本文利用文[1]结论,给出一种实用线性最优调节器二阶工程设计法.该设计法建立了古典控制意义上的系统性能指标与二次型性能指标的关系.并给出解析其式,提出二阶最优参数域的概念.通过轧机综合最优控制系统的设计和实验,验证了该方法在工程设计中的可行性.  相似文献   
13.

Definition of the problem

“Medical necessity” (MedN) is the central regulatory concept for decisions about which services are covered by German statutory health insurance. Despite its seeming objectivity and dependence on physicians’ expert judgment, the concept is by no means clearly defined.

Arguments

In this first of five planned papers on the conceptual analysis of MedN from the perspectives of philosophy and ethics of medicine, law, and (social) medicine, the focus lies on systemizing ongoing controversies.

Conclusion

Our goal is to come up with a so far missing foundation for detailed debates. We aim to clarify MedN’s conceptual structure, function, contextuality, and ambiguities as well as the fundamental limits of conceptual investigations for the normative questions at issue of regulating medical services.
  相似文献   
14.
15.
This paper presents the results of a survey of the livelihoods of people living in the eastern part of the subtropical plains of Nepal, known as the terai. Both qualitative and quantitative approaches were used in the survey and further data were obtained through focus group discussions, in-depth interviews with key informants and participant observations. Changes were recorded both in the perception of agricultural and residential land for a secure living and the meaning given to food security. The principal drivers causing these changes were voluntary out-migration for remunerative employment, urbanization and the reluctance of members of the younger generation to farm, which they regard as a “dirty job”. In consequence, people’s livelihood practices and access to food are gradually shifting from an agriculture-based economy to an economy that is based on other sources of income, including remittances from out-migrants. This development threatens not only the role of agriculture in rural livelihoods but also the food security of the country.  相似文献   
16.
Argon belongs to the group of noble gases, which are regarded as chemically inert. Astonishingly some of these gases exert biological properties and during the last decades more and more reports demonstrated neuroprotective and organoprotective effects. Recent studies predominately use in vivo or in vitro models for ischemic pathologies to investigate the effect of argon treatment. Promising data has been published concerning pathologies like cerebral ischemia, traumatic brain injury and hypoxic ischemic encephalopathy. However, models applied and administration of the therapeutic gas vary. Here we provide a systematic review to summarize the available data on argon’s neuro- and organoprotective effects and discuss its possible mechanism of action. We aim to provide a summary to allow further studies with a more homogeneous setting to investigate possible clinical applications of argon.  相似文献   
17.
The Al-rich part of the Fe-Al phase diagram between 50 and 80 at.% Al including the complex intermetallic phases Fe5Al8 (ε), FeAl2, Fe2Al5, and Fe4Al13 was re-investigated in detail. A series of 19 alloys was produced and heat-treated at temperatures in the range from 600 to 1100 °C for up to 5000 h. The obtained data were further complemented by results from a number of diffusion couples, which helped to determine the homogeneity ranges of the phases FeAl2, Fe2Al5, and Fe4Al13. All microstructures were inspected by scanning electron microscopy (SEM), and chemical compositions of the equilibrium phases as well as of the alloys were obtained by electron probe microanalysis (EPMA). Crystal structures and the variation of the lattice parameters were studied by x-ray diffraction (XRD) and differential thermal analysis (DTA) was applied to measure all types of transition temperatures. From these results, a revised version of the Al-rich part of the phase diagram was constructed.  相似文献   
18.
19.
Recently, a number of advanced architecture machines have become commercially available. These new machines promise better cost performance than traditional computers, and some of them have the potential of competing with current supercomputers, such as the CRAY X-MP, in terms of maximum performance. This paper describes the methodology and results of a pilot study of the performance of a broad range of advanced architecture computers using a number of complete scientific application programs. The computers evaluated include:
  • 1 shared-memory bus architecture machines such as the Alliant FX/8, the Encore Multimax, and the Sequent Balance and Symmetry
  • 2 shared-memory network-connected machines such as the Butterfly
  • 3 distributed-memory machines such as the NCUBE, Intel and Jet Propulsion Laboratory (JPL)/Caltech hypercubes
  • 4 very long instruction word machines such as the Cydrome Cydra-5
  • 5 SIMD machines such as the Connection Machine
  • 6 ‘traditional’ supercomputers such as the CRAY X-MP, CRAY-2 and SCS-40.
Seven application codes from a number of scientific disciplines have been used in the study, although not all the codes were run on every machine. The methodology and guidelines for establishing a standard set of benchmark programs for advanced architecture computers are discussed. The CRAYs offer the best performance on the benchmark suite; the shared memory multiprocessor machines generally permitted some parallelism, and when coupled with substantial floating point capabilities (as in the Alliant FX/8 and Sequent Symmetry), provided an order of magnitude less speed than the CRAYs. Likewise, the early generation hypercubes studied here generally ran slower than the CRAYs, but permitted substantial parallelism from each of the application codes.  相似文献   
20.
Drug‐resistant Pseudomonas aeruginosa (PA) strains are on the rise, making treatment with current antibiotics ineffective. Hence, circumventing resistance or restoring the activity of antibiotics by novel approaches is of high demand. Targeting the Pseudomonas quinolone signal quorum sensing (PQS‐QS) system is an intriguing strategy to abolish PA pathogenicity without affecting the viability of the pathogen. Herein we report the structure–activity relationships of 2‐sulfonylpyrimidines, which were previously identified as dual‐target inhibitors of the PQS receptor PqsR and the PQS synthase PqsD. The SAR elucidation was guided by a combined approach using ligand efficiency and ligand lipophilicity efficiency to select the most promising compounds. In addition, the most effective inhibitors were rationally modified by the guidance of QSAR using Hansch analyses. Finally, these inhibitors showed the capacity to decrease biofilm mass and extracellular DNA, which are important determinants for antibiotic resistance.  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