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   750篇
  免费   8篇
  国内免费   2篇
化学工业   48篇
机械仪表   3篇
建筑科学   2篇
矿业工程   2篇
能源动力   5篇
轻工业   19篇
水利工程   9篇
无线电   5篇
一般工业技术   14篇
冶金工业   632篇
原子能技术   1篇
自动化技术   20篇
  2024年   1篇
  2023年   2篇
  2022年   4篇
  2021年   6篇
  2020年   3篇
  2019年   5篇
  2018年   10篇
  2017年   5篇
  2016年   10篇
  2015年   5篇
  2014年   4篇
  2013年   13篇
  2012年   15篇
  2011年   4篇
  2010年   3篇
  2009年   8篇
  2008年   5篇
  2007年   3篇
  2006年   1篇
  2005年   2篇
  2004年   4篇
  2003年   2篇
  2001年   1篇
  2000年   4篇
  1999年   19篇
  1998年   171篇
  1997年   109篇
  1996年   68篇
  1995年   52篇
  1994年   29篇
  1993年   38篇
  1992年   4篇
  1991年   5篇
  1990年   7篇
  1989年   7篇
  1988年   5篇
  1987年   5篇
  1986年   6篇
  1985年   4篇
  1982年   6篇
  1981年   9篇
  1980年   7篇
  1979年   1篇
  1978年   1篇
  1977年   21篇
  1976年   63篇
  1975年   3篇
排序方式: 共有760条查询结果,搜索用时 15 毫秒
51.
52.
53.
The accurate prediction of cost profiles of future job tasks on the nodes of clusters or grids helps users to select the cost performance profile that best suits their budgets. The current software designed to deploy job tasks uses forecasts of the target computers' future load profiles. Once the job task's future load profile is known, converting it to its cost profile needs further analysis as the cost depends on other factors such as its delays and variable background loads. This paper introduces a new charging mechanism for charging future job tasks, called the Cost Profiling Model. The model has been implemented in a Software Framework and evaluated for its prediction accuracy. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
54.
Most developing countries include rural electrification programs in their efforts to improve social conditions. There are, however, several obstacles to the evaluation of such programs and therefore of their social, economic, environmental and energy impacts on the target population, particularly on impoverished communities located in remote areas. Evaluation of the efficacy of public policies aimed at rural electrification in South Africa, China, India and Brazil enables such actions to be quantified and re-considered so as to bolster the sustainability of their planning and implementation and also so as to enable comprehension of the significance of access to electricity in relation to other aspects of the drive to improve living standards. The provision of electric energy amounts to more than access to a public service and should be considered an essential right, in a context of social equity and justice, which permits social integration and the access to other equally essential services.  相似文献   
55.
This work investigated the pH, titratable acidity and total solids of the cassava starch fermentation water, using the traditional method and a method modified through the addition of glucose. Sour cassava starch production controlled by the characteristic of the fermentation water produced the best product (biscuit specific volume of 7.66 ± 0.41 mL g?1) at 33th day of fermentation in the modified method and at 85th day (biscuit specific volume of 6.53 ± 0.59 mL g?1) in traditional method. But, comparatively to the commercial sour cassava starch (biscuit specific volume of 3.48 ± 0.12 mL g?1), both traditional and modified methods, controlled by titratable acidity of fermentation water, can be retired from the fermentation tank in the 19th and 32th day of fermentation, with biscuit specific volume of 4.75 ± 0.30 and 5.17 ± 0.46 mL g?1, respectively. Determining fermentation time can help to standardise sour cassava starch and to promote future applications of the fermentation water as a raw material.  相似文献   
56.
OBJECTIVE: Cholelithiasis is a common problem in hospitals of the Peruvian Andes; however, its prevalence in Andean communities is unknown. To estimate the prevalence of gallstone disease in this locale, we conducted a cross-sectional community study in three high-altitude Peruvian rural villages (i.e., > 3000 m above sea level). METHODS: We examined 911 volunteers > 15 yr of age from three villages for gallstone disease by history and ultrasonography. Risk factors for gallstone disease were examined in 382 volunteers from one village. RESULTS: The age-adjusted prevalence of gallstone disease ranged from 4-10% in men and from 18-20% in women. Women had significantly higher age-adjusted prevalence rates than did men. The prevalence of gallstone disease increased significantly with age and decreased significantly with alcohol consumption. Although not statistically significant, we found a positive association between gallstone disease and body mass index. CONCLUSION: The results of this study indicate that gallstone disease, commonly perceived as a disease of the developed world, is also a common problem in high-altitude Peruvian communities.  相似文献   
57.
Synucleins constitute a group of unique, evolutionarily conserved proteins that are expressed predominantly in neurons of the central and peripheral nervous system. Although the normal cellular functions of synucleins are not clear, these proteins have been implicated in various neurodegenerative conditions in humans. We found that persyn, a recently characterized member of the synuclein family, is expressed not only in the nervous system but also in the stratum granulosum of the epidermis of neonatal and adult mice. This finding together with our recent observations that persyn influences neurofilament network integrity in sensory neurons raises the possibility that persyn in skin could be involved in modulation of the keratin network.  相似文献   
58.
Species-specific nested PCR was used to detect Treponema amylovorum, Treponema denticola, Treponema maltophilum, Treponema medium, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii in dental plaque. Subjects with periodontitis harbored all species, but T. pectinovorum and T. vincentii were not found in plaque from disease-free subjects.  相似文献   
59.
60.
As the genetic and physical mapping stage of the Human Genome Project nears completion, the focus is shifting toward the development of technologies for high-throughput analysis of gene function. Whereas DNA sequencing will enable the assignment of presumed function to a large number of genes in mice and humans, it is clear that the great majority of genes will have to be evaluated in vivo to accurately assess their role in a complex organism. While gene targeting in mouse embryonic stem (ES) cells is the current method of choice for the characterization of gene function in mice, it remains relatively labor intensive and lacks the throughput required for analysis of genome function on a large scale. Alternative methods of efficient mutagenesis will clearly be required for this task. Chromosomal deletions are powerful tools in the genetic analysis of complex genomes, enabling the systematic identification and localization of functional units along defined chromosomal regions. Not only are deletions useful for the identification of genetic functions, but they serve as mapping reagents for existing mutations or traits. While their use has been an essential tool in Drosophila genetics, classical mutagenesis in mice has been logistically impractical for generating deletions. We have previously described an efficient method for generating radiation-induced deletion complexes at defined regions in the genome using ES cells. In this article, we detail the methodological aspects of this technology and describe the applications of chromosomal deletions for characterizing gene function in ways that make optimal use of the information generated by the first stage of the Genome Project.  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