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   480篇
  免费   24篇
  国内免费   4篇
工业技术   508篇
  2023年   7篇
  2022年   13篇
  2021年   16篇
  2020年   9篇
  2019年   5篇
  2018年   5篇
  2017年   15篇
  2016年   20篇
  2015年   20篇
  2014年   36篇
  2013年   26篇
  2012年   37篇
  2011年   46篇
  2010年   30篇
  2009年   29篇
  2008年   24篇
  2007年   26篇
  2006年   26篇
  2005年   22篇
  2004年   12篇
  2003年   8篇
  2002年   15篇
  2001年   7篇
  2000年   10篇
  1999年   7篇
  1998年   3篇
  1997年   4篇
  1996年   5篇
  1995年   4篇
  1994年   2篇
  1993年   3篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
  1973年   1篇
  1965年   1篇
排序方式: 共有508条查询结果,搜索用时 0 毫秒
1.
The use of fiber-reinforced polymer (FRP) composites for strengthening and/or rehabilitation of concrete structures is gaining increasing popularity in the civil engineering community. One of the most attractive applications of FRP materials is their use as confining devices for concrete columns, which may result in remarkable increases of strength and ductility as indicated by numerous published experimental results. Despite a large research effort, a proper analytical tool to predict the behavior of FRP-confined concrete has not yet been established. Most of the available models are empirical in nature and have been calibrated against their own sets of experimental data. On the other hand, the experimental results available in the literature encompass a wide range of values of the significant variables. The objective of this work is a systematic assessment of the performance of the existing models on confinement of concrete columns with FRP materials. The study is conducted in the following steps: the experimental data on confinement of concrete cylinders with FRP available in the technical literature are classified according to the values of the significant variables; the existing empirical and analytical models are reviewed, pointing out their distinct features; the whole set of available experimental results is compared with the whole set of analytical models; and strengths and weaknesses of the various models are analyzed. Finally, a new equation is proposed to evaluate the axial strain at peak stress of FRP-confined concrete cylinders.  相似文献   
2.
本文基于新疆2001—2013年科学与实验研究投入数据的统计,并且对新疆与全国的科研经费、科研投入强度、科研产出等方面进行差异比较分析,发现新疆科研投入存在的不足和问题,最后在此基础上提出拓展经费融资渠道、加大政府科研投入力度、保护科研人员知识产权等相关政策建议。  相似文献   
3.
Coxiella burnetii, the causative agent of Q fever, is an intracellular bacterium and a potential weapon for bioterrorism. The widespread throughout the world, zoonosis is manifested clinically as a self-limited febrile illness, as pneumonia (acute Q fever) or as a chronic illness with endocarditis being its major complication. The recent Netherlands Q fever outbreak has driven the bacterium from a relatively cryptic, underappreciated, “niche” microorganism on the sideline of bacteriology, to one of possibly great impact on public health. Advances in the study of this microorganism proceeded slowly, primarily due to the, until recently, obligatory intracellular nature of the pathogen that in its virulent phase I must be manipulated under biosafety level-3 conditions. Proteomic studies, in particular, have generated a vast amount of information concerning several aspects of the bacterium such as virulence factors, detection/diagnostic and immunogenic biomarkers, inter-/intraspecies variation, resistance to antibiotics, and secreted effector proteins with significant clinical impact. The phenomenon observed following the genomics era, that of generation and accumulation of huge amount of data that ultimately end up unexploited on several databases, begins to emerge in the proteomics field as well. This review will focus on the advances in the field of C. burnetii proteomics through MS, attempting in parallel to utilize some of the proteomics findings by suggesting future directions for the improvement of Q fever diagnosis and therapy.  相似文献   
4.
5.
吴晨  韦向峰 《计算机科学》2016,43(Z6):435-439
在互联网上用户评价内容中很多比较句的比较结果反映了语句陈述者对比较对象的倾向性态度。根据已有的10类比较句句型总结了它们的常见概念搭配,在基于语义块的语句倾向性分析方法的基础上构建了比较句自动识别系统和比较句倾向性自动分析系统。采用第四届中文倾向性分析评测的语料进行实验,对语料中的比较句进行了识别,对比较句中的要素进行了抽取并且分析了比较句的倾向性,识别结果和倾向性分析结果均好于所有参评系统的平均值。  相似文献   
6.
The purpose of the present study was to examine the prevalence of cyber-bullying through Facebook in a sample of 226 Greek university undergraduates, and to explore whether big five personality characteristics, narcissism, as well as attitudes toward Facebook, technological knowledge and skills were predictive of such behavior. Participants completed a self-report questionnaire measuring the above constructs. Results indicated that almost one third of the sample reported Facebook bullying engagement at least once during the past month, with male students reporting more frequent involvement than females. Bullying through Facebook was predicted by low Agreeableness and more time spent on Facebook only for males, whereas for females none of the studied variables predicted engagement in Facebook bullying. Findings are discussed in terms of prevention and intervention strategies.  相似文献   
7.
Orthologs are genes in different species that have diverged from a common ancestral gene after speciation. In contrast, paralogs are genes that have diverged after a gene duplication event. For many comparative analyses, it is of interest to identify orthologs with similar functions. Such orthologs tend to support species divergence (ssd-orthologs) in the sense that they have diverged only due to speciation, to the same relative degree as their species. However, due to incomplete sequencing or gene loss in a species, predicted orthologs can sometimes be paralogs or other non-ssd-orthologs. To increase the specificity of ssd-ortholog prediction, Fulton et al. [Fulton, D., Li, Y., Laird, M., Horsman, B., Roche, F., Brinkman, F., 2006. Improving the specificity of high-throughput ortholog prediction. BMC Bioinformatics 7 (1), 270] developed Ortholuge, a bioinformatics tool that identifies predicted orthologs with atypical genetic divergence. However, when the initial list of putative orthologs contains a non-negligible number of non-ssd-orthologs, the cut-off values that Ortholuge generates for orthology classification are difficult to interpret and can be too high, leading to decreased specificity of ssd-ortholog prediction. Therefore, we propose a complementary statistical approach to determining cut-off values. A benefit of the proposed approach is that it gives the user an estimated conditional probability that a predicted ortholog pair is unusually diverged. This enables the interpretation and selection of cut-off values based on a direct measure of the relative composition of ssd-orthologs versus non-ssd-orthologs. In a simulation comparison of the two approaches, we find that the statistical approach provides more stable cut-off values and improves the specificity of ssd-ortholog prediction for low-quality data sets of predicted orthologs.  相似文献   
8.
本文在总结前人相关研究成果的基础之上,运用线性加权综合法详细测度和对比分析了广西桂林和北海两个旅游目的地品牌竞争力状况,找出桂林和北海旅游目的地品牌竞争力的影响因素,最后提出了桂林和北海旅游目的地品牌竞争力提升策略。  相似文献   
9.
英美国家开展大学生创业教育的历史较早,有许多成功经验。文章探讨了英美高校创业教育在专业设置、培养方案、师资队伍建设、实践环节等方面的实践,比较了中外大学生创业教育中的差距,指出了中国高校创业教育存在的问题,希望能为国内开展创业教育提供思路。  相似文献   
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