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   1111篇
  免费   46篇
  国内免费   28篇
电工技术   35篇
综合类   132篇
化学工业   49篇
金属工艺   27篇
机械仪表   43篇
建筑科学   92篇
矿业工程   17篇
能源动力   27篇
轻工业   52篇
水利工程   28篇
石油天然气   15篇
武器工业   8篇
无线电   40篇
一般工业技术   46篇
冶金工业   374篇
原子能技术   10篇
自动化技术   190篇
  2024年   3篇
  2023年   21篇
  2022年   11篇
  2021年   12篇
  2020年   18篇
  2019年   10篇
  2018年   9篇
  2017年   14篇
  2016年   16篇
  2015年   15篇
  2014年   41篇
  2013年   53篇
  2012年   41篇
  2011年   85篇
  2010年   80篇
  2009年   63篇
  2008年   71篇
  2007年   72篇
  2006年   73篇
  2005年   79篇
  2004年   58篇
  2003年   69篇
  2002年   62篇
  2001年   49篇
  2000年   23篇
  1999年   12篇
  1998年   18篇
  1997年   9篇
  1996年   8篇
  1995年   11篇
  1994年   7篇
  1993年   8篇
  1992年   5篇
  1991年   3篇
  1990年   3篇
  1989年   7篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1985年   2篇
  1983年   2篇
  1982年   3篇
  1981年   4篇
  1979年   2篇
  1978年   3篇
  1976年   3篇
  1964年   3篇
  1958年   1篇
  1957年   2篇
  1955年   1篇
排序方式: 共有1185条查询结果,搜索用时 15 毫秒
51.
Simflowny is a software platform which aims to formalize the main elements of a simulation flow. It allows users to manage (i) formal representations of physical models based on Initial Value Problems (hyperbolic, parabolic and mixed-type partial differential equations), (ii) simulation problems based on such models, and (iii) discretization schemes to translate the problem to a finite mesh. Additionally, Simflowny generates automatically code for general-purpose simulation frameworks. This paper first presents an introductory example of such problems. Then, formal representations are explained. Afterwards, it summarizes the platform’s architecture. Finally, validation results are provided.  相似文献   
52.
唐匡政 《城市建筑》2014,(18):95-96
本文从实用性的角度出发,对性能化设计步骤做了重新整理,归纳。以方便大家进一步理解抗震性能化设计,增强实际设计过程的可操作性。  相似文献   
53.
Three versions of Japanese Evaluated Nuclear Data Library (JENDL) are briefly explained. The first version, JENDL-1, was made aiming mainly at application to fast reactors. The second version, JENDL-2, was built as a bigger general purpose evaluated nuclear data library. It stores nuclear data for 181 nuclides. It has, however, some drawbacks particularly for fusion neutronics calculation. To remove these drawbacks of JENDL-2 and further extend its applicability, the third version, JENDL-3, has now been made. JENDL-3 includes photon-production data for some nuclides, in addition to the data contained in JENDL-2.  相似文献   
54.
工程项目二次创效,是指在保证满足工程质量、工期等合同约定的前提下,通过加强对工程项目施工过程有组织、有系统的进行预测、计划、控制、核算、分析、考核等科学管理活动,以达到强化经营管理、降低工程成本、实现目标利润、创造良好经济效益之目的。  相似文献   
55.
Special purpose machine tools (SPMs) are primarily used for performing drilling-related operations and are widely used in mass production including automotive component manufacturing. Utilization of SPM is considerably widespread; however, this technology is relatively new and expensive. The important problems facing manufacturing industries wishing to utilize this technology is feasibility analysis to decide whether a SPM can be utilised for production of the given part and if it is feasible which SPM components would be appropriate. Since the cost of utilizing SPM is high, feasibility analysis must be performed before any investment on detailed design. This paper proposes a technical feasibility analysis method which assists in deciding whether SPM is applicable for machining a given part to achieve the highest productivity. The method is based on the framework which consists of relations between the desired part properties to the characteristics of the SPM components. These relations are captured as rules and constraints in an intelligent system which is implemented in Visual Basic. Applying the proposed method to a number of industrial parts shows that it is a very useful tool in deciding when SPMs should be utilized.  相似文献   
56.
Two longitudinal studies examined the associations between interpersonal goals (i.e., self-image and compassionate goals) and anxiety and dysphoria (i.e., distress). In Study 1, 199 college freshmen (122 women, 77 men) completed 12 surveys over 12 weeks. Compassionate goals predicted decreased distress, and self-image goals predicted increased distress from pretest to posttest when distress was assessed as anxiety, dysphoria, or a composite, and when the goals were worded as approach goals, avoidance goals, or a composite. In Study 2, 115 first-semester roommate pairs (86 female and 29 male pairs) completed 12 surveys over 12 weeks. Compassionate and self-image goals predicted distress in same-week, lagged-week, and pretest-to-posttest analyses; effects of compassionate goals remained significant when the authors controlled for several known risk factors. Having clear goals consistently explained the association between compassionate goals but not self-image goals and distress. Results supported a path model in which compassionate goals predict increased support given to roommates, which predicts decreased distress. Results also supported a reciprocal association; chronic distress predicted decreased compassionate and increased self-image goals from pretest to posttest, and weekly distress predicted decreased compassionate goals the subsequent week. The results suggest that compassionate goals contribute to decreased distress because they provide meaning and increase support given to others. Distress, in turn, predicts change in goals, creating the potential for upward and downward spirals of goals and distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
57.
The authors examined the degree to which workers were engaging in financial, health, interpersonal/leisure, and work planning for retirement, exploring whether demographic and psychological variables inhibited or promoted planning in each of these domains. Planning in each domain was influenced by a unique set of variables. Goals emerged as a consistent and positive predictor of planning. Gender accounted for health and interpersonal/leisure planning, while work planning behavior was negatively predicted by income. Time perspective also helped to clarify the amount of retirement planning undertaken in the financial and interpersonal/leisure domains. Practical implications for designing retirement interventions are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
58.
基于PBAC模型和IBE的医疗数据访问控制方案   总被引:1,自引:0,他引:1  
张怡婷  傅煜川  杨明  罗军舟 《通信学报》2015,36(12):200-211
医疗卫生领域形成的医疗大数据中包含了大量的个人隐私信息,面临着外部攻击和内部泄密的潜在安全隐患。传统的访问控制模型没有考虑用户访问目的在侧重数据隐私的访问控制中的重要作用,现有的对称、非对称加密技术又都存在密钥管理、证书管理复杂的问题。针对这些问题,提出了综合应用PBAC模型和IBE加密技术的访问控制方案,支持针对医疗数据密文的灵活访问控制。通过加入条件目的概念对PBAC模型进行扩展,实现了对目的树的全覆盖;以病患ID、条件访问位和预期目的作为IBE身份公钥进行病患数据加密,只有通过认证并且访问目的符合预期的用户才能获得相应的私钥和加密数据,从而实现对病患信息的访问。实验结果证明,该方案达到了细粒度访问控制和隐私保护的目的,并具有较好的性能。  相似文献   
59.
从本体论的视角而言,中西方园林是两种性质完全不同的空间.二者服务于不同的目的,乃至于发展出不同的技术方法和表现形式.因此,造园目的是理解园林形式、园林创作的艺术与技术手段以及园林审美的基础,也是通达园林本质的起点.该文基于中国传统园林的发展脉络,辅以适当的文献资料,分析中国传统造园目的的变迁.并以此为线索,揭示中国传统园林的空间本质和园林空间演变的文化逻辑.最后,对中国传统园林的当代价值提出讨论.  相似文献   
60.
简述了基于性能抗震设计思想,判断塔楼超限情况,确定抗震性能目标,并通过对某塔楼进行小 震弹性分析、中震不屈服分析和弹性时程补充分析,对其结构抗震性能进行评估.最后,总结该塔楼基于性能抗震设计的经验,为同类工程设计提供参考.  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