全文获取类型
收费全文 | 14209篇 |
免费 | 990篇 |
国内免费 | 682篇 |
专业分类
电工技术 | 955篇 |
技术理论 | 8篇 |
综合类 | 1221篇 |
化学工业 | 591篇 |
金属工艺 | 741篇 |
机械仪表 | 1023篇 |
建筑科学 | 2509篇 |
矿业工程 | 433篇 |
能源动力 | 1045篇 |
轻工业 | 664篇 |
水利工程 | 534篇 |
石油天然气 | 643篇 |
武器工业 | 98篇 |
无线电 | 947篇 |
一般工业技术 | 910篇 |
冶金工业 | 686篇 |
原子能技术 | 174篇 |
自动化技术 | 2699篇 |
出版年
2024年 | 58篇 |
2023年 | 145篇 |
2022年 | 319篇 |
2021年 | 386篇 |
2020年 | 438篇 |
2019年 | 271篇 |
2018年 | 296篇 |
2017年 | 364篇 |
2016年 | 424篇 |
2015年 | 471篇 |
2014年 | 915篇 |
2013年 | 1005篇 |
2012年 | 996篇 |
2011年 | 1103篇 |
2010年 | 882篇 |
2009年 | 904篇 |
2008年 | 811篇 |
2007年 | 987篇 |
2006年 | 891篇 |
2005年 | 742篇 |
2004年 | 627篇 |
2003年 | 586篇 |
2002年 | 438篇 |
2001年 | 339篇 |
2000年 | 289篇 |
1999年 | 267篇 |
1998年 | 145篇 |
1997年 | 115篇 |
1996年 | 128篇 |
1995年 | 82篇 |
1994年 | 74篇 |
1993年 | 41篇 |
1992年 | 43篇 |
1991年 | 34篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 28篇 |
1984年 | 25篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1975年 | 6篇 |
1972年 | 4篇 |
1966年 | 8篇 |
1956年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
风险评估在加氢装置的应用 总被引:1,自引:0,他引:1
广州石化加氢(二)B装置采用基于风险的检测(RBI)技术,对装置的静设备与管道使用RBI软件RB—eye进行定量、定性分析以及失效概率、失效后果的评价,评估了装置的风险情况,制定了装景基于风险分析的检验策略。 相似文献
72.
任兴洲 《重庆理工大学学报(自然科学版)》2006,20(3):1-5
2005年,我国经济呈现高位平稳增长的特征,各项经济指标总体上继续向好.与此同时,经济运行中也出现了一些新情况、新问题,需要引起足够的重视.2006年,针对部分生产资料行业产能过剩等突出问题,应积极推进产业结构调整,促进经济增长方式转变.同时,应将扩大消费需求作为宏观政策的主要着力点. 相似文献
73.
孟政军 《石油化工安全环保技术》2006,22(2):3-7
运用危险性分析和工作危害分析法,对一套常减压装置适应性改造的危险性进行分析, 找出主要影响因素,制订对策,确保装置改造和生产安全。 相似文献
74.
Brent M. Phares Glenn A. Washer Dennis D. Rolander Benjamin A. Graybeal Mark Moore 《Canadian Metallurgical Quarterly》2004,9(4):403-413
Routine inspection is the most common form of highway bridge inspection to satisfy the requirements of the National Bridge Inspection Standards. The accuracy and reliability of documentation generated during these inspections are critical to the allocation of Department of Transportation construction, maintenance, and rehabilitation resources. Routine inspections are typically completed using only the visual inspection technique and rely heavily on subjective assessments made by bridge inspectors. In light of this, and given the fact that visual inspection may have other limitations that influence its reliability, the Federal Highway Administration initiated an investigation to examine the reliability of visual inspection as it is currently applied to bridges in the United States. This paper will summarize results from this study related to the accuracy and reliability of routine inspection documentation. A number of important conclusions were developed from the experimental study. Generally, it was found that all structural condition documentation is collected with significant variability. Specifically, 95% of primary element condition ratings for individual bridge components will vary within two rating points of the average and only 68% will vary within one point. Documentation generally collected to support condition ratings also has significant variability as exemplified by the number and types of field notes and photographs taken by inspectors. With respect to the use of element-level inspections, it was found that element usage was generally consistent with the Commonly Recognized Element Guide. However, there is significant variability in the condition state assignments of those elements and in some cases the condition states are not applied correctly to particular elements. 相似文献
75.
Greater use of psychological research and practice knowledge in the formulation of social policy is necessary to enhance the well-being of U.S. citizens and communities. Although historically there are instances in which psychological and social science research and practice have had a substantial influence on federal policy, for the most part the relationships among research, practice, and policy have been tenuous. Three cases in which research has substantively influenced policy over the past 80 years are reviewed: Keynesian economics, Head Start legislation, and the activities of conservative think tanks. Several recommendations are made for ways in which psychologists can enhance their influence in the policy arena, including communicating directly with policymakers regarding relevant policy findings and knowledge gleaned from practice; conducting interdisciplinary, multilevel research as well as evaluation research (including qualitative data drawn from practice settings); and networking among researchers, practitioners, policy advocates, and social action groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Reliability evaluation and optimisation of imperfect inspections for a component with multi-defects 总被引:1,自引:1,他引:0
Jianmin Zhao A.H.C. Chan C. Roberts K.B. Madelin 《Reliability Engineering & System Safety》2007,92(1):65-73
In this paper, a model is developed to evaluate the reliability and optimise the inspection schedule for a multi-defect component. The model uses a non-homogeneous Poisson process (NHPP) method in conjunction with a delay time approach. The inspections are designed to detect any defects in the component, however it can be imperfect. The defect is a definable state before a functional failure happens to the component. Occurrences of defects are assumed to follow an NHPP and a defect will be minimally repaired if it is identified during an inspection. It is shown that the failures occurring in an interval of inspection will also follow an NHPP. The situation of imperfect inspections and non-constant inspection intervals are considered. An algorithm is presented to optimise the intervals of inspections in order to maximise the reliability of the component, and the properties of the algorithm are shown. A numerical example with parametric study is given to show the performance of the model and the algorithm. 相似文献
77.
分析了造价监理工程师如何在在施工前期的招投标、施工组织方案技术经济评价和工程施工阶段的签证、索赔、进度款控制等方面对造价进行合理确定和有效控制。 相似文献
78.
徐凤平 《稀有金属与硬质合金》2003,31(2):55-57
剖析了企业供应工作中存在的物资入库质量验收问题及存在的原因,提出了搞好企业物资供应管理,加强物资质量验收的对策。 相似文献
79.
D. F. CANNON K.-O. EDEL S. L. GRASSIE K. SAWLEY 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(10):865-886
For about 150 years, the steel rail has been at the very heart of the world's railway systems. The rail works in a harsh environment and, as part of the track structure, it has little redundancy; thus, its failure may lead to catastrophic derailment of vehicles, the consequences of which can include death, injury, costs and loss of public confidence. These can have devastating and long‐lasting effects on the industry. Despite the advances being made in railway permanent way engineering, inspection and rail‐making technology, continually increasing service demands have resulted in rail failure continuing to be a substantial economic burden and a threat to the safe operation of virtually every railway in the world. This paper presents an overview of rail defects and their consequences from the earliest days of railways to the present day. 相似文献
80.
结合青藏铁路建设物资储备基地的实际情况,探讨了铁路线统购统发材料的管理模式及业务流程,总结出在实际工作中应借鉴的经验和注意的问题。 相似文献