全文获取类型
收费全文 | 26713篇 |
免费 | 775篇 |
国内免费 | 32篇 |
专业分类
电工技术 | 330篇 |
综合类 | 13篇 |
化学工业 | 5893篇 |
金属工艺 | 520篇 |
机械仪表 | 482篇 |
建筑科学 | 1159篇 |
矿业工程 | 332篇 |
能源动力 | 653篇 |
轻工业 | 1726篇 |
水利工程 | 226篇 |
石油天然气 | 245篇 |
无线电 | 1708篇 |
一般工业技术 | 4093篇 |
冶金工业 | 6155篇 |
原子能技术 | 265篇 |
自动化技术 | 3720篇 |
出版年
2022年 | 201篇 |
2021年 | 413篇 |
2020年 | 266篇 |
2019年 | 346篇 |
2018年 | 425篇 |
2017年 | 368篇 |
2016年 | 486篇 |
2015年 | 395篇 |
2014年 | 615篇 |
2013年 | 1657篇 |
2012年 | 941篇 |
2011年 | 1208篇 |
2010年 | 925篇 |
2009年 | 979篇 |
2008年 | 1152篇 |
2007年 | 1068篇 |
2006年 | 974篇 |
2005年 | 884篇 |
2004年 | 744篇 |
2003年 | 712篇 |
2002年 | 707篇 |
2001年 | 485篇 |
2000年 | 391篇 |
1999年 | 446篇 |
1998年 | 440篇 |
1997年 | 430篇 |
1996年 | 474篇 |
1995年 | 443篇 |
1994年 | 452篇 |
1993年 | 437篇 |
1992年 | 432篇 |
1991年 | 272篇 |
1990年 | 410篇 |
1989年 | 388篇 |
1988年 | 336篇 |
1987年 | 404篇 |
1986年 | 348篇 |
1985年 | 441篇 |
1984年 | 463篇 |
1983年 | 399篇 |
1982年 | 376篇 |
1981年 | 301篇 |
1980年 | 298篇 |
1979年 | 357篇 |
1978年 | 299篇 |
1977年 | 238篇 |
1976年 | 220篇 |
1975年 | 245篇 |
1974年 | 222篇 |
1973年 | 224篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
981.
982.
Robert A. Creo 《Alternatives to the High Cost of Litigation》2015,33(10):147-148
Editor's note: Longtime Alternatives columnist Bob Creo, a veteran Pittsburgh neutral, is revisiting his classic CPR Institute website columns of a decade ago in a Back to Basics Series that he has subtitled “Human Problems, Human Solutions.” These updated and expanded columns, in print for the first time, began late last year. He has revisited and re‐examined mediation‐room techniques and practice issues. This month, he returns to the second column he wrote at www.cpradr.org a decade ago, and brings it forward. 相似文献
983.
In June 2010, the US Environmental Protection Agency (EPA) finalized a new, very stringent National Ambient Air Quality Standard (NAAQS) for sulfur dioxide1 (SO2). 相似文献
984.
985.
Kenneth J. Kokjer Katrina A. Ray‐Landis Robert A. Dieterich 《The International journal of environmental studies》2013,70(2-3):103-113
A portable computer system is described which supports timely data management for reindeer herding. An initial version has been in use for two years, supporting research on reindeer diseases. Versions are being developed which will expand the system to support commercial herd management. The hardware system is integrated from commercially available equipment. The software is currently composed of a set of ten programs, with others under development for enhancements and modifications. At field roundups, the computer allows new animals to be added to the data base plus rapid access to information on existing individual animals. Historical information can be displayed, including detailed historical records of reproductive activity, medical treatments, serological exam results, and observations of anomalies (e.g. infections, injuries, etc.). In the field, or in the lab, the data base may be accessed for information on specific animals and for summaries of herd data. 相似文献
986.
Therese P. McAllister John L. Gross Fahim Sadek Steven Kirkpatrick Robert A. MacNeill Mehdi Zarghamee Omer O. Erbay Andrew T. Sarawit 《Fire Technology》2013,49(3):709-739
The National Institute of Standards and Technology (NIST) conducted an extensive investigation of the collapse of World Trade Center towers (WTC 1 and WTC 2) and the WTC 7 building. This paper describes the component, subsystem, and global analyses performed for the reconstruction of the structural response of WTC buildings 1, 2, and 7 to impact and fire damage. To illustrate the component and subsystem analyses, the approach taken for simulating the performance of concrete slabs and shear stud connectors in composite floors subject to fire conditions are presented, as well as steel floor framing connections for beams and girders. The development of the global models from the component and subsystem analyses is briefly described, including the sets of input data used to bound the probable conditions of impact and fire damage. The final analysis results that were used to develop the probable collapse hypotheses, and a comparison of the results against observed events, are presented for each building. A review of research activities focused on improving understanding of structural system response to multi-floor fires following the WTC disaster is also provided. 相似文献
987.
988.
Iain MacGill Robert Passey Terry Daly 《The International journal of environmental studies》2013,70(6):751-763
There is considerable debate regarding the potential role of Carbon Capture and Storage (CCS) technologies in reducing Australia's greenhouse emissions. The latest climate change science suggests that major (60% or more by 2050), rapid (peaking within 20 years) cuts in global emissions may be required to avoid dangerous climate change. There are a number of existing abatement options including energy efficiency, various renewable energy technologies, nuclear power and fuel switching to natural gas; as well as emerging options including CCS. We outline a simple technology assessment framework for policymakers to evaluate these different options given the climate change imperative. This framework includes technology status, delivered energy services, present and possible future costs, potential scale of abatement, potential speed of deployment and other possible social outcomes. Application of this framework to CCS suggests that it should be considered as a promising, but still somewhat unproven, option that potentially offers very significant abatement potential and good integration into the existing energy industry. There are, however, some outstanding questions regarding its effectiveness and safety, its abatement is likely to come at significant cost, and it is unlikely to be able to make a significant contribution for well over a decade. The Australian policy implications are that while government support for R&D and Demonstration of CCS is appropriate and should in our view be expanded, the major priority should be to support greater deployment of existing abatement options including energy efficiency, efficient gas-fired generation and cogeneration and renewable energy. Such policy support is noticeably lacking at present. 相似文献
989.
A two-dimensional, particle-based biofilm model coupled with mass transport and computational fluid dynamics was developed to simulate autotrophic denitrification in a spiral-wound membrane biofilm reactor (MBfR), where hydrogen is supplied via hollow-fiber membrane fabric. The spiral-wound configuration consists of alternating layers of plastic spacer net and membrane fabric that create rows of flow channels, with the top and bottom walls comprised of membranes. The transversal filaments of the spacer partially obstruct the channel flow, producing complex mixing and shear patterns that require multidimensional representation. This study investigated the effect of hydrogen and nitrate concentrations, as well as spacer configuration, on biofilm development and denitrification fluxes. The model results indicate that the cavity spacer filaments, which rest on the bottom membranes, cause uneven biofilm growth. Most biofilm resided on the bottom membranes, only in the wake of the filaments where low shear zones formed. In this way, filament configuration may help achieve a desired biofilm thickness. For the conditions tested in this study, the highest nitrate fluxes were attained by minimizing the filament diameter and maximizing the filament spacing. This lowered the shear stress at the top membranes, allowing for more biofilm growth. For the scenarios studied, biomass limitation at the top membranes hindered performance more significantly than diffusion limitation in the thick biofilms at the bottom membranes. The results also highlighted the importance of two-dimensional modeling to capture uneven biofilm growth on a substratum with geometrical complexity. 相似文献
990.
Carl T. Haas Ana Maria Rodriguez Robert Glover Paul M. Goodrum 《Construction Management & Economics》2013,31(6):633-641
Recent studies show the construction industry in the USA is facing a long term labour shortage. Multiskilling has been suggested as a strategy to address this issue by utilizing existing workers more efficiently. Multiskilling decreases the number of workers hired for a project and can improve productivity. Additional benefits include higher income and increased employability of the workforce. To take full advantage of these benefits, the workforce strategy and the planning and scheduling processes of a construction project must be adapted to use multiskilling effectively and efficiently. The multiskilled workforce should be scheduled and organized to maximize the duration of employment for workers, reduce the overall labour requirements and cover the skills combinations required by the project. This research synthesizes and formalizes the methods that successful construction companies are currently applying to implement a multiskilled workforce. A methodology for implementing multiskilling is outlined as well. 相似文献