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   2574篇
  免费   66篇
  国内免费   7篇
电工技术   52篇
综合类   1篇
化学工业   595篇
金属工艺   51篇
机械仪表   56篇
建筑科学   137篇
矿业工程   21篇
能源动力   60篇
轻工业   220篇
水利工程   7篇
石油天然气   7篇
武器工业   1篇
无线电   185篇
一般工业技术   393篇
冶金工业   494篇
原子能技术   28篇
自动化技术   339篇
  2021年   37篇
  2019年   30篇
  2018年   51篇
  2017年   38篇
  2016年   38篇
  2015年   36篇
  2014年   46篇
  2013年   175篇
  2012年   83篇
  2011年   107篇
  2010年   92篇
  2009年   97篇
  2008年   98篇
  2007年   81篇
  2006年   91篇
  2005年   69篇
  2004年   49篇
  2003年   39篇
  2002年   59篇
  2001年   33篇
  2000年   45篇
  1999年   40篇
  1998年   83篇
  1997年   53篇
  1996年   44篇
  1995年   34篇
  1994年   46篇
  1993年   39篇
  1992年   35篇
  1991年   28篇
  1990年   22篇
  1989年   26篇
  1988年   25篇
  1986年   27篇
  1985年   36篇
  1984年   49篇
  1983年   38篇
  1982年   22篇
  1981年   46篇
  1980年   44篇
  1979年   42篇
  1978年   31篇
  1977年   30篇
  1976年   39篇
  1975年   24篇
  1974年   31篇
  1973年   27篇
  1972年   20篇
  1971年   19篇
  1970年   27篇
排序方式: 共有2647条查询结果,搜索用时 15 毫秒
91.
The effects and interactions of heating temperature (60 °C to 73.9 °C), salt (0.0 % to 4.5 %?w/v), sodium pyrophosphate (0.0 % to 0.5 %?w/v), and sodium lactate (0.0 % to 4.5 %?w/v) on the heat resistance of a five-strain mixture of Listeria monocytogenes in 75 % lean ground beef were examined. Meat samples in sterile filtered stomacher bags were heated in a temperature controlled waterbath to determine thermal death times. The recovery medium was tryptic soy agar supplemented with 0.6 % yeast extract and 1 % sodium pyruvate. Weibull survival functions were employed to model the primary survival curves. Then, survival curve-specific estimated parameter values obtained from the Weibull model were used for determining a secondary model. The results indicate that temperature and salt have a large impact on the inactivation kinetics of L. monocytogenes, while sodium lactate (NaL) has an impact in the presence of salt. The model presented in this paper for predicting inactivation of L. monocytogenes can be used as an aid in designing lethality treatments meant to control the presence of this pathogen in ready-to-eat products.  相似文献   
92.
93.
Battery cells being electrically disconnected resulting from degradation, mechanical stress, or corrosion can lead to hazardous situations during operation of electric vehicles or storage systems in stationary applications. The mentioned errors can be acceptable in some cases when cells or cell strings are connected in parallel, but the failure is to be detected in order to guarantee the reliable and safe operation of the battery system. A method enabling the estimation whether individual battery cells are faulty (cell error or electrically disconnected) by evaluating the mean impedance and capacity information of cell groups is introduced and validated.  相似文献   
94.
95.
96.
A number of polyphosphazenes with negatively charged β‐alanine (β‐Ala) and γ‐amino butyric acid (GABA) side groups were synthesized and studied for their ability to initiate the growth of hydroxyapatite (HAp) during exposure to simulated body fluid (SBF). All the polymers were hydrolytically sensitive, with the final hydrolysis rate dependent on the specific active side groups (GABA > β‐Ala). These systems also underwent extensive mineralization, with calcium phosphate deposited across their entire surface during exposure to SBF (up to 115 wt % gain after 4 weeks). This degree of deposition is a major advance over previously reported polyphosphazene systems, which underwent a maximum of 27 wt % gain after immersion in SBF for 4 weeks. The extent of mineralization over the surface was monitored using environmental scanning electron microscopy (ESEM) coupled with energy dispersive X‐ray spectroscopy (EDS). In addition, X‐ray diffraction (XRD) was used to determine the identity of the mineralized material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41741.  相似文献   
97.
98.
99.
Conference news     
RESOURCES: ENVIRONMENT AND POLICY, by John Fernie and Alan Pitkethly, Harper and Row, London, 1985, 338 pp. (#bp12.95, paperback)

THE ECONOMICS OF FORESTRY AND NATURAL RESOURCES, by Per‐Olov Johansson and Karl‐Gustaf Lofgren, Basil Blackwell, Oxford, 1985, 292 pp. (#bp29.50, hardback only)

ENVIRONMENTAL PROTECTION: STANDARDS, COMPLIANCE AND COSTS, edited by T. J. Lack, J. Wiley &; Son, Chichester, 1984, 329 pp. (#bp30, hardback)

ENVIRONMENT AND ENFORCEMENT: REGULATION AND THE SOCIAL DEFINITION OF POLLUTION, by K. Hawkins, Clarendon Press, Oxford, 1984, 253 pp. (#bp15 hardback; #bp6.95, paperback)

ENVIRONMENTAL POLICY, VOLUME 1: ELEMENTS OF ENVIRONMENTAL ANALYSIS, by George Tolley, Philip Graves and Glenn Blomquist, Ballinger, Cambridge, Mass, and Harper and Row, London, 1981. (#bp27.50, hardback)

ENVIRONMENTAL POLICY, VOLUME 4: SOLID WASTES, by George Tolley, Jospeh Havlicek and Robert Fabian, Ballinger, Cambridge, Mass. and Harper and Row, London, 1985. (#bp44.00, hardback)

World Health Organisation, ENVIRONMENTAL POLLUTION CONTROL IN RELATION TO DEVELOPMENT, World Health Organisation, Geneva, Technical Report Series, 718, 1985, 63 pp.

TRANSPORT IS FOR PEOPLE: NINTH INTERNATIONAL SYMPOSIUM ON THEORY AND PRACTICE IN TRANSPORT ECONOMICS, European Conference of Ministers of Transport, 1983, Paris (#bp15.00)

RECREATION MANAGEMENT AND PRICING, by A. G. Bovaird, M. J. Tricker and R. Stoakes, Gower Press, Aldershot, 1984, 182 pp. (#bp15, hardback)

URBAN LAND AND SHELTER FOR THE POOR, by Patrick McAuslan, Earthscan#shInternational Institute for Environment and Development, London, 1985, 145 pp.

CARING FOR THE UNEMPLOYED. Prepared for the Association of Metro‐polital Authorities by Susan Balloch, Chris Hume, Brian Jones and Peter Westland. Publishers: Bedford Square Press, London, 1985, for the National Council for Voluntary Organisations.

THE LONG‐TERM UNEMPLOYED. ACTION FOR A FORGOTTEN MILLION, by Peter Ashby (Head, NVCO Policy Analysis Unit). An NCVO Policy Discussion document, Bedford Square Press, London (1985).

ANTHROPOGENIC COMPOUNDS: Volume 3 Part C of The Handbook of Environmental Chemistry, edited by O. Hutzinger, Springer‐Verlag, Germany, 248 pp. 1986. (DM 188.00)

HEAVY METALS IN NATURAL WATERS: APPLIED MONITORING AND IMPACT ASSESSMENT, by James W. Moore and S. Ramamoorthy, Springer‐Verlag, U.S.A. and Germany, viii #pl 268 pages, index, 1984. (DM 108.00)

DESTRUCTION AND DISPOSAL OF PCBs BY THERMAL AND NON‐THERMAL METHODS, by D. G. Ackerman, L. L. Scinto, P. S. Bakshi, R. G. Delumyea, R. J. Johnson, G. Richard, A. M. Takata and E. M. Sworzyn. Noyes Data Corporation, Park Ridge, New Jersey, 1983, xiv #pl 417 pages (no index). (#dl48.00)

ELECTROSTATIC PRECIPITATOR MANUAL (Pollution Technology Review No. 91), by Jack R. McDonald and Alan H. Dean, Noyes Data Corporation, U.S.A., 1982. (#dl48.00)

PATTY'S INDUSTRIAL HYGIENE AND TOXICOLOGY, edited by Lewis J. Cralley and Lester V. Cralley, Volume 3 (2nd Edition)—Theory and Rationale of Industrial Hygiene Practice: (i) Volume 3A—The Work Environment (#bp97.20); (ii) Volume 3B—Biological Responses (#bp92.00) J. Wiley and Sons Ltd., Chichester U.K. 1985.

SAFE DRINKING WATER. THE IMPACT OF CHEMICALS ON A LIMITED RESOURCE, edited by R. G. Rice, J. Wiley and Sons, Chichester, U.K., Lewis Publishers Inc. Chelsea MI, 1985. (#bp36.00)

PLANTS FOR ARID LANDS. (Proceedings of the Kew International Conference on Economic Plants for Arid Lands held in the Jodrell Laboratory, Royal Botanic Gardens, Kew, England, 23‐27 July 1984), edited by G. E. Wickens, J. R. Goodwin and D. V. Field. George Allen and Unwin, London, 1985. (#bp30.00)

REGULATED RIVERS, edited by A. Lillehammer and S. J. Saltveit, Univer‐sitetsforlaget AS, Oslo, 1984. (#bp47.50)

NUTRIENT CYCLING IN TROPICAL FOREST ECOSYSTEMS, by C. F. Jordan, Wiley, Chichester, 1985. (#bp13.45)  相似文献   
100.
County manufacturing employment can be projected for the purpose of verifying a population projection. First, future county manufacturing employment is derived from a population projection by using assumed ratios of labor force participation, unemployment, and manufacturing employment. Second, independent projections of manufacturing employment are made, based upon statistical projections of county and national manufacturing employment trends. Third, both these quantitative projections are checked against the knowledge and judgments of leading businessmen and industrialists in the community, and adjustments are made in the quantities.  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