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   48699篇
  免费   4980篇
  国内免费   3353篇
电工技术   2782篇
技术理论   4篇
综合类   5370篇
化学工业   6738篇
金属工艺   3334篇
机械仪表   2088篇
建筑科学   3673篇
矿业工程   2699篇
能源动力   2257篇
轻工业   3536篇
水利工程   1645篇
石油天然气   2955篇
武器工业   853篇
无线电   4648篇
一般工业技术   5211篇
冶金工业   3262篇
原子能技术   1084篇
自动化技术   4893篇
  2024年   192篇
  2023年   638篇
  2022年   1313篇
  2021年   1572篇
  2020年   1795篇
  2019年   1507篇
  2018年   1453篇
  2017年   1873篇
  2016年   2049篇
  2015年   2033篇
  2014年   3071篇
  2013年   3354篇
  2012年   3759篇
  2011年   3797篇
  2010年   2833篇
  2009年   2836篇
  2008年   2561篇
  2007年   3089篇
  2006年   2643篇
  2005年   2275篇
  2004年   1955篇
  2003年   1660篇
  2002年   1422篇
  2001年   1211篇
  2000年   1055篇
  1999年   860篇
  1998年   707篇
  1997年   615篇
  1996年   567篇
  1995年   484篇
  1994年   373篇
  1993年   274篇
  1992年   263篇
  1991年   202篇
  1990年   180篇
  1989年   126篇
  1988年   91篇
  1987年   58篇
  1986年   54篇
  1985年   39篇
  1984年   37篇
  1983年   22篇
  1982年   22篇
  1981年   18篇
  1980年   17篇
  1979年   6篇
  1978年   8篇
  1977年   7篇
  1975年   9篇
  1959年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
《Ergonomics》2012,55(10):1503-1514
The primary objective of this paper was to compare in-shoe loading for different models of running shoe using measurements of force distribution. It was hypothesised that a shoe designed with minimal focus on cushioning would demonstrate significantly higher peak forces and rates of loading than running shoes designed with cushioning midsoles. Loading was compared using in-shoe peak forces for six footwear conditions. It was found that peak rate of loading at the heel provided clear distinctions between shoes. In support of the study hypothesis, the shoe with minimal focus on cushioning had a significantly higher rate of loading than all but one of the other test shoes. Data collected for midfoot and forefoot areas of the foot highlighted the importance of considering loading across the foot surface. The results of the present study demonstrate that pressure insoles provide a useful tool for the assessment of loading across the foot plantar surface for different footwear conditions. There are numerous models of running shoe for individuals to select from, with limited information available regarding the performance of the shoes during running. The current study demonstrates differences in loads across the foot plantar surface during running, indicating differences in performance for different footwear models.  相似文献   
82.
《Ergonomics》2012,55(12):1339-1349
This study presents the biological responses to shiftwork in two groups of workers with different shiftwork rotas. Biological responses were studied by recording the heart rate and the changes in the circadian profile of salivary cortisol over 24?h (RIA assays). Various items were recorded through questionnaires aimed at determining self appreciation of sleep quantity, stress, health, satisfaction at work and in private lives. Thirty two male subjects aged from 23 to 56, working for the same company, having given their informed consent, took part in the study. The study was carried out under realistic conditions (at the work place) under the control of an occupational physician. Sixteen day-workers (8 am?–?6?pm) served as a reference group. Eight shiftworkers included in alternate schedules (morning M 4 am?–?12 am, evening E 12 am?–?8?pm, night N 8?pm?–?4 am) according to a system M, S, N 3/2, (3 work, 2 rest) and eight according to a system 7/5 (3M/2S/2N/5R, 2/3/2/5, 2/2/3/5) constituted the groups of shiftworkers respectively named 3/2 and 7/5. All subjects had comparable ages and BMIs. Shiftworkers expressed a higher stress level and frequency of health problems and a lower satisfaction at work than the control. Among the three groups, the 7/5 group had the best health and fitness score and was in need of less sleep. Heart rate was not affected by shift work. Conversely, consistent changes appeared in cortisol circadian profiles, the greatest changes appearing for the night shift and among the two groups of shiftworkers, more particularly for the 7/5 group. These changes correlated with self-perceived constraints of work and showed the difficulties of adaptation to shiftwork.  相似文献   
83.
84.
In this paper, field experimental comparison is made between a small track-type experimental prototype skidder and a J-50 skidding tractor. Experimental data, including skidding productivity, soil compaction on skidding trails, and damage rate of the residual trees, are analyzed. The results indicate that with the condition of scattered skidding area and low skidding volume per cycle, small track-type experimental prototype skidder has advantage on working and a higher skidding productivity. It makes lower soil compaction to the skidding trails in the depth of 0-5 cm, 5-10 cm, and 10-15 cm. Under the same work conditions, the damage rate of the residual trees made by small track-type experimental prototype skidder is only 1/5 of those made by J-50 type skidding tractor. The damage rate is reduced by 80%.  相似文献   
85.
分析了影响对外汉语专业毕业生就业的各种因素,主张以积极的心态看待就业形势,正视存在的问题,加强专业建设,优化课程设置,落实实践环节,提升专业素质和求职技能,以提高对外汉语专业学生就业率和就业质量。  相似文献   
86.
在《关于正确处理人民内部矛盾的问题》一文中,毛泽东从哲学高度指出了社会主义社会存在两类性质不同的矛盾,首次创立了关于社会主义社会矛盾的学说,本文将以全新的视角,解读其重大理论意义和实践意义,深入研究其理论价值,从而为当代中国构建社会主义和谐社会和全面建设小康社会提供理论支撑.  相似文献   
87.
Microwave permeability spectra of single Co nanotube under equilibrium state have been studied by micromagnetics simulation.More than four obvious resonance peaks have been found(11.72,24.20,33.18 and 39.55 GHz).Such large resonance frequency cannot be found in other traditional magnetic materials.The configurations of magnetic moments along the nanotube have been simulated.The results show that the top end of nanotube has a"flow-out"pattern of magnetic moments configuration.The bottom end has a"flow-in"pattern of magnetic moments configuration.The magnetic moments within the main body of nanotube are aligned perfectly along the length of nanotube.The magnitude of natural resonance peak is strongly related to the volume fraction of a zone,which has the same orientation of magnetic moments.Large microwave permeability values have been found for single nanotube.The generalized Snoek’s law has been used to validate the micromagnetics simulations in this paper.  相似文献   
88.
文中针对原水水质特点,利用常规+活性炭吸附工艺对原水进行处理,着重分析了活性炭对有机物的去除效果。  相似文献   
89.
一种新型ICA算法在RFID系统中的应用   总被引:1,自引:0,他引:1  
针对无线射频识别系统在通信过程中的防碰撞问题,从信号处理的角度,提出一种基于盲源信号并行分离技术的防碰撞处理算法,其中包括信号白化技术,以及一种改进的独立元分析(ICA)信号并行分离方法.功能仿真结果证明,该算法的吞吐率最高达到69%,与吞吐率只有18%的传统Aloha算法相比,该算法能提高防碰撞能力.  相似文献   
90.
论述了声纹识别的相关概念、应用领域及其区别于其他身份认证的优势,从软件方面构建了一个基于Matlab的声纹识别系统,并对整个系统进行了仿真实验,实验结果表明该系统具有较高的识别率,可应用于有限人群的身份认证。  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