全文获取类型
收费全文 | 7163篇 |
免费 | 946篇 |
国内免费 | 463篇 |
专业分类
电工技术 | 412篇 |
综合类 | 771篇 |
化学工业 | 930篇 |
金属工艺 | 313篇 |
机械仪表 | 363篇 |
建筑科学 | 1174篇 |
矿业工程 | 246篇 |
能源动力 | 119篇 |
轻工业 | 312篇 |
水利工程 | 214篇 |
石油天然气 | 240篇 |
武器工业 | 103篇 |
无线电 | 1120篇 |
一般工业技术 | 533篇 |
冶金工业 | 332篇 |
原子能技术 | 460篇 |
自动化技术 | 930篇 |
出版年
2024年 | 27篇 |
2023年 | 85篇 |
2022年 | 176篇 |
2021年 | 179篇 |
2020年 | 193篇 |
2019年 | 199篇 |
2018年 | 198篇 |
2017年 | 241篇 |
2016年 | 308篇 |
2015年 | 347篇 |
2014年 | 489篇 |
2013年 | 630篇 |
2012年 | 534篇 |
2011年 | 560篇 |
2010年 | 434篇 |
2009年 | 482篇 |
2008年 | 383篇 |
2007年 | 452篇 |
2006年 | 397篇 |
2005年 | 333篇 |
2004年 | 284篇 |
2003年 | 284篇 |
2002年 | 232篇 |
2001年 | 224篇 |
2000年 | 188篇 |
1999年 | 168篇 |
1998年 | 111篇 |
1997年 | 96篇 |
1996年 | 65篇 |
1995年 | 66篇 |
1994年 | 36篇 |
1993年 | 24篇 |
1992年 | 27篇 |
1991年 | 20篇 |
1990年 | 22篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1971年 | 3篇 |
1964年 | 3篇 |
1961年 | 3篇 |
1959年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有8572条查询结果,搜索用时 15 毫秒
11.
Roberson Debi; Davidoff Jules; Davies Ian R. L.; Shapiro Laura R. 《Canadian Metallurgical Quarterly》2004,133(4):554
This study unites investigations into the linguistic relativity of color categories with research on children's category acquisition. Naming, comprehension, and memory for colors were tracked in 2 populations over a 3-year period. Children from a seminomadic equatorial African culture, whose language contains 5 color terms, were compared with a group of English children. Despite differences in visual environment, language, and education, they showed similar patterns of term acquisition. Both groups acquired color vocabulary slowly and with great individual variation. Those knowing no color terms made recognition errors based on perceptual distance, and the influence of naming on memory increased with age. An initial perceptually driven color continuum appears to be progressively organized into sets appropriate to each culture and language. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
12.
Shu‐Li Sun Jing Ma Nan Lv 《International Journal of Adaptive Control and Signal Processing》2008,22(10):932-948
Based on the optimal fusion estimation algorithm weighted by scalars in the linear minimum variance sense, a distributed optimal fusion Kalman filter weighted by scalars is presented for discrete‐time stochastic singular systems with multiple sensors and correlated noises. A cross‐covariance matrix of filtering errors between any two sensors is derived. When the noise statistical information is unknown, a distributed identification approach is presented based on correlation functions and the weighted average method. Further, a distributed self‐tuning fusion filter is given, which includes two stage fusions where the first‐stage fusion is used to identify the noise covariance and the second‐stage fusion is used to obtain the fusion state filter. A simulation verifies the effectiveness of the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
13.
The transit time of the coolant, and thus its velocity, has been measured using the temperature fluctuation at the outlet of a reactor core. An impulse response function estimation is introduced, which substitutes the widely used cross-correlation measurement technique. It is shown in theory and practice that the time delay estimation is improved when using the impulse response function instead of the cross-correlation function in parameter estimation. Extremely low velocities (down to 2 cm/sec) have been measured in a natural circulation regime in a research reactor. 相似文献
14.
噪声测量作为筛选光电耦合器件的一种方法 总被引:2,自引:2,他引:0
本文针对目前用于光电耦合器件筛选方法的不足,提出了用测量耦合器件噪声功率谱的方法来筛选掉噪声值大的器件,给出一批光电耦合器件的测量统计结果及在不同工作点时的噪声功率谱,并给出相应的筛选标准,实验结果表明,这种方法是有效、可行的。 相似文献
15.
复杂目标近场电磁散射的可视化计算方法 总被引:9,自引:1,他引:8
首次介绍了复杂目标近场散射计算的可视化方法。采用非均匀有理B样条曲面(NURBS)精确构造任意形状散射体,结合几何体近场透视变换和Z-Buffer技术实现了基于Windows平台的近场散射计算。提出广义雷达散射截面的概念并给出的若干算例。该方法充分利用了计算机3D图形设备的几何运算能力,运算速度快,严谨高,可扩展性好。 相似文献
16.
本文从梯形水力最优断面的基本思路出发,通过理论分析找到了梯形断面水力计算的一种新方法——即通过特征参数进行梯形断面的水力计算。 相似文献
17.
从微观评价核数据库出发 ,计算给出了快堆谱的伪裂变产物数据 ,包括一群的截面数据和多群的全套中子数据 ,裂变核有2 3 5U和2 3 9Pu。截面数据有全截面、弹性散射、非弹散射、(n ,γ)、(n ,2n)截面 ,多群全套中子数据还包括次级中子角分布和能谱。数据以ENDF B -6格式给出 ,同时还分析讨论了数据误差和可靠性 ,数据可用于实际的快堆计算 相似文献
18.
This study aimed to better understand the impact of business trips on the traveler, the family, and the organization; to learn about maximizing the positive aspects of business travel; and to suggest measures to prevent and manage travel stress. Thirty-five business travelers (American, Israeli, and Swedish) were interviewed about the costs and benefits of their traveling, with a focus on gaining insight into coping strategies. Content analysis of the interviews showed that trips consist of 4 phases--(a) pretrip, (b) journey, (c) stay, and (d) posttrip--and that each phase is characterized by different coping strategies. Business travelers reported using proactive individual and organizational coping strategies in the pretrip phase and a combination of proactive and reactive coping strategies in the other phases. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Sedikides Constantine; Gaertner Lowell; Toguchi Yoshiyasu 《Canadian Metallurgical Quarterly》2003,84(1):60
The culture movement challenged the universality of the self-enhancement motive by proposing that the motive is pervasive in individualistic cultures (the West) but absent in collectivistic cultures (the East). The present research posited that Westerners and Easterners use different tactics to achieve the same goal: positive self-regard. Study 1 tested participants from differing cultural backgrounds (the United States vs. Japan), and Study 2 tested participants of differing self-construals (independent vs. interdependent). Americans and independents self-enhanced on individualistic attributes, whereas Japanese and interdependents self-enhanced on collectivistic attributes. Independents regarded individualistic attributes, whereas interdependents regarded collectivistic attributes, as personally important. Attribute importance mediated self-enhancement. Regardless of cultural background or self-construal, people self-enhance on personally important dimensions. Self-enhancement is a universal human motive. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
吴桂金 《河南机电高等专科学校学报》2004,12(5):64-65
由于过烧石灰的存在和消解不当等原因,造成消石灰安定性不合格,当石灰稳定类路面结构成型或投入使用后,消石灰中的生石灰颗粒开始吸收周围水分,慢慢消解,消解过程中发生体积膨胀,对路面产生破坏。解决石灰安定性问题对防止公路前修后坏,延长路面使用寿命具有积极的现实意义。 相似文献