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   57292篇
  免费   5453篇
  国内免费   2589篇
电工技术   3474篇
技术理论   7篇
综合类   3697篇
化学工业   9511篇
金属工艺   3531篇
机械仪表   3705篇
建筑科学   4264篇
矿业工程   2041篇
能源动力   1739篇
轻工业   3585篇
水利工程   972篇
石油天然气   3677篇
武器工业   532篇
无线电   6553篇
一般工业技术   7202篇
冶金工业   2817篇
原子能技术   783篇
自动化技术   7244篇
  2024年   342篇
  2023年   1150篇
  2022年   1942篇
  2021年   2718篇
  2020年   2010篇
  2019年   1613篇
  2018年   1856篇
  2017年   2071篇
  2016年   1886篇
  2015年   2432篇
  2014年   3058篇
  2013年   3607篇
  2012年   3810篇
  2011年   4102篇
  2010年   3464篇
  2009年   3257篇
  2008年   3244篇
  2007年   3044篇
  2006年   2959篇
  2005年   2484篇
  2004年   1739篇
  2003年   1509篇
  2002年   1484篇
  2001年   1277篇
  2000年   1294篇
  1999年   1355篇
  1998年   1056篇
  1997年   920篇
  1996年   835篇
  1995年   651篇
  1994年   541篇
  1993年   354篇
  1992年   290篇
  1991年   219篇
  1990年   185篇
  1989年   148篇
  1988年   121篇
  1987年   65篇
  1986年   62篇
  1985年   39篇
  1984年   31篇
  1983年   27篇
  1982年   28篇
  1981年   14篇
  1980年   11篇
  1979年   9篇
  1976年   6篇
  1970年   2篇
  1959年   5篇
  1951年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Liu  Song  Cui  Yuan-Zhen  Zou  Nian-Jun  Zhu  Wen-Hao  Zhang  Dong  Wu  Wei-Guo 《计算机科学技术学报》2019,34(2):456-475
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...  相似文献   
24.
Photothermal therapy (PTT) has attracted great attention due to its noninvasive and effective use against cancer. Various photothermal agents (PTAs) including organic and inorganic PTAs have been developed in the last decades. Organic PTAs based on small-molecule dyes exhibit great potential for future clinical applications considering their good biocompatibility and easy chemical modification or functionalization. In this review, we discuss the recent progress of organic PTAs based on small-molecule dyes for enhanced PTT. We summarize the strategies to improve the light penetration of PTAs, methods to enhance their photothermal conversion efficiency, how to optimize PTAs’ delivery into deep tumors, and how to resist photobleaching under repeated laser irradiation. We hope that this review can rouse the interest of researchers in the field of PTAs based on small-molecule dyes and help them to fabricate next-generation PTAs for noninvasive cancer therapy.  相似文献   
25.
26.
煤电平均供电煤耗作为评价能源系统效率的指标已在行业内广泛应用。但该项指标无法很好地反映一个国家、地区的用电结构与用电能耗水平。为此,参照行业内普遍采用的火电厂发电煤耗和供电煤耗指标,定义“综合用电煤耗”,即用户每用1 kW?h电“消耗”的标准煤量(单位:g/(kW?h))。在此基础上,提出“综合发电煤耗”与“综合供电煤耗”的概念,形成完整的指标评价体系。对近年典型省份指标值的研究表明,该指标体系能够很好地反映供给侧国家、省区或企业的发电结构与电能生产能耗水平。这一指标体系能够为正确理解和计算用电、输电与电能替代项目的化石能源消耗量及其排放量提供依据。  相似文献   
27.
Thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition (EB-PVD) or plasma spray (PS) usually suffer from molten calcium-magnesium-alumino-silicate (CMAS) attack. In this study, columnar structured YSZ coatings were fabricated by plasma spray physical vapor deposition (PS-PVD). The coatings were CMAS-infiltrated at 1250?°C for short terms (1, 5, 30?min). The wetting and spreading dynamics of CMAS melt on the coating surface was in-situ investigated using a heating microscope. The results indicate that the spreading evolution of CMAS melt can be described in terms of two stages with varied time intervals and spreading velocities. Besides, the PS-PVD columnar coating (~100?μm thick) was fully penetrated by CMAS melt within 1?min. After the CMAS attack for 30?min, the original feathered-YSZ grains (tetragonal phase) in both PS-PVD and EB-PVD coatings were replaced by globular shaped monoclinic ZrO2 grains in the interaction regions.  相似文献   
28.
29.
Jia  Yuan  Wang  Yangli  Song  Rui  Li  Jiandong 《Multimedia Tools and Applications》2015,74(6):1777-1803
Multimedia Tools and Applications - In Wyner-Ziv (WZ) video coding, decoder side information (SI) takes a key role in a WZ video codec among other building blocks. In this paper, we review the...  相似文献   
30.
Microwave lignite drying with assistance of biomass-derived char was addressed and effect of bio-char on drying rate and energy consumption was investigated in this work. Effective diffusion coefficient and activation energy for the drying process were also analyzed. The results indicated the drying process was largely dependent on the variation of sample temperature. Bio-char originated from pine wood was most favorable for lignite drying, considering its better promoting effect and advanced security. There existed an optimal bio-char addition ratio for drying process at different power. The corresponding optimal ratio was 10% at 231?W and 15% at 385?W, at which the biggest drying rate and the least energy consumption were reached. It was compared lignite drying initiated at 385?W was better for energy conservation. Effective diffusivity was improved and activation energy was simultaneously reduced, with the addition of bio-char. The minimum activation energy was 15.54?W?·?g?1, which was gained at bio-char addition ratio of 10%. The results revealed the effect of bio-char on depressing activation energy could rival that of metal-based additives. The drying process with assistance of microwave and bio-char could present technical and economical benefits on lignite upgrading.  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