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   205851篇
  免费   15789篇
  国内免费   7788篇
电工技术   11228篇
技术理论   14篇
综合类   11213篇
化学工业   35699篇
金属工艺   10525篇
机械仪表   11997篇
建筑科学   16407篇
矿业工程   4943篇
能源动力   5849篇
轻工业   12682篇
水利工程   3211篇
石油天然气   11075篇
武器工业   1345篇
无线电   25480篇
一般工业技术   26698篇
冶金工业   11498篇
原子能技术   2114篇
自动化技术   27450篇
  2024年   881篇
  2023年   3262篇
  2022年   5827篇
  2021年   7877篇
  2020年   5795篇
  2019年   5007篇
  2018年   5414篇
  2017年   6199篇
  2016年   5693篇
  2015年   7290篇
  2014年   9519篇
  2013年   12270篇
  2012年   12224篇
  2011年   13871篇
  2010年   11610篇
  2009年   11460篇
  2008年   10872篇
  2007年   10467篇
  2006年   10857篇
  2005年   9629篇
  2004年   6563篇
  2003年   5780篇
  2002年   5251篇
  2001年   4723篇
  2000年   4869篇
  1999年   5654篇
  1998年   5448篇
  1997年   4458篇
  1996年   4027篇
  1995年   3352篇
  1994年   2794篇
  1993年   2215篇
  1992年   1710篇
  1991年   1296篇
  1990年   1031篇
  1989年   889篇
  1988年   695篇
  1987年   505篇
  1986年   403篇
  1985年   341篇
  1984年   212篇
  1983年   200篇
  1982年   163篇
  1981年   145篇
  1980年   132篇
  1979年   98篇
  1978年   63篇
  1977年   66篇
  1976年   91篇
  1975年   38篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Pyrochlore-type WO_3 powder was synthesized via hydrothermal method using aqueous sodium tungstate solution and oxalic acid as raw materials. The as-prepared powder was made into a soliquoid,from which films were made by dip coating process with indium-tin oxide(ITO).The obtained films were characterized by thermogravimetric and differential thermal analysis(TG-DTA), X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM), cyclic voltammetry(CV), chronoamperometry(CA) and ultravioletvisible(UV-Vis) absorption. Results show that the crystal of the pyrochlore-type WO_3 powder is perfect. When the calcination temperature rises from room temperature to500 ℃,the pyrochlore-type structure first becomes deformed, then it is destroyed and turns into amorphous phase,finally it will completely convert to WO_3 with a monoclinic structure. Electrochemical and optical tests demonstrate that the film calcined at 300 ℃ exhibits the best electrochromic performance and has a coloration efficiency of up to 68.5 cm~2 C~(-1) at 884 nm.  相似文献   
102.
In this study, a simple hydrothermal synthesis method was adapted for the preparation of Co-doping Co2+/F-/TiO2 nanotubes photocatalyst, and the micro-nano structure of catalysts prepared by biomimetic technology which makes the catalyst have super-oleophilicity property. Co2+/F-/TiO2 revealed improved photocatalytic performance for denitrification of light oil compared to single TiO2 photocatalysts. The enhance of photocatalytic activity can be attributed to narrowing the band gap, increasing the light response wavelength and exposing more highly active crystal surfaces due to synergistic effects of Co2+ and F? in the photocatalyst.  相似文献   
103.
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being.  相似文献   
104.
105.
106.
107.
108.
109.
Rapid and sensitive point-of-care testing (POCT) is an extremely critical mission in practical applications, especially for rigorous military medicine, home health care, and in the third world. Here, we report a visual POCT method for adenosine triphosphate (ATP) detection based on Taylor rising in the corner of quadratic geometries between two rod surfaces. We discuss the principle of Taylor rising, demonstrating that it is significantly influenced by contact angle, surface tension, and density of the sample, which are controlled by ATP-dependent rolling circle amplification (RCA). In the presence of ATP, RCA reaction effectively suppresses Taylor-rising behavior, due to the increased contact angle, density, and decreased surface tension. Without addition of ATP, untriggered RCA reaction is favorable for Taylor rising, resulting in a significant height. With this proposed method, visual sensitive detection of ATP without the aid of other instruments is realized with only a 5 μL droplet, which has good selectivity and a low detection limit (17 nM). Importantly, this visual method provides a promising POCT tool for user-friendly molecular diagnostics.  相似文献   
110.
在国家政策和市场需求的双重推动下,BIM技术在国内建筑领域迎来快速发展阶段,从最初的概念普及,到能够局部应用,再到现在能够全过程应用,其趋势是十分明确的,但是在其发展的过程中仍然存在着不少问题,如传统技术与BIM技术深入融合问题,BIM技术如何解决工程施工现场实际问题等.本文主要研究BIM技术在连云港民用机场迁建工程旅客过夜用房酒店项目中的综合应用,从协同建模、碰撞检查、管线综合、施工图深化出图及漫游展示等方面着手,着重解决BIM技术在施工过程中应用的落地问题,从而达到提高效率,缩短工期,降低成本,提升质量的目标.  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