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   228462篇
  免费   17910篇
  国内免费   9140篇
电工技术   12463篇
技术理论   24篇
综合类   14156篇
化学工业   38796篇
金属工艺   13140篇
机械仪表   14523篇
建筑科学   17569篇
矿业工程   7508篇
能源动力   6421篇
轻工业   13442篇
水利工程   3589篇
石油天然气   16618篇
武器工业   1652篇
无线电   25143篇
一般工业技术   27334篇
冶金工业   12809篇
原子能技术   2247篇
自动化技术   28078篇
  2024年   996篇
  2023年   3801篇
  2022年   6486篇
  2021年   9094篇
  2020年   7081篇
  2019年   6010篇
  2018年   6732篇
  2017年   7544篇
  2016年   6748篇
  2015年   8866篇
  2014年   11250篇
  2013年   13277篇
  2012年   14213篇
  2011年   15444篇
  2010年   13419篇
  2009年   12683篇
  2008年   12344篇
  2007年   11846篇
  2006年   12338篇
  2005年   10746篇
  2004年   7258篇
  2003年   6228篇
  2002年   5465篇
  2001年   4884篇
  2000年   5437篇
  1999年   6437篇
  1998年   5437篇
  1997年   4456篇
  1996年   4191篇
  1995年   3500篇
  1994年   2816篇
  1993年   1965篇
  1992年   1537篇
  1991年   1226篇
  1990年   934篇
  1989年   741篇
  1988年   538篇
  1987年   336篇
  1986年   278篇
  1985年   196篇
  1984年   140篇
  1983年   114篇
  1982年   124篇
  1981年   98篇
  1980年   70篇
  1979年   36篇
  1978年   26篇
  1977年   20篇
  1976年   35篇
  1973年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation.  相似文献   
52.
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   
53.
54.
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   
55.
56.
57.
58.
59.
60.
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