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   229778篇
  免费   18111篇
  国内免费   9214篇
电工技术   12628篇
技术理论   24篇
综合类   14236篇
化学工业   39021篇
金属工艺   13352篇
机械仪表   14595篇
建筑科学   17662篇
矿业工程   7557篇
能源动力   6471篇
轻工业   13519篇
水利工程   3616篇
石油天然气   16698篇
武器工业   1666篇
无线电   25268篇
一般工业技术   27480篇
冶金工业   12864篇
原子能技术   2262篇
自动化技术   28184篇
  2024年   1012篇
  2023年   3869篇
  2022年   6607篇
  2021年   9243篇
  2020年   7167篇
  2019年   6062篇
  2018年   6787篇
  2017年   7615篇
  2016年   6791篇
  2015年   8931篇
  2014年   11328篇
  2013年   13371篇
  2012年   14321篇
  2011年   15555篇
  2010年   13484篇
  2009年   12741篇
  2008年   12394篇
  2007年   11891篇
  2006年   12390篇
  2005年   10774篇
  2004年   7292篇
  2003年   6245篇
  2002年   5468篇
  2001年   4897篇
  2000年   5455篇
  1999年   6447篇
  1998年   5439篇
  1997年   4464篇
  1996年   4204篇
  1995年   3511篇
  1994年   2822篇
  1993年   1976篇
  1992年   1539篇
  1991年   1232篇
  1990年   939篇
  1989年   743篇
  1988年   541篇
  1987年   339篇
  1986年   278篇
  1985年   200篇
  1984年   139篇
  1983年   115篇
  1982年   125篇
  1981年   101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