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   232971篇
  免费   18244篇
  国内免费   9353篇
电工技术   12732篇
技术理论   24篇
综合类   14618篇
化学工业   39524篇
金属工艺   13410篇
机械仪表   14827篇
建筑科学   17845篇
矿业工程   7746篇
能源动力   6555篇
轻工业   13689篇
水利工程   3680篇
石油天然气   16794篇
武器工业   1678篇
无线电   25646篇
一般工业技术   27729篇
冶金工业   13024篇
原子能技术   2287篇
自动化技术   28760篇
  2024年   1006篇
  2023年   3836篇
  2022年   6535篇
  2021年   9192篇
  2020年   7137篇
  2019年   6080篇
  2018年   6822篇
  2017年   7627篇
  2016年   6867篇
  2015年   8999篇
  2014年   11420篇
  2013年   13448篇
  2012年   14412篇
  2011年   15662篇
  2010年   13646篇
  2009年   12927篇
  2008年   12628篇
  2007年   12066篇
  2006年   12561篇
  2005年   10940篇
  2004年   7469篇
  2003年   6547篇
  2002年   5914篇
  2001年   5322篇
  2000年   5633篇
  1999年   6606篇
  1998年   5514篇
  1997年   4517篇
  1996年   4239篇
  1995年   3544篇
  1994年   2856篇
  1993年   1988篇
  1992年   1569篇
  1991年   1240篇
  1990年   946篇
  1989年   749篇
  1988年   545篇
  1987年   337篇
  1986年   280篇
  1985年   198篇
  1984年   140篇
  1983年   115篇
  1982年   125篇
  1981年   104篇
  1980年   72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 0 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