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   112953篇
  免费   15947篇
  国内免费   760篇
电工技术   2259篇
综合类   1000篇
化学工业   30542篇
金属工艺   3756篇
机械仪表   4774篇
建筑科学   3691篇
矿业工程   482篇
能源动力   3196篇
轻工业   11596篇
水利工程   1059篇
石油天然气   1833篇
武器工业   118篇
无线电   16867篇
一般工业技术   25771篇
冶金工业   8555篇
原子能技术   1581篇
自动化技术   12580篇
  2023年   663篇
  2022年   1234篇
  2021年   2185篇
  2020年   2688篇
  2019年   4222篇
  2018年   4645篇
  2017年   4946篇
  2016年   5613篇
  2015年   5391篇
  2014年   6167篇
  2013年   8806篇
  2012年   6448篇
  2011年   6851篇
  2010年   6056篇
  2009年   6144篇
  2008年   5442篇
  2007年   4862篇
  2006年   4319篇
  2005年   3651篇
  2004年   3554篇
  2003年   3444篇
  2002年   3623篇
  2001年   3024篇
  2000年   2601篇
  1999年   1814篇
  1998年   2387篇
  1997年   1627篇
  1996年   1379篇
  1995年   1108篇
  1994年   879篇
  1993年   834篇
  1992年   659篇
  1991年   688篇
  1990年   630篇
  1989年   647篇
  1988年   549篇
  1987年   504篇
  1986年   508篇
  1985年   488篇
  1984年   479篇
  1983年   421篇
  1982年   407篇
  1980年   387篇
  1978年   451篇
  1977年   458篇
  1976年   508篇
  1975年   409篇
  1974年   468篇
  1973年   436篇
  1972年   402篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Cases of isolated hepatic tuberculosis (TB) are rare. The diagnosis is often delayed or missed because of nonspecific symptoms and laboratory findings. Besides, the disease is extremely rare even in a country where TB is an alarming public health problem. This report demonstrates the difficulty in correctly diagnosing local hepatic TB. We report the case of a 62‐year‐old male patient with end‐stage renal disease treated with hemodialysis, who developed 2 months of abdominal distension and general anorexia, with hyperechoic hepatic lesions on ultrasound. Computed tomography suspected multiple liver tumors. The liver biopsy finally led to the diagnosis of TB of the liver without other involvements. We conclude that isolated hepatic TB is one of the rare forms of extrapulmonary TB in dialysis patients. A greater awareness of this rare clinical entity may prevent needless surgical interventions.  相似文献   
22.
23.
Cerebral microbleeds (CMBs) are small hemosiderin deposits indicative of prior cerebral microscopic hemorrhage and previously thought to be clinically silent. Recent population‐based cross‐sectional studies and prospective longitudinal cohort studies have revealed association between CMB and cognitive dysfunction. In the general population, CMBs are associated with age, hypertension, and cerebral amyloid angiopathy. In the chronic kidney disease (CKD) population, diminished estimated glomerular filtration rate has been found to be an independent risk factor for CMB, raising the possibility that a uremic milieu may predispose to microbleeds. In the end‐stage renal disease (ESRD) population on hemodialysis, the incidence of microbleeds is significantly higher compared with a control group without history of CKD or stroke. We present an ESRD patient on chronic hemodialysis with a history of gradual cognitive decline and progressive CMBs. Through this case and literature review, we illustrate the need to develop detection and prediction models to treat this frequent development in ESRD patients.  相似文献   
24.
25.
26.
27.
28.
Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria.  相似文献   
29.
The cover image is based on the Research Article V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .

  相似文献   

30.
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