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   261732篇
  免费   30657篇
  国内免费   10103篇
电工技术   14607篇
技术理论   11篇
综合类   13869篇
化学工业   51154篇
金属工艺   13971篇
机械仪表   14816篇
建筑科学   16625篇
矿业工程   5530篇
能源动力   6142篇
轻工业   20529篇
水利工程   4867篇
石油天然气   12153篇
武器工业   1742篇
无线电   31051篇
一般工业技术   43273篇
冶金工业   13872篇
原子能技术   5607篇
自动化技术   32673篇
  2024年   1067篇
  2023年   3347篇
  2022年   6666篇
  2021年   9224篇
  2020年   8024篇
  2019年   8325篇
  2018年   9479篇
  2017年   10504篇
  2016年   10353篇
  2015年   11724篇
  2014年   13955篇
  2013年   17178篇
  2012年   16470篇
  2011年   17148篇
  2010年   15373篇
  2009年   15042篇
  2008年   14580篇
  2007年   13532篇
  2006年   12479篇
  2005年   10439篇
  2004年   8119篇
  2003年   7754篇
  2002年   7985篇
  2001年   7192篇
  2000年   6160篇
  1999年   4744篇
  1998年   3360篇
  1997年   2806篇
  1996年   2444篇
  1995年   2117篇
  1994年   1771篇
  1993年   1471篇
  1992年   1403篇
  1991年   1223篇
  1990年   1189篇
  1989年   1111篇
  1988年   972篇
  1987年   906篇
  1986年   803篇
  1985年   756篇
  1984年   722篇
  1981年   689篇
  1979年   743篇
  1978年   785篇
  1977年   749篇
  1976年   763篇
  1975年   721篇
  1974年   723篇
  1973年   726篇
  1972年   706篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo.  相似文献   
32.
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   
33.
34.
35.
36.
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   
37.
38.
39.
40.
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