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   33225篇
  免费   1545篇
  国内免费   112篇
电工技术   421篇
综合类   232篇
化学工业   5845篇
金属工艺   678篇
机械仪表   688篇
建筑科学   1101篇
矿业工程   106篇
能源动力   1039篇
轻工业   4611篇
水利工程   283篇
石油天然气   165篇
武器工业   6篇
无线电   2393篇
一般工业技术   4740篇
冶金工业   7945篇
原子能技术   256篇
自动化技术   4373篇
  2024年   57篇
  2023年   178篇
  2022年   458篇
  2021年   903篇
  2020年   655篇
  2019年   720篇
  2018年   869篇
  2017年   943篇
  2016年   933篇
  2015年   688篇
  2014年   1029篇
  2013年   1748篇
  2012年   1530篇
  2011年   1830篇
  2010年   1352篇
  2009年   1427篇
  2008年   1254篇
  2007年   1159篇
  2006年   868篇
  2005年   926篇
  2004年   984篇
  2003年   895篇
  2002年   846篇
  2001年   725篇
  2000年   564篇
  1999年   605篇
  1998年   2595篇
  1997年   1619篇
  1996年   1139篇
  1995年   710篇
  1994年   557篇
  1993年   620篇
  1992年   237篇
  1991年   308篇
  1990年   240篇
  1989年   217篇
  1988年   233篇
  1987年   176篇
  1986年   177篇
  1985年   190篇
  1984年   135篇
  1983年   96篇
  1982年   126篇
  1981年   137篇
  1980年   129篇
  1979年   92篇
  1978年   80篇
  1977年   182篇
  1976年   348篇
  1975年   87篇
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
31.
32.
33.
34.
Personal and Ubiquitous Computing - This article presents a study concerning the evaluation of a smart home control system for elderly people with a sample of 10 users in a city in the interior of...  相似文献   
35.
36.
37.
An experimental methodology for inferring brine dissolution rate in monoethylene glycol (MEG) solutions at different temperatures using a webcam combined with a mathematical model is presented. The measurement system is designed to track the RGB (red, green, and blue) colour variations during the dissolution process. A dynamic model augmented with the population balance equation is applied to describe the dissolution process. Moreover, the dissolution rate is consistently related to the temperature and MEG concentration through the driving force based on the Gibbs energy and chemical affinity. The applied low-cost measurement apparatus proved to be a useful resource for tracking the dissolution dynamics in a wide range of undersaturation.  相似文献   
38.
39.

This paper presents a PVS development of relevant results of the theory of rings. The PVS theory includes complete proofs of the three classical isomorphism theorems for rings, and characterizations of principal, prime and maximal ideals. Algebraic concepts and properties are specified and formalized as generally as possible allowing in this manner their application to other algebraic structures. The development provides the required elements to formalize important algebraic theorems. In particular, the paper presents the formalization of the general algebraic-theoretical version of the Chinese remainder theorem (CRT) for the theory of rings, as given in abstract algebra textbooks, proved as a consequence of the first isomorphism theorem. Also, the PVS theory includes a formalization of the number-theoretical version of CRT for the structure of integers, which is the version of CRT found in formalizations. CRT for integers is obtained as a consequence of the general version of CRT for the theory of rings.

  相似文献   
40.
The association between obesity, cancer and cardiovascular disease (CVD) has been demonstrated in animal and epidemiological studies. However, the specific role of visceral obesity on cancer and CVD remains unclear. Visceral adipose tissue (VAT) is a complex and metabolically active tissue, that can produce different adipokines and hormones, responsible for endocrine-metabolic comorbidities. This review explores the potential mechanisms related to VAT that may also be involved in cancer and CVD. In addition, we discuss the shared pharmacological treatments which may reduce the risk of both diseases. This review highlights that chronic inflammation, molecular aspects, metabolic syndrome, secretion of hormones and adiponectin associated to VAT may have synergistic effects and should be further studied in relation to cancer and CVD. Reductions in abdominal and visceral adiposity improve insulin sensitivity, lipid profile and cytokines, which consequently reduce the risk of CVD and some cancers. Several medications have shown to reduce visceral and/or subcutaneous fat. Further research is needed to investigate the pathophysiological mechanisms by which visceral obesity may cause both cancer and CVD. The role of visceral fat in cancer and CVD is an important area to advance. Public health policies to increase public awareness about VAT’s role and ways to manage or prevent it are needed.  相似文献   
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