首页 | 官方网站   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   1517932篇
  免费   27756篇
  国内免费   6974篇
工业技术   1552662篇
  2021年   14682篇
  2020年   11893篇
  2019年   14712篇
  2018年   15790篇
  2017年   15044篇
  2016年   21497篇
  2015年   17363篇
  2014年   28761篇
  2013年   87901篇
  2012年   36671篇
  2011年   49482篇
  2010年   42830篇
  2009年   51033篇
  2008年   46063篇
  2007年   43465篇
  2006年   45989篇
  2005年   40475篇
  2004年   42659篇
  2003年   42454篇
  2002年   39146篇
  2001年   36271篇
  2000年   33829篇
  1999年   33782篇
  1998年   50210篇
  1997年   41608篇
  1996年   35841篇
  1995年   32035篇
  1994年   29770篇
  1993年   29529篇
  1992年   26146篇
  1991年   23475篇
  1990年   23741篇
  1989年   22636篇
  1988年   21314篇
  1987年   19455篇
  1986年   19045篇
  1985年   22449篇
  1984年   22378篇
  1983年   20385篇
  1982年   19217篇
  1981年   19296篇
  1980年   17964篇
  1979年   18555篇
  1978年   17715篇
  1977年   17885篇
  1976年   19422篇
  1975年   15957篇
  1974年   15514篇
  1973年   15592篇
  1972年   13138篇
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
101.
Rapid digestion and absorption of carbohydrates have become a health issue (high glycaemic index, GI), which can be a matter of greater concern when consumed in large quantities. Depending upon the influence of carbohydrates on the blood sugar levels, GI classifies carbohydrates (on a scale of 100) as low (<55), medium (55–70) and high (>70) GI foods. Among the pseudocereals, chia seed possesses relatively lower GI (28.53), as compared to buckwheat (52.35), amaranth (47.65) and quinoa (61.50). Consumers now prefer foods with a high GI over the ones with low GI to prevent various metabolic alterations. Celiac disease is a lifelong disorder prevalent worldwide and can only be controlled by following a strict lifelong gluten-free diet. Therefore, pseudocereals could be a potential alternate for low GI food and developing gluten-free food products, including bread, cookies, noodles and pasta. This review synthesises the recently published literatures on pseudocereals as a lowering GI and healthy food option. This review also gives insights into developing pseudocereals as a potential and novel ingredient for gluten-free food applications and the latest research conducted worldwide.  相似文献   
102.
103.
104.
Fire Technology - The directional flame thermometer (DFT) is a device used to measure radiative heat flux in fire scenarios. In many DFT applications, radiation is the dominant mode of heat...  相似文献   
105.
Soil Mechanics and Foundation Engineering - The present article describes a procedure for predicting the settlement of structures surrounding deep excavations in Vietnam that takes the...  相似文献   
106.
Russian Engineering Research - The role of tax administration in maximizing budget revenues at different levels is described. A significant proportion of tax payments consists of the settlement of...  相似文献   
107.

Hybrid organic–inorganic nanocomposites are great candidates for display and illumination systems due to improved optoelectronic properties and photostability. This work endeavours towards the scientific study of the influence of defect-induced zinc oxide nanoparticles (ZnO) on the optical characteristics of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). ZnO nanoparticles consist of many vacancies which facilitate light emission across the visible region. The green defective emission occurring due to the presence of oxygen vacancies in ZnO was used to re-excite MEH-PPV and hence, improve the luminescence quantum efficiency. The photostability of the nanocomposite was enhanced through charge transfer (prevents the formation of superoxides) and energy transfer (reduces the non-radiative decay) mechanisms.

Graphical abstract
  相似文献   
108.

The friction stir welded joint of wrought ZM21 alloy was divided into five parts, and their localized creep behavior was studied via the impression method. The tests were carried out in the stress range of 300–450 MPa (σimp/G ≈ 0.02–0.03) and in the temperature range of 448–523 K. Optical and SEM micrographs and EDS taken before and after the impression tests were used to study the microstructure of various zones of the FS welded joint. Power law was found to satisfactorily relate the stress and strain rates. The steady-state impression velocity was found to vary significantly between the advancing and retreating sides of TMAZ and HAZ. For TMAZ, the creep exponent on the AS was 4.8, and on the RS, it was 7.8. The activation energy on the AS was ~?133 kJ/mol, and on the RS, it was ~?101 kJ/mol. Similarly, for HAZ, the creep exponent on the AS was found to be 5.5 and on the RS, it was 4.9. The activation energy on the AS was ~?86 kJ/mol and on the RS, it was ~?232 kJ/mol. The cross-over of steady-state impression velocity of different zones indicates that the weak zone was temperature and stress dependent. Within the stresses and temperatures studied, the weld zone's creep resistance (i.e., lower minimum impression velocity) was found to be better than the base material. As it is with most magnesium alloys, dislocation climb was found to be the operative mechanism in the FS weldments of ZM21 alloy. The rate-controlling mechanism remains to be identified because the wide variation in n and Q values suggests that different creep mechanisms are in operation in different zones.

Graphical abstract
  相似文献   
109.
Telecommunication Systems - Energy saving in User Equipment (UE) is one of the important issues for limited sources of power in the device. It is critical for the UE to maximize its energy...  相似文献   
110.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  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-23

京公网安备 11010802026262号