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   1495563篇
  免费   27391篇
  国内免费   6950篇
电工技术   33841篇
综合类   6376篇
化学工业   254958篇
金属工艺   64189篇
机械仪表   42023篇
建筑科学   43523篇
矿业工程   11378篇
能源动力   49892篇
轻工业   110131篇
水利工程   15268篇
石油天然气   36600篇
武器工业   135篇
无线电   195926篇
一般工业技术   283604篇
冶金工业   179935篇
原子能技术   33955篇
自动化技术   168170篇
  2021年   14679篇
  2020年   11833篇
  2019年   14618篇
  2018年   15863篇
  2017年   15267篇
  2016年   21375篇
  2015年   17342篇
  2014年   28685篇
  2013年   88023篇
  2012年   35715篇
  2011年   48228篇
  2010年   42699篇
  2009年   51013篇
  2008年   45057篇
  2007年   42215篇
  2006年   44723篇
  2005年   39453篇
  2004年   41741篇
  2003年   41597篇
  2002年   39201篇
  2001年   35444篇
  2000年   33166篇
  1999年   33180篇
  1998年   48303篇
  1997年   40341篇
  1996年   35012篇
  1995年   31501篇
  1994年   29353篇
  1993年   29196篇
  1992年   25820篇
  1991年   23130篇
  1990年   23490篇
  1989年   22384篇
  1988年   20933篇
  1987年   19181篇
  1986年   18712篇
  1985年   21965篇
  1984年   22102篇
  1983年   20038篇
  1982年   19059篇
  1981年   19176篇
  1980年   17770篇
  1979年   18310篇
  1978年   17574篇
  1977年   17559篇
  1976年   19002篇
  1975年   15822篇
  1974年   15350篇
  1973年   15419篇
  1972年   12969篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Journal of Engineering Physics and Thermophysics - The possibility of intensifying the drying of materials by noncontact ultrasonic action at a frequency of 22 kHz at sound pressure levels up to...  相似文献   
102.
Yakunin  S. A. 《Radiochemistry》2022,64(4):482-490
Radiochemistry - As applied to the radioactive waste vitrification technology, published data on the behavior of cesium and its release into the gas phase are reviewed. The volatility of cesium...  相似文献   
103.
The aim of this study was to determine the effects of tumbling at different post-mortem times on the proteolytic features and quality attributes of beef loins (M. longissimus lumborum). Loins (n = 12) were cut into 4 sections and assigned to tumbling at 1, 6 or 11 days post-mortem or non-tumbled control. Upon tumbling, additional ageing was applied to a common post-mortem time of 16 days. In general, tumbling had no considerable impacts on water-holding ability of samples. Tumbling resulted in an immediate decrease in shear force values (WBSF) of beef samples. Tumbling at 1 day post-mortem with no ageing had similar WBSF compared to the non-tumbled controls at 16 days (P > 0.05). With ageing, tumbling increased amounts of protein degradation, myofibrillar fragmentation and calpain-1 autolysis of samples. These results suggest that early post-mortem tumbling coupled with ageing can synergistically impact the tenderness development of beef loins and shorten the necessary ageing period.  相似文献   
104.
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   
105.
106.
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   
107.
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   
108.
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   
109.

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   
110.

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   
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