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   550篇
  免费   40篇
电工技术   17篇
综合类   4篇
化学工业   166篇
金属工艺   4篇
机械仪表   24篇
建筑科学   14篇
能源动力   18篇
轻工业   57篇
水利工程   1篇
石油天然气   6篇
无线电   55篇
一般工业技术   99篇
冶金工业   49篇
原子能技术   4篇
自动化技术   72篇
  2023年   7篇
  2022年   16篇
  2021年   33篇
  2020年   27篇
  2019年   29篇
  2018年   37篇
  2017年   31篇
  2016年   30篇
  2015年   29篇
  2014年   31篇
  2013年   54篇
  2012年   27篇
  2011年   28篇
  2010年   29篇
  2009年   17篇
  2008年   11篇
  2007年   13篇
  2006年   11篇
  2005年   14篇
  2004年   9篇
  2003年   5篇
  2002年   7篇
  2001年   7篇
  2000年   5篇
  1999年   5篇
  1998年   22篇
  1997年   14篇
  1996年   10篇
  1995年   2篇
  1994年   4篇
  1993年   8篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   3篇
  1980年   3篇
  1978年   1篇
  1973年   1篇
排序方式: 共有590条查询结果,搜索用时 15 毫秒
1.
Mobile Networks and Applications - Blockchain applications have continuously improved ever since its first debut on cryptocurrency. From then on, its uses have branched out from the financial...  相似文献   
2.
Spin-coated chalcostibite CuSbS2 thin films (≈500 nm thick) were fabricated and the influence of the drying temperature on the structural, morphological, optical and thermoelectric properties of the films was investigated. Crystalline phase-pure chalcostibite has been obtained for the films dried at 180 °C and 210 °C, while below 180 °C these films are partially amorphous. Surprisingly, at drying temperature of 240 °C, a CuxS secondary phase appeared. The increase of the drying temperature leads to the increase of the particle size and the decrease of the optical band gap, which is interesting for optoelectronic applications. The highest power factor value was achieved for the film dried at 210 °C, due to the inexistence of secondary phases, which allowed realizing a stable thermoelectric touch sensor with a Vsignal/noise of 5. In addition, this film was tested as a photovoltaic (PV) device and a power conversion efficiency (PCE) of 0.030% with an open-circuit voltage (VOC) of 0.36 V, a short-circuit current density (JSC) of 0.278 mAcm?2 and a fill factor (FF) of 0.27 were obtained. Therefore, this work evidences a pathway toward developing bi-functional devices with simultaneously thermoelectric touch sensor and photovoltaic functions.  相似文献   
3.
4.
Multimedia Tools and Applications - Disc herniation is considered as a very common spine abnormality resulting in severe pain in back and legs. Besides it has great impact on economy of suffering...  相似文献   
5.
6.
7.
8.
9.
The family Cactaceae is the diversified group of angiosperm plants whose pollen statistics has been used for taxonomic identification. In this article, we present the pollen morphology of eight species belong to seven taxonomically complex genera of Cactaceae including Astrophytum, Cylindropuntia, Echinocereus, Echinopsis, Mammillaria, Opuntia, and Thelocactus using light and scanning electron microscopy. The pollen grains were acetolyzed, measured, described, and electron photomicrographs were taken. Cactaceae can be characterized by presenting different palynomorphological features including pollen type, sculpturing, polar and equatorial diameter, aperture orientation, exine thickness, P/E ratio, and echini features. Four types of pollen shapes, that is, prolate spheroidal (three species), subprolate (two species), prolate (two species), and oblate spheroidal in Echinocereus reichenbachii were observed. The polar and equatorial diameter observed maximum in O. ficus indica 116.95 and 112.27 μm while minimum in M. compressa 38.42 and 21.05 μm. Pollen of two types, tricolpate in members of subfamily Cactioideae and pantoporate in the Opuntioideae were examined. The fertility percentage has been observed maximum in Opuntia macrocentra (83.84%) and minimum in Opuntia ficus‐indica (57.89%). Exine sculpturing showing great variations such as granulate, reticulate, granulate perforate and micro‐echinate foveolate ornamentation was examined only in Echinopsis eyriesii. A key to species, based on pollen micromorphological attributes, has been constructed for correct identification of complex cactus species.  相似文献   
10.
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