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   289464篇
  免费   6978篇
  国内免费   2435篇
电工技术   6868篇
技术理论   8篇
综合类   3273篇
化学工业   47913篇
金属工艺   12059篇
机械仪表   10606篇
建筑科学   9132篇
矿业工程   3099篇
能源动力   6572篇
轻工业   27547篇
水利工程   3253篇
石油天然气   8932篇
武器工业   474篇
无线电   30293篇
一般工业技术   50604篇
冶金工业   47701篇
原子能技术   6438篇
自动化技术   24105篇
  2022年   2752篇
  2021年   4069篇
  2020年   2998篇
  2019年   3339篇
  2018年   4968篇
  2017年   5064篇
  2016年   5140篇
  2015年   4163篇
  2014年   6258篇
  2013年   13062篇
  2012年   9067篇
  2011年   11586篇
  2010年   9297篇
  2009年   9901篇
  2008年   10336篇
  2007年   10217篇
  2006年   9476篇
  2005年   8318篇
  2004年   7243篇
  2003年   6940篇
  2002年   6886篇
  2001年   6653篇
  2000年   6585篇
  1999年   6721篇
  1998年   13669篇
  1997年   9823篇
  1996年   7686篇
  1995年   6081篇
  1994年   5356篇
  1993年   5089篇
  1992年   4022篇
  1991年   3644篇
  1990年   3806篇
  1989年   3618篇
  1988年   3434篇
  1987年   2976篇
  1986年   2988篇
  1985年   3402篇
  1984年   3243篇
  1983年   2913篇
  1982年   2760篇
  1981年   2835篇
  1980年   2730篇
  1979年   2628篇
  1978年   2685篇
  1977年   2948篇
  1976年   3805篇
  1975年   2368篇
  1974年   2242篇
  1973年   2376篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Feng  Wenran  Li  Zhen  Chen  Yingying  Chen  Jinyang  Lang  Haoze  Wan  Jianghong  Gao  Yan  Dong  Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in...  相似文献   
2.
3.
4.
Multimedia Tools and Applications - In geometry-based point cloud compression, the geometry information is typically compressed using octree coding. In octree coding, the size of the blocks in the...  相似文献   
5.
This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some.  相似文献   
6.
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   
7.
Journal of Communications Technology and Electronics - A statistical study of the effectiveness of the non-threshold search procedure for a noise-like phase-shift keyed signal by the delay time is...  相似文献   
8.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the...  相似文献   
9.
Journal of Inorganic and Organometallic Polymers and Materials - In this work, a borosilicate glass sample (5SiO2–45B2O3–20Na2O–25CaO–5Ag2O) was added to nano-sized...  相似文献   
10.
Mercury, lead, and cadmium are among the most toxic and carcinogenic heavy metal ions (HMIs), posing serious threats to the sustainability of aquatic ecosystems and public health. There is an urgent need to remove these ions from water by a cheap but green process. Traditional methods have insufficient removal efficiency and reusability. Structurally robust, large surface-area adsorbents functionalized with high-selectivity affinity to HMIs are attractive filter materials. Here, an adsorbent prepared by vulcanization of polyacrylonitrile (PAN), a nitrogen-rich polymer, is reported, giving rise to PAN-S nanoparticles with cyclic π-conjugated backbone and electronic conductivity. PAN-S can be coated on ultra-robust melamine (ML) foam by simple dipping and drying. In agreement with hard/soft acid/base theory, N- and S-containing soft Lewis bases have strong binding to Hg2+, Pb2+, Cu2+, and Cd2+, with extraordinary capture efficiency and performance stability. Furthermore, the used filters, when collected and electrochemically biased in a recycling bath, can release the HMIs into the bath and electrodeposit on the counter-electrode as metallic Hg0, Pb0, Cu0, and Cd0, and the PAN-S@ML filter can then be reused at least 6 times as new. The electronically conductive PAN-S@ML filter can be fabricated cheaply and holds promise for scale-up applications.  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