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   107135篇
  免费   9103篇
  国内免费   4568篇
电工技术   5744篇
技术理论   9篇
综合类   6563篇
化学工业   18289篇
金属工艺   6277篇
机械仪表   7222篇
建筑科学   8173篇
矿业工程   3121篇
能源动力   2997篇
轻工业   6625篇
水利工程   1841篇
石油天然气   6689篇
武器工业   764篇
无线电   12347篇
一般工业技术   13621篇
冶金工业   5624篇
原子能技术   1307篇
自动化技术   13593篇
  2024年   371篇
  2023年   1880篇
  2022年   2780篇
  2021年   4521篇
  2020年   3341篇
  2019年   2964篇
  2018年   3199篇
  2017年   3418篇
  2016年   3154篇
  2015年   4137篇
  2014年   5227篇
  2013年   6258篇
  2012年   6585篇
  2011年   7325篇
  2010年   6203篇
  2009年   6028篇
  2008年   5845篇
  2007年   5490篇
  2006年   5704篇
  2005年   4891篇
  2004年   3445篇
  2003年   3233篇
  2002年   3184篇
  2001年   2901篇
  2000年   2733篇
  1999年   2873篇
  1998年   2381篇
  1997年   2008篇
  1996年   1863篇
  1995年   1504篇
  1994年   1231篇
  1993年   881篇
  1992年   694篇
  1991年   554篇
  1990年   450篇
  1989年   375篇
  1988年   261篇
  1987年   176篇
  1986年   144篇
  1985年   97篇
  1984年   79篇
  1983年   74篇
  1982年   68篇
  1981年   53篇
  1980年   38篇
  1979年   29篇
  1978年   20篇
  1976年   31篇
  1975年   14篇
  1973年   17篇
排序方式: 共有10000条查询结果,搜索用时 468 毫秒
1.
Zhao  Jiandong  Lei  Wei  Li  Zijian  Zhao  Dongfeng  Han  Mingmin  Hou  Xiaoqing 《Multimedia Tools and Applications》2022,81(4):4753-4780
Multimedia Tools and Applications - The crowding in bus is an important factor affecting passenger satisfaction and bus dispatching level. However, how to use video images to detect crowding...  相似文献   
2.
3.
The effects of high-pressure-modified soy 11S globulin (0.1, 200, and 400 MPa) on the gel properties, water-holding capacity, and water mobility of pork batter were investigated. The high-pressure-modified soy 11S globulin significantly increased (P < 0.05) the emulsion stability, cooking yield, hardness, springiness, chewiness, resilience, cohesiveness, the a* and b* values, and the G′ and G′′ values of pork batter at 80 °C, compared with those of 0.1 MPa-modified globulin. In contrast, the centrifugal loss and initial relaxation time of T2b, T21, and T22 significantly decreased (P < 0.05). Meanwhile, the microstructure was denser, and the voids were smaller and more uniform compared with those of 0.1 MPa-modified globulin. In addition, the sample with 11S globulin modified at 400 MPa had the best water-holding capacity, gel structure, and gel properties among the samples. Overall, the use of high-pressure-modified soy 11S globulin improved the gel properties and water-holding capacity of pork batter, especially under 400 MPa.  相似文献   
4.
Yang  Annan  Li  Bo  Yang  Mao  Yan  Zhongjiang  Xie  Yi 《Wireless Networks》2021,27(1):809-823
Wireless Networks - In this paper, a grouping-based uplink orthogonal frequency division multiple access (OFDMA) random access method is studied which can improve users’ satisfaction in the...  相似文献   
5.
6.
7.
8.
A digital light processing (DLP) technology has been developed for 3D printing lead-free barium titanate (BTO) piezoelectric ceramics. By comparing the curing and rheological properties of slurries with different photosensitive monomer, a high refractive index monomer acryloyl morpholine (ACMO) was chosen, and a design and preparation method of BTO slurry with high solid content, low viscosity and high curing ability was proposed. By further selecting the printing parameters, the single-layer exposure time was reduced and the forming efficiency has been greatly improved. Sintered specimens were obtained after a nitrogen-air double-step debinding and furnace sintering process, and the BTO ceramics fabricated with 80 wt% slurry shows the highest relative density (95.32 %) and piezoelectric constant (168.1 pC/N). Furthermore, complex-structured BTO ceramics were prepared, impregnated by epoxy resin and finally assembly made into hydrophones, which has significance for the future design and manufacture of piezoelectric ceramic-based composites that used in functional devices.  相似文献   
9.
To provide a basis for the high-temperature oxidation of ultra-high temperature ceramics (UHTCs), the oxidation behavior of Zr3[Al(Si)]4C6 and a novel Zr3[Al(Si)]4C6-ZrB2-SiC composite at 1500 °C were investigated for the first time. From the calculation results, the oxidation kinetics of the two specimens follow the oxidation dynamic parabolic law. Zr3[Al(Si)]4C6 exhibited a thinner oxide scale and lower oxidation rate than those of the composite under the same conditions. The oxide scale of Zr3[Al(Si)]4C6 exhibited a two-layer structure, while that of the composite exhibited a three-layer structure. Owing to the volatilization of B2O3 and the active oxidation of SiC, a porous oxide layer formed in the oxide scale of the composite, resulting in the degradation of its oxidation performance. Furthermore, the cracks and defects in the oxide scale of the composite indicate that the reliability of the oxide scale was poor. The results support the service temperature of the obtained ceramics.  相似文献   
10.
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection.  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