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   206262篇
  免费   18041篇
  国内免费   10085篇
电工技术   12390篇
技术理论   18篇
综合类   15263篇
化学工业   33258篇
金属工艺   11569篇
机械仪表   13143篇
建筑科学   15725篇
矿业工程   6073篇
能源动力   5670篇
轻工业   17249篇
水利工程   4026篇
石油天然气   12381篇
武器工业   1610篇
无线电   23047篇
一般工业技术   23536篇
冶金工业   9305篇
原子能技术   2264篇
自动化技术   27861篇
  2024年   834篇
  2023年   3390篇
  2022年   6204篇
  2021年   8743篇
  2020年   6719篇
  2019年   5311篇
  2018年   5992篇
  2017年   6828篇
  2016年   5928篇
  2015年   8471篇
  2014年   10697篇
  2013年   12898篇
  2012年   13912篇
  2011年   15263篇
  2010年   13476篇
  2009年   12451篇
  2008年   12458篇
  2007年   11802篇
  2006年   11386篇
  2005年   9660篇
  2004年   6592篇
  2003年   5768篇
  2002年   5657篇
  2001年   4866篇
  2000年   4375篇
  1999年   4642篇
  1998年   3633篇
  1997年   2999篇
  1996年   2919篇
  1995年   2343篇
  1994年   1916篇
  1993年   1398篇
  1992年   1140篇
  1991年   828篇
  1990年   654篇
  1989年   522篇
  1988年   423篇
  1987年   296篇
  1986年   212篇
  1985年   170篇
  1984年   131篇
  1983年   73篇
  1982年   95篇
  1981年   69篇
  1980年   65篇
  1979年   37篇
  1977年   16篇
  1976年   15篇
  1959年   11篇
  1951年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 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.
Mobile Networks and Applications - Inverse kinematics is an important basic theory in walking control of biped robot. This study focuses on the parameter setting using the improved algorithm in...  相似文献   
3.
Tang  Haina  Zhao  Xiangpeng  Ren  Yongmao 《Wireless Networks》2022,28(3):1197-1202
Wireless Networks - Geolocation is important for many emerging applications such as disaster management and recommendation system. In this paper, we propose a multilayer recognition model (MRM) to...  相似文献   
4.
5.
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP.  相似文献   
6.
熊小明  赵静 《电信科学》2022,38(11):163-168
基于电信运营商数字化转型,系统性地提出了数据驱动的云网发展规划体系,以及六大关键数字化能力构建,设计和实现了一种云网规划数字化平台,该平台可用于实现目标网络精细规划、边缘计算精准预测等场景,并探讨了数字孪生在规划领域的应用前景,对运营商推进云网融合战略、推进高质量发展具有指导和参考意义。  相似文献   
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.
Hydraulic fracturing with slickwater is a field-proven stimulation technology used in tight reservoirs. Because of the high pumping rate associated with slickwater fracturing, drag reduction (DR) is critical in minimizing pressure drop and the success of oilfield operations. In this paper, a new type of drag reducer (SPR) was synthesized with acrylamide and 12-allyloxydodecyl acid sodium, and its drag reduction performance was evaluated. The results showed that the new drag reducer features low molecular weight, fast-dissolving rate and low interfacial tension. The algorithm of estimating the drag reduction rate of non-Newtonian fluid SPR was proposed and validated. Empirical or semianalytical models for estimating the friction ratio (σ) or friction factor (λ or f) were used to simulate the turbulence behavior of the SPR drag reducer under different Reynolds numbers (Re). The modified Virk's correlation could accurately model the turbulent behavior of the SPR drag reducer. A unified calculation formula was established in this study for different pipe diameters.  相似文献   
10.
Sun  Junli  Wang  Huaibin  Li  Yang  Zhao  Min 《Journal of Porous Materials》2021,28(3):889-894
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple...  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