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   2039篇
  免费   106篇
  国内免费   4篇
电工技术   16篇
综合类   3篇
化学工业   368篇
金属工艺   48篇
机械仪表   26篇
建筑科学   53篇
矿业工程   5篇
能源动力   68篇
轻工业   183篇
水利工程   7篇
石油天然气   8篇
无线电   318篇
一般工业技术   336篇
冶金工业   430篇
原子能技术   13篇
自动化技术   267篇
  2024年   3篇
  2023年   36篇
  2022年   35篇
  2021年   99篇
  2020年   71篇
  2019年   87篇
  2018年   76篇
  2017年   75篇
  2016年   111篇
  2015年   56篇
  2014年   83篇
  2013年   113篇
  2012年   97篇
  2011年   105篇
  2010年   88篇
  2009年   72篇
  2008年   78篇
  2007年   52篇
  2006年   39篇
  2005年   44篇
  2004年   28篇
  2003年   31篇
  2002年   33篇
  2001年   27篇
  2000年   28篇
  1999年   29篇
  1998年   114篇
  1997年   96篇
  1996年   56篇
  1995年   36篇
  1994年   33篇
  1993年   27篇
  1992年   18篇
  1991年   11篇
  1990年   12篇
  1989年   9篇
  1988年   11篇
  1987年   12篇
  1986年   8篇
  1985年   11篇
  1984年   5篇
  1983年   9篇
  1982年   13篇
  1981年   8篇
  1980年   5篇
  1979年   7篇
  1978年   7篇
  1977年   12篇
  1976年   24篇
  1972年   2篇
排序方式: 共有2149条查询结果,搜索用时 375 毫秒
81.
82.
83.
A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response.  相似文献   
84.
85.
Journal of Mechanical Science and Technology - In the present study, Electrically assisted (EA) stress relief annealing for automotive springs is experimentally investigated. A concept of EA stress...  相似文献   
86.
This paper presents a calculation method for obtaining the continuous variation in stress between the tip and the soil during dynamic penetration tests, particularly in the case of using the Panda 3® penetration testing device. The originality of the method is that the tip stress can be computed continuously throughout the driving process. For each impact of the hammer on the penetrometer, data are recorded by sensors located at the top of the apparatus. Then, the stress at the tip and the displacement of the apparatus are calculated with a method based on the propagation of waves in the device. A three-dimensional numerical model of the penetration test, based on the Panda 3® specifications and using the discrete element method (DEM), is proposed in this paper. The purpose of the simulations is to validate the calculation method by comparing the curves of the tip stress versus the penetration distance obtained in two different ways, the first being the distance directly observed at the tip and the second being the distance calculated from the data recorded at the top of the penetrometer, as with the experimental device. The entire apparatus is represented, including the hammer, the rod, and the tip, and is driven into the model soil. The calculation method is applied, and the results are compared to the actual response of the soil to the driving of the penetrometer directly at the tip, which can be obtained with the numerical model. The responses are found to be very similar, confirming the theoretical framework and its underlying assumptions. This method is applied to dynamic penetration tests and provides the opportunity to obtain mechanical parameters other than the tip resistance from the tests.  相似文献   
87.
Journal of Intelligent Information Systems - Nowadays, a vast amount of clinical data scattered across different sites on the Internet hinders users from finding helpful information for their...  相似文献   
88.
Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case–control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits.  相似文献   
89.
Mobile Networks and Applications - In this paper, we study the performance of a full-duplex (FD) relay system in vehicle-to-vehicle (V2V) communication. In this relay communication system, the...  相似文献   
90.
Vu  Thang X.  Trinh  Anh Vu  Chatzinotas  Symeon  Tran  Xuan Nam 《Wireless Networks》2020,26(6):4403-4410

Edge caching has received much attention as a promising technique to overcome the stringent latency and data-hungry challenges in the future generation wireless networks. Meanwhile, full-duplex (FD) transmission can potentially double the spectral efficiency by allowing a node to receive and transmit at the same frequency band simultaneously. In this paper, we investigate the delivery time performance of a cache-aided FD system, in which an edge node, operates in FD mode, serves users via wireless channels and is equipped with a cache memory. Firstly, we derive a closed-form expression for the average delivery time by taking into account the uncertainties of both backhaul and access wireless channels. The derived analysis allows the examination of the impact of key parameters, e.g., cache size and transmit power. Secondly, a power optimization problem is formulated to minimize the average delivery time. To deal with the non-convexity of the formulated problem, we propose an iterative optimization algorithm based on the bisection method. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm. A significant delivery time reduction is achieved by the proposed optimization compared to the FD reference and half-duplex counterpart.

  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