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   2866篇
  免费   121篇
  国内免费   18篇
电工技术   40篇
综合类   2篇
化学工业   574篇
金属工艺   69篇
机械仪表   104篇
建筑科学   49篇
矿业工程   2篇
能源动力   175篇
轻工业   179篇
水利工程   15篇
石油天然气   7篇
无线电   398篇
一般工业技术   611篇
冶金工业   314篇
原子能技术   27篇
自动化技术   439篇
  2024年   9篇
  2023年   52篇
  2022年   114篇
  2021年   149篇
  2020年   119篇
  2019年   100篇
  2018年   147篇
  2017年   126篇
  2016年   124篇
  2015年   69篇
  2014年   113篇
  2013年   211篇
  2012年   120篇
  2011年   149篇
  2010年   121篇
  2009年   91篇
  2008年   95篇
  2007年   110篇
  2006年   65篇
  2005年   60篇
  2004年   44篇
  2003年   49篇
  2002年   56篇
  2001年   39篇
  2000年   29篇
  1999年   40篇
  1998年   78篇
  1997年   68篇
  1996年   47篇
  1995年   34篇
  1994年   27篇
  1993年   37篇
  1992年   15篇
  1991年   19篇
  1990年   15篇
  1989年   15篇
  1988年   14篇
  1987年   16篇
  1986年   16篇
  1985年   11篇
  1984年   19篇
  1983年   15篇
  1982年   8篇
  1981年   16篇
  1980年   14篇
  1979年   13篇
  1978年   13篇
  1977年   17篇
  1976年   26篇
  1973年   11篇
排序方式: 共有3005条查询结果,搜索用时 15 毫秒
1.
Laser ablation of high-temperature ceramic coatings results in thermal residual stresses due to which the coatings fail by cracking and debonding. Hence, the measurement of such residual stresses during laser ablation process holds utmost importance from the view of performance of coatings in extreme conditions. The present research aims at investigating the effect of laser parameters such as laser pulse energy, scanning speed and line spacing on thermal residual stresses induced in tantalum carbide-coated graphite substrates. Residual stresses were measured using micro-Raman spectroscopy and correlated with Raman peak shifts. Transient thermal analysis was performed using COMSOL Multiphysics to model the single ablated track and residual stresses were reported at low, moderate and high pulse energy regimes. The results showed that the initial laser conditions caused higher tensile residual stresses. Moderate pulse energy regime comprised higher compressive residual stresses due to off centre overlapping of the laser pulses. Higher pulse energy (250 μJ), higher scanning speed (1000 mm/s) and moderate line spacing (20 μm) caused accumulation of tensile residual stresses during the final stage of laser ablation. The deviation of experimental residual stresses from COMSOL numerical model was attributed to unaccounted additional stresses induced during thermal spraying process and deformation potentials in the numerical model.  相似文献   
2.
3.
The Journal of Supercomputing - In the last decade, cloud computing has brought enormous changes to people’s lives. Cloud computing gives a client-driven computational model. In this case,...  相似文献   
4.
Neural Computing and Applications - The identification of water stress is a major challenge for timely and effective irrigation to ensure global food security and sustainable agriculture. Several...  相似文献   
5.
In India, little attention has been paid on antimicrobial resistance (AMR) in the context of developing “One Health” approach. Hence, utilizing multi-disciplinary approach, we assess the AMR level and dynamics/pattern of multi-drug resistance (MDR) in Escherichia coli, Salmonella spp., and Staphylococcus aureus circulating over the different stages of poultry in India. A total of 342 isolates including E. coli (n = 143), Salmonella spp. (n = 104), and S. aureus (n = 95) were recovered from fecal (n = 80) and cecal (n = 80) samples of chicken, collected across the different poultry-retail shops and poultry-farms located at urban and rural areas of Rajasthan, India, respectively. High rates of AMR to drugs that are critically/highly important both in human and veterinary medicine were observed among all the isolates. Upward trends in AMR prevalence was observed in poultry-retail shops than in poultry-farms. Notably, >90% of all the isolates were MDR, of particular, pattern/prevalence of MDR was substantially varied across the poultry-farms vs. poultry-retail shops. Our results indicate AMR including MDR to be common in E. coli, Salmonella spp., and S. aureus distributed frequently in poultry. The study encourages the formulation of national policy, programmes and further research with a “One Health” approach that can benefits to the human/animal and the environment.  相似文献   
6.
7.
8.
The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General Motors Corporation is reviewed.  相似文献   
9.
The application of micro- and nanofabrication processes to the development of hybrid synthetic and biological systems may enable the production of new devices such as controllable transporters, gears, levers, micropumps, or microgenerators powered by biological molecular motors. However, engineering these hybrid devices requires fabrication processes that are compatible with biological materials such as kinesin motor proteins and microtubules. In this paper, the effects of micro- and nanofabrication processing chemicals and resists on the functionality of casein, kinesin, and microtubule proteins are systematically examined to address the important missing link of the biocompatibility of micro- and nanofabrication processes needed to realize hybrid system fabrication. It is found that both casein, which is used to prevent motor denaturation on surfaces, and kinesin motors are surprisingly tolerant of most of the processing chemicals examined. Microtubules, however, are much more sensitive. Exposure to the processing chemicals leads to depolymerization, which is partially attributed to the pH of the solutions examined. When the chemicals were diluted in aqueous buffers, a subset of them no longer depolymerized microtubules and in their diluted forms still worked as resist removers. This approach broadens the application of micro- and nanofabrication processes to hybrid synthetic and biological system fabrication.  相似文献   
10.
A simple practical equivalent continuum numerical model for simulating the behavior of jointed rock mass has been extended to three-dimensional using FLAC3D. This model estimates the properties of jointed rock mass from the properties of intact rock and a joint factor (Jf), which is the integration of the properties of joints to take care of the effects of frequency, orientation, and strength of joint. A new FISH function has been written in FLAC3D specifically for modeling jointed rocks using the Duncan and Chang hyperbolic model. This model has been validated first with simple element tests at different confining pressures for different rocks with different joint configurations. Explicit modeling of the joints has also been done in element tests and results obtained compare well with the results of equivalent continuum model and also with experimental results. Further, this has been applied for a case study of a large underground power house cavern in the Himalayas. The analysis has been done under various stages of excavation, assigning a null model available in FLAC3D for simulating the excavation.  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