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   263篇
  免费   14篇
电工技术   2篇
化学工业   69篇
金属工艺   4篇
机械仪表   8篇
建筑科学   1篇
矿业工程   1篇
能源动力   3篇
轻工业   4篇
水利工程   1篇
无线电   53篇
一般工业技术   54篇
冶金工业   10篇
原子能技术   2篇
自动化技术   65篇
  2022年   6篇
  2021年   6篇
  2020年   5篇
  2019年   7篇
  2018年   6篇
  2017年   5篇
  2016年   8篇
  2015年   3篇
  2014年   12篇
  2013年   18篇
  2012年   21篇
  2011年   30篇
  2010年   15篇
  2009年   9篇
  2008年   13篇
  2007年   15篇
  2006年   8篇
  2005年   13篇
  2004年   9篇
  2003年   6篇
  2002年   5篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   1篇
  1997年   4篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1993年   4篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1989年   6篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1984年   1篇
  1983年   1篇
  1982年   4篇
  1980年   2篇
  1978年   4篇
  1977年   1篇
  1976年   2篇
  1971年   1篇
  1969年   1篇
  1967年   3篇
排序方式: 共有277条查询结果,搜索用时 31 毫秒
41.

Today, cities face many significant challenges, and the smart city concept is a promising means to address typical traditional city problems. The wireless e-health technologies is an evolving topic in the area of telemedicine nowadays. Mobile telecommunication and the use of multimedia technologies are the core of providing better access to healthcare personnel on the move. These technologies provide equal access to medical information and expert care leading to a better and a more efficient use of resources. Mobile and Fog computing technologies can also cope with many challenges in smart healthcare resources of mobility, scalability, efficiency, and reliability. Optimal healthcare systems are particularly critical in cities, due to the highly concentrated populations. This high population increases the potential for harm and damage in the case of negligence or improper treatment. This can lead to infections and disease outbreaks, which could become epidemic situations and require containment, which is very costly. Motivated by the need for better usage and management of healthcare resources, which is crucial for reliable healthcare delivery, this paper introduces a model that can provide improved delivery and utilization of resources. The quality reward-based model was developed to study and react to the satisfaction factors of healthcare systems, and proposes an optimization-based algorithm called the Maximum Reward Algorithm (MRA), that enhances the use and delivery of healthcare resources. The algorithm has been tested with multiple experiments and simulations, and has proved that it can provide reliability, efficiency and achieves 50.1% to 77.2% performance improvement.

  相似文献   
42.
A first order irreversible reaction is investigated using a stochastic model in order to account for the perturbations inherent to any chemical process. The main conclusion is that the concentration is distributed according to a lognormal law rather than to a normal one. This approach leads to a maximum likelihood estimate of the kinetic constant which is different with respect to the usual least squares estimate. Moreover, the stochastic model allows us to predict not only the expected value of the concentration, but to get a confidence interval, too. Statistical tests are provided in order to detect outliers, high-leverage and influential points.  相似文献   
43.
44.
We have measured the temperature and polarization dependence of Silin spin wave spectra in a saturated 3He–4He mixture with a concentration of 9.4% at a pressure of 8 bars. The mixture has been cooled and polarized by a Leiden dilution refrigerator to temperatures in the range 10–15 mK and polarizations as high as 9.2% corresponding to 3.4 times the equilibrium polarization of 2.7% in the external magnetic field of 11.36 T. The analysis takes into account the dipolar interactions and results in the relaxation time τ and spin diffusion constant D . We find that τ and D are proportional to where T is the temperature, is the polarization enhancement factor and T a0 is the anisotropy temperature for the mixture at equilibrium in the external field. Our result T a0=3.66±0.14 mK is 30% higher than the theoretical prediction for very dilute mixtures and is evidence for the existence of polarization induced relaxation of transverse spin currents.  相似文献   
45.
We demonstrate that arrays of nanowires of conjugated polymers can be easily produced by a simple embossing protocol, compatible with very large scale integration technology. The embossing process is shown to have the supplementary virtue to increase the internal degree of order of the nanowires, significantly enhancing their performance. This is applied to the fabrication of nanowire-based devices consisting of a liquid crystalline light-emitting polymer, of a liquid crystalline semiconducting polymer, and of an amorphous conducting polymer, illustrating the versatility and wide applicability of the method.  相似文献   
46.
Post-growth transfer and high growth temperature are two major hurdles that research has to overcome to get graphene out of research laboratories. Here, using a plasma-enhanced chemical vapour deposition process, we demonstrate the large-area formation of continuous transparent graphene layers at temperatures as low as 450?°C. Our few-layer graphene grows at the interface between a pre-deposited 200 nm Ni catalytic film and an insulating glass substrate. After nickel etching, we are able to measure the optical transmittance of the layers without any transfer. We also measure their sheet resistance directly and after inkjet printing of electrical contacts: sheet resistance is locally as low as 500 Ω sq?1. Finally the samples equipped with printed contacts appear to be efficient humidity sensors.  相似文献   
47.
A simple explicit photovoltaic formulation for characterizing and dimensioning cell-arrays is presented. The method permits the short-circuit current, the open-circuit voltage, the maximum cell power and the optimum cell-operation conditions to be determined. Further, the model also allows quantifying the effects of panel temperature and solar irradiance on key cell parameters. Based on several datasheets, the methodology is validated by covering a wide range of operation conditions. The proposed approach can thus, be very useful for design engineers to quickly and easily determine the performance of any photovoltaic array without performing tedious numerical calculations.  相似文献   
48.
This paper presents a study of the effect of the low temperature atmospheric helium dielectric barrier discharge(DBD) on the Streptococcus mutans biofilms formed on tooth surface. Pig jaws were also treated by plasma to detect if there is any harmful effect on the gingiva.The plasma was characterized by using optical emission spectroscopy.Experimental data indicated that the discharge is very effective in deactivating Streptococcus mutans biofilms.It can destroy them with an average decimal reduction time(D-time) of 19 s and about 98%of thein were killed after a treatment time of 30 s.According to the survival curve kinetic an overall 32 s treatment time would be necessary to perform a complete sterilization.The experimental results presented in this study indicated that the helium dielectric barrier discharge,in plan-parallel electrode configuration,could be a very effective tool for deactivation of oral bacteria and might be a promising technique in various dental clinical applications.  相似文献   
49.
We report on the changes on the microstructural, hardness, and corrosion properties induced by carbo-chromization of 316L stainless steel prepared by Spark Plasma Sintering technique. The thermo-chemical treatments have been performed using pack cementation. The carburizing and chromization were carried out between 1153 K (880 °C)/4 h to 1253 K (980 °C)/12 h and 1223 K (950 °C)/6 h to 1273 K (1000 °C)/12 h in a solid powder mixture of charcoal/BaCO3 and ferrochromium/alumina/NH4Cl, respectively. The obtained layers were investigated using X-ray and electron diffraction, optical and scanning electron microscopies, Vickers micro-hardness, and potentiodynamic measurements. The thickness of the carbo-chromized layer ranges between 300 and 500 μm. Besides the host γ-phase, the layers are mainly constituted of carbides (Fe7C3, Cr23C6, Cr7C3, and Fe3C) and traces of α′-martensite. The average hardness values decrease smoothly from 650 HV at the sample surface down to 200 HV at the center of the sample. The potentiodynamic tests revealed that the carbo-chromized samples have smaller corrosion resistance with respect to the untreated material. For strong chromization regimes, the corrosion rate is increased by a factor of four with respect to that of the untreated material, while the micro-hardness of the layer is three times larger. Such materials are suited to be used in environments where good corrosion resistance and wear properties are required.  相似文献   
50.
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