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排序方式: 共有1368条查询结果,搜索用时 31 毫秒
1.
Wireless Personal Communications - In the present scenario, there is a boom in the demand of the users to achieve increased capacity, high data, low latency, and high-performance rates. 5G New... 相似文献
2.
Wireless Personal Communications - Now-a-days the most common pretentious disease is the lung cancer, which has become more prevalent in the world that primarily infects the pulmonary nodules of... 相似文献
3.
4.
Some substituted coumarins have been synthesized by von-Pechmann condensation using SnCl2 · 2H2O (10 mol %) as catalyst in ethanolic medium. The reactions are simple, easy in handling and environmentally benign. 相似文献
5.
R Albrecht TC Awes C Baktash P Beckmann F Berger R Bock G Claesson G Clewing L Dragon A Eklund RL Ferguson A Franz S Garpman R Glasow HA Gustafsson HH Gutbrod J Idh P Jacobs K Kampert BW Kolb P Kristiansson IY Lee H Loehner I Lund FE Obenshain A Oskarsson I Otterlund T Peitzmann S Persson F Plasil AM Poskanzer M Purschke H Ritter S Saini R Santo HR Schmidt T Siemiarczuk SP Sorensen E Stenlund ML Tincknell GR Young 《Canadian Metallurgical Quarterly》1991,44(6):2736-2752
6.
Arjunan Arulchakkaravarthi Rakesh Kumar Parthasarathy Santhanaraghavan Sivaramakrishnan Muralithar Rengasamy Gopalakrishanan Perumalsamy Ramasamy 《Materials Research Innovations》2002,6(5-6):273-276
Organic molecular scintillating crystals are noted for their good timing and particle discrimination process. Trans-stilbene
is one such candidate noted for its good particle detection characteristics for the past five decades. Progressive strengthening
of detection characteristics of trans-stilbene has been attempted by improving crystal perfection. A series of timing resolution
studies have been carried out for the Bridgman grown trans-stilbene crystals under different experimental conditions. The
results were compared with the previously reported values. Pulse shape discrimination process has been carried out for 241Am and 252Cf sources and good discrimination has been obtained for gamma-alpha and gamma-neutron sources from the grown organic phosphor
crystal.
Electronic Publication 相似文献
7.
Current desktop computers typically use fan-heat sinks for cooling the CPU, referred to as active heat sinks. This work seeks to determine the heat rejection limits for such fan-heat sinks, within specific fan and heat sink space limits. A fixed volume, 80 /spl times/ 60 /spl times/ 50 mm is chosen as the limiting dimensions, which includes the fan volume. The present work addresses plane fin heat sinks, on which a typical 60 mm fan is mounted. Both duct flow and impinging flow are considered. Analytically based models are used to predict the optimum geometry (minimum convection resistance) for plane fins with duct and impinging flow configurations. Also assessed are the effects of increased fan speed (up to 25%) and heat sink base size (33% increase) on air-cooling limits in duct and impinging flow. Tests on fan-heat sinks are done to validate the predictions. Optimization is also done for an enhanced (offset-strip) fin geometry in duct flow. The plane fin is found to outperform the enhanced geometry. 相似文献
8.
Changes in the NHS have supported the idea of targeting health services to those in greatest need. This has meant that health visitors are increasingly having to identify 'vulnerable' families in need of increased health visiting intervention. This paper reports on a qualitative study undertaken in order to explore the ways in which health visitors plan and organize their work in relation to the concept of vulnerability. Focus groups and semi-structured interviews were carried out with health visitors from two separate geographical areas, one an inner city area and the other suburban, in order to explore the criteria by which health visitors define vulnerability and decide to increase their levels of intervention to particular families. It was found that vulnerability was extremely difficult to define but that the health visitors used criteria which were appropriate to the particular localities in which they worked to identify vulnerable families and to increase their levels of intervention to those families. Health visitors were targeting their services within a framework of a basic minimum service to all and were assessing the health needs of individuals or families rather than planning their work on the basis of community or practice profiles. 相似文献
9.
In this paper, we have proposed some new numerical and semi-analytical methods for developing an equivalent three-layer model of an MQW waveguide. The waveguiding properties like effective index, field distribution, and fractional power within the core of the waveguide of these equivalent structures are compared with those of previously reported equivalent methods. These results are also compared with the results obtained from the exact multilayer analysis of the MQW waveguide. The waveguiding properties are accurately predicted by the semi-analytical method using variational analysis, and the computational effort is significantly reduced. The use of the three-layer equivalent is illustrated in obtaining an estimation of the waveguide losses and is used to study the effect of nonlinearity 相似文献
10.
Rakesh?Kumar?MahajanEmail author Inderpreet?Kaur Mandeep?Singh?Bakshi 《Journal of surfactants and detergents》2004,7(2):131-134
Poly(vinyl chloride) (PVC) membrane electrodes to determine monomer concentrations of tetradecyltrimethylammonium ion (TTA+) and hexadecylpyridinium ion (HPy+) based on neutral ion-pair carrier complexes of tetradecyltrimethylammonium dodecyl sulfate (TTA+-DS−) and hexadecylpyridinium dodecyl sulfate (HPy+-DS−), respectively, are reported here. The electrodes exhibit a Nernstian slope of 59 mV per decade for TTA+ and a sub-Nernstian slope of 34.5 mV per decade for HPy+ ions. The TTA+ ion-selective electrode (ISE) and the HPy+-ISE can determine the monomer units down to concentrations as low as 4.0×10−4M and 1.66×10−5 M, respectively. The effect of various additives, such as the anionic polyelectrolyte sodium dextran sulfate and macrocyclic
β-cyclodextrin, on the surface activity exhibited by the cationic surfactants TTA+-DS− and HPy+-DS−, in the presence of background concentrations of NaCl was also examined with surfactant-selective sensors. The Gibbs free
energy of micelle formation (ΔG
m
) of both surfactants in the presence of various additives was calculated and found to be less favorable with respect to an
increase in the amount of additives due to less availability of cationic surfactant monomer units. The ion-pair complexes
TTA+-DS− and HPy+-DS− were found to behave as selective carrier compounds in PVC membranes in determining the concentration of monomer units of
both TTA+ and HPy+, respectively. The proposed sensors worked well at a fairly acidic pH of 1–6.5 with response time of 60 s. The sensors responded
well to the surfactant ions even in the presence of additives at lower concentration. The lifetime of the sensors is 3 mon. 相似文献