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排序方式: 共有786条查询结果,搜索用时 15 毫秒
91.
Murali K. Akkapeddi 《Polymer》1979,20(10):1215-1216
The free radical copolymerization of α-methylene γ-butyrolactone (α-MBL, I) has been studied at 60°C, with methyl methacrylate, styrene, acrylamide, acrylonitrile and vinylene carbonate, respectively. The reactivity ratios thus determined generally establish the high reactivity of α-MBL as a comonomer. 相似文献
92.
J. W. Stephenson R. Manohar 《International journal for numerical methods in engineering》1979,14(9):1421-1427
It is shown here that certain interpolating polynomials of degrees four and five may not always be uniquely defined on triangular-shaped elements which have one curved side. Conditions which indicate non-uniqueness are given, together with some geometrical interpretations concerning the location of the node on the curved side. A numerical example is given to demonstrate that there ar curves for which every point is unsuitable to be chosen as a node. 相似文献
93.
94.
Effect of ferrocene concentration on the synthesis of bamboo-shaped carbon-nitrogen nanotube bundles
Yadav RM Shripathi T Srivastava A Srivastava ON 《Journal of nanoscience and nanotechnology》2005,5(5):820-824
We have investigated the effect of ferrocene concentration on the synthesis of carbon-nitrogen (C-N) nanotubes. The bamboo-shaped carbon-nitrogen nanotubes were synthesized by spray pyrolysis of Fe(C5H5)2 and CH3CN solution using argon as a carrier gas at the optimum temperature of approximately 900 degrees C. The effect of ferrocene concentration on the length and concentration of nitrogen in nanotubes was studied. Micro-structural features of the nanotubes were monitored employing scanning and transmission electron microscopic techniques. SEM studies reveal that with decreasing ferrocene concentration from 25 mg ml(-1) to 5 mg ml(-1), the length of the nanotubes vary from 80 microm to 430 microm. A feasible growth model has been described and discussed. X-ray photoelectron spectroscopic studies have confirmed the formation of nitrogen-doped carbon nanotubes. These studies reveal that the nitrogen concentration in the nanotubes decreases with the increase of ferrocene concentration. The present synthesis route also provides means of producing carbon nanotubes with different concentrations of nitrogen. 相似文献
95.
Gold nanoparticles of triangular morphology possess interesting optical properties with potential application in medicine and infrared absorbing coatings, however, little is known about conditions that favor their growth. In this paper, we have reinvestigated a time-tested recipe for the formation of gold nanospheres by citrate reduction of aqueous gold ions under boiling conditions (Turkevich recipe). Our principle findings are that gold nanotriangle formation is kinetically controlled and is highly favored at low temperatures. Furthermore, the presence of chloride ions from the precursor chloroaurate ions plays a major role in promoting the growth of <111> oriented triangular/truncated triangular particles. The presence of bromide and iodide ions that possess the ability to replace surface-bound chloride ions inhibits triangle formation to varying degrees. 相似文献
96.
Senapati S Ahmad A Khan MI Sastry M Kumar R 《Small (Weinheim an der Bergstrasse, Germany)》2005,1(5):517-520
97.
Recent studies have demonstrated that long-chain n−3 PUFA (LCn-3PUFA) are beneficial in reducing the risk of cardiac arrhythmias.
This study was conducted to determine the extent of incorporation of LCn-3PUFA into human atrium following supplementation
with a fish oil concentrate high in LCn-3PUFA. Volunteers preparing for coronary bypass surgery were randomized either to
the treatment group (n=8), receiving 6 g/d of fish oil concentrate (4.4 g of LCn-3PUFA), or the placebo group (n=9), receiving 6 g/d of olive oil for a minimum period of 6 wk. Blood samples were collected prior to commencement of treatment,
and preoperatively before bypass surgery. Atrial biopsies were obtained during surgery. The plasma and atrium samples were
analyzed by GC following trans-methylation to determine FA profile. Post-supplementation, the treatment group had significantly
higher plasma levels of 20∶5n−3, 22∶5n−3, and 22∶6n−3 than the placebo group. Analysis of the atrium total lipids revealed
a significant increase in the proportion of 20∶5n−3 following fish oil supplementation. There was no significant difference
in the concentration of 22∶5n−3 and 22∶6n−3 in the atrium total lipids; however, an upward trend was observed in subjects
receiving fish oil supplementation. In the phospholipid fraction of the atrium, both 20∶5n−3 and 22∶6n−3 increased, whereas
20∶4n−6 levels decreased. This study demonstrates for the first time that short-term supplementation with fish oil concentrate
results in significant incorporation of LNc-3PUFA with a concomitant depletion of the eicosanoid substrate (20∶4n−6) in the
human atrium. 相似文献
98.
An enhanced hybrid scheme of wavelength reservation for dynamic wavelength routed optical networks is proposed. The performance of a newly introduced composite-two-phase reservation protocol (C2P-RP) is evaluated and compared with the existing hybrid reservation protocol. By offering connection requests an enhanced scope of finding an end-to-end available wavelength, the C2P-RP scheme shows improved connection-request blocking performance. 相似文献
99.
100.
Guillermo Talavera Murali Jayapala Jordi Carrabina Francky Catthoor 《Journal of Signal Processing Systems》2008,53(3):271-284
Nowadays embedded systems are growing at an impressive rate and provide more and more sophisticated applications characterized
by having a complex array index manipulation and a large number of data accesses. Those applications require high performance
specific computation that general purpose processors can not deliver at a reasonable energy consumption. Very long instruction
word architectures seem a good solution providing enough computational performance at low power with the required programmability
to speed up the time to market. Those architectures rely on compiler effort to exploit the available instruction and data
parallelism to keep the data path busy all the time. With the density of transistors doubling each 18 months, more and more
sophisticated architectures with a high number of computational resources running in parallel are emerging. With this increasing
parallel computation, the access to data is becoming the main bottleneck that limits the available parallelism. To alleviate
this problem, in current embedded architectures, a special unit works in parallel with the main computing elements to ensure
efficient feed and storage of the data: the address generator unit, which comes in many flavors. Future architectures will
have to deal with enormous memory bandwidth in distributed memories and the development of address generators units will be
crucial for effective next generation of embedded processors where global trade-offs between reaction-time, bandwidth, energy
and area must be achieved. This paper provides a survey of methods and techniques that optimize the address generation process
for embedded systems, explaining current research trends and needs for future.
相似文献
Francky CatthoorEmail: |