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101.
CAI Guang-Yu LlU Zhong-Min SHI Ren-Min HE Chang-Qing YANG Li-Xin SUN Cheng-LinDalian Institute of Chemical Physics Acadernia Sinica Dalian Iiaorting 《天然气化学杂志》1995,(2)
A new route named as SDTO method for the synthesis of lightolefins from syngas has been proposed.That is to convert syngas todimethylether and then to convert dimethylether to light olefins.The catalystsfor the two conversion reactions have been developed.For the first reaction,the catulySt was synthesized by the combination of methanol synthesis catalystwith γ-Al_2O_3or zeolites which possesses both metallic and acidic functions.Thecatalyst for the second reaction was modified SAPO-34 molecular sieve.Thevariables of the reactions have also been investigated.The results from theserial connection of the two conversion steps without any separation show thatthe yield of C_2~-C_4~- olefins Could be>100g/(m~3 syngas). 相似文献
102.
103.
聚醚醚酮链结构与反应的模型化合物的量子化学研究 总被引:1,自引:1,他引:0
利用AM1方法对聚醚醚酮模型化合物全优化,结果为:芳环平均相互扭转角为33.0度,桥键角117.0-118.0度,其分子结构拓扑图形表明:所有苯环(核)为平面构型,但其内角扭曲;其氢原子对苯环构型无实质性贡献,在更长链的计算中,冻结苯核与氢原子也得出满意结果,根据Mulliken键序与电荷讨论了醚交换与磺化反应。 相似文献
104.
Gabor Schmera Adi Bulsara David Pierson Frank Moss Enrico Di Cera 《Journal of statistical physics》1993,71(5-6):1179-1190
We consider the class of experiments which can be characterized by a Fokker-PIanck dynamics corresponding to the overdamped motion of a state point in a suitable stochastic potential. We assume that the general form of the potential is known (or can be guessed with reasonable accuracy), but that its parameters are to be determined experimentally by measurements made with a noisy instrument. This possible method for determining the potential parameters, which exploits the system's own internal stochastic motion in order to explore rapidly its available parameter space, is substantially more efficient than traditional methods involving time averages of single point measurements, and yet does not appear to have been previously considered. The method could be important when, for example, the experiment must be completed in a limited time owing either to the expense of the experimental materials or to the temporary stationarity of the preparation, situations which are commonly encountered in experimental biochemistry and biology. 相似文献
105.
P. Di Martino P. Conflant M. Drache J. -P. Huvenne A. -M. Guyot-Hermann 《Journal of Thermal Analysis and Calorimetry》1997,48(3):447-458
The polymorphic forms II and III of paracetamol were obtained by melting the marketed form I. Under the melting and cooling conditions used, it was possible to obtain forms I, II and III. The recrystallization conditions and the physical properties of forms II and III were investigated by means of various techniques: thermomicroscopy, DSC analysis, infrared microspectrometry and X-ray powder diffraction at room temperature and as a function of temperature. Form III was found to be very unstable. However, its formation seems to be an important intermediate step in the preparation of form II. 相似文献
106.
陈迪 《应用数学与计算数学学报》1994,8(1):70-76
本文讨论了具有r个成败型元件串联系统可靠性的置信下限问题。研究了虚拟系统法置信下限的小样本性质,证明了,在通常情况下虚拟系统法置信下限要大于常见的L-M法置信下限.更一般地,本文证明了在成败型试验中,当成功数与试验数之比保持不变时,试验次数的增加将直接缩小成功率置信区间的长度。 相似文献
107.
在随机删失下研究了乘积限过程和累积失效率过程的振动模的局部性质 .给出了这两个过程的振动模的重对数律 ,并应用这些结果得到了几种核密度估计和Bahadur-Kiefer过程的精确收敛速度 相似文献
108.
Then-th commutator for a,b in a ringR is defined inductively as follows: [a,b]1=[a,b]=ab−ba and[a,b]
n=[[a,b]−1,b]. We characterize the ringsR without non-zero nil right ideals in which[a,b]
nis nilpotent or regular for alla,b∈R. We also examine the case whereR is a semiprime ring with involution in which[t
1, t2]nis nilpotent or regular for all tracest
1,t2∈R. 相似文献
109.
Summary The results of local meteorology, solar radiation and ground-level ozone measurements taken in Antarctica during the second
Italian expedition (December 86–February 87) at Terra Nova Bay are presented. During the summer months the site of the Italian
base camp is characterized by a thin strip of deglaciated ground, along which the temperature measurements close to the ground
and up to 6 m high show a strongly superdiabatic profile. This irregular trend of the temperature in the surface layer is
mainly due to the notable incoming amounts of radiation and to the extreme transparency of the atmosphere. This is also shown
by the low values of the ratio between total radiation and diffuse radiation. The ground is thus subjected to intense heating,
especially in the warmer hours of the day, while the surface layer of the atmosphere will be characterized by strong upward
heat fluxes and by turbulent convective movements. Vertical-temperature-profile measurements show an almost forced persistence
in the superdiabatic trend, which tends towards isothermic values only as a resultof rapid variations in the direction and
intensity of the wind, connected to the downward flux of cold air masses, shown also by the simultaneous increases in ground-level
ozone concentrations which would support the presence of dry-deposition processes in the lower layer. However, the complex
local orography and the horizontal discontinuity (sea, deglaciated coast, snow-covered surfaces) do not permit a correct application
of profile flux relations, normally used in studies on groundlevel dry-deposition.
Paper presented at the IV Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 22–24, 1987, Rome. 相似文献
110.
In this paper, optical limiting property in a magnetic fluid film is studied. The relationship between the emergent power and the incident power is investigated experimentally and theoretically. It is found that the limiting threshold is linear with the diaphragm aperture which accord with the theoretical prediction. The external magnetic field will affect the limiting property, and increase the limiting threshold. 相似文献