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In this paper the performance of different free stream boundary conditions has been investigated. By performing two dimensional free jet calculations, a test case for which an analytical solution is available, it has been shown that boundary conditions in which the pressure is prescribed perform significantly better than boundary conditions in which the velocity is prescribed. Furthermore, it has been shown that pressure boundary conditions allow for much smaller computational domains than velocity (free-slip) boundary conditions.  相似文献   
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1IntroductionShadowmoireinterferometryisawholefieldnoncontact3Dmeasurementtechnique.ItisfirstappliedbyH.Takasaki[1]in1970.In...  相似文献   
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We have addressed the question whether the level of UV-B induced DNA damage can be accurately assessed by the measurement of the rate of unscheduled DNA synthesis (UDS). Cultured human fibroblasts were irradiated with UV radiation at 290, 313 or 365 nm. The LD50 was 85 J/m2 at 290 nm, 4500 J/m2 at 313 nm, and 70 kJ/m2 at 365 nm. The analysis of UDS measurements indicate complete arrest of repair processes within 24 h after irradiation, irrespective of the dose (in the range 10-60 J/m2 at 290 nm, and 250-1000 J/m2 at 313 nm). Irradiation at 365 nm failed to yield detectable evidence of UDS. Incubation of irradiated cells with an antiserum directed against both 6-4 type and cyclobutane-type pyrimidine dimers shows a clear parallelism between the disappearance of the antibody-binding determinants and the variation of the rate of UDS vs time after the end of the irradiation. Thus it is concluded that in UV-B irradiated normal cultured human fibroblasts, the lack of UDS reflects the absence of immunodetectable pyrimidine dimers.  相似文献   
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The ibuprofen--cyclodextrin inclusion complex was prepared by theco-precipitation method. The identity of the obtained product was verified by X-ray and thermogravimetric techniques. The effect of -cyclodextrin on the stability of ibuprofen was analysed.  相似文献   
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Performance limits of NRZ data transmission at 10 Gbit/s over standard single mode fiber (SSMF, G.652) without the deployment of in-line erbium-doped fiber amplifiers (EDFAs) are evaluated by means of numerical simulation. The fiber system was modeled using the standard split-step Fourier algorithm for the solution of nonlinear Schroedinger equation. The effect of group velocity dispersion (GVD) compensation scheme, degree of GVD compensation of the SSMF, and input optical powers to SSMF and to the dispersion compensating fiber (DCF) have been investigated with the aim to maximize the distance between transmitter and receiver. We have found that a post-compensation scheme performs better than the pre-compensation scheme and that, by careful selection of input powers and degree of GVD compensation, it should be possible to keep the bit-error-ratio (BER) below 10 upper index = 15 for an SSMF length of 270 km.  相似文献   
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实验选取六枝(LZ)原煤及其在固定床热解所得半焦,采用常压程序升温还原 质谱法(AP-TPR-MS)与化学法相结合考察温度和气氛对固定床热解过程中硫变迁行为的影响。对于LZ煤而言,经氮气气氛500℃热解后,只能使煤中部分不稳定有机硫分解,黄铁矿硫却不能分解;而经氮气气氛700℃热解后可以使不稳定有机硫和黄铁矿硫全部分解。合成气气氛在500℃以前煤中的不稳定有机硫和黄铁矿硫就能全部分解,且随着温度的升高,合成气表现出与氢气相近的脱硫活性。1.0% O2-N2对于六枝煤并没有明显的脱硫效果,这与氮气气氛相差不大。  相似文献   
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JAN SLOVÁK 《Molecular physics》2013,111(12):1981-1987
A new series of computer simulations on a fluid of pseudo-hard bodies has been conducted in order to find a closed analytical expression for the direct correlation function as a function of the intermolecular distance and fluid density, in analogy with a similar expression for the fluid of hard spheres. A pseudo-hard body resulting from the extended primitive model of water has been considered. The accuracy of the expression has been tested against computer simulation results for pair correlation function and pressure of the system and turned out to be fairly high. The direct correlation function is important for the construction of weighted density functionals, and consequently any other theoretical study of the properties of inhomogeneous systems containing associating component.  相似文献   
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The heats of formation of haloacetylenes are evaluated using the recent W1 and W2 ab initio computational thermochemistry methods. These calculations involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh quality, extrapolations to the one-particle basis set limit, and contributions of inner-shell correlation, scalar relativistic effects. and (where relevant) first-order spin-orbit coupling. The heats of formation determined using W2 theory are: δH1 298(HCCH) = 54.48 kcal mol?1, δHf 298(HCCH) = 25.15 kcal mol, δHf 298(FCCF) = 1.38 kcal mol?1, δHf 298(HCCC1) = 54.83 kcal mol?1, δHf 298(CICCC1) = 56.21 kcal mol?1, and δHf 298(FCCC1) = 28.47 kcal mo1?1. Enthalpies of hydrogenation and destabilization energies relative to acetylene were obtained at the WI level of theory. So doing we find the following destabilization order for acetylenes: FCCF > ClCCF > HCCF > ClCCCl > HCCCI > HCCH. By a combination of WI theory and isodesmic reactions. we show that the generally accepted heat of formation of 1,2-dichloroethane should be revised to ?31.8 ± 0.6 kcal mol?1, in excellent agreement with a very recent critically evaluated review. The performance of compound thermochemistry schemes, such as G2, G3, G3X and CBS-QB3 theories, has been analysed.  相似文献   
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