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981.
本实验讨论经高温高压水蒸汽处理后亚麻纤维的性能变化,优选亚麻纤维处理工艺,为亚麻纤维干纺提供了依据。 相似文献
982.
蔡天新 《山东大学学报(理学版)》1989,(2)
设P_r表至多有r个素因子(按重数计)的正整数.本文证明了: 设r≥4,k>0,l为整数,(l,k)=1,则当k≤x~(1-(4╱(r 1))-η,η>0时,在几乎所有的区间(y,y (k~3υ╱(φ(k))~2)log~(5 e)y)(y≤x)上至少存在c(ε)(k╱φ(k)) log~(4 ε)y个P_0≡l(modk)。 相似文献
983.
The composite membranes with cellulose acetate (CA) as the separating layer material and polyacrylonitrile (PAN) as the supporting
layer material were prepared for separating caprolactam (CPL) from CPL/water mixtures by pervaporation technique. The swelling
experiments were carried out to investigate the effects of swelling time and CPL concentration on the degree of swelling.
The results showed that the CA membrane reached swelling equilibrium within 24 h, and the degree of swelling first slightly
decreased then increased with the increase of CPL concentration in the feed under the experimental conditions. Respectively
comparing flux with permeance, and separation factor with selectivity, we found out that the separation performance of the
CA/PAN composite membrane is more strongly dependent on its hydrophilic/hydrophobic nature as well as on the effects of operating
parameters, such as feed composition concentration and feed temperature. 相似文献
984.
<正> This paper considers the problem of actuator failure compensation for a class of nonlinearsystems in the form of output-feedback.MT-filters are exploited to estimate the unmeasured states.The backsteppping technique is used to construct the controller recursively.The proposed compensationscheme can grantee the boundedness of all the closed-loop signals and asymptotic output tracking.Thetheoretical results are illustrated by a simulation example. 相似文献
985.
LI Li LU XiaoYu CAO ChongDe & DAI FuPing Department of Applied Physics Northwestern Polytechnical University Xi’an China 《科学通报(英文版)》2010,55(16):1674-1678
Solidification of Fe-7.5%Mo-16.5%Si ternary quasiperitectic alloy is investigated by using differential scanning calorimetry (DSC) and drop tube containerless processing techniques.The primary phase is identified as R (Fe5Mo3Si2) and the quasiperitectic phases are τ1 (Fe5MoSi4) and Fe3Si.With the decrease of droplet diameter, the cooling rate and undercooling of the droplets in-crease rapidly.The experiment result indicates that the solidification microstructure is composed of remnant primary phase, qua-sip... 相似文献
986.
<正> This paper discusses the null boundary controllability of two PDE's,modeling a compositesolid with different physical properties in each layer.Interface conditions are imposed. 相似文献
987.
Compared with traditional structure-based approaches for the identification of species-specific ligands, the ab initio approach, based on large-scale protein sequences from different species, has been used to locate specific sites that may be important to the molecular selectivity of species. Statistically significant differences in the distribution of residues in different species and differences in the physicochemical properties of residue-specific sites may largely account for species selectivity. The nicotinic acetylcholine receptor (nAChR), an important neuro-receptor with significantly different ligand selectivity in different species, was used to test our method. Because of the lack of nAChR structural information, the mechanism of ligand discrimination is unclear which hinders attempts at novel molecular design. In this study, the specific site residues 186 and 189 in the principal subunits and residues 34, 55, 56, 57, 106 and 112 in complementary subunits of nAChR were identified by applying our method with stringent statistical cutoffs. These sites were predicted to contribute to ligand selectivity and this result coincides well with the known experimental data. 相似文献
988.
介绍一种能保护好程序的硬加密和软加密相结合的方法,对安装软盘、硬盘主引导记录、系统软件及应用软件等进行处理,并结合关闭软驱和打印机的方法,控制软件的扩散。 相似文献
989.
Cai Manxin 《渤海大学学报(自然科学版)》1998,(3)
本文介绍一种通过电话网或分组交换利用调制解调设备在PC个人计算机上实现后台数据通讯及其管理系统。 相似文献
990.
蔡伟雄 《湖南科技大学学报(自然科学版)》1998,(2)
在旧城改造中,基础工程常遇到地下防空洞,防空洞荷载计算的准确与否直接关系到地基中防空洞的处理优劣.目前,有关资料及规程中所提供的计算方法均不够全面,为此,本文对防空洞的荷载计算方法系统地进行了推导和总结,给出了不同条件下防空洞的荷载计算公式,同时给出了计算实例.图3,表3,参3. 相似文献