排序方式: 共有83条查询结果,搜索用时 390 毫秒
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对鸡血藤中铁、锰、铜、锌、钙、镁和锶7种金属元素的化学形态进行分析;分别用0.45μm微孔滤膜、LSA-10大孔吸附树脂、正辛醇-水萃取体系,将鸡血藤中各元素分离为可溶态与悬浮态、有机态与无机态、醇溶态与水溶态,用电感耦合等离子体-原子发射光谱法(ICP-AES)测定7种元素的各形态含量。结果表明:鸡血藤中7种元素在原药中的含量高低依次为:钙、镁、铁、锰、锶、铜和锌,水煎液中锌和镁的提取率大于50%,其次是铜为45.2%;铜的颗粒吸附率最高为26.3%;镁的KOW参数在肠、胃液酸度下均大于1,铁和锰的KOW参数均小于1,元素的KOW值受pH影响。 相似文献
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This paper presents a numerical approach for modeling the interaction between multiple cracks in a rectangular plate under cyclic loads. It involves the formulation of fatigue growth of multiple crack tips under ruixed-mode loading and an extension of a hybrid displacement discontinuity method (a boundary element method) to fatigue crack growth analyses. Because of an intrinsic feature of the boundary element method, a general growth problem of multiple cracks can be solved in a single-region formulation. In the numerical simulation, remeshing of existing boundaries is not necessary for each increment of crack extension. Crack extension is conveniently modeled by adding new boundary elements on the incremental crack extension to the previous crack boundaries. As an example, the numerical approach is used to analyze the fatigue growth of three parallel cracks in a rectangular plate. The numerical results illustrate the validation of the numerical approach and can reveal the effect of the geometry of the cracked plate on the fatigue growth. 相似文献
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This paper presents a numerical approach of fatigue growth analysis of cracks emanating from a hole in infinite elastic plate
subjected to remote loads. It involves a generation of Bueckner’s principle and a hybrid displacement discontinuity method
(a boundary element method) proposed recently by the senior author of the paper. Because of an intrinsic feature of the boundary
element method, a general crack growth problem can be solved in a single region formulation. In the numerical simulation,
for each increment of crack extension, remeshing of existing boundaries is not necessary. Crack extension is modeled conveniently
by adding new boundary elements on the incremental crack extension to the previous crack boundaries. As an example, fatigue
growth process of an inclined crack in an infinite plate under uniaxial cycle load is modeled to illustrate the effectiveness
of the numerical approach. In addition, fatigue growth of cracks emanating from a circular hole in infinite elastic plate
subjected to remote loads is investigated by using the numerical approach. Many numerical results are given 相似文献
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部分中毒Pd/C催化剂上环戊二烯的加氢反应 总被引:3,自引:0,他引:3
用固定床反应器考察了Pd/C催化剂硫化前后环戊二烯的加氢性能,Pd/C催化剂经硫化后,生成环戊烯的得率由75%上升到97%。确定了最佳硫化条件。应用微型脉冲反应器和程序升温表面反应(TPSR)研究了硫化特性,发现硫在Pd/C催化剂在存在着两种吸附状态,吸附在对应于TPSR中低温峰位上的硫不影响加氢反应活性,吸附在对应于高温峰位上的硫引起催化剂催化活性下降。 相似文献
35.
半空间中一类次调和函数的增长性质 总被引:5,自引:5,他引:0
在Rn的半空间{x∈Rn,xn>0}中,得到了具有Dirichlet数据的Poisson积分在自然的积分收敛条件下满足增长性质u(x)=o(|x|),这里|x|→∞,这一性质对于半空间中满足一定条件的次调和函数仍然成立.该结果把复平面C中解析函数的增长性质推广到了n-维Euclidean半空间,并且推广了n-维Euclidean半空间中某些经典的结果. 相似文献
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研究了量子纠错码的等价性和保距同构,推广了Bogart等人的一些概念,并给出若干基本定理,这些定理对进一步研究量子码的等价性和保距同构是非常有用的.在此基础上构造出一个反例,证明了在量子情形下,MacWmiams的一个重要定理不成立. 相似文献
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不同质量浓度亚硒酸钠对豌豆芽苗菜生长及硒含量的影响 总被引:3,自引:0,他引:3
调查了不同质量浓度亚硒酸钠喷施对豌豆芽苗菜生长的影响及植物体硒富集情况。结果 表明,对苗长2.5cm、5.0cm的豌豆芽苗菜两次喷施,处理质量浓度高于150mg/L,豌豆苗芽长、芽干质量和鲜质量、根长、根鲜质量及产量均有大幅度下降。豌豆芽苗菜中大分子结合硒和全硒含量均随外源硒的质量浓度升高而增加,但明显低于全硒的增加趋势;150mg/L处理的硒吸收利用率出现明显下降。 相似文献