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1.
考虑了一类带权的有狄里克莱边界条件的椭圆方程:-div(|x|-2au)-λ/|x|2(a+1)u=|x|-bpup-1+μu-q,其中0∈ΩRN(N≥3),0≤a-2/2,a≤b,p=2N/N-2(1+a-b),0<λ<(N-2-2a/2)2,0<q<1. 并利用变分方法,在适当μ的情况下,证明方程至少存在两个正的弱解.  相似文献   

2.
目的 通过Meta分析评价高强度间歇训练(HIIT)对初中生身体成分的影响,为后续HIIT在改善身体成分方面提供理论依据。方法 利用Web of Science、PubMed、EBSCO、中国知网(CNKI)4个中英文数据库进行文献检索,收集有关初中生身体成分的随机对照试验(RST),参考Cochrane风险对研究文献进行风险质量评价,同时借助Review Manage 5.4 1和Stata 14.0 软件进行异质性检验、敏感性分析和发表偏倚分析。结果 共纳入16个RST。Meta分析结果显示:HIIT能显著减轻初中生体质量(MD = -1.18, 95%CI : -1.39~ -0.98, P <0.01);改善身体质量指数( BMI )(MD = -0.65, 95%CI : -0.79 ~ -0.51, P< 0.01);降低体脂率( MD = -0.46, 95%CI = -0.59~ -0.34 ,P < 0.01) 、腰围(MD = -1.08, 95%CI : -1.24 ~ -0.92 , P < 0.01)。在体质量方面,男生改善效果大于女生;在BMI和腰围方面,男女生改善效果差异不大;在体脂率方面,女生改善效果大于男生。结论 高强度间歇训练对初中生身体成分具有良好的改善效果,可明显降低初中生的体质量,改善初中生的BMI指数,降低初中生的腰围及体脂率。  相似文献   

3.
目的 了解吉安市中学生的营养状况及其影响因素,寻找相关膳食危险因素。方法 采用随机整群抽样的方法,对吉安市某中学在校800名中学生开展食物频率表膳食调查和一般情况调查,回收有效问卷信息进行分析。结果 体重指数(BMI, Body Mass Index)低于正常值的有130人(17.24%),高于正常值的有60人(7.96%),其中男生消瘦和超重检出率分别为12.47%、6.6%,女生检出率分别为4.77%、1.33%,多因素Logistics回归分析显示,超重、肥胖的发生与奶茶摄入频次有关(P < 0.05)。结论 吉安市中学生存在一定的营养状况问题,且与特定的饮食习惯有关。  相似文献   

4.
本文考虑了如下的一类平面四次复Lotka-Volterra系统的可线性化问题=x(1-a30x3-a21x2y-a12xy2-a03y3),=-y(5-b30x3-b21x2y-b12xy2-b03y3).该系统为四次齐次多项式扰动下的具有$1:-5$线性项的复Lotka-Volterra系统,给出了该系统可线性化的充分必要条件.  相似文献   

5.
合成了一种新的西佛碱配体N,N''双水杨醛缩二氨基乙醚,并采用x射线单晶衍射法测定了它的晶体结构。该晶体属正交晶系空间群Pbcn,a=5.667(2)Å,b=9.192(3)Å,c=31.829(11)Å,v=1658.2(7)Å3,分子式为C18H20N2O3,Mr=312.36,Z=4,DC=1.251g·cm-3,晶体结构测定和UV,IR谱均表明分子内形成氢键。在甲醇溶液中有一个荧光发射带,λmax=443nm。  相似文献   

6.
举反例说明:对于矩阵的2-范数,存在矩阵ABC,使得ACB不是矩阵方程AXB-C=0的最佳逼近解,其中AB分别是AB的Moore-Penrose逆.  相似文献   

7.
非贵金属新型催化剂催化松香歧化动力学研究   总被引:1,自引:0,他引:1  
 以醇盐水解法制备的Ni-Al/MnOx(Ⅱ)为催化剂催化松香歧化反应,研究了反应的动力学特征,得到其动力学方程为:lnw=kt+1.326 7,其中反应速度常数k与反应温度T间的关系为k=0.103 6 e-8.854/RT.  相似文献   

8.
目的 建立蛇伤胶囊中5种蒽醌类成分含量测定分析方法,提升蛇伤胶囊质量标准。方法 采用Diamonsil C18色谱柱(250 mm×4.6 mm,5 μm),流动相为甲醇(A)-0.1%磷酸水溶液(B),梯度洗脱(0~7 min,75% A;7~30 min,75% A→90% A;30~40 min,90% A),流速为1.0 mL·min-1,检测波长为254 nm,进样量10 μL。结果 5个待测组的线性范围:4.04~40.40μg/mL(r=0.9994)、4.16~41.60μg/mL(r=0.9991)、4.14~41.40 μg/mL(r=0.9959)、4.10~41.00 μg/mL(r=0.9993)和2.16~21.60μg/mL(r=0.9997)。平均回收率(n=6)分别为100.02%、100.02%、100.03%、99.99%和100.06%,RSD分别为0.40%、0.15%、0.30%、0.11%和0.47%。结论 所建立的方法操作简便准确且具有良好的重复性,可用于测定蛇伤胶囊中芦荟大黄素、大黄素、大黄酸、大黄酚和大黄素甲醚的含量。  相似文献   

9.
为探究煤体不同尺度孔裂隙特征及其对渗透率的影响,从我国14个大型煤炭基地分别取样,进行氮气吸附、压汞和CT实验,并将CT扫描后的煤样进行渗流实验。结果表明,各煤样中微孔和过渡孔多为封闭孔,连通性差,不利于渗流的进行。r=10 nm和r=100 μm的孔裂隙体积占比相对较大,贡献了煤体大部分孔隙率,S2和S3中的大尺度平行板孔隙为渗流提供了充足的空间。通过划分3种实验表征的优势孔径段,提出了综合表征孔隙率和分形维数的方法,得到各煤样的孔隙率范围为1.62%~11.60%,分形维数范围为2.29~2.78。煤样渗透率在0.000 2×10-15~ 0.652 5×10-15 m2之间,以中低渗为主。r<50 nm、50 nm≤ r ≤8.5 μm和r>8.5 μm的孔隙率分量与渗透率的关系分别为y=0.274 1x-0.078 1、y=0.067 4x+0.023 7和y=0.003 9x2.598 6,其中r>8.5 μm的孔隙率分量与渗透率的相关性最强。相对于氮气吸附和压汞实验,CT实验更适用于分析孔裂隙结构对水渗的影响。  相似文献   

10.
一类非线性中立型微分方程的振动定理   总被引:1,自引:5,他引:1  
 一类非线性混合中立型泛函微分方程(dn/dtn)(x(tax(t-τ)bx(t +τ))(q(t)f(x(t-ρ))+p(t)g(x(t+σ)))=0,被讨论,得到了各种解的振动性的充分条件.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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