一类Mori纤维化的极面收缩态射

设X是n维非奇异射影簇,L是X上的丰富线丛,KX是X的典范丛,f:X→Y是极面收缩态射,其支撑除子为KX+(n-4)L.如果X与Y不是双有理等价的,那么(X,L)是一类特殊的代数簇.文中给出了(X,L)的结构的完整分类.     

射影流形上小收缩态射的翻转与法丛的关系

设X是射影流形,f:X→Y是X的小收缩态射,f的例外集E是光滑子簇.如果f(E)是零维的,E的维数不大于X的一半且法丛NE/X与 OE(-1)同构,t=codimE,那么f的翻转f :X X →Y一定存在.     

紧致黎曼流形上的Yamabe soliton

设(M,g)是n维黎曼流形,n≥3.考虑(M,g)上的Yamabe soliton:(R-ρ)g=1/2LXg,其中R是数量曲率,X∈X(M)是光滑向量场,是实常数.证明了:如果流形是紧致的,则数量曲率R是常数.     

关于高维代数族的Nef-值态射的结构

设M是有末端奇点的n维正规代数簇,L是M上的丰富线丛,(M,L)的数字有效值为τ=uv(u,v是互素的正整数),σ:M→W是由(M,L)决定的Nef-值态射.通过研究τ的取值情况对(M,L)进行分类,给出了当u=n-1时,(M,L)的较完整的分类,推广了一些文献的结果.     

Pontrjagin示性式的积分公式

令M是n维定向紧致C~∞流形,V是M上的m维实矢丛,P_k(V)是V的第k个Pontrjagin示性式。本文将计算积分 其中σ是M的任意闭(n-4k)-形式。 令VC是V的复化, 是复矢丛VC的光滑截面集,N是u_c的奇点集,并且N=Ni,其中Ni是N的连通分支。本文给出丛VC的光滑截面甜u_c=u+(-1)~(1/2)u′限制到Ni上的指标Iu_c(Ni)的定义,并且证明了下面的积分公式     

单位切丛T1S2n+1上的几何

本文给出一般矢丛上Sasaki度量的局部表示,特别得到单位切丛T1S^2n＋1上Sasaki度量的表达式.利用Grassmann流形上的示性类定义了T1S^2n＋1上的calibration,证明了L2n＋1是T1S^2n＋1上体积极小的子流形.采用切丛TS2n＋1上的不同联络,证明了Hopf向量场是S^2n＋1上体积最小的单位向量场.     

高阶边值问题周期解的存在性

用变分方法研究高阶边值问题(-1)n+1u(2n+2)+∑n/k=1 (-1)kcku(2k)-a(x)u +f(x,u)=0,0相似文献   

非紧流形上抛物方程的椭圆型梯度估计

给出完备非紧黎曼流形M上的抛物方程ut=△u+Xu+hu的正解的全局梯度估计,该估计与M的维数n无关.这里X是任意非零C 1向量场;h是定义在M×(0,+∞)上的非负函数,对于自变量x是C 1函数.作为应用,我们将给出该方程的解的Harnack估计.     

射影簇和向量丛的数字不变量对超二次曲面的刻画

设X是光滑的n维射影簇,E是X上的丰富向量丛,E的秩r＜n.如果E在X上的数字有效值为n/r,且X的皮卡数1,则X是超二次曲面Qn,E是线丛OQn(1)的直和.     

关于复流形上的有理曲线的存在性

如果存在n维复流形X到n维代数流形的非同构的全纯满射(n≥2),那么X中存在与复射影直线全纯同构的曲线.     

Markedness and its Interpretation in Language Use

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

Features of Women's language

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

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

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.