构造图形巧解向量问题

平面向量由于具有代数形式和几何形式两种特征,使其成为中学数学知识网络的一个交汇点,也成为高考命题的一个热点.纵观近几年的高考试题,不难发现,平面向量已从一种工具逐渐变为高考考查重点.作为考点,高考中此类问题多为选择题或填空题.笔者在对这类问题的解题教学中发现,不少平面向量问题均可利用其几何意义,构造几何图形,利用图形的形象直观和几何性质,使问题得到解决.     

巧用向量解竞赛题

高中数学教科书(试验修订本)新增加了平面向量内容,向量具有几何与代数的双重身份,使它成为中学数学知识的一个交汇点,成为联系多项内容的媒介.     

平面向量及其应用

<正>向量及其运算是高中教材的新增内容。作为现代数学重要标志之一的向量引入中学数学后,给中学数学带来无限生机。由于向量融数、形于一体,具有几何形式与代数形式的"双重身份",使它成为中学数学知识的一个交汇点,成为联系多项内容的媒介。因此向量的引入,大大拓宽了解题的思路与方法,使它在研究其它问题时获得了广泛的应用。     

高观点下的初等数学不等式

用高等数学中的著名不等式、向量、拉哥朗日中值定理等知识解决了中学数学中的一些不等式的证明,指出了中学数学中某些难以处理的问题的高等数学背景,用具体的材料说明了高等数学对初等数学的指导意义,进一步将高等数学的一些思想和方法渗透到中学数学中.     

初等几何的向量方法

在国外中学数学现代化运动中,如何改革中学几何是公认的关键和难点,已经提出了许多改革方案进行研究和试验。其中,从改革方法的角度有人主张以向量为工具来讲述欧几里得几何,比较引人注目。用向量方法研究初等几何问题,其基本作法和特点是什么?优越性在哪里?存在些什么问题,都是值得深入探讨的。本文对这些问题谈些粗浅的认识。 为省篇幅,向量的概念、基本运算和运算律作为已知,不再介绍;针对中学数学特点,文中也回避了向量线性相关和无关等较难理解的概念。     

高中数学向量的考查要求及教学建议

向量的几何形式和代数形式使它成为中学数学知识的一个交汇点,成为联系多项初等数学知识的桥梁。尤其是利用向量将一些几何元素间的位置关系转化为数量关系,将一些形式逻辑证明转化为数值计算,从而化难为易,化复杂为简单。向量作为新课程的重点内容之一,已经成为新课程卷高考命题的一个重点和热点,纵观新课程实施以来的命题实践,高考逐年加大了对向量部分的考查力度。     

向量基本定理的几何表示

 以纯向量为工具研究几何问题,将向量基本定理用几何形式表示,可以将几何中的基本元素点、线、面、体用一个公式表示,实现了几何问题与向量问题相互转化,从理论上给出了几何问题和代数问题相互转化的又一方法.这一方法不仅涵盖了笛卡儿的坐标法,而且从非正交的角度推广了笛卡儿的坐标法,并由此引出了许多新的结论、方法和题型,并从几何的角度推广了向量基本定理,给出了其确切的几何解释,形成了相应的向量几何理论.从实体几何的角度看,它解决了几何应用过程中的许多计算、证明和作图问题,并且丰富了欧几里得空间的内涵.     

关于二次曲线的中点弦问题

运用高等几何、数学分析、高等代数等高等数学知识，全段系统地分析了关于二次曲线的中点弦问题。在“整体、融合”的观点指导下解决了这个在中学数学教学中没有得到完全解决的问题。     

复数在平面几何中的部分应用

复数运算及其几何意义沟通了中学数学中代数、几何、三角各部分知识之间的联系,是三部分知识结合的一个很好题材。若能在教学中引导学生利用复数的四则运算及其几何意义来解决一些三角及几何问题,对培养学生的运算能力、逻辑思维能力和空间想象能力、开发学生智力、提高分析问题和解决问题的能力是很有益处的。     

向量在几何证明中的运用技巧

向量法是几何证明的有效方法,也是解析几何的基本问题之一,正确应用向量代数知识并结合一定的数学思想方法是向量在几何证明中的运用技巧.     

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.     

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.     

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.     

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.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.