走出欧氏几何——论射影几何中理想元素、复元素和对偶元素作用

本文论述了射影几何中理想元素、复元素和对偶元素的引入对几何学从欧氏几何发展到射影几何的重要作用。

论复元素(α+βi,γ+δi)的KM表示法

本文经过分析论证,给出复元(α+βi,γ+δi)的KM表示法,据此就可将实平面拓广到复平面,在复平面上就可分别作出所有函数y=f(x)的完整的几何图象,并举例阐述其具体应用。

多元素复混肥在缺水杂交稻上的施用效果

多元素复混肥在适当缺水的杂交稻上施用 ,可增强水稻抗旱性 ,提高水稻分蘖、成穗及结实率 ,在干旱少雨情况下施用使水稻产量不减产或减产幅度低 。

多元素螯合复混肥对作物品质和产量的影响研究

采用氨基酸、黄腐酸生产中微量元素螯合物,按质量分数8%~10%将其添加在复合肥料中,制得成本较低的多元素螯合复混肥。以施用多元素螯合复混肥、专用肥、常规复合肥和不施肥等4种处理方式分别对小麦、玉米、黄瓜、甘蓝、苹果和梨进行田间试验。结果表明,施用多元素螯合复混肥不仅可以提高小麦、玉米、黄瓜、甘蓝、苹果和梨的产量,依次增产16.8%~19.1%、17.1%~21.6%、15.1%~18.4%、14.6%~17.8%、15.3%~20.4%和16.5%~19.9%,还能提高上述农产品中微量元素和可溶性固形物的含量,改善了农产品品质。

微量元素复合剂对嗜酸乳酸菌保存活力的影响

乳酸菌在人与动物的生活中分布及其广泛,在不断的深入研究后的今天,乳酸菌在工业、农牧业、食品和医药等产业中发挥着极大的作用。为了确保乳酸菌的培养能够在低成本中满足最高产量,需要研究延长乳酸菌活性的方法。方法:采取实验室的菌种,并制备5组含有不同含量的微量元素复合剂实验组进行培养后,每隔15~30 d进行活性检测观察,经过培养,然后进行细菌计数、镜下形态,最后将少量菌液离心分离使用牛津杯法进行抑菌检测。实验结果表明:适量浓度的微量元素复合剂对乳酸菌能起到增菌作用,其最适浓度为0.1 g/mL,相比对照组细菌的保存比例提高了0.8%。

高效多元素颗粒复混肥

随着化肥工业的迅速发展,复混肥巳成为当今肥料工业的重要发展方向之一。国外在复混肥的生产和应用方面起步较早,目前国外对含有多种营养元素的复混肥生产和应用已日趋普遍,复混肥在化肥工业中的比重逐年增长,50年代末,世界每年消耗化肥,按有效养份计,复混肥约占12％。进入80年代后,世界每年消耗化肥,按有效养份计。

复平面上的射影变换和二次曲线

较深入地揭示了共轭复元素在射影变换中和二次曲线上的一些性质 ,削弱了某些常用定义和定理所要求的条件 .

液-固相轧制法生产Al-8Sn-2.5Si-2Pb-0.8Cu-0.2Cr/钢复合轴瓦带的组织与性能

采用液-固相轧制复合法生产Al-8Sn-2.5Si-2Pb-0.8Cu-0.2Cr/钢复合轴瓦带,通过表面处理后的钢带能很好地与Al合金液润湿井产生冶金结合,且结合强度高、界面牢固,同时,液-固相轧制冷却速度大,金相观察表明Al合金为细晶的显微组织;电子探什观察表明;Si,Sn,Pb和Cr等元素在组织内分布均匀,有利于提高轴瓦性能。

First-principles study of stacking fault energies in Ni_3Al intermetallic alloys

The first-principles method based on the projector augmented wave method within the generalized gradient approximation was employed to calculate the superlattice intrinsic stacking fault（SISF） and complex stacking fault（CSF） energies of the binary Ni3Al alloys with different Al contents and the ternary Ni3Al intermetallic alloys with addition of alloying elements,such as Pd,Pt,Ti,Mo,Ta,W and Re.The results show that the energies of SISF and CSF increase significantly with increase of Al contents in Ni3Al.Addition of Pd and Pt occupying the Ni sublattices does not change the SISF and CSF energies of Ni3Al markedly in comparison with the Ni-23.75Al alloy.While addition of alloying elements,such as Ti,Mo,Ta,W and Re,occupying the Al sublattices dramatically increases the SISF and CSF energies of Ni3Al.The results suggest that the energies of SISF and CSF are dependent both on the Al contents and on the site occupancy of the ternary alloying element in Ni3Al intermetallic alloys.

实封闭域上的代数

在建立了实封闭域F上复元素域C与四元素体H后得到了:(1)全阵代数F2n中有子代数同构于C,全阵代数F4n中有子代数同构于H;(2)F上代数扩张体只有F、C和H;(3)设F是域K里上维数有限的真子域,则F是实封闭的K是代数闭域且K=F((-1)～(1/2));(4)设A是F上的有限维代数,①若A是可除代数,则A同构于F、C或H,②若A是中心可除代数,则A同构于F或H,③若A是单代数,则A同构于全阵代数Fn、Cn与Hn中之一,④若A是中心单代数,则A同构于全阵代数Fn或Hn,⑤若A没有非零幂零理想,则A=sum Mni from i=1 to l,其中Mni∈{Fni,Cni,Hni},i=1,2,…,l。

Effect of Land Cover Change on Soil Phosphorus Fractions in Southeastern Horqin Sandy Land, Northern China

In the past 50 years, large areas of the Horqin sandy land were afforested to prevent desertification. Although the afforestation policy appears successful, many people now doubt whether it is suitable to plant trees with high density on the poor soils in semiarid regions. Little is known about the impacts of afforestation on the sandy soil properties, although the evaluation of these impacts is fundamental to judge the rationality of afforestation policy. Soil phosphorus （P） fractions, acid phosphomonoesterase activities, and other soil chemical properties were compared among five adjoining typical ecosystems on poor sandy soils in southeastern Horqin sandy land. The ecosystems studied are natural elm savanna, degraded grassland, Mongolian pine （Pinus sylvestris var. mongolica） plantation, Chinese pine （Pinus tabulaeformis） plantation, and mixed plantation of Mongolian pine and poplar （Populus simonii）. The results showed that organic P dominated soil P （47%-65%） was the principal source of available P. The degradation of elm savanna to grassland significantly reduced soil pH and resulted in an overall reduction in soil fertility, although slightly increased labile inorganic P. Grassland afforestation had no significant influence on soil pH, organic carbon, and total N but significantly reduced total P. Impacts of grassland afforestation on soil P fractions depended on tree species. Natural elm savanna had higher soil P conserving ability than artificial plantations. Therefore, with the aim of developing a sustainable ecosystem, we suggested that vegetations with low nutrient demand （particularly P） and efficient nutrient cycling would be more suitable for ecosystem restoration in the semiarid region.

SPATIAL-TEMPORAL VARIATION OF HEAVY METAL ELEMENTS CONTENT IN COVERING SOIL OF RECLAMATION AREA IN FUSHUN COAL MINE

Grid method is employed for sampling covering soil at the test field,whic h is reclamation area filled by coal mining wastes for cropland in th e Fushun coal mine,Liaoning Province,the Northeast China.The soil samp les are taken at different locations,inclu ding three kinds of covering soil,th ree different depths of soil layers a nd four different covering ages of covering soil.The s patial-temporal variation of heavy metal element content in reclamatio n soil is stud-ied.The results indicate that the co ntent of heavy metal elements is decreasing year after year;the determin ant reason why the content of heavy metal elemen ts at 60cm depth layer is higher than t hat at 30cm depth layer and surface is fertiliz-er and manure application;the metal elements mainly come from external environment;there is no metal pollut ion coming from mother material(coal mining wastes)in plough layer of covering soil.

A numerical method for multiple cracks in an infinite elastic plate

This article examines the interaction of multiple cracks in an infinite plate by using a numerical method. The numerical method consists of the non-singular displacement discontinuity element presented by Crouch and Startled and the crack tip displacement discontinuity elements proposed by the author. In the numerical method implementation, the left or the right crack tip element is placed locally at the corresponding left or right crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. The numerical method is called a hybrid displacement discontinuity method. The following test examples of crack problems in an infinite plate under tension are included： “ center-inclined cracked plate”, “interaction of two collinear cracks with equal length”, “interaction of three collinear cracks with equal length”, “interaction of two parallel cracks with equal length”, and “interaction of one horizontal crack and one inclined crack”. The present numerical results show that the numerical method is simple yet very accurate for analyzing the interaction of multiple cracks in an infinite plate.

Al-matrix composite based on Al-Ca-Ni-La system additionally reinforced by L12 type nanoparticles

The structure of the quaternary Al?(2?4)wt.%Ca?Ni?La system near the aluminum corner has been studied using computational analysis in the Thermo-Calc program and experimental studies(electron microscopy,microprobe analysis and X-ray diffraction).Based on the phase equilibria data obtained,the experimental projection of the liquidus surface and solid state phase-field distribution of the Al?Ca?Ni?La system have been proposed.Microstructure studies reveal that the alloys with the 2?4 wt.%Ca,2?4 wt.%Ni and 1?3 wt.%La ranges have an ultra-fine hypoeutectic structure with 30%volume fraction of eutectic intermetallics,which allows one to classify these alloys as natural Al-matrix composites.The ultra-fine eutectic structure produces significant strengthening,the magnitude of which can be well described using the modified Orowan looping mechanism model.Small additives of Zr and Sc(0.2 and 0.1 wt.%,respectively)lead to significant strengthening(by^25%)due to the formation of L12 type phase(Al3(Zr,Sc))nanoparticles during annealing of the alloy at 350?400℃.Due to the high volume fraction of eutectic intermetallics,the new alloys have low coefficients of thermal expansion and high thermal stability of the structure and mechanical properties.

Potential Renaturalisation of Lakes as An Element Building Up Water Resources： An Example of Mosina Lake, Poland

Water deficits observed in many regions of the world make it necessary to implement measures intended to improve this situation. Poland is one of the countries with the poorest water resources in Europe due to its natural conditions and human impact. As a result of land reclamation carried out over decades, many elements of its hydrographic system have been changed, and some of them, like lakes, have disappeared altogether. In the days of the socio-economic transformation and more frequent extreme events, what seems worth considering is the renaturalisation of non-existing lakes, an idea presented in this paper on a selected example.

Enumeration Order Equivalence in Rational Numbers

The enumeration of elements of c.e. sets in the theory of computability and computational complexity has already been investigated. However, the order of this enumeration has received less attention. The enumeration orders of elements of c.e. sets by means of Turing machines on natural numbers are investigated. In this paper, we consider the enumeration orders of elements of c.e. sets on rational numbers. We present enumeration order reducibility and enumeration order equivalence on rational numbers and propose some lemmas and theorems on these concepts. Also, we show that the theories here hold for Rc and we could repeat the same theories in this domain, in a same way.