Spatial patterns of ephemeral plants in Gurbantünggüt Desert

In the present research,the authors measured parameters of richness,cover and importance value of ephemeral and ephemeroid plants on south-north and east-west transects in the Gurbantünggüt Desert in early spring,and investigated and analyzed the microhabitats,such as terrain,geomorphology,soil physical-chemical properties and crusts. By comparison,the regional differences in the ephemeral distribution in the desert were revealed. The species of ephemeral plants in the south and center are the richest and those in the west are the poorest in the desert. The cover of ephemeral plants in the mid-south is higher than that in the north,and that in the mid-east is higher than that in the west. The response of ephemeral plants to the spatial variation of the desert habitat forms the population-habitat gradient of ephemeral plants. The characteristics are:(1) In the habitat with higher terrain,coarser textured soil with poorer sorting and correspondingly higher organic matter and lower alkali-saline contents,Carex physoides and Eremopyrum orientale are the dominant ephemeral plants;(2) In the dry habitat with lower terrain,looser textured soil,some organic matter,alkali-saline soil,and developed crust,the ephemeral plants Alyssum linifolium and Erodium oxyrrhynchum are of characteristic of drought and alkali-saline tolerance;(3) In the habitat with lower terrain,some water and more alkali-saline soil,the ephemeral plants Neotorularia torulosa and Hypecoum parviflorum being of alkali-saline tolerance are mainly developed. However,most ephemerals are distributed in a habitat order of higher terrain,some organic,and less alkali-saline soil on the above-mentioned ephemeral population-habitat gradient. The spatial gradient of variation in desert microhabitats is small,and as a whole,the physio-logical character of mesophytism is represented by the desert ephemerals.     

关于丢番图方程x(x+1)＝Dy3

设p为素数 ,证明了丢番图方程x(x+ 1) =Dy3在D=p 1(mod 3)时仅有解 (p ,x ,y) =(2 ,1,1) ,(2 ,- 2 ,1) ,(17,5 831,12 6 ) ,(17,- 5 832 ,12 6 ) ;在D =2p ,p≡ 2 ,3,5 (mod 9)时仅有解 (x ,y ,p) =(2 ,1,3) ,(- 3,1,3) ;在D =4p ,p=5或p≡ 2 ,3(mod 9)时仅有解 (p ,x ,y) =(3 ,3,1) ,(3,- 4,1) ,(5 ,4,1) ,(5 ,- 5 ,1) ,(5 ,6 85 9,133) ,(5 ,- 6 86 0 ,133)。     

在数学课堂中培养学生的创新能力

培养学生的创新能力是中学教育的一项主要内容,本文结合数学课堂教学过程中的实践活动,从教师教学观、培养学生自我学习能力,鼓励学生质疑问难,引导学生大胆猜想,加强综合性学科的渗透,巧设课堂练习等五个方面讲述了在培养学生创新能力方面的一些实际做法,希望这些做法对其他同仁有所借鉴。     

Lü混沌系统的同步与反同步

针对参数相同,初值不同的两个Lü混沌系统,基于Lyapunov第二方法研究了它们的同步与反同步问题.数值仿真结果证明了所设计的非线性控制器的正确性和有效性.     

Grüneisen参数体积相关性的理论研究

根据常用势模型运用关于Grüneisen参数体积相关性的Slater公式、Dugdale-McDonald公式和Vasehenko-Zubarev公式,计算了NaCl在0-30GPa压强范围内的Grüneisen参数,通过计算结果与实验数据的比较与分析,提出了对Grüneisen参数经验值一种新的修正方法,修正后的数据在整个压强范围内与实验值吻合得较好.     

Bernstein算子和Grünwald算子的线性组合

以第一类n阶Chebyshev多项式的零点作为插值节点 ， 通过Bernstein算子和Grünwald算子的线性组合构造一个新算子G_n(f;x). 如果f(x)∈C^j_{［-1,1］(0≤j≤9), 则Gn(f;x)在区间 ［-1,1］上一致收敛于f(x)∈C^j［-1,1］(0≤j≤9), 并且其收敛 阶达到最佳, 饱和阶为1/n¹⁰.}     

居加猜想的一个等价命题

文章利用数论中的一些简单结果,建立了居加猜想的一个等价命题。     

恐龙灭绝新猜想『男女』比例失调

曾经主宰地球的恐龙家族是如何完全从地球上消失的？这一直是个未解之谜。最近，美国科学家在研究鳄鱼生育原理的过程中发现了恐龙灭绝的可能原因：“男女”比例失调，雄性恐龙的灭亡导致了恐龙大灭绝。     

课堂教学与学生的创新能力培养

创新教育是素质教育的核心,如何使创新教育具备实施的条件和可能,其前提条件是要立足课堂教学.在教学中以教科书为主,以猜想为辅助条件,并且要保证在教学中的学生主体地位,这样才可以进一步提高学生的学习兴趣,激活学生的思维,开阔学生的思路.