已知条件概率P(x=t|x+y=t)求P(x=t)和P(y=t)的问题

本文对取非负整数的具有正概率的独立随机变量 x和 y在已知条件概率 P( x=t|x y=t)的某些条件下 ,给出了 P( x=t)和 P( y=t)的解     

Single-Crystal Epitaxial Thin Films of the Isotropic Metallic Oxides Sr1-xCaxRuO3 (0 le x le 1)

Single-crystal epitaxial thin films of the isotropic metallic oxides Sr1-xCaxRuO(3) (0 相似文献   

B3N3H6与氟代甲烷形成的氢键和双氢键的理论研究

运用量子化学从头算方法研究了B3N3H6与氟代甲烷HxCF4-x(x=1～3)之间形成的双氢键B-H...H-C和传统氢键N-H...F. 结果表明, 双氢键作用使BH键长增大与伸缩振动频率红移, 以及使CH键长减短与频率蓝移; 而传统氢键的作用使NH键长增大与频率红移. 电子密度拓扑性质分析表明这些相互作用具有氢键的基本特征. 自然键轨道分析表明分子内与分子间超共轭和重杂化理论可以解释这些氢键的形成机制.     

Long-range incommensurate charge fluctuations in (Y,Nd)Ba2Cu3O(6+x)

The concept that superconductivity competes with other orders in cuprate superconductors has become increasingly apparent, but obtaining direct evidence with bulk-sensitive probes is challenging. We have used resonant soft x-ray scattering to identify two-dimensional charge fluctuations with an incommensurate periodicity of ~3.2 lattice units in the copper-oxide planes of the superconductors (Y,Nd)Ba(2)Cu(3)O(6+)(x), with hole concentrations of 0.09 to 0.13 per planar Cu ion. The intensity and correlation length of the fluctuation signal increase strongly upon cooling down to the superconducting transition temperature (T(c)); further cooling below T(c) abruptly reverses the divergence of the charge correlations. In combination with earlier observations of a large gap in the spin excitation spectrum, these data indicate an incipient charge density wave instability that competes with superconductivity.     

Atomic Force Microscope Studies of Fullerene Films: Highly Stable C60 fcc (311) Free Surfaces

Atomic force microscopy and x-ray diffractometry were used to study 1500 A-thick films of pure C(60) grown by sublimation in ultrahigh vacuum onto a CaF(2) (111) substrate. Topographs of the films did not reveal the expected close-packed structures, but they showed instead large regions that correspond to a face-centered cubic (311) surface and distortions of this surface. The open (311) structure may have a relatively low free energy because the low packing density contributes to a high entropy of the exposed surface.     

钠过量0.94(K0.5Na0.5)NbO3-0.06LiNbO3 无铅压电陶瓷显微结构和电学性能的研究

采用固相合成法制备了0.94(K_(0.5)Na_(0.5+x))NbO_3-0.06LiNbO_3无铅压电陶瓷,并对钠过量对陶瓷的晶体结构、显微形貌、电学性能的影响进行了研究.XRD测试结果显示,所研究的所有陶瓷样品均为单一钙钛矿结构,而且在室温下均为正交相和四方相两相共存.当x=0.01时,陶瓷具有最优的压电性能,其压电常数d33、相对介电常数εr、平面机电耦合系数Kp和厚度机电耦合系数Kt分别为255pC/N,850,0.46和0.42.研究结果可以为KNN基压电陶瓷的结构和性能调控提供有益的参考.     

A late-transition metal oxo complex: K7Na9[O=PtIV(H2O)L2], L = [PW9O34]9-

Terminal mono-oxo complexes of the late transition metal elements have long been considered too unstable to synthesize because of repulsion between the oxygen electrons and the mostly filled metal d orbitals. A platinum(IV)-oxo compound flanked by two polytungstate ligands, K7Na9[O=Pt(H2O)L2], L = [PW9O34(9-)], has now been prepared and isolated at room temperature as air-stable brown crystals. X-ray and neutron diffraction at 30 kelvin revealed a very short [1.720(18) angstrom] Pt-O bond and no evidence of a hydrogen atom at the terminal oxygen, ruling out a better precedented Pt-OH complex. Density functional theory and spectroscopic data account for the stability of the Pt(IV)-oxo unit by electron withdrawal into delocalized orbitals of the polytungstates.     

Crystal Structure of Kernite, Na2B4O6(OH)2 {middle dot} 3H2

Kernite, Na(2)B(4)O(6)(OH)(2). .3H(2)0, contains parallel infinite chains of the borate polyanion[B(4)O(6)(OH)(2)](n)(2n-). The chains are composed of six-membered rings containing one boron-oxygen triangle and two boron-oxygen tetrahedra. The rings are linked through commonly shared boron-oxygen tetrahedra.     

酯酶同工酶的醋酸萘酯 -铁氰化钾染色法的研究

酯酶可将α-醋酸萘酯和β-醋酸萘酯水解生成醋酸和萘酚,利用萘酚能与铁氰化钾反应生成有色物质萘醌的性质可对电泳凝胶上的酯酶同工酶进行染色.     

不定方程x(x+1)(x+2)(x+3)=33y(y+1)(y+2)(y+3)的整数解的研究

主要运用Pell方程、递推序列、同余式及(非)平方剩余等一些初等的证明方法,对不定方程x(x+1)(x+2)(x+3)=33y(y+1)(y+2)(y+3)的解进行了研究.证明了该不定方程仅有1组正整数解(x,y)=(9,3).同时给出了不定方程(x~2+3x+1)~2-33y~2=-32的全部整数解.     

珠三角土壤~（238）U·~（226）Ra·~（232）Th和~（40）K含量水平研究

[目的]为了调查土壤中天然放射性核素的水平和分布。[方法]利用高纯锗γ谱仪,调查珠三角区域内采集的796个土壤样品的天然放射性水平。[结果]土壤放射性核素238U、226Ra、232Th和40K的平均含量分别为142.4、135.9、196.9、670.2 Bq/kg。[结论]珠三角土壤中主要天然放射性核素含量高于全国背景含量,主要表现为土壤铀、钍含量较高。     

A Quantum State-Resolved Insertion Reaction: O((1)D) + H(2)(J = 0) --> OH((2) product operator product operator product operator, v, N) + H((2)S)

The O((1)D) + H(2) --> OH + H reaction, which proceeds mainly as an insertion reaction at a collisional energy of 1.3 kilocalories per mole, has been investigated with the high-resolution H atom Rydberg "tagging" time-of-flight technique and the quasiclassical trajectory (QCT) method. Quantum state-resolved differential cross sections were measured for this prototype reaction. Different rotationally-vibrationally excited OH products have markedly different angular distributions, whereas the total reaction products are roughly forward and backward symmetric. Theoretical results obtained from QCT calculations indicate that this reaction is dominated by the insertion mechanism, with a small contribution from the collinear abstraction mechanism through quantum tunneling.     

Thin Films of n-Si/Poly-(CH3)3Si-Cyclooctatetraene: Conducting-Polymer Solar Cells and Layered Structures

The optical and electronic properties of thin films of the solution-processible polymer poly-(CH(3))(3)Si-cyclooctatetraene are presented. This conjugated polymer is based on a polyacetylene backbone with (CH(3))(3)Si side groups. Thin transparent films have been cast onto n-doped silicon (n-Si) substrates and doped with iodine to form surfacebarrier solar cells. The devices produce photovoltages that are at the theoretical limit and that are much greater than can be obtained from n-Si contacts with conventional metals. Two methods for forming layered polymeric materials, one involving the spincoating of preformed polymers and the other comprising the sequential polymerization of different monomers, are also described. An organic polymer analog of a metal/insulator/metal capacitor has been constructed with the latter method.     

关于 Pell 方程组 x2-s2(s2-1 )y2 =1 与 y2-Dz2 =4的解

设D=p_1…p_j(1≤j≤3),p_1,…,p_j(1≤j≤3)是互异的奇素数.利用初等方法讨论了Pell方程组x~2-s~2(s~2-1)y~2=1(s∈Z+,s≥2)与y~2-Dz~2=4的解的情况.     

N-硝基苯基脲衍生物生物活性的研究

试验了N -硝基 -N - (2 ,4,6—三氯苯基 ) -N′- 2 -甲氧基苯基脲对双子叶作物油菜的植物生长调节活性及对双子叶杂草青葙的除草活性 ,试验结果表明 :该化合物对油菜基本不具有植物生长调节活性 ,对青葙则具有显著的除草活性     

小美旱杨插条苗(1-0)施肥的研究

通过田间试验,对小美旱杨1年生插条苗施用N,P,K矿质肥料的效果及其生长规律进行了研究。结果表明:华北地区的黄潮土所含N,P元素不能满足苗木生长的需要,而含K丰富。培育小美旱杨1年生插条苗需施用N和P肥,K肥可以不施。最佳施肥量为:N200kg/ha,P_2O_6100kg/ha;其N,P,K比例为2∶1∶0。根据当前的肥料和苗木的市价,用反应曲面方程计算获得最大经济效益的施肥量为N273.93kg/ha,P_2O_6121.15kg/ha。     

Whole-genome identiifcation and expression analysis of K+eflfux antiporter (KEA) and Na+/H+antiporter (NHX) families under abiotic stress in soybean

Sodium toxicity and potassium insufifcient are important factors affecting the growth and development of soybean in saline soil. As the capacity of plants to maintain a high cytosolic, K+/Na+ratio is t...     

毛鸡骨草氮、磷、钾营养特性及配方施肥效应研究

[研究目的]探讨毛鸡骨草的氮、磷、钾营养特性以及氮磷钾肥配施对其产量的影响。[方法]通过分析不同生长时期叶片氮、磷、钾含量变化情况研究毛鸡骨草营养特性;采用四因素三水平正交设计,研究了氮磷钾配施对毛鸡骨草产量的影响。[结果]毛鸡骨草叶片在6月初和9月初含氮量最高,8月中旬含磷量最高,5月中旬和7月中上旬含钾量最高;不同生长时期叶片中氮磷钾含量均为N〉K〉P;毛鸡骨草高产施肥配方为腐熟猪粪19500kg/hm^2,氮（N）180kg/hm^2以及钾（K2O）75kg/hm^2。[结论]氮肥宜于五月和八月施用,磷肥作基肥施用,钾肥于播种前和五月施用;在施用19500kg/hm^2腐熟猪粪的基础上,施用氮肥有极显著增产效应,磷、钾肥无显著增产效应。     

小麦中国春-Synthetic 6x 代换系穗花分化与耐旱基因的染色体定位

 【目的】通过对不同水分处理条件下小麦代换系的穗花发育进程和产量性状研究，确定控制小麦穗花发育的主效应染色体,并对耐旱基因进行染色体定位。【方法】以小麦CS-Synthetic 6x 整套染色体代换系及其亲本为材料进行干旱胁迫处理，对穗花分化过程进行观察，并对其产量性状分析研究。【结果】各代换系的穗花发育过程与亲本较为一致，都能正常通过穗原基和花原基分化两个阶段。在正常灌水条件下，2B代换系与父本Synthetic 6x 发育同步,分化最慢，7D次之，其它代换系发育较快，与母本中国春基本同步；在干旱胁迫条件下,2D代换系穗花分化较为缓慢,远远落后于中国春和其它代换系。且2D代换系每穗粒数、单穗粒重、千粒重等产量性状的抗旱系数均显著或极显著高于中国春。【结论】延缓穗花分化进程的主效基因可能位于2B和7D染色体上；耐旱相关基因可能位于2D染色体上。     

粉蓝烟草（Nicotiana glauca）花柱S-RNase的活性及其表达特异性研究

报道了粉蓝烟草自交不亲和性花柱S-基因产物的性质及时空表达特征。花柱S-基因产物是一种特异的糖蛋白（即S-糖蛋白）,具有极高的Rnase活性,因此又称S-Rnase。#+（32）P标记花粉RNA实验显示,授粉48h后,亲和性花粉管已生长进入子房,而自交不亲和性花粉管的rRNA含量急剧降低,并在花柱上半部特定区域停止生长。由此可推知,花柱S-Rnase通过与自交花粉管特异性识别进入管内分解rRNA,使花粉管蛋白质合成受阻,最终导致自交不亲和性反应。