丰富安卓手机Home功能

有很多安卓手机只有四个功能按键,在Home键、设置、返回、搜索这四个按键中,长按搜索键可以自定义搜索方式,设置、返回键没啥搞头,但长按Home键也只能打开最近使用的应用程序,相对于安卓系统中花样繁多的任务管理应用,这个功能实在太逊了。那么有没     

量子化学软件的应用研究

量化软件的引入对学生学习、理解、应用《结构化学》起到积极作用，激发了学生的学习动机，便于教师调整教学内容和进度，优化教学过程。通过变分法在Gaussian软件包中的体现、Gaussian软件计算O2＋，O2，和O2-的键长，对比键级的结果以及α-π反馈键三个具体实例说明量子化学软件在《结构化学》教学中的应用，以及应用中的注意原则。     

《FIFA2004》按键全接触

进攻:a键:长传(有力量条控制)s键:短传(传给身边的队友,无力量条控制)d键:射门(按键越长,威力越打)q键:队员自动跑位w键:短传(有力量条控制,按键越长,威力越大)头球(点击此键,将有机会看见头球传球)z键:04中新增加的键(定位键)(可以选择三个不同的队员进行,多选择传球,不在是单一的了!)shift键:晃人键:跑动中,按一下shift键,做晃人动作(由于是试玩版,小弟用到现在只用出一种晃人动作)如有人,玩去其他的晃人动作,请你告诉大家一声!c键:原地停留中,按住c键再按方向键,可以看见球员,慢步趟球移动!c键+z键:不论再进攻还是防守中,先按住c键再按z…     

3个[AlB5O7（OH）6]2-簇的电子结构和红外光谱的DFT研究

采用密度泛函(DFT)方法,在B3LYP/6-311g*基组下,对3个[AlB5O7(OH)6]2-簇(I, II, III)的电子结构、稳定性和红外光谱进行了理论研究。结果显示3个簇中优化的键长和键角值与wiberg键级有关。[AlB5O7(OH)6]2-(I)的带宽最大,能量最低,稳定性最高。红外光谱研究显示BO3、BO4和AlO4基团振动频率的大小为BO3>BO4>AlO4,且BO3基团的振动强度也最大。此外,研究也显示非端基B-O键的振动频率较端基B-O键的振动频率大。     

四氢萘微观结构的量子化学研究

为了研究氢化芳烃的微观结构,进一步认识和理解氢化芳烃在催化裂化过程中的反应特性。以四氢萘为模型化合物,利用基于密度泛函理论的量子化学从头计算方法,对四氢萘的几何结构和电子结构进行了系统研究,得到了四氢萘不同位置C-H键和C-C键的键长、键级、键能以及电子云密度、前线轨道分布等微观结构信息。发现四氢萘结构具有轴对称特性,苯环上的C-C键和C-H键要远比环烷环的C-C键和C-H键稳定。由于受苯环的影响,会使得其环烷环上不同位置的C-C键的键长、键级和键能均具有明显差异,也导致环烷环上不同位置C-H键的键长、键级和键能有较明显的差异,具体表现为:对C-C键而言,与苯环相连的C-C键的键长较短,键级较高,键能也明显较高,而苯环β位C-C键的键能则明显较低;对C-H键而言,与苯环β位环烷碳原子上的C-H键相比,苯环α位环烷碳原子上的C-H键的键能明显较低。电子云分布计算结果能够较好地给出的这些C-C键和C-H键结构特征差异的原因。前线轨道计算结果表明,在催化裂化过程中,苯环α位环烷碳原子上的C-H键和β位C-C键较易受到催化剂酸性中心的进攻,是酸催化反应的位点。这些计算结果对于认识与理解氢化芳烃的反应特性具有一定的基础性理论意义。     

基于弧长密度的自动邻域半径鉴别FPFH提取算法

在快速点特征直方图(FPFH)的特征计算过程中,需要人工多次选择邻域半径,计算过程复杂且效率较低。针对该问题,提出基于弧长密度的自动邻域半径鉴别FPFH特征提取算法。给出点云弧长密度的计算方法,依据弧长密度估算多对点云的邻域半径,以提取FPFH特征并完成采样一致性初始配准,确定配准性能最优的半径与弧长密度值。在此基础上,使用最小二乘法拟合邻域半径与弧长密度之间的函数表达式,并与FPFH特征提取算法结合得到自动邻域半径鉴别FPFH特征提取算法。实验结果表明,该算法可根据点云弧长密度自动鉴别出合适的邻域半径,运算速度较快。     

微机系统内存的合理使用与常见问题解答

开机后内存检测时间长怎么办 通过设置Quick Power On Self Test和Esc键来解决。操作如下: (1)开机时,按Del键进入Setup; (2)选择BIOS Features Setup,回车; (3)使用PgDn键把“Quick Power On Self Test”设置为“Enabled”; (4)使用F10键退出(回答“Y”);开机自检内存时,按Esc键跳过自检。 随着内存价格急剧下降,电脑基本配置内存容量的增加,开机内存自检的时间越来越长,即使使用快速检测,把三遍检测改成一遍检测,时间也不短,因此需要使用Esc键直     

5-氟尿嘧啶…NO分子复合物的结构与性质

用密度泛函理论,在BL3YP/6-311++G**基组水平上研究5-氟尿嘧啶…NO复合物体系,用更大基组(6-311+G(2df,p)和aug-cc-pVDZ)进行单点能的计算,发现5个能量极小的复合物。同时,使用自然键轨道(NBO)法和分子中的原子(AIM)法对5-氟尿嘧啶和NO分子间的作用本质进行了分析。结果显示,5-氟尿嘧啶和NO的结合方式是NO的N、O原子与5-氟尿嘧啶的N-H键形成氢键,或O原子与5-氟尿嘧啶分子间通过弱π键结合在一起。最稳定复合物的结合能为-7.86 kJ/mol。N原子与5-氟尿嘧啶的结合更有优势,N结合的复合物中,NO键长缩短,伸缩振动频率蓝移,而O结合的复合物中,NO键长伸长,伸缩振动频率发生红移。     

量子化学方法研究阴离子表面活性剂在气液界面上的吸附

用量子化学方法中的密度泛函理论,在B3LYP/6-3IG水平上,对十二烷基硫酸钠（SDS）阴离子表面活性剂与水分子形成的水合物CH₃（CH₂）₁₁OSO₃ˉ（H₂O）_n（n=0～7）进行结构优化和频率计算。从分子水平上研究了CH₃（CH₂）₁₁OSO₃ˉ在气液界面上与水分子的相互作用。计算结果表明:（1）7个水分子与极性头均采用1:1型和2:1型,即极性头中一个氧原子或2个氧原子与水分子以氢键形式构成水合层;（2）CH₃（CH₂）₁₁OSO₃中的氧原子与水分子中的氧原子最短氢键的键长（O-O键长）在0.27～0.31 nm之间,H…O键长在0.19～0.21 nm之间,O-H…O键角在140°～167°之间,均属于中强氢键:（3）水合物R（S-O）平均键长比表面活性剂单体分子分别增长了,说明形成水合物后S-O间的键减弱;（4）结合能D₀从64.04 kJ/mol增加到.428.29 kJ/mol,说明随着水分子数的增加,所获得的7种水合物的稳定性依次增强,表明最终形成的水合层是稳定的:（5）随着水分子数增加疏水基链长收缩,亲水基总电荷增加,C12-O13-S14的键角增大;（6）由于烷烃链带有了弱电荷,使胶束内核带有了部分极性,此种极性介于烷烃油相和水相的极性之间,利于表面活性剂在溶液中的聚集。     

六水氯化镁分子与电子结构的理论化学研究

利用量子化学从头算方法,采用RHF/6-31G*和RHF/6-311G*方法,分别研究了六水氯化镁的分子结构与电子结构。计算结果表明,不同的计算方法,所得的结论基本一致,在六水氯化镁模型分子中,两个水分子与氯化镁结合松弛,以RHF/6-311G*计算为例,R[O-Mg]键长分别为0.3972nm和0.3839nm,这两个水分子游离在氯化镁的最外层,结合呈松散状态,极易脱除;另两个水分子与氯化镁结合适中,R[O-Mg]键长分别为0.2142nm和0.2152nm,最后两个水分子与氯化镁结合较牢,R[O-Mg]键长均为0.2081nm,这两个水分子最难脱除。本研究从理论化学的角度合理地解释了六水氯化镁脱水过程的实质,并由此深化对六水氯化镁的内部结构的认识,这种量子化学的计算方法是对现有的六水氯化镁实验研究方法的有益补充。     

BP神经网络计算法及共价键长计算的研究

提出了ＢＰ神经网络权值、阈值调整的双动量算法和学习率调整的批处理半恢复自适应调整法，基于此法计算了１５种含氢原子共价键的键长，计算键长的平均相对误差为０．１１％，结果表是，此二法的结合使用改善网络的总体收敛性。     

超导材料分子设计探讨

通过分析电流、电阻产生的原因和机理,提出只有处于特殊结构中的电子对才可能成为超导体。根据量子化学计算结果推测,氮杂十八轮烯衍生物的金属复合物可能会成为超导结构基元。     

Molecular geometry and substituent generation: A mathcad program

A MathCAD program, SUBSGEN, is presented. This program uses the standard mathematical vector and matrix notation of MathCAD to perform the following functions: (i) read in crystal lattice constants and atom positions in fractional coordinates; (ii) convert to orthonormal Cartesian coordinates; (iii) generate substituents in arbitrary positions; (iv) generate substituents in symmetry-defined positions; and (v) calculate internal geometry: bond lengths, bond angles and torsion angles.     

Ab initio calculations on the five-membered alumino-silicate framework rings model: implications for dissolution in alkaline solutions

An ab initio restricted Hartree-Fock calculation utilising the standard 6-31G basis set was used to calculate total energies after PM3 calculations of energy-optimised geometries for the five-membered alumino-silicate framework rings cluster for a total of ten T sites. Calculations have shown that in the absence of protons or other ions, the most favourable sites for 1A1, 2A1 and 3A1 substitution of Si are the T6, T1 and T9 sites respectively. With more Al atoms replacing Si in a cluster, T-O bond lengths and T-O-T angles show lengthening and sharpening trends respectively, which indicates that the structure is distorted to a more relaxed symmetry with Obr atoms moving outwards. The calculated bond lengths and angles have been shown to match the values observed in previous studies, including those for a four-membered alumino-silicate single ring cluster. Based on the optimised five-membered alumino-silicate framework rings model, a further ab initio HF calculation has been conducted on ring breakage for releasing Al(Q3) and Si(Q3) centres to form T(OH)4 and HOT(OM)3 tetrahedra under local and highly alkaline environment. The obtained results suggest that Al(Q3) compared with Si(Q3) breaks more readily with the exothermal reaction enthalpy being in excess of -244.4 kJ/mol, while the most reactive Si(Q3) centre shows an exothermal reaction enthalpy of only -33.8 kJ/mol. This indicates that Al dissolves in preference to Si in local environment. The dissolution mechanism of the five-membered Al-Si framework rings model in highly alkaline solutions has been suggested to be composed of an ion-pairing reaction and an interaction between the remaining broken ring cluster triple bond TOH and MOH.     

A comparison of calculated NMR shielding probes

In a strong magnetic field, covalently bonded hydrogen nuclei located over the plane of an anisotropic pi bond-containing functional group experience magnetic shielding (or deshielding) that results from the combined effect of the magnetic anisotropy of the functional group and other nearby covalent bonds plus other intramolecular shielding effects. These effects can now be calculated with reasonable accuracy using ab initio methods. We have investigated several computational probes of the magnetic shielding surface near anisotropic functional groups and compared the results to previous reports of experimental observations in example structures. GIAO-HF in Gaussian 03 was employed to calculate isotropic shielding values and to predict the net NMR shielding increment for several computational probes: methane, diatomic hydrogen, a hydrogen atom, a helium atom, or a ghost atom, each held in various positions over simple test molecules (ethene, ethyne, benzene and HCN) that contain the functional groups studied. Also, the effect of performing single point calculations versus constrained geometry-optimized calculations was examined. In addition, the effect of the angle of the orientation of the probe molecule (in the case of CH(4) and H(2)) relative to the pi bond in the test molecule was studied. Finally, the atomic charges in the molecular probes (CH(4) and H(2)) were computed to investigate the nature of the interaction of the probe with the test molecule. The optimal, most economical computational results were obtained using single point calculations of a diatomic hydrogen probe oriented perpendicular to the surface (or axis) of the test molecule.     

计算机自动结构解析专家系统研究─—一个新的子结构自动生成算法

为了结构的自动解析，本文定义了４１个结构片断，这些结构片断是带有键属性的。在此基础之上，利用组合数学，穷举生成一层子结构，以用于子结构／子光谱相关约束条件的生成。     

Investigation of base pairs containing oxidized guanine using ab initio method and ABEEMσπ polarizable force field

The integrity of the genetic information is constantly threatened by oxidizing agents. Oxidized guanines have all been linked to different types of cancers. Theoretical approaches supplement the assorted experimental techniques, and bring new sight and opportunities to investigate the underlying microscopic mechanics. Unfortunately, there is no specific force field to DNA system including oxidized guanines. Taking high level ab initio calculations as benchmark, we developed the ABEEMσπ fluctuating charge force field, which uses multiple fluctuating charges per atom. And it was applied to study the energies, structures and mutations of base pairs containing oxidized guanines. The geometries were obtained in reference to other studies or using B3LYP/6-31+G* level optimization, which is more rational and timesaving among 24 quantum mechanical methods selected and tested by this work. The energies were determined at MP2/aug-cc-pVDZ level with BSSE corrections. Results show that the constructed potential function can accurately simulate the change of H-bond and the buckled angle formed by two base planes induced by oxidized guanine, and it provides reliable information of hydrogen bonding, stacking interaction and the mutation processes. The performance of ABEEMσπ polarizable force field in predicting the bond lengths, bond angles, dipole moments etc. is generally better than those of the common force fields. And the accuracy of ABEEMσπ PFF is close to that of the MP2 method. This shows that ABEEMσπ model is a reliable choice for further research of dynamics behavior of DNA fragment including oxidized guanine.     

用密度泛函理论研究非诺贝特的构象和振动光谱

采用密度泛函B3LYP方法在6-31G*水平上对降血酯药物非诺贝特的构象和振动光谱进行了研究,得到了非诺贝特分子的平衡结构参数,并同文献中报道的非诺贝特晶体结构进行了比较,计算了目标分子在平衡构型下的振动基频和强度,计算结果表明,能量最低的构象其构型参数与实验值吻合最好,键长和键角分别只相差0.0123 A和1.52°,计算得到的红外图谱与实验结果相吻合,根据DFT计算的振动模式和IR光谱强度值对目标分子的实验振动基频进行了合理的指认和解释.     

氧分子在镍钛合金(100)表面吸附行为的研究

NiTi形状记忆合金作为一种广泛使用的生物医学材料，表面形成的氧化膜是其具有良好生物相容性的基础。氧分子在NiTi合金表面的吸附是其形成氧化膜的关键，应用离散变分Xα方法，首次对O2分子在B2结构NiTi(100)表面的吸附过程进行了理论研究，分别计算了在两种不同的O2分子吸附方式中Ti-O原子间的键级和电荷分布。结果表明：O2分子垂直接近NiTi(100)表面对其发生吸附更为有利。在吸附过程中，O2分子中只有一个氧原子被其最近邻的一个表面铁原子所吸附，而合金中其它表面原子及体相原子的电子结构没有变化。Mulliken集居数及局域态密度分析表明，吸附过程中铁原子与氧原子之间的相互作用主要是由2p(O)电子和4s，4p(Ti)电子贡献。