946 resultados para IP masquerading


Relevância:

10.00% 10.00%

Publicador:

Resumo:

不同年龄植物材料的植株再生能力不同,繁殖质量也不同,要提高繁殖效率和再生苗木的质量,就要深入了解初始材料的生理生化状态,以便为具有优良遗传特性的适龄材料选择提供依据。文章检测了不同年龄黄波罗组培苗的脱落酸、生长素、赤霉素、玉米素型细胞分裂素型和异戊烯基型细胞分裂素含量并做了统计学差异分析,结果表明:随试材年龄增长,黄波罗微繁苗的iP-type CKs/总Cks降低,而Z-type CKs/iP-type CKs和GAs含量增加且有显著的统计学差异,可作为选择适龄微繁材料的生理指标之一。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The structural properties for various SiCO isomers in the singlet and triplet states have been investigated using CASSCF methods with a 6-311 +G* basis set and also using three DFT and MP2 with same basis set for those systems except for the linear singlet state. The detailed bonding character is discussed, and the state-state correlations and the isomerization mechanism are also determined. Results indicate that there are four different isomers for each spin state, and for all isomers, the triplet state is more stable than the corresponding singlet state. The most stable is the linear SiCO ((3)Sigma(-)) species and may be refer-red to the ground state. At the CASSCF-MP2(full)/6-311+G* level, the state-state energy separations of the other triplet states relative to the ground state are 43.2 (cyclic), 45.2 (linear SiOC), and 75.6 kcal/mol (linear CSiO), respectively, whereas the triplet-singlet state excitation energies for each configuration are 17.3 (linear SiCO), 2.2 (cyclic SiCO), 10.2 (linear SiOC), and 18.5 kcal/mol (linear CSiO), respectively. SiCo ((3)Sigma(-)) may be classified as silene (carbonylsilene), and its COdelta- moiety possesses CO- property. The dissociation energy of the ground state is 42.5 kcal/mol at the CASSCF-MP2(full)/6-311+G* level and falls within a range of 36.5-41.5 kcal/mol at DFT level, and of 23.7-28.9 kcal/mol at the wave function-correlated level, whereas the vertical IP is 188.8 kcal/mol at the CASSCF-MP2(full)/6-311+G* level and is very close to the first IP of Si atom. Three linear isomers (SiCO, SiOC, and CSiO) have similar structural bonding character. SiOC may be referred to the iso-carbonyl Si instead of the aether compound, whereas the CSiO isomer may be considered as the combination of C (the analogue of Si) with SiO (the analogue of CO). The bonding is weak for all linear species, and the corresponding potential energy surfaces are flat, and thus these linear molecules are facile. Another important isomer is of cyclic structure, it may be considered as the combination of CO with Si by the side pi bond. This structure has the smallest triplet state-singlet state excitation energy (similar to2.2 kcal/mol); the C-O bonds are longer, and the corresponding vibrational frequencies are significantly smaller than those of the other linear species. This cyclic species is not classified as an epoxy compound. State-state correlation analysis and the isomerization pathway searches have indicated that there are no direct correlations among three linear structures for each spin state, but they may interchange by experiencing two transition states and one cyclic intermediate. The easiest pathway is to break the Si-O bond to go to the linear SiCO, but its inverse process is very difficult. The most difficult process is to break the C-O bond and to go to the linear CSiO.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

安全反向代理服务器架设在真实网页服务器与用户浏览器之间靠近真实服务器的一侧,通过传输层安全协议保障用户与真实服务器之间的通信.作为基于传输层安全协议的虚拟专用网服务器的一个最重要的组成部分,安全反向代理有着极大的商业价值和技术含量.在FreeBSD-6.3的基础上设计并实现了一个与传统TCP/IP并行的TCP/IP跳转表.基于TCP/IP跳转表设计并实现了一种多加速卡调度算法.设计并实现了直接从加速卡队列获取数据包的代理转发协议栈.设计并实现了基于后台真实服务器反馈的负载均衡算法.测试表明,由这些算法和协议栈组成的高速安全反向代理服务器新进连接数达到了国内领先水平.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

卫星网络的固有特性如大时延、高误码、链路不对称和资源匮乏等特点, 使得TCP/IP协议无法为卫星网络提供令人满意的服务,因此设计适应卫星网络的特点新型网络协议以是一个值得深入研究的问题。采用跨层设计思想可以减少层次网络的冗余性,实时获取网络状态信息,通过调整数据传输方式,使得网络具有自适应性,并能显著提高卫星网络的性能。本文提出了基于跨层的卫星网络协议SaclTCP,它针对TCP协议的拥塞控制策略提出改进:在物理层将链路有效带宽信息反馈给传输层,使传输层了解物理链路容量的大小,准确的设定拥塞窗口门限阈值;在数据链路层将链路丢包事件通知给传输层,使传输层对丢包原因做出正确的判断;在网络层对路由器缓冲队列进行管理,一方面以一定的概率发送显示拥塞通知,另一方面计算网络拥塞状况,传输层利用这些信息动态调节拥塞窗口的大小。最后,在NS-2环境下对SaclTCP仿真,并与传统TCP协议进行比较。实验结果表明,SaclTCP协议在传输性能上有大幅度提高,更适合卫星网络环境,同时也证明了基于跨层的卫星网络协议设计的正确性和可行性。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We report a quantum-chemical study of electronic, optical and charge transporting properties of four platinum (II) complexes, pt((CN)-N-Lambda)(2) ((CN)-N-Lambda=phenylpyridine or thiophenepyridine). The lowest-lying absorptions at 442, 440, 447 and 429 nm are all attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-centered (LC) pi - pi(*) transition. While, unexpectedly, the lowest-lying phosphorescent emissions at 663, 660, 675 and 742 nm are mainly from metal-to-ligand charge transfer ((MLCT)-M-3) ligand-centered (LC) pi ->pi* transition. Ionization potential (IP), electron affinities (EA) and reorganization energy P (lambda(hole/electron)) were obtained to evaluate the charge transfer and balance properties between hole and electron.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

与Ti、Co。等催化体系相比, 稀土催化体系制备的丁二烯异戊二烯共聚物具有高顺1, 4结构, 分子链线性程度高, 几无支化;结晶能力随Ip含量的上升而下降, 耐低温性能优良;与天然橡胶相容性良好, 广泛应用于公路运输、航空航天、防震等领域。本文对实验室合成的5种不同Bd/Ip质量比的共聚胶的性能进行了研究。结果表明, 随Ip含量的增加, 胶样的门尼黏度、最小、最大转矩值逐渐升高, 硫化速率则在Bd/Ip为85/15~80/20时出现最低值, 耐压 缩疲劳及耐磨性能呈下降的趋势;玻璃化转变温度(Tg)随Ip比例增加而升高。相对于顺丁橡胶(BR)和异戊橡胶(IR),NdBIR 的耐低温性能有很大的提高, 当Bd/Ip质量比50/50时,NdBIR具有较平衡的滚动阻力和抗湿滑性。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The electron affinities and ionization potentials of 4d and 5d transition metal atoms were studied by CCSD(T), MP2 and density functional methods. The calculated results indicate that density functional method B3LYP has the best overall performance in predicting both electron affinity and ionization potential. SVWN gives largest IP and EA for 4d and 5d atoms. For the two basis sets used in this study, LANL2DZ and SDD, the performance of B3LYP/SDD combination is better than B3LYP/LANL2DZ, in particular for electron affinity calculation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The electrochemical polymerization of 0.01 M aniline in 1 M H2SO4 aqueous solution on roughened Au surface modified with a self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) has been investigated by in situ electrochemical surface-enhanced Raman scattering spectroscopy (SERS). The repeat units and possible structures of the electrodeposited polyaniline (PANI) film were proposed; i.e., aniline monomer is coupled in head-to-tail predominately at the C-4 of aniline and amine of 4-ATP, and the thin PANI film is orientated vertically to substrate surface. Simultaneous Raman spectra during potential scanning indicate clearly that the ultrathin PANI film (in initial growth of the film) consists of semiquinone radical cation (IP+), para-disubstituted benzene (IP and IP+) and quinine diimine (NP) while it is oxidized, and without quinine diimine and semiquinone radical cation while reduced. Meanwhile, the results confirm that 4-ATP monolayer shows a strong promotion on the electrodeposition of aniline monomer, and a possible polymerization mechanism was proposed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

以半经验分子轨道方法计算吲哚酚衍生物的分子结构参数.以主因子分析法和多元线性回归法研究了吲哚酚衍生物的式电位与其分子结构参数间的关系.研究发现,在所选择的19个分子结构参数中,双中心电子交换能(Eex(2)/eV),O -C键的共振能(Er(C1-O)/eV)和分子的电离势(Ip/eV)与其式电位有较好的相关性.其回归方程为:y=1.47×10-3Eex(2) -5.74×10-2 Er(C1-O) -1.41×10-2Ip(RC=0.9999,SD=0.00424).由分子结构与式电位关系及中间产物的稳定性可推测,在吲哚酚的氧化机理中氢的电离反应优先于电子转移过程.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

采用 Nd( naph) 3- Al( C2 H5) 3- ( t- C4 H9) Cl三组分稀土催化剂进行丁二烯 ( BD) -异戊二烯( IP)的顺式共聚合 ,在聚合过程中引入有机氯代烃 ( RCl) ,以与聚合液中的烷基铝作用生成阳离子活性种 ,引发已生成的共聚物的环化反应及单体的环聚反应 ,得到可溶性无凝胶且含有环聚成分的环化共聚合产物 .考察了 RCl用量、单体组成、稀土催化剂用量、反应温度等对原位环化反应的影响 .以红外光谱、核磁共振光谱对环化产物的结构进行了初步分析 ,确认了环化产物的生成

Relevância:

10.00% 10.00%

Publicador:

Resumo:

用循环伏安法对简单离子四乙基铵阳离子 (TEA+ )转移进行了研究。结果表明 :TEA+ 随微玻管内径减小 (小于 3μm) ,电流逐渐呈现拟稳态。随TEA+ 浓度减小 ,ip 值也减小。峰电流与扫描速度的平方根成正比 ,并且符合Randles Sevcik关系。同时讨论了微液 液界面TEA+ 体系简单离子的转移机理

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The polymerization of butadiene(Bd), isoprene(Ip) and styrene(St) has been examined using the six catalyst systems composed of lanthanocene, (C5H9Cp)(2)NdCl(I), (C5H9Cp)(2)SmCl(II), (MeCp)(2)SmOAr'(III), (Ind)(2)NdCl(IV), Me2Si(Ind)(2)NdCl(V) and (Flu)(2)NdCl(VI), and methylaluminoxane(MAO) respectively. All of them can be used to form the polyisoprene with molecular weights of 1 to 10 thousand and cis-1,4-unit contents of 41 to 47%. (I), (II) and (III) of them can be also used to form the polybutadiene with molecular weights of 10 to 20 thousand and cis-1,4-unit contents of 62 to 78%. In addition, the catalysts from (II) to (V) are still active for St polymerization and (II) of them gives a syndio -rich random polystyrene. It is noteworthy that (II) and (III) are active for homopolymerization of Bd, Ip and St in the same polymerization condition.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本体聚合与溶液聚合相比,具有能耗低,反应平稳,转化率高等特点。杨彩云等用稀土催化剂对异戊二烯(Ip)进行本体聚合,聚合转化率达80%以上,聚合物中无疑胶,且分子量分布较窄(M_w/M?<2)。本文报道和讨论本体聚合放大试验胶样的生胶特性。 异戊二烯胶样(BLn-IR)本所自制。溶液钛催化聚异戊二烯IR-1Q为日本JSR生产。天然橡胶(NR)系海南岛3~#烟片。门尼粘度按GB1232测定。应力-应变性能(23℃),用DL-1000B型电子拉力机测定,拉速500mm/min。玻璃化温度(T_g)用PE DSC-2C型仪测定,升温速率

Relevância:

10.00% 10.00%

Publicador:

Resumo:

采用5种充油量对稀土催化本体聚合丁二烯(Bd)-异戊二烯(Ip)共聚橡胶的加工工艺和硫化胶性能进行了研究。实验结果表明,随着充油量的增加,生胶ML值,屈服强度和拉伸强度均下降,可塑性增加,扯断伸长率变大,混炼行为变佳,胶料挤出性能由“劣”等转变为“中”等。硫化胶的扯断伸长率随充油量的增加而增大,而拉伸强度在充油量为30~40份时出现极大值,湿滑指数和拉伸耐寒系数随充油量的增加而增加,充油量超过20份后耐磨性能逐渐变好,充油量对硫化胶生热性能无明显影响。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

β-羧乙基锗倍半氧化物(Ge-132)的无毒广谱抗癌作用以及潜在的治疗艾滋病的功能~[1~3]促进了Ge-132及其衍生物合成及生物活性研究~[4~6],而对锗原子直接与苯环及其衍生物连接的有机锗倍半氧化物的研究则相对较少.我们曾报道了~[7]p-(二甲氨基)苯基锗倍半氧化物的合成、结构及对癌细胞的作用,p-(二乙氨基)苯基锗倍半氧化物的研究尚未见报道.本文采用改进的方法合成了p-(二乙氨基)苯基锗倍半氧化物(Ge-164).通过元素分析、IP、XPS和TG-DTA确定了组成和结构,观察了它对体外培养人乳腺癌细胞有丝分裂的影响.