57 resultados para (R)-N-(2-(diphenylphosphino)benzylidene)-1-((S)-2-(diphenylphosphino)ferrocenyl)ethylamine


Relevância:

100.00% 100.00%

Publicador:

Resumo:

描述了采自中国浙江九龙山的苔类植物一新种——毛茎合叶苔Scapania paraphyllia T.Cao,C.Gao,J.Sun & B.R.Zuo。该新种与腋毛合叶苔S.bolanderi Aust.相近,两种皆具带齿叶片和假鳞毛,但新种具如下特征可与腋毛合叶苔区别:(1)植物体小,通常红色;(2)假鳞毛多数,不分枝,不仅生于叶腋,茎上也有着生;(3)背脊为腹瓣长的1/4–1/3,背瓣为腹瓣大小的1/2–1/3;(4)叶角质层表面粗糙,具粗瘤,直径达6–8μm。与另一个相似种S.ampliata Steph.相比,因新种具有粗糙的叶表面和假鳞毛等特征,也易于区别。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We investigate the structural stability and electronic properties of ordered perovskite-type compounds Ba2MIrO6 (M = La, Y) by use of density functional theory. Cubic (Fm-3m), rhombohedral (R-3) and monoclinic (P2(1)/n) phases are considered for each compound. It was found that the most energetically stable phase for Ba2YIrO6 and Ba2LaIrO6 is P2(1)/n andR-3, respectively. It is also interesting to find that Ba2YIrO6 in R-3 phase, which was not reported in experiment, has a slightly lower energy than experimentally observed cubic Fm-3m phase.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The title heteropoly blue, (Bu4N)(6)H-10 [(PMo11MoO40)-Mo-VI-O-V](4) . H2O has been photochemically synthesized and characterized with elemental analysis, solid diffusion reflectance electronic spectra, CV, ESR, XPS, IR spectra, conductivity measurement and X-ray single crystal analysis. The crystallographic data for C96H218Mo48N6O169P4 are as follows: M-r = 8889.76, triclinic, P (1) over bar, a = 1.4142 (3) nm, b = 2.6027 (5) nm, c = 2.6403(5) nm, alpha = 113.96(3)degrees, beta = 90.05(3)degrees, gamma = 105.71(3)degrees, V = 8.481 (3) nm(3), Z = 1, D-c = 1.741 g/cm(3), F (000) = 4264, mu = 1.798 mm(-1). The X-ray crystal structure analysis reveals that there Is one independent molecule in the unit cell of the title heteropoly blue which contains four mixed-valence heteropoly anions, six tetrabutylammonium cations and one water molecule. Its molecular structure possesses a centrosymmetrical arrangement in the unit cell. The phosphorus atom is In the crystallographic inversion center of the heteropoly anion and the eight oxygen atoms surrounding central phosphorus atom comprise of a distorted hexahedron. Heteropolyanion has two equal sets of PO4 tetrahedron. The PO4 tetrahedron and the MoO6 octahedron in the polyanion are greatly distorted.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

3-[(4-Amino-2-methyl-5-pyrimidinyl)-methyl]-5-hydroxyethyl-4-methylthiazolium bromide sesquihydrate, C12H17N4OS+.Br-.1.5H2O, M(r) = 372.28, monoclinic, P2(1)/a, a = 11.676 (2), b = 24.819(7), c = 12.344 (3) angstrom, beta = 113.74(2)-degrees, V= 3274 (1) angstrom3 , Z = 8, D(x) = 1.51 g cm-3 (Mo Kalpha) = 0.71069 angstrom, mu = 26.2 cm-1, F(000) = 1528, T 293 K, R = 0.062 for 2720 observed reflections. Both the independent thiamine molecules A and B in the asymmetric unit adopt the common F conformation. A bromide anion is held by four neighbouring thiamine molecules through C(2)-H...Br hydrogen bonds and Br ... thiazolium-ring electrostatic interactions. Another bromide anion (or a water molecule) bridges the pyrimidine and thiazolium moieties of molecule A (or B) through a hydrogen bond with the amino group and an electrostatic interaction with the thiazolium ring.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

C12H12I2Te4, M(r) = 920.44, monoclinic, P2(1)/n, a = 10.942 (2), b = 14.924 (2), c = 11.415 (2) angstrom, beta = 104.32 (1)-degrees, V = 1806.0 (5) angstrom 3, Z = 4, D(x) = 3.38 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 100.7 cm-1, F(000) = 1592, T = 294 K, R = 0.033 for 1828 observed reflections. One of the Te atoms is bonded to the two I atoms, which are on either side of the molecular plane. The Te-I distances are 2.963 (1) and 2.961 (1) angstrom, which means oxidation at the Te atom instead of at the C = C bonds.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

采用低温技术,用 X 射线单晶衍射法测定了标题化合物的结构.晶体属 P4/mnc 空间群,a=12.515(3),c=17.636(7),Z=2.用788个独立可观测反射精修所有结构参数得 R=0.061.钼钒磷杂多酸阴离子中,PO_4四面体是无序的,P—O 键长1.54.M(Mo,V)是6配位,M—O 键长1.62—2.48.K 是7配位,K—O 键长2.84—3.10.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A unified criterion is developed for initiation of non-cohesive sediment motion and inception of sheet flow under water waves over a horizontal bed of sediment based on presently available experimental data. The unified threshold criterion is of the single form, U-o = 2 pi C[1 + 5(T-R/T)(2)](-1/4), where U-o is the onset velocity of sediment motion or sheet flow, T is wave period, and C and T-R are the coefficients. It is found that for a given sediment, U-o initially increases sharply with wave period, then gradually approaches the maximum onset velocity U-o = 2 pi C and becomes independent of T when T is larger. The unified criterion can also be extended to define sediment initial motion and sheet flow under irregular waves provided the significant wave orbital velocity and period of irregular waves are introduced in this unified criterion.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

用高效液相色谱法测定青海栽培何首乌中的主要有效成分大黄素、大黄素甲醚等蒽醌类成分。采用kromasil C18柱(4.6mm i.d.×250mm,5μm);V(甲醇):V(水):V(H3PO4)=750:250:0.001为流动相,检测波长为254nm,流速为1mL/min,进样量10μL。用此方法测定青海栽培何首乌不同部位中的蒽醌类成分,大黄素和大黄素甲醚达到基线分离,线性范围分别为0.094~1.50/μg(r=0.9992),0.094~1.50/μg(r=0.9997),回收率分别为大黄素95%、大黄素甲醚102%。实验发现青海栽培何首乌块根中大黄素和大黄素甲醚成分较藤、叶中高,大黄素含量比大黄素甲醚含量高。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

目的:建立反相高效液相色谱法同时测定刺芒龙胆植物不同部位落干酸、獐牙菜苦苷、龙胆苦苷的含量。方法:采用ZORBAX SB-C18(250mm×4.6mm,5μm)色谱柱,流动相为甲醇-水(含0.04%磷酸)的比例25:75,流速1mL·min^-1,检测波长238nm,柱温30℃。结果:3种成分均达到基线分离,落干酸、獐牙莱苦苷、龙胆苦苷的线性范围分别为0.039~1.56μg(r=0.9998),0.0725~1.45μg(r=0.9999),0.061~1.225μg(r=0.9997);回收率为101.3%(RSD=2.6%),98.7%(RSD=3.1%,99.6%(RSD=1.2%)。结论:测定方法快速,结果准确、可靠。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

济阳坳陷CO2气藏主要发育在高青-平南深断裂中南段和阳信次级凹陷西北缘及商店火山岩穹隆构造内。气藏中CO2气体浓度为69%~97%,δ^13CCO2值为-5.67‰~-3.35‰,CH4/^3He值为(1.01~5.65)×10^8,^3He/^1He值为(2.80~4.49)×10^-6,即R/Ra为2.00~3.21,^40Ar/^36Ar值为317~1791,CO2/^3He值为(0.25~2.61)×10^9。以上地球化学数据表明,济阳坳陷气藏中CO2主要来源于地慢,且慢源CO2在成藏过程中有损失,或者有壳源CO2的加入,特别是部分碳酸盐岩变质成因CO2的加入。在对CO2气来源定性分析的基础上,还需要在各来源的定量区分和CO2气藏的成藏及其与岩浆活动的时空匹配关系等方面作进一步的研究.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

水母雪莲属菊科植物,为名贵中药材其主要活性成分为黄酮类化合物。为解决雪莲资源其中匮乏,本文开展了利用水母雪莲细胞培养生产黄酮类活性成分的可行性研究。 采用目视法从水母雪莲原始愈伤组织中筛选得到白色、黄色和红色3种细胞系,其中黄色系的黄酮含量最高。利用γ射线辐射处理从红色系得高产黄酮细胞系。 证明了多种理化因子对水母雪莲培养细胞中黄酮类合成的调控作用。研究发现,温度和光照对水母雪莲愈伤组织黄酮合成影响较大。25℃是最佳培养温度;红光促进愈伤组织生长,蓝光促进黄酮的合成;进一步研究表明:光调节黄酮代谢途径第一步所需酶苯丙氨酸裂解酶(PAL)活性,PAL活性被红光所抑制,被蓝光所促进。碳源、氮源、植物激素对愈伤组织生长和黄酮形成影响较为显著。对MS培养基成分进行调整得到M-13培养基,在M-13培养基上培养的愈伤组织生长量和黄酮产量比MS培养基分别提高33%和82%。 首次建立水母雪莲细胞悬浮培养体系。确定了水母雪莲细胞悬浮培养的最适培养条件和最适培养基成分组成。摇床转速 90~120 r/min、接种量 2.5~4.0gDW/L、接种物种龄 8~10 d 对黄酮合成有利。调整MS培养基成分得到适合于培养水母雪莲悬浮细胞的生长培养基G和黄酮合成培养基MP,从而使细胞生长量与黄酮产量分别长比MS培养基提高32%和70%。 应用2-L搅拌式生物反应器对水母雪莲细胞进行了悬浮培养。TLC和HPLC分析表明,水母雪莲细胞培养物能够形成2种黄酮活性成分金合欢素和高车前素。本论文对水母雪莲细胞培养生产药用活性成分作了基础性工作。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of hydrogenated silicon films near the threshold of crystallinity was prepared by very high frequency plasmaenhanced chemical vapor deposition (VHF-PECVD)from a mixture of SiH4 diluted in H-2. The effect of hydrogen dilution ratios R = [H-2]/[SiH4] on the microstructure of the films was investigated. The photoelectronic properties and stability of the films were studied as a function of crystalline fraction. The results show that the diphasic films gain both the fine photoelectric properties like a-Si: H and high stability like mu w-Si:H. By using the diphasic silicon films as the intrinsic layer, p-i-n junction solar cells were prepared. Current-voltage (J-V) characteristics and stability of the solar cells were measured under an AM1.5 solar simulator. We observed a light-induced increase of 5.2% in the open-circuit voltage (V-oc) and a light-induced degradation of similar to 2.9% inefficiency.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Good quality hydrogenated protocrystalline silicon films were successfully prepared by radio frequency plasma enhanced chemical vapor deposition (PECVD) with various hydrogen dilution ratios (R = ([H-2]/[SiH4]) from 10 to 100). The photosensitivity of the films is up to 10(6) under the light intensity of 50mW.cm(-2). The microstructure of the films was studied by micro-region Raman scattering spectra at room temperature. The deconvolution of the Raman spectra by Gaussion functions shows that the films deposited under low hydrogen dilution ratios (R < 33) exhibit typical amorphous properties, while the films deposited under high hydrogen dilution ratios (R > 50) possess a diphasic structure, with increasing crystalline volume fraction with R. The size of the crystallites in the diphasic films is about 2.4 mm, which was deduced from the phonon confinement model. The intermediate range order of the silicon film increases with increasing hydrogen dilution ratio.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

非线性光学材料由于在信息技术中的应用前景而成为人们研究的热点,虽然有机材料有较高的光吸收和光学非线性,但由于其热稳定性和光稳定性差,难以实用化。利用金属纳米颗粒所具有的非线性光学效应制备有机/无机纳米杂化材料为解决这些问题开辟了新的方向。本文以两亲性的嵌段共聚物在选择性溶剂中形成的胶束为模板制备嵌段共聚物/金纳米杂化材料和嵌段共聚物/聚毗咯/金纳米杂化材料,使用TEM, UV一vi:吸收光谱、FT一工R以及WARD等手段对这些材料进行了表征。研究发现,使用紫外线还原法得到的杂化材料中金纳米颗粒尺寸分布窄、颗粒间排布规整;通过调整无机物前体加入的量得到不同粒径的金纳米颗粒(2一6nm);以不同的嵌段共聚物为模板可以实现对杂化材料中纳米颗粒尺寸和间距佩狗控制。在所制得的嵌段共聚物/聚砒咯/金纳米杂化材料中,极微小的金颗粒被反应中所生成的聚毗咯包裹。聚毗咯层的存在可以改变金纳米颗粒表面和附近的电场性质,这种材料可能具有很好的非线性光学性能。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

pH指示剂在高分子载体上的固定化研究是应光导纤维pH传感器的发展要求而发展起来的新的研究领域。pH指示剂在高分子固态载体上的固定直接决定着光导纤维pH传感器的灵敏度、响应时间、寿命等性能。迄今,吸附、包埋和化学键合三利,固定方法已得到广泛应用。吸附法与包埋法简单易行,但因指示剂易于逸出而无法保证试剂相的使用稳定性及寿命;化学键合法目前仅限于对含氨基等高反应活性基团的指示剂固定。另外,这三种固定技术均存在试剂相与分析对象呈现固/液两相分离的问题,它严重制约了传感器响应性能,成为pH指示剂固定技术发展的“瓶颈”。改善、发展与寻找新的指示剂/载体固定配对体系已成为本领域的研究焦点。本论文针对上述问题,开拓与发展了一系列指示剂固定于固态高分子载体上的新体系。(一)首先开拓与发展了酚红/交联聚乙烯醇与邻甲酚红/交联聚乙烯醇固定对的新体系。在酸性条件下,以甲醛做交联剂,通过在玻璃板上倾涂聚乙烯醇甲醛的凝胶溶液制备了高亲水性的交联聚乙烯醇载体膜;然后采用接枝共聚反应将丙烯酞胺单体与通过酸碱反应接枝有酚红或邻甲酚红的丙烯酞胺混合物接枝固定到交联聚乙烯醇薄膜上,首次将不含氨基的酚红、邻甲酚红在高亲水性的聚乙烯醇载体上固定。利用紫外可见光光谱仪测试了其响应性能。结果表明,固定化指示剂的光谱行为与其相应的水溶液的光谱行为不一致,这可能是固定化过程中新的化学键生成以及载体与指示剂之间的相互作用如氢键的作用等引起的。这也导致了其pH响应范围与相应指示剂水溶液的响应范围的差异。固定酚红交联聚乙烯醇pH敏感膜的pH响应范围为pH=6.72~8.49;固定邻甲酚红交联聚乙烯醇pH敏感膜的两个响应范围分别为[H~+]=0.1mol/L~5mol/L和pH7.97~12.26。这种方式制备的这两种pH敏感薄膜均表现出优异的可重复使用性、可逆性、稳定性及易于制备的特点。更突出的优点在于,与以聚丙烯酰胺为基质直接固定酚红的薄膜(PAM-PR)相比,这种固定技术制备的敏感膜,当其与分析剂溶液接触时,其接枝于表面的水溶性高分子溶解,呈现“液态”,在固态基质表面形成一“液膜”层,从而消除了试剂相与分析剂之间的相界面,克服了指示剂固定化技术中的“瓶颈”问题,大幅度地提高了其响应速度与灵敏度,使响应时间从PAM-PR的数十分钟降至30秒以下。(二)开拓了刚果红醋酸纤维素包埋对的pH敏感膜(CCM)及刚果红/环氧氯丙烷交联聚乙烯醇(PECM)和甲醛交联聚乙烯醇(PFCM)的三种pH敏感膜新体系,测试并比较了三种膜的响应性能。结果表明,固定化刚果红的光谱性质和响应范围与刚果红水溶液不一致,而且用不同载体固定的刚果红的光谱特征与响应范围也各不相同。CCM的响应范围为pH=2.5~4.5,PECM的响应范围在[H~+]=2mol/L~pH=6.8之间,PFCM响应范围为pH=2.90~5.48。这也可能是固定化过程中的氢键效应、空间位阻、指示剂与载体间发生的化学反应不同及载体本身结构的差异等引起的。这三种膜也具有良好的重现性、可逆性及响应迅速(平均响应时间低于25秒)的特点。另外发现醋酸纤维素包埋刚果红的敏感膜具有特殊的稳定性。对这种特殊的稳定性原因的分析表明选择合适尺寸分子的指示剂与载体配对将可能克服包埋技术中指示剂逸出的缺点。(三)对制备的pH敏感膜及对应的水溶液的pH线性响应范围给出了相应的线性回归方程(R>98.2)。结果表明这些敏感膜对响应范围内的pH均具有良好的线性响应关系。这些结果与思想不仅丰富了光导pH传感器的试剂相内容,也为后续工作提供了一些有益的借鉴。