首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The nu(12) band of trans-d(2)-ethylene (trans-C(2)H(2)D(2)) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 1240-1360 cm(-1) by Fourier transform infrared (FTIR) spectroscopy. This band was found to be relatively free from any local frequency perturbations. By fitting a total of 1185 infrared transitions of nu(12) with a standard deviation of 0.00043 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation, a set of accurate rovibrational constants for v(12) = 1 state was derived. The nu(12) band is A type with a band center at 1298.03797 +/- 0.00004 cm(-1). Copyright 2000 Academic Press.  相似文献   

2.
The complex [Fe(H2O)6]SiF6 is one of the most stable and best characterized high-spin Fe(II) salts and as such, is a paradigm for the study of this important transition metal ion. We describe high-frequency and -field electron paramagnetic resonance studies of both pure [Fe(H2O)6]SiF6 and [Zn(H2O)6]SiF6 doped with 8% of Fe(II). In addition, frequency domain magnetic resonance spectroscopy was applied to these samples. High signal-to-noise, high resolution spectra were recorded which allowed an accurate determination of spin Hamiltonian parameters for Fe(II) in each of these two, related, environments. For pure [Fe(H2O)6]SiF6, the following parameters were obtained: D=+11.95(1) cm(-1), E=0.658(4) cm(-1), g=[2.099(4),2.151(5),1.997(3)], along with fourth-order zero-field splitting parameters: B4(0)=17(1)×10(-4) cm(-1) and B4(4)=18(4)×10(-4) cm(-1), which are rarely obtainable by any technique. For the doped complex, D=+13.42(1) cm(-1), E=0.05(1) cm(-1), g=[2.25(1),2.22(1),2.23(1)]. These parameters are in good agreement with those obtained using other techniques. Ligand-field theory was used to analyze the electronic absorption data for [Fe(H2O)6]SiF6 and suggests that the ground state is 5A1, which allows successful use of a spin Hamiltonian model. Density functional theory and unrestricted Hartree-Fock calculations were performed which, in the case of latter, reproduced the spin Hamiltonian parameters very well for the doped complex.  相似文献   

3.
Electron paramagnetic resonance (EPR) study of Fe3(+) ions doped strontium nitrate (SN) single crystals is performed at liquid nitrogen temperature and at X band frequency. The spin Hamiltonian (SH) parameters are determined from the resonance lines observed at different angular rotations. The crystal field parameters (CFPs) are evaluated using superposition model of Newman. The Zeeman g-factor and zero-field splitting parameters (ZFSPs) of Fe3(+) ion in SN (truncated SH considered) are: g=1.9989 ± 0.002 and ∣D∣=(338 ± 5) × 10?? cm?1, ∣E∣=(10 ± 5)× 10?? cm?1, a=(458 ± 5)× 10?? cm?1, respectively. The Fe3(+) ion enters the lattice substitutionally replacing the Sr2(+) sites of cubic symmetry. The local site symmetry of Fe3(+) ion in the crystal is orthorhombic (lower than that of the host). The optical absorption study of the crystal is also done at room temperature in the wavelength range 195-925 nm. The energy values of different orbital levels are determined. The observed bands are assigned as transitions from the (6)A?(g)(S) ground state to various excited states of Fe3(+) ion in a cubic crystal field approximation. The observed band positions are fitted with four parameters, the Racah interelectronic repulsion parameters (B and C), the cubic crystal field splitting parameter (Dq) and the Trees correction (α) yielding: B=934, C=2059, Dq=1450, and α=90 (in cm?1). On the basis of EPR and optical data, the nature of metal-ligand bonding in this crystal is discussed. The ZFSPs are also determined theoretically using microscopic SH theory based on perturbation theory and CFPs, B(kq) obtained from superposition model. The values of ZFSPs thus obtained are ∣D∣=(340 ± 5) × 10?? cm?1 and ∣E∣=(15 ± 5) × 10?? cm?1.  相似文献   

4.
The spectrum of the nu(9) fundamental band of ethylene-d(4) (C(2)D(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 2300-2400 cm(-1) using a Fourier transform infrared spectrometer. A total of 549 transitions have been assigned and fitted using a Watson's A-reduced Hamiltonian in the I(r) representation to derive rovibrational constants for the upper state (v(9) = 1) up to five quartic terms with a standard deviation of 0.00087 cm(-1). They represent the most accurate rovibrational constants for the nu(9) band so far. About 30 transitions of K(a)(') = 0, one transition of nu(9) which were identified to be perturbed possibly by the nearby nu(11) and nu(2) + nu(12) transitions, were not included in the final fit. The nu(9) band of C(2)D(4) was found to be basically B-type with an unperturbed band center at 2341.836 94 +/- 0.000 13 cm(-1). Copyright 2000 Academic Press.  相似文献   

5.
Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO(2) reveal that the antiferromagnetic transition observed at T(N1) = 14 K might be induced by an R3m --> pseudoproper ferroelastic transition. In that case, the group theory states that the order parameter associated with the structural transition must belong to a two-dimensional irreducible representation E(g) (x(2) - y(2), xy). Since this type of transition can be driven by a Raman E(g) mode, we performed Raman scattering measurements on CuFeO(2) between 5 and 290 K. Considering that the isostructural multiferroic compound CuCrO(2) might show similar structural deformations at the antiferromagnetic transition T(N1) = 24.3 K, Raman measurements have also been performed for comparison. At ambient temperature, the Raman modes in CuFeO(2) are observed at ω(E(g)) = 352 cm(-1) and ω(A(1g)) = 692 cm(-1), while these modes are detected at ω(E(g)) = 457 cm(-1) and ω(A(1g)) = 709 cm(-1) in CuCrO(2). The analysis of the temperature dependence of the modes in both compounds shows that the frequencies of all modes increase with decreasing temperature. This typical behavior is attributed to anharmonic phonon-phonon interactions. These results clearly indicate that none of the Raman active modes observed in CuFeO(2) and CuCrO(2) drive the pseudoproper ferroelastic transitions observed at the Néel temperature T(N1). Finally, a broad band at about 550 cm(-1) observed in the magnetoelectric phase of CuCrO(2) below T(N2) could be associated with magnons.  相似文献   

6.
对 Ga N直纳米线的拉曼光谱及光致发光光谱进行了研究。拉曼光谱表明 ,与计算值相比 ,E2 ( high)声子频率在 560 cm- 1有 -9cm- 1的移动 ,这种声子频率显示出向低能带频移及带变宽的特征 ,是由于纳米尺寸效应所引起的结果。体系的光致发光光谱在 3 44 .8nm附近的近带隙发光 ,与文献报道的 Ga N体材料的数值3 65nm相比有一蓝移 ,这是由于量子限制效应造成的  相似文献   

7.
The nu(2) (A(1), 710.157 cm(-1)) and nu(5) (E, 701.717 cm(-1)) fundamental bands of D(3)(28)SiF have been studied by FTIR spectroscopy with a resolution of 2.4 x 10(-3) cm(-1). We assigned 1648 lines for the parallel band (J(max) = 50, K(max) = 21), 4279 for the perpendicular band (J(max) = 52, K(max) = 27), and in addition 671 perturbation-allowed transitions (J(max) = 50, K(max) = 12). The nearly degenerate v(2) = 1 and v(5) = 1 states are linked by (DeltaK = +/-1, Deltal = +/-1) and (DeltaK = +/-2, Deltal = -/+1) interactions, while the l(5) = +/-1 levels of nu(5) interact also by l(2, -1), l(2, 2), and l(2, -4) interactions. The first model with 36 free parameters, taking into account all these resonances through a nonlinear least-squares program, gave standard deviations of 1.56 x 10(-4) cm(-1) for 5997 nonzero-weighted IR data and 138 kHz for 8 MW data from the literature. The second model, in which the main Coriolis term was constrained to a force field value, used 37 parameters and gave similar standard deviations. A new determination of the A(0) and D(0)(K) ground state parameters was performed by two methods: either using differences between "forbidden" transitions differing by 3 in K or letting A(0) and D(0)(K) free in the global fit. The values obtained are fully compatible with those obtained previously by the "loop method." Copyright 2000 Academic Press.  相似文献   

8.
Two-dimensional (2D) correlation spectroscopy is a powerful method to study the intermolecular interactions between different molecules/functional groups. In the present paper, variable concentrations were selected to construct 2D synchronous spectrum for studying the weak intermolecular interactions in solutions. Mathematical analysis performed on 2D synchronous spectra using variable concentration as an external perturbation shows that the "Orthogonal Sample Design Scheme" is necessary for eliminating the interfering cross peaks in 2D synchronous spectra. The authors prepared four mixed-solutes-solutions whose concentration series satisfy the "Orthogonal Sample Design Scheme" for each chemical system and the consequent 2D synchronous spectrum was calculated from the corresponding four 1D spectra. Thus, by 1D & 2D FTIR spectra together with solid grinding reaction, the intermolecular interactions in two chemical systems (Sodium 2-Aminobenzoate/NdCl3 in aqueous solution, and 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (PC88A)/Naphthenic Acid (NA) in heptane solution) were studied, where the intermolecular interactions only induce subtle spectral variations in conventional 1D spectra. First, the cross peaks between f-f transition bands of Nd3+ ion at 521, 574, 741, 795 and 865 nm and pi-pi transition band of Sodium 2-Aminobenzoate at 308 nm in 2D synchronous spectrum confirm the coordination interaction between Sodium 2-Aminobenzoate and Nd3+. Solid grinding reaction between Sodium 2-Aminobenzoate and NdCl3 and FTIR spectra of the product indicate that the vibration bands of amino, carboxyl groups from sodium 2-aminobenzoate show considerable changes. Based on the spectral result above, a conclusion is drawn that Nd3+ can coordinate with Sodium 2-Aminobenzoate by amino and carboxyl groups. Second, the cross peaks between POH stretching band of PC88A at 983 cm(-1) and COOH stretching band of NA at 1 710 cm(-1) in 2D spectra confirm the interaction between PC88A and NA. Subtraction spectrum demonstrates that when PC88A is mixed with NA in heptane solution, and P=O stretching band of PC88A shifts from 1 199 to 1161 cm(-1), and POH stretching band shifts from 983 to 965 cm(-1). Based on the spectral result above, a conclusion was made that PC88A and NA can interact with each other by forming new assemblies with POH and COOH groups.  相似文献   

9.
[1]R. Casalbuoani, A. Deandrea, and M. Oertel, JHEP 032(2004) 0402. [2]G. Hooft, In Search of the Ultimate Building Blocks, Cambridge University Press, Cambridge (1997). [3]J. Belazey, Searches for New Physics at Hadron Coliders,Northern Illinois University (2005). [4]N. Arkani-hamed, A.G. Cohen, and H. Georgi, Phys. Lett.B 513 (2001) 232 [hep-ph/0105239]. [5]I. Low, W. Skiba, and D. Smith, Phys. Rev. D 66 (2002)072001 [hep-ph/0207243]. [6]N. Arkani-hamed, A.G. Cohen, E. Katz, and A.E. Nelson,JHEP 0207 (2002) 304 [hep-ph/0206021]. [7]N. Arkani-hamed, A.G. Cohen, E. Katz, A.E. Nelson, T.Gregoire, and J. G. Wacker, JHEP 0208 (2002) 021 [hepph/0206020]. [8]T. Gregoire and J.G. Wacker, JHEP 0208 (2002) 019[hep-ph/0206023]. [9]For a recent review, see e.g., M. Schmaltz, Nucl. Phys. B (Proc. Suppl.) 117 (2003) 40. [10]N. Arkani-hamed, A.G. Cohen, T. Gregoire, and J.G.Jacker, JHEP 0208 (2002) 020 [hep-ph/0202089]. [11]or a recent review, see e.g., M. Schmaltz, Nucl. Phys.Proc. Suppl. 117 (2003) 40 [hep-ph/0210415]. [12]E. Katz, J. Lee, A.E. Nelson, and D.G. Walker, hepph/0312287. [13]M. Beneke, I. Efthymiopoulos, M.L. Mangano, et al., hepph/0003033. [14]D.O. Carlson and C.-P. Yuan, hep-ph/9211289. [15]R. Frey, D. Gerdes, and J. Jaros, hep-ph/9704243. [16]G. Eilam, J.L. Hewett, and A. Soni, Phys. Rev. D 44(1991) 1473; W.S. Hou, Phys. Lett. B 296 (1992) 179; K.Agashe and M. Graesser, Phys. Rev. D 54 (1996) 4445;M. Hosch, K. Whisnant, and B.L. Young, Phys. Rev. D56 (1997) 5725. [17]C.S. Li, R.J. Oakes, and J.M. Yang, Phys. Rev. D 49(1994) 293, Erratum-ibid. D 56 (1997) 3156; G. Couture,C. Hamzaoui, and H. Koenig, Phys. Rev. D 52 (1995)1713; G. Couture, M. Frank, and H. Koenig, Phys. Rev.D 56 (1997) 4213; G.M. de Divitiis, et al., Nucl. Phys. B 504 (1997) 45. [18]B. Mele, S. Petrarca, and A. Soddu, Phys. Lett. B 435(1998) 401. [19]B. Mele, hep-ph/0003064. [20]J.M. Yang and C.S. Li, Phys. Rev. D 49 (1994) 3412,Erratum, ibid. D 51 (1995) 3974; J.G. Inglada, hepph/9906517. [21]L.R. Xing, W.G. Ma, R.Y. Zhang, Y.B. Sun, and H.S.Hou, Commun. Theor. Phys. (Beijing, China) 41 (2004)241. [22]L.R. Xing, W.G. Ma, R.Y. Zhang, Y.B. Sun, and H.S.Hou, Commun. Theor. Phys. (Beijing, China) 40 (2003)171. [23]T. Han, H.E. Logan, B. McElrath, and L.T. Wang, Phys.Rev. D 67 (2003) 095004. [24]I. Low, W. Skiba, and D. Smith, Phys. Rev. D 66 (2002)072001. [25]T. Han, H.E. Logan, B. McElrath, and L.T. Wang, hepph/0302188. [26]A.J. Buras, A. Poschenrieder, and S. Uhlig, hepph/0410309. [27]S. Eidelman, et al., Phys. Lett. B 592 (2004) 1. [28]F. Legerlehner, DESY 01-029, hep-ph/0105283.  相似文献   

10.
High-resolution FTIR spectra of 1,1,1-trifluoroethane (HFC-143a) have been recorded in the region from 1370 to 1470 cm(-1) with an unapodized resolution of 0.0016 cm(-1) at room temperature and of 0.004 cm(-1) at 183 and 100 K. The two main infrared active bands of A(1) symmetry have been shown to be nu(2) at 1407.5 cm(-1) and nu(4) + nu(5) at 1440.5 cm(-1). With the aid of Raman spectra, the two infrared inactive bands of E symmetry in this spectra region have been shown to be nu(8) at 1457.5 cm(-1) and nu(6) + nu(9) at 1446.2 cm(-1). The nu(2) band was analyzed as an isolated band, whereas the nu(4) + nu(5) band was analyzed as part of the triad nu(4) + nu(5), nu(6) + nu(9), and nu(8). Copyright 2000 Academic Press.  相似文献   

11.
用最小二乘法拟合CH3D分子6428cm^-1附近振动带的138个能级,10个振动常数。振动分析阐明带为CH3分子C-D对称伸缩振动3V2态,并与局域模振动理论计算值进行了比较。  相似文献   

12.
The infrared spectrum of the nu(12) fundamental band of ethylene (C(2)H(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 1380-1500 cm(-1) using the Fourier transform technique. By assigning and fitting a total of 1387 infrared transitions using a Watson's A-reduced Hamiltonian in the I(r) representation, rovibrational constants for the upper state (v(12) = 1) up to five quartic and three sextic centrifugal distortions terms were derived. They represent the most accurate constants for the band so far. The rms deviation of the fit was 0.00033 cm(-1). The A-type nu(12) band with a band center at 1442.44299 +/- 0.00003 cm(-1) was found to be relatively free from local frequency perturbations. The inertial defect Delta(12) was found to be 0.24201 +/- 0.00002 u ?(2). Copyright 2000 Academic Press.  相似文献   

13.
We study J/ψ inclusive production in the decays of P-wave bottomoninm χbJ(1P, 2P) for J=0,1,2.Within the framework of the non-relativistic QCD (NRQCD) factorization method we calculate the contributious coming from four relevant processes including one color-singlet process and three color-octet ones,which are b(_b)(3pJ,(_1))→c(_c)(3S1,(_8))+c+(_c), b(_b)(3S1,(_8))→c(_c_(3S1,(_1))+g+g, b(_b)(3S1,(_8))→c(_c)(3S1,(_1))+c+(_c) and b(_b)(3S1,(_8))→c(_c)(3S1,(_8))+g. Our calculation shows that the color-octet processes, especially the gluon fragmentation one, contribute the most in the decays of χb0 and χb1. However, the J/ψ production in the χb2 decay is dominated by the color-singlet process. Furthermore, the gluon fragmentation process gives a δ function in the energy fraction distribution of J/ψ, which can be considered to be another characteristic for its identification.From our estimation the branching ratio for these processes is about 10-4-10-5, which indicates that J/ψ inclusive production is detectable at B-factories. Studying these processes would help us to gain a deeper understanding of the color-octet mechanism.  相似文献   

14.
The Fourier transform infrared (FTIR) spectrum of the nu(12) fundamental band of ethylene-(13)C(2) ((13)C(2)H(4)) was recorded with an unapodized resolution of 0.004 cm(-1) in the frequency range from 1380 to 1500 cm(-1). Rovibrational constants for the upper state (nu(12)=1) up to five quartic and three sextic centrifugal distortion terms were derived for the first time by assigning and fitting a total of 1177 infrared transitions using a Watson's A-reduced Hamiltonian in the I(r) representation. The rms deviation of the fit was 0.00045 cm(-1). The ground state rovibrational constants were also determined for the first time by a fit of 738 combination differences from the present infrared measurements, with a rms deviation of 0.00060 cm(-1). The A-type nu(12) band with a band center at 1436.65411+/-0.00005 cm(-1) was found to be relatively free from local frequency perturbations. The inertial defect Delta(12) was found to be 0.24300+/-0.00002 u?(2). Copyright 2001 Academic Press.  相似文献   

15.
不同煤级煤的Raman谱特征及与XRD结构参数的关系   总被引:2,自引:0,他引:2  
11种Cdaf在57.58%~94.01%的不同变质程度煤的拉曼光谱实验表明不同变质程度煤的拉曼光谱一级模都存在两个明显的振动峰,分别为较为宽缓的D峰(1 340~1 380 cm-1)和相对较为尖锐的G峰(1 580~1 600 cm-1)。将800~1 800 cm-1范围的谱图拟合为两个洛仑兹峰,每个峰的峰位置,峰强度以及半峰宽等拉曼参数与碳含量的相关关系分析结果显示:D峰位置和G峰位置随碳含量的增加分别向低波数和高波数区域移动;两峰的峰位差随碳含量的增加而增加;两峰的半峰宽FWHM-D,FWHM-G及两峰强度比ID/IG在碳含量75%~94%范围内与碳含量线性相关。发现XRD分析获得的d002和Lc与拉曼谱中的G峰位置及半峰宽存在着良好的相关性。与X射线衍射得到的晶粒尺寸La值相关性分析表明用Cancado公式和KW公式对La进行估算均是不合理的。  相似文献   

16.
采用放电溅射出的镍原子与甲醇气体在超声射流条件下产生NiH分子,获得了NiH分子在15000~21400 cm-1的激光诱导荧光激发谱.首次报道了NiH分子在19000~21400 cm-1的光谱.将观测到的24个谱带归属到7个不同的电子跃迁,并对每个谱带进行了转动分析.观测到了A、B、D、E、F和G态的高振动能级,得到了这些电子态的振动频率、非谐性常数、转动常数和平衡键长等较完整的光谱常数.并重新标识了一些谱带.  相似文献   

17.
碳纳米管及其H_2吸附体系的Raman光谱   总被引:1,自引:0,他引:1  
利用紫外Raman光谱技术 ,对分别以CO和CH4为碳源、由化学催化法制备的两种多壁碳纳米管以及它们的H2 吸附体系进行Raman光谱表征 ,观测到可分别归属于类石墨结构的基频模G (1 5 80cm- 1 )和D (1 41 6cm- 1 ,缺陷诱导 ) ,以及它们的二阶和三阶组合频 2D(2 83 2cm- 1 ) ,D +G (2 996cm- 1 ) ,2G (3 1 6 0cm- 1 )和 2D +G (441 2cm- 1 )的Raman峰 ;H2在这些多壁碳纳米管上吸附有两种形式 :非解离吸附分子氢H2 (a)和解离吸附生成含氢表面物种CHX(x =3 ,2 ,1 ) ,所观测在 2 85 0 ,2 96 7和 3 95 0cm- 1 处的Raman谱峰可分别归属于表面CH2 基的对称C -H伸缩模 ,CH3基的不对称C -H伸缩模 ,以及吸附态分子氢H2 (a)的H -H伸缩模  相似文献   

18.
氮化铝结构的高温Raman光谱分析   总被引:2,自引:2,他引:0  
本文测量了氮化铝在不同温度下的Raman光谱 ,并确定了氮化铝的光学声子模E2 1、A1(TO)、E2 2 、E1(TO)、A1(LO)和E1(LO)Raman散射峰的频率 ,它们分别为 2 5 2cm- 1、6 1 4cm- 1、6 5 8cm- 1、6 72cm- 1、894cm- 1和 91 2cm- 1,其中光学声子模A1(TO)、E2 2 的Raman散射峰比较明显。随着温度的升高 ,A1(TO)、E2 2 散射峰的频率向低波数方向变化 ,表明氮化铝粉末压制体中存在的压应力逐渐减小 ;这两个散射峰的半高宽逐渐增大 ,说明随着温度的升高 ,存在氮原子和铝原子的扩散使得氮化铝粉末压制体中晶体结构逐渐发生变化。由于氮化铝粉末本身在空气中易与水蒸气发生反应 ,生成的Al(OH) 3 或AlOOH在加热过程会发生分解 ,干扰样品高温Raman光谱测量。  相似文献   

19.
实验测量了室温下磷酸二氢钾KH2PO4(KDP)晶体0.2~1.6THz的时域光谱,以及50~4000cm-1范围内的远红外光谱,200~2000nm的紫外-可见-红外光谱。KDP晶体的禁带宽度是5.91eV。在测量范围内有一个很宽的声子吸收带。从0.2~205.5THz吸收系数在35~80cm-1,声子吸收的低频端小于0.2THz。最高的纵光学模声子的频率νLO大约是205.5THz,由此求出这支声子的H—O键的力常数为13.13N·cm-1。  相似文献   

20.
[1]G.T.Bodwin,E.Braaten,and G.P.Lepage,Phys.Rev.D 51 (1995) 1125;[Erratum-ibid.D 55 (1997) 5853][arXiv:hep-ph/9407339]; J.Boltz,P.Kroll,and G.A.Schulre,Phys.Lett.B 392 (1997) 198; J.Boltz,P.Kroll,and G.A.Schulre,Phys.J.C 2 (1998) 705. [2]S.M.Wong,Nucl.Phys.A 674 (2000) 185; S.M.Wong,Eur.Phys.J.C 14 (2000) 643. [3]J.Z.Bai,Y.Ban,J.G.Bian,et al.,Phys.Rev.D 67 (2003)112001. [4]M.Jacob and G.C.Wick,Ann.Phys.7 (1959) 404. [5]S.U.Chung,Phys.Rev.D 48 (1993) 1225; S.U.Chung,Phys.Rev.D 57 (1998) 431; B.S.Zou and D.V.Bugg,Eur.Phys.J.A 16 (2003) 537. [6]Particle Data Group,Phys.Lett.B 592 (2004) pp.924-966. [7]M.A.Doncheski,et al.,Phys.Rev.D 42 (1990) 2293; E.Eichten,et al.,Phys.Rev.D 21 (1980) 203; K.J.Sebastian,Phys.Rev.D 26 (1982) 2295; G.Hardekopf and J.Sucher,Phys.Rev.D 25 (1982) 2938; R.McClary and N.Byers,Phys.Rev.D 28 (1983) 1692; P.Moxhay and J.L.Rosner,Phys.Rev.D 28 (1983) 1132. [8]B.S.Zou and F.Hussain,Phys.Rev.C 67 (2003) 015204.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号