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1.
2.
Surya K. De 《合成通讯》2013,43(16):2768-2774
Paal–Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of praseodymium(III) trifluoromethanesulfonate under solvent-free conditions has been accomplished with an excellent yield. This method is a very easy, rapid, and high-yielding reaction for the synthesis of N-substituted pyrrole derivatives. 相似文献
3.
Alexandre Westermann Christophe Geantet Philippe Vernoux Stphane Loridant 《Journal of Raman spectroscopy : JRS》2016,47(10):1276-1279
In this work, the origin of the Raman defects band at 570 cm−1 of praseodymium‐doped ceria was revisited from in situ spectra using six different exciting lines between 458 and 785 nm at low temperatures after oxidizing or reducing treatment. The observation of overtones and the fast change of relative intensity with excitation wavelength were explained by a resonance effect around 514 nm, which involved a Pr4+ containing defect stabilized at the oxidized state leading to an absorption band around 530 nm. The reduction of Pr4+ cations contained in such defects modifies the electronic properties of praseodymium doped ceria inhibiting the resonance effect. Additionally, the number of D1 defects that involved Pr3+ cations and oxygen vacancies increased allowing them to be distinguished. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
5.
We have found that it is possible to enhance the luminescence of Pr(III) in solutions of complexes with β-diketones: acetylacetone
derivatives containing fluoroalkyl substituents of different lengths and structures. We have established that in the presence
of organic solvents, second (additional) ligands, and surfactants shielding the central ion from the quenching effect of the
water molecules (OH oscillators), the intensity of luminescence for Pr(III) increases by a factor of 65, 38, and 45 respectively.
In this case, cationic surfactants form ionic associates with Pr(III) β-diketonates, with incorporation of one more β-diketone
molecule (ratio Pr:β-diketonate:surfactant = 1:4:1). As a result of suppression of intramolecular energy losses in solutions
of Pr(III) β-diketonates, it is possible to observe its rather intense luminescence at 605 nm (the transition 1D2 → 3H4), 612 nm (3P0 → 3H6), and 646 nm (3P0 → 3F2).
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 746–750, November–December, 2006. 相似文献
7.
J. Schneider D. Hauschild Ch. Frerichs L. Wetenkamp 《International Journal of Infrared and Millimeter Waves》1994,15(11):1907-1922
We report highly efficient CW fiber lasers at 2.7µm in an Er3+-doped and weakly Pr3+-codoped fluorozirconate fiber. The fiber lasers were pumped in three pump wavelength ranges around 650, 795 and 980 nm. Higher output powers of nearly 30 mW and a broader potential tuning range of 180 nm compared to Er3+ singly doped fiber lasers are demonstrated. Laser efficiencies of more than 13% were achieved. It is shown that the fiber laser can be tuned to longer wavelengths by increasing the pump power or, in certain cases, by increasing the pump wavelength. Furthermore, we present the wavelength tuning of the Er3+:Pr3+-codoped system by an external grating. The relationships between laser wavelength and pump rates are described, and the reasons for the improvements with Pr3+-codoping are given. 相似文献
8.
B. G. Bazarov V. G. Grossman R. F. Klevtsova A. G. Anshits T. A. Vereshchagina L. A. Glinskaya Yu. L. Tushinova K. N. Fedorov Zh. G. Bazarova 《Journal of Structural Chemistry》2009,50(3):566-569
Crystals of binary praseodymium and hafnium molybdate of Pr2Hf3(MoO4)9 composition are grown by solution-melt crystallization under spontaneous nucleation conditions. By the X-ray diffraction
data (X8 Apex automated diffractometer, MoK
α radiation, 2262 F(hkl), R = 0.0170) its composition and crystal structure are determined. Parameters of the trigonal unit cell are: a = b = 9.8001(1) ? c = 58.7095(8) ?, V = 4883.15(10) ?3, Z = 6, space group R
c. The crystal structure is composed of three types of polyhedra: MoO4 tetrahedra, HfO6 octahedra, and nine-vertex PrO9. All three types of polyhedra are bonded among themselves by common oxygen vertices of bridging MoO4 tetrahedra forming an openwork three-dimensional structure.
Original Russian Text Copyright ? 2009 by B. G. Bazarov, V. G. Grossman, R. F. Klevtsova, A. G. Anshits, T. A. Vereshchagina,
L. A. Glinskaya, Yu. L. Tushinova, K. N. Fedorov, and Zh. G. Bazarova
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Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 587–590, May–June, 2009. 相似文献
9.
合成了锑-镨与乙二胺四乙酸形成的新颖三维配合物[Sb2-μ4-(EDTA)2Pr(H2O)5]NO3•4H2O, 用元素分析、红外光谱、热分析及X射线单晶衍射法等进行了组成和结构表征. 结果表明该配合物属正交晶系, 空间群Pnn2; 晶胞参数: a=1.07031(2) nm, b=2.30805(4) nm, c=0.72343(2) nm, V=1.78711(7) nm3, Z=2, Dc=2.202 g/cm3, F(000)=1164, μ=2.955 mm-1, GOF=1.000, 最终偏离因子R1=0.0203, wR2=0.0545 [I>2σ(I)]. 在标题化合物中, 每个镨(III)离子的配位数为9, 与五个水分子中的五个氧原子和四个羧基氧原子配位, 形成三帽三角棱柱空间配位多面体. 锑(III)与EDTA离子中的四个氧原子和两个氮原子配位, 在赤道平面上有一孤对电子. 同时讨论了配合物的热分解过程. 相似文献
10.
Wang‐Ting Wu Feng‐Ying Chen Shui‐Yang He Huai‐Ming Hu Meng‐Lin Yang Yao‐Yu Wang 《中国化学》2006,24(5):711-713
The binuclear praseodymium(III) complex with N‐(1‐carboxyethylidene)‐salicylhydrazide (C10H10N2O4, H2L) was prepared in H2O‐C2H5OH mixed solution, and the crystal structure of [Pr2L2(HL)2(H2O)4]·3H2O·C6H6 was determined by X‐ray single crystal diffraction. The crystal complex crystallizes in the triclinic system with space group P‐1, and in the structure each Pr atom is 9‐coordinated by carboxyl O and acyl O and azomethine N atoms of two tridentate ligands to form two stable five‐membered rings sharing one side in keto‐mode and two water molecules. The coordination polyhedron around Pr3+ was described as a monocapped square antiprism geometry. In an individual molecule, four tridentate ligands were coordinated by two negative univalent (HL) and two bivalent forms (L) respectively. Two negative univalent ligands were coordinated via μ2‐bridging mode. 相似文献