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91.
92.
The silver-dppm complex, [Ag2(dppm)2(NMP)2](SbF6)2·4H2O·3CH2Cl2 1 (NMP = 2- (4-dimethylaminophenyl)imidazo(4,5-f)(1,10)phenanthroline, dppm = diphenylphosphinomethane), was synthesized and its structure was determined by X-ray diffraction. The crystal belongs to mono- clinic, space group C2/c, Mr = 2461.61, a = 21.57(10), b = 22.48(6), c = 22.53(6) (A), β = 101.29(2)o, V = 10713(64) (A)3, Z = 4, Dc = 1.526 g/cm3, μ = 1.141 mm-1, F(000) = 4920, R = 0.0664 and Wr = 0.1774 for 8524 observed reflections (I > 2σ(I)). Complex 1 exists as a centrosymmetric dimmer. The two dppm molecules bridge two AgNMP moieties to form an eight-membered Ag2P4C2 metal- lacyclic ring with ligand NMP chelating to each Ag. It appears photoluminescence λ(max = 625 nm) at room temperature and makes red shift compared with free ligand NMP λ(max = 522 nm). DFT calculation indicates that the emission of 1 originates from singlet metal-perturbed ILCT excited state. 相似文献
93.
The syntheses and the X-ray structures of the tetranuclear gold(I) benzamidinate, Au4[PhNC(Ph)NPh]4, and the tetranuclear gold(I) acetamidinate, Au4[PhNC(CH3)NPh]4, clusters are reported. The clusters are produced by the reaction of the sodium salt of an amidine ligand with the gold precursor
Au(THT)Cl in a (1:1) stoichiometry. The average Au...Au distance between adjacent Au(I) atoms is ∼2.9 ?, typical of compounds
having an aurophilic interaction. The four gold atoms are arranged in a square (Au...Au...Au... = 88–91°) in the acetamidinate
and in a distorted square (Au...Au...Au... = 82–97°) in the benzamidinate derivative. Electrochemical oxidation of the tetranuclear
complex Au4[PhNC(Ph)NPh]4 show three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s in CH2Cl2 similar to the three reversible waves seen before from the tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-4-Me, and Ar = C6H3-3,5-Cl. A summary of the chemistry of the tetranuclear Au(I) amidinate complexes Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, C6H3-3,5-Cl, C6H4-4-Me, C6H4-3-CF3, C6F5, C10H7 also is presented. The tetranuclear clusters Au4[ArNC(H)NAr]4, Ar = C6H4-4-OMe, Ar = C6H4-3-CF3, Ar = C6H4-4-Me and Ar = C6H4-3,5-Cl are the first tetranuclear gold(I) cluster species from group 11 elements to show fluorescence at room temperature.
The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes.
Recently it has been shown that Au4[ArNC(H)NAr]4 are very effective catalysts upon calcination for room temperature CO oxidation.
Congratulations to Dieter Fenske, a superb synthetic chemist with exceptional talents in cluster chemistry, on the occasion
of his 65th birthday. 相似文献
94.
近十几年来,对小分子过渡金属配合物与大分子DNA键合与识别机理的研究一直是国际上生物无机化学领域十分活跃的研究课题[1 ̄3],已发展了一系列具有特定功能的配合物,如DNA结构探针和DNA荧光探针等。与其他类型的金属配合物相比,八面体过渡金属多吡啶配合物具有丰富的光化学和光物理信息,当这些配合物与DNA相互作用时,由于结构匹配或微环境的差异,配合物的光谱特征会出现不同程度的改变,从而达到对DNA的检测。传统的DNA荧光探针有[Ru(bpy)2dppz]2 和[Ru(phen)2dppz]2 (bpy=2,2′-联吡啶,phen=1,10-菲咯啉,dppz=二吡啶[3,2-a∶2′,3′… 相似文献
95.
José A. Fernandes Susana S. Braga Rute A. Sá Ferreira Martyn Pillinger Luís D. Carlos Paulo Ribeiro-Claro Isabel S. Gonçalves 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):329-333
A 1:1 inclusion compound between octakis(2,3,6-tri-O-methyl)-γ-cyclodextrin (TRIMEG) and the chelate complex Eu(NTA)3·2H2O (NTA=1-(2-naphthoyl)-3,3,3-trifluoroacetonate) was prepared and characterized by powder X-ray diffraction, thermogravimetric analysis and photoluminescence spectroscopy. The results were compared with those obtained for the corresponding native γ-CD adduct. Excitation and emission spectra were measured, and the lifetimes were determined for the Eu3+ first excited state (5D0). The results indicate the presence of only one low-symmetry environment for the Eu3+ cations in the inclusion compounds. Encapsulation of the Europium complex in the two CDs increases the quantum efficiency of the ligand-to-metal energy transfer pathway, but the efficiency of the Eu3+ sensitization was significantly higher with TRIMEG as the host molecule. This may be related with the observation that the two hosts appear to have different influences on the Eu3+ coordination environments for the guest molecule. 相似文献
96.
B. V. Bukvetskii E. V. Fedorenko A. G. Mirochnik V. E. Karasev 《Journal of Structural Chemistry》2007,48(6):1148-1151
The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band. 相似文献
97.
Electronic structures of zinc and palladium tetraazaporphyrin derivatives controlled by fused benzo rings 总被引:1,自引:0,他引:1
Zinc and palladium tetracyclic aromatic complexes lying structurally between tetraazaporphyrin (TAP) and phthalocyanine (Pc), that is, monobenzo-, adjacently dibenzo-, oppositely dibenzo-, and tribenzo-fused TAPs, have been prepared, and their electronic structures investigated by electronic absorption, magnetic circular dichroism (MCD), fluorescence, phosphorescence, and time-resolved electron paramagnetic resonance (TREPR) spectroscopy, as well as cyclic voltammetry. The last-named indicated that the first oxidation potentials shift to more negative values with increasing number of the fused benzo rings, but also suggested that the first reduction potential apparently has no correlation with the size and symmetry of the pi-conjugated systems. However, this latter behavior is reasonably interpreted by the finding that the effect of the fused benzo rings on destabilization of the LUMO depends on the orbital to which they are fused (i.e., whether it is an egx or egy orbital), since the LUMOs of TAP complexes are degenerate with D4h symmetry. The energy splitting of the LUMOs, that is, DeltaLUMO, was evaluated experimentally for the first time by analyzing the relationship between the first reduction potential and the size and shape of the pi-conjugated system. Electronic absorption and MCD measurements indicate that the lowest excited singlet states are split in the case of the low-symmetry TAP derivatives, although these excited states are degenerate for Pc and TAP with D4h symmetry. These energy splittings DeltaE(SS) correlate well with the DeltaLUMO values. To investigate the electronic structures in the lowest excited triplet state, zero-field splitting (zfs) was analyzed by time-resolved EPR (TREPR) spectroscopy. The energy splitting in the lowest excited triplet state, DeltaE(TT) was quantitatively evaluated from the temperature dependence of the zfs or spin-orbit coupling of the Pd complexes. Consequently, it is demonstrated that DeltaLUMO, DeltaE(SS), and DeltaE(TT) values exhibiting a mutually good relationship can be determined experimentally. 相似文献
98.
An europium-sensitized time-resolved luminescence (TRL) method was developed to determine oxytetracycline (OTC) in cultivated catfish muscle. Extraction of OTC from fish muscle was performed with pH 4.0 ethylenediaminetetraacetic acid (EDTA)-McIlvaine buffer and clean up with hydrophilic-lipophilic balanced copolymer solid phase extraction (SPE) cartridges. The eluate was used without further concentration for TRL measurement in pH 9.0 micellar tris(hydroxylmethyl)aminomethane (TRIS) buffer. Cetyltrimethylammonium chloride (CTACl) was used as surfactant and EDTA as a co-ligand. The excitation and emission wavelengths were set at 388 and 615 nm, respectively. The linear dynamic range was 0-1000 ng g−1 (R2=0.9995). The recovery was 92-112% in the fortification range of 50-200 ng g−1 and the limits of detection (LOD) ranged from 3 to 7 ng g−1. Incurred catfish samples were used to demonstrate the performance of the method around 100 ng g−1, the European Union maximum residue level. 相似文献
99.
V. G. Luchina I. Yu. Sychev V. S. Marevtsev T. Ya. Vlasenko Yu. D. Khamchukov M. I. Cherkashin 《Russian Chemical Bulletin》1992,41(1):77-82
The influence of temperature and concentration on the spectral polarization properties of the luminescence and absorption of molecules of the original form of photochromic spiroanthrooxazine (SAO) in petroleum ether and polyethylene was investigated. It was shown that the long-wave part of the absorption spectra of the molecules is formed by at least two -*-type electronic transitions, the oscillators of which are mutually orthogonal. It is suggested that the SAO molecules form dimers in nonpolar media through dipole-dipole interaction, and at high concentrations they also form higher associates. Dimers stable in the ground state dissociate when excited to the second electronic transition with a rate constant of 1012–1013 s–1.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Department of the Institute of Solid-State Physics and Semiconductors, Academy of Sciences of Belarus, 211177 Vitebsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 99–106, January, 1992. 相似文献
100.
Assembly of [Ag(CN)2]^- units with M(Ⅱ)-diamine complex cations [Cu(LN-N)2]^2+, where LN-N represents L2-diaminopropane (pn) and ethylenediamine (en), afforded two complexes, [Cu(pn)2][Ag2(CN)4] (1) and [Cu(en)2][Ag3(CN)5] (2), which were characterized by elemental analysis, IR, UV-Vis and ESR spectra. Single crystal X-ray analyses show that these complexes have 2D and 3D architectures through silver-silver interactions and other weak interactions. The luminescence behaviors of the two complexes were also studied by means of emission spectra. 相似文献