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81.
Sebastian Scharf Eduard Kovalski Tobias Rüffer Alexander Hildebrandt Heinrich Lang 《无机化学与普通化学杂志》2020,646(22):1820-1833
The synthesis of [Ti6O4(OiPr)8(O2CPh)8] ( 3 ) and [RuCl(N≡CR)5][RuCl4(N≡CR)2] ( 4a , R = Me; 4b , R = Ph), [Ru(N≡CPh)6][RuCl4(N≡CPh)2] ( 5 ) and [H3O][RuCl4(N≡CMe)2] ( 7a ) is discussed. Crystallization of 5 from CH2Cl2 gave trans-[RuCl2(N≡CPh)4] ( 6 ). The solid-state structures of 3 , 4a , b , 5 , 6 and 7a are reported. Complex 4b forms a 3D network, while 6 displays a 2D structure, due to π-interactions between the benzonitrile ligands. The (spectro)electrochemical behavior of 4a , b and 6 was studied at 25 and –72 °C and the results thereof are compared with [NEt4][RuCl4(N≡CMe)2] ( 7b ) and [RuCl(N≡CPh)5][PF6] ( 8 ). The electrochemical response of the cation and the anion in 4a , b are independent from each other. [RuCl(N≡CR)5]+ possesses one reversible RuII/RuIII process. However, [RuCl4(N≡CMe)2]– was shown to be prone to ligand exchange and disproportionation upon formation of either a RuIV and RuII species at 25 °C, while at –72 °C the rapid conversion of the electrochemically formed species is hindered. In situ IR and UV/Vis/NIR studies confirmed the respective disproportionation reaction products of the aforementioned oxidation and reduction, respectively. 相似文献
82.
Victor Ch. Kravtsov Vasile Lozovan Nikita Siminel Eduard B. Coropceanu Olga V. Kulikova Natalia V. Costriucova Marina S. Fonari 《Molecules (Basel, Switzerland)》2020,25(23)
Eight mixed-ligand coordination networks, [Cd(2-aba)(NO3)(4-bphz)3/2]n·n(dmf) (1), [Cd(2-aba)2(4-bphz)]n·0.75n(dmf) (2), [Cd(seb)(4-bphz)]n·n(H2O) (3), [Cd(seb)(4-bpmhz)]n·n(H2O) (4), [Cd(hpa)(3-bphz)]n (5), [Zn(1,3-bdc)(3-bpmhz)]n·n(MeOH) (6), [Cd(1,3-bdc)(3-bpmhz)]n ·0.5n(H2O)·0.5n(EtOH) (7), and [Cd(NO3)2(3-bphz)(bpe)]n·n(3-bphz) (8) were obtained by interplay of cadmium nitrate tetrahydrate or zinc nitrate hexahydrate with 2-aminobenzenecarboxylic acid (H(2-aba)), three dicarboxylic acids, sebacic (decanedioic acid, H2seb), homophthalic (2-(carboxymethyl)benzoic acid, H2hpa), isophthalic (1,3-benzenedicarboxylic acid, H2(1,3-bdc)) acids, bis(4-pyridyl)ethane (bpe) and with four azine ligands, 1,2-bis(pyridin-4-ylmethylene)hydrazine (4-bphz), 1,2-bis(1-(pyridin-4-yl)ethylidene) hydrazine (4-bpmhz), 1,2-bis(pyridin-3-ylmethylene)hydrazine (3-bphz), and 1,2-bis(1-(pyridin-3-yl) ethylidene)hydrazine (3-bpmhz). Compounds 1 and 2 are 1D coordination polymers, while compounds 3–8 are 2D coordination polymers. All compounds were characterized by spectroscopic and X-ray diffraction methods of analysis. The solvent uptakes and stabilities to the guest evacuation were studied and compared for 1D and 2D coordination networks. The de-solvated forms revealed a significant increase of emission in comparison with the as-synthesized crystals. 相似文献
83.
Baptiste Joalland Nuwandi M. Ariyasingha Sren Lehmkuhl Thomas Theis Stephan Appelt Eduard Y. Chekmenev 《Angewandte Chemie (International ed. in English)》2020,59(22):8654-8660
Radio amplification by stimulated emission of radiation (RASER) was recently discovered in a low‐field NMR spectrometer incorporating a highly specialized radio‐frequency resonator, where a high degree of proton‐spin polarization was achieved by reversible parahydrogen exchange. RASER activity, which results from the coherent coupling between the nuclear spins and the inductive detector, can overcome the limits of frequency resolution in NMR. Here we show that this phenomenon is not limited to low magnetic fields or the use of resonators with high‐quality factors. We use a commercial bench‐top 1.4 T NMR spectrometer in conjunction with pairwise parahydrogen addition producing proton‐hyperpolarized molecules in the Earth's magnetic field (ALTADENA condition) or in a high magnetic field (PASADENA condition) to induce RASER without any radio‐frequency excitation pulses. The results demonstrate that RASER activity can be observed on virtually any NMR spectrometer and measures most of the important NMR parameters with high precision. 相似文献
84.
Yu. A. Avetisyan V. A. Malyshev E. D. Trifonov 《Journal of Experimental and Theoretical Physics》2020,130(3):380-386
Photon recoil upon light scattering by a Bose–Einstein condensate (BEC) of a dilute atomic gas is analyzed theoretically accounting for a weak interatomic interaction. Our approach is based on the Gross–Pitaevskii equation for the condensate, which is coupled to the Maxwell equation for the field. The dispersion relations of recoil energy and momentum are calculated, and the effect of weak nonideality of the condensate on the photon recoil is ubraveled. A good agreement between the theory and experiment [7] on the measurement of the photon recoil momentum in a dispersive medium is demonstrated. 相似文献
85.
Peptide synthesis in aqueous environments: the role of extreme conditions and pyrite mineral surfaces on formation and hydrolysis of peptides 总被引:1,自引:0,他引:1
Schreiner E Nair NN Wittekindt C Marx D 《Journal of the American Chemical Society》2011,133(21):8216-8226
A comprehensive study of free energy landscapes and mechanisms of COS-mediated polymerization of glycine via N-carboxy anhydrides (NCAs, "Leuchs anhydrides") and peptide hydrolysis at the water-pyrite interface at extreme thermodynamic conditions is presented. Particular emphasis is set on the catalytic effects of the mineral surface including the putative role of the ubiquitous sulfur vacancy defects. It is found that the mere presence of a surface is able to change the free energetics of the elementary reaction steps. This effect can be understood in terms of a reduction of entropic contributions to the reactant state by immobilizing the reactants and/or screening them from bulk water in a purely geometric ("steric") sense. Additionally, the pyrite directly participates chemically in some of the reaction steps, thus changing the reaction mechanism qualitatively compared to the situation in bulk water. First, the adsorption of reactants on the surface can preform a product-like structure due to immobilizing and scaffolding them appropriately. Second, pyrite can act as a proton acceptor, thus replacing water in this role. Third, sulfur vacancies are found to increase the reactivity of the surface. The finding that the presence of pyrite speeds up the rate-determining step in the formation of peptides with respect to the situation in bulk solvent while stabilizing the produced peptide against hydrolysis is of particular interest to the hypothesis of prebiotic peptide formation at hydrothermal aqueous conditions. Apart from these implications, the generality of the studied organic reactions are of immediate relevance to many fields such as (bio)geochemistry, biomineralization, and environmental chemistry. 相似文献
86.
A. G. Petersyan G. O. Shirinyan K. L. Ovanesyan A. A. Avetisyan 《Crystal Research and Technology》1978,13(1):43-46
Formation of {110} and {211} type facets in rare-earth aluminium garnet crystals grown along different crystallographic directions is analyzed and it is shown that D/2R parameter (where D is the crystal diameter and R is the curvature radius of spherical growth interface) may be used to characterize the number of originating facets and their configuration in crystals. 相似文献
87.
Dr. Eduard E. Karslyan Dr. Alexandra O. Borissova Prof. Dr. Dmitry S. Perekalin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(20):5676-5679
A polycyclic aromatic ligand for site-selective metal coordination was designed by using DFT calculations. The computational prediction was confirmed by experiments: 2,3,6,7-tetramethoxy-9,10-dimethylanthracene initially reacts with [(C5H5)Ru(MeCN)3]BF4 to give the kinetic product with a [(C5H5)Ru]+ fragment coordinated at the terminal ring, which is then transformed into the thermodynamic product with coordination through the central ring. These isomeric complexes have markedly different UV/Vis spectra, which was explained by analysis of the frontier orbitals. At the same time, the calculations suggest that electrostatic interactions are mainly responsible for the site selectivity of the coordination. 相似文献
88.
R. H. Avagyan A. E. Avetisyan I. A. Kerobyan S. P. Taroyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2009,44(5):250-255
A number of areas of development of applied studies at the Yerevan Physics Institute (YerPhI) are viewed. The main area is
research into possibilities to produce radio nuclides for nuclear medicine on the linear accelerator of electrons at YerPhI.
We consider also the methods for employment of neutron beams obtained from photonuclear reactions for boron-capture neutron
therapy and for nondestructive detection of fission materials. 相似文献
89.
Yuliya V. Rassukana Ludmyla V. Bezgubenko Oleg V. Stanko Eduard B. Rusanov Irina B. Kulik Petro P. Onysko 《Tetrahedron: Asymmetry》2017,28(4):555-560
The cycloaddition reaction of (S)-(α-phenylethylimino)trifluoropropionate with diazomethane leads to a diastereomeric mixture (4.5:1) of 5-trifluoromethyl-1,2,3-triazoline-5-carboxylates. Enantiopure diastereomers were isolated by column chromatography and converted into their respective non-racemic 2-trifluoromethyl-aziridine-2-carboxylates and carboxylic acids. The absolute configuration of newly formed stereogenic centers was determined by XRD analysis. The stereoselective reaction between (S)-N-(α-phenylethyl)trifluoroacetimidoylphosphonate and diazomethane produces a diastereomeric mixture (2.5:1) of 5-trifluoromethyltriazoline-5-phosphonates readily separated by column chromatography in diastereomerically pure forms. 相似文献
90.
Yu. H. Avetisyan A. H. Makaryan K. Kh. Khachatryan V. R. Tadevosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(3):121-124
We present results of experimental studies of Cherenkov-type generation of a terahertz (THz)-pulse during propagation of a femtosecond laser pulse in LiNbO3 crystal with a Si-prism output coupler. Application of the Si-prism allows reducing essentially the damping of THz radiation because of shortening of the path of THz pulse in the nonlinear crystal. Results of experimental studies agree sufficiently well with theoretical calculations. 相似文献