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151.
Svetlana M. Stanišić Ljubiša M. Ignjatović Dragan D. Manojlović Biljana P. Dojčinović 《Central European Journal of Chemistry》2011,9(3):481-491
This paper presents the extraction of cations from a soil sample, type ranker on serpentinite, in deionized water, by use
of three different extraction techniques. The first extraction technique included the use of a rotary mixer, the second technique
involved the use of a microwave digestion system with different extraction temperatures, and the third technique employed
an ultrasonic bath with different extraction times. Ion chromatography was used for determining the concentration of Li, Na,
K, Ca, Mg and ammonium ions in soil extracts with subsequent determination of concentrations for all cations, except for ammonium
ion extraction, conducted by Inductively Coupled Plasma-Atomic Emission Spectrometry. The results of cation extractions showed
that microwave assisted extraction was most efficient for the Li, Na, K, Ca, Mg, Co, Mn, Ni, Pb and ammonium ions. Use of
a rotary mixer for extraction was most efficient for Cd and Zn ions, while use of ultrasound bath was most efficient for Cr,
Cu, Fe and Al ions. Several times higher amount of cations extracted by the most efficient, compared to the second best technique,
under optimal conditions, were noticed in the case of: Ca, Mg, Co, Mn, Fe, Al, and Zn ions. 相似文献
152.
153.
Quantum Ising models in a transverse field are related to continuous-time percolation processes whose oriented percolation versions are contact processes. We study such models in the presence of quasiperiodic disorder and prove localization in the ground state, no percolation, and extinction, respectively, for sufficiently large disorder. 相似文献
154.
155.
Svetlana A. Kravchenko Yuri N. Sotskov 《Mathematical Methods of Operations Research》1996,43(2):233-238
This paper deals with the problem of scheduling three jobs on two machines in order to minimize the makespan, when operation
preemptions are forbidden and routes are fixed and may vary per job. It is shown that this problem can be solved by anO(r
4) algorithm, wherer is the maximal number of operations per job.
Supported by Belarussian Fundamental Research Found, Project Φ60–242, and Deutsche Forschungsgemeinschaft, Project ScheMA 相似文献
156.
Shvedene NV Borovskaya SV Sviridov VV Ismailova ER Pletnev IV 《Analytical and bioanalytical chemistry》2005,381(2):427-430
Polyvinyl chloride-plasticized membrane ion-selective electrodes (ISE) based on conventional ion-exchangers have been proposed as a cheap universal tool to measure the solubilities of ionic liquids (ILs) in water. They are applicable for ILs with a wide range of solubilities in water, since the linear range of a potentiometric response spans several orders of magnitude. As an example, we have fabricated and tested ISEs for widely used alkylimidazolium ionic liquids. The aqueous solubilities of four typical ILs have been determined at 21 °C: 0.075±0.001 mol l–1 (1-butyl-3-methylimidazolium, BMIm, hexafluorophosphate); 0.018±0.001 mol l–1 (BMIm bis(triflylimide)); 0.054±0.007 mol l–1 (1-butyl-2,3-dimethylimidazolium, BDMIm, hexafluorophosphate); 0.014±0.001 mol l–1 (BDMIm bis(triflylimide)). 相似文献
157.
Anton A. Kolesnikov Yurii E. Lozovik Svetlana P. Merkulova 《Journal of Russian Laser Research》2010,31(5):469-474
We propose a new method of laser spectroscopy, which combines high subwavelength space resolution, high sensitivity, and spectral resolution. The method is based on using a fiber laser near the generation threshold instead of a fiber optical near-field microscope. The near-field subwavelength aperture in the “active” fiber is employed for probing. Absorption on the objects under consideration (atoms, molecules, nanostructure, etc.) leads to the failure of oscillations in the fiber laser. We make a computer simulation of the system under consideration and analyze the method’s sensitivity. 相似文献
158.
Pavlova SV To HL Chan ES Li HW Mak TC Lee HK Chan SI 《Dalton transactions (Cambridge, England : 2003)》2006,(18):2232-2243
The air-sensitive bis(micro-iodo)dicopper(I) complex 1 supported by [N-(3,5-di-tert-butyl-2-hydroxybenzyl)-N,N-di-(2-pyridylmethyl)]amine (L) has been prepared by treating copper(I) iodide with L in anhydrous THF. Compound 1 crystallizes as a dimer in space group C2/c. Each copper(I) center has distorted tetrahedral N2I2 coordination geometry with Cu-N(pyridyl) distances 2.061(3) and 2.063(3) A, Cu-I distances 2.6162(5) and 2.7817(5) and a Cu...Cu distance of 2.9086(8) A. Complex 1 is rapidly oxidized by dioxygen in CH2Cl2 with a 1 : 1 stoichiometry giving the bis(micro-iodo)peroxodicopper(II) complex [Cu(L)(micro-I)]2O2 (2). The reaction of 1 with dioxygen has been characterized by UV-vis, mass spectrometry, EPR and Cu K-edge X-ray absorption spectroscopy at low temperature (193 K) and above. The mass spectrometry and low temperature EPR measurements suggested an equilibrium between the bis(micro-iodo)peroxodicopper(II) complex 2 and its dimer, namely, the tetranuclear (peroxodicopper(II))2 complex [Cu(L)(micro-I)]4O4 (2'). Complex 2 undergoes an effective oxo-transfer reaction converting PPh3 into O=PPh3 under anaerobic conditions. At sufficiently high concentration of PPh3, the oxygen atom transfer from 2 to PPh3 was followed by the formation of [Cu(PPh3)3I]. The dioxygen reactivity of 1 was compared with that known for other halo(amine)copper(I) dimers. 相似文献
159.
Chebanov VA Muravyova EA Desenko SM Musatov VI Knyazeva IV Shishkina SV Shishkin OV Kappe CO 《Journal of combinatorial chemistry》2006,8(3):427-434
Multicomponent reactions (MCRs) and microwave-assisted organic synthesis (MAOS) have been used as key methods for the synthesis of fused dihydropyrimidine derivatives. The three-component condensation of 3-amino-5-alkylthio-1,2,4-triazoles with aromatic aldehydes and acetoacetamides under microwave irradiation was developed as a rapid and efficient solution-phase method for the high-yielding preparation of 7-aryl-2-alkylthio-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxamide libraries. In addition, the selective reduction of the formed dihydrotriazolopyrimidines to trans-trans-2-alkylthio-7-aryl-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidine-6-carboxamides was established. The described synthetic protocols provide rapid access to novel and diversely substituted dihydroazolopyrimidine libraries. 相似文献
160.