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91.
92.
María Yolanda Ríos M. Ángeles Ramírez‐Cisneros Ismael León‐Rivera Samuel Estrada‐Soto Gabriel Navarrete‐Vázquez A. Berenice Aguilar‐Guadarrama 《Magnetic resonance in chemistry : MRC》2012,50(4):329-331
Complete 1H and 13C NMR chemical shift assignments for 3,4‐seco‐lup‐20(29)‐en‐3‐oic acid ( 1 ) have been established by means of two‐dimensional COSY, HSQC, HMBC and NOESY spectroscopic experiments as well as by analysis of MS data. Compound 1 was isolated from Decatropis bicolor (Zucc.) Radlk. (Rutaceae) in addition to six coumarins and one alkaloid of known structure. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
93.
Dendronized Anionic Gold Nanoparticles: Synthesis,Characterization, and Antiviral Activity 下载免费PDF全文
Cornelia E. Peña‐González Pilar García‐Broncano Prof. M. Francesca Ottaviani Dr. Michela Cangiotti Dr. Alberto Fattori Margarita Hierro‐Oliva Prof. M. Luisa González‐Martín Dr. Jorge Pérez‐Serrano Dr. Rafael Gómez Prof. M. Ángeles Muñoz‐Fernández Dr. Javier Sánchez‐Nieves Dr. F. Javier de la Mata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2987-2999
Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water‐soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place‐exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X‐ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta‐potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV‐1 infection was higher in the case of dendronized AuNPs than in dendrons. 相似文献
94.
Efrén Andablo-Reyes Roque Hidalgo-Álvarez Juan de Vicente 《ournal of non Newtonian Fluid Mechanics》2010,165(19-20):1419-1421
This communication describes a general procedure for the estimation of the true gap and tilt angle in commercially available torsional flow plate–plate rheometers by simply measuring the torque and normal force acting on the plates when shearing a Newtonian fluid. 相似文献
95.
Arturo Álvarez Vázquez 《Archiv der Mathematik》2010,95(1):25-29
In this paper we present a calculation to study a relationship between the generalized theta function and the Deuring polynomial. 相似文献
96.
Flavonoid glycosides from Persea caerulea. Unraveling their interactions with SDS‐micelles through matrix‐assisted DOSY,PGSE, mass spectrometry,and NOESY 下载免费PDF全文
Juan M. Álvarez Álvaro Raya‐Barón Pedro M. Nieto Luis E. Cuca Alberto Fernández‐Gutiérrez Ignacio Fernández 《Magnetic resonance in chemistry : MRC》2016,54(9):718-728
Two flavonoid glycosides derived from rhamnopyranoside ( 1 ) and arabinofuranoside ( 2 ) have been isolated from leaves of Persea caerulea for the first time. The structures of 1 and 2 have been established by 1H NMR, 13C NMR, and IR spectroscopy, together with LC–ESI–TOF and LC–ESI–IT MS spectrometry. From the MS and MS/MS data, the molecular weights of the intact molecules as well as those of quercetin and kaempferol together with their sugar moieties were deduced. The NMR data provided information on the identity of the compounds, as well as the α and β configurations and the position of the glycosides on quercetin and kaempferol. We have also explored the application of sodium dodecyl sulfate (SDS) normal micelles in binary aqueous solution, at a range of concentrations, to the diffusion resolution of these two glycosides, by the application of matrix‐assisted diffusion ordered spectroscopy (DOSY) and pulse field gradient spin echo (PGSE) methodologies, showing that SDS micelles offer a significant resolution which can, in part, be rationalized in terms of differing degrees of hydrophobicity, amphiphilicity, and steric effects. In addition, intra‐residue and inter‐residue proton–proton distances using nuclear Overhauser effect build‐up curves were used to elucidate the conformational preferences of these two flavonoid glycosides when interacting with the micelles. By the combination of both diffusion and nuclear Overhauser spectroscopy techniques, the average location site of kaempferol and quercetin glycosides has been postulated, with the former exhibiting a clear insertion into the interior of the SDS‐micelle, whereas the latter is placed closer to the surface. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
97.
Emőke-Ágnes Horvát Ferenc Járai-Szabó Yves Brechet Zoltán Néda 《Central European Journal of Physics》2012,10(4):926-935
Fracture patterns resulting from point-like impact acting perpendicularly on the plane of a commercial sodalime glass plate is modelled by a spring-block system. The characteristic patterns consist of crack lines that are spreading radially from the impact point and concentric arcs intersecting these radial lines. Experimental results suggest that the number of radial crack lines is scaling linearly with the energy dissipated during the crack formation process. The elaborated spring-block model reproduces with success the observed fracture patterns and scaling law. 相似文献
98.
Catalytic Activity of Cationic and Neutral Silver(I)–XPhos Complexes with Nitrogen Ligands or Tolylsulfonate for Mannich and Aza‐Diels–Alder Coupling Reactions 下载免费PDF全文
Dr. Abdessamad Grirrane Dr. Eleuterio Álvarez Prof. Dr. Hermenegildo García Prof. Dr. Avelino Corma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):340-354
Cationic and neutral silver(I)–L complexes (L=Buchwald‐type biaryl phosphanes) with nitrogen co‐ligands or organosulfonate counter ions have been synthesised and characterised through their structural and spectroscopic properties. At room temperature, both cationic and neutral silver(I)–L complexes are extremely active catalysts in the promotion of the single and double A3 coupling of terminal (di)alkynes, pyrrolidine and formaldehyde. In addition, the aza‐Diels–Alder two‐ and three‐component coupling reactions of Danishefsky’s diene with an imine or amine and aldehyde are efficiently catalysed by these cationic or neutral silver(I)–L complexes. The solvent influences the catalytic performance due to limited complex solubility or solvent decomposition and reactivity. The isolation of new silver(I)–L complexes with reagents as ligands lends support to mechanistic proposals for such catalytic processes. The activity, stability and metal–distal arene interaction of these silver(I)–L catalysts have been compared with those of analogous cationic gold(I) and copper(I) complexes. 相似文献
99.
Á Császár 《Acta Mathematica Hungarica》2002,95(1-2):83-99
We study properties of the operation
, defined for structures corresponding to different subcategories of MER, as merotopies, filter merotopies, contiguities,
-contiguities and closures. In particular, we examine commutativity of
and the operation according to which a structure induces a structure of another type (as e.g.\ a merotopy induces a closure) and the inverse operations of the former. 相似文献
100.
Ákos Seress 《Acta Appl Math》1998,52(1-3):183-207
We survey polynomial time algorithms (both deterministic and random) for computations with permutation groups. Particular emphasis is given to algorithms with running time of the form O(n log c |G|), where G is a permutation group of degree n. In the case of small-base groups, i.e., when log |G| is polylogarithmic as a function of n, such algorithms run in nearly linear, O(n logc' n) time. Important classes of groups, including all permutation representations of simple groups except the alternating ones, as well as most primitive groups, belong to this category. For large n, the majority of practical computations is carried out on small-base groups.In the last section, we present some new nearly linear time algorithms, culminating in the computation of the upper central series in nilpotent groups. 相似文献