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141.
Borstnik U Hodoscek M Janezic D 《Journal of chemical information and computer sciences》2004,44(2):359-364
In this article a procedure is derived to obtain a performance gain for molecular dynamics (MD) simulations on existing parallel clusters. Parallel clusters use a wide array of interconnection technologies to connect multiple processors together, often at different speeds, such as multiple processor computers and networking. It is demonstrated how to configure existing programs for MD simulations to efficiently handle collective communication on parallel clusters with processor interconnections of different speeds. 相似文献
142.
Peter Segl'a Martina Palicov Dusan Miklos Marian Koman Milan Melník Maria Korabik Jerzy Mrozinski Tadeusz Glowiak Markku R. Sundberg Peter Lnnecke 《无机化学与普通化学杂志》2004,630(3):470-478
Synthesis and characterization of seven new complexes [Cu(2‐MeSnic)2(CH3OH)]2 (where 2‐MeSnic is 2‐methylthionicotinate), [Cu(2‐MeSnic)2L2]2 (where L is pyridine — py, ethylnicotinate — Etnic and butylnicotinate — Bunic), [Cu(2‐MeSnic)2L2(H2O)2] (where L is py and nicotinamide — nia) and [Cu(2‐MeSnic)2(N‐Menia)2(H2O)2]·2H2O (where N‐Menia is N‐methylnicotinamide) are reported. The characterization were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic susceptibility measurements over a temperature range of 1.8 — 300 K or 70 — 300 K. Three complexes of different type were studied by X‐ray analysis. The molecule of [Cu(2‐MeSnic)2(CH3OH)]2 has dimeric paddle‐wheel cage structure with a tetragonal pyramidal arrangement around CuII. The dimer results from the fact that carboxyl groups of four 2‐MeSnic anions function as bridging in a syn‐syn arrangement. On the other hand [Cu(2‐MeSnic)2(py)2]2 forms dimers with hexacoordinated CuII atoms in highly distorted coordination octahedra, each with two oxygen atoms of bridging carboxyl groups in an anti‐anti arrangement of two 2‐MeSnic anions, with two oxygen atoms of one asymmetrically chelating 2‐MeSnic anion and with two nitrogen atoms of two pyridine ligands. The temperature independent EPR spectrum for this complex exhibits an axial signal which corresponds to almost isolated S = 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = —0.65 cm—1. The CuII atom in complex [Cu(2‐MeSnic)2(py)2(H2O)2] is hexacoordinated in an elongated centrosymmetrical tetragonal‐bipyramidal arrangement (4 + 2). Based on the molecular structure the electronic, infrared, electron paramagnetic resonance spectra and magnetic properties are discussed and stereochemistry as well as the mode of ligand coordination in new solid complexes under study have been determined. 相似文献
143.
Mira S. Bjelakovi? Natalija M. Krsti? Aleksej Kruni? Milan M. Dabovi? 《Tetrahedron》2009,65(46):9557-9568
In this paper a synthetic pathway to the modified 5,10:13,14-bisfragmentation cholestane derivatives 8-14 is described. The synthesis involves introduction of the 5α- and 14α-hydroxyl groups in the cholestane molecule and subsequent cleavage of the C(5)-C(10) bond in 5α,14α-dihydroxycholestan-3β-yl acetate (4) with the HgO/I2 reagent and the C(13)-C(14) bond in the stereoisomeric 14α-hydroxy-5,10-secosteroids 5 and 6 with the Pb(OAc)4/I2 reagent. Complete and unambiguous 1H and 13C NMR resonance assignments of the obtained secosteroids, as well as the solution conformations of their 10- and 9-membered rings were determined by extensive analysis of 1D and 2D NMR spectral data. The structures and the solid-state conformations of 5,10-secosteroids 5-7 were confirmed by X-ray analysis. All diseco-compounds have a novel 5,10:13,14-disecocholestane skeleton. 相似文献
144.
Július ille Martin ramko Vladimír Garaj Milan Remko 《Journal of Molecular Structure》2009,911(1-3):137-143
The structure and gas-phase metal affinities (M = Cu2+, Ni2+, and Zn2+) of formohydroxamic acid derivatives R–C(O)NHOH (R = H, NH2, CH3, CF3 and Phenyl) were studied using the B3LYP/6-311+G(d,p) method of DFT theory. In order to evaluate the conformational behavior of these systems in water, we carried out CPCM-SCRF optimization calculations at the B3LYP/6-311+G(d,p) levels of theory. The obtained optimized geometries and interaction affinities of the gas and solution phase were compared. The following order of stability was found for ionic complexes of the transition metals: Cu2+ > Ni(t)2+ > Zn2+. The same stability order would be expected according to the Irving–Williams order of stability constants. The high-spin complexes of the Ni2+ were more stable than the low-spin complexes. The solvent effect reduced the observed relative stability of individual metallic complexes of substituted hydroxamic acids. 相似文献
145.
Benoît Lessard Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2009,47(10):2574-2588
Methyl methacrylate/styrene (MMA/S), ethyl methacrylate/styrene (EMA/S) and butyl methacrylate/styrene (BMA/S) feeds (>90 mol % methacrylate) were copolymerized in 50 wt % p‐xylene at 90 °C with 10 mol % of additional SG1‐free nitroxide mediator relative to unimolecular initiator (BlocBuilder®) to yield methacrylate rich copolymers with polydispersities w/ n = 1.23–1.46. kpK values (kp = propagation rate constant, K = equilibrium constant) for MMA/S copolymerizations were comparable with previous literature, whereas EMA/S and BMA/S copolymerizations were characterized by slightly higher kpK's. Chain extensions with styrene at 110 °C initiated by the methacrylate‐rich macroinitiators (number average molecular weight n = 12.9–33.5 kg mol?1) resulted in slightly broader molecular weight distributions with w/ n = 1.24–1.86 and were often bimodal. Chain extensions with glycidyl methacrylate/styrene/methacrylate (GMA/S/XMA where XMA = MMA, EMA or BMA) mixtures at 90 °C using the same macroinitiators resulted frequently in bimodal molecular weight distributions with many inactive macroinitiators and higher w/ n = 2.01–2.48. P(XMA/S) macroinitiators ( n = 4.9–8.9 kg mol?1), polymerized to low conversion and purified to remove “dead” chains, initiated chain extensions with GMA/MMA/S and GMA/EMA/S giving products with w/ n ~ 1.5 and much fewer unreacted macroinitiators (<5%), whereas the GMA/BMA/S chain extension was characterized by slightly more unreacted macroinitiators (~20%). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2574–2588, 2009 相似文献
146.
Zuzana Vasková Jan Moncol Maria Korabik Dušan Valigura Jozef Švorec Tadeusz Lis Marian Valko Milan Melník 《Polyhedron》2010
A new complex of unusual composition [Cu(3-O2Nbz)2(nia)(H2O)2] (1) (nia = nicotinamide, 3-O2Nbz = 3-nitrobenzoate) has been prepared and studied together with two other complexes of composition [Cu(4-O2Nbz)2(nia)2(H2O)2] (2) and [Cu(4-O2Nbz)2(nia)2]?(4-O2NbzH)2 (3) (4-O2Nbz = 4-nitrobenzoate). The composition of all complexes has been determined by elemental analysis, the complexes have been studied by electronic, infrared and EPR spectroscopy, as well as by magnetization measurements over the temperature range 1.8–300 K, and their structures have been solved. The structure of complex (1) consists of molecules, where Cu(II) atom is monodentately coordinated by the pair of 3-nitrobenzoato anions in trans -positions together with water and nicotinamide molecules, forming nearly tetragonal basal plane, and by another water molecule in axial position of tetragonal-pyramidal coordination polyhedron. The neighboring molecule coordination polyhedron basal planes are coplanar and allow formation of supramolecular dimers with strong H-bonds between hydrogen atoms from equatorially coordinated water molecules and uncoordinated carboxylate oxygen atoms thus giving the nearest Cu?Cu distance of 4.886(2) Å. Magnetization measurements showed that complex (1) exhibits maximum of magnetic susceptibility at 6.5 K and a fit to Bleaney-Bowers equation gave singlet–triplet energy gap 2J = −6.25 cm−1, and zJ′ = −0.03 cm−1. This might be an experimental proof that the carboxylate bridges extended with hydrogen bonds are the pathway of the spin–spin interactions. The temperature dependence of changes in EPR spectra of (1) and the spectrum at 4.2 K have confirmed its hydrogen bonded dimeric structure. The calculated Cu?Cu distance 4.8 Å is in very good agreement with the value obtained from crystal structure. The complexes (2) and (3) at 300 K exhibit magnetic moment μeff = 1.98 B.M. and μeff = 1.84 B.M., respectively. These values practically do not change with lowering the temperature up to 5 K and only small drops to μeff = 1.87 B.M. (for (2)) and μeff = 1.79 B.M. (for (3)) at 1.8 K have been observed. The EPR spectra of complex (2) at room temperature as well as at 77 K are of axial type with g⊥ = 2.062 and g|| = 2.285 and exhibit resolved parallel hyperfine splitting with A|| = 160 Gauss. The EPR spectra of complex (3) at room temperature as well as at 77 K are of axial type with g⊥ = 2.065 and g|| = 2.235 and exhibit unresolved parallel hyperfine splitting. EPR spectra of (2) and (3) are consistent with the X-ray structure. 相似文献
147.
A rapid micro‐analytical multiresidue method was developed for analysis of pyrethroids (kadethrin K, cypermethrin C and permethrin P) in soil micro‐sample (200 mg). It uses on‐line flow‐through extraction of soil micro‐samples (packed into a short glass column) with a methanol‐aqueous citric acid buffer mixture, successive on‐line SPE preconcentration of analytes from the extract and on‐line RP‐HPLC analysis with UV photometric detection. The separation of pyrethroids is performed on a Purospher RP‐18e column with methanol/water as mobile phase. Effects of sorbent placed at the bottom of a short column holding the soil sample and different kinds of on‐line SPE columns were tested. Besides, the influence of volume of the effluent on the pyrethroids recovery was also studied. Calibration curves were linear over the range assayed from 0.01 to 0.2 μg/mL with correlation coefficients of linear regression (least‐squares method) in the range 0.998–0.999. Recovery studies were carried out at 0.25–1.00 μg/g dry soil fortification level and obtained recoveries were for K 81–84%, C 56–59% and for P 58–63%. Achieved LOD (confidence band) of studied pyrethroids were for large‐volume injection (1 mL) 4.5 ng K, 3.7 ng C, 3.6 ng P or 27 ng/g K, 32 ng/g C and 29 ng/g P in dry soil “solid sampling HPLC”. 相似文献
148.
149.
Dijana Pei Ivana Ozimec Landek Renata Rup
i Marina Modri Iva Dapo Rudolf Trojko Mladen Merep Milan Mesi 《Journal of heterocyclic chemistry》2012,49(2):243-252
The present review focuses on dibenzo[b,f]oxepin‐10(11H)‐one ( I , X = O) and dibenzo[b,f]thiepin‐10(11H)‐one ( I , X = S) as common synthons in the efficient synthesis of various dibenzoxepino[4,5‐ and dibenzothiepino[4,5]‐fused five‐membered heterocycles: [2,3] fused thiophene ( II ), [3,4] fused thiophene ( III ), furan ( IV ), pyrrole ( V ), imidazole ( VI ), pyrazole ( VII ), oxazole ( VIII ), and thiazole ( IX ). The potential of I to be converted into reactive intermediates that readily undergo heteroaromatic annulation reactions by cyclocondensation with proper binucleophiles allows formation of a range of enumerated functionalized dibenzo[e,h]azulene [4] structures ( II , III , IV , V , VI , VII , VIII , IX ). Dibenzo[e,h]azulenes as heterotetracyclic scaffold can be exploited in further modifications to obtain compounds with altered physicochemical and biological profile. J. Heterocyclic Chem., (2012). 相似文献
150.
Marek Bučko Danica Mislovičová Jozef Nahálka Alica Vikartovská Jana Šefčovičová Jaroslav Katrlík Ján Tkáč Peter Gemeiner Igor Lacík Vladimír Štefuca Milan Polakovič Michal Rosenberg Martin Rebroš Daniela Šmogrovičová Juraj Švitel 《Chemical Papers》2012,66(11):983-998
Biological molecules such as enzymes, cells, antibodies, lectins, peptide aptamers, and cellular components in an immobilized form are extensively used in biotechnology, in biorecognition and in many medicinal applications. This review provides a comprehensive summary of the developments in new immobilization materials, techniques, and their practical applications previously developed by the authors. A detailed overview of several immobilization materials and technologies is given here, including bead cellulose, encapsulation in ionotropic gels and polyelectrolyte complexes, and various immobilization protocols applied onto surfaces. In addition, the review summarises the screening and design of an immobilization protocol, practical applications of immobilized biocatalysts in the industrial production of metabolites, monitoring, and control of fermentation processes, preparation of electrochemical/optical biosensors and biofuel cells. 相似文献