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121.
AymanA. Abdel‐Shafi PaulD. Beer RogerJ. Mortimer Francis Wilkinson 《Helvetica chimica acta》2001,84(9):2784-2795
Photophysical properties in dilute MeCN solution are reported for seven RuII complexes containing two 2,2′‐bipyridine (bpy) ligands and different third ligands, six of which contain a variety of 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridines, for one complex containing no 2,2′‐bipyridine, but 2 of these different ligands, for three multinuclear RuII complexes containing 2 or 4 [Ru(bpy)2] moieties and also coordinated via 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridine ligands, and for the complex [(Ru(bpy)2(L)]2+ where L is N,N′‐([2,2′‐bipyridine]‐4,4′‐diyl)bis[3‐methoxypropanamide]. Absorption maxima are red‐shifted with respect to [Ru(bpy)3]2+, as are phosphorescence maxima which vary from 622 to 656 nm. The lifetimes of the lowest excited triplet metal‐to‐ligand charge transfer states 3MLCT in de‐aerated MeCN are equal to or longer than for [Ru(bpy)3]2+ and vary considerably, i.e., from 0.86 to 1.71 μs. Rate constants kq for quenching by O2 of the 3MLCT states were measured and found to be well below diffusion‐controlled, ranging from 1.2 to 2.0⋅109 dm3 mol−1 s−1. The efficiencies f of singlet‐oxygen formation during oxygen quenching of these 3MLCT states are relatively high, namely 0.53 – 0.89. The product of kq and f gives the net rate constant k for quenching due to energy transfer to produce singlet oxygen, and kq−k equals k, the net rate constant for quenching due to energy dissipation of the excited 3MLCT states without energy transfer. The quenching rate constants were both found to correlate with ΔGCT, the free‐energy change for charge transfer from the excited Ru complex to oxygen, and the relative and absolute values of these rate constants are discussed. 相似文献
122.
Me2Sn(O2PPh2)2 ( 1 ), Ph2Pb(O2PMe2)2 ( 2 ), and Ph2Pb(O2PPh2)2 ( 3 ) have been synthesized by the reactions of Me2SnCl2 or Ph3PbCl with the corresponding diorganophosphinic acid in methanol. X‐ray diffraction studies show that the diorganophosphinate groups behave as double bridges between the metal atoms leading to polymeric ring‐chain structures with M2O4P2 (M = Pb, Sn) eight‐membered rings. The organic groups bonded to the metal atoms are in trans‐position in the resulting octahedral arrangement around the metal atoms. The IR and the mass spectra were reported and discussed. 相似文献
123.
In this work, an approach for finding the solution of coupled semi‐linear diffusion equations for initial value problems is presented. The formal exact solution is found and the Picard iteration is constructed. It is shown that the constructed sequence of solutions converges uniformly for some classes of initial value problems. The problem of dispersion of an oxygen demanding pollutant released into a uniform flow is studied. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
124.
Abdel‐Aziz S. El‐Ahl 《Heteroatom Chemistry》2002,13(4):324-329
Regio‐ and stereospecific syntheses of several spiro[pyrrolidine2,3′‐oxindole] derivatives by cycloaddition trapping of azomethine ylides generated in situ, via decarboxylative condensation of isatin with α‐amino acids or by reaction of secondary amines with isatin, are reported. 2,6‐Dibenzylidenecyclohexanone, 2‐arylidene‐1‐tetralone, and arylidenemalononitrile derivatives have been efficiently used as trapping dipolarophiles. The regio‐ and stereochemistry of the additions are controlled by both frontier orbital and steric interactions. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:324–329, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10038 相似文献
125.
Roumaissa Zenzen Idir Belaidi Samir Khatir Magd Abdel Wahab 《Comptes Rendus Mecanique》2018,346(12):1253-1266
In this paper, a Structural Health Monitoring (SHM) technique for damage identification in beam-like and truss structures using Frequency Response Function (FRF) data coupled with optimization techniques is presented. Genetic Algorithm (GA) and Bat Algorithm (BA) are used to estimate the location and severity of damage. The damage in the structures is simulated by reduction in rigidity of specific members. Both optimization techniques are coupled with modelled structures using Finite Element Method (FEM). The approach is based on minimizing an objective function by comparing measured and calculated FRFs. The results show that better accuracy is obtained using BA than using GA in terms of precision and computational time. Furthermore, it is found that the proposed approach provides faster solution than other approaches in the literature. 相似文献
126.
A. E. Abdel Ghany A. M. A. Hashem H. A. M. Abuzeid A. E. Eid H. A. Bayoumi C. M. Julien 《Ionics》2009,15(1):49-59
Single phase LiCo1 − y
Ni
y
O2 (y = 0.4 and 0.5) with fine particles and high homogeneity was synthesized by “chimie douce” assisted by citric acid as the
polymeric agent and investigated as positive electrodes in rechargeable lithium batteries. The long-range and short-range
structural properties are investigated with experiments including X-ray diffraction (XRD), Fourier transform infrared spectroscopy
(FTIR), and superconducting quantum interference device magnetometry. The physicochemical properties of the powders (crystallinity,
lattice constants, grain size) have been investigated in this composition. The powders adopted the α-NaFeO2 structure as it appeared from XRD and FTIR results. Magnetic measurements shows signal at low temperature attributed to the
magnetic domains in the nanostructure sample from which we estimated that the cation mixing are 3.35 and 4.74% for y = 0.4 and 0.5 in LiCo1 − y
Ni
y
O2, respectively. LiCo0.5Ni0.5O2 cathode yields capacity (135 mAh g−1) compared to LiCo0.6Ni0.4O2 cathode (147 mAh g−1) when discharged to a cutoff voltage of 2.9 V vs. Li/Li+. Lower capacity loss and higher discharge efficiency percentage are observed for the cell of LiCo0.6Ni0.4O2 cathode. 相似文献
127.
Abdel Monem M. Rawashdeh Musa I. El-Barghouthi Khaleel I. Assaf Samer I. Al-Gharabli 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(3-4):357-365
In this work, molecular dynamics (MD) simulations have been conducted to study the inclusion complexes between cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD) with N-methyl-4-(p-methyl benzoyl)-pyridinium methyl cation, and N-methyl-4-(p-methyl benzoyl)-pyridine in aqueous solutions to gain detailed information about the dynamics and mechanism of the inclusion complexes. The obtained MD trajectories were used to estimate the binding free energy of the studied complexes using the molecular mechanics/Poisson Bolzmann surface area (MM–PBSA) method. Results indicate preference of CB7 to bind to the cationic guest more than the neutral guest, whereas β-CD exhibits more or less the same affinity to complex with either species. Furthermore it was interesting to note that β-CD forms more stable complexes with both guests than CB7. Average structure of each complex and the distances between the center of masses of the guest and the host were also discussed. 相似文献
128.
129.
Ramadan M. Abdel‐Motaleb Abdel‐Moneim A. Makhloof Hamada M. Ibrahim Mohamed H. Elnagdi 《Journal of heterocyclic chemistry》2006,43(4):931-934
3‐Amino‐3‐phenyl‐2‐phenylazoacrylonitrile 6 is obtained in good yield via reaction of 5 with phenyl magnesium bromide. The compound 6 is readily converted into 4a . The so formed alkanenitrile reacted with phenylmagnesium bromide to yield 8 . Compound 8 could be also obtained from reaction of 9 with phenylmagnesium bromide. The arylhydrazononitriles 8 and 4a reacted with chloroacetonitrile to yield the 4‐aminopyrazoles 12a,b . Compound 12a reacted with acetic anhydride to yield the 15a and with benzoyl chloride to yield the pyrazole 16 which was converted into 15b . Refluxing 10 in acetic acid gave a mixture of the azadiene 21 and the cinnoline 22 is obtained. The azadiene 21 is converted into 22 either thermally or photochemically. 相似文献
130.
Generic axiomatic-nonextensive statistics introduces two asymptotic properties,to each of which a scaling function is assigned.The first and second scaling properties are characterized by the exponents c and d,respectively.In the thermodynamic limit,a grand-canonical ensemble can be formulated.The thermodynamic properties of a relativistic ideal gas of hadron resonances are studied,analytically.It is found that this generic statistics satisfies the requirements of the equilibrium thermodynamics.Essential aspects of the thermodynamic self-consistency are clarified.Analytical expressions are proposed for the statistical fits of various transverse momentum distributions measured in most-central collisions at different collision energies and colliding systems.Estimations for the freezeout temperature(T_(ch)) and the baryon chemical potential(μ_b) and the exponents c and d are determined.The earlier are found compatible with the parameters deduced from Boltzmann-Gibbs(BG) statistics(extensive),while the latter refer to generic nonextensivities.The resulting equivalence class(c,d) is associated with stretched exponentials,where Lambert function reaches its asymptotic stability.In some measurements,the resulting nonextensive entropy is linearly composed on extensive entropies.Apart from power-scaling,the particle ratios and yields are excellent quantities to highlighting whether the particle production takes place(non)extensively.Various particle ratios and yields measured by the STAR experiment in central collisions at 200,62.4 and 7.7 GeV are fitted with this novel approach.We found that both c and d 1,i.e.referring to neither BG-nor Tsallis-type statistics,but to(c,d)-entropy,where Lambert functions exponentially rise.The freezeout temperature and baryon chemical potential are found comparable with the ones deduced from BG statistics(extensive).We conclude that the particle production at STAR energies is likely a nonextensive process but not necessarily BG or Tsallis type. 相似文献