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111.
Mohamed I. Hegab Nasser A. Hassan Emad M. El‐Telbani Ibrahim S. Ahmed Farag Farouk M. E. Abdel‐Megeid 《Heteroatom Chemistry》2003,14(3):223-228
Hydrazones 12a–c and ketazines 13a–c were prepared by the reaction of ketones 11a–c with hydrazine hydrate depending on the temperature and the reaction time. Some ketone (aryl)hydrazone derivatives 14a,c,e reacted with thionyl chloride to afford the chlorothiadiazoline derivatives 15a–c . Surprisingly, the chlorine atom in the latter compounds was found to undergo smooth nucleophilic substitution, and by boiling these compounds in absolute ethanol gave the corresponding ethoxythiadiazoline derivatives 16a–c . The structure of the ethoxythiadiazoline 16b was confirmed by single crystal X‐ray determination. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:223–228, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10125 相似文献
112.
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
113.
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
114.
Nouria A. Al-Awadi Mohamed H. Elnagdi Tommy Mathew Ibrahim El-Gamry Mervat Abdel Khalik 《国际化学动力学杂志》1996,28(10):741-748
Pyrolysis of the Schiff bases of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles (1–5) has been studied. These compounds eliminate via a six-membered transition state to produce substituted benzonitriles and 2-hydroxy-4,6-dimethylpyridine-3-carbonitrile. These eliminations are unimolecular first-order reactions. The kinetic data gave a good correlation with σ0 values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open-chain substituted benzaldehyde cyanoacetylhydrazones (6–9) analogues. © 1996 John Wiley & Sons, Inc. 相似文献
115.
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
116.
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
117.
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
118.
119.
Omar Boussaid Pablo Pedregal 《Calculus of Variations and Partial Differential Equations》2009,34(2):139-152
By a suitable reformulation of a typical optimal design problem in conductivity, we treat the issue of determining the quasiconvexification
(to fixed volume fraction) of certain sets of matrices that are union of two manifolds. By means of a helpful lemma, we are
able to explicitly compute such hulls in a rather straightforward fashion without the need of seeking laminates by hand, and
hence avoiding some tedious computations. We examine the linear case, both elliptic and hyperbolic, in 2 and higher dimension
(by looking at a div–curl situation), as well as an interesting non-linear example that provides some clue as to what kind
of characterization one may hope for in non-linear situations.
This work was supported by the research projects MTM2007-62945 of the MCyT (Spain) and PCI08-0084-0424 of the JCCM (Castilla-La
Mancha). 相似文献
120.
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