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91.
Inside Back Cover: Alkaline Earth Metal Zirconate Perovskites MZrO3 (M=Ba2+, Sr2+, Ca2+) Derived from Molecular Precursors and Doped with Eu3+ Ions (Chem. Eur. J. 14/2016) 下载免费PDF全文
92.
Agnieszka Tomaszewska Grzegorz Moskal Damian Migas Marta Mikuśkiewicz Tomasz Maciąg 《Journal of Thermal Analysis and Calorimetry》2018,134(1):157-164
The γ–γ′ Co-based superalloys are newly developed class of refractory alloys which may replace commercial Ni-based superalloys owing to their favorable properties at high temperature. In case of new Co-based superalloys, the heat treatment aims to obtain microstructure composed of appropriate volume fraction of small cuboidal γ′-Co3(Al,W) precipitates within the γ-Co matrix. However, due to a high tendency to interdendritic segregations of alloying elements, the alloys based on Co–Al–W system should be normally homogenized before further steps of heat treatment (solutionizing and aging). In this study, thermal analysis was applied for determination of temperature range for primary heat treatment of the Co–9Al–9W (at.%). The differential thermal analysis (DTA) measurements were carried out on the thermal analyzer NETZSCH STA 449 F3 Jupiter. On the base of obtained results, respectively, solvus of γ′ phase and solidus temperatures were determined, as well as the thermal range of Co3W (DO19) phase precipitation. As a consequence, the heat treatment without homogenizing (only solution and aging) was proposed as a most suitable way to obtain beneficial microstructure. 相似文献
93.
94.
Róg T Stimson LM Pasenkiewicz-Gierula M Vattulainen I Karttunen M 《The journal of physical chemistry. B》2008,112(7):1946-1952
The 3alpha-hydroxyl group is a characteristic structural element of all membrane sterol molecules, while the 3-ketone group is more typically found in steroid hormones. In this work, we investigate the effect of substituting the hydroxyl group in cholesterol with the ketone group to produce ketosterone. Extensive atomistic molecular dynamics simulations of saturated lipid membranes with either cholesterol or ketosterone show that, like cholesterol, ketosterone increases membrane order and induces condensation. However, the effect of ketosterone on membrane properties is considerably weaker than that of cholesterol. This is largely due to the unstable positioning of ketosterone at the membrane-water interface, which gives rise to a small but significant number of flip-flop transitions, where ketosterone is exchanged between membrane leaflets. This is remarkable, as flip-flop motions of sterol molecules have not been previously reported in analogous lipid bilayer simulations. In the same context, ketosterone is found to be more tilted with respect to the membrane normal than cholesterol. The atomic level mechanism responsible for the increase of the steroid tilt and the promotion of flip-flops is the decrease in polar interactions at the membrane-water interface. Interactions between lipids or water and the ketone group are found to be weaker than in the case of the hydroxyl group, which allows ketosterone to penetrate through the hydrocarbon region of a membrane. 相似文献
95.
Lie M Barnholt Klepper K Nilsen O Fjellvåg H Kjekshus A 《Dalton transactions (Cambridge, England : 2003)》2008,(2):253-259
Thin films of iron cobalt oxides with spinel-type structure are made by the atomic layer deposition (ALD) technique using Fe(thd)3 (Hthd = 2,2,6,6-tetramethylheptane-3,5-dione), Co(thd)2, and ozone as precursors. Pulse parameters for ALD-type growth are established and such growth can be achieved at deposition temperatures between 185 and 310 degrees C. Films have been deposited on amorphous soda-lime glass and single-crystalline substrates of Si(100), MgO(100), and alpha-Al2O3(001) which all provide crystalline films, but with various orientations and crystallite sizes. Application of an external magnetic field during the film growth does not influence film growth characteristics (growth rate, crystallinity, topography etc.). Magnetization data are reported for phase-pure films of spinel-type structure with composition Fe2CoO4. 相似文献
96.
Sarac OS Gürsoy-Yüzügüllü O Cetin-Atalay R Atalay V 《Computational Biology and Chemistry》2008,32(2):122-130
Automated classification of proteins is indispensable for further in vivo investigation of excessive number of unknown sequences generated by large scale molecular biology techniques. This study describes a discriminative system based on feature space mapping, called subsequence profile map (SPMap) for functional classification of protein sequences. SPMap takes into account the information coming from the subsequences of a protein. A group of protein sequences that belong to the same level of classification is decomposed into fixed-length subsequences and they are clustered to obtain a representative feature space mapping. Mapping is defined as the distribution of the subsequences of a protein sequence over these clusters. The resulting feature space representation is used to train discriminative classifiers for functional families. The aim of this approach is to incorporate information coming from important subregions that are conserved over a family of proteins while avoiding the difficult task of explicit motif identification. The performance of the method was assessed through tests on various protein classification tasks. Our results showed that SPMap is capable of high accuracy classification in most of these tasks. Furthermore SPMap is fast and scalable enough to handle large datasets. 相似文献
97.
Amine functionalised metal organic frameworks (MOFs) as adsorbents for carbon dioxide 总被引:1,自引:0,他引:1
Bjørnar Arstad Helmer Fjellvåg Kjell Ove Kongshaug Ole Swang Richard Blom 《Adsorption》2008,14(6):755-762
Three different porous metal organic framework (MOF) materials have been prepared with and without uncoordinated amine functionalities
inside the pores. The materials have been characterized and tested as adsorbents for carbon dioxide. At 298 K the materials
adsorb significant amount of carbon dioxide, the amine functionalised adsorbents having the highest CO2 adsorption capacities, the best adsorbing around 14 wt% CO2 at 1.0 atm CO2 pressure. At 25 atm CO2 pressure, up to 60 wt% CO2 can be adsorbed. At high pressures the CO2 uptake is mostly dependent on the available surface area and pore volume of the material in question. For one of the iso-structural
MOF pairs the introduction of amine functionality increases the differential adsorption enthalpy (from isosteric method) from
30 to around 50 kJ/mole at low CO2 pressures, while the adsorption enthalpies reach the same level at increase pressures. The high pressure experimental results
indicate that MOF based solid adsorbents can have a potential for use in pressure swing adsorption of carbon dioxide at elevated
pressures. 相似文献
98.
Density functional theory calculations within the generalized-gradient approximation are used to establish the ground-state structure, equilibrium structural parameters, and electronic structure for MBeH(3) phases. From the 24 structural arrangements used as inputs for structural optimization calculations, the ground-state crystal structures of MBeH(3) phases have been predicted. At ambient conditions, LiBeH(3) and NaBeH(3) crystallize with perovskite-related orthorhombic and cubic structures, respectively. The remaining phases KBeH(3), RbBeH(3), and CsBeH(3) crystalize in a monoclinic structure. In the predicted phases one can store up to 15.93 wt % of hydrogen. The formation energy for the MBeH(3) phases have been investigated along different reaction pathways. The electronic structures reveal that all these phases are insulators with estimated band gaps varying between 1.79 and 3.44 eV. 相似文献
99.
A numerical investigation is performed addressing the optimal design of stiff structures accounting for uncertainty in loading amplitudes. A minimum volume problem is endowed with a stochastic compliance constraint handling normal distributions and solved adopting mathematical programming. The formulation, originally conceived for a single load case, is extended to handle multiple load cases. Numerical simulations are performed to test the proposed algorithms, pointing out features of the numerical procedures and peculiarities of the stochastic-based optimal solutions achieved for different values of the second-order moments. Comparisons with respect to conventional deterministic layouts are provided as well. 相似文献
100.
Ahmet Colak Ender Cekirge Serdar Karaböcek Aslıgül Küçükdumlu Nagihan Sağlam Ertunga Melek Col Rza Abbasoğlu 《Chemical Papers》2009,63(5):554-561
Nucleolytic activities of some new oxime-type ligand complexes were investigated by neutral agarose gel electrophoresis. Analysis
of the cleavage products in agarose gel indicated that all complexes used converted supercoiled pUC18 plasmid DNA to its nicked
or linear form. It was found that nucleolytic activities of the complexes depend on the complex concentration, reaction time
and the presence of a cooxidant (magnesium monoperoxyphthalate, MMPP) in the reaction mixture. However, the complexes cleaved
pUC18 plasmid DNA at all investigated pH values. Nucleolytic activities of complexes were investigated for different complex
concentrations (0.1–100 μmol L−1), pH values (6.0–10.0) and reaction times (0–60 min). Molecular modeling studies performed by the Hyperchem Software together
with DNA-binding studies showed that planar sites of the complexes intercalated into double stranded DNA. It can be concluded
that all oxime-type ligand complexes used can be evaluated as nuclease mimics. 相似文献