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891.
Yahong Li Pengsheng Song Wu Li Shuping Xia 《Russian Journal of Inorganic Chemistry》2008,53(12):1967-1971
The component solubilities of the HCl-MgCl2-H2O system at −5°C were predicted by using the Pitzer ion interaction model and its extended Harvie and Weare model. The results
indicated that the model supplies a good prediction of the above-mentioned system. The values of parameters of β(0), β(1), and C
φ of HCl and MgCl2 were obtained by using the same optimization methods as in the literature, while those of θMgH and ΨMgHCl were derived by extrapolating the published data of 5, 15, 25, 35, and 45°C, as well as coupling the activity coefficients
with the solubility data. The comparison between the calculated results and the experimental data indicated that the Pitzer
ion interaction model and its extended Harvie and Weare model are quite reliable in the solubility prediction.
The text was submitted by the authors in English 相似文献
892.
A New Approach for Titration Calorimetric Data Analysis on the Binding of Magnesium Ion with Myelin Basic Protein 总被引:1,自引:0,他引:1
G. Rezaei Behbehani A. A. Saboury A. Fallah Baghery 《Journal of solution chemistry》2008,37(8):1127-1135
The interaction of the myelin basic protein (MBP) from the bovine central nervous system with divalent magnesium ion was studied
by isothermal titration calorimetry at 27 °C in aqueous solution. A simple rapid method for determination of the dissociation
binding constants for Mg2+-MBP interaction was introduced using the isothermal titration calometric data. The binding isotherm for Mg2+-MBP interaction is easily obtained by carrying out a titration calorimetric experiment using only one set of concentrations
of MBP. There are two identical independent intrinsic association constants equal to 0.021 μmol⋅L−1 in the first- and second-binding sites, respectively. 相似文献
893.
We introduce PULCHRA, a fast and robust method for the reconstruction of full-atom protein models starting from a reduced protein representation. The algorithm is particularly suitable as an intermediate step between coarse-grained model-based structure prediction and applications requiring an all-atom structure, such as molecular dynamics, protein-ligand docking, structure-based function prediction, or assessment of quality of the predicted structure. The accuracy of the method was tested on a set of high-resolution crystallographic structures as well as on a set of low-resolution protein decoys generated by a protein structure prediction algorithm TASSER. The method is implemented as a standalone program that is available for download from http://cssb.biology.gatech.edu/skolnick/files/PULCHRA. 相似文献
894.
The lipophilicity of the series of alpha-(4-phenylpiperazin-1-yl)-gamma-phthalimido-butyramides (1-8) has been investigated. Several methods, like reversed-phase thin-layer chromatography and high-performance liquid chromatography using reversed-phase RP18 and IAM.DD2 columns, were applied to determine RMO, log k0 and log k(0IAM) factors. The RP-TLC investigations were performed in mixtures of acetone-water and acetonitrile-water. For RP-HPLC method mixtures of acetonitrile, water and 0.01% TFA were used as the mobile phases while for IAM.DD2 investigations mixtures of acetonitrile and water were applied. The partition coefficients of compounds (1-8) were also calculated with the Pallas and CAChe programs. All the obtained data, both from experimental methods and computational calculations, were compared and a suitable conclusion was reached. 相似文献
895.
Abdoul-Fatah Kanta Ghislain Montavon Marie-Pierre Planche Christian Coddet 《Plasma Chemistry and Plasma Processing》2008,28(2):249-262
Modeling the behavior of air plasma spray (APS) process, one of the challenges nowadays is to identify the parameter interdependencies,
correlations and individual effects on coating properties, characteristics and influences on the in-service properties. APS
modeling requires a global approach which considers the relationships between coating characteristics/ in-service properties
and process parameters. Such an approach permits to reduce the development costs. This is why a robust methodology is needed
to study these interrelated effects. Artificial intelligence based on fuzzy logic and artificial neural network concepts offers
the possibility to develop a global approach to predict the coating characteristics so as to reach the required operating
parameters. The model considered coating properties (porosity) and established the relationships with power process parameters
(arc current intensity, total plasma gas flow rate, hydrogen content) on the basis of artificial intelligence rules. Consequently,
the role and the effects of each power process parameter were discriminated. The specific case of the deposition of alumina–titania
(Al2O3–TiO2, 13% by weight) by APS was considered. 相似文献
896.
《印度化学会志》2023,100(1):100860
This study investigates the influence of synthesis processes such as sonication, sol-gel, and microwave on the production of highly crystalline Lanthanum oxide nanoparticles (La2O3) employing Lanthanum nitrate and Ammonium hydroxide (NH4OH) as precursors. X-ray diffraction (XRD), particle size analysis (DLS), Field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV–Vis), and electrochemical impedance spectroscopy (EIS) were used to examine the most effective processing method and its effects on the nanoparticle characteristics, such as structure, morphology, and optical and electrical behavior. Sonication produces La2O3 NPs with a smaller crystalline size, an agglomerated nanorod structure, a higher bandgap, and better electrical responsiveness than sol-gel and microwave techniques. Structural and optical characterization tests discovered this. The photocatalytic degradation activity of cationic Safranin and anionic Congo red dye exhibits degradation efficiency of around 90.13% and 89.66%, respectively. 相似文献
897.
James R. Durig Ahmed M. El Defrawy Rachel M. Ward Gamil A. Guirgis Todor K. Gounev 《Structural chemistry》2008,19(4):579-594
Variable temperature (?55 to ?105 °C) studies of the infrared spectra (4000–400 cm?1) of chlorocyclohexane (c-C6H11Cl) dissolved in liquefied xenon have been carried out. The infrared spectra of the gas and solid have also been recorded from 4000–100 cm?1. By analyzing six conformer pairs in the xenon solution, a standard enthalpy difference of 132 ± 13 cm?1 (1.58 ± 0.16 kJ/mol) was obtained with the equatorial conformer the more stable form. At ambient temperature, the abundance of the axial conformer is 34 ± 1%. The potential surface describing the conformational interchange has been determined and the Fourier coefficients were obtained. From MP2 ab initio calculations utilizing various basis sets with and without diffuse functions, the equatorial conformer is predicted to be more stable by 161 ± 18 cm?1 from the four largest basis set calculations, which is consistent with the experimental results. However, the average from the corresponding B3LYP density functional theory calculations is 274 ± 15 cm?1 which is certainly too large. By utilizing the previously reported microwave rotational constants for two isotopomers (35Cl, 37Cl) combined with the structural parameters predicted from the MP2(full)/6-311+G(d,p) calculations, adjusted r 0 structural parameters have been obtained. The determined heavy atom distances for the most stable chair-equatorial conformer in Å are: r 0(C1–C7,8) = 1.532(3); r 0(C7,8–C13,14) = 1.536(3); r 0(C4–C13,14) = 1.524(3); and r 0(C4–Cl6) = 1.802(5) and the angles in degrees: ∠C1C7,8C13,14 = 111.3(5)º; ∠Cl6C4C13,14 = 109.7(5)º with the two dihedral angles ∠C8C1C7C13 = 56.3(10)º and ∠C14C4C13C7 = 56.7(10)º. These parameters are in good agreement with those reported earlier from microwave and electron diffraction studies where the CC and CH distances were all assumed to be equal. A few of the previously reported vibrational assignments have been corrected. The results of these spectroscopic and theoretical studies are discussed and compared to the corresponding results for some similar molecules. 相似文献
898.
899.
Polyurethane cationomers were synthesised in the reaction of various diisocyanates with polyoxypropylene glycol and two N-alkyldiethanolamines. The obtained isocyanate prepolymers were then extended in the aqueous medium by means of 1,6-hexamethylenediamine;
stable aqueous dispersions were thus obtained, which were applied to and distributed over the poly(tetrafluoroethylene) surface.
After evaporation of water from those dispersions, thin polymer coatings were produced. The analyses with the use of 1H, carbon-13 nuclear magnetic resonance and infrared spectroscopy methods confirmed chemical structures of synthesised cationomers.
Also, attempts were made to quantitatively characterise polarities of those structures by means of factors that were defined
especially for that purpose. Moreover, the physical model of van Oss–Good and wetting angles for coatings obtained from the
polyurethane cationomers in question, measured with the use of standard liquids with various polarity specifications, were
utilised to determine the surface free energy values for the obtained ionomers. 相似文献
900.
A kinetic study is reported for alkaline hydrolysis of X‐substituted phenyl diphenylphosphinates ( 1 a – i ). The Brønsted‐type plot for the reactions of 1 a – i is linear over 4.5 pKa units with βlg=?0.49, a typical βlg value for reactions which proceed through a concerted mechanism. The Hammett plots correlated with σo and σ? constants are linear but exhibit many scattered points, while the corresponding Yukawa–Tsuno plot results in excellent linear correlation with ρ=1.42 and r=0.35. The r value of 0.35 implies that leaving‐group departure is partially advanced at the rate‐determining step (RDS). A stepwise mechanism, in which departure of the leaving group from an addition intermediate occurs in the RDS, is excluded since the incoming HO? ion is much more basic and a poorer nucleofuge than the leaving aryloxide. A dissociative (DN + AN) mechanism is also ruled out on the basis of the small βlg value. As the substituent X in the leaving group changes from H to 4‐NO2 and 3,4‐(NO2)2, ΔH ≠ decreases from 11.3 kcal mol?1 to 9.7 and 8.7 kcal mol?1, respectively, while ΔS ≠ varies from ?22.6 cal mol?1 K?1 to ?21.4 and ?20.2 cal mol?1 K?1, respectively. Analysis of LFERs combined with the activation parameters assigns a concerted mechanism to the current alkaline hydrolysis of 1 a – i . 相似文献