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991.
Philippe Rongère Nicole Morel-Desrosiers Jean-Pierre Morel 《Journal of solution chemistry》1994,23(3):351-362
The thermodynamic characterization of the weakly complexed model system Sm3+-xylitol has been carried out. The standard Gibbs energy enthalpy, entropy, volume and heat capacity of complexation of Sm3+ by xylitol have been determined in water at 25°. The stability constant and the enthalpy change have been simultaneously determined by using a calorimetric method. The thermodynamic properties characterizing solely the specific interaction between the cation and the complexing sequence of hydroxyl groups of the ligand have been isolated. The stability constant and the volume of complexation have also been estimated from a similar treatment of the apparent molar volumes. It was found that the reaction between Sm3+ and the complexing site of xylitol in water is characterized by: K = 8.1, rGo = –5.2 kJ-mol–1, rHo = –13.7 kJ-mol–1, TrSo = –8.5 kJ-mol–1, rVo = 8.8 cm3-mol–1 and rC
p
o
= 51 J-K–1-mol–1. 相似文献
992.
993.
The synthesis of the C1-C11 fragment 33 of bafilomycin A(1) was achieved. Intermediate ketone 16 was prepared in six steps from 4-oxopimelate 13. Desymmetrization of this ketone using Koga's chiral base followed by TMSCl quench furnished silyl enol ether 17 with excellent enantioselectivity. Further elaboration led to C5-C11 aldehyde 24, which was coupled with sulfone 3 to give lactone 25 in very good yield. The subsequent reductive elimination created the E-trisubstituted C4-C5 olefin with a 13:1 selectivity. The E C2-C3 double bond was then installed by methanol elimination, and compound 33 was obtained after a few functional group manipulations and a Negishi methyl zirconation. 相似文献
994.
Christophe Henry K. Karin Norrfors Michał Olejnik Muriel Bouby Johannes Luetzenkirchen Susanna Wold Jean-Pierre Minier 《Adsorption》2016,22(4-6):503-515
This study is focussed on the simulation of particle agglomeration at relatively high ionic strength using a refined stochastic algorithm developed in the context of parcel-tracking approaches. For that purpose, experimental data of both diffusion-limited and reaction-limited aggregation of latex particles were obtained using dynamic light scattering techniques for different initial particle sizes (diameters ranging from 24 to 495 nm) and at various chemical conditions (ionic strength between 0.5 and 2 M with NaCl or CaCl\(_2\) solutions). The experimental data collected have been compared to numerical results obtained with the refined parcel-tracking algorithm for particle agglomeration which has been developed. Results show that the evolution of the aggregate diameters over time can be properly captured by the present model with the value of the aggregate fractal dimension that is extracted from experimental data. 相似文献
995.
996.
Olivier Husson Benoit Husson Alexandre Brunet Daniel Babre Karine Alary Jean-Pierre Sarthou Hubert Charpentier Michel Durand Jaroslav Benada Marc Henry 《Analytica chimica acta》2016
The soil redox potential (Eh) can provide essential information to characterise soil conditions. In practice, however, numerous problems may arise regarding: (i) Eh determination in soils, especially aerobic soils, e.g. variations in the instrumentation and methodology for Eh measurement, high spatial and temporal Eh variability in soils, irreversibility of the redox reaction at the surface electrode, chemical disequilibrium; and (ii) measurement interpretation. 相似文献
997.
Jacques E. Desnoyers Michel Billon Sylvain Léger Gérald Perron Jean-Pierre Morel 《Journal of solution chemistry》1976,5(10):681-691
The freezing-point depression of the ternary systems water-alkali halidesalcohols was measured with a precision Advanced Instrument osmometer. From the corresponding freezing-point depression of the binary systems the salting-out constantsk
s were calculated. The effect of ionic size was investigated withtert-butanol, and the effect of alcohol chain length with NaCl. The trends ofk
s with ionic size are similar to those of typical nonelectrolyte systems, andk
s varies linearly with the volumes of the normal alcohols. 相似文献
998.
999.
Marc Lachièze Rey Jean-Pierre Gazeau Eric Huguet Jacques Renaud Tarik Garidi 《International Journal of Theoretical Physics》2003,42(6):1301-1310
Current views link quantization with dynamics. The reason is that quantum mechanics or quantum field theories address to dynamical systems, i.e., particles or fields. Our point of view here breaks the link between quantization and dynamics: any (classical) physical system can be quantized. Only dynamical systems lead to dynamical quantum theories, which appear to result from the quantization of symplectic structures. 相似文献
1000.
Lydéric Bocquet Jean-Pierre Hansen Jaroslaw Piasecki 《Journal of statistical physics》1994,76(1-2):527-548
The friction coefficient exerted by a hard-sphere fluid on an infinitely massive Brownian sphere is calculated for several size ratios , where and are the diameters of the Brownian and fluid spheres, respectively. The exact microscopic expression derived in part I of this work from kinetic theory is transformed and shown to be proportional to the time integral of the autocorrelation function of the momentum transferred from the fluid to the Brownian sphere during instantaneous collisions. Three different methods are described to extract the friction coefficient from molecular dynamics simulations carried out onfinite systems. The three independent methods lead to estimates of which agree within statisticalerrors (typically 5%). The results are compared to the predictions of Enskog theory and of the hydrodynamic Stokes law. The former breaks down as the size ratio and/or the packing fraction of the fluid increase. Somewhat surprisingly, Stokes' law is found to hold withstick boundary conditions, in the range 1/4.5 explored in the present simulations, with a hydrodynamic diameterd=. The analysis of the moleuclar dynamics data on the basis of Stokes' law withslip boundary conditions is less conclusive, although the right trend is found as / increases. 相似文献