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81.
Luigi Fabbrizzi Maurizio Licchelli Piersandro Pallavicini Luisa Parodi 《Angewandte Chemie (International ed. in English)》1998,37(6):800-802
Simply by changing the pH value, the side chain of complex 1 can be reversibly moved between two positions. Coordination to the metal center through the nitrogen atom of the side chain at moderate pH values is accompanied by a decrease in fluorescence intensity (from IF=100% to IF=60%). A further decrease is observed upon deprotonation of the bound water molecule at higher pH (IF≤2%). Therefore, 1 can be seen as a molecular three-position switch. 相似文献
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Bin Yang Marina Lledos Riaz Akhtar Giuseppe Ciccone Long Jiang Emanuele Russo Sunil Rajput Chunyu Jin Maria Galini Faidra Angelereou Thomas Arnold Jonathan Rawle Massimo Vassalli Maria Marlow Dave J. Adams Mischa Zelzer 《Chemical science》2021,12(42):14260
Controlling supramolecular self-assembly across multiple length scales to prepare gels with localised properties is challenging. Most strategies concentrate on fabricating gels with heterogeneous components, where localised properties are generated by the stimuli-responsive component. Here, as an alternative approach, we use a spiropyran-modified surface that can be patterned with light. We show that light-induced differences in surface chemistry can direct the bulk assembly of a low molecular weight gelator, 2-NapAV, meaning that mechanical gel properties can be controlled by the surface on which the gel is grown. Using grazing incidence X-ray diffraction and grazing incidence small angle X-ray scattering, we demonstrate that the origin of the different gel properties relates to differences in the architectures of the gels. This provides a new method to prepare a single domain (i.e., chemically homogeneous) hydrogel with locally controlled (i.e., mechanically heterogeneous) properties.A mechanical pattern is created in a hydrogel film by pre-patterning the underlying surface chemistry. This allows spatial variation of the viscous component of the gel, controlling dissipative forces in the gel film without altering gel chemistry. 相似文献
84.
Emanuele Pugliese Claudio Castellano Matteo Marsili Luciano Pietronero 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(3):319-327
We introduce and study a model of an interacting population of agents who collaborate in groups which compete for limited
resources. Groups are formed by random matching agents and their worth is determined by the sum of the efforts deployed by
agents in group formation. Agents, on their side, have to share their effort between contributing to their group’s chances
to outcompete other groups and resource sharing among partners, when the group is successful. A simple implementation of this
strategic interaction gives rise to static and evolutionary properties with a very rich phenomenology. A robust emerging feature
is the separation of the population between agents who invest mainly in the success of their group and agents who concentrate
in getting the largest share of their group’s profits. 相似文献
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The equilibrium free energy difference between two long-lived molecular species or "conformational states" of a protein (or any other molecule) can in principle be estimated by measuring the work needed to shuttle the system between them, independent of the irreversibility of the process. This is the meaning of the Jarzynski equality (JE), which we test in this paper by performing simulations that unfold a protein by pulling two atoms apart. Pulling is performed fast relative to the relaxation time of the molecule and is thus far from equilibrium. Choosing a simple protein model for which we can independently compute its equilibrium properties, we show that the free energy can be exactly and effectively estimated from nonequilibrium simulations. To do so, one must carefully and correctly determine the ensemble of states that are pulled, which is more important the farther from equilibrium one performs simulations; this highlights a potential problem in using the JE to extract the free energy from forced unfolding experiments. The results presented here also demonstrate that the free energy difference between the native and denatured states of a protein measured in solution is not always equal to the free energy profile that can be estimated from forced unfolding simulations (or experiments) using the JE. 相似文献
88.
Scifoni E Gianturco FA Grebenshchikov SY Schinke R 《The Journal of chemical physics》2006,125(16):164304
Ab initio quantum calculations have been carried out on the helium ionic trimer. The potential energy surface is accurately fitted, especially in the vicinity of the three equivalent minima. The spectrum of bound states for the zero angular momentum is computed and analyzed in detail. Energies and wave functions reveal several interesting features related to the fact that He3+ represents one of the few homonuclear ionic trimers that are linear in their ground vibrational state. At low energies, the triply degenerate eigenfunctions are localized at the potential minimum. With growing excitation energy, however, the wave functions exhibit stronger spatial delocalization. 相似文献
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