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991.
Jie Deng Dominik Bezold Henning J. Jessen Andreas Walther 《Angewandte Chemie (International ed. in English)》2020,59(29):12084-12092
Fuel‐driven self‐assemblies are gaining ground for creating autonomous systems and materials, whose temporal behavior is preprogrammed by a reaction network. However, up to now there has been a lack of simple external control mechanisms of the transient behavior, at best using remote and benign light control. Even more challenging is to use different wavelengths to modulate the reactivity of different components of the system, for example, as fuel or building blocks. Success would enable such systems to navigate along different trajectories in a wavelength‐dependent fashion. Herein, we introduce the first examples of light control in ATP‐fueled, dynamic covalent DNA polymerization systems organized in an enzymatic reaction network of concurrent ATP‐powered ligation and restriction. We demonstrate concepts for light activation and modulation by introducing caged ATP derivatives and caged DNA building blocks, making it possible to realize light‐activated fueling, self‐sorting in structure and behavior, and transition across different wavelength‐dependent dynamic steady states. 相似文献
992.
Sebastian Loescher Andreas Walther 《Angewandte Chemie (International ed. in English)》2020,59(14):5515-5520
We introduce divalent 3D DNA origami cuboids as truly monodisperse colloids and harness their ability for precision functionalization with defined patches and defined numbers of supramolecular binding motifs. We demonstrate that even adamantane/β‐cyclodextrin host/guest inclusion complexes of moderate association strength can induce efficient supracolloidal fibrillization at high dilution of the 3D DNA Origami as a result of cooperative multivalency. We show details on the assembly of Janus and non‐Janus 3D DNA origami into supracolloidal homo‐ and heterofibrils with respect to multivalency effects, electrostatic screening, and stoichiometry. We believe that the merger of 3D DNA origami with colloidal self‐assembly and supramolecular motifs provides new synergies at the interface of these disciplines to better understand multivalency effects, to promote structural complexity, and add non‐DNA assembling and switching mechanisms to DNA nanoscience. 相似文献
993.
Ali Vahidifar Elnaz Esmizadeh Denis Rodrigue Hossein A. Khonakdar Udo Wagenknecht 《先进技术聚合物》2020,31(7):1508-1518
A novel and conventional closed cell polyisoprene rubber (IR) foams were produced by a single step limited‐expansion and two step unlimited‐expansion foaming process, respectively. The effect of 3 to 12 part per hundred rubber (phr) of azodicarbonamide (ADC) foaming agent on their structure and properties of developed novel foams were studied. In developed novel foams, the density was strangely independent of ADC content; however, the cell sizes conversely related to ADC content and it decreased by 60% (555‐330 μm) and the internal cell pressure build up from 1 to 3.7 atm, which was related to pressure‐free foaming method. The both reasons of compressed gas trapped inside cells and constant density not only caused unique enhancement in novel foams mechanical properties as hardness and modulus but also improved their dynamic properties as hysteresis and elasticity. Results of conventional IR foams showed that, their foam density as well as dynamic and mechanical properties sharply decreased with increasing ADC content from 3 to 12 phr. For clear expression, in samples with 12 phr of ADC, novel developed foams have more foam density (180%), more hardness (240%), more modulus (290%), and smaller cell size (75%) than conventional foams. Finally, novel developed foams were super‐elastic material with no hysteresis and no plastic deformation while conventional foams had 40% hysteresis and 10% plastic deformation under the same compression conditions. 相似文献
994.
995.
996.
The rotational spectra of normal and 13C species of difluoromethane-argon have been investigated by molecular beam Fourier transform microwave spectroscopy. The obtained results allowed for the determination of the configuration of the complex, based on experimental data. The tunnelling splitting originated by van der Waals motions has been determined to be 193.740(1) and 162.16(8) MHz for the normal and 13C species, respectively. The two vibrational splittings have been used to evaluate a tunnelling barrier of 94(5) cm−1. The fluorine-fluorine nuclear spin-spin coupling constant has been determined, Daa = 0.19(1) MHz. 相似文献
997.
A. Frischbutter Ch. Janssen Ch. Scheffzük K. Walther K. Ullemeyer J. H. Behrmann A. N. Nikitin T. I. Ivankina H. Kern B. Leiss 《Physics of Particles and Nuclei》2006,37(1):S45-S68
Information on texture and residual stress in geological samples is very important for the calculation of physical properties connected with the evaluation of the geomechanical behavior of parts of the earths’s crust in connection with processes from human activities (mining, tunnelling) and natural processes of deformation (seismicity, earthquakes). Texture and stress are not independent of each other and in the general case should be analyzed together. Complications arise because geological samples are generally composed of several phases (minerals) whose elastic constants may be significantly different. Nevertheless, modern neutron diffractometers such as SKAT and EPSILON-MDS at the fast pulsed reactor IBR-2 at the FLNP of the JINR make it possible to obtain the needed diffraction patterns. This was shown especially for texture measurements on samples with quartz as the main component as well as for mica, feldspar, amphibole, and several other minerals. In order to extend strain measurements beyond samples composed of quartz, dolomite, and/or anhydrite to such frequently occurring minerals as feldspars and mica it would be necessary on the one hand to use Rietveld refinement with corrections due to texture and anisotropic peak broadening. With an increase in the number of mineral phases suitable for these diffractometers, it is in general necessary to improve the experimental conditions for SKAT and EPSILON-MDS, especially to significantly raise the flux of incident neutrons on the sample. 相似文献
998.
999.
S. Krückeberg G. Dietrich K. Lützenkirchen L. Schweikhard C. Walther J. Ziegler 《Hyperfine Interactions》1997,108(1-3):107-114
Doubly charged silver clusters Agn
2+, n=21, 22, 23, are produced by electron bombardment of an Agn
+ ensemble stored in a Penning trap. After mass selection the clusters are subjected to collision induced dissociation. The
fragmentation channels are determined by time-of-flight mass spectrometry after ejection of the resulting ion ensemble from
the trap. Monomer evaporation is the only decay path observed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
1000.