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排序方式: 共有318条查询结果,搜索用时 15 毫秒
261.
262.
I. Hjelte M. N. Piancastelli C. M. Jansson K. Wiesner O. Bjrneholm M. Bssler S. L. Sorensen S. Svensson 《Chemical physics letters》2003,370(5-6):781-788
We present evidence for ultra-fast dissociation of molecular ammonia when photo-excited to the N1s→4a1 core-hole state. This finding is based on resonant Auger spectroscopical results as well as qualitative arguments concerning the photon energy dependence of the Auger structures. Calculations of the excited state potential based on the Z+1 approximation were performed. Both the calculations and the measurements indicate that the most likely fragmentation pathway for the core excited ammonia molecules leads to NH2* and H fragments. 相似文献
263.
Smetana AB Klabunde KJ Marchin GR Sorensen CM 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7457-7464
While the activity of the SMAD powders is lower than that of pure silver nitrate, it has the ability to kill bacteria very effectively and over long periods of time. 相似文献
264.
Bonnier C Piers WE Parvez M Sorensen TS 《Chemical communications (Cambridge, England)》2008,(38):4593-4595
Fluoride abstraction from a BODIPY dye gives a well defined borenium ion which can be converted to a borenium hydride via treatment with DIBAL-H. 相似文献
265.
[structure: see text]. Phenanthrene analogues with internalized B-N moieties were found to afford blue light emission with good quantum efficiencies, whereas the isomeric species with peripheral B-N moieties displayed only UV emission behavior, like the all-carbon framework. 相似文献
266.
Feifel R Tanaka T Kitajima M Tanaka H De Fanis A Sankari R Karlsson L Sorensen S Piancastelli MN Prümper G Hergenhahn U Ueda K 《The Journal of chemical physics》2007,126(17):174304
The valence character of O 1s-->Rydberg excited O2 is investigated by means of participator Auger decay spectroscopy, performed at selected photon energies across the K-shell resonance region, and by means of partial ion yield x-ray absorption spectroscopy. For several of the excitation energies studied, the authors find substantial sigma*(4Sigmau-, 2Sigmau-) valence character being mixed with nssigma and npsigma (4Sigmau-, 2Sigmau-) Rydberg states. An experimental indication of a coupling between the channels associated with quartet and doublet ion cores is considered and discussed. New spectroscopic constants are derived for the singly ionized X 2Pig state of O2 based on the observation of at least 20 vibrational sublevels. 相似文献
267.
Gisselbrecht M Lindgren A Tchaplyguine M Burmeister F Ohrwall G Lundwall M Lundin M Marinho RR Naves de Brito A Svensson S Björneholm O Sorensen SL 《The Journal of chemical physics》2005,123(19):194301
Photofragmentation of small argon clusters with size below ten atoms is reported. In this size range significant modifications from the electronic properties and geometry take place. When tuning the photon energy through the argon 2p edge, the fragmentation pattern is changed. Specifically, cation dimer production is enhanced at the 2p(32)-->4s resonance, while above the 2p edge almost complete atomization is observed. In both cases, the widths of the peaks in the mass spectra indicate that a large amount of kinetic energy is imparted to the fragment due to the formation of multiply charged clusters. A model based on "Coulomb explosion"-charge separation, simply resulting in a complete atomization of the cluster with no dependence on the photon energy-is insufficient to explain the observed photofragmentation of small clusters. 相似文献
268.
Tchaplyguine M Marinho RR Gisselbrecht M Schulz J Mårtensson N Sorensen SL de Brito AN Feifel R Ohrwall G Lundwall M Svensson S Björneholm O 《The Journal of chemical physics》2004,120(1):345-356
A new approach for obtaining an estimate of the effective size of the free neutral clusters is proposed. The approach relies on an experimental measure of the surface and interior or "bulk" cluster atoms provided by the x-ray photoelectron spectroscopy and on a model for the attenuation of photoelectrons ejected from the bulk of the cluster as the result of the ionizing irradiation. The experimental part gives the ratio of the electron signal from the bulk cluster atoms to that from the cluster surface atoms for a wide range of cluster sizes and electron kinetic energies. The attenuated response of the bulk atoms is modeled using an exponential law with the cluster size and kinetic-energy-dependent electron escape depth as parameters. For the experimental size range, model-based calculations for Ar, Kr, and Xe clusters are presented. The cluster size estimates obtained from comparison of the model calculations and experimental results agree well with those determined from the parameters of the cluster creation process. The combination of experiment and modeling also makes it possible to estimate the effective escape depth for electron propagation in free clusters. For Ar, Kr, and Xe clusters of varying mean size, absolute determination of the surface and bulk electron binding energies of the core levels used in the experiments has also been made. 相似文献
269.
In a variation of the classical Ugi reaction, an acid-promoted reaction between imines and isocyanides forms both 3-aminoindoles and substituted indoxyls. A recently reported triflyl phosphoramide is shown to be critical to obtain high yields under mild conditions. 相似文献
270.
We present the Raman spectrum of pure liquid D2O at −27.0°C, 17°C lower than any previously reported Raman spectrum of liquid D2O. The liquid's OD stretch band at −27.0°C displays a prominent feature which is clearly analogous to the ν1 in-phase mode in D2O ice Ih providing strong evidence that the structure of cold liquid D2O's OD band is principally due to strong intermolecular coupling. Deeply supercooled liquid D2O displays this ν1 in-phase feature more clearly than deeply supercooled liquid H2O due to the smaller disparity in the D/O mass ratio compared to that of H/O which enhances this coupling. 相似文献