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11.
Zhang Yugeng 《光谱学快报》2013,46(9):1673-1679
The photoacoustic spectra of Co(H2EDTA)·3H20, Ca[Co(EDTA)H20]·4H20, Sr[Co(HEDTA)H20]2·4H20, Ba[Co(HEDTA)H20]2·4H20 complexes crystal are determined in the region of 300–800nm. In these spectra, the separations of absorption bands observed at 510nm and 650nm, the peak widths of 510nm band are variable in this series complexes. It is explained by the electron mutual effect, strength of ligand field and the symmetry of coordination group. The structure characters of these series complexes are also discussed.  相似文献   
12.
We report on transverse field (TF) Muon Spin Rotation (μSR) measurements on a single crystal of the hexagonal heavy fermion superconductor UNi2Al3 between 5 K and 300 K. From the measured muon Knight shift (KS) in the easy ( a , b )-plane and along the c-axis we extracted the local magnetic susceptibility tensor [0pt] , which arises from the nearest U-neighbors. By comparison with the bulk susceptibility [0pt] it is found that [0pt] and [0pt] agree well above 150 K but deviate considerably in the basal plane below 150 K, due to the disturbance introduced by the . We succeed in reproducing both [0pt] and [0pt] on the basis of a crystalline electric field (CEF)-approach assuming U to be in the tetravalent state. The disturbance introduced by the affects the CEF-Hamiltonian in an expected manner, suggesting strongly that a CEF-picture implying a rather local 5 f-electron wave function is indeed valid. Reanalyzing older data on UPd2Al3 we arrive at the same conclusion. A necessary condition for extracting the local susceptibility was the knowledge of the -site, this information was derived from the analysis of the TF-relaxation rates. At low temperatures we found about 30% of the implanted at the d-site and none at this site above 200 K. The majority fraction was found to be in a tunneling state over six m (or k)-sites around the b-site. No long range diffusion was seen up to room temperature. Received 20 April 1999  相似文献   
13.
Abstract

Fluorescence correlation spectroscopy (FCS) is an important biophysical technique. FCS is currently being used in many areas of biology to solve several scientific problems. Its properties such as detection at the single molecular level, higher sensitivity, and use of lower sample volume make FCS a promising molecular diagnostic tool. The promising applications of FCS extend from DNA kinetics/dynamics studies to the comprehensive understanding of receptor–ligand interactions. In this article, we review various promising biological applications of FCS.  相似文献   
14.
The state of CaOH was investigated using optical–optical double resonance spectroscopy. A combined least-squares fit of the double resonance transition data along with optical transition data and the millimeter-wave pure rotational data of the state was performed using an effective Hamiltonian. The spin–rotation constant was determined for the state for the first time. An analysis of these constants showed that the Ca–O bond length and spin–rotation parameter of the state have the smallest values of all the observed 2Σ+ states of CaOH. This evidence suggests the assignment of the state as arising from a Ca+ atomic orbital of mainly 5 character. This atomic orbital assignment was shown to be consistent with both previous work on CaF and recent theoretical calculations on CaOH.  相似文献   
15.
The electronic absorption spectra of crystals of the title componds were recorded and the experimental results were explained quantitatively with the ligand field theory and the radial wave function of bound Cu(II) cation. With these spactra, the range of magnetic interactions between two Cu(II) ions of the title compounds are discussed.  相似文献   
16.
The EPR g factors gi (i = x, y, z) for the interstitial Ti3+ in rutile are theoretically studied from the perturbation formulas of these parameters for a 3d1 ion in rhombically compressed octahedra. The ligand octahedron in the impurity center is found to be less compressed than that on the host interstitial site due to the Jahn-Teller effect. The local compression parameter (≈0.026) and the rhombic distortion angle δϕ′ (≈0.7°) around the impurity Ti3+ are smaller than the host values (≈0.091 and 3.5°). The theoretical g factors based on the above local structural parameters are in good agreement with the experimental data. In addition, the g factors for a tetragonal interstitial Ti3+ center are also reasonably interpreted.   相似文献   
17.
The different approximations that have been used in applying Bethe’s cluster model to the nematic-isotropic phase transition are examined. It is shown that the introduction of a higher order term in the mean field potential of an outer molecule of the cluster improves the consistency of the theory considerably. In particular, the importance of satisfying Chang’s relation is emphasized. Calculations are presented of the long and short range order parameters, heat of transition and specific heat for different values ofz, the number of nearest neighbours around any given molecule, for both nonpolar and antiparallel near neighbour correlations. Even the new mean field potential appears to be inadequate forz=3.  相似文献   
18.
1 INTRODUCTION  Organolanthanidecomplexeshavebeenextensivelystudied.However,thestud-iesofindenylrareearthcomplexeswererelativelylimited[1].Althoughaseriesoftri-indenyltetrahydrofuranatolanthanide((C9H7)3Ln·THF)havebeensynthesizedandstudiedbyTsutsuiandGyslingabout30yearsago[2],onlyafewcrystalstruc-turesofindenyllanthanidecomplexeshavebeenreported[1].Moreover,mostofthereportedindenyllanthanidecomplexesweresynthesisedbymetatheticalreactionsofanhydrouslanthanidetrichlorideswithindenyls…  相似文献   
19.
It has been proven qualitatively by a number of authors using variable temperature NMR experiments that most metal carbonyl complexes are nonrigid. A quantitative determination of the ligand exchange frequency ve is often achieved by a line shape analysis or by measurement of the transverse relaxation time T2 using the Carr-Purcell method. In the case of a “very fast” exchange, however, both methods prove unsuccessful. It is shown in this study that a simultaneous fit of IR or Raman spectra on the one hand and NMR spectra on the other can make possible the determination of ve for the “very fast” exchange and can also facilitate the determination of ve in “slow” and “medium” exchange cases considerably. The ligand exchange frequency thus found for Fe(CO)5, 1.1 × 1010s?1, is unexpectedly high; comparison with variable temperature measurements on solid Fe(CO)5, yields similar energy barriers. A mechanism of exchange closely related to the “Berry mechanism” is proposed. Finally the consequences of this surprisingly large ligand exchange rate are discussed with respect to IR band assignments for molecular “fragments” M(CO)x (where x=coordination number, and M is a transition metal, typically lanthanoid or actinoid).  相似文献   
20.
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