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81.
C. Zandalazini P. Esquinazi G. Bridoux J. Barzola-QuiquiaH. Ohldag E. Arenholz 《Journal of magnetism and magnetic materials》2011,323(22):2892-2898
We studied the magnetic behavior of bilayers of multiferroic and nominally antiferromagnetic o-YMnO3 (375 nm thick) and ferromagnetic La0.7Sr0.3MnO3 and La0.67Ca0.33MnO3 (8…225 nm), in particular the vertical magnetization shift ME and exchange-bias field HE for different thickness and magnetic dilutions of the ferromagnetic layer at different temperatures and cooling fields. We have found very large ME shifts equivalent to up to 100% of the saturation value of the o-YMO layer alone. The overall behavior, including XMCD magnetization shift measured at the Mn-L edge of the LSMO layer only, indicates that the properties of the ferromagnetic layer contribute substantially to the ME shift and that this does not correlate straightforwardly with the measured exchange-bias field HE. 相似文献
82.
Yan-Jun Li Peng Wang Jing-Fu Ni Liang Meng Xiao-Bo Wang Chun-Qi Sheng Hong-Nian Li Wen-Hua Zhang Yang Xu Fa-Qiang Xu Jun-Fa Zhu 《Journal of Electron Spectroscopy and Related Phenomena》2011,184(7):414-419
We have measured and analyzed the photoemission spectra (PES) of a C70 film in the photon energy region from 13.4 eV to 98.4 eV. The photoelectron intensities of two C 2p π-derived features (denoted by A and B) oscillate regularly in the whole energy region with some fine structures below ∼30 eV. To obtain the detailed information of the oscillations, we have developed a sophisticated but practical procedure for intensity calculation. The procedure consists of two core concepts. The first is ascribing the PES features to their corresponding molecular orbitals with the help of density functional calculations. The second is a background subtraction algorithm. With this procedure, we obtained the oscillating behavior for individual features (A and B), which is by and large consistent with the predictions based on the spherical symmetric approximation although C70 has the ellipsoidal shape. Owing to the solid state effect, the oscillating amplitudes of the A/B intensity ratios are smaller than those of gas phase C70, but an orbital shift reported recently was not observed on our sample. The oscillating curve of a deeper feature, which consists of both σ and π states, are also reported. 相似文献
83.
Supramolecular Polymers Self‐Assembled from trans‐Bis(pyridine) Dichloropalladium(II) and Platinum(II) Complexes 下载免费PDF全文
Mingming Chen Chengsha Wei Jiaojiao Tao Xibo Wu Dr. Ningdong Huang Prof. Dr. Guobin Zhang Prof. Dr. Liangbin Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2812-2818
Two structurally similar trans‐bis(pyridine) dichloropalladium(II)‐ and platinum(II)‐type complexes were synthesized and characterized. They both self‐assemble in n‐hexane to form viscous fluids at lower concentrations, but form metallogels at sufficient concentrations. The viscous solutions were studied by capillary viscosity measurements and UV/Vis absorption spectra monitored during the disassembly process indicated that a metallophilic interaction was involved in the supramolecular polymerization process. For the two supramolecular assemblies, uncommon continuous porous networks were observed by using SEM and TEM revealed that they were built from nanofibers that fused and crosslinked with the increase of concentration. The xerogels of the palladium and platinum complexes were carefully studied by using synchrotron radiation WAXD and EXAFS. The WAXD data show close stacking distances driven by π–π and metal–metal interactions and an evident dimer structure for the platinum complex was found. The coordination bond lengths were extracted from fitting of the EXAFS data. Moreover, close PtII–PtII (PdII–PdII) and Pt?Cl (Pd?Cl) interactions proposed from DFT calculations in the reported oligo(phenylene ethynylene) (OPE)‐based palladium(II) pyridyl supramolecular polymers were also confirmed by using EXAFS. The PtII–PtII interaction is more feasible for supramolecular interaction than the PdII–PdII interaction in our simple case. 相似文献
84.
Chaosheng Yuan Lei Su Kun Yang Zijiong Li Xuerui Cheng Weiqing Zhou Liangbin Li 《Journal of Sol-Gel Science and Technology》2014,72(2):344-350
Sol–gel transition behavior of ionic liquid gel based on poly (ethylene glycol) (PEG) and ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate [EMIM][EtSO4] has been investigated under the pressure up to 250 MPa. The Temperature versus Pressure phase diagram of PEG/[EMIM][EtSO4] gel is constructed, and it indicates that the melting point is an increasing function of pressure. Based on the phase diagram, the PEG/[EMIM][EtSO4] gels are prepared by cooling under the pressure of 300 MPa and atmospheric pressure, respectively. From the differential scanning calorimetry result of the recovered samples, it is found that PEG/[EMIM][EtSO4] gel prepared under high pressure has a higher crystallinity and smaller crystal size polymer network, comparing with under atmospheric pressure. The cyclic voltammograms and impedance spectra tests indicate that the PEG/[EMIM][EtSO4] gel prepared under high pressure exhibit higher ionic conductivity comparing with atmospheric pressure. It could be speculated these excellent properties might be attributed to the loose gel structure and high ionic density induced by high pressure. 相似文献
85.
Here we employ high-quality samples of (Sr1−xLax)CuO2 and (Nd2−xCex)CuO4 and XANES spectroscopy at O-K, Cu-L2,3 and Ce-M4,5 edges to gain comprehensive understanding of the electronic structure and doping in n-type high-Tc superconductors. Not only common but also slightly different features are revealed for the two systems. From O-K-edge spectra, the UHB is found essentially independent of the electron-doping level for both the systems, in line with our understanding that the doped electrons do not go to the O site in n-type copper-oxide superconductors. Another common observation is that the main CuII peak at the Cu-L3 edge (due to transitions to the CuII-3d orbitals) systematically decreases in intensity upon electron doping, hence verifying the fact that the doped electrons go to the Cu site. The difference then between the two systems is that in (Sr1−xLax)CuO2 the weaker CuII peak due to transitions to the CuII-4s orbital depends on the degree of doping. Moreover, it was found that with increasing x, electron density increases much faster in (Sr1−xLax)CuO2 than in (Nd2−xCex)CuO4. This is a consequence of two phenomena: a tiny increase in oxygen content concomitant to the CeIV-for-NdIII substitution and the somewhat lower Ce-valence value of +3.8 compared to the nominal tetravalent state. 相似文献
86.
Tonia M. Di Palma Maria V. Prati Antonio Borghese 《Journal of the American Society for Mass Spectrometry》2009,20(12):2192-2198
Here we report on a laser plasma-based tunable VUV photoionization time-of-flight (TOF) mass spectrometer conceived mainly
to study complex gaseous mixtures. Ionizing photons at tunable vacuum UV (VUV) wavelengths are generated by a gas-target laser-produced
plasma, spectrally dispersed in the range 100–160 nm and efficiently focused onto a sample molecular beam. As a test case,
we studied the exhaust gas of a four-stroke moped, a typical example of a complex gaseous mixture. Due to the VUV “soft” ionization,
the mass spectra are less congested and more easily interpretable. Substituted benzene derivatives are found to give the most
intense signals. Several aliphatic hydrocarbons are also detected. The use of tunable VUV radiation allowed the investigation
of the contribution of isomers in the mass spectrum from the onset and shape of the photoionization efficiency spectra. Semiquantitative
analysis was performed using known literature data detailing the photoionization cross sections. Our findings suggest that
using combined data on the mass/photoionization efficiency spectra may be very helpful for a comprehensive analysis of complex
gaseous mixtures. 相似文献
87.
The structural, elastic, mechanical, electronic, optical properties and effective masses of CuMIIIBO2 (MIIIB = Sc, Y, La) compounds have been investigated by the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory under local density approximation. The equilibrium structural parameters are in good agreement with previous experimental and theoretical data. To our knowledge, there are no available data of elastic constants for comparison. The bulk, shear and Young's modulus, ratio of B/G, Poisson's ratio and Lamé's constants of CuMIIIBO2 have been studied. The electronic structures of CuMIIIBO2 are consistent with other calculations. The population analysis, charge densities and effective masses have been shown and analyzed. The imaginary and real parts of the dielectric function, refractive index and extinction coefficient of CuMIIIBO2 are calculated. The interband transitions to absorption of CuMIIIBO2 have been analyzed. 相似文献
88.
A series of impulse-type inputs has been extensively used to evaluate the critical response of an elastoplastic structure subjected to diverse types of pulse-type inputs, including a near-fault ground motion. In this paper, we consider the critical double-impulse input for a single-degree-of-freedom elastic–perfectly plastic structure, and study effects of structural uncertainties. When the natural frequency (or, equivalently, the stiffness) is fixed, the critical response of the structure does not necessarily decrease as the yield deformation (or, equivalently, the yield force) increases. As the first contribution, we give through investigation of this non-monotonicity property. Moreover, we present a systematic method for finding the worst-case scenario when the yield deformation and the stiffness of a structure assumed to be uncertain simultaneously. Numerical examples are presented to illustrate that the robustness of a structure does not necessarily improve when the yield deformation and/or the yield force is increased. 相似文献
89.
90.
Kai Zhang De-e Li Peiping Zhu Qingxi Yuan Wanxia Huang Xiaosong Liu Youli Hong Gun Gao Xin Ge Hongzhang Zhou Ziyu Wu 《Analytical and bioanalytical chemistry》2010,397(6):2143-2148
The investigation of the internal morphology of insects is usually performed using classical microtomy yielding optical micrographs of stained thin sections. The achievement of high-quality cross sections for microtomy is time-consuming and the risk of damaging sections is unavoidable. Moreover, the approach is impractical, in particular when quick acquisition of 3D structural information is required. Recently, X-ray computed microtomography (micro-CT) with a high spatial resolution was considered as a potential tool for the morphological classification of insects. We used micro-CT to investigate Quedius beesoni Cameron at the cellular length scale. This method provides a new powerful and nondestructive approach to obtain 3D structural information on the biological organization of insects. The preliminary images presented in this contribution clearly reveal the endoskeleton and the muscles of the head and the thorax with a full 3D structure. We also reconstructed the 3D structure of the brain of Quedius beesoni Cameron, and this is the first reconstruction in Staphylinidae, which will be a great advancement for morphological and phylogenic research. We claim that both the spatial resolution and the contrast characteristic of micro-CT imaging may fulfill the requirements necessary for zoological insect morphology and phylogeny, in particular, when a classification of a rare and unique insect specimen is required. 相似文献