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971.
Clarissa O. Da Silva Fbio Eduardo C. Teixeira Jos Andr T. Azevedo Edilson C. Da Silva Marco Antonio Chaer Nascimento 《International journal of quantum chemistry》1996,60(1):433-438
The two lower-lying electronic states (3Σ− and 5Σ−) of the BeC, MgC, and CaC molecules were investigated using restricted Hartree-Fock (RHF), generalized valence bond (GVB), and configuration interaction (CI) calculations to establish the relative ordering of those states as a function of the size of the alkaline-earth element. It is shown that as a result of the competition between bonding effects, which predominate for the 3Σ− states, and exchange effects, which stabilize the 5Σ− states, the ordering of these states can be reversed as we move from the Be to the Ca atom. For both the BeC and MgC molecules, the ground state was found to be a triplet X3Σ− state, but for the CaC molecule, the high-spin X5Σ− becomes more stable. © 1996 John Wiley & Sons, Inc. 相似文献
972.
Philipp Reineck Leevan Fremiot Trindade Jan Havlik Jan Stursa Ashleigh Heffernan Aaron Elbourne Antony Orth Marco Capelli Petr Cigler David A. Simpson Brant C. Gibson 《Particle & Particle Systems Characterization》2019,36(3)
Fluorescent nanodiamonds (FNDs) are vital to many emerging nanotechnological applications, from bioimaging and sensing to quantum nanophotonics. Yet, understanding and engineering the properties of fluorescent defects in nanodiamonds remain challenging. The most comprehensive study to date is presented, of the optical and physical properties of five different nanodiamond samples, in which fluorescent nitrogen‐vacancy (NV) centers are created using different fabrication techniques. The FNDs' fluorescence spectra, lifetime, and spin relaxation time (T1) are investigated via single‐particle confocal fluorescence microscopy and in ensemble measurements in solution (T1 excepted). Particle sizes and shapes are determined using scanning electron microscopy and correlated with the optical results. Statistical tests are used to explore correlations between the properties of individual particles and also analyze average results to directly compare different fabrication techniques. Spectral unmixing is used to quantify the relative NV charge‐state (NV? and NV0) contributions to the overall fluorescence. A strong variation is found and quantified in the properties of individual particles within all analyzed samples and significant differences between the different particle types. This study is an important contribution toward understanding the properties of NV centers in nanodiamonds. It motivates new approaches to the improved engineering of NV‐containing nanodiamonds for future applications. 相似文献
973.
Classical model for diffusion and thermalization of heavy quarks in a hot medium: memory and out-of-equilibrium effects 下载免费PDF全文
We consider a simple model for the diffusion of heavy quarks in a hot bath,modeling the latter by an ensemble of oscillators distributed according to either a thermal distribution or to an out-of-equilibrium distribution with a saturation scale.In this model it is easy to introduce memory effects by changing the distribution of oscillators:we model them by introducing a Gaussian distribution,dN/dω.which can be deformed continuously from a δ-function,giving a Markov dissipation, to a broad kernel with memory.Deriving the equation of motion of the heavy quark in the bath,we remark how dissipation comes out naturally as an effect of the back-reaction of the oscillators on the bath.Moreover,the exact solution of this equation allows to define the thermalization time as the time necessary to remove any memory of the initial conditions.We find that the broadening of the dissipative kernel,while keeping the coupling fixed,lowers the thermalization time.We also derive the fluctuation-dissipation theorem for the bath,and use it to estimate the kinematic regime in which momentum diffusion of the heavy quark dominates over drift.We find that diffusion is more important as long as K_0/ε is small,where K_0 and ε denote the initial energy of the heavy quark and the average energy of the bath,respectively. 相似文献
974.
Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science [1], catalysis [2], and electrochemistry [3], to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces [4, 5] and solid/liquid interfaces through an X-ray-transparent window [6–8]. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquid interface without needing a window [9]. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions [9]. These advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique. 相似文献
975.
Andrew Thomson Marco Ernst Ingrid Haedrich Jiadong Qian 《Optical and Quantum Electronics》2017,49(2):82
Photovoltaic cell and module manufactures optimise their products according to power measurements performed at a set of standard-test conditions. A key parameter for the financing of a solar project is yield under field or realistic conditions. Field testing modules is time consuming and costly. Hence, we develop a methodology for simulating PV module yield based on the optical, thermal and electrical properties of the components, and the module configuration regarding the cell spacing, interconnection and module layers. With our procedure, we model the performance of standard, half cell and encapsulant free modules in different locations. We present results using our cell to module yield framework for 16 different locations in Australia based on one-minute ground measured solar irradiance and ambient temperature values. We find low-light irradiance losses are directly correlated to the number of cloudy days at a given site. The majority of fielded losses are due to temperature effects, which can be predicted by the average temperature at 3 p.m. We note that wind speed is not accounted for and it will be incorporated in future studies. 相似文献
976.
977.
Rényi statistical entropy as a means to quantify mixing in two‐dimensional binary systems is presented. The use of Rényi entropies in defining the scale and intensity of segregation for mixing quality determination is analyzed. Finally, the relationship between the mixing process and the structures generated in the system is explored by using the Rényi entropy as an easy and computationally efficient method to calculate the system spectrum of fractal dimensions.
978.
We propose a scheme for determining a generalised scaling function, namely the Sudakov factor in a peculiar double scaling limit for high spin and large twist operators belonging to the sl(2) sector of planar SYM. In particular, we perform explicitly the all-order computation at strong 't Hooft coupling regarding the first (contribution to the) generalised scaling function. Moreover, we compare our asymptotic results with the numerical solutions finding a very good agreement and evaluate numerically the non-asymptotic contributions. Eventually, we illustrate the agreement and prediction on the string side. 相似文献
979.
Roberto Boada María ángeles Laguna‐Marco Jesús Chaboy 《Journal of synchrotron radiation》2009,16(1):38-42
An X‐ray magnetic circular dichroism (XMCD) study performed at the Ho L2,3‐edges in Ho6Fe23 as a function of temperature is presented. It is demonstrated that the anomalous temperature dependence of the Ho L2‐edge XMCD signal is due to the magnetic contribution of Fe atoms. By contrast, the Ho L3‐edge XMCD directly reflects the temperature dependence of the Ho magnetic moment. By combining the XMCD at both Ho L2‐ and L3‐edges, the possibility of determining the temperature dependence of the Fe magnetic moment is demonstrated. Then, both μHo(T) and μFe(T) have been determined by tuning only the absorption L‐edges of Ho. This result opens new possibilities of applying XMCD at these absorption edges to obtain quantitative element‐specific magnetic information that is not directly obtained by other experimental tools. 相似文献
980.
Jesús Chaboy María ángeles Laguna‐Marco Cristina Piquer Roberto Boada Neculai Plugaru Hiroshi Maruyama Naomi Kawamura 《Journal of synchrotron radiation》2009,16(3):405-412
An X‐ray magnetic circular dichroism (XMCD) study performed at the rare‐earth L2,3‐edges in the RxR1?x′Al2 compounds is presented. It is shown that both R and R′ atoms contribute to the XMCD recorded at the L‐edges of the selected rare‐earth, either R or R′. The amplitude of the XMCD signal is not directly correlated to the magnetization or to the value of the individual (R, R′) magnetic moments, but it is related to the molecular field acting on the rare‐earth tuned in the photoabsorption process. This result closes a longstanding study of the origin of the XMCD at the L‐edge of the rare‐earths in multi‐component systems, allowing a full understanding of the exact nature of these signals. 相似文献