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991.
A. Bartelt S. Minemoto C. Lupulescu Š. Vajda L. Wöste 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):127-131
We have performed adaptive feedback optimization of phase-shaped femtosecond laser pulses to control the wavepacket dynamics
of small mixed alkali-metal clusters. An optimization algorithm based on Evolutionary Strategies was used to maximize the
ion intensities. The optimized pulses for NaK and Na2K converged to pulse trains consisting of numerous peaks. The timing of the elements of the pulse trains corresponds to integer
and half integer numbers of the vibrational periods of the molecules, reflecting the wavepacket dynamics in their excited
states.
Received 4 December 2001 相似文献
992.
M. Schnürer S. Ter-Avetisyan H. Stiel U. Vogt W. Radloff M. Kalashnikov W. Sandner P.V. Nickles 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):331-335
Using 50 fs ( ∼ 2×1018 W/cm2) and 2 ps ( ∼ 5×1016 W/cm2) pulses from a Ti:Sa multi-TW laser at 800 nm wavelength large Xe-clusters ( 105...106 atoms per cluster) have been excited. Absolute yield measurements of EUV-emission in a wavelength range between 10 nm and
15 nm in combination with cluster target variation were carried out. The ps-laser pulse has resulted in about 30% enhanced
and spatially more uniform EUV-emission compared to fs-laser excitation. Circularly polarized laser light instead of linear
polarization results in enhanced emission which is probably caused by electrons gaining higher energies by the polarization
dependent optical field ionization process. An absolute emission efficiency at 13.4 nm of up to 0.8% in 2π sr and 2.2% bandwidth
has been obtained.
Received 11 January 2001 and Received in final form 27 March 2001 相似文献
993.
A. Glotov O. Knospe R. Schmidt E.E.B. Campbell 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):333-336
New experimental data is reported for the absolute cross sections for the fusion reaction channel in single gas-phase collisions
between fullerenes. The experimental data is compared with the results of quantum mechanical and classical molecular dynamics
simulations as well as with simple models. Quantum molecular dynamics simulations are in very good quantitative agreement
with the experimental data. The overall dynamical behaviour can be well-described qualitatively in the framework of simple
models.
Received 2 October 2000 相似文献
994.
C. Yannouleas U. Landman A. Herlert L. Schweikhard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):81-85
Using Penning-trap experiments and a shell-correction method incorporating ellipsoidal shape deformations, we investigate
the formation and stability patterns of trianionic gold clusters. Theory and experiment are in remarkable agreement concerning
appearance sizes and electronic shell effects. In contrast to multiply cationic clusters, decay of the trianionic gold clusters
occurs primarily via electron autodetachment and tunneling through a Coulomb barrier, rather than via fission.
Received 9 January 2001 相似文献
995.
光沉积法合成纳米金属Pd负载的MCM-TiO2及其光催化性质研究 总被引:9,自引:0,他引:9
用光沉积方法由PdCl42-和Ti修饰的MCM-41合成了纳米钯团簇Pd/MCM-TiO2,用XPS,N2吸脱附等温线,UV-Vis和Raman光谱对其结构进行了表征.将该团簇用于苯酚的光降解和Cr(Ⅵ)还原为Cr(Ⅲ)的反应中,表现出较高的光催化活性. 相似文献
996.
笼状氮化铝团簇的结构特征 总被引:1,自引:1,他引:0
建立了一种设计笼状氮化铝团簇的原则与方法,以此设计了(AlN)_n (n = 2 ~ 4)团簇的几何结构。采用量子化学AM1,HF/STO-3G和HF/LANL2DZ方法,对设计 的所有分子的同分异构体进行了优化,筛选出了低能量构型。完成了最低能量构型 结合能和能量二次差分值的计算,找到了(AlN)_n团簇的稳定性规律。用密度泛函 理论(DFT)的B3LYP/6-31G方法,对(AlN)_n (n = 8 ~ 15)等8种团簇进行了验 证性的计算,所得结果与HF/LANL2DZ方法一致。为下一步在实验上合成较大尺寸( AlN)_n团簇提供了理论依据。 相似文献
997.
Xu Xuesong 《化学物理学报(中文版)》2005,18(6):947-951
The structure and growth trend of the protonated acetophenone-water clusters have been investigated using the DFT-B3LYP method combined with the standard 6-31+G(d,p) basis set. In order to obtain more accurate single-point energy the B3LYP/6-311++G(3df,2p) method was adapted. The results show that the formation of H+C8H8O-H2O is a barrierless reaction process and the equilibrium distance between the proton and the O atom in C8H8O molecule is 1.015 A. For H+C8H8O-(H2O)n(n=1,2,3) clusters, the proton lies between the acetophenone molecule C8H8O and the water molecule H2O. The distance between the proton and the O atom of the C8H8O molecule increased from n=1 to n=3; C8H8O-H+-H2O can be regarded as an solvation shell. For H+C8H8O (H2O)n (n=4,5,6,7,8) clusters, the proton lies between the two H2O molecules forming a H5O2+ structure, C8H8O-H5O2+ is an important structure, which the other H2O molecules will attack from different sides. 相似文献
998.
The transport of monovalent ions through a charged membrane was investigated by percolation approach. Based on percolation concept and theory, the theoretical simulation was conducted for two-dimension (2D) and three-dimension (3D). The results showed that for 2D lattices there has a obviously skip or percolation threshold with charged components from 0.4 to 0.6, and for 3D lattices, such value is between 0.1-0.2. The simulative results were well conformed to those by Monto Carlo simulation for a random system. A practical charged membrane which prepared from the blends of sulphonated polyphenylene sulfide (SPPS)/poly(ether sulfone) (PES) can be considered as a 3D lattices. The experimental conductivity was related with a 3D simulation and the result showed the membrane has a transition from insulator to conductor at the ratio of charged components SPPS about 0.144. Obviously, this value falls in the range of a theoretical simulation for a 3D lattices. 相似文献
999.
The N-methylformamide(NMF)-water clusters were studied by ab inito calculations at MP2/6-31+G** and MP2 / 6-311 ++ G(d,p)levels. The equilibrium geometries and the dissociation channels and dissociation energies of both neutral and ionic NMF-H2O clusters are presented. For N-methylformamide,cis-form has lower energy than trans-form. In NMFH+,the proton prefers to link with the O atom of N-methylformamide. The results show that both cis- and trans- form of NMF can form a linear hydrogen bond with water. Although the energy of trans-NMF is higher than cis-NMF,trans-form exits more stably because it can form a double hydrogen bond with water. After the ionization of the NMF-H2O cluster,both the cis- and the trans-form will produce protonated products. 相似文献
1000.