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81.
多体刚性椭球模型是一种比较精确的描述氦原子与钠分子碰撞的理论模型.本文用多体刚性椭球模型计算了不同能量下He的同位素原子3He,4He,7He,10He与Na2分子碰撞的转动激发积分散射截面,表明增加椭球等势面个数可以得到更准确的转动激发积分散射截面;总结出3He,4He,7He,10He-Na2碰撞体系转动激发积分散射截面随相对入射能量和体系约化质量变化的规律;讨论了相对入射能量为100meV时,相互作用势的不同区域对4He-Na2碰撞体系转动激发积分散射截面的影响情况. 相似文献
82.
Three hydrogen bonding complexes of the gauche‐1PA dimer (GG), trans‐1PA dimer (TT) and mixed dimer (GT) have been calculated for the geometry conformations and excited‐state energies. The electron distribution at the site of C‐O of H‐donor moiety in HOMO transfers to the direction of O‐H of H‐acceptor moiety in LUMO. The hydrogen bond between two 1PAs is the bridge of the intermolecular charge transfer. By the Zhao and Han's excited‐state hydrogen bonding dynamics rule, the first excited‐state hydrogen bonding change has been discussed without optimizing the excited‐state geometry conformations. According to the distinct difference between GT and GG (TT), we concluded that two gauche‐1PA monomers of one dimer are transformed at the same time to two trans‐1PA monomers. 相似文献
83.
Jaewoong Kim 《Linear and Multilinear Algebra》2017,65(6):1260-1275
In this paper, we study several properties for mono-weakly hyponormal 2-variable weighted shifts. First, we consider propagation phenomena for mono-weakly hyponormal (resp. mono-polynomially hyponormal) 2-variable weighted shifts. Next, we contemplate the mono-weak hyponormality under the Schur product. Finally, we study whether the mono-weak hyponormality is invariant under powers. 相似文献
84.
《Journal of mass spectrometry : JMS》2017,52(4):204-209
We present the application of the extended desolvating capillaries for increasing the degree of the gas‐phase hydrogen/deuterium exchange reaction at atmospheric pressure. The use of the extended capillaries results in the increase of the time that ions spend in the high pressure region, what leads to the significant improvement of the efficiency of the reaction. For the small protein ubiquitin, it was observed that for the same temperature, the number of exchanges increases with the decrease of the charge state so that the lowest charge state can exchange twice the number of hydrogen than the highest one. With the increase of the temperature, the difference decreases, and eventually, the number of exchanges equalizes for all charge states. The value of this temperature and the corresponding number of exchanges depend on the geometric parameters of the capillary. Further increase of the temperature leads to the thermal dissociation of the protein ion. The observed b/y fragments are identical to those produced by collision‐induced dissociation performed in the ion trap. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
85.
We study the Goos-Hänchen (GH) shifts for Dirac fermions in graphene scattered by a triangular double barrier potential. The massless Dirac-like equation was used to describe the scattered fermions by such potential configuration. Our results show that the GH shifts is affected by the geometrical structure of the double barrier. In particular the GH shifts change sign at the transmission zero energies and exhibit enhanced peaks at each bound state associated with the double barrier when the incident angle is less than the critical angle associated with total reflection. 相似文献
86.
Normal halogen dependence of 13C NMR chemical shifts of halogenomethanes revisited at the four‐component relativistic level
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Dmitry O. Samultsev Yury Yu. Rusakov Leonid B. Krivdin 《Magnetic resonance in chemistry : MRC》2016,54(10):787-792
The ‘Normal Halogen Dependence’ of 13C NMR chemical shifts in the series of halogenomethanes is revisited at the four‐component relativistic level. Calculations of 13C NMR chemical shifts of 70 halogenomethanes have been carried out at the density functional theory (DFT) and MP2 levels with taking into account relativistic effects using the four‐component relativistic theory of Dirac‐Coulomb within the different computational methods (4RPA, 4OPW91) and hybrid computational schemes (MP2 + 4RPA, MP2 + 4OPW91). The most efficient computational protocols are derived for practical purposes. Relativistic shielding effect reaches as much as several hundreds of ppm for heavy halogenomethanes, and to account for this effect in comparison with experiment at the qualitative level, relativistic Dyall's basis sets of triple‐zeta quality or higher are to be used within the framework of the four‐component relativistic theory taking into account solvent effects. Relativistic geometrical optimization (as compared with the non‐relativistic level) is essential for the molecules containing at least two iodines at one carbon atom. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
87.
Roy E. Hoffman Noach Treitel Mordecai Rabinovitz 《Magnetic resonance in chemistry : MRC》2001,39(8):489-494
Isotope shifts are a well-established tool for structural analysis by NMR. The substitution of a protium with a deuterium is the most widely studied of these effects. However, such studies call for specific deuteration that requires complex synthetic techniques owing to the low natural abundance of deuterium. 13C occurs at a higher natural abundance and couples strongly with its attached proton. We have developed and refined a method to reliably observe these much smaller shifts without needing to resort to chemical synthesis. We show that carbon induced isotope shifts reflect structural features. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
88.
采用单组态坐标模型,应用由对角化d3能量矩阵而获得的波函数,同时考虑了自旋-轨道相互作用和电-声子耦合,并定量计入了4T2与2T1各电子态对R线的影响以及局域压缩率和整体压缩率之间的差异,从微观的角度,研究了GSGG∶Cr3+低温下光谱结构的特点以及压力导致的R1线和4T2宽带的移位.理论计算的结果与实验符合较好,R线的常压位置及其分裂、R1线的压致移位及其"反转"现象和4T2宽带的压致移位都得到了合理的解释. 相似文献
89.
Ch. Lisdat N. Vanhaecke D. Comparat P. Pillet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):299-309
Two-photon photoassociation spectra in a Λ-type excitation scheme are analysed under the systematically varied experimental conditions of frequency detunings and laser
intensities. Line shape fits are presented as well as the investigation of intensity and detuning dependent line shifts. From
both we determine the attained spectroscopic precision, that is corrected for a systematic line shift due to the thermal distribution
of atoms in the trap. An energy correction for this effect is given. Information about the feasibility of generating translationally
cold molecules in a well defined rotational and vibrational level by the photoassociation process is derived from the analysis.
Received 21 May 2002 Published online 15 October 2002
RID="a"
ID="a"Current address e-mail: christian.lisdat@ptb.de
RID="b"
ID="b"e-mail: pierre.pillet@lac.u-psud.fr 相似文献
90.
Recent measurements revealed that commercial magnesium standard solutions showed isotopic abundance variations, which cannot clearly be distinguished from each other by calibrating against the only available isotopic reference material, SRM 980, or reference materials made from SRM 980 like IRMM-009. Therefore new SI-traceable magnesium isotopic reference materials are required. 相似文献