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31.
朱用文 《烟台大学学报(自然科学与工程版)》1998,(4)
确定了一些基本图的〔强〕自同态摹群的基数,并在证明过程中实际上确定了这些摹群的全部元素,同时发现确定一些极其简单的图之自同态摹群却是极其困难的事情,有时甚至导致一些一般的组合难题. 相似文献
32.
Carbon isotope anomaly in marbles associated with eclogites from the Dabie Mountains 总被引:1,自引:0,他引:1
This is a report of carbon isotope anomaly in marbles associated with the UHP eclogites from the Dabie Mountains. The results
place constraints on the degree of crust-mantle interaction during the UHP metamorphism. 相似文献
33.
极性晶体膜中极化子的性质 总被引:1,自引:0,他引:1
使用格林函数法研究在极性晶体膜中极化子自能的一些性质.对GaAs进行了计算,结果表明:在绝对零度时,极性晶体膜中电子与体纵光学声子相互作用能的绝对值随极性晶体膜的厚度的增加而增加,随后几乎保持不变. 相似文献
34.
35.
对化学法清洗硅片过程中消除颗粒的机理作了定量的探讨。颗粒的清除是由于化学蚀刻和颗粒与表面排斥力共同作用的结果。首次提出了最浅蚀刻深度和最小蚀刻速度的概念。最浅蚀刻深度可通过颗粒与表面间作用能的关系进行计算。是小蚀刻速度则可通过蚀刻侧形进行计算。研究结果对于优化化学法清洗过程和设计高性能清洗液都具有重要意义。 相似文献
36.
苏世同 《吉首大学学报(自然科学版)》1997,(3)
本文从身心交互的基点出发,选取“心理养身”的新视角,对身与心的各种辩证关系、各个侧面以及身心交互的本质等进行了较详细地论述,不仅在某一层次上系统地揭示了人类心理行为的生理与社会根源,而且明确地提出与剖析了进行心理养身的科学养身之道。这对于促进主体心身的健康发展,无疑是有一定价值的。 相似文献
37.
John D. Watts Miroslav Urban Rodney J. Bartlett 《Theoretical chemistry accounts》1995,90(5-6):341-355
Summary This paper reports a series of coupled-cluster (CC) calculations through CCSDT on the theoretically challenging ground state of the BeO molecule. Along with CC methods, quadratic configuration interaction (QCI) approximations to CC theory have been used (QCISD and QCISD(T)), which show several dramatic failings. Equilibrium electrical properties (,
xx
, and
zz
) and basic spectroscopic properties (r
e, e,D
e, and infrared intensity (I)) have been computed. Basis set and electron correlation effects are analyzed in order to arrive at accurate values of the dipole moment and polarizability, which are not known experimentally. For the dipole moment, we obtain a value of 6.25 D, with an uncertainty of about 0.1 D. For
xx
and
zz
, we suggest respective values of 32 and 36 atomic units (a.u.) and error bars of about 1 and 2 a.u. With extended basis sets, the spectroscopic propertiesr
e, e, andD
e are reproduced to high accuracy, which is the first time this has been achieved for this species byab initio methods. At the highest calculation levels,I is predicted to be very small. AlthoughI has not been measured, some support for this prediction comes from a recent infrared study of BeO-rare gas complexes. The QCI methods are shown to be much more sensitive to basis set, and even with large basis sets yield values of
zz
andI which differ from CC results by an order of magnitude and three orders of magnitude, respectively. These differences doubtless arise from the importance of single excitations (T
1) for this molecule, as several terms involvingT
1 are neglected in the QCISD approximation compared with CCSD. We also report CC calculations with Brueckner orbitals, which yield results similar to those obtained with restricted Hartree-Fock orbitals. 相似文献
38.
严继民 《中国科学B辑(英文版)》1990,(7)
An ab initio calculation of the hydrogen bond complex (HF)_2 is given with the 6-311 G~(**) basis set, according to which the potential surface around the balance point of the distancès and the orientations between two HF molecules is obtained. The atomic charges in the system are calculated with the PD/LSF method (potential-derived/least-square-fitting method) and then an analysis of the hydrogen bond interaction between two HF molecules is given with the (exp-6-1) potential function, by means of which it is shown that the main interaction between them is not an electro-static but a charge transfer one. The potential curve between two HF molecules is like a Morse function. 相似文献
39.
40.
The interaction of dimethyltin dichloride (Me2SnCl2) with calf thymus DNA was studied at 27 °C, pH 7.6 using various techniques including isothermal titration calorimetry (ITC) and UV-Vis, fluorescence and IR spectrophotometries. The binding isotherm and enthalpy curve for Me2SnCl2-DNA interaction was a biphasic transition process. This was determined by the analysis of the binding data with the Hill equation. The first phase of the enthalpy curve (exothermic process) was consistent with the first set of binding site, the second phase (endothermic process, less exothermicity) was consistent with second set of binding site from the cited interactions. Our results showed that the first set of binding sites is occupied by one mole of ligand bound per near 1 base pair of DNA. The DNA-ethidium bromide (EB) complex, in the presence of Me2SnCl2, caused the quenching of the fluorescence emission. The Scatchard plots illustrated a non-intercalating manner for such quenching. The DNA-EB complex results indicated that the binding of Me2SnCl2 is with the phosphate groups of DNA at low ligand concentrations (<9 mM). This was confirmed with the IR spectrophotometric spectra. However, the binding at higher ligand concentrations (>9 mM) was with the base groups of DNA. Therefore, these results suggest that the Me2SnCl2 binding to DNA at low concentrations occurs through an outside interaction by an exothermic process. However, the partial unfolding of the DNA caused at higher concentrations of Me2SnCl2 is through an endothermic process involving interactions with the base groups. 相似文献