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1.
Zhang Lei Xu Chao Guo Yaohao Zhu Guangpu Cai Shiyu Wang Xin Jing Wenlong Sun Hai Yang Yongfei Yao Jun 《Transport in Porous Media》2021,140(3):713-725
Transport in Porous Media - Pore scale immiscible displacement is crucial in oil industry. The surface roughness of throat is an important factor affecting water–oil interface movement. In... 相似文献
2.
本文制备了三种在1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bp-eb)上接枝不同烷基链长度的热致变色材料DC8、DC12、DC16. 在365 nm激发光下,随着温度升高,它们呈现出荧光颜色的改变,这种改变来自于晶体态与无定形态之间的转变. 此外,DC16也呈现出光致变色的性质. 通过差示扫描量热法测试得到的相转变温度高于实验过程中荧光颜色改变时的温度. 因此,这种变色行为来自于光与热共同作用的结果. 乙醇可以使粉末变回起始的晶体状态,从而使荧光颜色恢复,实现热致变色行为的可逆. 本研究对理解热致变色分子的结构-性质关系,指导热致变色分子设计具有重要意义. 相似文献
3.
本文选用混杂的B3LYP密度泛函理论方法,在Lanl2dz水平上,对5,15-二(二茂铁基)-卟啉酞菁钇[Por(Fc)2]Y(Pc)的结构进行了优化,结果表明,5,15-二(二茂铁基)-卟啉酞菁钇呈现出三明治型构型,卟啉环与酞菁环呈穹型围绕在金属钇原子周围。对分子内主要的键长与键角进行了理论计算,通过频率计算,得到了5,15-二(二茂铁基)-卟啉酞菁钇[Por(Fc)2]Y(Pc)的红外光谱图,与实验所得的红外光谱图进行比对,将理论计算和实验所得的光谱主要振动峰进行了线性回归拟合,相关系数为0.992,标准偏差为16.96。理论计算与实验所获得的红外光谱图基本一致,说明本文所选用的DFT理论计算方法是可行的。通过GaussView软件对5,15-二(二茂铁基)-卟啉酞菁钇的红外谱带简正振动模式进行了指认。此外,分析讨论了5,15-二(二茂铁基)-卟啉酞菁钇[Por(Fc)2]Y(Pc)的分子静电势,确定了极大值与极小值的位置。对于研究5,15-二(二茂铁基)-卟啉酞菁钇分子的性质,提供了相应的理论基础。 相似文献
4.
Denote a semisimple Banach algebra with an identity e by A.This paper studies the Fredholm,Weyl and Browder spectral theories in a semisimple Banach algebra,and meanwhile considers the properties of the Fredholm element,the Weyl element and the Browder element.Further,for a∈A,we give the Weyl's theorem and the Browder's theorem for a,and characterize necessary and sufficient conditions that both a and f(a) satisfy the Weyl's theorem or the Browder's theorem,where f is a complex-valued function analytic on a neighborhood of σ(a).In addition,the perturbations of the Weyl's theorem and the Browder's theorem are investigated. 相似文献
5.
The ability of the radial basis function(RBF) approach to extrapolate the masses of nuclei in neutron-rich and superheavy regions is investigated in combination with the Duflo-Zuker(DZ31), Hartree–Fock-Bogoliubov(HFB27), finite-range droplet model(FRDM12) and Weizs?cker-Skyrme(WS4) mass models. It is found that when the RBF approach is employed with a simple linear basis function, different mass models have different performances in extrapolating nuclear masses in the same region, and a single mass model may have different performances when it is used to extrapolate nuclear masses in different regions. The WS4 and FRDM12 models(two macroscopic–microscopic mass models), combined with the RBF approach, may perform better when extrapolating the nuclear mass in the neutron-rich and superheavy regions. 相似文献
6.
Chinese Journal of Polymer Science - The emerging chemical recyclable polymers, such as poly(γ-butyrolactone) (PGBL) and poly((R)-3,4-trans six-membered ring-fused GBL) (P((R)-M)), provide a... 相似文献
7.
Ning Zuozhou Zhang Zhicheng Yan Qingsong Zhou Naifu Wen Linzi Peng Xichao Tang Yu Feng Pengju 《中国科学:化学(英文版)》2022,65(10):1962-1967
Science China Chemistry - A mild and practical protocol for selectively time-dependent dehydrogenative C-C coupling, as well as tandem coupling-cyclization reaction between indoles or/and other... 相似文献
8.
Haicun Yang Shuipi Cai Yu Jiang Zheng Cao Wenzhong Ma Fanghong Gong Guoliang Tao Chunlin Liu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1571-1587
The commonly used multi-center initiation methods always lead to the formation of quantities of homopolymer in the surface tailoring based on reverse atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. In this study, a monocenter redox pair constructed of silica bearing tert-butyl hydroperoxide groups and ascorbic acid (SiO2-TBHP/AsAc) was applied to substitute the commonly used initiation method of R-supported RAFT grafting polymerization. All the propagating radicals were restricted on the surface of solid particles during the whole procedure theoretically, resulting in a higher grafting efficiency of 95.1% combined with the “controllable” feature at 10 h. This redox pair was also used to initiate the reverse ATRP in miniemulsion successfully with a grafting efficiency of 86.3% at 10 h. The grafting efficiency obtained under this monocenter initiation method was significantly higher than that of the frequently reported surface modification by reverse ATRP and RAFT polymerization. In addition, the high-efficient surface tailoring was traced and confirmed by nuclear magnetic resonance, Fourier transform infrared, X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission electron microscopy, and other analysis tests. The advantage of this monocenter redox pair will open a new avenue for the potential “high-efficient” surface tailoring of various materials. 相似文献
9.
We generalize the Heisenberg star consisting of a spin-1/2 central spin and a homogeneously coupled spin bath modeled by the XXX ring [Richter J and Voigt A 1994 J. Phys. A: Math. Gen. 27 1139-1149] to the case of arbitrary central-spin size S < N/2, where N is the number of bath spins. We describe how to block-diagonalize the model based on the Bethe ansatz solution of the XXX ring, with the dimension of each block Hamiltonian ≤ 2S + 1. We obtain all the eigenenergies and explicit expressions of the sub-ground states in each l-subspace with l being the total angular momentum of the bath. Both the eigenenergies and the sub-ground states have distinct structures depending whether S ≤ l or l < S. The absolute ground-state energy and the corresponding l as functions of the intrabath coupling are numerically calculated for N = 16 and S = 1, 2, ⋯ ,7 and their behaviors are quantitatively explained in the weak and strong intrabath coupling limits. We then study the dynamics of the antiferromagnetic order within an XXX bath prepared in the Néel state. Effects of the initial state of the central spin, the value of S, and the system-bath coupling strength on the staggered magnetization dynamics are investigated. By including a Zeeman term for the central spin and the anisotropy in the intrabath coupling, we also study the polarization dynamics of the central spin for a bath prepared in the spin coherent state. Under the resonant condition and at the isotropic point of the bath, the polarization dynamics for S > 1/2 exhibit collapse-revival behaviors with fine structures. However, the collapse-revival phenomena are found to be fragile with respect to the anisotropy of the intrabath coupling. 相似文献
10.