全文获取类型
收费全文 | 247218篇 |
免费 | 3386篇 |
国内免费 | 660篇 |
专业分类
化学 | 127620篇 |
晶体学 | 3551篇 |
力学 | 10287篇 |
综合类 | 6篇 |
数学 | 30382篇 |
物理学 | 79418篇 |
出版年
2021年 | 2050篇 |
2020年 | 2369篇 |
2019年 | 2422篇 |
2018年 | 3262篇 |
2017年 | 3146篇 |
2016年 | 4935篇 |
2015年 | 3323篇 |
2014年 | 4753篇 |
2013年 | 11465篇 |
2012年 | 9300篇 |
2011年 | 11082篇 |
2010年 | 7381篇 |
2009年 | 7063篇 |
2008年 | 10121篇 |
2007年 | 10187篇 |
2006年 | 9639篇 |
2005年 | 8606篇 |
2004年 | 7871篇 |
2003年 | 6784篇 |
2002年 | 6554篇 |
2001年 | 7154篇 |
2000年 | 5675篇 |
1999年 | 4307篇 |
1998年 | 3520篇 |
1997年 | 3468篇 |
1996年 | 3366篇 |
1995年 | 3105篇 |
1994年 | 2969篇 |
1993年 | 2929篇 |
1992年 | 3200篇 |
1991年 | 3043篇 |
1990年 | 2985篇 |
1989年 | 2762篇 |
1988年 | 2814篇 |
1987年 | 2802篇 |
1986年 | 2602篇 |
1985年 | 3449篇 |
1984年 | 3679篇 |
1983年 | 3060篇 |
1982年 | 3223篇 |
1981年 | 3209篇 |
1980年 | 3047篇 |
1979年 | 3094篇 |
1978年 | 3223篇 |
1977年 | 3172篇 |
1976年 | 3224篇 |
1975年 | 2988篇 |
1974年 | 2957篇 |
1973年 | 3104篇 |
1972年 | 1913篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Lubomír Havlk Jan Fbry Margarida Henriques Michal Duek 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(7):623-630
The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the α‐NaFeO2 structure type in agreement with the ratio of the ionic radii r3+/r+. KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S—S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S2−) and the bond‐valence sums. 相似文献
63.
This study compares the physicochemical properties of six electrolytes comprising of three salts: LiFTFSI, NaFTFSI and KFTFSI in two solvent mixtures, the binary (3EC/7EMC) and the ternary (EC/PC/3DMC). The transport properties (conductivity, viscosity) as a function of temperature and concentration were modeled using the extended Jones-Dole-Kaminsky equation, the Arrhenius model, and the Eyring theory of transition state for activated complexes. Results are discussed in terms of ionicity, solvation shell, and cross-interactions between electrolyte components. The application of the six formulated electrolytes in symmetrical activated carbon (AC)//AC supercapacitors (SCs) was characterized by cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and accelerated aging. Results revealed that the geometrical flexibility of the FTFSI anion allows it to access and diffuse easily in AC whereas its counter ions (Li+, Na+ or K+) can remain trapped in porosity. However, this drawback was partially resolved by mixing LiFTFSI and KFTFSI salts in the electrolyte. 相似文献
64.
65.
Mathematical Notes - We study the multiplicity of weak solutions to the boundary-value problem $$\begin{alignedat}{2} - M\biggl(\iint_{\mathbb R^{2N}}|u(x)-u(y)|^2 K(x-y)\,d x\,d y\biggr)\mathscr... 相似文献
66.
Optics and Spectroscopy - A cell with a submicron thickness was used to measure the broadening and shift of the D1 and D2 lines of Rb atoms by neon. The resolution of hypefine components... 相似文献
67.
68.
Periodica Mathematica Hungarica - We present a tight parametrical Hermite–Hadamard type inequality with probability measure, which yields a considerably closer upper bound for the mean value... 相似文献
69.
Mathematical Notes - It is proved that the lattice of all Fitting classes of finite groups is not distributive, and conditions under which Fitting classes satisfy the distributive and modular laws... 相似文献
70.
Kuzmenkova P. S. Gromushkin D. M. Shulzhenko I. A. Tretyakova T. D. 《Physics of Atomic Nuclei》2021,84(9):1588-1592
Physics of Atomic Nuclei - The paper presents a comparison of three neutrons identifying methods in scintillators based on ZnS with 6Li and 10B: charge integration method, pulse gradient analysis,... 相似文献