全文获取类型
收费全文 | 3722篇 |
免费 | 117篇 |
国内免费 | 20篇 |
专业分类
化学 | 1387篇 |
晶体学 | 34篇 |
力学 | 406篇 |
综合类 | 1篇 |
数学 | 686篇 |
物理学 | 1345篇 |
出版年
2024年 | 8篇 |
2023年 | 63篇 |
2022年 | 94篇 |
2021年 | 218篇 |
2020年 | 204篇 |
2019年 | 148篇 |
2018年 | 158篇 |
2017年 | 146篇 |
2016年 | 146篇 |
2015年 | 139篇 |
2014年 | 153篇 |
2013年 | 245篇 |
2012年 | 243篇 |
2011年 | 288篇 |
2010年 | 282篇 |
2009年 | 255篇 |
2008年 | 176篇 |
2007年 | 132篇 |
2006年 | 112篇 |
2005年 | 91篇 |
2004年 | 42篇 |
2003年 | 52篇 |
2002年 | 45篇 |
2001年 | 66篇 |
2000年 | 36篇 |
1999年 | 74篇 |
1998年 | 8篇 |
1997年 | 20篇 |
1996年 | 13篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 20篇 |
1992年 | 19篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有3859条查询结果,搜索用时 31 毫秒
1.
2.
Cobalt oxide (Co3O4) modified anatase titanium dioxide nanotubes (ATNTs) have been investigated for the electrochemical sensing of hydrogen peroxide (H2O2). ATNTs have been synthesized by a two-step anodization process. ATNTs were then modified with Co3O4 employing chemical bath deposition method. The structure and morphology of ATNTs and their modification with Co3O4 has been confirmed by X-ray diffraction by scanning electron microscopy. H2O2 sensing has been studied in 0.1 M PBS solution, by cyclic voltammetry and amperometry. Variation in the peak positions and current densities was observed with addition of H2O2 for Co3O4 modified ATNTs. Sensitivity and limit of detection improved with modification of ATNTs with Co3O4 with precursor concentration up to 0.8 M. However, at higher precursor concentrations sensitivity and limit of detection toward H2O2 deteriorated. Co3O4 Modified ATNTS using 0.8 M precursor concentration are comparatively more suitable for H2O2 sensing applications due to the optimum formation of Co3O4/ATNTs heterojunctions. 相似文献
3.
Effect of induced magnetic field is critical as a result of much controlled and focused on liquid flow is wanted in numerous modern and clinical procedures for example electromagnetic casting, drug delivery and cooling of nuclear reactors. Hence this investigation explains the behaviour of hybrid carbon nanotubes (CNTs) flow through slipped surface with induced magnetic field. Accumulation of SWCNTs (single wall) and MWCNTs (multi wall) nanomaterial with water base liquid is considered. Thermal performance is analyzed with regular heat source/sink effect. Chemical reaction and activation energy impacts are incorporated in mass equation. Solution of the similarity equations are obtained by adopting RKF45 method. Influence of flow variables are illustrated through graphs and computational values of drag force, Nusselt number and Sherwood number are presented in tables. It is noted that activation energy enhance the concentration field whereas opposite behaviour for reaction rate. Also induce magnetic field boosted with the larger values of magnetic Prandtl number. Furthermore it is observed that hybrid CNTs nanomaterial having higher rate of heating/cooling compare to singular CNTs nanomaterial. 相似文献
4.
We discuss the notion of representing the values of physical quantities by the real numbers, and its limits to describe the nature to be understood in the relation to our appreciation that the quantum theory is a better theory of natural phenomena than its classical analog. Getting from the algebra of physical observables to their values for a fixed state is, at least for classical physics, really a homomorphic map from the algebra into the real number algebra. The limitation of the latter to represent the values of quantum observables with noncommutative algebraic relation is obvious. We introduce and discuss the idea of the noncommutative values of quantum observables and its feasibility, arguing that at least in terms of the representation of such a value as an infinite set of complex numbers, the idea makes reasonable sense theoretically as well as practically. 相似文献
5.
6.
7.
To construct a class of new multiwave interaction solutions for the (3+1)-dimensional generalized Kadomtsev-Petviashvili equation, we calculate different types of interaction solutions among solitons, periodic waves and rational waves using the direct algebraic method together with the inheritance solving skill. Moreover, a new algorithm is proposed with the aid of the simplified Hirota method, the conjugated parameters assignment and long wave limit strategies, from which multiwave interaction solutions among solitons, breathers and lump waves are generated. 相似文献
8.
The localized electrostatic structures with dissipation due to ion-neutral collisions in a symmetric warm pair-ion plasma in the presence of non-Maxwellian population of electrons are studied. The analytical model for ion dynamics is based on fluid equations and the evolution equation is derived by using the reductive perturbation scheme in the form of a damped Korteweg-de Vries equation. The parameter regime relevant to space-based observations and laboratory plasmas is considered and time evolution of the propagating ion-acoustic soliton is discussed. The energetic-particles-driven properties of soliton for various spectral indices, dissipation, ion temperature, and density are illustrated with comparison to the thermal mode for Boltzmann distribution of electrons. 相似文献
9.
The present work has been focussed on the application of Projected Shell Model to study the negative parity rotational band structure up to the high spin states of the neutron-rich odd mass Terbium isotopes with neutron numbers ranging from 90 to 98. The structure evolution in these nuclei has been made on the basis of various nuclear structure properties like energy spectra, transition energies, wave functions and electromagnetic transition probabilities (B(E2) and B(M1)). Besides, the occurrence of back bending has also been reported in the present work. 相似文献
10.
Yousaf Raffia bintay Bakar Shahzad Abu Mazhar Muhammad Mansoor Muhammad Adil Iqbal Mudassir 《Russian Journal of Applied Chemistry》2022,95(1):37-45
Russian Journal of Applied Chemistry - Owing to high stability, metal oxide-based ceramic thin films are of great interest for photocatalytic oxidation of water. Therefore, the current research is... 相似文献