全文获取类型
收费全文 | 2833篇 |
免费 | 311篇 |
国内免费 | 219篇 |
专业分类
化学 | 905篇 |
晶体学 | 20篇 |
力学 | 321篇 |
综合类 | 28篇 |
数学 | 597篇 |
物理学 | 1492篇 |
出版年
2023年 | 14篇 |
2022年 | 37篇 |
2021年 | 49篇 |
2020年 | 68篇 |
2019年 | 65篇 |
2018年 | 42篇 |
2017年 | 91篇 |
2016年 | 104篇 |
2015年 | 87篇 |
2014年 | 157篇 |
2013年 | 223篇 |
2012年 | 151篇 |
2011年 | 201篇 |
2010年 | 156篇 |
2009年 | 196篇 |
2008年 | 209篇 |
2007年 | 164篇 |
2006年 | 168篇 |
2005年 | 142篇 |
2004年 | 100篇 |
2003年 | 94篇 |
2002年 | 96篇 |
2001年 | 97篇 |
2000年 | 61篇 |
1999年 | 64篇 |
1998年 | 68篇 |
1997年 | 62篇 |
1996年 | 62篇 |
1995年 | 40篇 |
1994年 | 39篇 |
1993年 | 30篇 |
1992年 | 33篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 25篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1957年 | 1篇 |
排序方式: 共有3363条查询结果,搜索用时 15 毫秒
1.
Prof. Dr. Peter Hess 《Chemphyschem》2022,23(6):e202100880
In the periodic table the position of each atom follows the ‘aufbau’ principle of the individual electron shells. The resulting intrinsic periodicity of atomic properties determines the overall behavior of atoms in two-dimensional (2D) bonding and structure formation. Insight into the type and strength of bonding is the key in the discovery of innovative 2D materials. The primary features of 2D bonding and the ensuing monolayer structures of the main-group II–VI elements result from the number of valence electrons and the change of atom size, which determine the type of hybridization. The results reveal the tight connection between strength of bonding and bond length in 2D networks. The predictive power of the periodic table reveals general rules of bonding, the bonding-structure relationship, and allows an assessment of published data of 2D materials. 相似文献
2.
《Arabian Journal of Chemistry》2022,15(12):104314
A single bubble absorption column was used to examine the effect of hydrodynamic on carbon dioxide (CO2) and hydrogen sulfide (H2S) absorption in pure water and water-based nanofluids dispersed with neat, and OH and NH2 functionalized multiwall carbon nanotubes (MWCNTs). Sodium dodecyl sulfate (SDS) was used as a surfactant and stabilizer. The maximum absorption of CO2 and H2S were found to be 0.0038 mmol/m2·s and 0.056 mmol/m2·s using NH2-MWCNTs /nanofluid with 0.5 wt% content, respectively. The diffusion coefficients of gases into the nanofluids were computed by using an equation attained based on Dankwert’s theory. A last, an empirical correlation was proposed to determine the Sherwood number for the absorption of the aforementioned gases into the nanofluids. 相似文献
3.
在EAST装置上安装了X模极化W波段多道相关反射仪,用于测量等离子体芯部密度涨落。该诊断利用低损耗(<3dB)多工器将4个不同频率(79.2GHz,85.2GHz,91.8GHz和96GHz)的微波耦合在一起,通过同一个天线发射。反射波由两个极向分离(~5cm)的天线接收,通过下变频技术实现外差测量。通过对两个极向天线接收的信号进行相关分析,获得芯部湍流垂直速度。对2018年低约束模式(L模)放电进行分析发现,在电子回旋共振加热(ECRH)等离子体中,芯部湍流垂直速度在电子逆磁漂移方向。而在注入同向中性束(co-NBI)后,芯部湍流垂直速度变为离子逆磁漂移方向。 相似文献
4.
The possibility of realizing SASE Free Election Laser in x-ray waveband with EM-wave wiggler is studied in this paper. SASE effect including saturation length, saturation power and nonlinear process is explored through a 3-D simulation code. A utilization of seed light from laser plasma x-ray is also analyzed, which demonstrates the feature of shortening the interaction length for saturation. The results show that sizeable output power of x-ray laser would be generated with a middle energy electron beam. 相似文献
5.
6.
Summary Experiments and simulations prove that correlation chromatography can greatly reduce the disadvantage of a non-linear response of the chromatographic column. A factor that has been accepted as being an important source of error in correlation or multiplex chromatography, has been shown not to be. Separations affected, improve dramatically when correlation chromatography is used, and a substantial amount of correlation noise only arises when there is a large difference in separation between a conventional chromatogram and a correlogram.A model has been developed for simulating these nonlinearities. It is shown that, especially for correlation chromatography, the simulation results match the practical measurements very well. 相似文献
7.
8.
9.
During the course of our investigation of the electron transfer properties of some redox species through highly hydrophobic
long chain alkanethiol molecules on gold in aqueous and non-aqueous solvents, we obtained some intriguing results such as
unusually low interfacial capacitance, very high values of impedance and film resistance, all of which pointed to the possible
existence of a nanometer size interfacial gap between the hydrophobic monolayer and aqueous electrolyte. We explain this phenomenon
by a model for the alkanethiol monolayer—aqueous electrolyte interface, in which the extremely hydrophobic alkanethiol film
repels water molecules adjacent to it and in the process creates a shield between the monolayer film and water. This effectively
increases the overall thickness of the dielectric layer that is manifested as an abnormally low value of interfacial capacitance.
This behaviour is very much akin to the ‘drying transition’ proposed by Lum, Chandler and Weeks in their theory of length
scale dependent hydrophobicity. For small hydrophobic units consisting of apolar solutes, the water molecules can reorganize
around them without sacrificing their hydrogen bonds. Since for an extended hydrophobic unit, the existence of hydrogen bonded
water structure close to it is geometrically unfavourable, there is a net depletion of water molecules in the vicinity leading
to the possible creation of a hydrophobic interfacial gap. 相似文献
10.
Electron beam induced quantitative X-ray mapping has become a very useful characterisation tool for determining the elemental
distribution in materials, whether using energy dispersive spectroscopy or wavelength dispersive spectroscopy. The X-ray intensity
distributions of the elements from an X-ray map allow us to generate two dimensional and ternary scatter diagrams thus converting
spatial information into concentration dimensions, which is an important tool for displaying the spatial relationships of
elements or correlated elements (phases) in materials. To best understand how to use this tool, we need to understand the
production and features of the scatter diagram. The type of clustering observed in the scatter diagram, whether oval, linear
or spherical, can give the major and trace element distributions within phases as well as qualitative and quantitative phase
information. This paper demonstrates the generation of scatter diagrams, properties of scatter diagrams, interpretation of
scatter diagrams and the advantages of scatter diagrams through the use of examples. 相似文献