全文获取类型
收费全文 | 3345篇 |
免费 | 1217篇 |
国内免费 | 1167篇 |
专业分类
化学 | 1862篇 |
晶体学 | 87篇 |
力学 | 383篇 |
综合类 | 100篇 |
数学 | 225篇 |
物理学 | 3072篇 |
出版年
2024年 | 25篇 |
2023年 | 89篇 |
2022年 | 89篇 |
2021年 | 123篇 |
2020年 | 68篇 |
2019年 | 101篇 |
2018年 | 83篇 |
2017年 | 116篇 |
2016年 | 114篇 |
2015年 | 133篇 |
2014年 | 378篇 |
2013年 | 191篇 |
2012年 | 195篇 |
2011年 | 237篇 |
2010年 | 274篇 |
2009年 | 309篇 |
2008年 | 302篇 |
2007年 | 259篇 |
2006年 | 299篇 |
2005年 | 277篇 |
2004年 | 285篇 |
2003年 | 284篇 |
2002年 | 213篇 |
2001年 | 206篇 |
2000年 | 166篇 |
1999年 | 125篇 |
1998年 | 114篇 |
1997年 | 96篇 |
1996年 | 94篇 |
1995年 | 84篇 |
1994年 | 84篇 |
1993年 | 60篇 |
1992年 | 67篇 |
1991年 | 53篇 |
1990年 | 38篇 |
1989年 | 52篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 8篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有5729条查询结果,搜索用时 21 毫秒
101.
102.
103.
104.
105.
106.
Haitham Mohammad Abdelaal 《中国化学快报》2014,25(4):627-629
Hollow silica microspheres(HSMSs) have been successfully fabricated via a facile hydrothermal route using D-glucose as the sacrificial template and sodium silicate powder as the silica precursor.The resulting silica hollow particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),and infrared spectroscopy(IR).The surface area was determined using the BET method.SEM and TEM images exhibited micro-sized silica hollow particles with a size of ~1.5μm. 相似文献
107.
A well-ordered and spherical LiNi0.6Co0.2Mn0.2O2 cathode material was successfully synthesized from Ni and Mn concentration-gradient precursors via co-precipitation. The crystal structure, morphology and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and charge-discharge tests. The material delivered an initial discharge capacity of 174.3 mAh/g at 180 mA/g (1 C rate) between 2.8 and 4.3 V and more than 93.1% of that was retained after 100 cycles. In addition, it also exhibited excellent rate capability, high cut-off voltage and temperature performance. 相似文献
108.
《天然气化学杂志》2014,(6):761-770
Highly coke-resisting ZrO2-decorated Ni/A1203 catalysts for CO methanation were prepared by a two-step process. The support was first loaded with NiO by impregnating method and then modified with ZrO2 by deposition-precipitation method (IM-DP). Nitrogen adsorption- desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetdc analysis, H2 temperature- programmed reduction and desorption, NH3 temperature-programmed desorption, and zeta potential analysis were employed to characterize the samples. The results revealed that, compared with the catalysts with the same composition prepared by co-impregnation (CI) and sequential impregnation (SI) methods, the Ni/A1203 catalyst prepared by IM-DP showed much enhanced catalytic performance for syngas methanation under the condition of atmospheric pressure and a high weight hourly space velocity of 120000 mL.g-1 .h-1. In a 80 h life time test under the condition of 300-600 ~C and 3.0 MPa, this catalyst showed high stability and resistance to coking, and the amount of deposited carbon was only 0.4 wt%. On the contrary, the deposited carbon over the catalyst without ZrO2 reached 1.5 wt% after a 60 h life time test. The improved catalytic performance was attributed to the selective deposition of ZrO2 nanoparticles on the surface of NiO rather than A1203, which could he well controlled via changing the electrostatic interaction in the DP procedure. This unique structure could enhance the dissociation of CO2 and generate surface oxygen intermediates, thus preventing carbon deposition on the Ni particles in syngas methanation. 相似文献
109.
110.
TiO2 decorated with partially crystallized Pd nanoparticles (Pd/TiO2-P) was successfully prepared by atmospheric-pressure dielectric barrier discharge cold plasma. The XRD and XPS analyses proved that Pd ions were reduced to partially crystallized metallic Pd nanoparticles in Pd/TiO2-P. The XPS spectra also indicated that an enhanced metal-support interaction was formed due to the existence of partially crystallized Pd nanoparticles with lower coordination number in Pd/TiO2-P. Photocatalytic activity of Pd/TiO2-P was much higher than that of TiO2 samples decorated with well crystallized Pd nanoparticles. 相似文献