全文获取类型
收费全文 | 19287篇 |
免费 | 3587篇 |
国内免费 | 3745篇 |
专业分类
化学 | 17133篇 |
晶体学 | 405篇 |
力学 | 1034篇 |
综合类 | 150篇 |
数学 | 434篇 |
物理学 | 7463篇 |
出版年
2024年 | 41篇 |
2023年 | 221篇 |
2022年 | 502篇 |
2021年 | 685篇 |
2020年 | 991篇 |
2019年 | 788篇 |
2018年 | 755篇 |
2017年 | 952篇 |
2016年 | 1071篇 |
2015年 | 995篇 |
2014年 | 1195篇 |
2013年 | 1912篇 |
2012年 | 1319篇 |
2011年 | 1436篇 |
2010年 | 1077篇 |
2009年 | 1183篇 |
2008年 | 1089篇 |
2007年 | 1190篇 |
2006年 | 1085篇 |
2005年 | 989篇 |
2004年 | 878篇 |
2003年 | 791篇 |
2002年 | 708篇 |
2001年 | 630篇 |
2000年 | 589篇 |
1999年 | 524篇 |
1998年 | 456篇 |
1997年 | 424篇 |
1996年 | 384篇 |
1995年 | 316篇 |
1994年 | 299篇 |
1993年 | 233篇 |
1992年 | 208篇 |
1991年 | 135篇 |
1990年 | 97篇 |
1989年 | 89篇 |
1988年 | 99篇 |
1987年 | 56篇 |
1986年 | 51篇 |
1985年 | 31篇 |
1984年 | 28篇 |
1983年 | 9篇 |
1982年 | 25篇 |
1981年 | 25篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
104.
四溴双酚A锑铝双金属化合物的合成及其阻燃性能 总被引:1,自引:0,他引:1
以四溴双酚A(TBA)合成了在水和空气中稳定的四溴双酚A合锑铝双金属化合物(TBASA).通过IR、1HNMR和元素分析予以表征,并研究了其对聚乙烯(PE)和聚环氧乙烷(PEO)的阻燃性能.结果表明,这种分子中含有溴、锑和铝的化合物,对聚乙烯和聚环氧乙烷等高聚物材料有高的阻燃性能与消烟效果. 相似文献
105.
The dendrite growth process of transparent NaBi(WO4)2 with small prandtl and high melting point was studied by using the in-situ observation system. According to the dynamic images and detailed information, there are two kinds of restriction effect on the dendrite growth, the competition between arms and branches and the convection in the melt. The dendrite growth rate was time dependent, and the rate of arm growth reached the maximum 5.8 mm/s in the diffusive-advective region and rapidly decreased in the diffusive-convective region. The growth rate of branch had the same change trends as the arm's. Based on the EPMA-EDS data of solidification structure of quenched NaBi(WO4)2 melt, it was found that there were component differences from stoichiometric concentration in the melt near the interface during the growth process. 相似文献
106.
The dendrite growth process of transparent NaBi(WO4)2 with small prandtl and high melting point was studied by using the in-situ observation system. According to the dynamic images and detailed information, there are two kinds of restriction effect on
the dendrite growth, the competition between arms and branches and the convection in the melt. The dendrite growth rate was
time dependent, and the rate of arm growth reached the maximum 5.8 mm/s in the diffusive-advective region and rapidly decreased
in the diffusive-convective region. The growth rate of branch had the same change trends as the arm’s. Based on the EPMA-EDS
data of solidification structure of quenched NaBi(WO4)2 melt, it was found that there were component differences from stoichiometric concentration in the melt near the interface
during the growth process.
Supported by the National Natural Science Foundation of China (Grant No. 50331040) and the Innovation Funds from Shanghai
Institute of Ceramics, Chinese Academy of Sciences (Grant No. SCX0623) 相似文献
107.
N. S. Oliveira J. Dorgan J. A. P. Coutinho A. Ferreira J. L. Daridon I. M. Marrucho 《Journal of Polymer Science.Polymer Physics》2007,45(5):616-625
The sorption of carbon dioxide in glassy Poly(lactic acid) (PLA) films was studied by quartz crystal microbalance (QCM) at high pressures. Two thermal treatments, melted and quenched, were performed in PLA with two different L:D contents, 80:20 and 98:2, films and compared with a third thermal protocol, annealed, and used in a previous work. The results obtained show that for pressures higher than 2 MPa, the carbon dioxide solubility is larger in PLA 80:20 than in PLA 98:2, indicating that the L:D plays a dominant role on this property. The thermal treatments only affect the gas solubility in PLA 98:2. Sorption isotherms at temperatures 303, 313, and 323 K, below the glass transition temperature of the polymer, and pressures up to 5 MPa were measured and analyzed with three different models, the dual‐mode sorption model, the Flory–Huggins equation, and a modified dual‐mode sorption model where the Henry's law term was substituted by the Flory–Huggins equation. This last model performs especially well for CO2 in PLA 80:20, due to the convex upward curvature of the solubility isotherms for that system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 616–625, 2007 相似文献
108.
109.
Highly ordered composite nanowires with multilayer Ni/Cu and NiFe/Cu have been fabricated by pulsed electrodeposition into
nanoporous alumina membrane. The diameter of wires can be easily varied by pore size of alumina, ranging from 30 to 100 nm.
The applied potential and the duration of each potential square pulse determine the thickness of the metal layers. The nanowires
have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer
(VSM) measurements. The MFM images indicate that every ferromagnetic layer separated by Cu layer was present as single isolated
domain-like magnet. This technique has potential use in the measurement and application of magnetic nanodevices. 相似文献
110.