全文获取类型
收费全文 | 18955篇 |
免费 | 2661篇 |
国内免费 | 2164篇 |
专业分类
化学 | 14402篇 |
晶体学 | 295篇 |
力学 | 988篇 |
综合类 | 187篇 |
数学 | 1957篇 |
物理学 | 5951篇 |
出版年
2024年 | 25篇 |
2023年 | 263篇 |
2022年 | 464篇 |
2021年 | 563篇 |
2020年 | 642篇 |
2019年 | 654篇 |
2018年 | 508篇 |
2017年 | 508篇 |
2016年 | 833篇 |
2015年 | 797篇 |
2014年 | 975篇 |
2013年 | 1367篇 |
2012年 | 1641篇 |
2011年 | 1722篇 |
2010年 | 1232篇 |
2009年 | 1056篇 |
2008年 | 1265篇 |
2007年 | 1042篇 |
2006年 | 1055篇 |
2005年 | 1004篇 |
2004年 | 795篇 |
2003年 | 689篇 |
2002年 | 769篇 |
2001年 | 512篇 |
2000年 | 460篇 |
1999年 | 409篇 |
1998年 | 300篇 |
1997年 | 282篇 |
1996年 | 267篇 |
1995年 | 249篇 |
1994年 | 199篇 |
1993年 | 179篇 |
1992年 | 166篇 |
1991年 | 145篇 |
1990年 | 132篇 |
1989年 | 105篇 |
1988年 | 89篇 |
1987年 | 63篇 |
1986年 | 69篇 |
1985年 | 66篇 |
1984年 | 38篇 |
1983年 | 35篇 |
1982年 | 26篇 |
1981年 | 30篇 |
1980年 | 16篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1975年 | 10篇 |
1974年 | 9篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
81.
82.
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
83.
84.
液态泡沫结构及其稳定性 总被引:2,自引:0,他引:2
液态泡沫由大量气泡密集堆积在少量的表面活性剂溶液中形成,是具有高度自组织结构的典型的软物质.文章从泡沫物理学角度简要介绍了液态泡沫的结构特征和稳定性方面的研究. 相似文献
85.
Cai-yun Jin Cao-zong Cheng Yong-tao Jin Jing Li 《应用数学学报(英文版)》2006,22(4):607-614
Two two-function minimax theorems are proved.The concavity-convexity conditions of the twofunctions involve strictly monotone transformations and mixing of the values of the two functions,and aredescribed by the inequalities as upward and weakly downward conditions. 相似文献
86.
87.
Seok-Soo Yoon N.A. Buznikov Lan Jin Chong-Oh Kim CheolGi Kim 《Journal of magnetism and magnetic materials》2006
The off-diagonal magnetoimpedance in field-annealed CoFeSiB amorphous ribbons was measured using a pick-up coil wound around the sample. One side of a ribbon was etched in hydrofluoric acid solution during various times in order to change the thickness of the surface crystalline layer appearing after annealing. The asymmetric two-peak field dependence of the off-diagonal impedance was observed for all samples. The evolution of the off-diagonal magnetoimpedance with the change in the ribbon thickness is analyzed. 相似文献
88.
89.
A fully coupled formulation combining reactive transport and an existing thermo-hydro-mechanical (THM) code is presented.
Special attention has been given to phenomena likely to be encountered in clay barriers used as part of containment systems
of nuclear waste. The types of processes considered include hydrolysis, complex formation, oxidation/reduction reactions,
acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetically-controlled and equilibrium-controlled
reactions have been incorporated. The total analytical concentrations (including precipitated minerals) are adopted as basic
transport variables and chemical equilibrium is achieved by minimizing Gibbs Free Energy. The formulation has been incorporated
in a general purpose computer code capable of performing numerical analysis of engineering problems. A validation exercise
concerning a laboratory experiment involving the heating and hydration of an expansive compacted clay is described. 相似文献
90.
海藻酸钠/大豆蛋白共混凝胶微球的结构 总被引:4,自引:1,他引:3
利用钙离子交联海藻酸钠/大豆分离蛋白共混溶液,制得海藻酸钠/大豆分离蛋共混凝胶微球.结果表明,海藻酸钠和大豆分离蛋白质量配比的不同以及各组分间相互作用的变化,微球呈现不同的微观结构.将微球干燥后置于水中溶胀,微球的尺寸无法回复到干燥前的尺寸,这是由于真空干燥处理使水分子挥发,促进微球内组分间形成了强的氢键作用所致.此外,用碱处理该共混微球,发现由于大豆分离蛋白溶解以及部分钙离子被置换析出,微球塌陷且内部形成了大孔. 相似文献