全文获取类型
收费全文 | 5066篇 |
免费 | 1959篇 |
国内免费 | 2366篇 |
专业分类
化学 | 3622篇 |
晶体学 | 147篇 |
力学 | 141篇 |
综合类 | 79篇 |
数学 | 117篇 |
物理学 | 5285篇 |
出版年
2024年 | 35篇 |
2023年 | 106篇 |
2022年 | 153篇 |
2021年 | 169篇 |
2020年 | 100篇 |
2019年 | 116篇 |
2018年 | 103篇 |
2017年 | 114篇 |
2016年 | 115篇 |
2015年 | 170篇 |
2014年 | 519篇 |
2013年 | 321篇 |
2012年 | 347篇 |
2011年 | 434篇 |
2010年 | 439篇 |
2009年 | 462篇 |
2008年 | 383篇 |
2007年 | 322篇 |
2006年 | 379篇 |
2005年 | 414篇 |
2004年 | 413篇 |
2003年 | 570篇 |
2002年 | 318篇 |
2001年 | 377篇 |
2000年 | 274篇 |
1999年 | 206篇 |
1998年 | 200篇 |
1997年 | 187篇 |
1996年 | 210篇 |
1995年 | 228篇 |
1994年 | 156篇 |
1993年 | 166篇 |
1992年 | 171篇 |
1991年 | 197篇 |
1990年 | 168篇 |
1989年 | 154篇 |
1988年 | 48篇 |
1987年 | 54篇 |
1986年 | 31篇 |
1985年 | 25篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 5篇 |
1981年 | 1篇 |
排序方式: 共有9391条查询结果,搜索用时 218 毫秒
41.
对Sn-C60薄膜进行紫外可见光吸收,X-射线衍射和扫描电镜的测定结果显示,薄膜样品紫外可见光吸收的两个短波段吸收峰比纯C60薄膜的吸收峰显著下降,说明Sn-C60薄膜的电子光吸收跃迁为间接跃迁,能带中有杂质能级的存在;样品的X射线衍射峰则对应于面心立方结构;扫描电镜结果显示薄膜为纳米级颗粒组成。 相似文献
42.
X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al^9+ and Al^11+ ) charge states of the target ion (Al^10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes. 相似文献
43.
44.
研制了一台五通道ROSS-FILTER-PIN软X射线能谱仪,能谱范围为0.28—1.56keV.它由5个连续能段组成,每个能段的起止边由罗斯滤片对(ROSS-FILTERS)的L或K吸收边确定.罗斯滤片对的厚度通过优化计算得到,为了使每个通道的灵敏区外响应(即所测能段外响应)与通道总响应之比最小,在滤片对的第二滤片上镀上了一定厚度的第一滤片材料;为了缩减滤片表面积以增强低能滤片的抗冲击能力及方便滤片加工,能谱仪采用了小探测面积的PIN探测器(1mm2).借助此能谱仪,测量得到了喷气式Z箍缩(Z-pinch)等离子体辐射软X射线能谱的分布,并研究了软X射线产额随箍缩状况的变化趋势.
关键词:
Z箍缩等离子体
罗斯滤片
软X射线能谱 相似文献
45.
We have studied the interracial reactions between amorphous LaAlO3 thin films and Si substrates, using high- resolution transmission electron microscopy and x-ray photoelectron spectroscopy. It has been shown that the interracial layer between LaAlO3 film and Si substrate chemical states show that the ratio of La 4d3/2 to Al 2p is SiLaxAlyOz. The depth distributions of La, Si and Al of the interfacial layer remains unchanged with the depth compared to that of the LaAlO3 film. Moreover, the Si content, in the interracial layer gradually decreases with increasing thickness of the interracial layer. These results strongly suggest that the Al element is not deficient in the interracial layer, as previously believed, and the formation of a SiLaxAlyOz interracial layer is mainly due to the diffusion of Si from the substrate during the LaAlO3 film deposition. With the understanding of the interracial layer formation, ones can control the interface characteristics to ensure the desired performances of devices using high-k oxides as gate dielectrics. 相似文献
46.
47.
48.
实验研究了Bi-2212粉末在空气,8%O2和纯O2种处理的相组成特征,指出通过改变热处理温度和气氛可控制前驱粉中对2223成相影响较大的(Bi,Pb)-2212相,Ca2PbO4相,2201相和14:24AEC等相。 相似文献
49.
Self-assembly behaviour of amphiphilic diblock copolymer in selective solvents studied by synchrotron small-angle x-ray scattering
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The aggregation behaviour of styrene-vinyl benzoic acid (PSm-b-PVBAn) amphiphilic diblock copolymers in selective solvents with different m and n was investigated by synchrotron small-angle x-ray scattering (SAXS). We have carried out a detailed analysis of scattering intensity, dimension, shape and microstructure of the diblock copolymers of narrow distribution in water, methanol, ethanol and isopropanol selective solvents, respectively. We have found that the aggregation behaviour of the copolymer depends on the nature of the solvent and the micelle forms fiat disc objects with the ratio of radius ω=0.4. The average radius gyration Rg of the copolymer decreases as solvents change from isopropanol to ethanol and to methanol, and increases with increasing pH in aqueous solution, but decreases with the addition of COCl2 in ethanol solvent. The scattering intensity of diblock copolymer micelle follows I(h) ∝ h^-α in different selective solutions, suggesting that the PSm-b-PVBAn coils have self-similar structure behaviour or a fractal structure in the selective solvents. All of these revealed that the aggregation behaviour of the diblock copolymer changes dramatically with experimental condition in the selective solvent. The increase of mass fractal dimension (Dm) from 2.12 to 2.47 indicates that the copolymer chain changes from a swollen coil to a rather compact disc in the course of changing solvents, decreasing surface fractal dimension (Ds) from 2.98 to 2.58 indicates that the copolymer micelle change from a rather rough surface to a smooth form in the course of increasing pH in aqueous solutions, and increasing Dm and Ds from 2.29 to 2.35 and 2.70 to 2.90, respectively, indicates the shrinkage of copolymer micelle to a rather compact and rough disc form by adding COCl2 in ethanol solvents. 相似文献
50.