全文获取类型
收费全文 | 125654篇 |
免费 | 6047篇 |
国内免费 | 5377篇 |
专业分类
化学 | 43947篇 |
晶体学 | 1194篇 |
力学 | 7943篇 |
综合类 | 296篇 |
数学 | 34619篇 |
物理学 | 24394篇 |
综合类 | 24685篇 |
出版年
2024年 | 174篇 |
2023年 | 665篇 |
2022年 | 1255篇 |
2021年 | 1348篇 |
2020年 | 1363篇 |
2019年 | 1329篇 |
2018年 | 11613篇 |
2017年 | 11563篇 |
2016年 | 7737篇 |
2015年 | 2758篇 |
2014年 | 2884篇 |
2013年 | 3255篇 |
2012年 | 7389篇 |
2011年 | 14545篇 |
2010年 | 9246篇 |
2009年 | 9358篇 |
2008年 | 10140篇 |
2007年 | 12355篇 |
2006年 | 2992篇 |
2005年 | 3617篇 |
2004年 | 3341篇 |
2003年 | 3555篇 |
2002年 | 2633篇 |
2001年 | 1628篇 |
2000年 | 1460篇 |
1999年 | 1233篇 |
1998年 | 938篇 |
1997年 | 860篇 |
1996年 | 800篇 |
1995年 | 686篇 |
1994年 | 576篇 |
1993年 | 465篇 |
1992年 | 365篇 |
1991年 | 379篇 |
1990年 | 317篇 |
1989年 | 278篇 |
1988年 | 244篇 |
1987年 | 187篇 |
1986年 | 163篇 |
1985年 | 105篇 |
1984年 | 65篇 |
1983年 | 56篇 |
1982年 | 64篇 |
1981年 | 44篇 |
1980年 | 55篇 |
1979年 | 52篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献
3.
采用变分方法和临界点理论研究一个时标轴上二阶Dirichlet边值问题弱解的存在性. 相似文献
4.
The effects of PEA on the γ-phase PVDF crystal structure and the crystallization of PEA within the pre-existing γ-phase PVDF spherulites have been investigated by optical microscopy(OM), infrared spectroscopy(IR) and scanning electron microscopy(SEM). The results demonstrate that the γ-phase PVDF spherulites consist of the lamellae exhibiting a highly curved scroll-like morphology and develop preferentially in PEA-rich blend. With increasing PEA concentration, the scroll diameter increases and the scrolls are better separated from each other. PEA crystallizes first in the interspherulitic region and transcrystalline layer develops. Subsequently, the transcrystalline layer of PEA continues to grow within the γ-phase PVDF spherulites, e.g., in the region between the scrolls, until impinging on other PEA transcrystalline layers or spherulites. The crystallization kinetics results indicate that the growth rate of PEA crystals in the intraspherulitic region of γ-phase PVDF shows a positive correlation with content of PEA, but a negative one with the crystallization temperature of γ-phase PVDF. 相似文献
5.
6.
7.
8.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献
9.
树形结构在程序设计过程具有非常重要的作用,但树形结构的构建相对比较复杂。通过研究设计并实现一种从普通Java对象中建立树形结构的优化算法。 相似文献
10.
凋亡抑制蛋白(inhibitor of apoptosis proteins,IAPs)可以作为癌症诊断和治疗的靶点,在肿瘤研究方面备受关注,就凋亡抑制蛋白的结构、功能、在肿瘤中的表达与肿瘤的关系等研究进展作一综述,为凋亡抑制蛋白的研究提供信息和思路. 相似文献