全文获取类型
收费全文 | 2289篇 |
免费 | 477篇 |
国内免费 | 298篇 |
专业分类
化学 | 1565篇 |
晶体学 | 96篇 |
力学 | 177篇 |
综合类 | 24篇 |
数学 | 218篇 |
物理学 | 984篇 |
出版年
2024年 | 8篇 |
2023年 | 85篇 |
2022年 | 129篇 |
2021年 | 174篇 |
2020年 | 170篇 |
2019年 | 146篇 |
2018年 | 134篇 |
2017年 | 141篇 |
2016年 | 130篇 |
2015年 | 191篇 |
2014年 | 219篇 |
2013年 | 208篇 |
2012年 | 231篇 |
2011年 | 228篇 |
2010年 | 120篇 |
2009年 | 149篇 |
2008年 | 139篇 |
2007年 | 122篇 |
2006年 | 107篇 |
2005年 | 74篇 |
2004年 | 45篇 |
2003年 | 21篇 |
2002年 | 23篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有3064条查询结果,搜索用时 31 毫秒
51.
Shuai Zhang Xiaofeng Duan Gongqing Li Kai Liu Yongqing Huang Xiaomin Ren 《Optical and Quantum Electronics》2018,50(8):320
We report a high-reflectivity non-periodic sub-wavelength gratings (SWGs) mirror with small-angle beam-steering ability for reflect light. It presents a distinctive characteristic of flexibly controlling the width of oscillation optical field for the improved Fabry–Perot (F–P) cavity. We propose a detailed principle analysis of the improved cavity. By finding out a set of SWGs with the designed structural parameters, both high reflectivity (>?93%) and beam steering (1°) can be implemented. By setting beam-steering angle and cavity length, we can control the width of oscillation optical field in the improved cavity. Beam steering ability and property of controlling the oscillation width are numerically investigated by finite element method. Simulation results prove that cavity length and steering angle can effectively control the main width of oscillation optical field, and the width is linearly associated with the cavity length. 相似文献
52.
53.
54.
优质农产品溯源系统的引入,既能提升有效供给、缩短流通时间,又能降低流通中的数量损耗和价值损失,由此带来了双渠道供应链系统在投资、销售、定价等方面的系列决策问题。考虑制造商开辟电子渠道、从溯源系统降低流通损耗和提高质量出发,分别构建制造商主导型的双渠道供应链决策模型。通过对比分析应用前后各成员在投资、定价及销售方面的最优策略,得到相关的核心边界值。数值仿真结果表明:核心边界值主要与双重损耗的改善程度及其他参数相关,各成员及系统接受溯源系统的应用成本不同,应用成本对各渠道销量的影响程度亦不相同,但各成员调整定价的应用成本边界值是一致的。 相似文献
55.
Mathematical Notes - In this paper, we consider the nonlinear viscoelastic Kirchhoff-type equation $${u_{tt}} - M(||\nabla u||_2^2)\Delta u + \int_0^t {h(t - s)\Delta u(s)ds + a|{u_t}{|^{m -... 相似文献
56.
57.
Light propagation through the channel filter based on the two-dimensional photonic crystals with oval-rod defects is studied by the finite-difference time-domain method. In addition to the traditional size tuning, shape alteration of the defects from the usual circle to the ellipse offers a powerful approach to tune the resonant frequency of channel-drop filters based on two-dimensional photonic crystals. It is found that the resonant frequency can be flexibly adjusted only by changing the orientation angle of the oval defects. The sensitivity of the resonant frequency to the alteration of the oval rods’ rotation angle is systematically studied. Because the rotation angles of the ellipse can be continuously adjusted, so the channel drop filter based on this kind of defects with different rotation angles is more suitable to the occasion where a large number of output channel filters is need. 相似文献
58.
59.
Shao-Liang Zhang Zhao-Feng Xue Ya-Ru Gao Shuai Mao Yong-Qiang Wang 《Tetrahedron letters》2012,53(19):2436-2439
An efficient triple condensation reaction of aryl methyl ketones catalyzed by ethylenediamine and trifluoroacetic acid was reported. A broad scope of 1,3,5-triarylbenzenes was obtained in good to excellent yields. The reaction provides a novel and practical approach to access organic materials of polycyclic aromatic hydrocarbons under mild conditions. 相似文献
60.
Back Cover: Improved Electrochromic Performance of Poly(3,4‐ethylenedioxythiophene) by Incorporating a Three‐Dimensionally Ordered Macroporous Structure (Chem. Asian J. 20/2016)
下载免费PDF全文
![点击此处可从《化学:亚洲杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)