全文获取类型
收费全文 | 86711篇 |
免费 | 16490篇 |
国内免费 | 9009篇 |
专业分类
化学 | 59616篇 |
晶体学 | 877篇 |
力学 | 5606篇 |
综合类 | 512篇 |
数学 | 10054篇 |
物理学 | 35545篇 |
出版年
2024年 | 100篇 |
2023年 | 1992篇 |
2022年 | 2025篇 |
2021年 | 2883篇 |
2020年 | 3874篇 |
2019年 | 3452篇 |
2018年 | 3088篇 |
2017年 | 2748篇 |
2016年 | 4430篇 |
2015年 | 4133篇 |
2014年 | 5093篇 |
2013年 | 6541篇 |
2012年 | 8039篇 |
2011年 | 8398篇 |
2010年 | 5546篇 |
2009年 | 5379篇 |
2008年 | 5779篇 |
2007年 | 5063篇 |
2006年 | 4760篇 |
2005年 | 3819篇 |
2004年 | 2940篇 |
2003年 | 2294篇 |
2002年 | 2107篇 |
2001年 | 1815篇 |
2000年 | 1594篇 |
1999年 | 1775篇 |
1998年 | 1537篇 |
1997年 | 1525篇 |
1996年 | 1513篇 |
1995年 | 1307篇 |
1994年 | 1139篇 |
1993年 | 985篇 |
1992年 | 853篇 |
1991年 | 779篇 |
1990年 | 639篇 |
1989年 | 499篇 |
1988年 | 370篇 |
1987年 | 305篇 |
1986年 | 322篇 |
1985年 | 261篇 |
1984年 | 149篇 |
1983年 | 116篇 |
1982年 | 100篇 |
1981年 | 57篇 |
1980年 | 42篇 |
1979年 | 10篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1957年 | 31篇 |
1922年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Luo Laizhen Wang Jiamei Zhang Lin Jing Yangping 《International Journal of Theoretical Physics》2021,60(7):2642-2652
International Journal of Theoretical Physics - In this paper, we will consider the exact calculation of differential entropy of induced random state ensemble by partial tracing a subsystem over... 相似文献
102.
Guo W.-T. Peng Y.-D. Zhang Y. Zhang H. Jiang Y.-L. 《Journal of Applied Spectroscopy》2021,88(2):452-460
Journal of Applied Spectroscopy - A novel tridentate bisoxime chemosensor HL has been developed as a two-in-one platform for colorimetric recognition of Cu2+ (from blue to green), and fluorescent... 相似文献
103.
Towards Fabrication of Atomic Dopant Wires via Monolayer Doping Patterned by Resist-Free Lithography 下载免费PDF全文
Fabrication of atomic dopant wires at large scale is challenging.We explored the feasibility to fabricate atomic dopant wires by nano-patterning self-assembled dopant carrying molecular monolayers via a resist-free lithographic approach.The resist-free lithography is to use electron beam exposure to decompose hydrocarbon contaminants in vacuum chamber into amorphous carbon that serves as an etching mask for nanopatterning the phosphorus-bearing monolayers.Dopant wires were fabricated in silicon by patterning diethyl vinylphosphonate monolayers into lines with a width ranging from 1 μm down to 8 nm.The dopants were subsequently driven into silicon to form dopant wires by rapid thermal annealing.Electrical measurements show a linear correlation between wire width and conductance,indicating the success of the monolayer patterning process at nanoscale.The dopant wires can be potentially scaled down to atomic scale if the dopant thermal diffusion can be mitigated. 相似文献
104.
We reported a chalcogenide glass-based rib waveguide fabricated using photolithography and dry etching method. A commercial software(COMSOL Multiphysics) was used to optimize the waveguide structure and the distribution of the fundamental modes in the waveguide based on the complete vector finite component. We further employed thermal annealing to optimize the surface and sidewalls of the rib waveguides. It was found that the optimal annealing temperature for Ge As Se S films is 220℃, and the roughness of the films could be significantly reduced by annealing. The zero-dispersion wavelength(ZDW) could be shifted to a short wavelength around ~2.1 μm via waveguide structural optimization, which promotes supercontinuum generation with a short wavelength pump laser source. The insertion loss of the waveguides with cross-sectional areas of 4.0 μm×3.5 μm and 6.0 μm×3.5 μm was measured using lens fiber and the cut-back method. The propagation loss of the 220℃ annealed waveguides could be as low as 1.9 d B/cm at 1550 nm. 相似文献
105.
We propose a lumped element Josephson parametric amplifier with vacuum-gap-based capacitor.The capacitor is made of quasi-floating aluminum pad and on-chip ground.We take a fabrication process compatible with air-bridge technology,which makes our design adaptable for future on-chip integrated quantum computing system.Further engineering the input impedance,we obtain a gain above 20 dB over 162-MHz bandwidth,along with a quasi quantum-limit noise performance.This work should facilitate the development of quantum information processing and integrated superconducting circuit design. 相似文献
106.
Theoretical and Mathematical Physics - By introducing shift relations satisfied by a matrix $$\boldsymbol{r}$$ , we propose a generalized Cauchy matrix scheme and construct a discrete second-order... 相似文献
107.
108.
Acta Mathematicae Applicatae Sinica, English Series - This paper proposes a method for modelling volatilities (conditional covariance matrices) of high dimensional dynamic data. We combine the... 相似文献
109.
Xu Yifan Zhang Hehe Ding Tangjing Tian Ruiqi Sun Dongmei Wang Ming-Sheng Zhou Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume... 相似文献
110.
当前锂离子动力电池电化学模型存在模型复杂、建模难度大、计算效率低、老化评估效果差的问题,本文提出一种考虑电池衰退老化的机理模型(ADME).本文首先通过有限差分法对伪二维(P2D)电化学模型进行离散降阶处理,得到简化伪二维(SP2D)模型.在SP2D模型的基础上,基于阴阳两极发生的副反应导致的衰退老化现象,提出一种考虑电池衰退老化的机理模型.其次,使用多变量偏差补偿最小二乘法实现模型参数辨识.最后通过动力电池衰退老化性能循环实验,对比分析了恒流、脉冲工况下SP2D模型和ADME模型的终端电压输出.结果表明:ADME模型较为简单、计算效率和估算精度高,可以有效评估电池容量老化衰退,得到理想的锂离子动力电池外特性曲线. 相似文献