全文获取类型
收费全文 | 5337篇 |
免费 | 913篇 |
国内免费 | 764篇 |
专业分类
化学 | 4007篇 |
晶体学 | 68篇 |
力学 | 426篇 |
综合类 | 66篇 |
数学 | 545篇 |
物理学 | 1902篇 |
出版年
2024年 | 21篇 |
2023年 | 112篇 |
2022年 | 205篇 |
2021年 | 227篇 |
2020年 | 275篇 |
2019年 | 238篇 |
2018年 | 203篇 |
2017年 | 211篇 |
2016年 | 268篇 |
2015年 | 298篇 |
2014年 | 354篇 |
2013年 | 414篇 |
2012年 | 502篇 |
2011年 | 509篇 |
2010年 | 349篇 |
2009年 | 353篇 |
2008年 | 321篇 |
2007年 | 262篇 |
2006年 | 233篇 |
2005年 | 217篇 |
2004年 | 198篇 |
2003年 | 162篇 |
2002年 | 169篇 |
2001年 | 174篇 |
2000年 | 105篇 |
1999年 | 109篇 |
1998年 | 89篇 |
1997年 | 66篇 |
1996年 | 85篇 |
1995年 | 47篇 |
1994年 | 63篇 |
1993年 | 34篇 |
1992年 | 23篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1975年 | 1篇 |
排序方式: 共有7014条查询结果,搜索用时 8 毫秒
41.
42.
43.
Guimaraes Giulia A. A. Lacerda Janiny N. Xing Yutao Ponzio Eduardo A. Pacheco Wagner F. Semaan Felipe S. Dornellas Rafael M. 《Journal of Solid State Electrochemistry》2020,24(8):1769-1779
Journal of Solid State Electrochemistry - This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by... 相似文献
44.
Dandan Wang Jinghai Yang Guozhong Xing Lili Yang Ming Gao Tom Wu 《Journal of luminescence》2009,129(9):996-22735
Single-crystalline ZnO nanowires (NWs) were synthesized by a facile vapor transport method. The good orientation and high crystal quality were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) measurements. Excitation-power-dependence photoluminescence spectra of ZnO NWs show that the UV emission displayed an evident blueshift with increasing excitation power and the corresponding energy shift might be as large as 10 meV. This anomalous phenomenon correlates to the band bending level caused by the surface built-in electric field due to the existence of substantial oxygen vacancies. By increasing the excitation power, the enhanced neutralization effect near the surface will reduce the built-in electric field and lead to a reduction of band bending which triggers the blueshift of the UV emission. 相似文献
45.
This paper deals with the exact boundary controllability and the exact boundary synchronization for a 1-D system of wave equations coupled with velocities. These problems can not be solved directly by the usual HUM method for wave equations, however, by transforming the system into a first order hyperbolic system, the HUM method for 1-D first order hyperbolic systems, established by Li-Lu(2022) and Lu-Li(2022), can be applied to get the corresponding results. 相似文献
46.
本文对 Jordan标准形定理给出了一种使用初等变换的证明 ,直观意义明显、易于理解 ,可用于线性代数教学 . 相似文献
47.
设计了一款长度为265 mm的飞秒条纹管。采用短磁聚焦透镜和行波偏转板,并将行波偏转板置于磁透镜之前以提高偏转灵敏度。采用蒙特卡罗方法对阴极表面理想点和阴极狭缝发射的光电子初始参量进行了模拟抽样,用CST软件的Particle Tracking模块模拟跟踪了光电子的运行轨迹,统计分析了光电子在最佳像面上的位置分布和渡越时间,给出了光电子在最佳像面上的点扩展函数和调制传递函数。计算结果显示,所设计的条纹管阴极有效尺寸达到6 mm,放大率为2.4~2.5,动态空间分辨力大于55 lp/mm。经保守估算,条纹管的时间分辨力有望达到245 fs。 相似文献
48.
49.
Zhenkun Lei Hai Yun Yanru Zhao Yongming Xing Xuemin Pan 《Optics and Lasers in Engineering》2009,47(6):701-707
An improved six-step phase-shifting method is proposed for calculating full-field shear stress based on a four-step color phase-shifting method in digital photoelasticity. The method was verified using a disk under diametral compression and then applied to an aluminum alloy/epoxy joint for studying the shear transfer behavior. Experimental results revealed that the isochromatic fringe order and shear stress at the bonding interface are distributed continuously and increased with compression. In particular, an antisymmetric thermal residual shear stress appears at the bonding interface, because of the difference in the thermal expansion coefficients of Al and the resin. This indicates that the thermal residual shear stress at the bonding interface is self-balanced and reaches a peak at the edges of the bonding interface. The load transfer is realized by the shear band from the bonding interface to the bottom support. Basically, the bonding interfacial shear stress is balanced with the load. 相似文献
50.
Dake Hu Tianqi Zhao Xiaofan Ping Husong Zheng Lei Xing Xiaozhi Liu Jingying Zheng Lifei Sun Lin Gu Chenggang Tao Dong Wang Liying Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7051-7055
Two‐dimensional (2D) PtSe2 shows the most prominent layer‐dependent electrical properties among various 2D materials and high catalytic activity for hydrogen evolution reaction (HER), and therefore, it is an ideal material for exploring the structure–activity correlations in 2D systems. Here, starting with the synthesis of single‐crystalline 2D PtSe2 with a controlled number of layers and probing the HER catalytic activity of individual flakes in micro electrochemical cells, we investigated the layer‐dependent HER catalytic activity of 2D PtSe2 from both theoretical and experimental perspectives. We clearly demonstrated how the number of layers affects the number of active sites, the electronic structures, and electrical properties of 2D PtSe2 flakes and thus alters their catalytic performance for HER. Our results also highlight the importance of efficient electron transfer in achieving optimum activity for ultrathin electrocatalysts. Our studies greatly enrich our understanding of the structure–activity correlations for 2D catalysts and provide new insight for the design and synthesis of ultrathin catalysts with high activity. 相似文献