全文获取类型
收费全文 | 5832篇 |
免费 | 1082篇 |
国内免费 | 798篇 |
专业分类
化学 | 4353篇 |
晶体学 | 103篇 |
力学 | 364篇 |
综合类 | 44篇 |
数学 | 693篇 |
物理学 | 2155篇 |
出版年
2024年 | 18篇 |
2023年 | 133篇 |
2022年 | 217篇 |
2021年 | 241篇 |
2020年 | 332篇 |
2019年 | 294篇 |
2018年 | 264篇 |
2017年 | 279篇 |
2016年 | 342篇 |
2015年 | 372篇 |
2014年 | 341篇 |
2013年 | 484篇 |
2012年 | 545篇 |
2011年 | 537篇 |
2010年 | 395篇 |
2009年 | 374篇 |
2008年 | 387篇 |
2007年 | 319篇 |
2006年 | 307篇 |
2005年 | 262篇 |
2004年 | 214篇 |
2003年 | 150篇 |
2002年 | 159篇 |
2001年 | 112篇 |
2000年 | 104篇 |
1999年 | 101篇 |
1998年 | 39篇 |
1997年 | 45篇 |
1996年 | 39篇 |
1995年 | 35篇 |
1994年 | 12篇 |
1993年 | 29篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 19篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有7712条查询结果,搜索用时 947 毫秒
991.
992.
993.
Differential infrared thermography (DIT) was investigated and applied for the detection of unsteady boundary layer transition locations on a pitching airfoil and on a rotating blade under cyclic pitch. DIT is based on image intensity differences between two successively recorded infrared images. The images were recorded with a high framing rate infrared camera. A pitching NACA0012 airfoil served as the first test object. The recorded images were used in order to investigate and to further improve evaluation strategies for periodically moving boundary layer transition lines. The measurement results are compared with the results of unsteady CFD simulations based on the DLR-TAU code. DIT was then used for the first time for the optical measurement of unsteady transition locations on helicopter rotor blade models under cyclic pitch and rotation. Image de-rotation for tracking the blade was employed using a rotating mirror to increase exposure time without causing motion blur. The paper describes the challenges that occurred during the recording and evaluation of the data in detail. However, the results were found to be encouraging to further improve the method toward the measurement of unsteady boundary layer transition lines on helicopter rotor models in forward flight. 相似文献
994.
995.
Dr. Baiqi Shao Dr. Sikang Wan Chenjing Yang Dr. Jianlei Shen Dr. Yiwen Li Prof. Hongpeng You Prof. Dong Chen Prof. Chunhai Fan Prof. Kai Liu Prof. Hongjie Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18370-18374
The self-assembly of inorganic nanoparticles into well-ordered structures in the absence of solvents is generally hindered by van der Waals forces, leading to random aggregates between them. To address the problem, we functionalized rigid rare-earth (RE) nanoparticles with a layer of flexible polymers by electrostatic complexation. Consequently, an ordered and solvent-free liquid crystal (LC) state of RE nanoparticles was realized. The RE nanomaterials including nanospheres, nanorods, nanodiscs, microprisms, and nanowires all show a typical nematic LC phase with one-dimensional orientational order, while their microstructures strongly depend on the particles’ shape and size. Interestingly, the solvent-free thermotropic LCs possess an extremely wide temperature range from −40 °C to 200 °C. The intrinsic ordering and fluidity endow anisotropic luminescence properties in the system of shearing-aligned RE LCs, offering potential applications in anisotropic optical micro-devices. 相似文献
996.
997.
998.
Juanjuan Zhou Dr. Kai Huang Shaochen Lin Nan Zhang Xin Wang Dr. Yang Li Prof. Zhanjun Li Prof. Gang Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(26):e202104366
While concerns about improving recharged afterglow intensity in vivo still motivate further exploration, afterglow nanoparticles (AGNP) offer unique optical merit for autofluorescence-free biological imaging. Apart from efforts enhancing the afterglow emission properties of AGNP, improving afterglow excitation response to visible or near infrared light is important but has lacked success. Dye sensitization has been used to improve the optical response of photovoltaic nanomaterials and to enhance upconversion luminescence efficiency. This concept has recently been expanded and applied to AGNPs. As a new multifunctional nanoprobe, such dye-sensitized AGNP takes advantage of both high spatial resolution fluorescence imaging and sensitive afterglow imaging. This Concept introduces the background, the concept, mechanism, and related imaging application, as well as reviewing existing challenges and proposing future developmental directions for the dye-sensitized AGNPs. 相似文献
999.
Dr. Toshiro Takao Dr. Yuta Takahashi Masataka Kai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(29):e202200327
A dicationic triruthenium complex containing a μ3-η3-C3 ring, [(Cp*Ru)3(μ3-η3-C3MeH2−)(μ3-CH)(μ-H)]2+ ( 1 a , Cp*=η5-C5Me5), reacted with ammonia to yield a μ-amido complex, [(Cp*Ru)3(μ3-η3-CHCMeCH) (μ3-CH)(μ-NH2)]2+ ( 5 ), via N−H bond scission. Subsequent treatment with base resulted in C−N bond formation to yield a μ3-η2:η2-1-azabutadien-4-yl complex, [(Cp*Ru)3(μ3-CH)(μ3-η2:η2-NH=CH−CMe=CH−)]+ ( 6 a ). The azaruthenacyclopentadiene skeleton was alternatively synthesized by the photolysis of mono-cationic complex [(Cp*Ru)3(μ3-η3-C3RH2−)(μ3-CH)]+ ( 2 a ; R=Me, 2 b ; R=H) in the presence of ammonia. The C3 ring skeleton was broken via the electron transfer to the π*(C−C) orbital in the C3 ring, and a transiently generated unsaturated μ3-allylic species can take up ammonia, resulting in N−H bond scission followed by C−N bond formation. 相似文献
1000.
Qingqing Ma Shanlin Xu Zhaodong Zhai Kai Wang Xueli Liu Prof. Haibin Xiao Prof. Shuping Zhuo Prof. Yuying Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(39):e202200828
Peroxynitrite (ONOO−) as a major reactive oxygen species plays important roles in cellular signal transduction and homeostatic regulation. Precise detection of ONOO− in biological systems is vital for exploring its physiological and pathological function. Among numerous detection methods, fluorescence imaging technology using fluorescent probes offers some advantages, including simple operation, high sensitivity and selectivity, as well as real-time and nondestructive detection. In particular, ratiometric fluorescent probes, in which the built-in calibration of the two emission bands prevents interference from the biological environment, have been extensively employed to monitor the fluctuation of bioactive species. In this review, we will discuss small-molecule ratiometric fluorescent probes for ONOO− in live cells or in vivo, which involves chemical structures, response mechanisms, and biological applications. Moreover, the challenges and future prospects of ONOO−-responsive ratiometric fluorescent probe are also proposed. 相似文献