全文获取类型
收费全文 | 169628篇 |
免费 | 20235篇 |
国内免费 | 15590篇 |
专业分类
化学 | 77963篇 |
晶体学 | 1226篇 |
力学 | 6463篇 |
综合类 | 731篇 |
数学 | 13784篇 |
物理学 | 42443篇 |
综合类 | 62843篇 |
出版年
2024年 | 703篇 |
2023年 | 2902篇 |
2022年 | 4857篇 |
2021年 | 5208篇 |
2020年 | 5206篇 |
2019年 | 4582篇 |
2018年 | 4539篇 |
2017年 | 4269篇 |
2016年 | 6121篇 |
2015年 | 6685篇 |
2014年 | 8694篇 |
2013年 | 10448篇 |
2012年 | 12196篇 |
2011年 | 12557篇 |
2010年 | 9513篇 |
2009年 | 9399篇 |
2008年 | 10221篇 |
2007年 | 9370篇 |
2006年 | 8533篇 |
2005年 | 7559篇 |
2004年 | 5854篇 |
2003年 | 5033篇 |
2002年 | 4924篇 |
2001年 | 4506篇 |
2000年 | 3923篇 |
1999年 | 5098篇 |
1998年 | 4278篇 |
1997年 | 4056篇 |
1996年 | 3924篇 |
1995年 | 3405篇 |
1994年 | 3055篇 |
1993年 | 2519篇 |
1992年 | 2204篇 |
1991年 | 2029篇 |
1990年 | 1677篇 |
1989年 | 1499篇 |
1988年 | 1170篇 |
1987年 | 815篇 |
1986年 | 610篇 |
1985年 | 374篇 |
1984年 | 228篇 |
1983年 | 167篇 |
1982年 | 136篇 |
1981年 | 83篇 |
1980年 | 63篇 |
1979年 | 29篇 |
1978年 | 26篇 |
1976年 | 27篇 |
1975年 | 25篇 |
1957年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Guo Yan Li Zhuang Wei Yuxi Zhang Xinxu Shi Kexin 《Journal of Solid State Electrochemistry》2022,26(4):1051-1065
Journal of Solid State Electrochemistry - Polyvinylpyrrolidone (PVP) and graphene (G)-modified iron oxides (Fe2O3-PVP-G) are prepared by a simple hydrothermal reaction. Their morphology and... 相似文献
82.
83.
The Ramanujan Journal - Inspired by Andrews and Merca’s recent work on the number of even parts over all partitions into distinct parts, we introduce a new kind of Beck type identities, which... 相似文献
84.
85.
Au@Cu_2O core-shell nanorods with tunable thickness of Cu_2O shell were synthesized and their linear and nonlinear optical responses were investigated. Two transverse plasmon resonance peaks were observed when the Au nanorods were coated with Cu_2O shells, which were adjusted by the Cu_2O shell thickness. The nonlinear absorption of the Au@Cu_2O nanorods is enhanced by 5 times at the longitudinal plasmon resonance wavelength compared with that of bare Au nanorods. More intriguingly, largely enhanced nonlinear refraction and suppressed nonlinear absorption at the transverse plasmon resonance wavelength were observed in the Au@Cu_2O nanorods. Our findings indicate the existence of strong local field enhancement at the interface between the Au core and the Cu_2O shell, which would provide a promising strategy in designing plasmonic nonlinear nanodevices with good nonlinear figures of merit. 相似文献
86.
Hierarchical motion planning at the acceleration level based on task priority matrix for space robot
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to... 相似文献
87.
Chi-Kwong Li Ming-Cheng Tsai Ya-Shu Wang Ngai-Ching Wong 《Journal of Mathematical Analysis and Applications》2022,505(2):125522
Let L be an additive map between (real or complex) matrix algebras sending Hermitian idempotent matrices to Hermitian idempotent matrices. We show that there are nonnegative integers with and an unitary matrix U such that We also extend this result to the (complex) von Neumann algebra setting, and provide a supplement to the Dye-Bunce-Wright Theorem asserting that every additive map of Hermitian idempotents extends to a Jordan ?-homomorphism. 相似文献
88.
Chen Fenge Li Bing Peng Xingchun 《Methodology and Computing in Applied Probability》2022,24(2):635-659
Methodology and Computing in Applied Probability - This paper is devoted to the study of an optimal investment and risk control problem for an insurer. The risky asset process and the insurance... 相似文献
89.
Jia Tian-Cong Guo Jin-Tao Wang Zhen Zhu Xiao-Shan Zhang Qian-Xin Chen Ping Yao Kun Lv Wen-Ying Liu Guo-Guang 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(3):823-829
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of... 相似文献
90.
Through molecular dynamics(MD)simulation,the dependencies of temperature,grain size and strain rate on the mechanical properties were studied.The simulation results demonstrated that the strain rate from 0.05 to 2 ns~(–1 )affected the Young’s modulus of nickel nanowires slightly,whereas the yield stress increased.The Young’s modulus decreased approximately linearly;however,the yield stress firstly increased and subsequently dropped as the temperature increased.The Young’s modulus and yield stress increased as the mean grain size increased from 2.66 to6.72 nm.Moreover,certain efforts have been made in the microstructure evolution with mechanical properties association under uniaxial tension.Certain phenomena such as the formation of twin structures,which were found in nanowires with larger grain size at higher strain rate and lower temperature,as well as the movement of grain boundaries and dislocation,were detected and discussed in detail.The results demonstrated that the plastic deformation was mainly accommodated by the motion of grain boundaries for smaller grain size.However,for larger grain size,the formations of stacking faults and twins were the main mechanisms of plastic deformation in the polycrystalline nickel nanowire. 相似文献