全文获取类型
收费全文 | 2311篇 |
免费 | 147篇 |
国内免费 | 14篇 |
专业分类
化学 | 1804篇 |
晶体学 | 28篇 |
力学 | 116篇 |
数学 | 86篇 |
物理学 | 438篇 |
出版年
2024年 | 3篇 |
2023年 | 24篇 |
2022年 | 48篇 |
2021年 | 54篇 |
2020年 | 46篇 |
2019年 | 55篇 |
2018年 | 32篇 |
2017年 | 35篇 |
2016年 | 97篇 |
2015年 | 103篇 |
2014年 | 104篇 |
2013年 | 159篇 |
2012年 | 201篇 |
2011年 | 214篇 |
2010年 | 134篇 |
2009年 | 113篇 |
2008年 | 165篇 |
2007年 | 134篇 |
2006年 | 131篇 |
2005年 | 126篇 |
2004年 | 99篇 |
2003年 | 85篇 |
2002年 | 102篇 |
2001年 | 43篇 |
2000年 | 38篇 |
1999年 | 28篇 |
1998年 | 11篇 |
1997年 | 15篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有2472条查询结果,搜索用时 15 毫秒
61.
Evaluation of stage acoustics in Seoul Arts Center Concert Hall by measuring stage support 总被引:1,自引:0,他引:1
Stage acoustics is an important characteristic for concert halls, both for the acoustic quality on stage and for the audience. However, relatively little research has been conducted into the question. This study was based on the investigation of an actual concert hall stage, that of the Seoul Arts Center Concert Hall in Korea. The stage acoustics was evaluated in the actual hall, and with two models: a 1:25 scale model and a computer model. The study was based on the stage support parameter ST1 proposed by Gade as a measure of support for individual performers [Acustica 65, 193-203 (1989)]. The variation of support was measured on the empty stage of the actual hall and in the two models. The effect of musicians on stage, the effect of moving the orchestra, the effect of ceiling height and of stage-wall profile were also investigated. Conclusions are drawn both relating to the Seoul Concert Hall stage and stages in general. 相似文献
62.
63.
We investigated pretilt angle generation and liquid crystal (LC) alignment by ultraviolet exposure during the imidization of polyimide (PI). The generated pretilt angle of a nematic (N) LC using an in situ photo-alignment method is smaller than that using a conventional photo-alignment method on a surface of PI having side chains. The NLC pretilt angles using an in situ photo-alignment method injected at isotropic phase increased with annealing were observed. 相似文献
64.
65.
We propose a new electric field-induced micro/nanocasting method to replicate soft patterns using micro/nanocasting techniques without pressure. The process uses an alternating current (AC) electrical field and rotation of one electrode, generating a dynamic electrical field that induces electrokinetic flow motion in a dielectric solution (polydimethylsilane, PDMS). We used a lotus leaf as a replication template and characterised the PDMS flow motion to observe the effects of various process parameters (e.g., electrical field strength, rotation speed of an electrode, and electrode shape). The unstable flow motion was significantly dependent on the processing parameters, especially the rotation speed of the electrode. Using the optimised processing conditions, the replication efficiency was about 88%. We believe that this method has potential for fabricating soft micro/nanosized structures. 相似文献
66.
Light intensity and image visualization of GDI injector sprays according to nozzle hole arrangements
The light intensity measurement and image visualization of multi-hole injection spray due to different hole arrangements and hole numbers were investigated. The light intensities and behavior characteristics of the GDI spray were analyzed through the axial and diagonal spray penetration, cone angle, and spray area from the spray images by using the image visualization system and image analysis system. The atomization performance of GDI injectors was analyzed by the local and overall Sauter mean diameter (SMD) measurement. 相似文献
67.
68.
Park Hye Min Kim Jeong Ho Kim Young Seok Kang Sung Won Oh Dae Min Lee Un Jang Kim Do Hyung Joo Koan Sik 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):1051-1057
Journal of Radioanalytical and Nuclear Chemistry - An in situ detector for radiological assessments of strontium-90 (90Sr) in river and lake water is developed, based on a CaF2(Eu) scintillator,... 相似文献
69.
Synthesis of Cationic Dumbbell-shaped Fullerene Nanostructures as Potential Photodynamic Sensitizers
A design of novel hydrophilic tetracationic dumbbell-shaped [60]fullerene nanostructures was made by balancing the hydrophilicity and hydrophobicity characteristics of the fullerene adduct for their potential application as photodynamic sensitizers in the PDT treatment. A sequential protection-deprotection reaction pathway was applied for the functional differentiation between primary and secondary amine moieties of pentaethylene hexamine. Synthesis of the target molecule involves two key steps of unsymmetrical esterification and amidation of malonic acid and subsequent fullerenation. The synthetic strategy was accomplished using mild reaction conditions in the intermediate molecule preparation and led a moderate overall product yield. 相似文献
70.
Three urea derivatives of anthraquinone were synthesized and they showed a high selectivity for dihydrogen phosphate ions. 相似文献