全文获取类型
收费全文 | 1252篇 |
免费 | 139篇 |
国内免费 | 112篇 |
专业分类
化学 | 848篇 |
晶体学 | 20篇 |
力学 | 58篇 |
综合类 | 8篇 |
数学 | 237篇 |
物理学 | 332篇 |
出版年
2023年 | 21篇 |
2022年 | 51篇 |
2021年 | 42篇 |
2020年 | 53篇 |
2019年 | 47篇 |
2018年 | 50篇 |
2017年 | 44篇 |
2016年 | 69篇 |
2015年 | 57篇 |
2014年 | 65篇 |
2013年 | 86篇 |
2012年 | 76篇 |
2011年 | 102篇 |
2010年 | 64篇 |
2009年 | 61篇 |
2008年 | 65篇 |
2007年 | 58篇 |
2006年 | 67篇 |
2005年 | 54篇 |
2004年 | 36篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 23篇 |
1999年 | 18篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 20篇 |
1995年 | 23篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有1503条查询结果,搜索用时 31 毫秒
211.
We apply the multifractal detrending moving average (MFDMA) to investigate and compare the efficiency and multifractality of 5-min high-frequency China Securities Index 300 (CSI 300). The results show that the CSI 300 market becomes closer to weak-form efficiency after the introduction of CSI 300 future. We find that the CSI 300 is featured by multifractality and there are less complexity and risk after the CSI 300 index future was introduced. With the shuffling, surrogating and removing extreme values procedures, we unveil that extreme events and fat-distribution are the main origin of multifractality. Besides, we discuss the knotting phenomena in multifractality, and find that the scaling range and the irregular fluctuations for large scales in the Fq(s) vs s plot can cause a knot. 相似文献
212.
Triet Minh Le Quan Hoang Pham Trong Duc Dang Tuan Huy Nguyen 《Journal of Computational and Applied Mathematics》2013
We consider the problem of determining the temperature u(x,t), for (x,t)∈[0,π]×[0,T) in the parabolic equation with a time-dependent coefficient. This problem is severely ill-posed, i.e., the solution (if it exists) does not depend continuously on the given data. In this paper, we use a modified method for regularizing the problem and derive an optimal stability estimation. A numerical experiment is presented for illustrating the estimate. 相似文献
213.
214.
215.
Liu Yuting Liu Kai Yin Dawei Yang Lisha Dang Yang Yang Lan Zou Qian 《Russian Journal of Organic Chemistry》2019,55(4):554-558
Russian Journal of Organic Chemistry - Three novel dendritic phenothiazine derivatives consisting of a biphenyl core, phenothiazine branching units, and terminal 3,7-di-tert-butylphenothiazine... 相似文献
216.
217.
Thanh Nga Pham Huu Dien Pham Dinh Kim Dang Thi Thuy Duong Thi Phuong Quynh Le Quang Duong Nguyen 《Natural product research》2019,33(9):1345-1348
Four thymol derivatives and two phenolic compounds were isolated from the aerial parts of Eupatorium fortunei. The new structures were elucidated to be 7,8,9-trihydroxythymol (1), and 8,10-didehydro-7,9-dihydroxythymol (2) by means of MS and NMR analysis. The known compounds were identified as 8,9,10-trihydroxythymol (3), 10-acetoxy-8,9-dihydroxythymol (4), o-coumaric acid (5) and 4-(2-hydroxyethyl)benzaldehyde (6). Compound 3 showed strongest inhibitory effect on the growth of Microcystis aeruginosa in comparison with CuSO4. 相似文献
218.
Kasprzak J Richard M Baas A Deveaud B André R Poizat JP Dang le S 《Physical review letters》2008,100(6):067402
Second-order time correlations of polaritons have been measured across the condensation threshold in a CdTe microcavity. The onset of Bose-Einstein condensation is marked by the disappearance of photon bunching, demonstrating the transition from a thermal-like state to a coherent state. Coherence is, however, degraded with increasing polariton density, most probably as a result of self-interaction within the condensate and scatterings with noncondensed excitons and polaritons. Such behavior clearly differentiates polariton Bose condensation from photon lasing. 相似文献
219.
Dang Huyen Vu Xuan Dang Hanh Vu Bich Doan Huu Dung Nguyen Tan Phong 《Research on Chemical Intermediates》2022,48(3):1311-1311
Research on Chemical Intermediates - 相似文献
220.
Anh Ha Lan Nhan Dang Duc Frew Russell Quynh Tran Minh 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(9):3613-3621
Journal of Radioanalytical and Nuclear Chemistry - This research aimed to authenticate the geographical origin of imported fresh apples using isotopic techniques. The results show that the... 相似文献