全文获取类型
收费全文 | 1364篇 |
免费 | 42篇 |
国内免费 | 11篇 |
专业分类
化学 | 977篇 |
晶体学 | 14篇 |
力学 | 25篇 |
数学 | 218篇 |
物理学 | 183篇 |
出版年
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 28篇 |
2020年 | 13篇 |
2019年 | 35篇 |
2018年 | 28篇 |
2017年 | 18篇 |
2016年 | 32篇 |
2015年 | 35篇 |
2014年 | 42篇 |
2013年 | 68篇 |
2012年 | 88篇 |
2011年 | 89篇 |
2010年 | 62篇 |
2009年 | 58篇 |
2008年 | 107篇 |
2007年 | 78篇 |
2006年 | 66篇 |
2005年 | 89篇 |
2004年 | 72篇 |
2003年 | 51篇 |
2002年 | 56篇 |
2001年 | 25篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 14篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1915年 | 4篇 |
1913年 | 5篇 |
1889年 | 3篇 |
排序方式: 共有1417条查询结果,搜索用时 15 毫秒
1.
L. Resse L.G.S. Oliveira C.I.L. de Araujo A.R. Pereira R.L. Silva 《Physics letters. A》2019,383(14):1655-1659
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius nm and different distance d between the disks centers (from nm to nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices. 相似文献
2.
3.
Wen Zhang Hui Huang Yu Ding Margherita Gavagnin Ernesto Mollo Guido Cimino Yue‐Wei Guo 《Helvetica chimica acta》2006,89(4):813-820
Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds. 相似文献
4.
Ernesto Quesada 《Tetrahedron letters》2004,45(25):4877-4881
The first syntheses of newly isolated members of the Preussomerin family, Preussomerins K and L, are reported. Key steps include the functionalisation of a 2-arylacetal anion, one-pot Friedel-Crafts cyclisation-deprotection and reductive opening of epoxides. 相似文献
5.
The linearized stability of charged thin shell wormholes under spherically symmetric perturbations is analyzed. It is shown that the presence of a large value of charge provides stabilization to the system, in the sense that the constraints onto the equation of state are less severe than for non-charged wormholes. 相似文献
6.
7.
Vanessa de Freitas Cunha Lins Geraldo Francisco de Andrade Reis Carlos Roberto de Araujo 《Applied Surface Science》2006,253(5):2875-2884
In this work, electrochemical impedance spectroscopy and linear polarization are used in determining porosity of zinc phosphates, and of nickel and manganese modified zinc phosphates on electrogalvanized steel. The porosity of the phosphate layers ranges from 0.1% for the manganese-modified hopeite to 8% for hopeite, using the linear polarization and the electrochemical impedance spectroscopy techniques. The porosity values measured using the two techniques were in agreement. All impedance spectra of coated samples showed two steps, with two capacitive arcs and an inductive looping. 相似文献
8.
9.
B. F. Araujo H. T. Matsuda T. A. Kuada J. A. Araujo 《Journal of Radioanalytical and Nuclear Chemistry》1992,166(1):75-83
In the actinide separation process using TBP as extractant, hydrolytic and radiolytic reactions cause a gradual decomposition of the extractant, resulting in the formation of degradation products which can affect process performance adversely. The TBP diluent has to be cleaned from these degradation products before it is reused. This paper deals with a procedure for solvent cleanup, using a fourstage continuous contactor for increasing the scrubbing efficiency. 相似文献
10.
Angel L. Esteban Maria P. Galache Francisco Mora Ernesto Diez Jesus San Fabian 《Journal of computational chemistry》1989,10(7):887-895
An equation is formulated on the basis of theoretical INDO/FPT calculations which describes the angular dependence of the propanic long-range coupling constant 4JMeH in substituted HCCCH3 fragments. This equation is a truncated Fourier series in the torsion angle ?, HCCMe, which takes into account the dependence of the Fourier coefficients on the bond angle θ, CCMe. The substituent effects are assumed to be additive. Some parameters in the equation may be obtained from the 4JMeH couplings in propane and neopentane derivatives. The calculated effect upon 4JMeH of changes in the bond angle θ is significant and it seems to be in part the cause of some effects which have been attributed to conformational dependence. 相似文献