全文获取类型
收费全文 | 2685篇 |
免费 | 101篇 |
国内免费 | 1篇 |
专业分类
化学 | 1545篇 |
晶体学 | 30篇 |
力学 | 119篇 |
数学 | 578篇 |
物理学 | 515篇 |
出版年
2023年 | 24篇 |
2022年 | 27篇 |
2021年 | 26篇 |
2020年 | 64篇 |
2019年 | 76篇 |
2018年 | 83篇 |
2017年 | 69篇 |
2016年 | 131篇 |
2015年 | 91篇 |
2014年 | 120篇 |
2013年 | 359篇 |
2012年 | 130篇 |
2011年 | 135篇 |
2010年 | 99篇 |
2009年 | 95篇 |
2008年 | 125篇 |
2007年 | 95篇 |
2006年 | 102篇 |
2005年 | 57篇 |
2004年 | 73篇 |
2003年 | 55篇 |
2002年 | 51篇 |
2001年 | 55篇 |
2000年 | 35篇 |
1999年 | 40篇 |
1998年 | 35篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 24篇 |
1994年 | 28篇 |
1993年 | 23篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 17篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 30篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 14篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1975年 | 13篇 |
1973年 | 7篇 |
1935年 | 7篇 |
排序方式: 共有2787条查询结果,搜索用时 15 毫秒
1.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
2.
3.
We present some classical solutions to a gauge theory based on quadratically nonlinear Lie algebras without a central term. We observe that instanton-like and meron-like solutions force the internal fields to behave like solitons. 相似文献
4.
P. C. Morais A. C. Oliveira V. K. Garg M. L. Silva E. F. C. Alcântara F. Q. Soares D. Rabelo 《Hyperfine Interactions》2007,177(1-3):51-56
We have used time-differential perturbed angular correlation (PAC) spectroscopy with 181Ta-probes to study the electric field gradient at Zr-sites in synthetic zircon and hafnon between room temperature and 1,200°C. PAC spectra are similar to those obtained from naturally occurring zircons. In particular, a change in slope of the quadrupole coupling vs. temperature is observed in the synthetic zircon at the same temperature as seen in natural zircons from the Mud Tank carbonatite (Australia). The synthetic hafnon data also shows this feature but at somewhat higher temperature. Low-temperature PAC spectra of both synthetic zircon and hafnon have a clearly reduced anisotropy. We believe that the cause for this is a electronic defect, possibly created during the β-decay of the probe parent nucleus. 相似文献
5.
Mustafa Çelebier Ertan Şahin Nilgün Ancın Nurşen Altuntaş Öztaş Selma Gül Öztaş 《应用有机金属化学》2007,21(10):viii-viii
The article referenced above was first published online on 30 August 2007 with incorrect pagination; the pagination has now been corrected online and in print. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
6.
Bahattin Gümgüm Nermin Biricik Feyyaz Durap Ismail Özdemir Nevin Gürbüz Wee Han Ang Paul J. Dyson 《应用有机金属化学》2007,21(8):711-715
Palladium(II) complexes with N,N‐bis(diphenylphosphino)aniline ligands catalyse the Heck reaction between styrene and aryl bromides, affording stilbenes in good yield. The structures of two of the complexes used as pre‐catalysts have been determined by single‐crystal X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
7.
E. I. Ölmez D. Kut A. N. Bilge I. Ölmez 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):227-231
In ambient air, arsenic to selenium ratio (As/Se) is generally found to be less than 1, except in areas influenced by specific
point sources, such as Cu smelters. However, the annual average of this ratio is found to be much higher than unity in Turkey.
This finding is rather unique and may provide a marker for air masses influenced by the coal-related emissions in Turkey.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
Örn Helgason Haraldur P. Gunnlaugsson Siguröur Steinthorsson Steen Mørup 《Hyperfine Interactions》1992,70(1-4):981-984
Mössbauer spectroscopy of basalt lava samples, exhibiting reversible thermal magnetization (JS-T) curves with Curie temperatures of about 580°C, has revealed considerable amounts of maghemite (γ-Fe2O3) in many samples. In view of the expected instability, of maghemite at temperatures above 350°C, this reversibility is rather surprising. Here we report Mössbauer studies on heated lava samples, showing high content of maghemite. The samples were kept at 600°C in oxidizing, reducing, and inactive atmospheres, respectively, for different lengths of time, and then analyzed with Mössbauer spectroscopy at room temperature. The Mössbauer spectra showed that maghemite is stable in the oxidizing atmosphere for at least several hours. In the inactive atmosphere a considerable amount of maghemite still exists after two hours heating. In the reducing atmosphere maghemite had transformed to magnetite after only 30 minutes. 相似文献
9.
We consider a multiperiod mean-variance model where the model parameters change according to a stochastic market. The mean
vector and covariance matrix of the random returns of risky assets all depend on the state of the market during any period
where the market process is assumed to follow a Markov chain. Dynamic programming is used to solve an auxiliary problem which,
in turn, gives the efficient frontier of the mean-variance formulation. An explicit expression is obtained for the efficient
frontier and an illustrative example is given to demonstrate the application of the procedure. 相似文献
10.
In this paper, it is shown that some of the results of torus actions on Poincaré duality spaces, Borel’s dimension formula
and topological splitting principle to local weights, hold if ‘torus’ is replaced by ‘pro-torus’. 相似文献