全文获取类型
收费全文 | 2003篇 |
免费 | 137篇 |
国内免费 | 9篇 |
专业分类
化学 | 1438篇 |
晶体学 | 25篇 |
力学 | 63篇 |
数学 | 248篇 |
物理学 | 375篇 |
出版年
2023年 | 15篇 |
2022年 | 90篇 |
2021年 | 60篇 |
2020年 | 49篇 |
2019年 | 82篇 |
2018年 | 61篇 |
2017年 | 45篇 |
2016年 | 105篇 |
2015年 | 73篇 |
2014年 | 78篇 |
2013年 | 142篇 |
2012年 | 119篇 |
2011年 | 110篇 |
2010年 | 86篇 |
2009年 | 87篇 |
2008年 | 104篇 |
2007年 | 117篇 |
2006年 | 95篇 |
2005年 | 69篇 |
2004年 | 66篇 |
2003年 | 55篇 |
2002年 | 51篇 |
2001年 | 47篇 |
2000年 | 35篇 |
1999年 | 28篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 19篇 |
1983年 | 8篇 |
1981年 | 11篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1973年 | 6篇 |
1971年 | 6篇 |
1901年 | 4篇 |
1862年 | 8篇 |
排序方式: 共有2149条查询结果,搜索用时 0 毫秒
151.
Hani Kbashi Sergey V. Sergeyev Chengbo Mou Amos Martinez Garcia Mohammed Al Araimi Aleksei Rozhin Stanislav Kolpakov Vladimir Kalashnikov 《Annalen der Physik》2018,530(5)
During the last two decades, revealing mechanisms of origin waves with anomalous amplitude (rogue waves) have been in the focus of researchers from different fields ranging from oceanography to laser physics. Mode‐locked lasers, as a test bed system, provide a unique opportunity to collect more data on rogue waves in the form of random pulses (soliton rain) and to clarify the mechanisms of rogue‐wave emergence caused by soliton–soliton and soliton–dispersive wave interactions. Here, for the first time, for an Er‐doped mode‐locked laser, a new type of vector rogue waves is demonstrated experimentally and theoretically, which is driven by desynchronization of the orthogonal linear states of polarization, so leading to output power oscillations in the form of anomalous spikes‐dips (bright‐dark rogue waves). The results can pave the way to unlocking the universal nature of the origin of rogue waves and thus can be of interest to the broad scientific community. 相似文献
152.
S. V. Titov A. P. Gorbenko R. A. Yakshibaev L. A. Reznichenko R. F. Al’mukhametov V. V. Titov L. A. Shilkina 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(5):719-720
The ion conductivity, crystal structure, and multifractal parameters of the sections of grain boundaries in CuCr1?x V x S2 superionic conductors with 0 ≤ x ≤ 0.3 have been investigated. It is established that an increase in the surface area of grain boundaries and complication of their shape in such compounds facilitate ion transport. The effect of crystal structure peculiarities on the grain structure of these compounds has been revealed. 相似文献
153.
154.
155.
Saleh A. Ahmed Ziad Moussa Shaya Y. Al‐Raqa Saleh N. Alamry 《Journal of Physical Organic Chemistry》2009,22(6):593-606
Multi‐addressable photophysical properties of new synthesized photochromic materials based on photochromic dihydroindolizine system (DHI) covalently linked to N‐acyl‐11 aminoundecanoic acid (AUDA) or to its sodium salt or to its ester, through an amidic or urethane linkage have been studied. The DHI skeleton in these compounds is substituted in both the fluorene part (region A) or in the heterocyclic base (region B) with the gelling moieties. These molecules have been designed to respond to their environment. Interestingly, they are shown to act as efficient gelators for polar organic fluids, water and obviously they exhibit a thermosensitive answer as low molecular mass organogelators. In these fluids, the aggregative properties are totally suppressed upon conversion to neutral carboxylic species. The gels of these carboxylate sodium salts are shown to be markedly affected by light irradiation. Supramolecular gelating assemblies can be disrupted by the photoinduced ring opening of the DHI subunit, so that the macroscopic flowing property is recovered. Upon a further thermal treatment, the system is reversibly converted back to the supramolecular network. Controlled gelation could be achieved using temperature, light, or acidity as external stimuli. These new synthesized photochromic gels with their multi‐addressable properties will find their applications as super photoresponsive materials. Developing and tuning of the photophysical properties of the synthesized compounds by the amide and urethane substituents in the 4‐position of the fluorene and pyridazine regions have been achieved. The absorption maxima (λmax) and the half‐lives (t1/2) of the colored betaines were detected in all cases using UV/VIS spectrophotometric measurements. Irradiation of DHI 12‐20 in CH2Cl2 or in acetonitrile solutions at ambient temperature with polychromatic light leads to the formation of red to red‐violet colored betaines 12 ′ ‐20 ′. The kinetics of the bleaching process of betaines 12 ′ ‐20 ′ to DHIs 12‐20 were found to take place in the second range (96‐218 s) and fit well the first order thermal back reaction. Some of these DHIs showed a photostability higher than that of the standard one. These interesting photophysical properties will help this family of compounds to find useful applications. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
156.
Sahar Al Akoum-Ebrik Mohamed Ansar Rahima Mouhoub Claude Vaccher Marie-Pierre Vaccher Nathalie Flouquet 《光谱学快报》2013,46(5):925-944
The enantiomeric composition and absolute configuration of 4-Amino-3-(benzo[b]furan-2-yl)-Butanoic Acids and of 4-Amino-3-(thien-2-yl)-Butanoic Acids 1 may be accurately determined by 1H and 13C nuclear magnetic resonance analysis of the corresponding derivatives 3 prepared by reaction with chiral reagents. Correlation with HPLC is signaled. 相似文献
157.
We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate. 相似文献
158.
159.
Al. Al. Berlin und V. G. Omjan 《Colloid and polymer science》1980,258(8):994
Ohne Zusammenfassung 相似文献
160.
V. I. Al’shits V. N. Lyubimov A. Radowicz 《Journal of Experimental and Theoretical Physics》2005,101(1):107-119
The conditions of existence of the zero components of electric field E and electric induction D accompanying a volume acoustic wave propagating in a piezoelectric medium have been studied. General equations describing the positions of the zero-field lines E(m) = 0 and the zero-induction points m0, such that D(m0) = 0 on the unit sphere (m2 = 1) of the wave propagation directions, are obtained. General theorems determining the conditions ensuring the existence of such lines and points, even in triclinic crystals, are formulated. The relationship between such directions and various elements of the crystal symmetry is analyzed. The vector fields D(m), which are always orthogonal to the wave normals m, in the vicinity of the zero-induction points m0 exhibit certain orientational singularities characterized by the Poincaré indices n = 0, ±1, ±2. The general analytical expressions are obtained for the n values in crystals with arbitrary anisotropy and specified for a number of crystals belonging to various symmetry classes. The conditions of stability of the orientational singularities with respect to small perturbations of the material moduli and a change in the crystal symmetry are considered. 相似文献