全文获取类型
收费全文 | 1962篇 |
免费 | 4篇 |
国内免费 | 4篇 |
专业分类
化学 | 631篇 |
晶体学 | 8篇 |
力学 | 234篇 |
数学 | 268篇 |
物理学 | 829篇 |
出版年
2021年 | 32篇 |
2020年 | 26篇 |
2019年 | 25篇 |
2018年 | 46篇 |
2017年 | 38篇 |
2016年 | 44篇 |
2015年 | 20篇 |
2014年 | 48篇 |
2013年 | 62篇 |
2012年 | 60篇 |
2011年 | 62篇 |
2010年 | 74篇 |
2009年 | 89篇 |
2008年 | 90篇 |
2007年 | 98篇 |
2006年 | 79篇 |
2005年 | 64篇 |
2004年 | 68篇 |
2003年 | 69篇 |
2002年 | 68篇 |
2001年 | 50篇 |
2000年 | 41篇 |
1999年 | 29篇 |
1998年 | 32篇 |
1997年 | 22篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 22篇 |
1993年 | 24篇 |
1992年 | 24篇 |
1991年 | 18篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 35篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 22篇 |
1982年 | 30篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 34篇 |
1978年 | 19篇 |
1977年 | 25篇 |
1975年 | 25篇 |
1974年 | 18篇 |
1973年 | 23篇 |
1972年 | 20篇 |
1971年 | 15篇 |
排序方式: 共有1970条查询结果,搜索用时 250 毫秒
61.
By the catalytic condensation of azomethines with aliphatic-aromatic and heterocyclic ketones, derivatives of 5,6-benzoquinoline containing thiophene or pyridine rings as substituents have been synthesized. 相似文献
62.
Dikusar E. A. Potkin V. I. Vashkevich E. V. Kozlov N. G. Kaberdin R. V. 《Russian Journal of General Chemistry》2004,74(4):578-581
(Z)-2-Naphthylacetylene was synthesized by the reaction of (Z)-3-(2-naphthyl)-3-chloropropenal (prepared from 2-acetylnaphthalene) with aqueous NaOH in dioxane. The reactions of 2-naphthylacetylene with CuCl, [Ag(NH3)2]NO3, and K2[HgI4] gave copper, silver, and mercury 2-naphthylacetylenides, respectively. Silver naphthylacetylenide reacts with iodine to give the iodoethynyl derivative, which readily takes up bromine across the triple bond. 相似文献
63.
A study was made of the charged state on a natural or an oxidized germanium surface during heat-and-field treatment. This study dealt with the kinetics of charging and discharging of superslow surface states. The thermal activation energy of these charging and discharging processes has also been evaluated. Conclusions are drawn about the possible nature of superslow traps in the Ge-GeO2 system.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.2, pp.79–86, February, 1976.In conclusion, the authors thank V. F. Kiselev for the useful discussion of this report and his valuable comments. 相似文献
64.
65.
66.
S. S. Koval’skaya N. G. Kozlov V. Kulcitki A. Aricu N. Ungur 《Russian Journal of Organic Chemistry》2013,49(2):303-311
Sclareol under the mild conditions of Ritter reaction is converted into N,N′-[(8R,13)-labdan-14(15)-ene-8,13-diyl]diacetamides stereoisomeric at the C13 atom possessing the unrearranged skeleton of the initial diol. One of the minor reaction products is the N-[(8α,13)-epoxylabdan-14-yl]acetamide whose formation requires the intermediate cyclization of the sclareol. Under more severe conditions and at the reversed order of the reagents addition the prevailing components of the reaction mixture are cyclized and rearranged N-[(8α,14)-epoxy-16(13→14)-abeo-labdan-13-yl]acetamides stereoisomeric at the C13 atom, and minor compounds, (8α,13)-epoxy-16(13→14)-abeo-labdan-12(13)-ene and (8α,14)-epoxy-16(13→4)-abeo-labdan-12(13)-ene. 相似文献
67.
68.
Yu. D. Zavartsev M. V. Zavertyaev A. I. Zagumenniy A. F. Zerrouk V. A. Kozlov S. A. Kutovoi N. V. Pestovskii A. A. Petrov S. Yu. Savinov 《Bulletin of the Lebedev Physics Institute》2016,43(11):336-339
Optical and luminescence characteristics of Lu2+2ySi1-yO5+y (LFS) scintillation crystals are studied before and after irradiation with doses to 45 Mrad from a 60Co source. LFS crystals were doped with Ce3+, Sc3+, Ca2+, and Y3+ ions with various concentrations. The dependence of the radiation resistance of LFS crystals on Ce ion concentration is detected. For the crystal of composition Ce:Sc:Ca:Y:LFS, it was found that its optical transmission (OT) and pulsed cathodoluminescence (PCL) spectra before irradiation do not differ from the spectra measured after irradiation with a dose of 45 Mrad within experimental error. The nature of the radiation resistance of rare-earth lutetium oxyorthosilicates (LFS) is discussed. 相似文献
69.
E. V. Konovalova O. B. Perevalova N. A. Koneva K. V. Ivanov E. V. Kozlov 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(8):807-810
The rearrangement of the grain structure of Ni3Fe alloy upon an A1 → L12 phase transition is studied via transmission electron microscopy in combination with the electron backscatter diffraction. It is established that the formation of fresh grain boundaries of general and special types occurs, with the proportion of special-type grain boundaries in the grain boundary ensemble growing. The spectrum of the special grain boundaries changes, due to an increase of the proportion of grain boundaries Σ3 and Σ9. This strengthens the texture of the long-range ordered alloy. 相似文献
70.