全文获取类型
收费全文 | 5378篇 |
免费 | 134篇 |
国内免费 | 73篇 |
专业分类
化学 | 3093篇 |
晶体学 | 24篇 |
力学 | 258篇 |
数学 | 1010篇 |
物理学 | 1200篇 |
出版年
2023年 | 33篇 |
2022年 | 115篇 |
2021年 | 130篇 |
2020年 | 118篇 |
2019年 | 135篇 |
2018年 | 140篇 |
2017年 | 108篇 |
2016年 | 180篇 |
2015年 | 142篇 |
2014年 | 172篇 |
2013年 | 303篇 |
2012年 | 327篇 |
2011年 | 345篇 |
2010年 | 222篇 |
2009年 | 194篇 |
2008年 | 309篇 |
2007年 | 261篇 |
2006年 | 294篇 |
2005年 | 271篇 |
2004年 | 210篇 |
2003年 | 170篇 |
2002年 | 158篇 |
2001年 | 90篇 |
2000年 | 76篇 |
1999年 | 70篇 |
1998年 | 47篇 |
1997年 | 41篇 |
1996年 | 46篇 |
1995年 | 41篇 |
1994年 | 54篇 |
1993年 | 33篇 |
1992年 | 40篇 |
1991年 | 40篇 |
1990年 | 34篇 |
1989年 | 34篇 |
1988年 | 28篇 |
1987年 | 31篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1983年 | 24篇 |
1982年 | 27篇 |
1980年 | 25篇 |
1979年 | 33篇 |
1977年 | 24篇 |
1976年 | 42篇 |
1975年 | 27篇 |
1974年 | 24篇 |
1973年 | 23篇 |
1972年 | 24篇 |
1967年 | 25篇 |
排序方式: 共有5585条查询结果,搜索用时 62 毫秒
61.
Ahlen S Ambrosio M Antolini R Auriemma G Baker R Baldini A Bam BB Barbarino GC Barish BC Battistoni G Bellotti R Bemporad C Bernandini P Bilokon H Bisi V Bloise C Bower C Bussino S Cafagna F Calicchio M Campana D Campana P Carboni M Cecchini S Cei F Chiarella V Cormack R Corona A Coutu S De Cataldo G Dekhissi H De Marzo C De Vincenzi M Di Credico A Diehl E Erriquez O Favuzzi C Ficenec D Forti C Fusco P Giacomelli G Giannini G Giglietto N Giubellino P Grassi M Green P Grillo A Guarino F 《Physical review letters》1994,72(5):608-612
62.
Spectrographic data from observations of the polarized weak steplike (with relatively sharp growth t 3 sec and slow decay t 102 sec) solar continuum radioemission are analyzed below. The main results are found using a sweeping spectrograph in the 8–12 GHz frequency range (sweep rate 1 sample per second and frequency resolution 120 MHz) and using the RT-22 radio telescope at the Crimean Astrophysical Observatory (angular resolution 4–6). In a series of events at the leading edge of the continuum a narrow-band frequency drifting emission termed blip-type is found. The degree of continuum circular polarization (p<10%) is low compared to that of the narrow-band component (p20%). Both components of the aforementioned events should be radiating on the second harmonic of the local plasma frequency in the context of a plasma generating mechanism. Based on the model proposed and using the observed degree of circular polarization of each component, we can estimate the strength of the magnetic field within the area of the source and the width of the angular spectrum from the radiating plasma turbulence. The results of analysis of the real microwave events are given below.Radiophysical Research Institute, Nizhnii Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 7, pp. 874–882, July, 1994. 相似文献
63.
64.
65.
66.
67.
Acylation of phosphine oxide anions with derivatives of cyclic anhydrides or oxidative cleavage of cyclic allyl phosphine oxides gives Ph2PO-ketoacids: reduction, separation of diastereoisomers, and completion of the Horner-Wittig reaction gives single isomers () or () of unsaturated acids. 相似文献
68.
S. P. Dolin A. A. Levin T. Yu. Mikhailova N. S. Strokach M. V. Solin E. V. Polyakov 《Journal of Molecular Structure》2004,700(1-3):199-205
An effect of molecular vibrational modes within the dimers [O3AO–(H/D)OAO3]3− on behavior of H-bond protons or deuterons is studied theoretically for H-bonded antiferroelectrics and quantum paraelectrics of the M3(H/D)(AO4)2 family (M=alkali metal, A=S, Se). The ‘heavy’ reorganization modes in D-species of this family and both reorganization and promoting modes in corresponding H-analogues are examined. It is shown that the analysis with due regard for the reorganization modes results in insignificant decreasing of the effective tunneling frequency of light nuclei. Hence the reasonable estimations of the critical temperature of the low-temperature phase transition in M3D(AO4)2 materials are available only with additional corrections related to potential profiles of a deuteron. It is noted that in the limits of the proposed model the promoting mode in the case of H-species can favor, in principle, the increasing as well as the decreasing of effective proton level splitting. 相似文献
69.
70.