全文获取类型
收费全文 | 1655篇 |
免费 | 32篇 |
国内免费 | 3篇 |
专业分类
化学 | 787篇 |
晶体学 | 10篇 |
力学 | 34篇 |
数学 | 157篇 |
物理学 | 702篇 |
出版年
2021年 | 10篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 26篇 |
2015年 | 21篇 |
2014年 | 26篇 |
2013年 | 68篇 |
2012年 | 67篇 |
2011年 | 63篇 |
2010年 | 47篇 |
2009年 | 36篇 |
2008年 | 65篇 |
2007年 | 71篇 |
2006年 | 69篇 |
2005年 | 66篇 |
2004年 | 51篇 |
2003年 | 24篇 |
2002年 | 53篇 |
2001年 | 36篇 |
2000年 | 30篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 47篇 |
1995年 | 49篇 |
1994年 | 42篇 |
1993年 | 57篇 |
1992年 | 43篇 |
1991年 | 23篇 |
1990年 | 38篇 |
1989年 | 16篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 18篇 |
1985年 | 22篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1982年 | 20篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 25篇 |
1978年 | 21篇 |
1977年 | 19篇 |
1976年 | 16篇 |
1975年 | 20篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1972年 | 10篇 |
排序方式: 共有1690条查询结果,搜索用时 15 毫秒
211.
Various addition-elimination approaches have been explored for diastereoselective construction of 1-amino- 1-cyclopropane-carboxylic acid (ACPC) derivatives, and the desired product was obtained from a reaction of cyclo(NAc-L-Val-NAc-Gly) and methyl α-bro-moacrylate under protonic solvent. 相似文献
212.
M. Campbell K.W.D. Ledingham A.D. Baillie M.L. Fitzpatrick J.Y. Gourlay J.G. Lynch 《Nuclear Physics A》1975,249(2):349-365
Recent review papers have indicated that experimental K.-capture to positon emission ratios in allowed decays disagree with theory especially for high-Z nuclei. The experimental error has never been sufficiently small to verify this with certainty. The K-capture to positon emission ratio, , in 120Sb has been measured with an uncertainty of about 3% and found to lie about 16% lower than the most recent theoretical predictions. 相似文献
213.
T.J. McKenna S.J. Campbell D.H. Chaplin G.V.H. Wilson 《Journal of magnetism and magnetic materials》1980,20(2):207-211
The technique of transient enhancement of the ac initial susceptibility χ has been used to compare domain effects in the ferromagnetic-paramagnetic transition of Gd and the ferromagnetic-antiferromagnetic transition of Dy. The temperature hysteresis in both χ and enhanced χ in the AF region of Dy indicates the existence of domains. The results for Dy support the suggestion that the transition from ferromagnetic to antiferromagnetic order upon warming in the vicinity of the Curie temperature takes place via an intermediate, moment-bearing domain structure. 相似文献
214.
215.
216.
217.
Room temperature Mössbauer spectra of Cr1?xFex alloys (x=0.05–0.26) have been fitted using a pseudo-lorentzian lineshape; this leads to the widths of gaussian processes which contribute to the line broadening. The variation of isomer shift with composition can be described well by an extension to the cellular model of Miedema and co-workers. Estimations of the contributions of the s electron charge transfer and the s-d electron conversions to the isomer shift are presented. 相似文献
218.
G. Lhersonneau B. Pfeiffer J. R. Persson J. Suhonen J. Toivanen P. Campbell P. Dendooven A. Honkanen M. Huhta P. M. Jones R. Julin S. Juutinen M. Oinonen H. Penttilä K. Peräjärvi A. Savelius W. Jicheng J. C. Wang J. Äystö 《Zeitschrift für Physik A Hadrons and Nuclei》1997,358(3):317-327
The decay of 99Nb to 99Mo has been investigated. The use of the ion-guide technique for on-line mass separation and of a Ge-array for γ-ray detection have allowed the observation of decay branchings lower than 10?3. Mediumspin levels, some already known from reaction studies and new ones at high energy, are populated. The β-feeding patterns of the decays of the 9/2+ states in 99Nb and in its isotones 97Y, and 101Tc are qualitatively reproduced by QRPA calculations. 相似文献
219.
220.
M. A. Lovell J. D. Robertson W. D. Ehmann W. R. Markesbery W. J. Teesdale J. L. Campbell 《Journal of Radioanalytical and Nuclear Chemistry》1995,195(1):7-12
Results of micro-PIXE analysis of senile plaques (SP) in Alzheimer's disease (AD) brain have been utilized to independently confirm levels of iron (Fe) as measured by LMMS in adjacent brain sections. LMMS concentrations were calculated based on the preparation and analysis of an iron calibration curve prepared in our laboratory. The LMMS standards consist of ironcis-dicyclohexano-18-crown-6 ether coordination complexes dissolved in Spurr's low viscosity embedding medium. To our knowledge, this is the first report of the use of micro-PIXE, with its spatial resolution and detection limits comparable to that of LMMS, in the validation of LMMS results. The agreement observed between results obtained for Fe by micro-PIXE and LMMS indicates that the use of our LMMS standards, at least in the case of Fe, yields accurate results. 相似文献