全文获取类型
收费全文 | 936篇 |
免费 | 23篇 |
国内免费 | 2篇 |
专业分类
化学 | 653篇 |
晶体学 | 9篇 |
力学 | 17篇 |
数学 | 141篇 |
物理学 | 141篇 |
出版年
2023年 | 7篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 42篇 |
2012年 | 39篇 |
2011年 | 60篇 |
2010年 | 33篇 |
2009年 | 33篇 |
2008年 | 41篇 |
2007年 | 58篇 |
2006年 | 57篇 |
2005年 | 38篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 30篇 |
2000年 | 30篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 16篇 |
1992年 | 8篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 12篇 |
1971年 | 8篇 |
1937年 | 7篇 |
排序方式: 共有961条查询结果,搜索用时 15 毫秒
1.
2.
3.
Single nanocrystal arrays on patterned poly(ethylene glycol) copolymer microstructures using selective wetting and drying 总被引:1,自引:0,他引:1
Suh KY Khademhosseini A Eng G Langer R 《Langmuir : the ACS journal of surfaces and colloids》2004,20(15):6080-6084
Single nanocrystal arrays were fabricated on sub-microwells of poly(ethylene glycol) (PEG) copolymer using selective wetting on the hydrophilic regions of the exposed substrate surface and subsequent drying. Templates were produced by molding a thin film of a PEG-based random copolymer on hydrophilic substrates such as glass or silicon dioxide. The polymeric microstructures provide a topographical barrier around the well, which makes it possible to create nanocrystal arrays with controlled geometrical features. The size of the nanocrystal was found to decrease with decreasing well size and also decrease with decreasing topological height. A simple empirical equation was derived to predict the size of the crystal as a function of the pattern size and height, which is in good agreement with the experimental data. 相似文献
4.
Es werden die Reaktionen des konjugierten Systems
von 2-Methyl-o-chinolacetat I mit Verbindungen, die aktive Methylengruppen enthalten, beschrieben, wobei unter 1,4-Addition und Essigsäureabspaltung die Bildung von substuierten o-Kresolen (B) eintritt.
Die ersten vorläufigen Versuche hat Herr Dr.W. Metlesics durchgeführt (Dissertation Wien, 1955). 相似文献
Die ersten vorläufigen Versuche hat Herr Dr.W. Metlesics durchgeführt (Dissertation Wien, 1955). 相似文献
5.
M Bárány D G Spigos E Mok P N Venkatasubramanian A C Wilbur B G Langer 《Magnetic resonance imaging》1987,5(5):393-398
Water-suppressed and slice-selective proton spectra of live human brain exhibited several resonances that were tentatively assigned to metabolites such as N-acetylaspartate, glutamate, phosphocreatine and creatine, choline derivatives, and taurine. In the liver spectrum of a healthy volunteer, the major resonance was tentatively assigned to a fatty acyl methylene and the minor resonances to protons in carnitine, taurine, glutamate, and glutamine. In the spectrum of a cancerous liver, resonances in addition to those present in the normal liver were seen. Protein degradation in the liver with cancer was indicated by resonances from urea and from the ring protons in tryptophan, tyrosine, and phenylalanine. Furthermore, increased nucleic acid synthesis was indicated by resonances from nucleotide protons. 相似文献
6.
One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the
heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation,
metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition
technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy
(SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction
built-in-potential (V
D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark
and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied. 相似文献
7.
This is a survey of the papers by M. G. Krein (and his disciples) devoted to the theory of operators in spaces with an indefinite metric and its applications.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 46, Nos. 1–2, pp. 5–17, January–February, 1994. 相似文献
8.
Braverman Michael SH.; Stepanov Vladimir D. 《Bulletin London Mathematical Society》1994,26(3):283-287
Necessary and sufficient conditions for the boundedness of thediscrete Hardy operator of the form , from to when 0 < q < 1 <p , is given. 相似文献
9.
10.
E. Ben-Jacob H. Brand G. Dee L. Kramer J.S. Langer 《Physica D: Nonlinear Phenomena》1985,14(3):348-364
We discuss the problem of pattern selection in situations where a stable, nonuniform state of a nonlinear dissipative system propagates into an initially unstable, homogeneous region. Our strategy is to consider this process as a generalization of front propagation in a nonlinear diffusion problem for which rigorous results are known; and we point out that these known properties are consistent with a marginal-stability hypothesis that has been suggested in the theory of dendritic crystal growth. We then describe a more general interpretation of the marginal-stability hypothesis and, finally, present numerical evidence for its validity from three different pattern-forming models. 相似文献