全文获取类型
收费全文 | 8946篇 |
免费 | 256篇 |
国内免费 | 26篇 |
专业分类
化学 | 5602篇 |
晶体学 | 97篇 |
力学 | 251篇 |
数学 | 1091篇 |
物理学 | 2187篇 |
出版年
2021年 | 110篇 |
2020年 | 130篇 |
2019年 | 119篇 |
2018年 | 96篇 |
2016年 | 202篇 |
2015年 | 176篇 |
2014年 | 175篇 |
2013年 | 361篇 |
2012年 | 398篇 |
2011年 | 406篇 |
2010年 | 227篇 |
2009年 | 227篇 |
2008年 | 369篇 |
2007年 | 355篇 |
2006年 | 364篇 |
2005年 | 337篇 |
2004年 | 231篇 |
2003年 | 241篇 |
2002年 | 208篇 |
2001年 | 186篇 |
2000年 | 165篇 |
1999年 | 118篇 |
1998年 | 125篇 |
1997年 | 122篇 |
1996年 | 137篇 |
1995年 | 123篇 |
1994年 | 102篇 |
1993年 | 123篇 |
1992年 | 109篇 |
1991年 | 101篇 |
1990年 | 74篇 |
1989年 | 97篇 |
1988年 | 98篇 |
1987年 | 95篇 |
1986年 | 96篇 |
1985年 | 135篇 |
1984年 | 123篇 |
1983年 | 96篇 |
1982年 | 115篇 |
1981年 | 126篇 |
1980年 | 85篇 |
1979年 | 89篇 |
1978年 | 98篇 |
1977年 | 106篇 |
1976年 | 94篇 |
1975年 | 95篇 |
1973年 | 82篇 |
1968年 | 93篇 |
1967年 | 102篇 |
1966年 | 103篇 |
排序方式: 共有9228条查询结果,搜索用时 15 毫秒
21.
F. Schmidt und Hänsch 《Fresenius' Journal of Analytical Chemistry》1884,23(1):530-531
Ohne Zusammenfassung 相似文献
22.
Erhard Schmidt 《Mathematische Zeitschrift》1940,46(1):204-230
Ohne ZusammenfassungHerrn Oskar Perron zum 60. Geburtstag am 7. Mai 1940 gewidmet 相似文献
23.
M. De Falco F. De Giovanni C. Musella R. Schmidt 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):70-76
A subgroupH of a groupG is said to bepermutable ifHX=XH for every subgroupX ofG. In this paper the structure of groups in which every subgroup either is abelian or permutable is investigated.
This work was done while the last author was visiting the University of Napoli Federico II. He thanks the “Dipartimento di
Matematica e Applicazioni” for its financial support. 相似文献
24.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
25.
Synthesis and Properties of the Layered Perovskite Phase Sr3Mo1.5Zn0.5O7‐δ The new layered perovskite phase Sr3Mo1.5Zn0.5O7‐δ was synthesized by solid state reaction using a Zn/ZnO oxygen buffer. The crystal structure was refined from X‐ray powder pattern by the Rietveld method. The compound crystallizes tetragonal in the space group I4/mmm (no. 139) with the lattice parameters a = 3.9631(3) Å, c = 20.583(1) Å. An oxygen deficiency corresponding to δ ≈ 0.25 was determinated, indicating the presence of molybdenum in mixed valence (Mo4+ and Mo6+). 相似文献
26.
Frank W. Schmidt 《Linear and Multilinear Algebra》1991,30(3):229-230
This section appears from time to time. Contributions are invited, and should be submitted to R. C. Thompson, Mathematics Department, University of California, Santa Barbara, CA 93106. 相似文献
27.
28.
29.
30.
H. Falk R. Geerling B. Hattendorf K. Krengel-Rothensee K. P. Schmidt 《Analytical and bioanalytical chemistry》1997,359(4-5):352-356
An ICP-MS method for the determination of ultra-traces of 24 Elements (Li, Be, Mg, Al, Cr, Mn, Co, Zn, Cu, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Ba, Tl, Pb, Bi, U) at ng/L to μg/L levels in highly saline solutions (up to 30 g/L NaCl) was developed. Calculated to the salt content of the samples, limits of detection at the sub-μg/kg level were obtained. This allows the measurement of samples like sea water, or clinical samples like urine, serum and whole blood, with few or without sample preparation and a drastic improvement to the limits of detection. Compared to the determination in solutions of 1 g/L NaCl the limits of detection in the original sample were improved by one order of magnitude. Improvements in instrumental stability are achieved by the use of an additional gas, that is introduced to the aerosol stream and avoids salt deposition in the aerosol tube of the torch, the use of High Matrix Content (HMC) cones, that show no clogging even at NaCl-concentrations up to 50 g/L. With this setup the long term stability for measurements with changing matrix concentrations is < 10% without and < 5% with use of an internal standard for the individual samples. Cleaning up is necessary after 2 days of operation. The direct analysis of the Nearshore Seawater Reference Material NRC-CNRC CASS3 showed a good agreement with the certified and measured concentrations. Elements, that do not suffer from an isobaric overlap of matrix compounds can be determined clearly at ng/L levels. Measurement of different matrix concentrations showed, that acceptable results can be achieved with a single calibration for concentrations from 5 g/L NaCl to 30 g/L NaCl, though matrix matching shows the best results. 相似文献