全文获取类型
收费全文 | 19933篇 |
免费 | 693篇 |
国内免费 | 9篇 |
专业分类
化学 | 11249篇 |
晶体学 | 80篇 |
力学 | 372篇 |
数学 | 2709篇 |
物理学 | 6225篇 |
出版年
2021年 | 152篇 |
2020年 | 222篇 |
2019年 | 156篇 |
2018年 | 190篇 |
2017年 | 192篇 |
2016年 | 472篇 |
2015年 | 420篇 |
2014年 | 427篇 |
2013年 | 847篇 |
2012年 | 826篇 |
2011年 | 1053篇 |
2010年 | 470篇 |
2009年 | 396篇 |
2008年 | 893篇 |
2007年 | 873篇 |
2006年 | 822篇 |
2005年 | 721篇 |
2004年 | 560篇 |
2003年 | 538篇 |
2002年 | 502篇 |
2001年 | 446篇 |
2000年 | 355篇 |
1999年 | 315篇 |
1998年 | 253篇 |
1997年 | 258篇 |
1996年 | 302篇 |
1995年 | 281篇 |
1994年 | 257篇 |
1993年 | 286篇 |
1992年 | 297篇 |
1991年 | 230篇 |
1990年 | 202篇 |
1989年 | 190篇 |
1988年 | 174篇 |
1987年 | 204篇 |
1986年 | 211篇 |
1985年 | 251篇 |
1984年 | 259篇 |
1983年 | 224篇 |
1982年 | 237篇 |
1981年 | 266篇 |
1980年 | 220篇 |
1979年 | 212篇 |
1978年 | 243篇 |
1977年 | 209篇 |
1976年 | 199篇 |
1975年 | 200篇 |
1974年 | 162篇 |
1973年 | 168篇 |
1967年 | 160篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
21.
Phenomena accompanying electrochemical doping of solid fullerene films with potassium were studied by sputter ion depth profiling
(XPS and SIMS). The potassium distribution was determined, and artifacts associated with possible damage of the layer composition
caused by ion impact were investigated and discussed. To compare the charge transfer while reductive doping is taking place
at fullerene/solution interface with doping from gas phase, model layers were prepared and doped by potassium under UHV conditions.
It was found that sputtering by Ar+ primary ions yields both accurate information on the alkaline metal distribution and on its concentration. Sputtering by
O+ ions led to an enrichment of potassium, apparently due to the reactivity of oxygen with the fullerene matrix. It is shown
that the reductive doping starts at the fullerene/solution interface. The concentration of potassium in the doped films was
found to be lower than expected from the charge transferred during the electrochemical reduction. Other phase transformations
such as hydrogenation are discussed.
Received March 4, 2002; accepted July 26, 2002 相似文献
22.
23.
We examine certain special features exhibited by various classes of linear operators acting in a hereditarily indecomposable
Banach space. For instance, we show that the family of all Riesz operators in a H.I. space forms a closed, 2-sided ideal.
We also give further characterizations of the class of scalar-type spectral operators (to those already given in [16]). The
final section discusses some properties of the spectral maximal spaces of (necessarily decomposable) linear operators in such
spaces.
Conferenza tenuta il 16 settembre 1997
The support of the German Academic Exchange Scheme (DAAD) is gratefully acknowledged 相似文献
24.
Ralf Jäger Anatolij I. Saprykin J. Sabine Becker Hans -Joachim Dietze José A. C. Broekaert 《Mikrochimica acta》1997,125(1-4):41-44
The analytical capabilities of a high-resolution mass spectrometer in combination with a 13.56 MHz glow discharge ion source for the analysis of semiconducting materials (silicon carbide and gallium arsenide) were studied. It was shown that single positively charged ions of sample material have about 10 eV higher average energy than the ions of the discharge and residual gas. Therefore effective energy separation of the ions of analyte from the ions of the discharge and residual gas was achieved by adjusting the ion transfer optics (breadth and position of energy slit), which improves the analytical capabilities of the developed method.Some analytical applications are presented to illustrate the performance of r.f. GDMS for the bulk analysis of semiconducting materials. The results of the trace element analysis of gallium arsenide and silicon carbide samples are compared with data of independent methods (LIMS, ICP-AES, SIMS).Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthdayOn leave from the Institute of Inorganic Chemistry, 630090 Novosibirsk, Russia 相似文献
25.
26.
L. Landström D. Brodoceanu K. Piglmayer D. Bäuerle 《Applied Physics A: Materials Science & Processing》2006,84(4):373-377
Extraordinary optical transmission through metal-coated close-packed monolayers has been observed. The monolayers consist of silica (a-SiO2) or polystyrene microspheres that form two-dimensional close-packed lattices by self-assembly. Metal layers of Ag, Au and Ni with different thicknesses (larger than the skin depth) were evaporated onto such lattices by means of standard techniques. The optical transmission spectra investigated between 300 and 2500 nm show pronounced peaks that scale with the diameter and the optical properties of the composite slabs. The enhanced transmission observed is most likely mediated via plasmons. PACS 78.66.-w; 81.16.Dn; 82.70.Dd 相似文献
27.
S. Trebert Haeberlin F. Lux J. Karl T. Spruss H. Schönenberger 《Journal of Radioanalytical and Nuclear Chemistry》1987,113(2):461-467
As part of an examination of the cytostatic effects of 1,2-diarylethylenediamine-platinum(II)-complexes the contents of platinum and biologically essential trace elements of tumour tissue and different organs were determined. The activation analysis procedure — separation of32P, isolation of199Au and99Mo — is described. In the course of a pharmakokinetical experiment with tumourbearing rats (DMBA induced hormone-dependent tumours) the desired enrichment of the administered drug in the tumour tissue was found. Changes of the trace element level of tumour tissue were found for hormone-dependent MXT-mammary tumours on mice. 相似文献
28.
29.
Vlasov Yu. G. Murzina Yu. G. Legin A. V. Ermolenko Yu. E. Schubert J. Schüoning M. J. Lut H. 《Russian Journal of Applied Chemistry》2002,75(3):351-356
Methods of silicon planar technology and pulsed laser deposition were applied to fabricate fully solid-state chemical sensors for determining ions of copper, lead, cadmium, thallium, and also sulfide and chloride ions on the basis of thin chalcogenide films as ion-sensitive membranes. 相似文献
30.
Differentiation of functions w.r.t. finite atomless measures with compact support on the real line is introduced. The related harmonic calculus is similar to that of the classical Lebesgue case. As an application we obtain the Weyl exponent for the spectral asymptotics of the Laplacians w.r.t. linear Cantor-type measures with arbitrary weights. 相似文献