全文获取类型
收费全文 | 480篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
化学 | 298篇 |
力学 | 8篇 |
数学 | 93篇 |
物理学 | 94篇 |
出版年
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 32篇 |
2012年 | 24篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 10篇 |
2008年 | 27篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 17篇 |
2004年 | 20篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1992年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1970年 | 9篇 |
1966年 | 3篇 |
1959年 | 3篇 |
1943年 | 2篇 |
1934年 | 2篇 |
1933年 | 3篇 |
1930年 | 2篇 |
排序方式: 共有493条查询结果,搜索用时 8 毫秒
401.
A. Gunther M. Khoury S. Mili
i D. Vasileska T. Thornton S. M. Goodnick 《Superlattices and Microstructures》2000,27(5-6)
We report on the transport properties of novel Si quantum dot structures with controllable electron number through both top and side gates. Quantum dots were fabricated by a split-gate technique within a standard MOSFET process. Four-terminal dc electrical measurements were performed at 4.2 K in a liquid helium cryostat. Strong oscillations in the conductance through the dot are observed as a function of both the top gate bias and of the plunger bias. An overall monotonic and quasi-periodic movement of the peak conductance is observed which is believed to be associated with the bare level structure of the electronic states in the dot coupled with the Coulomb charging energy. Crossing behavior is observed as well, suggestive of either many-body effects or symmetry breaking of the dot states by the applied bias. 相似文献
402.
Ohne Zusammenfassung 相似文献
403.
404.
405.
406.
Extra-ordinary mechanical features and high corrosion resistance are essential qualities of CrNi-steels and nickel base alloys.
The corrosion resistance of these materials fundamentally depends on their surface conditions. Tarnish colours and welding
scale, formed during thermal treatment or joining, are removed by pickling components made of these alloys with sulphuric
acid, nitric acid and hydrofluoric acid as well. By this kind of surface refinement several million tons per annum of aggressive
waste waters are produced, that cause high environmental risks and not acceptable employee endangerings. Therefore, a project
was promoted by the DECHEMA e.V. to replace hydrofluoric acid by organic complexing agents. The related surface analytical
examinations are reported in this publication. 相似文献
407.
A Mumford curve of genus g=5,6,7 or 8 over a non-Archimedean field ofcharacteristic p (such that if p=0, the residue field characteristic exceeds 5) has at most 12(g–1) automorphisms. In this paper, all curves that attain this bound and their automorphism groups (called of Lamé type) are explicitly determined. 相似文献
408.
We classify graph C
*-algebras, namely, Cuntz-Krieger algebras associated to the Bass-Hashimoto edge incidence operator of a finite graph, up to
strict isomorphism. This is done by a purely graph theoretical calculation of the K-theory of the C
*-algebras and the method also provides an independent proof of the classification up to Morita equivalence and stable equivalence
of such algebras, without using the boundary operator algebra. A direct relation is given between the K
1-group of the algebra and the cycle space of the graph.
We thank Jakub Byszewski for his input in Sect. 2.8. The position of the unit in K
0(
Ч) was guessed based on some example calculations by Jannis Visser in his SCI 291 Science Laboratory at Utrecht University
College. 相似文献
409.
Rianasari I Walder L Burchardt M Zawisza I Wittstock G 《Langmuir : the ACS journal of surfaces and colloids》2008,24(16):9110-9117
Laterally structured, self-assembled monolayers (SAMs) of different thiols (HS-R-X, R = (CH 2) 3-16, X = -CH 3, -COOH, -NH 2) on gold have been prepared by inkjet printing. The printer is a modified, low-cost desktop printer (Epson Stylus Photo R200), the ink is a 1 mM solution of the thiol in ethanol/glycerol (6:1). The quality of inkjet-printed large area SAMs obtained in this study is between that of a layer self-assembled from a thiol solution and that obtained by soft lithography, according to cyclic voltammetry, electrochemical impedance spectroscopy, scanning electrochemical microscopy (SECM), and polarization-modulated Fourier transform infrared reflection-absorption spectroscopy (PM IRRAS). For the first time, simultaneous printing of two different thiols in a single print job as an alternative to sequential printing and backfilling is demonstrated. The smallest structures consisting of conductive disks of 40 microm diameter were analyzed as single spots by SECM and as random array electrodes with different average disk-disk distance. Conductive band electrodes with variable bandwidth (300 microm to 1 cm) are presented, as well as a pH switchable band structure. As compared to stamping, inkjet printing allows for simultaneous multiple thiol printing in a single print job with the resolution limited only by the droplet size and the precision of the translation stage. 相似文献
410.
Mahler C Müller U Müller WM Enkelmann V Moon C Brunklaus G Zimmermann H Höger S 《Chemical communications (Cambridge, England)》2008,(39):4816-4818
A transition metal free route to phenyl substituted oligophenylenes that tolerates halogens is described. 相似文献