全文获取类型
收费全文 | 1016篇 |
免费 | 54篇 |
国内免费 | 3篇 |
专业分类
化学 | 713篇 |
晶体学 | 6篇 |
力学 | 5篇 |
数学 | 144篇 |
物理学 | 205篇 |
出版年
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 15篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 8篇 |
2017年 | 16篇 |
2016年 | 34篇 |
2015年 | 47篇 |
2014年 | 35篇 |
2013年 | 58篇 |
2012年 | 76篇 |
2011年 | 63篇 |
2010年 | 43篇 |
2009年 | 33篇 |
2008年 | 55篇 |
2007年 | 74篇 |
2006年 | 36篇 |
2005年 | 42篇 |
2004年 | 36篇 |
2003年 | 40篇 |
2002年 | 45篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1973年 | 7篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1967年 | 5篇 |
1889年 | 3篇 |
排序方式: 共有1073条查询结果,搜索用时 78 毫秒
81.
Dirk Steinhilber Torsten Rossow Dr. Stefanie Wedepohl Florian Paulus Dr. Sebastian Seiffert Prof. Dr. Rainer Haag 《Angewandte Chemie (International ed. in English)》2013,52(51):13538-13543
pH‐Cleavable cell‐laden microgels with excellent long‐term viabilities were fabricated by combining bioorthogonal strain‐promoted azide–alkyne cycloaddition (SPAAC) and droplet‐based microfluidics. Poly(ethylene glycol)dicyclooctyne and dendritic poly(glycerol azide) served as bioinert hydrogel precursors. Azide conjugation was performed using different substituted acid‐labile benzacetal linkers that allowed precise control of the microgel degradation kinetics in the interesting pH range between 4.5 and 7.4. By this means, a pH‐controlled release of the encapsulated cells was achieved upon demand with no effect on cell viability and spreading. As a result, the microgel particles can be used for temporary cell encapsulation, allowing the cells to be studied and manipulated during the encapsulation and then be isolated and harvested by decomposition of the microgel scaffolds. 相似文献
82.
Summary The corrosion of Ag(100), Ag(110) and Ag(111) single crystal surfaces by chlorine has been investigated at sample temperatures T = 90 K. After exposures to typically 30 to 50 l Cl2 in all three cases one and the same disordered corrosion product AgCl is observed covered by condensed molecular Cl2. Obviously, the underlying corrosion mechanism is not face-specific and may be generalized to arbitrary Ag surfaces, including polycrystalline films. It is demonstrated that ultraviolet photoemission spectroscopy is a unique tool for identifying the reaction products of halogenation processes and for elucidating elementary steps of the underlying corrosion mechanism.
UV-Photoemissionsstudien zur chlorinduzierten Korrosion von Silberoberflächen相似文献
83.
T. Wenzel J. Bosbach A. Goldmann F. Stietz F. Träger 《Applied physics. B, Lasers and optics》1999,69(5-6):513-517
An experimental method to tailor the shape and the optical absorption spectra of metallic nanoparticles is presented. It exploits
the influence of laser irradiation on particle growth by self-assembly of atoms deposited on a substrate surface. By applying
nanosecond light pulses of appropriate fluence and three different wavelengths, oblate silver particles with three fixed axial
ratios have been fabricated. Their optical extinction spectra were measured with s- and p-polarized light and are dominated
by plasmon resonances at fixed photon energies determined by the axial ratio. Possible applications of such tailormade nanoclusters
include catalytic converters and optical components with narrow-band extinction, the magnitude and center frequency of which
can be specified in advance.
Received: 9 September 1999 / Published online: 20 October 1999 相似文献
84.
Tobias Krüger Katja Vorndran Dr. Torsten Linker Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):12082-12091
Arenes with various alkyl side‐chains were synthesized in high yields and excellent regioselectivities. Starting from toluic and naphthoic acids, the carboxylate group was conveniently substituted by alkyl halides by Birch reduction and subsequent decarbonylation. The method is characterized by inexpensive starting materials and reagents, and methylation of arenes was realized. Besides simple alkyl substituents, the scope of arene functionalization was extended by benzyl, fluoro, amino, and ester groups. We were able to control the alkylation of 1‐naphthoic acid during Birch reduction by the addition of tert‐butanol. This allowed the regioselective synthesis of mono and bis‐substituted naphthalenes from the same starting material. 相似文献
85.
86.
Summary. We consider singularly perturbed linear elliptic problems in two dimensions. The solutions of such problems typically exhibit
layers and are difficult to solve numerically. The streamline diffusion finite element method (SDFEM) has been proved to produce
accurate solutions away from any layers on uniform meshes, but fails to compute the boundary layers precisely. Our modified
SDFEM is implemented with piecewise linear functions on a Shishkin mesh that resolves boundary layers, and we prove that it
yields an accurate approximation of the solution both inside and outside these layers. The analysis is complicated by the
severe nonuniformity of the mesh. We give local error estimates that hold true uniformly in the perturbation parameter , provided only that , where mesh points are used. Numerical experiments support these theoretical results.
Received February 19, 1999 / Revised version received January 27, 2000 / Published online August 2, 2000 相似文献
87.
In this paper, the long-run dynamics of a resonant converter is studied. The modelling of the resonant converter can be done using various approximations and the long-run dynamics of the two dimensional cases were earlier analysed. In this paper, we discuss results that can be extended to the three dimensional case. It seems that limit cycles describe the long-run dynamics in important situations in the three dimensional case, too. Our objective is to relate the limit cycles found previously in the two-dimensional case to those found now in the three dimensional approximation. 相似文献
88.
89.
Torsten Teorell 《Colloid and polymer science》1930,53(3):322-338
Ohne Zusammenfassung 相似文献
90.