全文获取类型
收费全文 | 9098篇 |
免费 | 243篇 |
国内免费 | 29篇 |
专业分类
化学 | 5573篇 |
晶体学 | 85篇 |
力学 | 227篇 |
数学 | 1253篇 |
物理学 | 2232篇 |
出版年
2021年 | 94篇 |
2020年 | 120篇 |
2019年 | 107篇 |
2018年 | 88篇 |
2017年 | 83篇 |
2016年 | 202篇 |
2015年 | 165篇 |
2014年 | 196篇 |
2013年 | 378篇 |
2012年 | 406篇 |
2011年 | 443篇 |
2010年 | 271篇 |
2009年 | 262篇 |
2008年 | 374篇 |
2007年 | 399篇 |
2006年 | 361篇 |
2005年 | 323篇 |
2004年 | 269篇 |
2003年 | 257篇 |
2002年 | 240篇 |
2001年 | 178篇 |
2000年 | 174篇 |
1999年 | 127篇 |
1998年 | 124篇 |
1997年 | 134篇 |
1996年 | 142篇 |
1995年 | 128篇 |
1994年 | 101篇 |
1993年 | 124篇 |
1992年 | 115篇 |
1991年 | 93篇 |
1989年 | 96篇 |
1988年 | 94篇 |
1987年 | 85篇 |
1986年 | 84篇 |
1985年 | 132篇 |
1984年 | 112篇 |
1983年 | 89篇 |
1982年 | 107篇 |
1981年 | 115篇 |
1980年 | 72篇 |
1979年 | 89篇 |
1978年 | 94篇 |
1977年 | 95篇 |
1976年 | 86篇 |
1975年 | 88篇 |
1973年 | 77篇 |
1968年 | 91篇 |
1967年 | 102篇 |
1966年 | 100篇 |
排序方式: 共有9370条查询结果,搜索用时 15 毫秒
71.
Robbert Dijkgraaf Erik Verlinde Herman Verlinde 《Communications in Mathematical Physics》1988,115(4):649-690
We study the theory ofc=1 torus and 2-orbifold models on general Riemann surfaces. The operator content and occurrence of multi-critical points in this class of theories is discussed. The partition functions and correlation functions of vertex operators and twist fields are calculated using the theory of double covered Riemann surfaces. It is shown that orbifold partition functions are sensitive to the Torelli group. We give an algebraic construction of the operator formulation of these nonchiral theories on higher genus surfaces. Modular transformations are naturally incorporated as canonical transformations in the Hilbert space. 相似文献
72.
Nanoscale organization of the pathogen receptor DC-SIGN mapped by single-molecule high-resolution fluorescence microscopy. 总被引:3,自引:0,他引:3
Bärbel I. de Bakker Dr. Frank de Lange Dr. Alessandra Cambi Dr. Jeroen P. Korterik Erik M. H. P. van Dijk Dr. Niek F. van Hulst Prof. Carl G. Figdor Prof. Maria F. Garcia‐Parajo Prof. 《Chemphyschem》2007,8(10):1473-1480
DC-SIGN, a C-type lectin exclusively expressed on dendritic cells (DCs), plays an important role in pathogen recognition by binding with high affinity to a large variety of microorganisms. Recent experimental evidence points to a direct relation between the function of DC-SIGN as a viral receptor and its spatial arrangement on the plasma membrane. We have investigated the nanoscale organization of fluorescently labeled DC-SIGN on intact isolated DCs by means of near-field scanning optical microscopy (NSOM) combined with single-molecule detection. Fluorescence spots of different intensity and size have been directly visualized by optical means with a spatial resolution of less than 100 nm. Intensity- and size-distribution histograms of the DC-SIGN fluorescent spots confirm that approximately 80 % of the receptors are organized in nanosized domains randomly distributed on the cell membrane. Intensity-size correlation analysis revealed remarkable heterogeneity in the molecular packing density of the domains. Furthermore, we have mapped the intermolecular organization within a dense cluster by means of sequential NSOM imaging combined with discrete single-molecule photobleaching. In this way we have determined the spatial coordinates of 13 different individual dyes, with a localization accuracy of 6 nm. Our experimental observations are all consistent with an arrangement of DC-SIGN designed to maximize its chances of binding to a wide range of microorganisms. Our data also illustrate the potential of NSOM as an ultrasensitive, high-resolution technique to probe nanometer-scale organization of molecules on the cell membrane. 相似文献
73.
74.
A. Schmidt 《Fresenius' Journal of Analytical Chemistry》1966,219(3):280
Ohne Zusammenfassung 相似文献
75.
76.
A. Schmidt 《Fresenius' Journal of Analytical Chemistry》1968,238(4):309
Ohne Zusammenfassung 相似文献
77.
Gerhard Full Peter Winterhalter Gertraut Schmidt Peter Herion Peter Schreier 《Journal of separation science》1993,16(11):642-644
This paper reports the differentiation between the enantiomers of theaspiranes and theaspirones, potent flavor compounds widely used in the flavor industry. Optically pure reference compounds of isomeric theaspiranes were obtained by enantioselective synthesis. Enantiomerically pure reference theaspirones were isolated from quince fruit; their absolute stereochemistry was assigned by CD spectroscopy. For both types of compounds the order of elution was elucidated by using authentic reference compounds. These data enabled the determination of the enantiomeric distribution of both types of compounds in a variety of plant tissues. Because of the complexity of the natural flavor isolates, compounds were identified by mass spectrometry after multidimensional gas chromatography employing a Sichromat 2 double oven chromatograph. After separation of the target compounds on the first, achiral, column (DB-5), they were transferred to a chiral column (C-Dex B) for determination of the enantiomeric distribution. Multiple ion detection (MID) enabled the determination of the enantiomeric distribution even for complex mixtures containing the target compounds at extremely low levels. 相似文献
78.
79.
Doshi DA Shah PB Singh S Branson ED Malanoski AP Watkins EB Majewski J van Swol F Brinker CJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):7805-7811
Neutron reflectivity (NR) is used to probe the solid, liquid, vapor interface of a porous superhydrophobic (SH) surface submerged in water. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160 degrees (superhydrophobic) to <10 degrees (hydrophilic). NR shows that the superhydrophobic nature of the surface prevents infiltration of water into the porous film. Atomic force microscopy and density functional theory simulations are used in combination to interpret the NR results and help establish the location, width, and nature of the SH film-water interface. 相似文献
80.
A. Schmidt 《Fresenius' Journal of Analytical Chemistry》1966,223(1):42-43
Ohne Zusammenfassung 相似文献