全文获取类型
收费全文 | 13574篇 |
免费 | 307篇 |
国内免费 | 53篇 |
专业分类
化学 | 9468篇 |
晶体学 | 65篇 |
力学 | 238篇 |
数学 | 2435篇 |
物理学 | 1728篇 |
出版年
2020年 | 133篇 |
2016年 | 233篇 |
2015年 | 217篇 |
2014年 | 194篇 |
2013年 | 465篇 |
2012年 | 421篇 |
2011年 | 512篇 |
2010年 | 315篇 |
2009年 | 324篇 |
2008年 | 479篇 |
2007年 | 510篇 |
2006年 | 452篇 |
2005年 | 504篇 |
2004年 | 450篇 |
2003年 | 368篇 |
2002年 | 351篇 |
2001年 | 180篇 |
2000年 | 196篇 |
1999年 | 183篇 |
1998年 | 165篇 |
1997年 | 207篇 |
1996年 | 207篇 |
1995年 | 207篇 |
1994年 | 195篇 |
1993年 | 198篇 |
1992年 | 201篇 |
1991年 | 172篇 |
1990年 | 149篇 |
1989年 | 181篇 |
1988年 | 210篇 |
1987年 | 176篇 |
1986年 | 197篇 |
1985年 | 253篇 |
1984年 | 222篇 |
1983年 | 190篇 |
1982年 | 236篇 |
1981年 | 220篇 |
1980年 | 217篇 |
1979年 | 214篇 |
1978年 | 192篇 |
1977年 | 189篇 |
1976年 | 178篇 |
1975年 | 168篇 |
1974年 | 178篇 |
1973年 | 171篇 |
1971年 | 130篇 |
1961年 | 159篇 |
1960年 | 213篇 |
1959年 | 125篇 |
1958年 | 136篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
101.
Ronny Kleinhempel Gunar Kaune Matthias Herrmann Hartmut Kupfer Walter Hoyer Frank Richter 《Mikrochimica acta》2006,156(1-2):61-67
Indium tin oxide (ITO) thin films were deposited by mid frequency pulsed dual magnetron sputtering using a metallic alloy
target with 10 wt.% tin in an atmosphere of argon and oxygen. The aim of the work was to study the interdependence of structural,
electrical and optical properties of ITO films deposited in the reactive and transition target mode, respectively. The deposition
rate in the transition mode exceeds the deposition rate in the reactive mode by a factor of six, a maximum value of 100 nm·m min−1 could be achieved. This corresponds to a static deposition rate of 200 nm min−1. The lowest electrical resistivity of 1.1·10−3 Ω cm was measured at samples deposited in the high oxygen flow range in the transition mode. The samples show a good transparency
in the visible range corresponding to extinction coefficients being below 10−2. X-ray diffraction was used to characterise crystalline structure as well as film stress. ITO films prepared in the transition
mode show a slightly preferred orientation in (211) direction, whereas films deposited in the reactive mode are strongly (222)
oriented. Compared to undoped In2O3 all samples have an enlarged lattice. The lattice strain perpendicular to the surface is about 0.8% and 2.0% for films grown
in the transition and the reactive mode, respectively. Deposition in the transition mode introduces a biaxial film stress
in the range of −300 MPa, while stress in reactive mode samples is −1500 MPa. 相似文献
102.
103.
Klaus Weisskopf 《Journal of polymer science. Part A, Polymer chemistry》1988,26(7):1919-1935
The use of the solvent mixture chloroform/hexafluoroisopropanol (98 : 2 vol %) in the GPC-analysis of polyethylene terephthalate (PET) is described. PET-samples of different molecular weight have been prepared and characterized by light scattering, viscometry, and improved techniques of osmometry and end group titration. These well characterized samples were used in calibrating the GPC. The calibration with polydisperse standards was found superior to the universal calibration procedure in the solvent system chosen. 相似文献
104.
Klaus G. Heumann 《Trends in analytical chemistry : TRAC》1982,1(15):357-361
Isotope dilution mass spectrometry is an important method for accurate and precise determination of trace- and micro-amounts of the elements. Using different ionization techniques in the mass spectrometer most of the elements of the periodic table can be analysed. 相似文献
105.
Nelson Durán Klaus Zinner Roberto Casadei de Baptista Carmen C. C. Vidigal Giuseppe Cilento 《Photochemistry and photobiology》1976,24(4):383-388
Abstract— The thiophenyl ester of indole-3-acetic acid and indole-3-acetonitrile produce chemiluminescence in aerated dimethylsulfoxide in the presence of potassium t -butoxide. The emitter is the aromatic aldehyde. In the case of acetonitrile, the other product expected from the cleavage of an intermediate dioxetane, cyanate/isocyanate, has also been identified. Other auxins also chemiluminesce under similar conditions, but the emitters have not been properly identified.
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
These systems are models for the peroxidase catalyzed oxidation of indole-3-acetic acid to indole-3-carboxaldehyde and as such support the earlier inference (Vidigal et al , 1975) that the excited aldehyde is generated in the enzymic process.
An additional result is the observation of an exciplex between excited indole-3-carboxaldehyde and the thiophenylester of indole-3-acetic acid. This appears to be the first case of chemical generation of an exciplex by a route other than radical ion reaction, presumably by the dioxetane route. 相似文献
106.
107.
Schell Daniel J. Walter Pamela J. Johnson David K. 《Applied biochemistry and biotechnology》1992,34(1):659-665
Applied Biochemistry and Biotechnology - The enzymatic digestibility of a pretreated substrate is enhanced by increasing the severity of the pretreatment conditions, apparently because a greater... 相似文献
108.
109.
Ohne Zusammenfassung 相似文献
110.