全文获取类型
收费全文 | 3279篇 |
免费 | 139篇 |
国内免费 | 7篇 |
专业分类
化学 | 2218篇 |
晶体学 | 49篇 |
力学 | 123篇 |
数学 | 340篇 |
物理学 | 695篇 |
出版年
2023年 | 24篇 |
2022年 | 63篇 |
2021年 | 71篇 |
2020年 | 72篇 |
2019年 | 60篇 |
2018年 | 58篇 |
2017年 | 56篇 |
2016年 | 119篇 |
2015年 | 93篇 |
2014年 | 134篇 |
2013年 | 202篇 |
2012年 | 287篇 |
2011年 | 270篇 |
2010年 | 178篇 |
2009年 | 149篇 |
2008年 | 218篇 |
2007年 | 212篇 |
2006年 | 192篇 |
2005年 | 142篇 |
2004年 | 135篇 |
2003年 | 105篇 |
2002年 | 110篇 |
2001年 | 57篇 |
2000年 | 56篇 |
1999年 | 24篇 |
1998年 | 19篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1974年 | 6篇 |
1973年 | 6篇 |
排序方式: 共有3425条查询结果,搜索用时 15 毫秒
11.
The dry etching characteristics of transparent and conductive indium-zinc oxide (IZO) films have been investigated using an inductively coupled high-density plasma. While the Cl2-based plasma mixture showed little enhancement over physical sputtering in a pure argon atmosphere, the CH4/H2/Ar chemistry produced an increase of the IZO etch rate. On the other hand, the surface morphology of IZO films after etching in Ar and Ar/Cl2 discharges is smooth, whereas that after etching in CH4/H2/Ar presents particle-like features resulting from the preferential desorption of In- and O-containing products. Etching in CH4/H2/Ar also produces formation of a Zn-rich surface layer, whose thickness (∼40 nm) is well-above the expected range of incident ions in the material (∼1 nm). Such alteration of the IZO layer after etching in CH4/H2/Ar plasmas is expected to have a significant impact on the transparent electrode properties in optoelectronic device fabrication. 相似文献
12.
Microstructure effect on chemical etching behavior of the annealed Ti-6Al-4V and Ti-3Al-2.5V titanium (Ti) alloys was compared with that of unalloyed commercially pure titanium. The microstructural evolution of structure phases after annealing the titanium and its alloys at temperature near and above β transus and followed by furnace cooling to room temperature was studied using optical microscope, scanning electron microscope and X-ray diffraction techniques. The microstructure study illustrates that the heat treatment enhanced partitioning effect allows extensive formation of hemispherical and near spherical pits roughened surface to be readily acquired by chemically etching the annealed α + β titanium alloys. The kinetics of the chemical etching reaction process show a linear dependence on time. The annealed α + β titanium alloys that exhibit relatively lower weight loss and thickness reduction rate illustrate less chemical activity than the annealed unalloyed titanium. 相似文献
13.
So-Yon Lim Matt Meyer Richard A Kjonaas Swapan K Ghosh 《Journal of immune based therapies and vaccines》2007,5(1):3-1
This is a correction article. 相似文献
14.
Young-Bae Seu Taeg-Kyeong Lim Chang-Jin Kim Sun-Chul Kang 《Tetrahedron: Asymmetry》1995,6(12):3009-3014
Optically active epoxy alcohol, (R)-2-butyryloxymethylglycidol3 which is the precursor of a tert-alcohol chiral building block was obtained in high enantiomeric purity, 98.7% e.e., by lipase-catalyzed asymmetric hydrolysis using a phosphate buffer and organic co-solvent system in 95% of chemical yield. 相似文献
15.
16.
We examine the problem of building or fortifying a network to defend against enemy attacks in various scenarios. In particular,
we examine the case in which an enemy can destroy any portion of any arc that a designer constructs on the network, subject
to some interdiction budget. This problem takes the form of a three-level, two-player game, in which the designer acts first
to construct a network and transmit an initial set of flows through the network. The enemy acts next to destroy a set of constructed
arcs in the designer’s network, and the designer acts last to transmit a final set of flows in the network. Most studies of
this nature assume that the enemy will act optimally; however, in real-world scenarios one cannot necessarily assume rationality
on the part of the enemy. Hence, we prescribe optimal network design algorithms for three different profiles of enemy action:
an enemy destroying arcs based on capacities, based on initial flows, or acting optimally to minimize our maximum profits
obtained from transmitting flows. 相似文献
17.
18.
19.
Teik-Cheng Lim 《Czechoslovak Journal of Physics》2004,54(5):553-559
A theoretical relation between the Bauer-Maysenholder-Seeger (BMS) and the Biswas-Hamann (BH) potential function has been developed herein for the case of 2-body interaction. By equating derivatives of these two potential functions for the 2-body part, a loose form of BMS is expressed in terms of BH parameters with a scaling factor. The validity of the developed parametric relationships has been graphically demonstrated, and the suitability discussed with reference to the extent and direction of bond distortion. 相似文献
20.
A new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid. 相似文献