全文获取类型
收费全文 | 28122篇 |
免费 | 1824篇 |
国内免费 | 1593篇 |
专业分类
化学 | 16005篇 |
晶体学 | 129篇 |
力学 | 442篇 |
综合类 | 611篇 |
数学 | 6482篇 |
物理学 | 7870篇 |
出版年
2023年 | 197篇 |
2022年 | 328篇 |
2021年 | 1151篇 |
2020年 | 601篇 |
2019年 | 716篇 |
2018年 | 478篇 |
2017年 | 502篇 |
2016年 | 665篇 |
2015年 | 758篇 |
2014年 | 948篇 |
2013年 | 1786篇 |
2012年 | 1147篇 |
2011年 | 1322篇 |
2010年 | 1273篇 |
2009年 | 1662篇 |
2008年 | 1759篇 |
2007年 | 1912篇 |
2006年 | 1421篇 |
2005年 | 837篇 |
2004年 | 799篇 |
2003年 | 881篇 |
2002年 | 867篇 |
2001年 | 846篇 |
2000年 | 573篇 |
1999年 | 453篇 |
1998年 | 462篇 |
1997年 | 321篇 |
1996年 | 401篇 |
1995年 | 355篇 |
1994年 | 374篇 |
1993年 | 423篇 |
1992年 | 421篇 |
1991年 | 276篇 |
1990年 | 231篇 |
1989年 | 187篇 |
1988年 | 218篇 |
1987年 | 185篇 |
1986年 | 200篇 |
1985年 | 310篇 |
1984年 | 226篇 |
1983年 | 139篇 |
1982年 | 285篇 |
1981年 | 466篇 |
1980年 | 423篇 |
1979年 | 463篇 |
1978年 | 368篇 |
1977年 | 278篇 |
1976年 | 237篇 |
1974年 | 74篇 |
1973年 | 149篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
993.
994.
We study Brauer–Manin obstructions to the Hasse principle and to weak approximation on algebraic surfaces over number fields. A technique for constructing Azumaya algebra representatives of Brauer group elements is given, and this is applied to the computation of obstructions. 相似文献
995.
996.
Seung-Cheol Lee Kiseong Kim Junghyun Kim Jeong Han Yi Soonchil Lee Chaejoon Cheong 《Magnetic resonance imaging》2009
Magnetic resonance (MR) microscopy of up to 1–5-μm resolutions have been reported previously. The tested phantom structures, however, had widths one order of magnitude bigger than the reported resolutions, e.g., spherical beads or capillary tubes of tens-of-micron diameters or wall thicknesses have been imaged. In this study, we fabricated structures having a few micron widths on a silicon wafer and imaged them using our 1-μm-resolution MR microscopy at 14.1 T. Micron scale width structures were, for the first time, resolved by MR microscopy. 相似文献
997.
Modern advances in radiation medicine – radiodiagnosis, radiotherapy and interventional radiography – each present dosimetry challenges for the medical physicist that did not exist previously. In all of these areas a constant balance has to be made between the treatment necessary to destroy the tumor and the unnecessary exposure of healthy tissue. Innovative applications of OSL dosimetry are now appearing in each of these areas to help the medical physicist and oncologist design the most effective, and least deleterious, treatment for their patients. High sensitivity, precise delivery of light, fast readout times, simpler readers and easier automation are the main advantages of OSL in comparison with TLD.This work aimed to study the application of OSL technique using lithium fluoride dosimeters doped with magnesium and titanium (LiF:Mg,Ti) for application in beta and gamma dosimetry. 相似文献
998.
Binding of multiple proteins to DNA is crucial in many regulatory cellular processes. The kinetics of assembly and disassembly of DNA–multiple protein complexes is very difficult to study in detail due to the lack of suitable experimental approaches. A separation-based approach has been recently proposed to resolve disassembly kinetics of such complexes. While conceptually simple, the separation-based approach generates experimental data with very complex patterns. The analysis of these patterns is a challenging problem on its own. Here we report on a mathematical approach that can extract a solution for the experimental data obtained in separation-based analysis of sequential dissociation of a DNA complex with multiple proteins. This case describes the dissociation of proteins one-by-one from the complex. Generally speaking, a mathematical solution of such problems requires calculations of multiple integrals. Our approach reduces this procedure to taking double integrals and constructing their superposition. We tested this approach with the experimental data obtained for three-step sequential dissociation of complexes of DNA with two protein copies. 相似文献
999.
《Analytical letters》2012,45(12):1305-1313
Abstract The solid monoxime of 2, 3-butanedione is a more convenient material than liquid dione for the homogenous generation of DMG. 2, 3-butanedione dioxime. Determinations of Ni in steels and in pure Ni(II) solutions have shown the optimum pH and order of adding reagents. Gravimetric and/or an EDTA titrimetric finish are possible for a method of reliability within ± 0.2 mg of Ni in 50–150 mg Ni. The solid has the same character and filterability as that from the 1960 dione method of Salesin and Gordon1. 相似文献
1000.
Wine derives its economic value to a large extent from geographical origin, which has a significant impact on the quality of the wine. According to the food legislation, wines can be without geographical origin (table wine) and wines with origin. Wines with origin must have characteristics which are essential due to its region of production and must be produced, processed and prepared, exclusively within that region. 相似文献