全文获取类型
收费全文 | 203827篇 |
免费 | 1757篇 |
国内免费 | 571篇 |
专业分类
化学 | 105790篇 |
晶体学 | 2834篇 |
力学 | 10364篇 |
综合类 | 11篇 |
数学 | 22053篇 |
物理学 | 65103篇 |
出版年
2021年 | 2088篇 |
2020年 | 2169篇 |
2019年 | 2737篇 |
2018年 | 3815篇 |
2017年 | 3776篇 |
2016年 | 4976篇 |
2015年 | 2503篇 |
2014年 | 4477篇 |
2013年 | 8806篇 |
2012年 | 7088篇 |
2011年 | 8282篇 |
2010年 | 6616篇 |
2009年 | 6761篇 |
2008年 | 7758篇 |
2007年 | 7698篇 |
2006年 | 6749篇 |
2005年 | 5948篇 |
2004年 | 5653篇 |
2003年 | 5170篇 |
2002年 | 5167篇 |
2001年 | 5609篇 |
2000年 | 4145篇 |
1999年 | 3133篇 |
1998年 | 2704篇 |
1997年 | 2717篇 |
1996年 | 2414篇 |
1995年 | 2152篇 |
1994年 | 2269篇 |
1993年 | 2187篇 |
1992年 | 2473篇 |
1991年 | 2601篇 |
1990年 | 2510篇 |
1989年 | 2566篇 |
1988年 | 2497篇 |
1987年 | 2501篇 |
1986年 | 2364篇 |
1985年 | 2994篇 |
1984年 | 3063篇 |
1983年 | 2568篇 |
1982年 | 2527篇 |
1981年 | 2499篇 |
1980年 | 2299篇 |
1979年 | 2684篇 |
1978年 | 2646篇 |
1977年 | 2853篇 |
1976年 | 2854篇 |
1975年 | 2646篇 |
1974年 | 2584篇 |
1973年 | 2691篇 |
1972年 | 2073篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
41.
International Applied Mechanics - The theorems (statements) on the existence of attractor are proved. A generalized Shilnikov theorem is formulated. In the expression for the saddle of a homoclinic... 相似文献
42.
Complex Study of the Spearhead Superficial Crust from Burial Mound no. 1 near Novosvobodnaya Village
Loboda A. Yu. Kolobylina N. N. Veligzhanin A. A. Zubavitchus Y. V. Tereshchenko E. Yu. Shishlina N. I. Yatsishina E. B. Kashkarov P. K. 《Crystallography Reports》2018,63(2):295-301
A complex study of a spearhead dated back to IV mill. BC from burial mound no. 1 near Novosvobodnaya village (collection of the State Historical Museum) and, in particular, the material of spearhead superficial crust has been performed. The elemental and phase composition of the metal of spearhead and the superficial crust on its surface have been determined by scanning electron microscopy, jointly with energydispersive X-ray microanalysis and X-ray phase analysis. A comparative analysis of the results of studying the spearhead superficial crust and similar crusts on other artifacts from the mounds near Novosvobodnaya village suggest natural origin of the crust on copper?arsenic artifacts.
相似文献43.
Yanxia Xu Yanbing Lv Ruili Wu Huaibin Shen Huawei Yang Han Zhang Jinjie Li Lin Song Li 《Particle & Particle Systems Characterization》2020,37(3):1900441
Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium-based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1-octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD-based fluorescence-linked immunosorbent assay (QD-FLISA) for quantitative detection of C-reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL−1, correlation coefficient: R2 = 0.9992). The limit of detection is 2.9 ng mL−1, which increases twofold compared to previously reported cadmium-free QD-based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium-free sensitive and specific immunoassays in biomedical fields. 相似文献
44.
45.
46.
47.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
48.
49.
50.