全文获取类型
收费全文 | 32914篇 |
免费 | 5643篇 |
国内免费 | 4624篇 |
专业分类
化学 | 23489篇 |
晶体学 | 477篇 |
力学 | 2027篇 |
综合类 | 327篇 |
数学 | 4347篇 |
物理学 | 12514篇 |
出版年
2024年 | 114篇 |
2023年 | 597篇 |
2022年 | 1029篇 |
2021年 | 1094篇 |
2020年 | 1277篇 |
2019年 | 1273篇 |
2018年 | 1143篇 |
2017年 | 1154篇 |
2016年 | 1613篇 |
2015年 | 1645篇 |
2014年 | 1871篇 |
2013年 | 2482篇 |
2012年 | 2869篇 |
2011年 | 2959篇 |
2010年 | 2114篇 |
2009年 | 2048篇 |
2008年 | 2272篇 |
2007年 | 2052篇 |
2006年 | 1899篇 |
2005年 | 1605篇 |
2004年 | 1358篇 |
2003年 | 1160篇 |
2002年 | 1325篇 |
2001年 | 1117篇 |
2000年 | 832篇 |
1999年 | 738篇 |
1998年 | 542篇 |
1997年 | 437篇 |
1996年 | 457篇 |
1995年 | 395篇 |
1994年 | 319篇 |
1993年 | 249篇 |
1992年 | 213篇 |
1991年 | 199篇 |
1990年 | 161篇 |
1989年 | 131篇 |
1988年 | 79篇 |
1987年 | 78篇 |
1986年 | 89篇 |
1985年 | 64篇 |
1984年 | 38篇 |
1983年 | 30篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1975年 | 3篇 |
1969年 | 1篇 |
1957年 | 5篇 |
1936年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Acta Mechanica Sinica - 相似文献
2.
A graphic sequence π =(d1, d2,..., dn) is said to be forcibly k-edge-connected if every realization of π is k-edge-connected. In this paper, we obtain a new sufficient degree condition for π to be forcibly k-edgeconnected. We also show that this new sufficient degree condition implies a strongest monotone degree condition for π to be forcibly 2-edge-connected and a conjecture about a strongest monotone degree condition for π to be forcibly 3-edge-connected due to... 相似文献
3.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
4.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
5.
6.
Analysis and pharmacokinetic study of polyphyllin H in beagle dog plasma after oral administration of Rhizoma Paridis Extracts by LC‐MS/MS 下载免费PDF全文
7.
Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating 下载免费PDF全文
Dr. Swee Kuan Yen D. Prathyusha Varma Wei Mei Guo Dr. Vincent H. B. Ho Dr. Vimalan Vijayaragavan Dr. Parasuraman Padmanabhan Prof. Kishore Bhakoo Prof. Subramanian Tamil Selvan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3914-3918
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging. 相似文献
8.
9.
10.
We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature. 相似文献