全文获取类型
收费全文 | 31008篇 |
免费 | 4629篇 |
国内免费 | 8195篇 |
专业分类
化学 | 22585篇 |
晶体学 | 667篇 |
力学 | 2164篇 |
综合类 | 888篇 |
数学 | 4237篇 |
物理学 | 13291篇 |
出版年
2024年 | 27篇 |
2023年 | 240篇 |
2022年 | 668篇 |
2021年 | 743篇 |
2020年 | 751篇 |
2019年 | 840篇 |
2018年 | 783篇 |
2017年 | 984篇 |
2016年 | 1007篇 |
2015年 | 1247篇 |
2014年 | 1410篇 |
2013年 | 1942篇 |
2012年 | 2059篇 |
2011年 | 3275篇 |
2010年 | 2423篇 |
2009年 | 2469篇 |
2008年 | 2176篇 |
2007年 | 1984篇 |
2006年 | 2027篇 |
2005年 | 1913篇 |
2004年 | 2484篇 |
2003年 | 1703篇 |
2002年 | 1727篇 |
2001年 | 1575篇 |
2000年 | 1137篇 |
1999年 | 853篇 |
1998年 | 643篇 |
1997年 | 455篇 |
1996年 | 373篇 |
1995年 | 345篇 |
1994年 | 314篇 |
1993年 | 627篇 |
1992年 | 633篇 |
1991年 | 412篇 |
1990年 | 436篇 |
1989年 | 422篇 |
1988年 | 175篇 |
1987年 | 98篇 |
1986年 | 96篇 |
1985年 | 68篇 |
1984年 | 53篇 |
1983年 | 50篇 |
1982年 | 31篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 23篇 |
1966年 | 6篇 |
1965年 | 19篇 |
1964年 | 8篇 |
1936年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
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
![点击此处可从《Biomedical chromatography : BMC》网站下载免费的PDF全文](/ch/ext_images/free.gif)
2.
Zhen Xi 《中国科学:化学(英文版)》2015,(3):434-435
Redox-based post-translational modification of protein thiols has become an attractive strategy in cellular homeostasis and cell signaling.Due to the reductive end of the redox buffer network,the vicinal dithiol-containing proteins(VDPs)maintains an appropriate oxidation-reduction state of proteins through the reversible transformation from vicinal dithiols to disulfide,which is responsible for a variety of 相似文献
3.
Lijuan Shen Li Li Sheng Lu Xiaohan Zhang Jie Liu Junlin An Guojun Zhang Bo Wu Fei Wang 《中国颗粒学报》2015,(3):10-15
We conducted measurements of black carbon(BC) aerosol in Jiaxing,China during autumn from September 26 to November 30,2013.We investigated temporal and diurnal variations of BC,and its correlations with meteorological parameters and other major pollutants.Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3,with an average of 5.1 μg/m3.The diurnai variation of BC exhibited a bimodal distribution,with peaks at 07:00 and 18:00.The morning peak was larger than the evening peak.The mass percentages of BC in PM2.5 and PM10 were 7.1%and 4.8%,respectively.The absorption coefficient of BC was calculated to be 44.4 Mm-1,which accounted for 11.1%of the total aerosol extinction.BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11 μg/m3 during the measurement period.Correlation analysis indicated that the main sources of BC were motor vehicle exhaust,and domestic and industrial combustion. 相似文献
4.
5.
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
6.
Hui Li Jian Liu Juan Zhao Huiting He Dr. Dabo Jiang Prof. Steven Robert Kirk Prof. Qiong Xu Dr. Xianxiang Liu Prof. Dulin Yin 《ChemistryOpen》2021,10(4):477-485
A series of tetraimidazolium salts with different anions was prepared and applied in the isomerization of β-pinene oxide. After examining the activity of different catalysts, a remarkable enhancement of the selectivity of perillyl alcohol (47 %) was obtained over [PEimi][HNO3]4 under mild reaction conditions and using DMSO as the solvent. Furthermore, noncovalent interactions between solvent molecules and the catalyst were found by FT-IR spectroscopy and confirmed by computational chemistry. The homogeneous catalyst showed excellent stability and was reused up to six times without significant loss. 相似文献
7.
8.
9.
Journal of Thermal Analysis and Calorimetry - The fire behavior of one flame-retardant PVC cable used as building wire is investigated in this work. Bench scale tests were performed using a cone... 相似文献
10.
Ionics - This study aims to explore the potential merits of palladium oxide sensing electrode. PdO is applied on a solid-state potentiometric sensor on an yttria-stabilized zirconia (YSZ)... 相似文献