全文获取类型
收费全文 | 135篇 |
免费 | 16篇 |
国内免费 | 14篇 |
专业分类
化学 | 78篇 |
晶体学 | 2篇 |
力学 | 20篇 |
综合类 | 2篇 |
数学 | 17篇 |
物理学 | 46篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 3篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 13篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 62 毫秒
21.
利用电化学阳极腐蚀的方法制备了多孔硅膜,实验发现多孔硅膜为多层结构,表面层为纳米结构,其余为微米结构,多孔硅的物理及化学结构的研究表明多孔硅是一种表面上含硅、氧、氢、氟元素组成的化合物包覆着的纳米晶硅粒和微米硅丝.多孔硅的发光主要来自表面纳米结构层,亚微米结构层并未见发光,从实验上证实了多孔硅的发光与量子尺寸效应紧密关联. 相似文献
22.
23.
24.
25.
Qiang Wang Qingqing Chen Guoyu Jiang Mengting Xia Mengjiao Wang Yongdong Li Xiaoming Ma Jianguo Wang Xinggui Gu 《中国化学快报》2019,30(11):1965-1968
An AIEgen decorated porphyrin(TPETPyP) was easily obtained through a one-step reaction.The bulky TPE in TPETPyP greatly impeded the intermolecular π-π stacking of the porphyrin core,which significantly suppressed aggregation-caused quenching(ACQ) effect of TPETPyP in aqueous solution.The four pyridinium salts formed in TPETPyP also render the whole molecule water solubility,which eliminated its aggregation.TPETPyP exhibited ~1 O_2 quantum yield as high as 0.85 in PBS.Moreover,it also showed high binding affinity to proteins,the major biotarget of ~1 O_2.The high ~1 O_2 quantum yield plus the great binding ability of TPETPyP toward proteins makes it a highly-efficient protein photocleaving agent.Protein electrophoresis experiments demonstrated that TPETPyP can photocleave BSA upon visible light irradiation,indicating that TPETPy P can act as a promising photosensitizer(PS) in PDT.The work here will provide a facile strategy to utilize AIEgens modified traditional PSs for photodynamic therapy(PDT). 相似文献
26.
Xuefeng Wu Qing Liu Yongdong Deng Xiaoju Chen Zhi Zheng Shaotong Jiang Xingjiang Li 《Applied biochemistry and biotechnology》2018,184(2):553-569
The use of microorganism fermentation for production of fumaric acid (FA), which is widely used in food, medicine, and other fields, can provide technical support for the FA industry. In this study, we aimed to increase the titer of FA production by using an improved Rhizopus oryzae WHT5, which was domesticated to obtain a furfural-resistant strain in corncob hydrolytes. The metabolic pathways and metabolic network of this strain were investigated, and the related enzymes and metabolic flux were analyzed. Metabolic pathway analysis showed that the R. oryzae WHT5 strain produced FA mainly through two pathways. One occurred in the cytoplasm and the other was a mitochondrial pathway. The key parameters of the fermentation process were analyzed. The FA titer was 49.05 g/L from corncob hydrolytes using R. oryzae WHT5 in a 7-L bioreactor. The use of a furfural-resistant strain developed through domestication effectively increased the titer of FA. This capacity of the microorganisms to produce high amounts of FA by bioconverting corncob hydrolyte can be further applied for industrial production of FA. 相似文献
27.
Huang Xinwei Wang Yongdong Hu Nan Sha Yinhua Ding Dexin 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):739-746
Hydroponic experiments were conducted on the removal of uranium, heavy metals and nutrients from the effluent of a uranium mill tailings repository in South China by Azolla–Anabaena. The plant–microbe symbiont was kept in the effluent for 30 days, and it was found that U, Fe, Mn, Cu, Zn, Pb, Cd, total phosphorus (TP), total nitrogen (TN) and SO42? reduced by 87.6, 99.1, 98.8, 88.2, 91, 78.3, 77.5, 93.4, 98.7 and 76.7%, respectively. Specifically, the concentration of uranium reduced to 0.039 mg L?1, which is below the limits of contaminants by the Department of Environmental Protection of China. The concentration of Fe, Cu, Zn, Pb, TP and TN in the effluent reached the quality standard for drinking water. The results showed that Azolla–Anabaena can be used for the bioremediation of the effluent from the uranium mill tailings repository. 相似文献
28.
29.
30.
Spectral accuracy of molecular ions in an LTQ/Orbitrap mass spectrometer and implications for elemental composition determination 总被引:1,自引:0,他引:1
John C. L. Erve Ming Gu Yongdong Wang William DeMaio Rasmy E. Talaat 《Journal of the American Society for Mass Spectrometry》2009,20(11):2058-2069
In addition to mass accuracy, the ability of a mass spectrometer to faithfully measure the isotopic distribution of an ion,
defined as spectral accuracy, is also important. Although time-of-flight mass spectrometers are reported to possess high spectral
accuracy capability compared with other mass spectrometers, the Orbitrap has not yet been investigated. Ten natural products
(moxidectin, erythromycin, digoxin, rifampicin, amphotericin B, rapamycin, gramicidin S, cyclosporin A, vancomycin, and thiostrepton)
ranging in molecular weight from 639 to 1663 Da were measured on an LTQ/Orbitrap mass spectrometer with resolving power settings
of 7.5, 15, 30, 60, and 100 K. The difference in the observed profile isotope pattern compared with the theoretical calculation
after peak shape calibration, denoted spectral error, was calculated using the program MassWorks (Cerno Bioscience, Danbury,
CT, USA). Spectral errors were least at 7.5 K resolving power (≤3%) but exceeded 10% for some compounds at 100 K. The increasing
spectral error observed at higher resolving power for compounds with complex fine structure might be explained by the phenomena
of isotopic beat patterns as observed in FTICR. Several compounds with prominent doubly charged ions allowed comparison of
spectral accuracies of singly-versus doubly-charged ions. When using spectral error to rank elemental compositions with formula
constraints (C0–100H0–200N0–50O0–50Cl0–5S0–5) and a mass tolerance ≤2 parts-per-million, the correct formula was ranked first 35% of the time. However, spectral error
considerations eliminated >99% of possible elemental formulas for compounds with molecular weight >900 Da. 相似文献