全文获取类型
收费全文 | 104篇 |
免费 | 5篇 |
专业分类
化学 | 81篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 4篇 |
物理学 | 20篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2002年 | 4篇 |
2000年 | 2篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 15 毫秒
41.
42.
ABSTRACT: BACKGROUND: Peptide: N glycanase (PNG) enzyme cleaves oligosaccharides from the misfolded glycoproteins and prepares them for degradation. This enzyme plays a role in the endoplasmic reticulum associated degradation (ERAD) pathway in yeast and mice but its biological importance and role in multicellular development remain largely unknown. RESULTS: In this study, the PNG from the cellular slime mold, Dictyostelium discoideum (DdPNG) was identified based on the presence of a common TG (transglutaminase) core domain and its sequence homology with the known PNGs. The domain architecture and the sequence comparison validated the presence of probable functional domains in DdPNG. The tertiary structure matched with the mouse PNG. Here we show that DdPNG is an essential protein, required for aggregation during multicellular development and a knock out strain of it results in small sized aggregates, all of which do not form fruiting bodies. The in situ hybridization and RT PCR results show higher level of expression during the aggregate stage. The expression gets restricted to the prestalk region during later developmental stages. DdPNG is a functional peptide-N-glycanase enzyme possessing deglycosylation activity, but does not possess any significant transamidation activity. CONCLUSIONS: We have identified and characterized a novel PNG from D. discoideum and confirmed its deglycosylation activity. The results emphasize the importance of PNG in aggregation during multicellular development of this organism. 相似文献
43.
We present rapid synthesis of gold nanoparticles by microwave irradiation method. Sample with average particle size 7.7 nm is obtained from TEM. Linear and nonlinear optical studies of the prepared samples are discussed. Reverse saturable absorption (RSA) at longitudinal surface plasmon resonance (SPR) in gold nanoparticles (Au NPs) have been observed using Z-scan and transient absorption techniques with 532 nm laser pulses. Such RSA behavior makes Au NPs an ideal candidate for optical limiting applications. 相似文献
44.
Anju Chopra Dheer Singh R. Manna S. Saravanan M. I. S. Sastry M. B. Patel B. Basu 《Chromatographia》2014,77(11-12):845-851
A GC and IR based protocol was developed for monitoring the isobutene dimerisation process wherein the complete characterisation of the products was carried out by GC coupled with mass spectrometry. In the dimerisation process, LPG from FCC process comprising a mixture of saturated and unsaturated C4 hydrocarbons is subjected to a dimerisation process using a catalyst to produce C8 hydrocarbons. The reaction is carried out keeping in view the demand for high-octane blending components in gasoline. The isooctene generated in the process (mainly from the dimerisation of isobutene) is converted into isooctane having the RON and MON value 100. The monitoring process requires the use of two different column chemistries, viz., a 100 m CPSIL PONA CB non-polar column for C8 and its isomers and an Alumina PLOT column for C4 hydrocarbons. A 100 m non-polar column does not separate the C4 mixture since the column is meant for gasoline range products containing C5 and above hydrocarbons. Therefore, a need was felt for an improvised method which can handle both the analyses simultaneously. A cryogenic oven program starting from 0 °C was developed for separating the isomers of C4 hydrocarbons and C8 hydrocarbons on a single column during the single run by Detailed Hydrocarbon Analyzer. The data obtained using the cryo programme was validated with data obtained using Alumina PLOT column on C4 mixture since the Alumina PLOT column is the widely accepted column chemistry for separating the C4 hydrocarbons. An IR method for the estimation of the total olefin content was developed using 2,2,4-trimethyl pentene-1 as the reference standard. The total olefins generated during the process were identified by GC–MS, quantified by DHA-FID and validated by infrared spectroscopy. A good correlation was found between GC and IR spectral results (correlation coefficient R 2 = 0.99). 相似文献
45.
Anju Gupta 《Proceedings Mathematical Sciences》1993,103(3):257-267
Ramanujan's last gift to the mathematicians was his ingeneous discovery of the mock theta functions of order three, five and seven. Recently, Andrews and Hickerson found a set of seven more functions in Ramanujan's Lost Note Book and formally labelled them as mock theta functions of order six. In this paper the complete forms of these functions have been studied and connected with the bilateral basic hypergeometric series2Ψ2. Several other interesting properties and transformations have also been studied. 相似文献
46.
Line strengthsS for the dipole allowed transitions within then=2 complex of the oxygen isoelectronic sequence have been fitted in the formZ
2
S=A+B/(Z −C), whereZ is the nuclear charge of a particular ion. The constantsA, B andC are determined by using a non-linear least square method. The data forS are taken from the configuration interaction calculations which included internal, semi-internal and all external type correlations
for ions in the rangeZ=8 − 25. It is shown that the values ofA obtained from the fit for all the transitions are in excellent accord with the ab-initio values obtained in the hydrogenic
limitZ → ∞ provided near degeneracy effects are included in the ground state multiplet 1s22s22p4
1S. 相似文献
47.
Activity-guided fractionation of the ethanolic extract of the leaves of the Polyalthia longifolia var. pendula led to the identification of quercetin (1), quercetin-3-O-β-glucopyranoside (2), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-galactopyranoside (3), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-glucopyranoside (4), rutin (5) and allantoin (6) as the active constituents from the butanol fraction. Compounds 2-4 are reported for the first time from this natural source. Structures of the compounds were confirmed on the basis of their 1D and 2D NMR coupled with other spectroscopic methods. All the isolated compounds and the fractions were evaluated for their antioxidant potential using the TEAC assays and it was found that the activity of the active fraction was due to quercetin (1) and its glycosides (2 and 5), with TEAC values of 4.10, 1.91 and 2.38 mM, respectively, while the kaempferol glycosides were found to be inactive. This is the first study on the antioxidant activity of this plant species. 相似文献
48.
Wai Peng Lee Alberto Martinez Dan Xu Anju Brooker David W. York Yulong Ding 《Particuology》2009,7(6):459-465
This work aims to understand the effect of nanoparticle-enzyme interactions and how such interactions affect starch based soil removal. Silica and laponite are used as the model nanoparticles, and s-amylase is employed as the model enzyme. The results show that, if the nanoparticles and enzyme are added simultaneously, laponite enhances the enzyme performance toward starch soil removal, whereas silica imposes a small effect on the enzymatic activity towards the same soil substrates. However, when nanoparticles are added first, the enzyme activity is not affected much by laponite but is hindered significantly by silica nanoparticles. Furthermore, sequential addition of the enzyme followed by silica nanoparticles improves soil removal. Electron microscopic analyses, measurements of the enzyme activity in suspen- sions of nanoparticles, and particle size characterisation suggest that dense coverage of soil surface by the silica nanoparticles be likely a mechanism for the experimentally observed hindrance of soil removal when silica nanoparticles are added before enzyme. 相似文献
49.
Gishamol Mathew Anju Babu Jesly Jacob Vincent Mathew 《Superlattices and Microstructures》2008,44(2):203-207
This paper discusses the magneto-optic phase shift in garnet/semiconductor-on-insulator plasmonic waveguides. We consider two structures: (1) Y IG/Si/SiO2 and (2) Y IG/GaInAsP/AlInAs-oxide. A dispersion relation for the plasmon propagation has been derived and the nonreciprocal phase shift of the fundamental TM mode has been determined at wavelengths of 1.55 μm, 1.5 μm and 1.3 μm. 相似文献