全文获取类型
收费全文 | 80篇 |
免费 | 10篇 |
专业分类
90篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 1篇 |
2015年 | 8篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1874年 | 1篇 |
排序方式: 共有90条查询结果,搜索用时 0 毫秒
81.
Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
82.
83.
Veena?DhawanEmail author SS?Handu Chandra?Kanwal?Nain Nirmal?Kumar?Ganguly 《Molecular and cellular biochemistry》2005,269(1):1-11
Chronic exposure to l-arginine results in regression of atherosclerotic lesions and reversal of endothelial dysfunction. We investigated whether chronic l-arginine supplementation induces regression of atherosclerotic lesions and reversal of endothelial dysfunction in atherogenic rhesus monkeys and the mechanism which leads to these effects. About 12 male rhesus monkeys were fed 1% cholesterol and 18 g butter for 6 months to create an experimental model of hypercholesterolaemia and atherosclerosis (Group I) and 12 monkeys were fed standard stock diet for 6 months (Group II). After, 6 months these two groups were further divided into 2 sub-groups which in addition to their respective diets were fed 2.5% l-arginine in drinking water for additional 6 months (Group III and Group IV). Systemic nitric oxide (NO) formation was assessed as plasma nitrite and cGMP formation every 3 months. Oxygen free radical (OFR) generation and malondialdehyde production as an index of lipid peroxidation were determined. Changes in isometric tension were compared in isolated ring segments of thoracic aorta from normal and hypercholesterolemic animals.Cholesterol feeding progressively reduced plasma nitrite and cGMP generation (p<0.05). Dietary l-arginine partly restored the levels of plasma nitrite and cGMP (p<0.05) but did not change plasma cholesterol levels. l-arginine significantly reduced aortic intimal thickening, blocked the production of carotid and coronary intimal plaques and completely preserved endothelium-dependent vasodilator function. Further, l-arginine significantly inhibited generation of the reactive oxygen species (ROS) generation and lipid peroxidation.Chronic oral supplementation with l-arginine blocks the progression of plaques via restoration of nitric oxide synthase substrate availability and reduction of vascular oxidative stress. (Mol Cell Biochem 269: 1–11, 2005) 相似文献
84.
Ishaku A. Gazali A. M. Abdullahi S. A. Hussaini N. 《Journal of mathematical biology》2020,81(1):209-241
Journal of Mathematical Biology - A non-linear mechanistic model for the transmission dynamics of HIV/AIDS is developed and analyzed. The model classified the infected individuals based on their... 相似文献
85.
Isoquinoline derived alkaloids from Berberis chitria 总被引:1,自引:0,他引:1
A new aporphine base characterized as O-methylcorydine-N-oxide together with berberine, palmatine, jatrorrhizine and oxyacanthine has been isolated from Berberis chitria. 相似文献
86.
87.
Iron-histidine resonance raman band of deoxyheme proteins: effects of anharmonic coupling and glass-liquid phase transition 下载免费PDF全文
Weak anharmonic coupling of two soft molecular vibrations is shown to cause pronounced temperature dependence of the corresponding resonance Raman bands. The developed theory is used to interpret the temperature dependence of the iron-histidine band of deoxyheme proteins and model compounds. It is shown that anharmonic coupling of the iron-histidine and heme doming vibrations must cause pronounced broadening of the band, its asymmetry, and shift of its maximum to the red upon heating. It also can lead to a structured shape of this band at room temperature. Proper consideration of the anharmonic coupling allows simulation of the temperature dependence of the iron-histidine band shape of horse heart myoglobin in the temperature interval of 10-300 K, using the minimum number of necessary parameters. Analysis of this temperature dependence clearly shows that the iron-histidine band of deoxyheme proteins is sensitive to the glass-liquid phase transition in the protein hydration shell, which takes place at 160-190 K. 相似文献
88.
Raiees Andrabi Rajesh Kumar Manju Bala Ambili Nair Prakash SS Vandana Kushwaha Kalpana Luthra 《Journal of microbiology (Seoul, Korea)》2012,50(5):869-873
Subtypes of human immunodeficiency virus type 1 circulating in 21 north Indian patients were characterized based on the partial sequence of the gp120 envelope protein. A majority of viruses (85.7%, 18/21) were subtype C, while 14.3% (3/21) were subtype A. Sequence analysis revealed that the V3 region was highly conserved compared with V4 and V5. The predicted use of co-receptors indicated exclusive usage of R5, except for two subtype A viruses (AIIMS279 and AIIMS281). Our results demonstrate conservation within the V3 loop of subtype C viruses, and suggest the emergence of non-clade C viruses in the north Indian population. 相似文献
89.
Vishnu J Ram Navedul Haque Mahendra Nath Sunil K Singh Falak A Hussaini S.C Tripathi A Shoeb 《Bioorganic & medicinal chemistry letters》1997,7(24):247-3152
The synthesis and hepatoprotective activity of 6-aryl-3-substituted-4-methylthio-2H-pyran-2-ones (3, 5, 7) and the corresponding 2-thiones (6), 6-aryl-4-methylthio-2H-pyran-2-ones (4) and 6-aryl-3-carbethoxy-5-cyano-4-methylthio-2H-pyran-2-ones are described. 相似文献
90.