全文获取类型
收费全文 | 364篇 |
免费 | 14篇 |
国内免费 | 1篇 |
出版年
2022年 | 7篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 20篇 |
2014年 | 17篇 |
2013年 | 28篇 |
2012年 | 24篇 |
2011年 | 18篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 14篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有379条查询结果,搜索用时 398 毫秒
371.
In this study we determined that Aspergillus tamarii Kita is able to utilize Avena sativa L. (oats) for the production of β-xylosidase under static or shaking conditions in submerged liquid-state (LSF), solid-state (SSF) and slurry-state (SlSF) cultures. The produced enzyme was purified and characterized. Maximum yield occurred under shaking conditions in SSF cultures (33.7 U/ml), with 24.9 and 5.5 U/ml produced in SISF and LSF cultures, respectively. Peptone was found to be the best nitrogen additive and enhanced enzyme production (41.5 U/ml). The produced enzyme was precipitated by ammonium sulfate (60 %) and further purified by gel filtration through a Sephadex G-100 and ion exchange column of diethylaminoethyl cellulose, with a yield of 40.57 % and 35.73-fold purification. Enzyme activity was optimal at pH 5.5 and 55 °C. The purified enzyme retained full activity even at the end of a 1-h incubation at this optimal condition. Midpoint of thermal inactivation (Tm) was recorded at 60 °C after 90 min of exposure. The Michaelis–Menten constant, maximal reaction velocity, turnover number and specificity constant of the purified enzyme were calculated to be 0.075 mg/ml, 71.42 U/mg of protein, 7.14/S and 95.2 mg/ml/s, respectively. The inability of the purified enzyme to hydrolyze celluloses indicated that the enzyme was a free cellulase. The most efficient enzyme activators were Mg2+, followed by Mn2+ and Zn2+ in that order. The molecular mass of the purified enzyme was 91 kDa as determined by SDS-PAGE. The possibility of using the fermentation of ground oat hydrolysate for the production of ethanol and xylitol in the presence of Pichia stipitis Pignal was assessed. The maximum production of ethanol and xylitol were obtained after 72 h of fermentation, resulting in 11.06 and 21.51 g/l respectively. 相似文献
372.
373.
Ahmed M.T. Mohamed Helena Chan Johana Luhur Elda Bauda Benoit Gallet Cécile Morlot Louise Cole Milena Awad Simon Crawford Dena Lyras David Z. Rudner Christopher D.A. Rodrigues 《Developmental cell》2021,56(1):36-51.e5
- Download : Download high-res image (133KB)
- Download : Download full-size image
374.
S S Awad J D Welty A R al-Muhailan 《Comparative biochemistry and physiology. A, Comparative physiology》1991,98(2):175-178
1. Comparisons of the effects of 4 and 16 weeks of exercise were made on; cardiac output, stroke volume, heart rate, left intraventricular systolic and diastolic pressures, dP/dt, and heart calcium in the Bio 14.6 cardiomyopathic and F1 B hamsters. 2. In the cardiomyopathic hamster the cardiac output, stroke volume, left intraventricular systolic pressure and dP/dt, which were all depressed in the age related sedentary animals, were increased by both periods of exercise. The left intraventricular diastolic pressure which was elevated was likewise decreased by both exercise periods. Only the 16 week exercise period decreased the resting heart rate. 3. In the normal F1 B hamster, both periods of exercise increased the cardiac output and stroke volume while the left intraventricular systolic pressure was decreased. Only the 16 week exercise decreased the resting heart rate and left intraventricular diastolic pressure and increased the left ventricular dP/dt. 4. Both periods of exercise increased the total heart calcium in the Bio 14.6 hamster while the heart calcium in the F1 B was increased only by the 16 week exercise period. 相似文献
375.
376.
Vitthal Awad Rohit Shirke Sourav Mukherjee Suresh Khadke Pankaj Pawar Nilambika Meti Abhay Harsulkar 《In vitro cellular & developmental biology. Plant》2011,47(4):525-535
Taverniera cuneifolia (Roth) Arn. or Indian licorice is considered to be a substitute for Glycyrrhiza glabra L. owing to an equivalent content of glycyrrhizic acid (GA). GA recognized as the main active ingredient of T. cuneifolia, GA imparts several medicinal properties to these plants. However, research on this plant is scanty with no published record
on tissue culture studies. Present study demonstrates a method for (1) induction and successful development of somatic embryos
from the root culture, (2) regeneration of plants, and (3) GA production by root cultures of T. cuneifolia. Shoot initiation frequency of cultured roots ranged from 52.57% to 97.71%. Plant regeneration frequency (germination) from
somatic embryos was 88.66% in 1/4-strength Murashige and Skoog (MS) medium supplemented with 2% sucrose, as against 68% in
half 1/2-strength MS containing 2% sucrose. Glycyrrhizic acid of 1.32 mg/gm of dry weight was obtained in full-strength MS
medium supplemented with 3% sucrose, through high-performance thin layer chromatography analysis with standard GA in root
cultures. The present study provides an efficient method for the mass production of plants from a single mother plant as well
as the potential root culture system to study the GA production pathways in T. cuneifolia. 相似文献
377.
Hemat S. Khalaf Hala E. M. Tolan Mohamed A. A. Radwan Ashraf M. Mohamed Hanem M. Awad Wael A. El-Sayed 《Nucleosides, nucleotides & nucleic acids》2020,39(7):1036-1056
AbstractNew 1,3,4-thiadiazole thioglycosides linked to substituted pyrimidines were synthesized via glycosylation of 1,3,4-thiadiazole thiol compounds. Also, novel 1,2,3-triazole derivatives linked to carbohydrate units were prepared using the standard click chemistry conditions employing the Cu(I)-catalyzed azide-alkyne cycloaddition of substituted-aryl-azides with a selection of alkyne-functionalized sugars. The chemical structures of the new derivatives were verified using various spectroscopic techniques, such as IR, 1H NMR, 13C NMR and elemental analyses. The cytotoxic activities of the prepared compounds were investigated in vitro against human liver cancer (HepG-2) and human breast adenocarcinoma (MCF7) cell lines. In addition, the biological evaluation of the new compounds involved the investigation of their effects on a human normal retinal pigmented epithelial cell line (RPE1) using the MTT assay. 相似文献
378.
Sulaiman Ali Alharbi Milton Wainwright Tahani Awad Alahmadi Hashim Bin Salleeh Asmaa A. Faden Arunachalam Chinnathambi 《Saudi Journal of Biological Sciences》2014,21(4):289-293
What would have happened had Alexander Fleming not discovered penicillin in 1928? Perhaps the obvious answer is that, someone else would have discovered penicillin during 1930s and the Oxford group, would still have purified it sometime in the early 1940s. Here, however, in this counterfactual account of the penicillin story, it is argued that without Fleming, penicillin might still be undiscovered and the antibiotic age would never have dawned. As a result, many of the recent developments in medicine, such as organ transplantation, might have been delayed or, at best, made more hazardous. Penicillin might have come onto the scene a few years later but, had Fleming overlooked the discovery, it seems certain that penicillin would not have saved countless Allied lives, during and after D-Day. Instead of having enjoyed fifty and more years of the antibiotic age, it is argued here, that we would have had to rely upon highly developed sulphonamides, so-called “supasulfas”, and other chemically-derived antibacterial drugs. Indeed, it might be the case that, even well into this new millennium, the antibiotic age has yet to dawn, and medicine is still waiting for someone to chance upon penicillin. Here we discuss what might have happened had Fleming not discovered penicillin and come to the conclusion that the medical armoury available today would have been far different and might have relied solely upon highly developed varieties of sulphonamides or similar, synthetic, non-antibiotic antibacterial agents. 相似文献
379.