全文获取类型
收费全文 | 353篇 |
免费 | 32篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 16篇 |
2020年 | 4篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 8篇 |
2015年 | 20篇 |
2014年 | 26篇 |
2013年 | 24篇 |
2012年 | 24篇 |
2011年 | 30篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 22篇 |
2006年 | 22篇 |
2005年 | 12篇 |
2004年 | 23篇 |
2003年 | 7篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1975年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1932年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 15 毫秒
1.
The probable effect of increasing levels of ammonium nitrogen on the growth, efficiency of nitrogen fixation, and main cellular constituents of Azotobacter vinelandii was studied under shaking and static culture conditions. The presence of NH4+-N up to 50 mgl-1 level has no harmful effect on the multiplication as well as the yield efficiency ratio of the tested organism. A. vinelandii was able to fix dinitrogen in the presence of NH4+-N when both nitrogen sources were available in the culturing medium. The efficiency of nitrogen fixation was affected by the initial presence of NH4+-N in the medium, it was quite low at the highest level. The crude protein efficiency ratio was correlated inversely with the initial NH4+-N concentration, whereas the total carbohydrate efficiency ratio as well as the total lipid efficiency ratio were positively correlated with the NH4+-N concentration. The presence of NH4+-N in the culturing medium has no essential influence on the qualitative composition of the amino acids in the Azotobacter cells. 相似文献
2.
3.
Dr. Sherif M. H. Sanad Alshimaa A. M. Abdelsalam Aya A. Gamal Eldin Esraa H. Abdelfattah Fatma R. M. Hussein Nada G. Mohammed Nariman A. S. Taha Prof. Dr. Ahmed E. M. Mekky 《化学与生物多样性》2023,20(6):e202300546
An efficient protocol was adopted to efficiently prepare three new series of bis(pyrazolo[1,5-a]pyrimidines) linked to different spacers. The new bis(pyrazolo[1,5-a]pyrimidines) were prepared in 80–90 % yields by reacting the respective bis(enaminones) and 4-(4-substituted benzyl)-1H-pyrazole-3,5-diamines in pyridine at reflux temperature for 5–7 h. The new products showed a wide spectrum of antibacterial activity against six different bacterial strains. In general, propane- and butane-linked bis(pyrazolo[1,5-a]pyrimidines), which are attached to 3-(4-methyl- or 4-methoxybenzyl) units, had the best antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values up to 2.5 and 5.1 μM, respectively. Additionally, the previous products demonstrated promising MurB inhibitory activity with IC50 values up to 7.2 μM. 相似文献
4.
M M Kader G Kamel M T Aziz M M Kenawy M M el-Sadani A Erfan K R Madwar N Sherif 《Acta biologica et medica Germanica》1975,34(9):1465-1469
Different blood lipid components were evaluated in obese and normal Egyptians. In obese, plasma levels of total lipoproteins, beta-lipoprotein, total cholesterol, triglycerides, and non-esterified fatty acids were found to be significantly elevated. The plasma levels of esterified cholesterol and phospholipids were found to be significantly reduced. Tertroxine caused a drop of the plasma level of total lipoproteins, beta lipoproteins and total cholesterol and rise of plasma level of non-esterified fatty acids. 相似文献
5.
Hassan A. Hemeg Ihab M. Moussa Sherin Ibrahim Turki M. Dawoud Jwaher H. Alhaji Ayman S. Mubarak Saleh A. Kabli Roua A. Alsubki Azza M. Tawfik Sherif A. Marouf 《Saudi Journal of Biological Sciences》2020,27(12):3221-3227
This study evaluates the antimicrobial effects of ethanolic extract of five herbal plants; Guava (Psidium guajava), Sage (Salvia officinalis), Rhamnus (Ziziphusspina Christi), Mulberry (Morusalba L.), and Olive (Oleaeuropaea L) leaves against several microbial population representing Gram positive, Gram negative and Mollicutes; S. aureus, E. coli, Pasteurella multocida, B. cereus, Salmonella Enteritidis and M. gallisepticum using standard agar disc diffusion technique and minimal inhibitory concentration (MIC). Different extracts reveal variable results against the microorganism under study. All extracts have no antibacterial potency for Mycoplasma gallisepticum except Psidium guajava. The results of minimal inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of the extracts against the six bacteria ranged from 625 to 5000 μg/ml. The used herbal extract could inhibit the selected microorganism under study with variable minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). 相似文献
6.
Baioumy Asmaa Ali Swelim Hamdy Hamed Ibrahim Ahmed Adly Mohamed Fatma El-Sayed Marzouk Aleya Soliman El-Alfy Sherif Helmy 《Experimental & applied acarology》2021,85(2-4):331-354
Experimental and Applied Acarology - This study examined the acaricidal, histopathological and genotoxic effects of the entomopathogenic fungus Beauveria bassiana on engorged females of the fowl... 相似文献
7.
8.
Yee?Him Cheung Tenzin Gayden Philippe?M. Campeau Charles?A. LeDuc Donna Russo Van-Hung Nguyen Jiancheng Guo Ming Qi Yanfang Guan Steffen Albrecht Brenda Moroz Karen?W. Eldin James?T. Lu Jeremy Schwartzentruber David Malkin Albert?M. Berghuis Sherif Emil Richard?A. Gibbs David?L. Burk Megan Vanstone Brendan?H. Lee David Orchard Kym?M. Boycott Wendy?K. Chung Nada Jabado 《American journal of human genetics》2013,92(6):996-1000
Infantile myofibromatosis (IM) is the most common benign fibrous tumor of soft tissues affecting young children. By using whole-exome sequencing, RNA sequencing, and targeted sequencing, we investigated germline and tumor DNA in individuals from four distinct families with the familial form of IM and in five simplex IM cases with no previous family history of this disease. We identified a germline mutation c.1681C>T (p.Arg561Cys) in platelet-derived growth factor receptor β (PDGFRB) in all 11 affected individuals with familial IM, although none of the five individuals with nonfamilial IM had mutations in this gene. We further identified a second heterozygous mutation in PDGFRB in two myofibromas from one of the affected familial cases, indicative of a potential second hit in this gene in the tumor. PDGFR-β promotes growth of mesenchymal cells, including blood vessels and smooth muscles, which are affected in IM. Our findings indicate p.Arg561Cys substitution in PDGFR-β as a cause of the dominant form of this disease. They provide a rationale for further investigations of this specific mutation and gene to assess the benefits of targeted therapies against PDGFR-β in aggressive life-threatening familial forms of the disease. 相似文献
9.
Sherif E. Hussein Osama A. Hassan Malcolm H. Granat 《Biomedical signal processing and control》2013,8(6):534-541
Alternative or complementary medicine emphasizes therapies that are claimed to improve quality of life, prevent disease, and address conditions that conventional medicine has limited success in curing. There are many techniques which are prevalent in many countries and these can cause harm if not scientifically evaluated. The objective of this paper is to validate the use of iridology to diagnose kidney abnormalities. Two subject groups were evaluated: one was 168 subjects free from kidney disease and the other was 172 subjects with chronic renal failure. The procedure to acquire, process and classify the iris images was designed in such a way that avoids any dependency on the iridologists by using wavelet analysis and Adaptive Neuro-Fuzzy Inference System. The results show a correct classification for both subjects with kidney problems and normal subjects of 82% and 93%, respectively. The proposed technique conducted on a systemic disease with ocular manifestations showed encouraging results. However, it is necessary to perform extensive studies with diseases that do not have ocular manifestations according to conventional medicine in order to validate iridology as a valid scientific technique. 相似文献
10.
Mohammed Sherif Debbie Waung Bihter Korbeci Valentina Mavisakalyan Robert Flick Greg Brown Mamdouh Abou‐Zaid Alexander F. Yakunin Emma R. Master 《Microbial biotechnology》2013,6(5):588-597
Multicopper oxidases can act on a broad spectrum of phenolic and non‐phenolic compounds. These enzymes include laccases, which are widely distributed in plants and fungi, and were more recently identified in bacteria. Here, we present the results of biochemical and mutational studies of small laccase (SLAC), a multicopper oxidase from Streptomyces coelicolor (SCO6712). In addition to typical laccase substrates, SLAC was tested using phenolic compounds that exhibit antioxidant activity. SLAC showed oxidase activity against 12 of 23 substrates tested, including caffeic acid, ferulic acid, resveratrol, quercetin, morin, kaempferol and myricetin. The kinetic parameters of SLAC were determined for 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid), 2,6‐dimethoxyphenol, quercetin, morin and myricetin, and maximum reaction rates were observed with myricetin, where kcat and Km values at 60°C were 8.1 (± 0.8) s?1 and 0.9 (± 0.3) mM respectively. SLAC had a broad pH optimum for activity (between pH 4 and 8) and temperature optimum at 60–70°C. It demonstrated remarkable thermostability with a half‐life of over 10 h at 80°C and over 7 h at 90°C. Site‐directed mutagenesis revealed 17 amino acid residues important for SLAC activity including the 10 His residues involved in copper coordination. Most notably, the Y229A and Y230A mutant proteins showed over 10‐fold increase in activity compared with the wild‐type SLAC, which was correlated to higher copper incorporation, while kinetic analyses with S929A predicts localization of this residue near the meta‐position of aromatic substrates. 相似文献