全文获取类型
收费全文 | 280篇 |
免费 | 12篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 17篇 |
2013年 | 24篇 |
2012年 | 29篇 |
2011年 | 17篇 |
2010年 | 24篇 |
2009年 | 10篇 |
2008年 | 15篇 |
2007年 | 21篇 |
2006年 | 12篇 |
2005年 | 21篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有292条查询结果,搜索用时 15 毫秒
101.
Some properties of immobilized alpha-amylase by Aspergillus sclerotiorum within calcium alginate gel beads were investigated and compared with soluble enzyme. Optimum pH and temperature were found to be 5.0 and 40 degrees C, respectively, for both soluble and immobilized enzymes. The immobilized enzyme had a better Km value, but kcat/Km values were the same for both enzymes. Entrapment within calcium alginate gel beads improved, remarkably, the thermal and storage stability of alpha-amylase. The half life values of immobilized enzyme and soluble enzyme at 60 degrees C were 164.2, and 26.2 min, respectively. The midpoint of thermal inactivation (Tm) shifted from 56 degrees C (for soluble enzyme) to 65.4 degrees C for immobilized enzyme. The percentages of soluble starch hydrolysis for soluble and immobilized alpha-amylase were determined to be 97.5 and 92.2% for 60 min, respectively. 相似文献
102.
Canan Aslan Nevin Çelebi İ. Tuncer Değim Ayşegül Atak Çiğdem Özer 《AAPS PharmSciTech》2017,18(4):1019-1030
The aim of this study was to develop and characterize rh- IL-2 loaded chitosan-based nanogels for the healing of wound incision in rats. Nanogels were prepared using chitosan and bovine serum albumin (BSA) by ionic gelation method and high temperature application, respectively. Particle size, zeta potential, and polydispersity index were measured for characterization of nanogels. The morphology of nanogels was examined by using SEM and AFM. The IL-2 loading capacity of nanogels was determined using ELISA method. In vitro release of IL-2 from nanogels was performed using Franz diffusion cells. Artificial neural network (ANN) models were developed using selected input parameters (stirring rate, chitosan%, BSA%, TPP%) where particle size was an output parameter for IL-2 free nanogels. Wound healing effect of IL-2 loaded chitosan-TPP nanogel was evaluated by determining the malondialdehyde (MDA) and glutathione (GSH) levels of wound tissues in rats. The particle size of IL-2 loaded chitosan-TPP nanogels was found to be larger than that of IL-2 loaded BSA-based chitosan nanogels. Drug loading capacity of nanogels was found 100%?±?0.010 for both nanogels. IL-2 was released slowly after the initial burst effect. According to SEM and AFM imaging, BSA-chitosan nanogel particles were of nanometer size and presented a swelling tendency, and chitosan-TPP nanogel particles were found to be spherical and homogenously dispersed. IL-2 loaded chitosan-TPP nanogel was found suitable for improving wound healing because it decreased the MDA levels and increased the GSH levels wound tissues comparing to control group. 相似文献
103.
Canan Uluoglu Ugur Hodoglugil H. Zafer Gü ney C. Zafer G rgü n Nurettin Abacioglu Hakan Zengil 《Biological Rhythm Research》1998,29(4):343-352
The presence of temporal patterns in the responses of vascular smooth muscle to relaxing agents have been known. The aim of this study was to examine the variations in the in vitro sensitivity of rat aorta to papaverine and theophylline in both endothelium-intact and -denuded rings. The animals were synchronized with a 12-h light: 12-h dark schedule. Rat thoracic aorta rings were obtained from animals sacrificed at six different times (09:00, 13:00, 17:00, 21:00, 01:00 and 05:00) of the day. Tissues were precontracted submaximally with phenylephrine and then were relaxed by papaverine (10-8 - 10-4 M) and theophylline (10-7 &miknus; 10-3 M) applied cumulatively. The responses to most of the concentrations and EC50 values for papaverine demonstrated an ultradian rhythm with an 8 h periodicity. Time-dependent variations were not found in the responses to theophylline. The results are discussed in relation with the time-dependent differences in signal transducing mechanisms. 相似文献
104.
Caroline J. Ross Ali Rana Atilgan Özlem Tastan Bishop Canan Atilgan 《Biophysical journal》2018,114(4):822-838
Enterovirus 71 can be a severe pathogen in small children and immunocompromised adults. Virus uncoating is a critical step in the infection of the host cell; however, the mechanisms that control this process remain poorly understood. We applied normal mode analysis and perturbation response scanning to several complexes of the virus capsid and present a coarse-graining approach to analyze the full capsid. We show that our method offers an alternative to expressing the system as a set of rigid blocks and accounts for the interconnection between nodes within each subunit and protein interfaces across the capsid. In our coarse-grained approach, the modes associated with capsid expansion are captured in the first three nondegenerate modes and correspond to the changes observed in structural studies of the virus. We show that the resolution of the analysis may be modified without losing information on the global motions leading to uncoating. Perturbation response scanning revealed that a protomer cannot serve as a functional unit to explain deformations of the capsid. Instead, we define a pentamer as the minimum functional unit to investigate changes within the capsid. From the modal analysis and perturbation response scanning, we locate a hotspot region surrounding the fivefold axis. The range of the effect of these single, hotspot residues extend to 140 Å. The perturbation of internal capsid residues in this region displayed greatest propensity to capsid expansion, thus indicating the significant role that the RNA genome may play in triggering uncoating. 相似文献
105.
Adrian Butt Claudia Mousley Karl Morris Jim Beynon Canan Can Eric Holub Jean T. Greenberg Vicky Buchanan-Wollaston 《The Plant journal : for cell and molecular biology》1998,16(2):209-221
The metallothionein gene, LSC54 , shows increased expression during leaf senescence in Brassica napus and Arabidopsis thaliana . A number of abiotic and biotic stresses have been shown to induce senescence-like symptoms in plants and, to investigate this further, the promoter of the LSC54 gene was cloned and fused to the GUS gene and transformed into Arabidopsis . The promoter was highly induced during leaf senescence and also in response to wounding; histochemical analysis indicated that this induction was localised to a few cells close to the wound site. The transgenic Arabidopsis tissue was infected with compatible and incompatible isolates of both the fungal biotroph, Peronospora parasitica and the bacterial necrotroph, Pseudomonas syringae. Incompatible isolates induced rapid cell death (the hypersensitive response) at the site of infection and, with both pathogens, early, localised expression of the GUS gene was observed. In contrast, relatively slow induction of the GUS gene was seen in the compatible interaction and this was correlated with the appearance of senescence-like symptoms in the biotrophic interaction and cell death by necrosis that occurred in response to the necrotrophic pathogen. These results suggest that there are common steps in the signalling pathways that lead to cell death in the hypersensitive response, pathogen induced necrosis and senescence. 相似文献
106.
Inhibition of alpha-glucosidase by aqueous extracts of some potent antidiabetic medicinal herbs 总被引:6,自引:0,他引:6
Diabetes mellitus is one of the most prevalant diseases of adults. Agents with alpha-glucosidase inhibitory activity have been useful as oral hypoglycemic drugs for the control of hyperglycemia in patients with type 2; noninsulin-dependent, diabetes mellitus (NIDDM). Investigation of some medicinal herbs: Urtica dioica, Taraxacum officinale, Viscum album, and Myrtus communis with alpha-glucosidase inhibitor activity was conducted to identify a prophylactic effect for diabetes in vitro. All plants showed differing potent alpha-glucosidase inhibitory activity. However, Myrtus communis strongly inhibited the enzyme (IC50 = 38 microg/mL). The inhibitory effect of these plants and some common antidiabetic drugs against the enzyme source (baker's yeast, rabbit liver, and small intestine) were also searched. Approximately all inhibitors used in this study showed quite different inhibitory activities, according to alpha-glucosidase origins. Furthermore, subsequent separation of the active material from Myrtus communis by HPLC showed that only one fraction acted as an a-glucosidase inhibitor. 相似文献
107.
Zinc-deficient sprouting blight potatoes and their possible relation with neural tube defects 总被引:2,自引:0,他引:2
Maternal nutritional zinc deficiency is blamed in the pathogenesis of neural tube defects. In animal and plant domains zinc is required for growth and development. The objective of the present study was to show that sprouting blighted potato tuber is zinc deficient. In five potato varieties, zinc was measured by atomic absorption spectrophotometry in wet-ashed paired slices of edible potato tuber and in its peel, in blighted potato tuber and in its sprout. Zinc contents were measured as the mean (+/- SEM) and the following values were found, 0.388 +/- 0.036, 0.623 +/- 0.059, 0.550 +/- 0.030 and 1.089 +/- 0.181 mg per 100 g wet weight, respectively. In conclusion, we believe that long-term consumption of zinc-depleted, blight potato tuber by pregnant woman could be potentially teratogenic with the consequent birth of a baby with neural tube defects. 相似文献
108.
109.
Ayhan-Kilcigil G Kuş C Coban T Can-Eke B Ozbey S Iscan M 《Journal of enzyme inhibition and medicinal chemistry》2005,20(5):503-514
The synthesis and antioxidant evaluation of some novel benzimidazole derivatives (10-24) are described. Antioxidant properties of the compounds were investigated employing various in vitro systems viz., microsomal NADPH-dependent inhibition of lipid peroxidation (LP), interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and scavenging of superoxide anion radical. Compounds 12 and 13 showed very good antioxidant capacity and were 17-18-fold more potent than BHT (IC50 2.3 x 10(-4) M) with 1.3 x 10(-5) M and 1.2 x 10(-5) M IC50 values, respectively, by interaction of the stable DPPH free radical. 相似文献
110.
Tekin M Akcayoz D Ucar C Gulen H Akar N 《Human biology; an international record of research》2005,77(3):393-397
The 657del5 mutation of the NBS1 gene has been demonstrated in most patients with Nijmegen breakage syndrome (NBS). We identified four Turkish families in which probands were diagnosed as having NBS and found to be homozygous for the 657del5 mutation. The 657del5 allele in the four Turkish families had a single origin. 相似文献