全文获取类型
收费全文 | 135篇 |
免费 | 9篇 |
国内免费 | 5篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 4篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1968年 | 1篇 |
1966年 | 2篇 |
1947年 | 1篇 |
1937年 | 1篇 |
1930年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有149条查询结果,搜索用时 15 毫秒
1.
Suren A. Tatulian 《生物化学与生物物理学报:生物膜》1983,736(2):189-195
Temperature dependence of the electrophoretic mobility of multilamellar liposomes prepared from dimyristoylphosphatidylcholine was measured in the presence of salts with different anions in aqueous solutions. It was established that specific binding of anions to liposome surface induced a pronounced zeta potential (electrostatic potential at the hydrodynamic plane of shear). A combination of Langmuir, Gouy-Chapman, and Boltzmann equations was used to describe the dependence of the zeta potential on the concentration of anions. The values of binding constants (K) and maximum numbers of binding sites per unit area (σmax) were determined by this method. The sequence for anion affinities to liposome surface was found to be as follows: trinitrophenol >ClO4− >I− >SCN− >Br− >NO3− >Cl− SO42−. A sharp increase in the negative zeta potential was detected at the temperature of phase transition of the lipid from the gel to liquid-crystalline state. It was found that the parameter K did not change at lipid phase transition and the shifts in zeta potential might be due to alterations of σmax. The binding sites were considered as defects in the package of lipid molecules in membranes. 相似文献
2.
3.
4.
Soghomonyan S Hajitou A Rangel R Trepel M Pasqualini R Arap W Gelovani JG Alauddin MM 《Nature protocols》2007,2(2):416-423
Non-invasive imaging of transgene expression requires the appropriate combination of a reporter gene and a reporter probe. [18F]FEAU positron emission tomography (PET) is used for the assessment of herpes simplex virus type-1 thymidine kinase gene expression. Hybrid AAV phage (termed AAVP) can be adapted to transduce mammalian cells by targeting to a specific receptor. We evaluated a targeted AAVP vector using [18F]FEAU PET. This protocol describes [18F]FEAU production and dosing, micro-PET imaging and image analysis. 2-Deoxy-2-trifluoromethanesulfonyl-1,3,5-tri-O-benzoyl-alpha-D-ribofuranose is radio-fluorinated, converted into its 1-bromo derivative and coupled with protected 5-ethyl uracil. The coupled product is hydrolyzed and purified using HPLC. Tumor-bearing animals targeted with either retroviral or AAVP vectors are anesthetized and injected with [18F]FEAU (0.1 mCi per mouse); this is followed 2 h after injection by imaging on a micro-PET. Production of [18F]FEAU requires approximately 3.5 h from the end of bombardment. PET imaging studies require 2-3 h (depending on the number of animals) after synthesis of [18F]FEAU. 相似文献
5.
Structural effects of covalent inhibition of phospholipase A2 suggest allosteric coupling between membrane binding and catalytic sites
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tatulian SA 《Biophysical journal》2003,84(3):1773-1783
Phospholipase A(2) (PLA(2)) binds to membranes and catalyzes phospholipid hydrolysis, thus initiating the biosynthesis of lipid-derived mediators of inflammation. A snake-venom PLA(2) was completely inhibited by covalent modification of the catalytic histidine 48 by p-bromophenacyl bromide. Moreover, His(48) modification affected PLA(2) structure, its membrane-binding affinity, and the effects of PLA(2) on the membrane structure. The native PLA(2) increased the order parameter of fluid membranes, whereas the opposite effect was observed for gel-state membranes. The data suggest membrane dehydration by PLA(2) and the formation of PLA(2)-membrane hydrogen bonding. The inhibited PLA(2) had lower membrane-binding affinity and exerted weaker effects on membrane hydration and on the lipid-order parameter. Although membrane binding resulted in formation of more flexible alpha-helices in the native PLA(2), which corresponds to faster amide hydrogen exchange, the modified enzyme was more resistant to hydrogen exchange and experienced little structural change upon membrane binding. The data suggest that 1), modification of a catalytic residue of PLA(2) induces conformational changes that propagate to the membrane-binding surface through an allosteric mechanism; 2), the native PLA(2) acquires more dynamic properties during interfacial activation via membrane binding; and 3), the global conformation of the inhibited PLA(2), including the alpha-helices, is less stable and is not influenced by membrane binding. These findings provide further evidence for an allosteric coupling between the membrane-binding (regulatory) site and the catalytic center of PLA(2), which contributes to the interfacial activation of the enzyme. 相似文献
6.
7.
8.
The thermostability of the endo-beta-1,4-xylanase from Thermomyces lanuginosus (xynA) was improved by directed evolution using error-prone PCR. Transformants expressing the variant xylanases were first selected on 0.4% Remazol Brilliant Blue-xylan and then exposed to 80 degrees C. Whereas the wild type XynA lost 90% activity after 10 min at 80 degrees C, five mutants displayed both higher stabilities and activities than XynA. Four mutants were subjected to further mutagenesis to improve the stability and activity of the xylanase. Subsequent screening revealed three mutants with enhanced thermostability. Mutant 2B7-10 retained 71% of its activity after treatment at 80 degrees C for 60 min and had a half-life of 215 min at 70 degrees C, which is higher than that attained by XynA. Sequence analysis of second generation mutants revealed that mutations were not concentrated in any particular region of the protein and exhibited much variation. The best mutant obtained from this study was variant 2B7-10, which had a single substitution (Y58F) in beta-sheet A of the protein, which is the hydrophilic, solvent-accessible outer surface of the enzyme. Most of the mutants obtained in this study displayed a compromise between stability and activity, the only exception being mutant 2B7-10. This variant showed increased activity and thermostability. 相似文献
9.
Rutland CS Polo-Parada L Ehler E Alibhai A Thorpe A Suren S Emes RD Patel B Loughna S 《Development (Cambridge, England)》2011,138(18):3955-3966
The expression and function of embryonic myosin heavy chain (eMYH) has not been investigated within the early developing heart. This is despite the knowledge that other structural proteins, such as alpha and beta myosin heavy chains and cardiac alpha actin, play crucial roles in atrial septal development and cardiac function. Most cases of atrial septal defects and cardiomyopathy are not associated with a known causative gene, suggesting that further analysis into candidate genes is required. Expression studies localised eMYH in the developing chick heart. eMYH knockdown was achieved using morpholinos in a temporal manner and functional studies were carried out using electrical and calcium signalling methodologies. Knockdown in the early embryo led to abnormal atrial septal development and heart enlargement. Intriguingly, action potentials of the eMYH knockdown hearts were abnormal in comparison with the alpha and beta myosin heavy chain knockdowns and controls. Although myofibrillogenesis appeared normal, in knockdown hearts the tissue integrity was affected owing to apparent focal points of myocyte loss and an increase in cell death. An expression profile of human skeletal myosin heavy chain genes suggests that human myosin heavy chain 3 is the functional homologue of the chick eMYH gene. These data provide compelling evidence that eMYH plays a crucial role in important processes in the early developing heart and, hence, is a candidate causative gene for atrial septal defects and cardiomyopathy. 相似文献
10.
Perin EC Tian M Marini FC Silva GV Zheng Y Baimbridge F Quan X Fernandes MR Gahremanpour A Young D Paolillo V Mukhopadhyay U Borne AT Uthamanthil R Brammer D Jackson J Decker WK Najjar AM Thomas MW Volgin A Rabinovich B Soghomonyan S Jeong HJ Rios JM Steiner D Robinson S Mawlawi O Pan T Stafford J Kundra V Li C Alauddin MM Willerson JT Shpall E Gelovani JG 《PloS one》2011,6(9):e22949
The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, repetitive PET/CT imaging with [(18)F]FEAU to monitor the long-term (up to 5 months) spatial-temporal dynamics of MSCs retrovirally transduced with the sr39HSV1-tk gene (sr39HSV1-tk-MSC) and implanted intramyocardially in pigs with induced acute myocardial infarction. Repetitive [(18)F]FEAU PET/CT revealed a biphasic pattern of sr39HSV1-tk-MSC dynamics; cell proliferation peaked at 33-35 days after injection, in periinfarct regions and the major cardiac lymphatic vessels and lymph nodes. The sr39HSV1-tk-MSC-associated [(18)F]FEAU signals gradually decreased thereafter. Cardiac lymphography studies using PG-Gd-NIRF813 contrast for MRI and near-infrared fluorescence imaging showed rapid clearance of the contrast from the site of intramyocardial injection through the subepicardial lymphatic network into the lymphatic vessels and periaortic lymph nodes. Immunohistochemical analysis of cardiac tissue obtained at 35 and 150 days demonstrated several types of sr39HSV1-tk expressing cells, including fibro-myoblasts, lymphovascular cells, and microvascular and arterial endothelium. In summary, this study demonstrated the feasibility and sensitivity of [(18)F]FEAU PET/CT imaging for long-term, in-vivo monitoring (up to 5 months) of the fate of intramyocardially injected sr39HSV1-tk-MSC cells. Intramyocardially transplanted MSCs appear to integrate into the lymphatic endothelium and may help improve myocardial lymphatic system function after MI. 相似文献