Severity: Warning
Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 176
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3122
Function: getPubMedXML
File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
A novel diethoxy phosphoryl chitosan was successfully synthesized via Atherton-Todd reaction of chitosan with diethyl phosphite, and the characterization was carried out by FT IR, NMR, ICP, XRD, TG and SEM, respectively. The FT IR, (13)C NMR and (31)P NMR results showed that diethoxy phosphoryl group was grafted onto the amino group of chitosan. XRD indicated that the incorporation of diethoxy phosphoryl group into chitosan increased the crystalline structure of the polymer. TG demonstrated that diethoxy phosphoryl chitosan was more thermal stable than chitosan. This simple and efficient synthetic method provides a new approach to the preparation of N-phosphoryl chitosan derivatives. And this new derivative of chitosan will open new perspectives as bio-functional material.
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Source |
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http://dx.doi.org/10.1016/j.ijbiomac.2010.06.014 | DOI Listing |
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