全文获取类型
收费全文 | 187篇 |
免费 | 13篇 |
专业分类
200篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2019年 | 2篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 7篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 2篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 1篇 |
1979年 | 11篇 |
1978年 | 14篇 |
1977年 | 6篇 |
1975年 | 1篇 |
1974年 | 8篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有200条查询结果,搜索用时 15 毫秒
191.
192.
Using hexokinase and malate dehydrogenase as genetic markers, it was found that Ceratina calcarata and C. dupla interbred only occasionally in nature where they were sympatric. Therefore, they should be considered as two bona fide species, even though females are morphologically identical. 相似文献
193.
Nianbai Fang Shanggong Yu Martin JJ Ronis Thomas M Badger 《Experimental biology and medicine (Maywood, N.J.)》2015,240(4):488-497
High-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are generally accepted as the preferred techniques for detecting and quantitating analytes of interest in biological matrices on the basis of the rule that one chemical compound yields one LC-peak with reliable retention time (Rt.). However, in the current study, we have found that under the same LC-MS conditions, the Rt. and shape of LC-peaks of bile acids in urine samples from animals fed dissimilar diets differed significantly among each other. To verify this matrix effect, 17 authentic bile acid standards were dissolved in pure methanol or in methanol containing extracts of urine from pigs consuming either breast milk or infant formula and analyzed by LC-MS/MS. The matrix components in urine from piglets fed formula significantly reduced the LC-peak Rt. and areas of bile acids. This is the first characterization of this matrix effect on Rt. in the literature. Moreover, the matrix effect resulted in an unexpected LC behavior: one single compound yielded two LC-peaks, which broke the rule of one LC-peak for one compound. The three bile acid standards which exhibited this unconventional LC behavior were chenodeoxycholic acid, deoxycholic acid, and glycocholic acid. One possible explanation for this effect is that some matrix components may have loosely bonded to analytes, which changed the time analytes were retained on a chromatography column and interfered with the ionization of analytes in the MS ion source to alter the peak area. This study indicates that a comprehensive understanding of matrix effects is needed towards improving the use of HPLC and LC-MS/MS techniques for qualitative and quantitative analyses of analytes in pharmacokinetics, proteomics/metabolomics, drug development, and sports drug testing, especially when LC-MS/MS data are analyzed by automation software where identification of an analyte is based on its exact molecular weight and Rt. 相似文献
194.
Schistosoma mansoni: identification, characterization, and purification of the spine glycoprotein by monoclonal antibody 总被引:4,自引:0,他引:4
A tegumental surface membrane antigen of Schistosoma mansoni has been identified by use of a monoclonal antibody. The binding of 125I-labeled monoclonal antibody showed that proteins sharing antigenic determinants recognized by this monoclonal antibody were present in cercariae and worms of both sexes, but were absent from schistosome egg extract. The protein molecules expressing these antigenic determinants differed in molecular weight: 120,000 in cercaria and 170,000 in male and female worms. The cercarial glycoprotein immunoprecipitated with the monoclonal antibody was also immunoprecipited by sera of infected humans, as shown by two-dimensional gel electrophoresis and tryptic peptide mapping. The location of the glycoprotein identified by the monoclonal antibody was restricted to the spines of the schistosomular surface, the tubercle-associated spines of the male worm, and the dorsal spines of the female worm. The spine glycoprotein was readily purified by immunoaffinity chromatography. These findings are discussed in relation to parasite development and the relevance of this antibody for serodiagnosis and immunoprophylaxis. 相似文献
195.
196.
197.
198.
199.
Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component. 相似文献
200.