全文获取类型
收费全文 | 138篇 |
免费 | 3篇 |
专业分类
141篇 |
出版年
2021年 | 4篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2015年 | 5篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 5篇 |
2007年 | 2篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1973年 | 1篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1964年 | 1篇 |
1962年 | 2篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1952年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 15 毫秒
71.
Polarized light microscopy in the study of the molecular structure of collagen and reticulin 总被引:2,自引:0,他引:2
Although collagen structure has been studied by polarized light microscopy since the early 19th century and continued since, modern studies and reviews failed to correlate the conclusions based on data obtained by the techniques with those of polarized light microscopy. Collagen I is intensely positively birefringent in respect to length of the fibres; the positive intrinsic birefringence indicates a quasi-crystalline alignment parallel to the fibre and molecule axis of the amino acid residues of the polypeptide chains. This would not have been compatible with a helical structure but has been achieved by similar tilt angles and opposite directions of the coiling and supercoiling. Birefringence characteristics of collagen are also affected by chemical treatments, extractions and staining procedures. Attachment of chemical groups to the anionic charges present on the surface of collagen molecules results in increased positive birefringence in the case of bipolar molecules attached to two or more anionic residues. Unipolar attachment to the same groups, or to the cationic groups of the associated proteoglycans, as well as sulfation or acetylation of hydroxyls of the protein and/or the carbohydrate, reduced or reversed the sign of birefringence. Increased birefringence caused by stretching cannot be due to intramolecular events and is caused by intermolecular changes. The same applies to changes in collagen during aging. Reticulin is a group of different substances which mostly contain collagen III. The pliability and deformability of this collagen is related to its weakly negative birefringence due to large side chains and presence of different and greater amounts of interstitial proteoglycans and other molecules. The so-called reticulin of healing wounds differs in its constitution from other reticulins but is also rich in intermolecular carbohydrate components. 相似文献
72.
M Wolman 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1987,25(2):109-114
It is a short survey of lipid pigment formation in which the role of free radicals in the peroxidation of lipids is particularly stressed. The chemical structure of lipopigments and the role of the chemical moiety in histochemical reactions is shortly overviewed. A new aspect of age in the formation of lipopigments is brought to light. Finally the role of hypoxaemia and no-reflow phenomenon influencing the pigment formation is discussed. 相似文献
73.
A process based on orally-infected Rachiplusia nu larvae as biological factories for expression and one-step purification of horseradish peroxidase isozyme C (HRP-C) is described.
The process allows obtaining high levels of pure HRP-C by membrane chromatography purification. The introduction of the partial polyhedrin homology sequence element in the target gene increased HRP-C expression level by 2.8-fold whereas it increased 1.8-fold when the larvae were
reared at 27°C instead of at 24°C, summing up a 4.6-fold overall increase in the expression level. Additionally, HRP-C purification
by membrane chromatography at a high flow rate greatly increase D the productivity without affecting the resolution. The Vmax and Km values of the recombinant HRP-C were similar to those of the HRP from Armoracia rusticana roots. 相似文献
74.
Maria R. Wing Wei Yang Valerie Teal Sankar Navaneethan Kaixiang Tao Akinlolu Ojo Nicolas N. Guzman Muredach Reilly Melanie Wolman Sylvia E. Rosas Magda Cuevas Michael Fischer Eva Lustigova Stephen R. Master Dawei Xie Dina Appleby Marshall Joffe John Kusek Harold I Feldman Dominic S. Raj for the Chronic Renal Insufficiency Cohort Study 《Obesity (Silver Spring, Md.)》2014,22(5):1359-1366
75.
76.
Basil Wolman 《BMJ (Clinical research ed.)》1962,1(5292):1591-1592
77.
Esophageal cancer involves multiple genetic alternations. A systematic codon usage bias analysis was completed to investigate the bias among the esophageal cancer responsive genes. GC-rich genes were low (average effective number of codon value was 49.28). CAG and GTA are over-represented and under-represented codons, respectively. Correspondence analysis, neutrality plot, and parity rule 2 plot analysis confirmed the dominance over mutation pressure in modulating the codon usage pattern of genes linked with esophageal cancer. 相似文献
78.
79.
80.
D B Gregson D E Low M M Cohen N B Cooter J J Connon S L Wolman A E Simor 《CMAJ》1989,140(12):1449-1453
To determine the prevalence of Campylobacter pylori colonization in the healthy population we studied 54 asymptomatic volunteers and 65 patients referred because of gastrointestinal symptoms. All subjects underwent gastroscopy and gastric biopsy. C. pylori was isolated from 6 volunteers (11%) and 36 patients (55%). Histologic evidence of inflammation was present in 98% of the culture-positive subjects. Linear regression analysis revealed that the prevalence of C. pylori colonization increased with age. There was no difference in the isolation rate between the two groups when adjusted for age. Four of the six culture-positive volunteers underwent repeat endoscopy and gastric biopsy 1 year later; despite remaining asymptomatic, all still had positive culture results and histologic evidence of gastritis. We conclude that the prevalence of C. pylori-associated gastritis among symptomatic patients increases with age and that the organism may be present in the gastrointestinal tract for prolonged periods without symptoms or evidence of disease progression. 相似文献