全文获取类型
收费全文 | 246篇 |
免费 | 7篇 |
国内免费 | 42篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 13篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 16篇 |
2004年 | 20篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有295条查询结果,搜索用时 93 毫秒
1.
N A Kocharova Iu A Knirel' N K Kochetkov E S Stanislavski? 《Bioorganicheskaia khimiia》1988,14(5):701-703
A polysaccharide isolated from the degraded lipopolysaccharides of P. aeruginosa serogroup O7 (Lányi--Bergan classification) was characterized by liquid chromatography, acid hydrolysis, and 1H and 13C NMR spectroscopy. It has molecular mass 15,000 and represents mainly a rhamnan of the structure----2)-alpha-D-Rha-(1----3)-alpha-D-Rha-(1----3)-alpha-D-Rha-(1 ----, identical to the structure of O-specific polysaccharides of Pseudomonas aeruginosa pvs morsprunorum and cerasi. Some minor constituents, such as glucose, mannose, an unknown sugar, and phosphate, are found in the polysaccharide preparation as well. Distribution of the rhamnan in some other P. aeruginosa serogroups is discussed and its identity to the common polysaccharide antigen of P. aeruginosa is suggested. 相似文献
2.
Structure of an extracellular cross-reactive polysaccharide from Pseudomonas aeruginosa immunotype 4 总被引:6,自引:0,他引:6
N A Kocharova Y A Knirel A S Shashkov N K Kochetkov G B Pier 《The Journal of biological chemistry》1988,263(23):11291-11295
A neutral small molecular mass (approximately 6.5 kDa) polysaccharide comprising a pentasaccharide repeat unit was isolated from culture supernatants of Pseudomonas aeruginosa immunotype 4. The polysaccharide had a pentasaccharide repeating unit as follows (formula; see text) where Rha is rhamnose. The structure was determined using acid hydrolysis, solvolysis with anhydrous hydrogen fluoride, methylation analysis, and 1H and 13C nuclear magnetic resonance spectroscopy including nuclear Overhauser enhancement experiments. The polysaccharide bound antibody raised to the lipopolysaccharide of the seven P. aeruginosa Fisher-Devlin immunotype strains. Inhibition assays demonstrated the presence of a serologically similar polysaccharide in supernatants of these strains. Affinity-purified antibody to the polysaccharide bound to lipopolysaccharide and whole cells of the immunotype strains of P. aeruginosa in a Western immunoblot and colony blot assay, respectively. This polysaccharide seems to contain an antigenic determinant present in the core of the P. aeruginosa lipopolysaccharide or may represent another minor polysaccharide substituent on the lipopolysaccharide in addition to the O side chain. 相似文献
3.
I U Knirel' N A Kocharova A S Shashkov L D Varbanets N K Kochetkov 《Bioorganicheskaia khimiia》1986,12(9):1268-1273
O-Specific polysaccharide composed of L-rhamnose and 2-acetamido-2-deoxy-D-mannose was obtained on mild acid degradation of P. aeruginosa X (Meitert classification) lipopolysaccharide. On the basis of non-destructive analis using 1H, 13C NMR spectroscopy and Klyne's rule calculation, as well as chemical methods (acid hydrolysis, methylation, Smith degradation), it was established that the polysaccharide is built up of disaccharide repeating units of the following structure: ----4)-alpha-L-Rha-(1----3)-beta-D-ManNAc-(1----. 相似文献
4.
34Fusarium graminearum Schw isolates produced 4-deoxynivalenol to form significant amounts of 4, 7 — dideoxynivalenol and lesser amounts of 4 — deoxynivalenol monoacetates on grain substratesin vitro. This is the first report on the capability a large group of naturally occurring isolates to produce 4,7-dideoxynivalenol. The average levels of 4,7-dideoxynivalenol on rice, corn, barley, and wheat as a substrate were respectively 26.8, 14.0, 12.8, and 10.5% of the level of 4-deoxynivalenol. 4, 7 — dideoxynivalenol was present in all examined naturally contaminated wheat kernel samples at levels of 1.7 to 7.9% of the level of 4-deoxynivalenol. These findings suggest that more attention should be given to the occurrence of 4,7-dideoxynivalenol in cereals. 相似文献
5.
Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex 总被引:1,自引:0,他引:1
The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S
nuclear ribosomal DNA sequence and the intervening 5.8S region were
sequenced from three individuals in each of eight taxa of the Mimulus
guttatus species complex. Three discrete variants, or "types," of ITS
sequences were found, among which 30%-40% of sites differed, compared with
1%-2% within types. Dot plots indicate that these types were not related by
conspicuous rearrangements or inversions. More than one ITS type was often
found in the same taxon, and two of three ITS types span species
boundaries, indicating their presence prior to speciation. These ITS
sequences showed essentially no positional homology with the nearest
sequenced relative, tomato. In contrast, the 5.8S region was relatively
unvaried, with 8 of 162 sites varied in the sample among all eight taxa.
The phylogeny inferred by the most common ITS sequence type, rooted by the
two other ITS types, agreed with isozymes in showing the distinctness of M.
nudatus, M. laciniatus, and M. tilingii from the other five taxa.
相似文献
6.
7.
报道了小菇科小菇属真菌10个中国新记录种,香菌组:橙盖小菇Mycena aurantiidisca、黄白小菇Mycena flavoalba、粉黄小菇Mycena floridula;棘刺组:异刺小菇Mycena heteracantha;纤柄组:碱味小菇Mycena amygdalina;脆足组:粉被小菇Mycena zephirus;冬生组:绣线菊小菇Mycena speirea、冬生小菇Mycena hiemalis;小菇组:绒柄小菇Mycena flos-nivium,分别来自吉林等11个省份、自治区。提供了每个物种的形态描述和线条图,以及与相近种的讨论。共计90条自测及下载ITS序列,在采用贝叶斯法和最大似然法构建的小菇属系统发育树中,新记录种均得到分子数据支持。凭证标本存放于吉林农业大学菌物标本馆(HMJAU)。 相似文献
8.
9.
本文通过Aβ25-35诱导体外原代培养的SD乳大鼠海马神经元,建立Aβ毒性损伤细胞模型,结合AnnexinV-FITC/PI荧光双染法流式细胞术、MTT比色法、实时荧光定量PCR及Western blot方法检测川芎嗪(tetrameth-ylpyrazine,TMP)对原代培养的海马神经元细胞活性、早期凋亡率和Bax、Bcl-2基因表达的影响。结果显示川芎嗪高、中剂量可明显增强细胞活性,增加神经元细胞的存活率(P<0.01),可显著抑制海马神经元细胞早期凋亡(P<0.01),抑制凋亡蛋白Bax的表达(P<0.01),增强抗凋亡蛋白bcl-2的表达(P<0.01)。川芎嗪可通过调节Bax/Bcl-2平衡抵抗Aβ25-35诱导的海马神经元凋亡,降低Aβ的神经元毒性,对海马神经元损伤有明显的保护作用。 相似文献
10.