全文获取类型
收费全文 | 270篇 |
免费 | 22篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 15篇 |
2011年 | 18篇 |
2010年 | 19篇 |
2009年 | 10篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 14篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 6篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有292条查询结果,搜索用时 7 毫秒
1.
Purification of low density lipoprotein receptor from liver and its quantification by anti-receptor monoclonal antibodies. 下载免费PDF全文
The low density lipoprotein (LDL) receptor has been purified to homogeneity from rabbit liver by a combination of DEAE-Sephacel chromatography, LDL-Sepharose 4B chromatography and preparative SDS/polyacrylamide-gel electrophoresis. The receptor protein had a pI of 4.45 and an Mr of 120 x 10(3)-125 x 10(3) in SDS gels under non-reducing conditions. Incubation of the LDL receptor with neuraminidase decreased its Mr to 105 x 10(3)-110 x 10(3) and increased its pI from 4.45 to 5.25. The purified receptor exhibited all the properties of the membrane-bound receptor including Ca2+-dependent binding of rabbit and human LDL but not of methylated LDL or high density lipoprotein. The amount of LDL receptor present in rabbit liver was measured by a quantitative blotting procedure employing a newly developed rat anti-receptor monoclonal antibody. The affinity and specificity of this monoclonal antibody allowed the quantification of the LDL receptor in detergent extracts of liver homogenate, thus eliminating the loss of receptor associated with the preparation of membrane fractions prior to receptor assay. Livers from adult female New Zealand White rabbits contained 149 +/- 13 ng of LDL receptor/mg of liver protein. Administration of pharmacological doses of 17 alpha-ethinyloestradiol raised the concentration of LDL receptor in liver to 312 +/- 25 ng/mg of liver protein. 相似文献
2.
Francesca Gherardi 《Journal of Ethology》1996,14(2):111-121
In the hermit crabClibanarius signatus, the influence of both shell status and social context on agonistic behavior was examined. The experimental hermits were
of the same size and sex, but differed in the status of the inhabited shell, which was either optimal, sub-optimal or damaged.
The evidence from this experiment suggests that the agonistic behavior ofC. signatus is influenced to a great extent by asymmetries in the resource value; attacks are mainly performed by crabs which inhabit
shells in a relatively poor condition and are mostly directed towards opponents with better-fitting shells. However, this
effect differs according to the social context, being more pronounced when the potential gain is greater. Shell fights are
decidedly more complex than most animal combats; more work is certainly needed to understand the mechanisms underlying resource
assessment and decisions made during hermit crabs' interactions. 相似文献
3.
Francesca Gherardi Federica Tarducci Marco Vannini 《Ethology : formerly Zeitschrift fur Tierpsychologie》1988,77(4):300-316
Locomotor activity in a field population of the freshwater crab, Potamon fluviatile, was studied during the breeding season by means of radio-telemetry and by direct counts of active animals along a transect of the stream. The basic pattern of crabs' locomotor activity can be described as a sequence of short distance movements around the shelters (foraging movements), followed by rarer long distance displacements (wandering movements). Whilst direct counting showed that the crabs exhibit a broadly nocturnal rhythm in foraging movements, no daily periodicity in wandering activity was revealed by telemetry. There is sexual difference in these latter excursions: females move farther along the stream and into the surrounding terrestrial habitat than do males. This behaviour is in contrast to observations made during the non-breeding season and is probably related to the stage of female reproduction. 相似文献
4.
Structural repertoire of the human VH segments. 总被引:16,自引:0,他引:16
C Chothia A M Lesk E Gherardi I M Tomlinson G Walter J D Marks M B Llewelyn G Winter 《Journal of molecular biology》1992,227(3):799-817
The VH gene segments produce the part of the VH domains of antibodies that contains the first two hypervariable regions. The sequences of 83 human VH segments with open reading frames, from several individuals, are currently known. It has been shown that these sequences are likely to form a high proportion of the total human repertoire and that an individual's gene repertoire produces about 50 VH segments with different protein sequences. In this paper we present a structural analysis of the amino acid sequences produced by the 83 segments. Particular residue patterns in the sequences of V domains imply particular main-chain conformations, canonical structures, for the hypervariable regions. We show that, in almost all cases, the residue patterns in the VH segments imply that the first hypervariable regions have one of three different canonical structures and that the second hypervariable regions have one of five different canonical structures. The different observed combinations of the canonical structures in the first and second regions means that almost all sequences have one of seven main-chain folds. We describe, in outline, structures of the antigen binding site loops produced by nearly all the VH segments. The exact specificity of the loops is produced by (1) sequence differences in their surface residues, particularly at sites near the centre of the combining site, and (2) sequence differences in the hypervariable and framework regions that modulate the relative positions of the loops. 相似文献
5.
Regulation of cell movement: the motogenic cytokines 总被引:16,自引:0,他引:16
6.
In a survey of blood genetic markers in the Niokolonko of Eastern Senegal, three types of G6PD variants were discovered: (1) fast variants, common Negro G6PD A +; the frequency of the Gd A + gene was 0.183; (2) deficient G6PD A--, occurring with a fairly low frequency: 0.079, and (3) some individuals were carriers of a slow moving electrophoretic variant with normal activity. After purification, the analysis of kinetic parameters showed that this enzyme was closely similar to G6PD Tacoma. We proposed to label it 'G6PD Tacoma-like'. The incidence of this mutation in the whole group studied was 0.020. G6PD Tacoma-like may be common in some African tribes. 相似文献
7.
Matteo Gelardi Alfredo Vizzini Enrico Ercole Samuele Voyron Gang Wu Xing-Zhong Liu 《Mycological Progress》2013,12(3):575-588
Strobilomyces echinocephalus Gelardi & Vizzini sp. nov. is described as a new species, based on collections from Kunming (Yunnan Province, China). Macro-morphological and micro-morphological features, ecological data and analyses of RPB1 and ITS2 sequences support the establishment of this new taxon. Colour pictures of fresh basidiomata in habitat, scanning electron microscope (SEM) micro-photographs of the spores, and a line-drawing displaying the most relevant anatomical characters are provided in this paper. Strobilomyces zangii Gelardi nom. nov. is proposed to replace the name Heimiella nigricans M. Zang. A dichotomous key to the Strobilomyces species at global level is also provided at the end of this work. 相似文献
8.
Gabriela Turk Yanina Ghiglione Juliana Falivene María Eugenia Socias Natalia Laufer Romina Soledad Coloccini Ana María Rodriguez María Julia Ruiz María ángeles Pando Luis David Giavedoni Pedro Cahn Omar Sued Horacio Salomon María Magdalena Gherardi 《Journal of virology》2013,87(13):7445-7462
The important role of the CD8+ T-cell response on HIV control is well established. Moreover, the acute phase of infection represents a proper scenario to delineate the antiviral cellular functions that best correlate with control. Here, multiple functional aspects (specificity, ex vivo viral inhibitory activity [VIA] and polyfunctionality) of the HIV-specific CD8+ T-cell subset arising early after infection, and their association with disease progression markers, were examined. Blood samples from 44 subjects recruited within 6 months from infection (primary HIV infection [PHI] group), 16 chronically infected subjects, 11 elite controllers (EC), and 10 healthy donors were obtained. Results indicated that, although Nef dominated the anti-HIV response during acute/early infection, a higher proportion of early anti-Gag T cells correlated with delayed progression. Polyfunctional HIV-specific CD8+ T cells were detected at early time points but did not associate with virus control. Conversely, higher CD4+ T-cell set points were observed in PHI subjects with higher HIV-specific CD8+ T-cell VIA at baseline. Importantly, VIA levels correlated with the magnitude of the anti-Gag cellular response. The advantage of Gag-specific cells may result from their enhanced ability to mediate lysis of infected cells (evidenced by a higher capacity to degranulate and to mediate VIA) and to simultaneously produce IFN-γ. Finally, Gag immunodominance was associated with elevated plasma levels of interleukin 2 (IL-2) and macrophage inflammatory protein 1β (MIP-1β). All together, this study underscores the importance of CD8+ T-cell specificity in the improved control of disease progression, which was related to the capacity of Gag-specific cells to mediate both lytic and nonlytic antiviral mechanisms at early time points postinfection. 相似文献
9.
Gabriella Guerrini Giovanna Ciciani Samuele Ciattini Letizia Crocetti Simona Daniele Claudia Martini 《Journal of enzyme inhibition and medicinal chemistry》2016,31(2):195-204
To investigate the binding affinity of GABAA receptor subtype, new pyrazolo [1,5-a]quinazolines were designed, synthesized, and in vitro evaluated. These compounds, 5-deaza analogues of pyrazolo[5,1-c][1,2,4]benzotriazine derivatives which were already studied in our research group, permit us to evaluate the relevance of the nitrogen or the oxygen atom at 5-position of the tricyclic scaffold. Molecular dynamic study was done on a set of the new and known ligands to rationalize and to explain the lack of affinity on the 4- or 5-substituted new derivative. In fact, from biological results, it can be found that the only 5-unsubstituted new derivative, compound 15, has receptor recognition (Ki?=?834.7?nM). 相似文献
10.
Samuele Lodovichi Martina Vitello Tiziana Cervelli 《Cell cycle (Georgetown, Tex.)》2016,15(20):2723-2731
BRCA1 tumor suppressor gene is found mutated in familial breast and ovarian cancer. Most cancer related mutations were found located at the RING (Really Interesting New Gene) and at the BRCT (BRca1 C-Terminal) domain. However, 20 y after its identification, the biological role of BRCA1 and which domains are more relevant for tumor suppression are still being elucidated. We previously reported that expression of BRCA1 cancer related variants in the RING and BRCT domain increases spontaneous homologous recombination in yeast indicating that BRCA1 may interact with yeast DNA repair/recombination. To finally demonstrate whether BRCA1 interacts with yeast DNA repair, we exposed yeast cells expressing BRCA1wt, the cancer-related variants C-61G and M1775R to different doses of the alkylating agent methyl methane-sulfonate (MMS) and then evaluated the effect on survival and homologous recombination. Cells expressing BRCA1 cancer variants were more sensitive to MMS and less inducible to recombination as compared to cell expressing BRCA1wt. Moreover, BRCA1-C61G and -M1775R did not change their nuclear localization form as compared to the BRCA1wt or the neutral variant R1751Q indicating a difference in the DNA damage processing. We propose a model where BRCA1 cancer variants interact with the DNA double strand break repair pathways producing DNA recombination intermediates, that maybe less repairable and decrease MMS-induced recombination and survival. Again, this study strengthens the use of yeast as model system to characterize the mechanisms leading to cancer in humans carrying the BRCA1 missense variant. 相似文献