全文获取类型
收费全文 | 245篇 |
免费 | 11篇 |
专业分类
256篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 11篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 18篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 18篇 |
2012年 | 17篇 |
2011年 | 10篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1968年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有256条查询结果,搜索用时 12 毫秒
61.
Monoclonal antibodies (Mabs) against human chorionic gonadotropin hormone (hCG) were raised by hybridoma technology using Sp2/0 myeloma cells as fusion partner. Sixty-five percent of the total culture wells exhibited hybrid growth and 8% of the total wells (13 culture wells) contained anti-hCG secreting hybrids. A positive hybrid cell line secreting antibodies against the free alpha-subunit of hCG was cloned twice by limiting dilution method and eighty four clones were obtained that secreted monoclonal antibodies anti-alpha hCG. One of these hybridoma clones (1C4) secreting monoclonal antibodies against the free alpha-subunit of hCG was selected for purification and characterization purposes. This hybridoma cell line secreted monoclonal antibodies of IgG1 subclass, which were purified by affinity chromatography on Protein A Sepharose CL-4B column with a final relative recovery of antibody activity of 75% and a purification factor of about 12. The purified preparation was analyzed by SDS-PAGE, native PAGE, and IEF. Specificity studies of this Mab revealed that it recognized specifically an epitope on the free alpha-subunits of hCG, FSH, LH, and TSH as determined by enzyme immunoassays. On the other hand, this Mab exhibited crossreactivity with other pituitary hormones either as free subunits or intact molecules as follows: alpha hCG 100%; intact hCG 1.8%; beta hCG 0.14%; alpha FSH 24.5%; intact FSH 0.8%; beta FSH 0.09%; alpha LH 20.5%; intact LH 0.9%; beta LH 0.08%; alpha TSH 50.5%; intact TSH 3.7%; beta TSH 0.07%; The affinity constant (K) of this Mab with respect to free alpha-subunit of hCG was found to be 1.5 x 10(7) I/mol as determined by the simple antibody dilution analysis method. 相似文献
62.
63.
José Lino Costa Isabel Domingos Carlos A. Assis Pedro R. Almeida Francisco Moreira Eric Feunteun Maria José Costa 《Environmental Biology of Fishes》2008,81(4):421-434
A total of 1,816 eels were sampled in 1988, from seven sampling areas. Four areas were located in brackish water and the remaining
three were located in freshwater reaches of the Tagus river basin. Eels were more abundant in the middle estuary and decreased
both in the upstream and in the downstream directions, with a predominance of males in higher density areas. Smaller individuals
preferred more peripheral areas, such as margins and upper reaches in the brackish water zone, and the tributaries of the
freshwater habitats. It was assumed that this distribution pattern resulted from three main factors: (i) the dominance of
larger specimens; (ii) the need to avoid predators and; (iii) the search for better trophic conditions. The condition of the
individuals generally decreased toward the upper reaches, apparently due to a corresponding decrease in feeding intensity.
The presence of the Belver dam in the main river, 158 km upstream from the sea, seemed to impose major alterations to the
described patterns. The concentration of specimens below this impassable obstacle yielded a reduction in the proportion of
females and a decrease in the condition and survival of the eels, contributing to a reduction in the spawning success of this
population. Suggestions to diminish the effects of the dam, and to preserve the fishery are also presented. 相似文献
64.
Detoni CB de Oliveira DM Santo IE Pedro AS El-Bacha R da Silva Velozo E Ferreira D Sarmento B de Magalhães Cabral-Albuquerque EC 《Journal of liposome research》2012,22(1):1-7
Zanthoxylum tinguassuiba essential oil (ZtEO) contains α-bisabolol, a known antiglioma sesquiterpene, among other potentially active substances. Medical applications of this essential oil require advances in the design of distinctive carriers due to its low water solubility and easy degradation by heat, light, and oxygen. The aim of this work was to evaluate enhancement in oxidative stability and the ability to reduce glioblastoma cell viability of ZtEO loaded into liposomes. Multi- and unilamellar vesicles were prepared to carry ZtEO. By using thermal analysis, it was observed that thermal-oxidative stability of the liposomal ZtEO was enhanced, when compared to its free form. Liposomal ZtEO also presented significant apoptotic-inducing activity for glioma cells. These results show that liposomal systems carrying ZtEO may be a potential alternative for gliobastoma treatment. 相似文献
65.
66.
Noldin VF de Oliveira Martins DT Marcello CM da Silva Lima JC Delle Monache F Cechinel Filho V 《Zeitschrift für Naturforschung. C, Journal of biosciences》2005,60(9-10):701-706
Simaba ferruginea (Simaroubaceae) is a Brazilian medicinal plant used in traditional medicine to treat several ailments, including gastric ulcers, fever, diarrhea, and dolorous and inflammatory processes. This study examines the chemical composition and antiulcerogenic effects of rhizomes from this plant. Bioassay-guided fractionation led to the isolation of two bioactive indole alkaloids called canthin-6-one (1) and 4-methoxycanthin-6-one (2). The alkaloid fraction and both alkaloids demonstrated potent antiulcerogenic effects when evaluated in gastric lesion-induced animals, as well as significant antinociceptive activity in mice. These results confirm and justify the popular use of S. ferruginea against gastric ulcers and dolorous processes. 相似文献
67.
Vinícius R. Campos Paula A. Abreu Helena C. Castro Carlos R. Rodrigues Alessandro K. Jordo Vitor F. Ferreira Maria C.B.V. de Souza Fernanda da C. Santos Laura A. Moura Thaisa S. Domingos Carla Carvalho Eldio F. Sanchez Andr L. Fuly Anna C. Cunha 《Bioorganic & medicinal chemistry》2009,17(21):7429-7434
The current treatment used against envenomation by Lachesis muta venom still presents several side effects. This paper describes the synthesis, pharmacological and theoretical evaluations of new 1-arylsulfonylamino-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl esters (8a–f) tested against the hemolytic profile of the L. muta snake venom. Their structures were elucidated by one- and two-dimensional NMR techniques (1H, APT, HETCOR 1JCH and nJCH, n = 2, 3) and high-resolution electrospray ionization mass spectrometry. The series of triazole derivatives significantly neutralized the hemolysis induced by L. muta crude venom presenting a dose-dependent inhibitory profile (IC50 = 30−83 μM) with 1-(4′-chlorophenylsulfonylamino)-5-methyl-1H-[1,2,3]-triazole-4-carboxylic acid ethyl ester (8e) being the most potent compound. The theoretical evaluation revealed the correlation of the antiophidian profile with the coefficient distribution and density map of the Highest Occupied Molecular Orbitals (HOMO) of these molecules. The elucidation of this new series may help on designing new and more efficient antiophidian molecules. 相似文献
68.
69.
Domingos Cardoso Luciano P. de Queiroz R. Toby Pennington Haroldo C. de Lima Émile Fonty Martin F. Wojciechowski Matt Lavin 《American journal of botany》2012,99(12):1991-2013
• Premise of study: Phylogenetic relationships of the papilionoid legumes (Papilionoideae) reveal that the early branches are more highly diverse in floral morphology than are other clades of Papilionoideae. This study attempts for the first time to comprehensively sample the early-branching clades of this economically and ecologically important legume subfamily and thus to resolve relationships among them. • Methods: Parsimony and Bayesian phylogenetic analyses of the plastid matK and trnL intron sequences included 29 genera not yet sampled in matK phylogenies of the Papilionoideae, 11 of which were sampled for DNA sequence data for the first time. • Key results: The comprehensively sampled matK phylogeny better resolved the deep-branching relationships and increased support for many clades within Papilionoideae. The potentially earliest-branching papilionoid clade does not include any genus traditionally assigned to tribe Swartzieae. Dipterygeae is monophyletic with the inclusion of Monopteryx. The genera Aldina and Amphimas represent two of the nine main but as yet unresolved lineages comprising the large 50-kb inversion clade within papilionoids. The quinolizidine-alkaloid-accumulating genistoid clade is expanded to include a strongly supported subclade containing Ormosia and the previously unplaced Clathrotropis s.s., Panurea, and Spirotropis. Camoensia is the first-branching genus of the core genistoids. • Conclusions: The well-resolved phylogeny of the earliest-branching papilionoids generated in this study will greatly facilitate the efforts to redefine and stabilize the classification of this legume subfamily. Many key floral traits did not often predict phylogenetic relationships, so comparative studies on floral evolution and plant–animal interactions, for example, should also benefit from this study. 相似文献
70.
Regional differences in the surface temperature of Naked Neck laying hens in a semi-arid environment 总被引:1,自引:0,他引:1
João Batista Freire de Souza Jr Alex Martins Varela de Arruda Hérica Girlane Tertulino Domingos Leonardo Lelis de Macedo Costa 《International journal of biometeorology》2013,57(3):377-380
The aim of this study was to evaluate the regional differences in the surface temperature of Naked Neck hens that were subjected to different temperatures in a semi-arid environment. The surface temperature was measured in four body regions (face, neck, legs and feathered area) of 60 Naked Neck hens. The following environmental variables were measured at the center of the shed: the black globe temperature (T G ), air temperature (T A ), wind speed (U) and relative humidity (R H ). The T A was divided into three classes: 1 (24.0–26.0 °C), 2 (26.1–28.9 °C) and 3 (29.0–31.0 °C). An analysis of variance was performed by the least squares method and a comparison of the means by the Tukey-Kramer test. The results showed a significant effect of T A class, the body region and the interaction between these two effects on the surface temperature. There was no significant difference between the T A classes for the face and neck. The legs and feathered area showed significant differences between the T A classes. Regarding the effect of body regions within each T A class, there was a significant difference among all regions in the three T A classes. In all T A classes the neck had the highest average followed by the face and legs. The feathered area showed the lowest average of the different T A classes. In conclusion, this study showed that there are regional differences in the surface temperature of Naked Neck hens, with the legs acting as thermal windows. 相似文献