全文获取类型
收费全文 | 96篇 |
免费 | 6篇 |
专业分类
102篇 |
出版年
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1922年 | 1篇 |
排序方式: 共有102条查询结果,搜索用时 15 毫秒
1.
乙型肝炎病毒X蛋白HBx与肝细胞癌的发生有很高的相关性。PCR扩增并克隆了HBx基因及其失活突变体HBx-M13。构建了HBx基因及HBx-M13在小鼠肝脏的特异性表达载体。为建立转HBx基因及HBx-M13的小鼠动物模型、进一步研究HBx在肝癌发病过程中的分子生物学机理奠定了基础。 相似文献
2.
Emmanuelle Fontoura José Darival Ferreira Jamile Bubadué Ana Maria Ribeiro Leonardo Kerber 《Journal of morphology》2020,281(10):1223-1240
A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology. 相似文献
3.
This article correlates colonization with parameters, such as chemotaxis, biofilm formation, and bacterial growth, that are
believed to be connected. We show here, by using two varieties of soybean plants that seeds axenically produced exudates,
induced a chemotactic response in Bacillus amyloliquefaciens, whereas root exudates did not, even when the exudates, also collected under axenic conditions, were concentrated up to 200-fold.
Root exudates did not support bacterial cell division, whereas seed exudates contain compounds that support active cell division
and high cell biomass at stationary phase. Seed exudates of the two soybean varieties also induced biofilm formation. B. amyloliquefaciens colonized both seeds and roots, and plant variety significantly affected bacterial root colonization, whereas it did not
affect seed colonization. Colonization of roots in B. amyloliquefaciens occurred despite the lack of chemotaxis and growth stimulation by root exudates. The data presented in this article suggest
that soybean seed colonization, but not root colonization, by B. amyloliquefaciens is influenced by chemotaxis, growth, and biofilm formation and that this may be caused by qualitative changes of the composition
of root exudates. 相似文献
4.
Souto GI Correa OS Montecchia MS Kerber NL Pucheu NL Bachur M García AF 《Journal of applied microbiology》2004,97(6):1247-1256
AIMS: A bacterial strain producing antifungal compounds active against the plant pathogenic fungi Fusarium, Rhizoctonia and Sclerotinia has been characterized and shown to control Rhizoctonia root rot of soya bean. METHODS AND RESULTS: The metabolites excreted by Bacillus BNM 122 remained active after autoclaving, were resistant over a wide pH range and to hydrolytic enzymes. By (1)H-NMR and thin-layer chromatography analyses surfactin and iturin-like compounds were partially identified. Moreover, soya bean seeds bacterization with BNM 122 in a compost-based formulation was as effective controlling Rhizoctonia solani as pentachloronitrobenzene. According to its 16S rDNA sequence BNM 122 was closely related to Bacillus amyloliquefaciens and Bacillus subtilis. PCR analysis of the 16S-23S rRNA intergenic spacer region and repetitive sequence-based PCR (rep-PCR) genomic fingerprinting revealed a close genetic relationship to B. amyloliquefaciens. However, by physiological characterization using API tests, this strain resembled more B. subtilis. CONCLUSIONS: This is the first report describing the co-production of surfactin and iturin-like compounds by a putative strain of B. amyloliquefaciens. The synergistic effect of both lipopetides is a remarkable trait for a candidate biocontrol agent. SIGNIFICANCE AND IMPACT OF THE STUDY: This kind of research has relevance in order to minimize the use of synthetic fungicides and surfactants, contributing to the preservation of the environment. 相似文献
5.
Iustman LJ Pucheu NL Kerber NL Vandekerckhove J Tadros MH Garcia AF 《Current microbiology》2001,42(5):323-329
Cells of Rhv. sulfidophilum were grown under different conditions in the presence of 32P-phosphate and the corresponding H and L membrane fractions obtained and fractionated by SDS-PAGE. Both membranes showed
almost identical polypeptide composition. The bacteriochlorophyll (Bchl) specific content in H was always lower that in L.
As described before, oxygen did not regulate gene expression. Under high light, an almost two- to threefold decrease of the
cellular specific Bchl content was observed. Pulse and chase experiments showed that transitions from aerobiosis to light-anaerobiosis
did not quantitatively affect the Bchl content of the membranes, although a turnover of the 32P-phosphate and 35S-methionine was observed. LHI β was the only polypeptidic subunit of the Bchl-binding polypeptides that was phosphorylated
in vivo, and phosphotyrosine was the only phosphorylated amino acid detectable. The phosphorylated LHI β was determined to
be insoluble in the organic solvent mixture of (vol/vol) 1:1 chloroform-methanol containing ammonium acetate (0.1 m final
concentration). Treatment with a chaotropic agent such as Na2CO3 solubilized the phosphorylated LHI β, indicating that part of this posttranslationally modified polypeptide was not inserted
in a transmembrane position. These results were used to speculate about the regulatory properties of this posttranslational
modification of LHI β on membrane differentiation.
Received: 30 August 2000 / Accepted: 2 October 2000 相似文献
6.
The rodent Neoepiblema acreensis (Chinchilloidea: Neoepiblemidae) is member of a lineage that reached gigantic dimensions during the Late Miocene of South America—the Neoepiblemidae. In this paper, the cranial anatomy of this rodent is reviewed. Noninvasive imaging is used to reveal internal structures. Our review is based mainly on an almost complete cranium from the Upper Miocene deposits of the western Amazonia of Brazil. The cranium has an elongated rostrum, large frontal sinuses, a deep temporal fossa, well-developed sagittal, nuchal, medial occipital, and secondary crests, and a tympanic fenestra connected to the external acoustic meatus by a thin ventral cleft. Remarkably, the cranium shows the presence of fossae on the posterior region of the frontal and parietal bones, and a “W-shaped” fronto-parietal suture, which are not present in other analyzed chinchilloids. This study contributes to the knowledge of the morphology of this extinct rodent as well as to the phylogenetic relationships and paleobiology of neoepiblemids. 相似文献
7.
Alessandro S Guimarães Filipe B Carmo Marcos B Heinemann Ricardo WD Portela Roberto Meyer Andrey P Lage Núbia Seyffert Anderson Miyoshi Vasco Azevedo Aurora MG Gouveia 《BMC veterinary research》2011,7(1):1-5
Background
Multiple congenital ocular anomalies (MCOA) syndrome is a hereditary congenital eye defect that was first described in Silver colored Rocky Mountain horses. The mutation causing this disease is located within a defined chromosomal interval, which also contains the gene and mutation that is associated with the Silver coat color (PMEL17, exon 11). Horses that are homozygous for the disease-causing allele have multiple defects (MCOA-phenotype), whilst the heterozygous horses predominantly have cysts of the iris, ciliary body or retina (Cyst-phenotype). It has been argued that these ocular defects are caused by a recent mutation that is restricted to horses that are related to the Rocky Mountain Horse breed. For that reason we have examined another horse breed, the Icelandic horse, which is historically quite divergent from Rocky Mountain horses.Results
We examined 24 Icelandic horses and established that the MCOA syndrome is present in this breed. Four of these horses were categorised as having the MCOA-phenotype and were genotyped as being homozygous for the PMEL17 mutation. The most common clinical signs included megaloglobus, iris stromal hypoplasia, abnormal pectinate ligaments, iridociliary cysts occasionally extending into the peripheral retina and cataracts. The cysts and pectinate ligament abnormalities were observed in the temporal quadrant of the eyes. Fourteen horses were heterozygous for the PMEL17 mutation and were characterized as having the Cyst-phenotype with cysts and occasionally curvilinear streaks in the peripheral retina. Three additional horses were genotyped as PMEL17 heterozygotes, but in these horses we were unable to detect cysts or other forms of anomalies. One eye of a severely vision-impaired 18 month-old stallion, homozygous for the PMEL17 mutation was examined by light microscopy. Redundant duplication of non-pigmented ciliary body epithelium, sometimes forming cysts bulging into the posterior chamber and localized areas of atrophy in the peripheral retina were seen.Conclusions
The MCOA syndrome is segregating with the PMEL17 mutation in the Icelandic Horse population. This needs to be taken into consideration in breeding decisions and highlights the fact that MCOA syndrome is present in a breed that are more ancient and not closely related to the Rocky Mountain Horse breed. 相似文献8.
The erythrocytes of blood clams (arcidae) are flattened, elliptical, and nucleated. They contain elliptical marginal bands (MBs) of microtubules, each physically associated with a pair of centrioles marginal bands (MBs) of microtubles, each physically associated with a pair of centrioles (Cohen, W., and I. Nemhauser, 1980, J. Cell Biol., 86:286-291). The MBs were found to be cold labile in living cells, disappearing within 1-2 h at 0 degrees C. After the cells had been rewarmed for 1-2 h, continuous MBs with associated centrioles were once again present. Time-course studies utilizing phase contrast, antitubulin immunofluorescence, and electron microscopy of cytoskeletons prepared during rewarming revealed structural evidence of centriole participation in MB reassembly. At the earliest stage of reassembly, a continuous MB was not present. Instead, relatively short and straight microtubules focused on a pointed centriolar “pole,” and none were present elsewhere in the cytoskeleton. Thin continuous MBs then formed, still pointed in the centriolar region. Subsequently, the MBs regained ellipticity, with their thickness gradually increasing but not reaching that of controls even after several hours of rewarming. At these later time points, microtubules still radiated from the centrioles and joined the MBs some distance away. In the presence of 0.1 mM colchicines, MB reassembly was arrested at the pointed stage. Electron microscopic observations indicate that pericentriolar material is involved in microtubule nucleation in this system, rather than the centriolar triplets directly. The results suggest a model in which the centrioles and associated material nucleate assembly and growth of microtubules in diverging directions around the cell periphery. Microtubules of opposite polarity would then pass each other at the end of the cell distal to the centrioles, with continued elongation eventually closing the MB ellipse behind the centriole pair. 相似文献
9.
Martin W. Bratschi Marie-Thérèse Ruf Arianna Andreoli Jacques C. Minyem Sarah Kerber Fidèle G. Wantong James Pritchard Victoria Chakwera Christian Beuret Matthias Wittwer Djeunga Noumen Nadia Schürch Alphonse Um Book Gerd Pluschke 《PLoS neglected tropical diseases》2014,8(3)
Buruli ulcer (BU), a neglected tropical disease of the skin and subcutaneous tissue, is caused by Mycobacterium ulcerans and is the third most common mycobacterial disease after tuberculosis and leprosy. While there is a strong association of the occurrence of the disease with stagnant or slow flowing water bodies, the exact mode of transmission of BU is not clear. M. ulcerans has emerged from the environmental fish pathogen M. marinum by acquisition of a virulence plasmid encoding the enzymes required for the production of the cytotoxic macrolide toxin mycolactone, which is a key factor in the pathogenesis of BU. Comparative genomic studies have further shown extensive pseudogene formation and downsizing of the M. ulcerans genome, indicative for an adaptation to a more stable ecological niche. This has raised the question whether this pathogen is still present in water-associated environmental reservoirs. Here we show persistence of M. ulcerans specific DNA sequences over a period of more than two years at a water contact location of BU patients in an endemic village of Cameroon. At defined positions in a shallow water hole used by the villagers for washing and bathing, detritus remained consistently positive for M. ulcerans DNA. The observed mean real-time PCR Ct difference of 1.45 between the insertion sequences IS2606 and IS2404 indicated that lineage 3 M. ulcerans, which cause human disease, persisted in this environment after successful treatment of all local patients. Underwater decaying organic matter may therefore represent a reservoir of M. ulcerans for direct infection of skin lesions or vector-associated transmission. 相似文献
10.
Brunotte L Kerber R Shang W Hauer F Hass M Gabriel M Lelke M Busch C Stark H Svergun DI Betzel C Perbandt M Günther S 《The Journal of biological chemistry》2011,286(44):38748-38756