全文获取类型
收费全文 | 121篇 |
免费 | 8篇 |
专业分类
129篇 |
出版年
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 8篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 2篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1969年 | 1篇 |
1959年 | 1篇 |
1958年 | 5篇 |
1957年 | 2篇 |
1956年 | 4篇 |
1955年 | 5篇 |
1954年 | 4篇 |
1953年 | 7篇 |
1952年 | 1篇 |
1951年 | 4篇 |
1950年 | 3篇 |
1949年 | 3篇 |
1946年 | 1篇 |
1943年 | 1篇 |
1881年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 0 毫秒
1.
Fungi were isolated from soybean plants in ten fields in south-west France. Correspondence analysis (COA) was used to find associations among taxa (species, genera, groups) and sampling units (i.e. one field at one sampling date). The first axis of the COA demonstrated a dominant sampling date effect; the second indicated an association among certain sampling units and specific taxa. Regression analysis of COA coordinate values indicated that fields with high relative isolation frequencies of Fusarium spp., F. oxysporum and ‘other species’ (mostly Chaetomium spp. and sterile fungi) were characterised by greater plant fresh weight and nodule number and lower ratings for root necrosis. Cylindrocarpon spp., Cephalosporium spp. and F. solanihad high relative isolation frequencies in fields with lower plant weight, lower nodule number and higher root necrosis ratings. The relative importance of fungal taxa was also related to soil type. 相似文献
2.
3.
4.
C García-Vielma MI Dávila-Rodríguez F Hernández-Garza RM Cerda-Flores 《Biotechnic & histochemistry》2016,91(2):102-107
We performed a hospital-based, unmatched case-control study to investigate the association between progressive stages of cervical neoplasia and digital analysis of cell proliferation by silver stained nucleolus organizer region associated proteins (AgNORs). We measured cell proliferation levels in the cervical epithelial cells of 10 women with low grade squamous intraepithelial lesions (LG-SIL), eight with high grade squamous intraepithelial lesions (HG-SIL), 11 with cervical cancer (CC) and eight with no cervical lesions (controls) using the AgNORs technique. Cell proliferation was measured by digital image analysis (DIA). DIA revealed increased total areas of AgNORs in HG-SIL and CC compared to LG-SIL and control patients. AgNORs with a kidney or cluster shape exhibited greater areas than those with a spherical or long shape. We propose a cut-off of 118 pixels to differentiate benign (control and LG-SIL) from malignant (HG-SIL and CC) lesions. DIA of AgNORs is a simple and inexpensive method for studying proliferation. The increased total area of AgNORs in malignant lesions provides information regarding cell behavior and may be related to cervical carcinogenesis; however, further validation studies are required to establish its usefulness in cytological analysis. 相似文献
5.
1-Thio-beta-D-galactofuranosides: synthesis and evaluation as beta-D- galactofuranosidase inhibitors
Marino C; Marino K; Miletti L; Manso Alves MJ; Colli W; de Lederkremer RM 《Glycobiology》1998,8(9):901-904
Beta-D-galactofuranosidase is a good chemotherapeutic target for the design
of inhibitors, since beta-D-galactofuranose is a constituent of important
parasite glycoconjugates but is not present in the host mammals. With this
aim, we have synthesized for the first time alkyl, benzyl and aryl
1-thio-beta-D-galactofuranosides by condensation of
penta-O-benzoyl-alpha,beta-D-galactofuranose with the corresponding thiols,
in the presence of SnCl4as catalyst. The complete chemical and
spectroscopical characterization of these compounds showed that the
reaction was stereoselective. Debenzoylation with sodium methoxide afforded
the beta-S-galactofuranosides in high yield. The thioglycosides were tested
as inhibitors of the beta-D- galactofuranosidase of Penicillium fellutanum,
using for the first time 4-nitrophenyl-beta-D-galactofuranoside as
chromogenic substrate. The 4- aminophenyl-1-thio-beta-D-galactofuranoside,
obtained by catalytic hydrogenation of the nitrophenyl derivative, was the
best inhibitor being then an adequate ligand for the preparation of an
affinity phase aimed at the isolation of beta-d-galactofuranosidases from
different sources. Also the inhibitory activity of d-galactono-1, 4-lactone
was shown.
相似文献
6.
7.
We studied the relationship between contaminant concentrations in livers, endohelminth prevalence and physiological indices of chronic stress (spleen size, heterophil/lymphocyte ratios) in Northern Fulmars Fulmarus glacialis collected during the breeding season in Nunavut, Canada. No blood parasites were found, similar to reports for other petrel species elsewhere. However, 54% of Fulmars had gastrointestinal helminths, principally cestodes (52% prevalence, mean intensity of 11 worms), nematodes (34% prevalence, 3.6 worms) and acanthocephalans (3%, eight worms). Both prevalence and intensity of helminth infections were lower for Arctic Fulmars than for Fulmars and other petrels found in southern parts of the species' range. Spleen size was not significantly related to either contaminant concentration or presence of parasites, suggesting that Fulmar health was generally unaffected by contaminant and parasite levels at the colony. However, we cannot rule out the possibility that Fulmars with higher parasitaemias or contaminant loads were in poorer condition and did not attend the breeding colony. 相似文献
8.
Rebecca Vicente-Steijn Roderick W. C. Scherptong Boudewijn P. T. Kruithof Sjoerd N. Duim Marie Jose T. H. Goumans Lambertus J. Wisse Bin Zhou William T. Pu Robert E. Poelmann Martin J. Schalij Michelle D. Tallquist Adriana C. Gittenberger-de Groot Monique RM Jongbloed 《PloS one》2015,10(9)
Background
Morphological and functional differences of the right and left ventricle are apparent in the adult human heart. A differential contribution of cardiac fibroblasts and smooth muscle cells (populations of epicardium-derived cells) to each ventricle may account for part of the morphological-functional disparity. Here we studied the relation between epicardial derivatives and the development of compact ventricular myocardium.Results
Wildtype and Wt1CreERT2/+ reporter mice were used to study WT-1 expressing cells, and Tcf21lacZ/+ reporter mice and PDGFRα-/-;Tcf21LacZ/+ mice to study the formation of the cardiac fibroblast population. After covering the heart, intramyocardial WT-1+ cells were first observed at the inner curvature, the right ventricular postero-lateral wall and left ventricular apical wall. Later, WT-1+ cells were present in the walls of both ventricles, but significantly more pronounced in the left ventricle. Tcf21-LacZ + cells followed the same distribution pattern as WT-1+ cells but at later stages, indicating a timing difference between these cell populations. Within the right ventricle, WT-1+ and Tcf21-lacZ+ cell distribution was more pronounced in the posterior inlet part. A gradual increase in myocardial wall thickness was observed early in the left ventricle and at later stages in the right ventricle. PDGFRα-/-;Tcf21LacZ/+ mice showed deficient epicardium, diminished number of Tcf21-LacZ + cells and reduced ventricular compaction.Conclusions
During normal heart development, spatio-temporal differences in contribution of WT-1 and Tcf21-LacZ + cells to right versus left ventricular myocardium occur parallel to myocardial thickening. These findings may relate to lateralized differences in ventricular (patho)morphology in humans. 相似文献9.
Background
Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development. 相似文献10.
SAMUEL K. SHEPPARD FRANCES M. COLLES NOEL D.
McCARTHY NORVAL J. C. STRACHAN IAIN D. OGDEN KEN J. FORBES JOHN F. DALLAS MARTIN C. J. MAIDEN 《Molecular ecology》2011,20(16):3484-3490
Bacterial populations can display high levels of genetic structuring but the forces that influence this are incompletely understood. Here, by combining modelling approaches with multilocus sequence data for the zoonotic pathogen Campylobacter, we investigated how ecological factors such as niche (host) separation relate to population structure. We analysed seven housekeeping genes from published C. jejuni and C. coli isolate collections from a range of food and wild animal sources as well as abiotic environments. By reconstructing genetic structure and the patterns of ancestry, we quantified C. jejuni host association, inferred ancestral populations, investigated genetic admixture in different hosts and determined the host origin of recombinant C. jejuni alleles found in hybrid C. coli lineages. Phylogenetically distinct C. jejuni lineages were associated with phylogenetically distinct wild birds. However, in the farm environment, phylogenetically distant host animals shared several C. jejuni lineages that could not be segregated according to host origin using these analyses. Furthermore, of the introgressed C. jejuni alleles found in C. coli lineages, 73% were attributed to genotypes associated with food animals. Our results are consistent with an evolutionary scenario where distinct Campylobacter lineages are associated with different host species but the ecological factors that maintain this are different in domestic animals such that phylogenetically distant animals can harbour closely related strains. 相似文献