全文获取类型
收费全文 | 160篇 |
免费 | 11篇 |
出版年
2020年 | 2篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 4篇 |
2012年 | 10篇 |
2011年 | 12篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 5篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1949年 | 2篇 |
1948年 | 2篇 |
1946年 | 2篇 |
1942年 | 2篇 |
1941年 | 3篇 |
1940年 | 3篇 |
1938年 | 2篇 |
1933年 | 2篇 |
1927年 | 3篇 |
1924年 | 2篇 |
1923年 | 2篇 |
1922年 | 3篇 |
1917年 | 1篇 |
1913年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 15 毫秒
1.
Gillian D Alton David L Pearl Ken G Bateman W Bruce McNab Olaf Berke 《BMC veterinary research》2010,6(1):42
Background
Ontario provincial abattoirs have the potential to be important sources of syndromic surveillance data for emerging diseases of concern to animal health, public health and food safety. The objectives of this study were to: (1) describe provincially inspected abattoirs processing cattle in Ontario in terms of the number of abattoirs, the number of weeks abattoirs process cattle, geographical distribution, types of whole carcass condemnations reported, and the distance animals are shipped for slaughter; and (2) identify various seasonal, secular, disease and non-disease factors that might bias the results of quantitative methods, such as cluster detection methods, used for food animal syndromic surveillance. 相似文献2.
3.
Home ranges and habitat use are described for three adult female, one adult male, and one subadult male wolverines in the Kluane Game Sanctuary, Yukon. When long distance excursions are not included, home ranges of wolverines in the Kluane Game Sanctuary were between 76 and 269 km2 for females and 209 and 269 km2 for males. Habitat use of females was similar to habitat availability. Males used subalpine coniferous habitats more frequently than other habitat types during winter. Although individual variation in the use of forest cover types, aspects, slopes and elevations was apparent, seasonal use did not differ from availability for each sex. Within the 1590 km2 study area, three adult males and six adult females were present, corresponding to a density of one resident wolverine 177 km-2 . 相似文献
4.
Cytogenetic Definition and Morphogenetic Analysis of Delta, a Gene Affecting Neurogenesis in Drosophila Melanogaster 总被引:4,自引:3,他引:1
下载免费PDF全文
![点击此处可从《Genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have conducted a genetic analysis of a small interval of the third chromosome known to include Delta (Dl), a locus that affects the segregation of the ectoderm into neural and epidermal lineages during embryogenesis and the morphogenesis of some ectodermally derived structures, in Drosophila melanogaster. This analysis has led to the definition of seven independent complementation groups, one of which is Delta, within the interval extending from 91F6-13 to 92A2. Among the extant mutations in these seven loci, only mutations in Dl lead to the so-called neurogenic phenotype: hypertrophy of the nervous system and reduction of the epidermis. Combined cytogenetic and genetic analyses allow us to define absolute proximal (91F5-92A1) and distal (92A2) cytogenetic limits for the Dl locus. We have isolated hypomorphic and amorphic alleles of Dl and find that, for any given allele, there is an inverse correlation between neural hypertrophy and epidermal reduction in embryos and a direct correlation between the severity of embryonic phenotypes in mutant homozygotes and hemizygotes and the imaginal phenotype in heterozygous adults. 相似文献
5.
Incidence of Infectious Drug Resistance Among Fecal Coliforms Isolated from Raw Sewage 总被引:7,自引:6,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Raw sewage was examined for the incidence of antibiotic-resistant coliforms present among both total and fecal coliforms. In both groups, it was found that approximately 3% of the coliform bacteria were resistant to two or more antibiotics. Of these organisms, 48% were capable of transferring all or part of their antibiotic resistance to an antibiotic-sensitive, F−, derivative of Escherichia coli K-12. Among the R factors identified, those conferring resistance to streptomycin-tetracycline, ampicillin-streptomycin-tetracycline, and ampicillin or ampicillin-streptomycin accounted for 23, 20, and 15%, respectively, of the total R factors detected. The data indicate a significant level of infectious drug resistance among the fecal coliforms of the urban population. The data indicate further that because of the high incidence of coliform bacteria found to be doubly resistant to streptomycin and tetracyline, the inclusion of these antibiotics in selective media used for routine total or fecal coliform counts may serve to identify domestic sources of pollution. 相似文献
6.
Incidence of Infectious Drug Resistance Among Lactose-Fermenting Bacteria Isolated from Raw and Treated Sewage 总被引:14,自引:11,他引:3
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Raw and treated sewage samples were examined for antibiotic-resistant, lactose-fermenting bacteria. Approximately 1% of the total lactose-fermenting bacteria were multiply resistant. Of these organisms, 50% were capable of transferring all or part of their resistance to a drug-sensitive recipient. Only 43% of those isolated on media containing a single antibiotic were capable of resistance transfer, whereas 57% of those recovered on multiple antibiotic plates transferred resistance. R factors conferring resistance to chloramphenicol, streptomycin, and tetracycline; streptomycin and tetracycline; and ampicillin, streptomycin, and tetracycline accounted for 22, 19, and 15%, respectively, of those identified. The data indicate a significant level of infectious drug resistance among the intestinal bacteria of the urban population. 相似文献
7.
W. Austin Spruill Alton L. Steiner Laura L. Tres A. L. Kierszenbaum 《Molecular and cellular biochemistry》1984,60(2):147-157
Summary Protein-bound cyclic AMP (cAMP) levels in cultured rat Sertoli cells have been determined after exposure to follicle-stimulating hormone (FSH) and agents which elevate intracellular cAMP or mimic cAMP action. Changes in the content of protein-bound cAMP were correlated with changes in receptor availability determined by measuring [3H] cAMP binding. Using the photoaffinity analog of cAMP, 8-N3 [32P] cAMP, two major cAMP-binding proteins in Sertoli cell cytosol, with molecular weights of 47 000 and 53 000 daltons, were identified as regulatory subunits of type I and type II cAMP-dependent protein kinases, respectively. Densitometric analysis of autoradiograms demonstrated differential activation of the two isozymes in response to treatment with FSH and other agents. Results of this study demonstrate the value of measuring changes in protein-bound cAMP and the utility of the photoaffinity labeling technique in correlating hormone-dependent processes in which activation of cAMP-dependent protein kinase occurs. 相似文献
8.
Anil G. Palekar Suresh S. Tate Alton Meister 《Biochemical and biophysical research communications》1975,62(3):651-657
After rats were injected with the convulsant methionine sulfoximine, there was a rapid decrease in the glutathione concentrations of the kidney and liver, but there was no measurable effect (within 5 hours) on brain glutathione. The maximum decreases in the glutathione concentrations of kidney and liver were observed 1 hr after injection and were about 60 and 40%, respectively, of the control levels. The findings suggest that there may be at least two pools of tissue glutathione. Studies in which other amino acids were injected, and earlier studies, are consistent with the conclusion that methionine sulfoximine affects glutathione synthesis by inhibiting γ-glutamylcysteine synthetase. Injection of glycylglycine also decreased glutathione levels, an effect probably mediated by γ-glutamyltranspeptidase. 相似文献
9.
Zhong R Hernandez A Alton KB Kishnani NS Patrick JE 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2002,772(1):191-195
A rapid HPLC method was developed for quantification of unbound evernimicin in human plasma. Protein-free samples prepared by ultrafiltration were injected directly onto a polymeric reversed-phase column and the eluent monitored at 302 nm. Evernimicin that eluted within 3.5 min was well resolved from endogenous components. Linearity was established between peak height and evernimicin concentration from 25 to 2500 ng/ml. Assay precision (C.V.) was within 5% while bias was no greater than 3%. This method has been used for the ex vivo assessment of evernimicin protein binding in human plasma from safety and tolerance as well as liver dysfunction and renal insufficiency studies. 相似文献
10.
Kagawa HK Yaoi T Brocchieri L McMillan RA Alton T Trent JD 《Molecular microbiology》2003,49(1):143-156
The hyperthermoacidophilic archaeon Sulfolobus shibatae contains group II chaperonins, known as rosettasomes, which are two nine-membered rings composed of three different 60 kDa subunits (TF55 alpha, beta and gamma). We sequenced the gene for the gamma subunit and studied the temperature-dependent changes in alpha, beta and gamma expression, their association into rosettasomes and their phylogenetic relationships. Alpha and beta gene expression was increased by heat shock (30 min, 86 degrees C) and decreased by cold shock (30 min, 60 degrees C). Gamma expression was undetectable at heat shock temperatures and low at normal temperatures (75-79 degrees C), but induced by cold shock. Polyacrylamide gel electrophoresis indicated that in vitro alpha and beta subunits form homo-oligomeric rosettasomes, and mixtures of alpha, beta and gamma form hetero-oligomeric rosettasomes. Transmission electron microscopy revealed that beta homo-oligomeric rosettasomes and all hetero-oligomeric rosettasomes associate into filaments. In vivo rosettasomes were hetero-oligomeric with an average subunit ratio of 1alpha:1beta:0.1gamma in cultures grown at 75 degrees C, a ratio of 1alpha:3beta:1gamma in cultures grown at 60 degrees C and a ratio of 2alpha:3beta:0gamma after 86 degrees C heat shock. Using differential scanning calorimetry, we determined denaturation temperatures (Tm) for alpha, beta and gamma subunits of 95.7 degrees C, 96.7 degrees C and 80.5 degrees C, respectively, and observed that rosettasomes containing gamma were relatively less stable than those with alpha and/or beta only. We propose that, in vivo, the rosettasome structure is determined by the relative abundance of subunits and not by a fixed geometry. Furthermore, phylogenetic analyses indicate that archaeal chaperonin subunits underwent multiple duplication events within species (paralogy). The independent evolution of these paralogues raises the possibility that chaperonins have functionally diversified between species. 相似文献