全文获取类型
收费全文 | 174篇 |
免费 | 18篇 |
国内免费 | 1篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 8篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 2篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1971年 | 3篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有193条查询结果,搜索用时 31 毫秒
71.
HPLC-MS-based methods for the study of metabonomics 总被引:25,自引:0,他引:25
Wilson ID Plumb R Granger J Major H Williams R Lenz EM 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,817(1):67-76
The development and use of HPLC-MS for the study of metabonomics is reviewed. To date the technique has been applied to the analysis of urine samples obtained from studies in rodents in investigations of physiological variation (e.g., factors such as strain, gender, diurnal variation, etc.) and toxicity. Examples are provided of the use of conventional HPLC, capillary methods and the recently introduced high-resolution systems based on a combination of high pressure and small particle size ("UPLC"). Comparison is also made of the use of 1H NMR spectroscopy and HPLC-MS for the analysis of biofluid samples and the advantages and limitations of the two approaches are assessed. Likely future developments are considered. 相似文献
72.
Rhopalosiphum padi and Sitobion avenae alates were collected from colonised winter cereals and maize in N.E. Spain and fed on young wheat plants for 7–10 days in the glasshouse. Then, aphids were killed and the plants on which aphids reproduced were kept in the glasshouse for 30–40 days. ELISA of infested plants was made using polyclonal and monoclonal antisera against PAV-, RPV- and MAV-like isolates. In autumn and spring, MAV serotypes were transmitted by S. avenae and R. padi , mainly in mixed infections with PAV serotypes. This possibly explains the high frequency of MAV-like isolates and their previously recorded year-to-year stability in maize, grain and forage winter cereals and cereal volunteers. PAV-like isolates were rarely transmitted by S. avenae and its spread thus depends almost exclusively on R. padi. These results confirm the importance of forage cereals and cereal volunteers as virus sources for winter cereal infection in the autumn, and the latter as a source of BYDV for maize in spring. 相似文献
73.
74.
Structure and regulation of the anthranilate synthase genes in Pseudomonas aeruginosa: II. Cloning and expression in Escherichia coli 总被引:7,自引:0,他引:7
Crawford IP; Wilde A; Yelverton EM; Figurski D; Hedges RW 《Molecular biology and evolution》1986,3(5):449-458
The genes for the large and small subunits of anthranilate synthase (trpE
and trpG, respectively) have been cloned from Pseudomonas aeruginosa PAC174
into E. coli by R-prime formation with the broad-host- range plasmid
R68.44. Sequential subcloning into plasmid vectors reduced the active
Pseudomonas DNA fragment to a length of 3.1 kb. We obtained evidence that
this region contains the promoter for its own expression and retains a
vestigial regulatory response to tryptophan scarcity or excess.
相似文献
75.
RW Dapson 《Biotechnic & histochemistry》2016,91(8):522-531
During the 1860’s, Hugo Schiff studied many reactions between amines and aldehydes, some of which have been used in histochemistry, at times without credit to Schiff. Much controversy has surrounded the chemical structures and reaction mechanisms of the compounds involved, but modern analytical techniques have clarified the picture. I review these reactions here. I used molecular modeling software to investigate dyes that contain primary amines representing eight chemical families. All dyes were known to perform satisfactorily for detecting aldehydes in tissue sections. The models verified the correct chemical structures at various points in their reactions and also determined how decolorization occurred in those with “leuco” forms. Decolorization in the presence of sulfurous acid can occur by either adduction or reduction depending on the dye. The final condensation product with aldehyde was determined to be either a C-sulfonic acid adduct on the carbonyl carbon atom or an aminal at the same atom. Based on the various outcomes, I have placed the dyes and their reactions into five categories. Because Hugo Schiff studied the reactions between aldehydes and amines with and without various acids or alcohol, it is only proper to call each of them Schiff reactions that used various types of Schiff reagents. 相似文献
76.
77.
Paul J. Blanchfield Lori S. Tate John M. Plumb Marie-Laure Acolas Ken G. Beaty 《Aquatic Ecology》2009,43(3):777-787
The need for cold, well-oxygenated waters significantly reduces the habitat available for lake trout (Salvelinus namaycush) during stratification of small temperate lakes. We examined the spatial and pelagic distribution of lake trout over two
consecutive summers and winters and tested whether winter increased habitat availability and access to littoral regions in
a boreal shield lake in which pelagic prey fish are absent. In winter, lake trout had a narrowly defined pelagic distribution
that was skewed to the upper 3 m of the water column and spatially situated in the central region of the lake. Individual
core areas of use (50% Kernel utilization distributions) in winter were much reduced (75%) and spatially non-overlapping compared
to summer areas, but activity levels were similar between seasons. Winter habitat selection is in contrast to observations
from the stratified season, when lake trout were consistently located in much deeper waters (>6 m) and widely distributed
throughout the lake. Winter distribution of lake trout appeared to be strongly influenced by ambient light levels; snow depth
and day length accounted for up to 69% of the variation in daily median fish depth. More restricted habitat use during winter
than summer was in contrast to our original prediction and illustrates that a different suite of factors influence lake trout
distribution between these seasons. 相似文献
78.
Kaksonen AH Plumb JJ Robertson WJ Spring S Schumann P Franzmann PD Puhakka JA 《Applied and environmental microbiology》2006,72(5):3759-3762
Thermophilic sulfate-reducing bacteria were enriched from samples obtained from a geothermal underground mine in Japan. The enrichment cultures contained bacteria affiliated with the genera Desulfotomaculum, Thermanaeromonas, Thermincola, Thermovenabulum, Moorella, "Natronoanaerobium," and Clostridium. Two novel thermophilic sulfate-reducing strains, RL50JIII and RL80JIV, affiliated with the genera Desulfotomaculum and Thermanaeromonas, respectively, were isolated. 相似文献
79.
Hawkes RB Franzmann PD O'Hara G Plumb JJ 《Extremophiles : life under extreme conditions》2006,10(6):525-530
A new species of Archaea was isolated from an industrial mineral sulphide bioleach heap. Strain BH2, a non-motile pleomorphic coccus, was capable of chemomixotrophic growth on ferrous sulphate and yeast extract. Growth was not supported in the absence of yeast extract. Phylogenetic analysis based on the 16S rRNA gene showed that strain BH2 was most closely related to the species Ferroplasma acidiphilum; however, it showed only 95% sequence similarity with this species. Strain BH2 had a temperature optimum of 53.6°C and a temperature range for growth between 22 and 63°C. Thus, it is the first moderately thermophilic member of the genus Ferroplasma. The optimum pH for the growth of the strain occurred between pH 1.0 and 1.2 and the lowest pH at which growth was observed was 0.4. Based on 16S rRNA gene sequence analysis and other physiological characteristics, strain BH2 constitutes a new species within the genus Ferroplasma. The name Ferroplasma cupricumulans is proposed for the new species and strain BH2 (DSM 16651) is proposed as the type strain. 相似文献
80.
The principal habitat of polar bears Ursus maritimus is sea ice where they hunt seals. Much of the sea ice habitat is scattered or with leads of open water. Adults are good swimmers.
They are well adapted to cold water, while small cubs do not yet have fat layer sufficient to avoid chilling if swimming in
icy water for any prolonged period of time. An important question is thus how female mothers and their cubs may behave to
avoid that cubs get chilled, but at the same time making it possible for the families to hunt is those areas. We describe
an observation of a polar bear cub on its mother’s back while the mother was swimming among ice floes in Svalbard, Norwegian
Arctic. Similar observations are to our knowledge not earlier described in the scientific literature. We point out that this
behaviour minimize exposure to cold water and hence significantly may reduce chilling of the cub. It may also be a way for
the mother to transfer cubs not yet able or willing to swim. The behaviour may be necessary to allow the families to get around
in areas of sea ice with many open leads. 相似文献