全文获取类型
收费全文 | 360篇 |
免费 | 39篇 |
国内免费 | 1篇 |
出版年
2021年 | 6篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 17篇 |
2012年 | 18篇 |
2011年 | 26篇 |
2010年 | 17篇 |
2009年 | 22篇 |
2008年 | 22篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 12篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 16篇 |
1997年 | 10篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
81.
V. Savolainen R. Corbaz C. Moncousin R. Spichiger J.-F. Manen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,90(7-8):1138-1141
The chloroplastic atpB-rbcL spacer and the first 53 codons of the rbcL coding sequence was sequenced for 40 apple cultivars and 15 wild species. This chloroplast DNA region is 904 base pairs long, and only five mutations sites were found among the tested samples. Although the cpDNA variation was low, some parentages are proposed based on the maternal inheritance of plastid DNA: the male and female parents are specified, or else suggested, for Worcester, Discovery, Starking, Starkrimson, Kidd's Orange Red, Priscilla, and Gloster, as well as for the putative wild origin for Malus x domestica. 相似文献
82.
Current phylogenetic tree reconstruction methods assume that there is a
single underlying tree topology for all sites along the sequence. The
presence of mosaic sequences due to recombination violates this assumption
and will cause phylogenetic methods to give misleading results due to the
imposition of a single tree topology on all sites. The detection of mosaic
sequences caused by recombination is therefore an important first step in
phylogenetic analysis. A graphical method for the detection of
recombination, based on the least squares method of phylogenetic
estimation, is presented here. This method locates putative recombination
breakpoints by moving a window along the sequence. The performance of the
method is assessed by simulation and by its application to a real data set.
相似文献
83.
We used the repetitive character of transposable elements to isolate a
non-LTR retrotransposon in Drosophila subobscura. bilbo, as we have called
it, has homology to TRIM and LOA elements. Sequence analysis showed a 5'
untranslated region (UTR), an open reading frame (ORF) with no RNA-binding
domains, a downstream ORF that had structural homology to that of the I
factor, and, finally, a 3' UTR which ended in several 5-nt repeats. The
results of our phylogenetic and structural analyses shed light on the
evolution of Drosophila non-LTR retrotransposons and support the hypothesis
that an ancestor of these elements was structurally complex.
相似文献
84.
Variation of physico-chemical parameters along a river transect through the Okavango Delta,Botswana 总被引:1,自引:0,他引:1
The Okavango Delta depends on water quantity and quality to sustain its ecosystem services. Whereas many studies have been carried out on its hydrology, few have been done on water quality in the delta. Water pH, electrical conductivity (EC), dissolved oxygen (DO), turbidity, total suspended solids (TSS) and dissolved organic carbon (DOC) were monitored at 10 sites along the Okavango–Boro–Thamalakane–Lake Ngami system almost fortnightly from June 2008 to June 2010. Water quality in the delta was generally good, despite high evapotranspiration rates which would normally produce very saline waters. Electrical conductivity and water temperature increased with distance from Mohembo to Lake Ngami, the former most likely due to evapoconcentration. In contrast, pH, DO, turbidity and TSS decreased with distance from Mohembo to Boro at the lower end of the seasonal floodplain, before increasing again to Lake Ngami. Dissolved oxygen and TSS most likely declined due to biological uptake and particle sedimentation, respectively. Strong and significant relationships were observed between TSS and turbidity and between DOC and EC, indicating that turbidity and EC could be useful proxies for routine estimations of TSS and DOC, respectively, in the delta. 相似文献
85.
The suitability of using macroinvertebrates as bioindicators of stream water quality was tested in the Mkondoa River in an agricultural area at Kilosa, using the rapid bioassessment protocol. The family biotic index (FBI) showed marked variation in water quality along the stream from values ranging from 4.1 to 5.0 in the upstream reaches, indicating good water quality, 5.3 to 5.5 in the mid-reaches and 6.0 to 6.5 in the lower reaches. The water quality index (WQI) indicated that water quality was fair (77 ± 0.98) in the upstream reach of the Mkondoa, marginal (55 ± 0.86) in the midstream reach and poor (33 ± 0.45) in the downstream reach. There were significant relationships between biological oxygen demand and dissolved oxygen and the occurrence of specific taxa, mainly Chironomus and Caenis. Significant changes in macroinvertebrate abundance were mostly related to changes in water quality. As in other parts of the world, macroinvertebrate communities proved to be good biological indicators of water quality and they should be used as bioindicators in long-term monitoring of this river. 相似文献
86.
Protein synthesis, measured as the incorporation of [14C]valine into cell proteins and into proteins secreted into the medium, and albumin production were studied in isolated rat liver hepatocytes. Protein synthesis was substantially higher in cells from fed rats than in cells from fasted rats. Addition of carbohydrates or amino acids increased protein synthesis in cells from fasted rats, whereas no effect was seen in cells from fed rats. Addition of oleate had no effect on protein synthesis. Ethanol inhibited protein synthesis in cells from fasted rats, whereas no or only small effect was seen in cells from fed rats. Simultaneous addition of carbohydrates diminished the inhibitory effect of ethanol, whereas addition of oleate increased the inhibitory effect of ethanol. It is suggested that the rate of protein synthesis in cells from fasted rats could be restricted by lack of precursors for synthesis of nonessential amino acids. The effect of ethanol is explained by an inhibition of gluconeogenesis. 相似文献
87.
88.
89.
Maija-Riitta Hirvonen Hannu Komulainen Leo Paljärvi Kai Savolainen 《Neurochemical research》1989,14(2):143-147
The potential of a single dose of malaoxon (26.2 or 39.2 mg/kg i.p.) to produce convulsions and to increase cerebral levels of inositol-1-phosphate (Ins1P), an intermediate in phosphoinositide (PI) cycle, was followed for 1, 4, or 72 hr. The lower dose of malaoxon did not produce convulsions whereas the higher dose induced convulsions in 60% of the exposed rats. Malaoxon caused a dosedependent, at most 2-fold, increase in brain regional Ins1P levels in nonconvulsing rats as compared to controls. At the higher dose of malaoxon, in convulsing rats, the Ins1P-levels increased 4-fold above the control Ins1P-levels. In nonconvulsing rats, the Ins1P-levels reached their maximum 1–4 hr after the administration of malaoxon, whereas in convulsing rats the levels increased for 72 hr. The results suggest that PI-signalling is associated with convulsions produced by malaoxon. 相似文献
90.
H. Kuittinen M. J. Sillanpää O. Savolainen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(4):573-583
We have mapped QTLs (quantitative trait loci) for an adaptive trait, flowering time, in a selfing annual, Arabidopsis thaliana. To obtain a mapping population we made a cross between an early-summer, annual strain, Li-5, and an individual from a late
over-wintering natural population, Naantali. From the backcross to Li-5 298 progeny were grown, of which 93 of the most extreme
individuals were genotyped. The data were analysed with both interval mapping and composite interval mapping methods to reveal
one major and six minor QTLs, with at least one QTL on each of the five chromosomes. The QTL on chromosome 4 was a major one
with an effect of 17.3 days on flowering time and explaining 53.4% of the total variance. The others had effects of at most
6.5 days, and they accounted for only small portions of the variance. Epistasis was indicated between one pair of the QTLs.
The result of finding one major QTL and little epistasis agrees with previous studies on flowering time in Arabidopsis thaliana and other species. That several QTLs were found was expected considering the large number of possible candidate loci. In
the light of the suggested genetic models of gene action at the candidate loci, epistasis was to be expected. The data showed
that major QTLs for adaptive traits can be detected in non-domesticated species.
Received: 15 January 1997/Accepted: 21 February 1997 相似文献