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91.
Paracoccus denitrificans was grown on either unlabelled glucose, [1-13C]glucose or [6-13C]glucose as the sole carbon source for growth. The cells were then incubated with a range of 14C-glucose substrates to compare the 14CO2-evolution rates between cells grown on the glucose and the 13C-labelled glucose. Cells grown on 13C-glucose had significantly faster rates of 14CO2-evolution than those grown on unlabelled glucose. The % yields of 14CO2, per [1-14C]-, [6-14C]- and [U-14C]glucose supplied were also substantially greater than those measured for cells grown on unlabelled glucose. The data indicated that growth of Paracoccus on 13C-enriched glucose substrates resulted in cells with notably different 14C-glucose oxidation metabolism compared to that observed in cells grown on unlabelled glucose. 相似文献
92.
Some factors affecting the production, by cultured baby-hamster kidney cells, of BHK glycoprotein I which cross-reacts immunologically with Tamm-Horsfall glycoprotein.
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F J Bloomfield D R Dunstan C L Foster F Serafini-Cessi R D Marshall 《The Biochemical journal》1977,164(1):41-51
Cultured baby-hamster kidney cells (BHK-21/C13), which are adapted to grow in suspension (strain 2P), roduce a glycoprotein, termed BHK glycoprotein I, which cross-reacts immunologically with hamster urinary (Tamm-Horsfall glycoprotein. BHK glycoprotein I was isolated in an electrophoretically (sodium dodecyl sulphate/polyacrylamide gel) homogeneous form by application of affinity chromatography to the medium in which cells had been cultured. Insolubilized anti-(Tamm-Horsfall glycoprotein immunoglobulin G) was used as the adsorbent. The amount of BHK glycoprotein I associated with the cultured cells was found by both radioimmunoassay and immunofluorescence to be related to the amount of Ca2+ in the medium and to the particular stage of the cell cycle. 5'-Nucleotidase was also shed by the cells into the culture medium in amounts related to the stage of the cell cycle. The turnover of hamster Tamm-Horsfall glycoprotein in vivo appeared to be considerably more rapid than can be accounted for by cell turnover. Hamster Tamm-Horsfall glycoprotein was shown to be ineffective in inhibiting agglutination of chicken erythrocytes caused by influenza virus. 相似文献
93.
Credille KM Guyon R André C Murphy K Tucker K Barnhart KF Dunstan RW 《Cytogenetic and genome research》2005,108(4):328-332
In order to extend knowledge of the process of cornification across species and to be better able to recognize inborn errors in keratin synthesis in the dog, we describe the organization and chromosome mapping of canine KRT1 and KRT2E and compare these results to human and murine sequence data. The coding regions of KRT1 and KRT2E are 1,860 bp and 1,902 bp respectively, distributed over nine exons. Both genes are localized on the canine radiation hybrid map to chromosome 27 in the type II keratin gene cluster close to polymorphic markers. These genes are highly conserved across species and based on both genomic and amino acid sequences, canine KRT1 and KRT2E share greater homology with humans than with mice. 相似文献
94.
Theoleyre S Wittrant Y Couillaud S Vusio P Berreur M Dunstan C Blanchard F Rédini F Heymann D 《Biochimica et biophysica acta》2004,1644(1):1-7
Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), an inducer of osteoclastogenesis via its receptor RANK. We recently demonstrated that OPG also exerts a direct effect in osteoclasts by regulating protease expression. Herein, we showed that OPG-induced pro-matrix metalloproteinase-9 activity was abolished by ras/MAPK inhibitors in purified osteoclasts. OPG induced the phosphorylation of p38 and ERK1/2 in RAW264.7 cells. Only p38 activation was totally abolished by a blocking anti-RANKL antibody or an excess of RANKL. Surface plasmon resonance experiments revealed that RANK, RANKL and OPG are able to form a tertiary complex. These results suggested a potential formation of a tertiary complex RANK-RANKL-OPG on osteoclasts. Thus, OPG is not only a soluble decoy receptor for RANKL but must be also considered as a direct effector of osteoclast functions. 相似文献
95.
Two successive randomized trials examined the effect of an increased intake of fatty fish, or the use of fish oil supplements,
in reducing mortality in men with heart disease. The Diet and Reinfarction Trial (DART) was conducted in 2033 men who were
recovering from acute myocardial infarction (MI). Those who were advised to eat fatty fish (or who opted to take fish oil
capsules instead) had a 29% reduction in all-cause mortality over the following two years compared with those not so advised.
The effect appeared in the first few months of the trial. The Diet and Angina Randomized Trial (DART 2) involved 3114 men
with stable angina. Advice to eat fatty fish did not reduce mortality, and taking fish oil capsules was associated with a
higher risk of cardiac and sudden death. The adverse effects of fish or fish oil were restricted to men not taking β-blockers
or dihydropyridine calcium-channel blockers, and were greater in those taking digoxin. Evidence from other sources strongly
suggests an anti-arrhythmic action of fish oil, particularly after MI or in the presence of acute ischemia. The apparently
conflicting results of the two trials may reflect different actions of n-3 fatty acids in acute and chronic conditions, together
with different effects of eating fish and taking fish oil capsules. A mechanism is proposed that could account for these findings. 相似文献
96.
Erythromycin production dynamics in stirred, baffled shaken and non-baffled shaken flasks was strongly correlated with the different distributions of hyphal particle diameters observed. Production only took place when hyphal fragments with diameters greater than 88 m were observed. Results are consistent with significant hyphal breakage rates, even in non-baffled shaken flasks. 相似文献
97.
Jin-Zhuo Dong Gilles Pilate Suzanne R. A brams David I. Dunstan 《Physiologia plantarum》1994,90(3):513-521
In white spruce ( Picea glauca ) protoplasts, abscisic acid (ABA) and optically pure ABA analogs induced expression of a reporter gene under regulation of a wheat ABA-responsive promoter. A fusion of a 650 bp promoter fragment from the wheat Em gene promoter and the Escherichia coli uidA sequence encoding β -glucuronidase (GUS) was linked in the plasmid pBM 113Kp. Expression of the Em-uidA fusion varied among 6 white spruce genotypes. Protoplasts from 4-day-old embryogenic suspension cultures gave the highest GUS activity relative 10 other stages in the 7-day growth cycle of suspension cultures. Racemic ABA [R.S-(±)-ABA] induced a significant increase of protoplast GUS activity over background at a concentration of 1 × 10−5 M , but maximum GUS activity was found at 1 × 10−3 M , ABA stereochemistry had a significant effect on gene expression. The natural isomer of ABA [S-(+)-ABA] was an effective inducer at a concentration as low as 1 × 10−7 M , but a concentration of greater than 1 × 10−4 M was required for induction by [R-(—)-ABA]. Moreover, analogs with the same configuration at C-l1 as that of natural ABA were more effective for induction of expression from the Em-uidA . insert at 1 × 10−4 M than were their enamiomers. Plasnud pBI511. carrying the chloramphenicol acety] transferase (CAT) gene driven by the constitutively expressed, tandemly duplicated cauliflower mosaic virus 35S promoter, was co-electroporated with pBM113Kp for monitoring Ihe influence of addition of exogenous ABA or ABA analogs on heterologous gene expression in protoplasts. CAT activity was not significantly affected by the presence or absence of ABA or the analogs used. 相似文献
98.
Molecular evolution in the gnd locus of Salmonella enterica 总被引:3,自引:0,他引:3
The gnd gene, the structural gene for 6-phosphogluconate dehydrogenase, was
sequenced and analyzed in 34 isolates from different serovars of the seven
subspecies of Salmonella enterica to provide comparative information on the
evolution in this gene, which has been studied extensively in Escherichia
coli. The gene tree obtained by the neighbor- joining method in general
gave separate branches for each subspecies, with the few exceptions readily
explained by recombination. There is evidence of recombination involving
transfer of long (more than 400 bp) and short (30-150 bp) segments of DNA.
Four of the six long-segment transfers detected are at the 5' end of the
gene, and in all four cases a variant of the chi sequence is located close
to the recombination junction and appears to have mediated the
recombination events. We suggest that in these four cases and in a fifth
case with intersubspecies transfer of the whole gnd gene, the adjacent rfb
(O antigen) locus may have been transferred in the same event. The
estimates of the number of synonymous substitutions per synonymous site,
KS, and the number of nonsynonymous substitutions per nonsynonymous site,
KA, within the E. coli and S. enterica gnd genes, and also between the two
species show an interesting distribution, with KS being lower toward the
ends of the gene and KA in particular being lower in the first than in the
second domain. In S. enterica, synonymous sites also seem to be subjected
to negative selection. The ratio of KA to KS was higher within S. enterica
and E. coli than between them, which may indicate that intraspecies
variation is essentially between clones and that mildly deleterious
mutations can be fixed within clones, which would thus raise KA within
species.
相似文献
99.
David I. Dunstan Stephanie Berry Cheryl A. Bock 《In vitro cellular & developmental biology. Plant》1994,30(3):156-159
Summary We investigated abscisic acid (ABA) metabolism among Norway and white spruce somatic embryo cultures which exhibited differences
in maturation response when placed on racemic abscisic acid [(±)-ABA]. Differences in metabolic rate among the spruce genotypes
could affect the ABA pool available for the maturation process, and might therefore be responsible for the differences in
maturation response. The production of cotyledonary (stage 3) somatic embryos in cultures (genotypes) of Norway spruce (PA86:26A
and PA88:25B) and of white spruce (WS1F cryoD and WS46) was compared. In each species pair one of the two genotypes failed
to show stage 3 embryo development (respectively, PA88:25B and WS46). The investigation of ABA metabolism of each species
pair showed that no substantial differences in ABA consumption or in the production of metabolites occurred. In each case
ABA was metabolized to phaseic acid and dihydrophaseic acid over the 42-day culture period, metabolites were recoverable from
the agar-solidified medium, and the sum of residual ABA and metabolites were equivalent to the ABA initially supplied. The
results indicate that the process of ABA metabolism occurs essentially independently of somatic embryo maturation.
NRCC no. 37345. 相似文献
100.
Karel Mokany Simon Ferrier Sean R. Connolly Piers K. Dunstan Elizabeth A. Fulton Michael B. Harfoot Thomas D. Harwood Anthony J. Richardson Stephen H. Roxburgh Jörn P. W. Scharlemann Derek P. Tittensor David A. Westcott Brendan A. Wintle 《Oikos》2016,125(1):10-19
There is increasing reliance on ecological models to improve our understanding of how ecological systems work, to project likely outcomes under alternative global change scenarios and to help develop robust management strategies. Two common types of spatiotemporally explicit ecological models are those focussed on biodiversity composition and those focussed on ecosystem function. These modelling disciplines are largely practiced separately, with separate literature, despite growing evidence that natural systems are shaped by the interaction of composition and function. Here we call for the development of new modelling approaches that integrate composition and function, accounting for the important interactions between these two dimensions, particularly under rapid global change. We examine existing modelling approaches that have begun to combine elements of composition and function, identifying their potential contribution to fully integrated modelling approaches. The development and application of integrated models of composition and function face a number of important challenges, including biological data limitations, system knowledge and computational constraints. We suggest a range of promising avenues that could help researchers overcome these challenges, including the use of virtual species, macroecological relationships and hybrid correlative‐mechanistic modelling. Explicitly accounting for the interactions between composition and function within integrated modelling approaches has the potential to improve our understanding of ecological systems, provide more accurate predictions of their future states and transform their management. Synthesis There is increasing attention from researchers and policy makers around the world on both assessing and projecting the state of the planet's biodiversity, its ecosystems and the essential services they provide to society. However, existing modelling approaches largely ignore the interactions between biodiversity composition and ecosystem function. We highlight the key challenges and potential solutions to developing integrated models of composition and function. Such models will require a new effort and focus from ecologists, yet the benefits are likely to be substantial, including better informing the management of natural systems at regional, national and international scales. 相似文献