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981.
982.
Interactions between Carbon and Nitrogen Metabolism in Fibrobacter succinogenes S85: a 1H and 13C Nuclear Magnetic Resonance and Enzymatic Study 下载免费PDF全文
Christelle Matheron Anne-Marie Delort Genevieve Gaudet Tibor Liptaj Evelyne Forano 《Applied microbiology》1999,65(5):1941-1948
The effect of the presence of ammonia on [1-13C]glucose metabolism in the rumen fibrolytic bacterium Fibrobacter succinogenes S85 was studied by 13C and 1H nuclear magnetic resonance (NMR). Ammonia halved the level of glycogen storage and increased the rate of glucose conversion into acetate and succinate 2.2-fold and 1.4-fold, respectively, reducing the succinate-to-acetate ratio. The 13C enrichment of succinate and acetate was precisely quantified by 13C-filtered spin-echo difference 1H-NMR spectroscopy. The presence of ammonia did not modify the 13C enrichment of succinate C-2 (without ammonia, 20.8%, and with ammonia, 21.6%), indicating that the isotopic dilution of metabolites due to utilization of endogenous glycogen was not affected. In contrast, the presence of ammonia markedly decreased the 13C enrichment of acetate C-2 (from 40 to 31%), reflecting enhanced reversal of the succinate synthesis pathway. The reversal of glycolysis was unaffected by the presence of ammonia as shown by 13C-NMR analysis. Study of cell extracts showed that the main pathways of ammonia assimilation in F. succinogenes were glutamate dehydrogenase and alanine dehydrogenase. Glutamine synthetase activity was not detected. Glutamate dehydrogenase was active with both NAD and NADP as cofactors and was not repressed under ammonia limitation in the culture. Glutamate-pyruvate and glutamate-oxaloacetate transaminase activities were evidenced by spectrophotometry and 1H NMR. When cells were incubated in vivo with [1-13C]glucose, only 13C-labeled aspartate, glutamate, alanine, and valine were detected. Their labelings were consistent with the proposed amino acid synthesis pathway and with the reversal of the succinate synthesis pathway. 相似文献
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The present study aimed to dissect tree architectural plasticity into genetic, ontogenetic and environmental effects over
the first 4 years of growth of an apple F1 progeny by means of quantitative traits loci (QTL) mapping. Both growth and branching
processes were phenotyped on the consecutive annual shoots of different axes within a tree. For each studied trait, predicted
values (best linear unbiased predictors, BLUPs) of the genotypic (G) effect or its interaction with tree age (G×A) and climatic
year (G×Y) were extracted from mixed linear models of repeated data. These BLUPs, which are independent from autocorrelations
between repeated measurements, were used for QTL mapping. QTL detection power was improved by this two-step approach. For
each architectural process, numerous QTLs were detected and some particularly interesting co-localised in common genomic regions,
for internode lengthening, top diameter, and number and percentage of axillary shoots. When several QTLs were detected for
a given trait, global models were estimated, which explained a maximum of 40% of the total variance for both internode length
and top diameter and 28% for branching. QTLs detected for BLUPs of G×Y effects were interpreted as resulting from the interaction
between genetic maximal potential of growth and climatic factors, while those for G×A effects were interpreted in relation
to tree ontogeny. Most of the latter ones were found to be concomitant with key development stages during which the trait
average started to decrease, but with different magnitudes depending on genotype.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
986.
Catherine Nury Sarah Bregant Bertrand Czarny Fannely Berthon Evelyne Cassar-Lajeunesse Vincent Dive 《The Journal of biological chemistry》2013,288(8):5636-5644
Matrix metalloproteases (MMPs) have attracted considerable attention as critical mediators of pathological tissue remodeling processes. However it remains an unresolved challenge to detect their active forms in biological samples. To prove the efficacy of a recently developed MMP activity-based probe, we examined the content in MMP active forms of bronchoalveolar lavage fluids (BALf) from male C57BL/6 mice exposed to ultrafine carbon black nanoparticles, a model of chronic obstructive pulmonary disease. This probe was shown to label proteins, mostly expressed in BALf of mice exposed to nanoparticles. Using competition assays with a selective MMP-12 inhibitor as well as MMP-12 knock-out mice, one of these proteins was identified as the active form of the catalytic domain of MMP-12. This new probe can detect the active form of MMP-12 down to a threshold of 1 fmol. Radioactive counting showed the concentration of the active form of MMP-12 to be around 1 fmol/μl in BALf from nanoparticle-treated mice. A less sensitive probe would therefore not have detected MMP-12. As the probe can detect other MMPs in the femtomolar range, it is a potentially powerful tool for monitoring the levels of MMP active forms in various diseases. 相似文献
987.
Evelyne Véricel Michel Narce Lionel Ulmann Jean-Pierre Poisson Michel Lagarde 《Molecular and cellular biochemistry》1994,132(1):25-29
The effects of age and hypertension on the antioxidant defence systems and the lipid peroxidation in rat isolated hepatocytes were studied. Four different age groups (1,3,6 and 12 months) were considered in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Age-associated changes were observed on vitamin E status, glutathione (GSH) level, MDA formation and glutathione peroxidase (GSH-Px) activity in both strains. Maximal levels or activities of these parameters were found at 3 and 6 months, except for MDA which was low at 3 months. Then, a fall was observed at 12-month-old compared to 6-month values. In addition, GSH-Px activity was significantly lower in SHR than in WKY rats, except at the age of one month. The decrease of this enzyme activity could induce an increased cellular generation of radical species and lipid peroxidation, which might be link to hypertension. 相似文献
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Hadrien Fanton Evelyne Franquet Maxime Logez Nicolas Kaldonski 《Freshwater Biology》2020,65(10):1718-1725
- Salt pollution of freshwater ecosystems represents a major threat to biodiversity, and particularly to interactions between free-living species and their associated parasites. Acanthocephalan parasites are able to alter their intermediate host's phenotype to reach final hosts, but this process could be affected by salt pollution, thereby compromising survival of the parasite.
- We experimentally assessed the impact of salt on the extended phenotype of the parasite Pomphorhynchus laevis in their intermediate host, the amphipod Gammarus pulex, based on three amphipod behaviours: distance covered in flowing water, phototaxis, and geotaxis. We hypothesised that: (1) salt pollution negatively affected the behaviour of uninfected gammarids, and (2) that P. laevis could maintain their capacity to manipulate their host despite this pollution.
- All three amphipod behaviours were altered by P. laevis: infected G. pulex covered a greater distance, were less photophobic and were more attracted to the water surface than uninfected amphipods, in control or salt-polluted water. However, salinity reduced distance covered in flowing water and increased attraction to the water surface of uninfected and infected G. pulex. For the phototaxis behaviour, P. laevis enhanced this capacity of manipulation in salt-polluted water compared to control water.
- Pomphorhynchus laevis can still manipulate the behaviour of their intermediate host in salt-polluted water. Acanthocephalan parasites have not been known to be able to manipulate their intermediate host when under pollution stress. Trophic interactions, but not the chances of parasite transmission to their definitive host, appear to be affected by salt pollution.
- Our study indicates that behavioural modifications induced by complex lifecycle parasites should be more considered in the context of growing concentrations of chemical pollutants in some freshwater ecosystems. Interspecific interactions, and particularly host–parasite relationships, are a key component of ecosystem stability and their alteration could result in major changes in energy flow.
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