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111.
To maintain protein homoeostasis, animals have developed stress response pathways such as the ubiquitin proteasome system (UPS). Joshi and colleagues have demonstrated that in Caenorhabditis elegans, dopamine release from neurons acts on receptors in the epithelia to modulate protein turnover, by controlling the expression of regulators of the xenobiotic stress response. Dopamine receptor mutants challenged with pathogenic bacteria were defective in protein turnover and were also more sensitive to infection thus highlighting a role for monoamine signalling in innate immunity and stress responses. 相似文献
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The histological effect on and stress response of post juvenile Clarias gariepinus exposed to Qua Iboe crude oil and rig wash were investigated. Fish weighing 60–90 g and measuring 16–18 cm were exposed for 7–28 days to 8.00 ml?1 Qua Iboe crude oil and 0.0018 ml–1 rig wash, both being 0.1 of the 96 hr LC50. Blood samples of C. gariepinus were collected every seven days and evaluated for stress by measuring cortisol concentration. The gills and liver were studied and scored for Gill Alteration Index (GAI) and Hepatic Alteration Index (HAI), respectively. There was an increase in cortisol level up to the 7th and 14th day among the group exposed to Qua Iboe crude oil, with a decrease on the 21st and 28th day. The rig wash group increased in cortisol level up to the 7th day and decreased slightly on the 14th day, after which the trend became irregular. The toxic effects of the Qua Iboe crude oil and rig wash were time dependent, as shown by the histopathological alteration index (HAI) of gill and liver. After 28 days of exposure, the gills had irreparable damage due to high frequency of cellular necrosis and degeneration, whereas the liver had from moderate to severe damage due to the high frequency of cellular degeneration and inflammation. Qua Iboe crude oil and rig wash are both toxic to C. gariepinus, therefore their indiscriminate discharge to the environment must be discouraged. 相似文献
115.
Frick NT Bystriansky JS Ip YK Chew SF Ballantyne JS 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2008,151(1):93-101
The potential importance of lipids and ketone bodies as fuels in the African lungfish, Protopterus dolloi, and the role of oxidative metabolism, were examined under control, fasted and aestivated conditions. In aestivating but not fasting lungfish, the activities of citrate synthase (CS) and cytochrome c oxidase (CCO) (enzymes of oxidative metabolism) showed tissue-specific changes. Significant reductions in CS activity occurred in the kidney, heart, gill and muscle, and in CCO in the liver and kidney tissues. Aestivation, but not fasting, also had a tissue-specific effect on mitochondrial state 3 respiration rates (using succinate as a substrate), with a >50% reduction in the liver, yet no change within muscle mitochondria. There is no indication that enzymes involved in lipid catabolism are up-regulated during periods of fasting or aestivation; however, both 3-hydroxyacyl CoA dehydrogenase (HOAD) and carnitine palmitoyl CoA transferase (CPT) activities were sustained in the liver despite the approximately 42% reduction in CCO activity, potentially indicating lipid metabolism is of importance during aestivation. Lungfish are able to utilize both the d- and l-stereoisomers of the ketone body beta-hydroxybutyrate (beta-HB); however, beta-HB does not appear to be an important fuel source during aestivation or fasting as no changes were observed in beta-HB tissue levels. This study demonstrates that an important aspect of metabolic depression during aestivation in lungfish is the tissue-specific down regulation of enzymes of aerobic metabolism while maintaining the activities of enzymes in pathways that supply substrates for aerobic metabolism. 相似文献
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Many woody plant species in fire disturbed communities survive disturbance events by resprouting. The resprouting life history
is predicted to be costly to plants as resources are diverted into storage for post-fire regrowth rather than allocated to
current growth, and resprouting species typically grow more slowly than seeder species (species that do not resprout after
disturbance events). Differences in allocation to current growth are also predicted to make resprouter species poorer competitors
compared to seeder species. We tested the predictions that the evolution of a resprouter life history is associated with slow
growth, increased allocation to storage, and low competitive ability in woody plant seedlings. We grew eight phylogenetically
independent pairs of seeder and resprouter species in competition and no competition treatments in a field experiment near
Sydney, Australia. The presence of competitors reduced plant growth rates across taxa and fire response life histories. However,
relative to seeder species, resprouter species were not slower growing, they did not allocate more resources to storage, and
they did not have lower competitive abilities. We propose that differences in resource allocation to storage are not responsible
for differences in growth rate and competitive ability. Rather, growth rate and competitive ability in seedlings are associated
with key aspects of plant life history such as life-span and body size at maturity. These traits that are sometimes, but not
always, related to fire response life histories. 相似文献
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Aline Gomez Maqueo Chew Niels-Ulrik Frigaard Donald A. Bryant 《Photosynthesis research》2009,101(1):21-34
The first committed step in the biosynthesis of (bacterio-)chlorophyll is the insertion of Mg2+ into protoporphyrin IX by Mg-chelatase. In all known (B)Chl-synthesizing organisms, Mg-chelatase is encoded by three genes
that are homologous to bchH, bchD, and bchI of Rhodobacter spp. The genomes of all sequenced strains of green sulfur bacteria (Chlorobi) encode multiple bchH paralogs, and in the genome of Chlorobaculum tepidum, there are three bchH paralogs, denoted CT1295 (bchT), CT1955 (bchS), and CT1957 (bchH). Cba. tepidum mutants lacking one or two of these paralogs were constructed and characterized. All of the mutants lacking only one of these
BchH homologs, as well as bchS bchT and bchH bchT double mutants, which can only produce BchH or BchS, respectively, were viable. However, attempts to construct a bchH
bchS double mutant, in which only BchT was functional, were consistently unsuccessful. This result suggested that BchT alone is
unable to support the minimal (B)Chl synthesis requirements of cells required for viability. The pigment compositions of the
various mutant strains varied significantly. The BChl c content of the bchS mutant was only ~10% of that of the wild type, and this mutant excreted large amounts of protoporphyrin IX into the growth
medium. The observed differences in BChl c production of the mutant strains were consistent with the hypothesis that the three BchH homologs function in end product
regulation and/or substrate channeling of intermediates in the BChl c biosynthetic pathway.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
120.
Catalytic cracking of crude palm oil (CPO) and used palm oil (UPO) were studied in a transport riser reactor for the production of biofuels at a reaction temperature of 450 °C, with residence time of 20 s and catalyst-to-oil ratio (CTO) of 5 g g?1. The effect of HZSM-5 (differrent Si/Al ratios), beta zeolite, SBA-15 and AlSBA-15 were studied as physically mixed additives with cracking catalyst Rare earth-Y (REY). REY catalyst alone gave 75.8 wt% conversion with 34.5 wt% of gasoline fraction yield using CPO, whereas with UPO, the conversion was 70.9 wt% with gasoline fraction yield of 33.0 wt%. HZSM-5, beta zeolite, SBA-15 and AlSBA-15 as additives with REY increased the conversion and the yield of organic liquid product. The transport riser reactor can be used for the continuous production of biofuels from cracking of CPO and UPO over REY catalyst. 相似文献