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341.
The serine/threonine O-linked carbohydrates GalNAc alpha and Gal beta 1-3GalNAc alpha, referred to as Tn and T antigens, respectively, appear to be more prevalent in some human carcinomas than in surrounding tissues. Tn/T antigens may represent incomplete synthesis of O-linked oligosaccharides, due to decreased activity of specific glycosyltransferases, or alternatively, increased glycosidases activity in tumors which may expose these internal O-linked oligosaccharide sequences. To explore these possibilities, we measured UDP-Gal:GalNAc alpha-R beta 1-3 galactosyltransferase (beta 3Gal-T) and Gal beta 1-3GalNAc alpha-R beta 1-3 galactosidase in a series of human breast tumors. In addition, glycoproteins extracted from the tumors were separated by SDS-PAGE and stained with the lectins HPA (GalNAc alpha-R reactive) and PNA (Gal beta-3GalNAc alpha-R reactive). The relative levels of HPA- to PNA-reactive glycoproteins in the carcinomas correlated inversely with beta 3Gal-T activities. The results suggest that Tn antigen expression in human breast carcinoma is due in part to low beta 3Gal-T activity, a situation similar to that observed previously in haematopoietic cells of individuals with a condition called Tn syndrome. 相似文献
342.
Prosopis glandulosa var. torreyana accounts for nearly 90% of the total plant cover in a mesquite woodland community near Harper's Well along the southern margin of the Salton Sea in the Sonoran Desert of California. Total above-ground biomass in ten individuals studied in detail ranged from 43–760 kg per plant and 1.9–8.5 kg m-2 canopy area. Stand biomass ranged locally from a high of 23,000 kg ha-1 near the wash to 3,500 kg ha-1 in the fringe of this mesquite stand. Net above-ground primary production for 1980 had a mean of 2.2 kg m-2 canopy for shrub forms and 5.3 kg m-2 canopy for tree forms. Mean Prosopis stand production for 1980 was 3,650 kg ha-1, an extremely high value for desert communities. This level of production is particularly high in relation to the low mean annual precipitation of approximately 70 mm. New woody tissues in trunk and branches accounted for 51.5% of the allocation of productivity in Prosopis, a remarkably high woody allocation for a desert plant. Only 33.6% of net primary production was allocated to leaves. 相似文献
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S Yousefi A Ghazinouri N Vaziri J Tilles G Carandang T Cesario 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1990,194(2):114-118
Somatostatin (SMS) is a tetradecapeptide which can inhibit the secretion of a number of peptides produced by the endocrine or nervous systems. SMS 201-995 (octreotide) is a somatostatin analogue with very potent somatostatin activities. We have been investigating the effects of both SMS and octreotide on the production of human interferon (IFN). We obtained human peripheral blood mononuclear cells from normal donors and induced them to produce IFN in the presence or absence of a number of peptides possessing somatostatin activities. SMS and octreotide were shown to inhibit the secretion of INF-gamma but not IFN-alpha. Concentrations of 10(-6) M were shown to decrease yields when Concanavalin A or phytohemagglutin were used as the inducer. Higher concentrations had a progressively greater effect. No effects were observed on IFN-gamma production if interleukin 2, ionomycin, or various natural antigens were used to induce the cells. The 28-amino acid form of somatostatin had some effects on gamma IFN yields but the first 14-amino acid fragment of this peptide moiety did not. No effect of any of these compounds was observed on IFN bioactivity. These studies indicate SMS may have some regulatory action on the secretion of immunomodulators in vitro but the concentrations required are well above those encountered under physiologic circumstances, suggesting SMS may not play an important regulatory role governing such secretion in vivo. 相似文献
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AbstractPerceptions of the populace play a central and decisive role in advancing pro-environmental policies. To study attitudes and perceptions towards environmental measures, we apply several items of New Ecological Paradigm (NEP) and Value-Belief-Norm (VBN) theories to cross-examine the public perceptions of climate change in the urban city-state of Singapore through analysis of quantitative questionnaires and qualitative semi-structured interviews. The perceptions were explored about ecological orientation (two dimensions of NEP: level of concern, self-reported knowledge) and environmental behavior (two dimensions of VBN: acceptance and support of national adaptation measures, confidence in adaptation). There is a moderate to high concern for climate change, in general, and sea level rise and flooding, in particular, and the concern is expected to increase in the future. Individuals who indicated a higher level of concern are likely to be more accepting and supportive of climate change measures. Also, while the majority of the populace are amenable to legislative measures from the government, such as enacting pro-environmental laws and more are agreeable to accepting cuts on living standards, as opposed to paying more in prices and taxes. Ecological orientation does not translate directly into environmental behavior, highlighting the gulf between perception and behavior in Singapore. 相似文献
347.
AbstractHuman health has been identified to be affected more significantly by indoor air quality. Among numerous pollutants present in indoor air, formaldehyde (FA) is of great concern because of its highly hazardous nature. The concentrations of FA were determined from 20 newly decorated homes in the city of Gonabad, Iran during 2015. It was found that the indoor air levels of FA in all the sampled houses were exceptionally high in the range of 21 to 360 µg/m3 (mean of 149.3 µg/m3). If the 24-h average concentrations of FA measured from those sites were concerned, nearly 40% of them were seen to exceed the WHO guideline values (i.e., 100 µg/m3). One of the important reasons for the high concentrations could be low air exchange rates in those houses (e.g., from 0.18 to 0.37?h?1), high levels of humidity in the newly decorating houses and stronger sources in the indoor environment. Furthermore, its pollution in homes with natural ventilation was seen to be much higher than those of mechanical ventilation. Due to high levels of indoor FA, more effective control procedures should be developed and employed to reduce the risk associated with formaldehyde exposure. 相似文献