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991.
A comparative study of just cadmium (Cd) or heat and their combination treatments on some physiological parameters and the antioxidant systems in transgenic rice (Oryza sativa L. cv. Zhonghua No.11) carrying glutathione-S-transferase (GST, EC. 2.5.1.18) and catalasel (CAT1, EC. 1.11.1.6) and non-transgenics was conducted. The results revealed improved resistance in the transgenics to Cd and the combined Cd and heat stress than non-transgenics. Data showed that the activities of CAT, GST, superoxide dismutase (EC.1.15.1.1) and all components of the ascorbate-glutatbione cycle measured in the stressed transgenics shoots are significantly different from those of non-transgenics. Results indicated that co-expression of GST and CAT1 had an important effect on the antioxidant system, in particular, the whole ascorbate-glutathione cycle. The less oxidative damage induced by Cd and the stress combination in the transgenics resulted not only from the GST and CAT1 transgene but also from the coordination of the whole ascorbate-glutathione cycle. 相似文献
992.
D. Karakashev S. M. Kotay E. Trably I. Angelidaki 《Journal of applied microbiology》2009,106(3):1041-1049
Aims: The aim of this study was to enrich, characterize and identify strict anaerobic extreme thermophilic hydrogen (H2 ) producers from digested household solid wastes.
Methods and Results: A strict anaerobic extreme thermophilic H2 producing bacterial culture was enriched from a lab-scale digester treating household wastes at 70°C. The enriched mixed culture consisted of two rod-shaped bacterial members growing at an optimal temperature of 80°C and an optimal pH 8·1. The culture was able to utilize glucose, galactose, mannose, xylose, arabinose, maltose, sucrose, pyruvate and glycerol as carbon sources. Growth on glucose produced acetate, H2 and carbon dioxide. Maximal H2 production rate on glucose was 1·1 mmol l−1 h−1 with a maximum H2 yield of 1·9 mole H2 per mole glucose. 16S ribosomal DNA clone library analyses showed that the culture members were phylogenetically affiliated to the genera Bacillus and Clostridium. Relative abundance of the culture members, assessed by fluorescence in situ hybridization, were 87 ± 5% and 13 ± 5% for Bacillus and Clostridium , respectively.
Conclusions: An extreme thermophilic, strict anaerobic, mixed microbial culture with H2 -producing potential was enriched from digested household wastes.
Significance and Impact of the Study: This study provided a culture with a potential to be applied in reactor systems for extreme thermophilic H2 production from complex organic wastes. 相似文献
Methods and Results: A strict anaerobic extreme thermophilic H
Conclusions: An extreme thermophilic, strict anaerobic, mixed microbial culture with H
Significance and Impact of the Study: This study provided a culture with a potential to be applied in reactor systems for extreme thermophilic H
993.
Aims: To determine conditions for generation and recovery of Bacillus subtilis spore populations heavily damaged by moist heat treatment.
Methods and Results: Bacillus subtilis spores were treated with moist heat and spore viability was assessed on different media. A rich medium and several minimal media gave similar spore recoveries after moist heat treatment, but lack of glucose in minimal media greatly decreased spore recovery. High NaCl levels also greatly decreased the recovery of moist heat-treated spores on minimal media, and addition of good osmoprotectants reversed this effect. Moist heat treatment did not decrease spore recovery on minimal media with high salt through DNA damage or by eliminating spore germination, but by affecting spore outgrowth.
Conclusions: Conditions for generating B. subtilis spore populations with high levels of conditional moist heat damage have been determined. The major conditional damage appears to be in spore outgrowth, perhaps because of damage to one or more important metabolic enzymes.
Significance and Impact of the Study: This work has provided new insight into the mechanism of B. subtilis spore killing by moist heat. 相似文献
Methods and Results: Bacillus subtilis spores were treated with moist heat and spore viability was assessed on different media. A rich medium and several minimal media gave similar spore recoveries after moist heat treatment, but lack of glucose in minimal media greatly decreased spore recovery. High NaCl levels also greatly decreased the recovery of moist heat-treated spores on minimal media, and addition of good osmoprotectants reversed this effect. Moist heat treatment did not decrease spore recovery on minimal media with high salt through DNA damage or by eliminating spore germination, but by affecting spore outgrowth.
Conclusions: Conditions for generating B. subtilis spore populations with high levels of conditional moist heat damage have been determined. The major conditional damage appears to be in spore outgrowth, perhaps because of damage to one or more important metabolic enzymes.
Significance and Impact of the Study: This work has provided new insight into the mechanism of B. subtilis spore killing by moist heat. 相似文献
994.
Aims: To compare conventional plate counting and indirect conductimetry as techniques for ranking the resistance of Salmonella spp. to processing stressors.
Methods and Results: Forty Salmonella isolates were subjected to three separate stressors used in food processing; irradiation, heat and high hydrostatic pressure (HHP). Total viable counts (TVC) using conventional plate counts and time to detection (TTD) using indirect conductimetry were determined. A significant negative correlation between TVC and TTD was seen with irradiation ( P < 0·01) and heat ( P < 0·05) but not HHP.
Conclusions: For a group of salmonellas, indirect conductimetry can rapidly determine a ranking of isolate sensitivity to irradiation and heat. However, for HHP, the results indicated that conventional plate counting alone cannot be used to determine sensitivity.
Significance and Impact of the Study: The resistance of micro-organisms to processing systems must be ranked to allow the selection of appropriate isolates for process validation. TTD measurements allow rapid screening of salmonellas to rank isolates for resistance to irradiation and heat stress. However, following HHP, the TVC of survivors is independent of the time required for growth to a set cell density and therefore it cannot be used as the sole measure of relative stress resistance. 相似文献
Methods and Results: Forty Salmonella isolates were subjected to three separate stressors used in food processing; irradiation, heat and high hydrostatic pressure (HHP). Total viable counts (TVC) using conventional plate counts and time to detection (TTD) using indirect conductimetry were determined. A significant negative correlation between TVC and TTD was seen with irradiation ( P < 0·01) and heat ( P < 0·05) but not HHP.
Conclusions: For a group of salmonellas, indirect conductimetry can rapidly determine a ranking of isolate sensitivity to irradiation and heat. However, for HHP, the results indicated that conventional plate counting alone cannot be used to determine sensitivity.
Significance and Impact of the Study: The resistance of micro-organisms to processing systems must be ranked to allow the selection of appropriate isolates for process validation. TTD measurements allow rapid screening of salmonellas to rank isolates for resistance to irradiation and heat stress. However, following HHP, the TVC of survivors is independent of the time required for growth to a set cell density and therefore it cannot be used as the sole measure of relative stress resistance. 相似文献
995.
Sunitha Rangaraju David Hankins Irina Madorsky Evgenia Madorsky Wei-Hua Lee Christy S. Carter Christiaan Leeuwenburgh Lucia Notterpek 《Aging cell》2009,8(2):178-191
Peripheral nerves from aged animals exhibit features of degeneration, including marked fiber loss, morphological irregularities in myelinated axons and notable reduction in the expression of myelin proteins. To investigate how protein homeostatic mechanisms change with age within the peripheral nervous system, we isolated Schwann cells from the sciatic nerves of young and old rats. The responsiveness of cells from aged nerves to stress stimuli is weakened, which in part may account for the observed age-associated alterations in glial and axonal proteins in vivo . Although calorie restriction is known to slow the aging process in the central nervous system, its influence on peripheral nerves has not been investigated in detail. To determine if dietary restriction is beneficial for peripheral nerve health and glial function, we studied sciatic nerves from rats of four distinct ages (8, 18, 29 and 38 months) kept on an ad libitum (AL) or a 40% calorie restricted diet. Age-associated reduction in the expression of the major myelin proteins and widening of the nodes of Ranvier are attenuated by the dietary intervention, which is paralleled with the maintenance of a differentiated Schwann cell phenotype. The improvements in nerve architecture with diet restriction, in part, are underlined by sustained expression of protein chaperones and markers of the autophagy–lysosomal pathway. Together, the in vitro and in vivo results suggest that there might be an age-limit by which dietary intervention needs to be initiated to elicit a beneficial response on peripheral nerve health. 相似文献
996.
城市地表温度与关键景观要素的关系 总被引:1,自引:0,他引:1
利用Landsat ETM+遥感影像,提取上海市外环线范围内的地表温度、不透水面率、归一化差值植被指数、改进的归一化差异水体指数,定量研究地表温度与城市关键景观类型之间的关系.结果表明:地表温度与不透水面率呈显著的线性正相关( R2=0.837);地表温度与归一化差值植被指数和改进的归一化差异水体指数呈非线性关系,但地表温度与正的归一化差值植被指数和正的改进的归一化差值水体指数呈显著线性关系.鉴于归一化差值植被指数和改进的归一化差异水体指数大于0时才能真正代表植被和水体,因此,建议今后研究地表温度时使用正的归一化差值植被指数和改进的归一化差异水体指数;地表温度与不透水面率、归一化差值植被指数和改进的归一化差值水体指数的多元线性回归分析表明,不透水面起着增温作用,植被、水体起降温作用,植被较水体的降温作用大. 相似文献
997.
热休克蛋白Gp96属于HSP90家族,是内质网中最丰富的蛋白质之一,在细胞内发挥着分子伴侣的作用。在天然免疫中,Gp96则通过与Toll样受体等相互作用刺激抗原呈递细胞 (如DC等) 产生各种细胞因子激活免疫系统;而在获得性免疫中,Gp96抗原胶通过抗原交叉呈递给MHC-I类分子,诱发机体抗原特异性细胞毒T细胞免疫应答,清除病原物感染和肿瘤;近年来的研究还发现Gp96具有免疫佐剂的功能。以下从Gp96的生物学特性、免疫学机制以及其在抗病原感染和抗肿瘤免疫中的应用等方面做一小结,为设计以Gp96-抗原肽为新一代疫苗的临床研究提供理论基础。 相似文献
998.
Ambient temperatures have increased since the beginning of the century and are predicted to continue rising under climate change. Such increases in temperature can cause heat stress: a severe threat to wheat production in many countries, particularly when it occurs during reproductive and grain-filling phases. Heat stress reduces plant photosynthetic capacity through metabolic limitations and oxidative damage to chloroplasts, with concomitant reductions in dry matter accumulation and grain yield. Genotypes expressing heat shock proteins are better able to withstand heat stress as they protect proteins from heat-induced damage. Heat tolerance can be improved by selecting and developing wheat genotypes with heat resistance. Wheat pre-breeding and breeding may be based on secondary traits like membrane stability, photosynthetic rate and grain weight under heat stress. Nonetheless, improvement in grain yield under heat stress implies selecting genotypes for grain size and rate of grain filling. Integrating physiological and biotechnological tools with conventional breeding techniques will help to develop wheat varieties with better grain yield under heat stress during reproductive and grain-filling phases. This review discusses the impact of heat stress during reproductive and grain-filling stages of wheat on grain yield and suggests strategies to improve heat stress tolerance in wheat. 相似文献
999.
1000.
兰州中心城区用地扩展及其热岛响应的遥感分析 总被引:5,自引:0,他引:5
以兰州中心城区为研究区,以1978、1993、2001和2010年的Landsat MSS/TM/ETM+影像为数据源,采用NDBI-SAVI指数相结合的方法,提取建设用地信息,利用热红外波段的单窗算法反演城市地表温度.结合城市热岛比例指数和地表温度分级,定量研究城镇用地扩张对城市热环境的影响.结果表明:兰州中心城区建设用地在1978-2010年的30余年间面积由87.47 km2增加到172.61 km2,增幅近l倍.城市扩展与热岛扩展趋势具有空间一致性,在城市扩张的同时,城区地表温度逐渐上升,城市热岛面积不断扩大. 相似文献