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121.
122.
Development of a stepwise aeration control strategy for efficient docosahexaenoic acid production by Schizochytrium sp. 总被引:1,自引:0,他引:1
Lu-Jing Ren Xiao-Jun Ji He Huang Liang Qu Yun Feng Qian-Qian Tong Ping-Kai Ouyang 《Applied microbiology and biotechnology》2010,87(5):1649-1656
The effect of aeration on the performance of docosahexaenoic acid (DHA) production by Schizochytrium sp. was investigated in a 1,500-L bioreactor using fed-batch fermentation. Six parameters, including specific growth rate,
specific glucose consumption rate, specific lipid accumulation rate, cell yield coefficient, lipid yield coefficient, and
DHA yield coefficient, were used to understand the relationship between aeration and the fermentation characteristics. Based
on the information obtained from the parameters, a stepwise aeration control strategy was proposed. The aeration rate was
controlled at 0.4 volume of air per volume of liquid per minute (vvm) for the first 24 h, then shifted to 0.6 vvm until 96 h,
and then switched back to 0.4 vvm until the end of the fermentation. High cell density (71 g/L), high lipid content (35.75 g/L),
and high DHA percentage (48.95%) were achieved by using this strategy, and DHA productivity reached 119 mg/L h, which was
11.21% over the best results obtained by constant aeration rate. 相似文献
123.
Jia-En Zhang Jin-Ling Liu Ying Ouyang Bao-Wen Liao Ben-Liang Zhao 《Ecological Engineering》2010,36(6):807-812
Mangrove wetlands are important in the removal of nutrients, heavy metals, and organic pollutants from wastewater within estuarine systems due to the presence of oxidized and reduced conditions, periodic flooding by incoming and outgoing tides, and high clay and organic matter content. This study investigated the removal efficiency of nutrients and heavy metals from wastewater by the mangrove Sonneratia apetala Buch-Ham in a simulated wetland. Eight different treatments, namely, three concentration levels of wastewaters, with and without planting of the mangrove species, and one control (with salted water) each for both with and without planting of the mangrove species, were employed in this study. Results showed that the amounts of total mangrove biomass from different treatments were in the following order: PL-TW (planted with ten times higher-than-normal wastewater concentration) > PL-FW (planted with five times higher-than-normal wastewater concentration) > PL-SW (planted with normal wastewater concentration) > PL-NW (planted with no wastewater), whereas the magnitude of the heavy metal contents in the biomass was in the following order: Cu > Pb > Cd > Zn. Very good linear correlations existed between the biomass and the nutrients or heavy metals. The Sonneratia apetala Buch-Ham species had its own selectivity for uptake of heavy metals regardless of the initial heavy metal contents and was more effective in the removal of nutrients than heavy metals. Our study suggested that mangrove wetlands with Sonneratia apetala Buch-Ham species had great potential for the removal of nutrients and heavy metals in coastal areas. 相似文献
124.
Xuwu Sun Min Ouyang Jinkui Guo Jinfang Ma Congming Lu Zach Adam Lixin Zhang 《The Plant journal : for cell and molecular biology》2010,62(2):240-249
DegP proteases have been shown to possess both chaperone and protease activities. The proteolytic activities of chloroplast DegP‐like proteases have been well documented. However, whether chloroplast Deg proteases also have chaperone activities has remained unknown. Here we show that chloroplast Deg1 also has chaperone activities, like its Escherichia coli ortholog DegP. Transgenic plants with reduced levels of Deg1 accumulated normal levels of different subunits of the major photosynthetic protein complexes, but their levels of photosystem‐II (PSII) dimers and supercomplexes were reduced. In vivo pulse‐chase protein labeling experiments showed that the assembly of newly synthesized proteins into PSII dimers and supercomplexes was impaired, although the synthesis rate of chloroplast proteins was unaffected in the transgenic lines. Protein overlay assays provided direct evidence that Deg1 interacts with the PSII reaction center protein D2. These results suggest that Deg1 assists the assembly of the PSII complex, probably through interaction with the PSII reaction center D2 protein. 相似文献
125.
Receptor‐like kinase OsSIK1 improves drought and salt stress tolerance in rice (Oryza sativa) plants
Shou‐Qiang Ouyang Yun‐Feng Liu Peng Liu Gang Lei Si‐Jie He Biao Ma Wan‐Ke Zhang Jin‐Song Zhang Shou‐Yi Chen 《The Plant journal : for cell and molecular biology》2010,62(2):316-329
Receptor‐like kinases (RLKs) play essential roles in plant growth, development and responses to environmental stresses. A putative RLK gene, OsSIK1, with extracellular leucine‐rich repeats was cloned and characterized in rice (Oryza sativa). OsSIK1 exhibits kinase activity in the presence of Mn2+, and the OsSIK1 kinase domain has the ability to autophosphorylate and phosphorylate myelin basic protein (MBP). OsSIK1 promoter‐GUS analysis revealed that OsSIK1 is expressed mainly in the stem and spikelet in rice. The expression of OsSIK1 is mainly induced by salt, drought and H2O2 treatments. Transgenic rice plants with overexpression of OsSIK1 show higher tolerance to salt and drought stresses than control plants. On the contrary, the knock‐out mutants sik1‐1 and sik1‐2, as well as RNA interference (RNAi) plants, are sensitive to drought and salt stresses. The activities of peroxidase, superoxide dismutase and catalase are enhanced significantly in OsSIK1‐overexpressing plants. Also, the accumulation of H2O2 in leaves of OsSIK1‐overexpressing plants is much less than that of the mutants, RNAi plants and control plants, as measured by 3,3′‐diamino benzidine (DAB) staining. We also show that OsSIK1 affects stomatal density in the abaxial and adaxial leaf epidermis of rice. These results indicate that OsSIK1 plays important roles in salt and drought stress tolerance in rice, through the activation of the antioxidative system. 相似文献
126.
Xiao-Hai Feng Fei Chen Hong Xu Bo Wu Jun Yao Han-Jie Ying Ping-Kai Ouyang 《Bioprocess and biosystems engineering》2010,33(9):1077-1085
Propionic acid was produced in a multi-point fibrous-bed (MFB) bioreactor by Propionibacterium freudenreichii CCTCC M207015. The MFB bioreactor, comprising spiral cotton fiber packed in a modified 7.5-l bioreactor, was effective for
cell-immobilized propionic acid production compared with conventional free cell fermentation. Batch fermentations at various
glucose concentrations were investigated in the MFB bioreactor. Based on analysis of the time course of production, a fed-batch
strategy was applied for propionic acid production. The maximum propionic acid concentration was 67.05 g l−1 after 496 h of fermentation, and the proportion of propionic acid to total organic acids was approximately 78.28% (w/w).
The MFB bioreactor exhibited excellent production stability during batch fermentation and the propionic acid productivity
remained high after 78 days of fermentation. 相似文献
127.
128.
The objective was to investigate, using a mouse model, the effects of caffeine on the number of ovulated oocytes, the rate of oocyte maturation, the susceptibility of oocytes to activating stimuli, spindle morphology, and distribution of cortical granules (CGs). Mice were given caffeine (150 mg/kg body weight ip) at various times relative to hCG (-2, 0, and +2h); in an in vitro study, 1, 5 or 10 mM caffeine was added to the maturation culture. Caffeine had no effect on the quality of oocytes in vivo maturation, but caffeine was detrimental to the quality of oocytes matured in vitro. Further studies are needed to determine caffeine concentration in follicles relative to that in culture medium. 相似文献
129.
Wang B Feng WY Wang M Shi JW Zhang F Ouyang H Zhao YL Chai ZF Huang YY Xie YN Wang HF Wang J 《Biological trace element research》2007,118(3):233-243
It has been demonstrated that inhaled fine (d < 2.5 μm) and ultrafine (d < 100 nm) particles produce more severe toxicity than coarse particles. Some recent data support the concept that the central
nervous system (CNS) may be a target for the inhaled fine particulates. This work describes initial observation of the transport
of intranasally instilled fine ferric oxide (Fe2O3) particles in animal brain. The iron micro-distribution and chemical state in the mice olfactory bulb and brain stem on day
14 after intranasal instillation of fine Fe2O3 particle (280 ± 80 nm) suspension at a single dose of 40 mg/kg body weight were analyzed by synchrotron radiation x-ray fluorescence
and x-ray absorption near-edge structure (XANES). The micro-distribution map of iron in the olfactory bulb and brain stem
shows an obvious increase of Fe contents in the olfactory nerve and the trigeminus of brain stem, suggesting that Fe2O3 particles were possibly transported via uptake by sensory nerve endings of the olfactory nerve and trigeminus. The XANES
results indicate that the ratios of Fe (III)/Fe (II) were increased in the olfactory bulb and brain stem. The further histopathological
observation showed that the neuron fatty degeneration occurred in the CA3 area of hippocampus. Such results imply an adverse
impact of inhalation of fine Fe2O3 particles on CNS. 相似文献
130.
Huang JC Lei ZL Shi LH Miao YL Yang JW Ouyang YC Sun QY Chen DY 《Biochemical and biophysical research communications》2007,354(1):77-83
Histone modifications are thought to play important roles in various cellular functions. In this article, the distribution patterns of acetylation on histone H4, methylation on histone H3 lysine 9, and phosphorylation on histone H3 serine 10 were examined in in vivo and in vitro fertilization (IVF) preimplantation mouse embryos by using indirect immunofluorescence and scanning confocal microscopy. We desired to know whether the IVF, which has been widely used as a routine assisted reproductive technology in animal and human, was safe at the epigenetic level. As results, we found that there was no difference in these histone modification patterns in in vivo and IVF mouse embryos from zygote to blastocyst stage. Moreover, these histone modifications had different distributions at all examined stages, but they were consistent with the mouse embryo developmental stages. 相似文献