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Mixed tree cropping systems have been proposed for sustainable nutrient management in the humid tropics. Yet, the nutrient interactions between intercropped trees have not been addressed sufficiently. In the present study we compare the temporal and spatial patterns of the uptake of applied 15N by four different tree crops in a mixed tree cropping system on a Xanthic Ferralsol in central Amazônia, Brazil, during one year. Most of the N uptake occurred during the first two weeks. Very little N was recovered by peach palm (Bactris gasipaes), more by cupuassu (Theobroma grandiflorum) and annatto (Bixa orellana) and most by Brazil nut (Bertholletia excelsa). Due to tree pruning the total accumulation of applied 15N in the above-ground biomass of annatto decreased throughout the year. It remained constant in cupuassu and peach palm and increased in Brazil nut. Brazil nut showed an extensive root activity and took up more fertilizer N applied to neighboring trees than from the one applied under its own canopy in contrast to the other three tree crops. Therefore, trees with wide-spread root systems may not need to receive N fertilizer directly but can take up N applied to other trees in the mixed cropping system. This means that such trees may effectively decrease N leaching when intercropped with trees that have dormant periods or places with low N uptake, but also exert considerable resource competition.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   
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In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis (crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative, as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.
Sabine AugustinEmail:
  相似文献   
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Morinda citrifolia (noni) is known to contain genotoxic anthraquinones in the roots. Because of the widespread use of noni juice, the possible genotoxic risk was examined through a battery of short-term tests. Noni juice was also chemically analyzed for the possible presence of anthraquinones. Noni juice extract in the Salmonella microsome assay showed a slight mutagenic effect in strain TA1537, due to the presence of flavonoids. No mutagenicity was observed in the mammalian mutagenicity test with V79 Chinese hamster fibroblasts. Rats treated with a noni juice concentrate did not show DNA repair synthesis (UDS) in primary rat hepatocytes, nor could DNA adducts or DNA strand breaks be observed. HPLC analysis of noni juice for anthraquinones was negative, with a sensitivity of <1 ppm. In summary, chemical analysis and genotoxicity tests reveal that noni juice does not have a genotoxic potential and that genotoxic anthraquinones do not exist in noni juice.  相似文献   
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The effect of oxygen on the levels of glutathione, an important antioxidant, in must and wine was studied using a novel LC-MSMS method for the analysis of reduced and oxidized glutathione. This study found that the storage of grape juice at high SO2 and ascorbic acid levels at -20 degrees C did not lead to a decrease in reduced glutathione levels. The effect of varying the oxygen levels in South African white grape juices, which included a reductive treatment (less than 0.3 mg/L dissolved O2 added), a control treatment (between 1.0 and 1.5 mg/L dissolved O2 added), and an oxidative treatment (3.5-4 mg/ L dissolved O2 added, without SO2) on reduced glutathione levels in the juice and resulting wine was also investigated. A custom build press was used to press whole bunches of two different Sauvignon Blanc and Colombard grapes. Alcoholic fermentation and oxygen additions to the must led to lower reduced glutathione levels in the wine. Reduced glutathione levels were only significantly higher in the wine made from reductive juice that had the highest initial reduced glutathione levels in the grapes.  相似文献   
16.
OBJECTIVE: To evaluate the effect of a primary school-based intervention providing free fruit and vegetables (F&V), separately for children of Dutch and of non-Western ethnicity. SETTING: Primary schools in two regions (west and east) in The Netherlands. DESIGN AND METHODS: Participating schoolchildren and their parents completed questionnaires at baseline and 1 year later, including questions on usual F&V intake, potential determinants and general demographics. Primary outcomes were the usual fruit intake and the usual vegetable intake as assessed by parent- and child self-reported food frequency measures. Secondary outcome measures were child- or parent-reported taste preference, knowledge of daily recommendations, availability, and accessibility for fruit intake. Multilevel regression analyses were used to assess differences at follow-up adjusted for baseline values between the control and intervention group using both child and parent reports. SUBJECTS: Five hundred and sixty-five children of Dutch ethnicity and 388 children of non-Western ethnicity (mean age 9.9 years at baseline) and their parents. RESULTS: Children of non-Western ethnicity in the intervention group reported a significantly higher vegetable intake (difference = 20.7 g day-1, 95% confidence interval (CI) = 7.6-33.7). A significant positive intervention effect was also found for fruit intake for children of Dutch ethnicity (difference = 0.23 pieces day-1, 95% CI = 0.07-0.39). No significant effects in intake were observed based on parent reports. Significant positive intervention effects were also found for perceived accessibility among children of non-Western ethnicity, as well as for parent-reported taste preference of their child among children of non-Western ethnicity and boys of Dutch ethnicity.CONCLUSION: Providing children with free F&V had some positive effects on child-reported intakes and important correlates of intakes.  相似文献   
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Journal of Pest Science - Longhorn beetles are commonly moved among continents within wood packaging materials used in trades. Visual inspections carried out at points of entry often fail to detect...  相似文献   
19.
Copepods have proven to be an ideal source of live food for the production of marine fish larvae in aquaculture. Therefore, there is a need to develop new methods for production and storage of copepod eggs that can be hatched and used at fish farms. In the present study quiescent eggs of Acartia tonsa were stored for periods up to 35 weeks at different temperatures, salinities and oxygen conditions in a full factorial experiment. None of these storage conditions seemed to induce diapause in eggs even though this has been reported by other authors. The most promising storage conditions were those involving low temperature (<5°C), medium salinity (10–20 ppt) and anoxia. The practical aspects of these results for aquaculture are discussed.  相似文献   
20.
One year old golden ide (Leuciscus idus melanotus) were starved for 2 weeks at 20°C (time zero) and then they were fed either freeze-dried mosquito larvae (natural diet) or a commercial fish chow (artificial diet) at an ambient temperature of 14°C and 20°C, respectively. Growth parameters and biochemical data in the liver were measured at time zero and after 3 and 7 weeks of specific regimen. If compared to natural food, the artificial diet caused transient increase in anabolic activity of the liver, but prevented long-lasting hepatocyte proliferation (increase of total liver DNA). After 3 weeks on artificial diet, the body weight was significantly higher and the liver mass doubled compared to ide kept on the natural regimen; tissue DNA content indicated that the hepatocyte volume increased mainly by increased protein content and corresponding uptake of water; lipid and glycogen contents were increased by a factor of 3–6, and the RNADNA ratio was increased accordingly. The growth of the ide, as reflected by the condition factor and hepatosomatic index (HSI), was virtually stopped when the artificial regimen was maintained for 7 weeks, whereas on natural food the condition factor was increased and liver weight and DNA were doubled. Growth of the fish maintained at 14°C was significantly lower than that of fish maintained at 20°C, though the total liver DNA was still increased on the natural regimen during the experiment. Less lipid was stored by fish maintained at 14°C, whereas protein and glycogen deposits were enlarged, if compared to fish maintained at 20°C. The specific activity of cytochrome oxidase in liver mitochondria and of NADPH cytochrome c reductase in the microsomal fraction were found independent of diet and ambient temperature. Oxidative capacity of hepatocytes (mitochondrial protein/mg DNA) remained unchanged, and microsomal protein/cell appeared reduced in response to the artificial food. However, reduction of cell number on this diet resulted in less total mitochondrial and microsomal protein in the organ. Golden ide liver is found to be a sensitive experimental model to characterize the mutual influence of diet and temperature on fish; the results are discussed with regard to the usage of golden ide as test fish for water pollution.  相似文献   
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