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51.
Two new freshwater species of the small family Capilloventridae are recorded from rivers in south-eastern Australia. Capilloventer acheronensis sp. n. has all hair setae anteriorly and dissimilar crotchet setae without hairs posteriorly while Capilloventer longicapitus sp. n. has an elongate prostomium, very long hair setae anteriorly and all bifid setae posteriorly. Immature specimens from south-west Western Australia appear to represent a further species and are tentatively included within the family. Additional specimens of Capilloventer australis Erséus, 1993 have allowed some features (setae, segmental glands, genitalia and ventral buccal organ) to be described in more detail. The new C. australis specimens are from the upper reaches of Victorian rivers, showing that it is a freshwater species, rather than a marine incursion as the estuarine type locality suggested. There are now more freshwater species than marine species, although the origin and phylogenetic relationships of the family remain unclear.  相似文献   
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A method of analysis of growth patterns in two dimensions haspreviously been proposed by Richarads and Kavanagh (1943),whichconsists of evaluating the divergence of velocity by vectoranalysis. The method has been adpted for solution by numericalmethods, and has been programmed for an electronic computer.The method and the programme are described, and applied to theanalysis of leaf growth in Xanthium. These preliminary resultssuggest that the system could be successfully applied to a widevariety of problem of 2-dimensional growth.  相似文献   
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Abstract. The effects of pheromone concentration and ambient temperature on male gypsy moth, Lymantria dispar (L.) (Lepidoptera), flight responses to pheromone were investigated in a wind tunnel. As the pheromone dose increased from 10 ng to 1000 ng, males flew at progressively slower airspeeds and ground speeds, and reduced their wingbeat frequencies. Furthermore, the moths steered significantly smaller course angles as the pheromone concentration increased, indicating that they were adopting a more upwind heading. The overall width of the flight tracks also decreased when males flew in more concentrated pheromone plumes. Estimation of plume dimensions using a male wing-fanning assay showed that as pheromone dosage increased, the resultant active spaces became wider, indicating that an inverse relationship existed between the dimensions of the time-averaged plume and the width of track reversals and that most turns were initiated within the plume. When males were flown at cool (20°C) and warm (26°C) ambient temperatures but to equivalent pheromone emission rates, they exhibited higher airspeeds and ground speeds at the higher temperature but steered larger course angles. Track widths, and length of track legs were, however, similar at the two temperatures. The mean turning frequency was nearly the same (c. 4 turns/s) across all the concentrations and temperatures tested even though the moths' thoracic temperature differed by 5°C when the ambient temperature was varied.  相似文献   
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Methanol Accumulation in Maturing Seeds   总被引:4,自引:2,他引:4  
During in vitro growth and maturation of soybean seeds, cessationof embryo growth and dry weight accumulation occurred in thepresence of abundant C and N nutrients. Axis followed by cotyledontissues changed from green to yellow, and post-harvest germinationpotential declined if cultured after yellowing of axis tissues.A tissue specific accumulat;on of methanol occurred during thein vitro culture of immature seeds (i.e. initially 50 to 70mg fresh weight) to maturity in liquid medium. Methanol accumulatedto 3.0 g m–3 or 50 µg seed–1 in the medium,while methanol decreased from 37 to about 3.0 µg g–1fresh weight in cotyledons. By contrast, axis tissues increased20-fold in methanol concentration to 90 µg g–1 during20 d in culture. Ethanol was present only in trace amounts inaxis tissues and medium. Addition of exogenous methanol vapourto in situ grown seeds during precocious maturation decreasedsubsequent seedling vigour and germination with increasing levelsof exposure. Methanol accumulation in axis tissues during thegermination phase was not correlated with high temperature andtissue water content treatments which simulated pre-harvestdeterioration of seeds. However, the accumulation of methanolduring in vitro seed development and maturation in liquid culturemay contribute to reduced post-harvest germination performance. Key words: Soybean, Glycine max, seed maturation, in vitro, methanol  相似文献   
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The presence and distribution of two groups of enzymes has been determined histochemically on sections of the schistosome-bearing snail Australorbis glabratus. By the use of specific inhibitors, attempts have been made to characterize further the enzymes occurring in the various organs and tissues.
As a result of this study it has been found that alkaline and acid phosphatase are widely distributed but have identical localizations only in the kidney and albumen gland. Both enzymes react typically to the action of the usual inhibitors.
Among the non-specific esterases. an enzyme corresponding to the mammalian A-type esterase (aromesterase) is present in the brain; while a B-type esterase (aliesterase) is located in the digestive gland, intestine, and on the glandular region of the foot surface.
A true lipase (an esterase acting on an undissolved substrate) is found principally in the albumen gland, with an indication of its presence in the digestive gland and in portions of the digestive tract.
An enzyme with the properties of an acetylcholinesterase occurs in the radula sac, oesophagus, preputium, junction of carrefour and oviduct, and amoebocytes. A positive reaction for cholinesterase is also obtained with frozen sections of brain but, although this enzyme has been shown biochemically to hydrolyse acetylcholine and is inhibited by low concentrations of eserine. it is remarkably resistant to the action of organophosphorous compounds, and its true nature cannot he stated with certainty.  相似文献   
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1. Regulation of rivers for human demands has led to extensive forest dieback on many floodplains. If these important ecosystems are to be maintained under future drier climates, we need accurate tools for predicting forest dieback. In the absence of spatially explicit flooding histories for many floodplains, changes in groundwater conditions may be a good indicator of water availability and, therefore, an important environmental indicator. 2. Eucalyptus camaldulensis forests of Australia are an acute example of forest dieback, with 70% of the Victorian Murray River floodplain dying back. We quantified the relationship between forest dieback and ground water across this extensive floodplain (c. 100 000 ha of forest over 1500 km of river length). 3. A combination of extensive ground surveys, remotely sensed data and modelling methods was used to predict forest dieback at the time of the survey and in the past. This approach provides a valuable tool for accurately monitoring forest condition over large spatial scales. Forest dieback was estimated to have increased from 45 to 70% of the floodplain between 1990 and 2006. 4. Accurate groundwater data (depth and salinity) over a 20‐year period were obtained for 289 bores and summarised using nonlinear regression. Groundwater depth and salinity were strong predictors of stand condition. This suggests that changes in groundwater conditions could be used to signal areas vulnerable to forest dieback and prioritise the limited water available for managed flooding. 5. In the upper Murray, where ground water is predominantly fresh (<15 mS cm?2), dieback increased with increasing groundwater depth. In contrast, the condition of stands in the lower Murray improved with increases in groundwater depth due its high salinity (>30 mS cm?2). These regional differences in response of the same tree species to groundwater conditions show that our understanding of the drivers of forest dieback is best achieved at spatial and temporal scales representative of the problem.  相似文献   
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