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1.
Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma radiation [50 grays (Gy) per hour] or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared with radiation-sensitive bacteria and that resistance exhibits a concentration-dependent response to manganous chloride [Mn(II)]. Among the most radiation-resistant bacterial groups reported, Deinococcus, Enterococcus, Lactobacillus, and cyanobacteria accumulate Mn(II). In contrast, Shewanella oneidensis and Pseudomonas putida have high iron but low intracellular manganese concentrations and are very sensitive. We propose that Mn(II) accumulation facilitates recovery from radiation injury.  相似文献   
2.
The marketing of non-timber forest products (NTFPs) through formal channels is a complicated task in the Global South because of the lack of suitable infrastructure and the influence of intermediaries. Strengthening the formal marketing process, on the one hand, can reduce the exploitation of forest products while improving the socioeconomic status of forest fringe villagers. This article examines how identifying the present problems of formal marketing system, can be enhanced in the future in the dry-deciduous forest area of West Bengal, India, where a considerable amount of dispersed Sal (Shorea robusta) forest exists.  相似文献   
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Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines(BRLs) was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under control ed submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.  相似文献   
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The kinetics of meiosis and spermiogenesis in Ascaris lumbricoides in vitro was studied by keeping 12 mature males in nutrient medium. The spermatocytes were made radioactive by supplementing the medium with 3H-thymidine for 2 h, following which they were transferred to fresh medium without 3H-TdR. The nematodes were then killed for preparing histological and squash preparations of the testis. An analysis of the migration of "hot" spermatocytes till the formation of mature spermatozoa, in Kodak AR-10 autoradiograms, suggested that the duration of meiosis and spermiogenesis was a little more than 5.5 and 7.6 days, respectively. The total duration of these two events was about 13.1 days when radioactive spermatozoa were detected for the first time.  相似文献   
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The effect of organic sources of nutrients and inorganic fertilizers, was studied on grain yield of lowland rice and some aspect of soil quality parameters in a field experiment at Agricultural Experimental Farm of Indian Statistical Institute, Giridih, situated at eastern plateau region of India, during consecutive years 1997–2002. Chemical fertilizers and various organic matters were applied to two rice cultivars, Sabita and Subarna. The highest mean grain yield was 3.53 t ha?1 and maximum agronomic efficiency was 60.3 % with the application of inorganic fertilizer followed by cow dung, where 3.47 t ha?1 grain yield was recorded with an agronomic efficiency of 57.5 %. Grain yield of rice recorded under organic sources of nutrients was not significantly different from that of inorganic fertilization though there was improvement in soil quality parameters under organic sources. Soil organic carbon (0.72 %), microbial biomass‐C (279.23 μg g?1 dry soil), urease activity with buffer (33.54 μg urea hydrolyzed g?1 oven‐dry soil) and non‐buffer (21.97 μg urea hydrolyzed g?1 of oven‐dry soil) methods and acid phosphatase activity (2.24 μg para‐nitrophenol released g?1 of oven‐dry soil) analysed following the harvest of the crop were highest under cow dung manure treatment; the most efficient organic source under the experiment. Mean grain yield of rice was significantly higher in Sabita cultivar over Subarna. The regression analyses among the variables have shown that there was linear relationship among soil parameters and grain yield of rice.  相似文献   
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It has been suggested that enhanced anion concentrations at the liquid/vapor interface of airborne saline droplets are important to aerosol reactions in the atmosphere. We report ionic concentrations in the surface of such solutions. Using x-ray photoelectron spectroscopy operating at near ambient pressure, we have measured the composition of the liquid/vapor interface for deliquesced samples of potassium bromide and potassium iodide. In both cases, the surface composition of the saturated solution is enhanced in the halide anion compared with the bulk of the solution. The enhancement of anion concentration is more dramatic for the larger, more polarizable iodide anion. By varying photoelectron kinetic energies, we have obtained depth profiles of the liquid/vapor interface. Our results are in good qualitative agreement with classical molecular dynamics simulations. Quantitative comparison between the experiments and the simulations indicates that the experimental results exhibit more interface enhancement than predicted theoretically.  相似文献   
9.
Importance of melatonin (N-acetyl-5-methoxytryptamine) in the regulation of oocyte maturation has been studied in a carp Catla catla. Melatonin secretory cells were immunocytochemically localized only in the end vesicle. Diurnal and seasonal studies indicated that the serum levels of melatonin exhibit a minimum diurnal value in the mid-day of all seasons, but the peak value is attained either at mid-night or just before the onset of light. Moreover, highest seasonal value of melatonin was noted in the post-spawning phase. Administration of melatonin at different doses (25, 50, or 100 μg/100 g body weight) for 1, 15, or 30 days resulted in either pro- or anti-gonadal effects depending on the reproductive seasons. In vitro study revealed that incubation of oocytes with melatonin 4h prior to addition of MIH in the medium led to an accelerated rate of oocyte maturation through the formation of a complex of two proteins (MPF), cyclin B and cyclin dependant kinase, Cdc2. Moreover, melatonin pre-incubation considerably increased MIH stimulation of histone H1 phosphorylation as compared to MIH alone. Taken together, gathered information promotes the idea of a physiological role of melatonin in the maturation of oocytes in Catla catla.  相似文献   
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This study evaluates employment patterns of domestic migrants and immigrants and also explores the role of ethnic niching for Asian and African American recent arrivals in the context of local structural transformation (e.g., the shift from manufacturing to services). Employment patterns are examined for industry-occupation groups using the 5% Public Use Micro Sample of the 2000 U.S. Decennial Census and the 2006–2010 of the American Community Survey. The study area is a Rustbelt city that has suffered from population loss: the Buffalo-Niagara Falls MSA. Location quotients and shift-share analysis are used to classify employment shifts into four industry-occupation groups: growing, transforming, declining, and emerging. Logistic regressions are estimated to identify the role of various demographic factors and ethnic niches on the employment of recent arrivals in the above four industry-occupation groups. The results show that the employment of recent arrivals vary by migration status and ethnicity. The role of ethnic niches is especially important in declining industry-occupation groups. The analytical framework can be used to understand where and how migrants, both domestic and immigrants, find work. Future studies can focus on the pros and cons of ethnic niching (e.g., barriers to suitable jobs, ethnic entrepreneurship through niche experience) as structural transformation continues across U.S. regions, especially with new technologies.  相似文献   
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