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371.
The use of genetic,manual and chemical methods to control pollination in vegetable hybrid seed production: a review
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Production of hybrid varieties of vegetable crops is currently a desired breeding goal, due to their remarkable agronomic performance and to the possibility of intellectual property protection. However, efficient hybrid production requires a careful pollination control to guarantee the hybrid nature of F1 seed. Several technologies ranging from manual emasculation to genetic transformation are used to inhibit pollen production in mother plants. In this review, we examine the principles underlying strategies like genetically determined systems (genic male sterility, cytoplasmic–genic male sterility, self‐incompatibility) and other methods (manual emasculation, chemical‐hybridizing agents) in different species, considering the benefits and drawbacks of their adoption. Finally, we present the current state of the art for vegetable hybrid seed production. 相似文献
372.
Soil carbon cycling is an essential component of agroecosystems models. Simulating soil carbon (Cs) cycling has become an issue of societal importance for Cs storage can play a role reducing the rate of increase of atmospheric CO2 concentration. To participate in carbon trading markets, growers have to evaluate their local, site-specific options to increase Cs or reduce Cs losses. This paper introduces C-Farm, a daily time step cropping systems model that allows calculating the Cs balance using a one-pool soil organic matter sub-module. In C-Farm the Cs turnover rate depends non-linearly on Cs and on environmental and management controls. Two long-term experiments were selected to evaluate C-Farm: a wheat-summer fallow 70+ years experiment at Pendleton, Oregon, and the continuous wheat experiment at the Rothamsted experiment station in the United Kingdom. C-Farm simulated well the long-term Cs evolution observed in these experiments. In addition, simulations performed in the dryland US Pacific Northwest show its applicability for assessing Cs storage rates in a region with large variation in precipitation. C-Farm can be easily customized to a large array of local conditions, providing robust estimates of short- and long-term on-farm carbon storage rates. The model is being further developed to provide estimates of nitrous oxide emission. 相似文献
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Marcia R. S. Konopatzki Lúcia H. P. Nóbrega Claudio L. Bazzi Davi M. Rocha 《Journal of plant nutrition》2016,39(3):323-336
For fruiting trees, fertilization is usually recommended based on the analyses of soil and leaves, adopting a standard value for the whole orchard. This management can lead to undesirable imbalances to the plants and local agroecosystem. Thus, this trial aimed at mapping the spatial variability of properties of soil, plant and yield in a commercial area of pears production and investigating the yield response to a distinguished fertilization. The trial was carried out in Nova Laranjeiras, Paraná, where 36 trees were selected to receive conventional fertilization (CF) and other 36 trees received a site-specific fertilization (SSF). All variables (chemical and physical attributes of soil, leaf tissue, and yield) showed some spatial dependence. For all years, yield variability was considered very high. The yield of SSF system was slightly higher (2,625 kg ha?1) and took up a larger area (59%) when compared to SF system (2,548 kg ha?1 at 41% area). 相似文献
377.
BACKGROUND: Flumioxazin is a soil-applied herbicide recommended for broadleaf weed control in soybeans and peanuts, and was recently introduced for vineyard weed management. Considering the limited information available in relation to flumioxazin field soil behaviour, the main objectives of this study were to determine the persistence, adsorption and movement of flumioxazin in soil in four Chilean vineyard production areas. RESULTS: DT(50) values ranged from 10.6 +/- 1.0 to 32.1 +/- 3.1 days between localities, being correlated with rain events, time between herbicide application and first heavy rain event, and soil pH. Flumioxazin soil residue found at 90 days after application (DAA) varied from 9.6 to 24.9% of the initial amount applied, and depended on the total rainfall amount that occurred during the first 90 DAA. Herbicide leaching below 15 cm was approximately 45% of the flumioxazin detected at 90 DAA in the whole soil profile. Flumioxazin maximum leaching soil depth was 45 cm at all locations. K(d) values varied from 2.54 to 6.51 mg L(-1), depending on localities and soil profile depth, and correlated positively with organic carbon and clay content. CONCLUSIONS: These results indicate that flumioxazin is a herbicide with low environmental risk owing to its short DT(50), reduced soil residues 3 months after application and low effective dose. 相似文献
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Marina Marrari Sergio R. Signorini Charles R. McClain Marcelo Pájaro Patricia Martos María Delia Viñas Jorge Hansen Roxana Dimauro Georgina Cepeda Claudio Buratti 《Fisheries Oceanography》2013,22(3):247-261
The mid‐shelf front (MSF) of the Buenos Aires province continental shelf in the Southwestern Atlantic Ocean plays a central role in the pelagic ecosystem of the region acting as the main spring reproductive area for the northern population of the Argentine anchovy Engraulis anchoita and supporting high concentrations of chlorophyll as well as zooplankton, the main food of anchovy. To investigate the influence of environmental variability on the reproductive success of E. anchoita, we analyzed a 13‐yr time series (1997–2009) of environmental data at MSF including chlorophyll dynamics, as well as zooplankton composition and abundance, ichthyoplankton distributions, and recruitment of E. anchoita. Spring chlorophyll concentrations showed high interannual variability and were mainly influenced by changes in water temperature and vertical stratification, which in turn control nutrient supply to the surface. Chlorophyll dynamics (magnitude, timing, and duration of the spring bloom) explained most of the variability observed in E. anchoita recruitment, most likely via fluctuations in the availability of adequate food for the larvae. Our results suggest that satellite ocean color products can be valuable tools for understanding variability in ecosystem dynamics and its effects on the recruitment of fish. 相似文献
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Álvarez‐Ruiz Píndaro Mejía‐Ruiz Claudio Humberto Magallón‐Barajas Francisco Javier Escobedo‐Bonilla César Marcial 《Aquaculture Research》2013,44(5):772-782
White spot syndrome virus (WSSV) is a major threat for farmed shrimp worldwide. RNA interference (RNAi) is the most recent tool against viral diseases. Rab7 silencing effectively inhibited virus infections in juvenile shrimp, but the antiviral effect in brooders remains unknown. This study found a homologue Penaeus monodon Rab7 gene in Litopenaeus vannamei brooders from Mexico. Sequence identity was >99% to a Thai LvRab7 sequence and >94% to Rab7 sequences from P. monodon or Marsupenaeus japonicus. Animals treated with a partial (494 bp) or a complete (618 bp) LvRab7 dsRNA sequences and challenged 48 h post treatment (hpt) with a high WSSV dose showed 80–88% mortality respectively. Shrimp treated with 4 or 20 μg LvRab7 dsRNA and challenged with a WSSV high dose had 80% mortality each, but it was reduced to 33% and 40%, respectively, with a low dose. Efficacy of dsRNA to reduce shrimp mortality was dependent on virus dose used regardless of dsRNA concentration. A significant reduction in LvRab7 mRNA levels was observed at 120 hpt. In conclusion, silencing LvRab7 in brooders showed a mild antiviral effect against a WSSV challenge at 48 hpt. 相似文献