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43.
党廷辉 《中国生态农业学报》2000,8(4):43-46
多年试验研究结果表明,氮(N)磷(P)肥对旱塬冬小麦有显著增产效果,但其随小麦品种、年度波动性很大。N、P肥利用率年际间变化很大,且随其用量的增加而降低。1984~1995年(供试品种"长武-131")N肥利用率变幅为6.4%~58.6%,变异系数为48.7%;P肥利用率变幅为3.7%~19.8%,变异系数为39.5%。1996~1998年(供试品种"长武-134")肥料用量由45kg/hm2增至180kg/hm2,N肥利用率由42.9%降至25.4%(平均36.3%),P肥利用率由10.8%降至3.2%(平均7.2%)。肥料利用率与施肥利润高低并不同步,以肥料利用率作旱塬地区肥料生产效益的度量存在很大局限性,通过分析N与P的连应效应表明,N、P配施是提高其相互利用率的有效途径。 相似文献
44.
Vadim Albertovich Kassianenko Victor Alexandrovich Dragavtsev Genrikh Ivanovich Razorenov Tat'yana Sergeevna Razorenova 《Genetic Resources and Crop Evolution》2003,50(2):157-163
Eighty cotton varieties (Gossypium hirsutum L.) from the collection of VIR (N.I. Vavilov Research Institute of Plant Industry, St. Peterburg, Russia) collection were studied for variability with regard to the duration of their vegetation period. The experiments were carried out in the conditions of the marginal zone of the cotton growing area, that is the city of Krasnodar in the Russian Federation. Thirty-four varieties were studied in 1996–1998, forty-six varieties in 1997–1998. The purpose of this research was to determine the threshold of sensitivity in the varieties of the duration of the period of vegetative growth, which depends upon weather conditions, and to record variations in morphological characters associated with earliness. The data obtained were processed by the method of statusmetry. The mathematical models which were constructed showed the relationship between the criteria for earliness and other morphological and agronomic characters of the plants. 相似文献
45.
Z. Abraham S. K. Malik Gangadhar Eashwar Rao S. Lakshmi Narayanan S. Biju 《Genetic Resources and Crop Evolution》2006,53(2):401-406
A collaborative crop specific exploration and collection mission to collect the germplasm and to study the population size
of male and female/hermaphrodite trees of Malabar tamarind [Garcinia cambogia (Gaertn.) Desr.] in the area of its diversity was undertaken during July 2002 in Kerala and Karnataka. A total of 56 accessions
of Malabar tamarind were collected. Two collections of Malabar tamarind were found to be very specific because of the uncommon
fruit colour, which is pinkish red. All the collected accessions are grown at National Bureau of Plant Genetic Resources (NBPGR)
Regional Station, Thrissur for characterisation and conservation. Extensive range of variability was found in fruit colour,
shape, size and nature of branching and canopy of trees. Characterisation of 13 fruit and five seed characters was done for
51 accessions. The variability was found to be maximum for nipple length (74.8%) and minimum for fruit girth (12.8%). Two
promising accessions were identified based on mean fruit weight (161 g) in IC 354028 and mean rind thickness (15 mm) and mean
rind weight (125 g) in IC 354019. 相似文献
46.
本文利用中国稻瘟病菌生理小种鉴别品种及日本的具已知基因鉴别品种,研究了日本的稻瘟病菌鉴别菌系,我国北方稻区辅助鉴别菌株及保存5~10年菌株的致病性。研究结果表明,菌株的致病性受其自身致病基因及环境因素等多方面影响,在众多的菌株中仍有稳定菌株存在。讨论了稻瘟病菌致病性变异性。提出了稻瘟病菌稳定菌株的筛选方法。 相似文献
47.
Helena Carstensen Lene Larsen Christian Ritz Martin K. Nielsen 《Journal of Equine Veterinary Science》2013
Strongyle parasites are ubiquitous in grazing horses and constitute a potential threat to equine health. Feces were collected from six horses four times daily over a period of 5 days. Fecal egg counts (FECs) were performed to identify any diurnal rhythms in strongyle egg shedding and to quantify variability at the different levels: individual horses, repeated counts, repeated subsamples, different time points, and different days. No significant differences in FECs were found between the different time points (P = .11). The variables—horse, day, subsample, and egg count—accounted for a variance of 104.83, 0.10, 7.24, and 5.61, respectively. The apparent lack of additional variability between the four different time points suggests that time of the day chosen for collecting fecal samples does not constitute a source of error in field studies. The majority of variability exists between different subsamples and repeated egg counts on the same subsamples, whereas the variability of FECs between following days can be considered negligible. The findings of this study have implication for designing and performing field surveillance of strongyle FEC levels and applying the FEC reduction test for evaluating anthelmintic efficacy. 相似文献
48.
Relationships between line per se and testcross performance for agronomic traits in two broad-based populations of maize 总被引:1,自引:0,他引:1
Degree of the association between line per se performance (LP) and testcross performance (TP) is important in breeding programs
and simultaneous improvement of commercial hybrids and their parental lines. This experiment was designed to study genetic
variability and genetic correlation for several agronomic traits in two maize (Zea mays L.) broad-based populations (NS12-SG and NS14-SG). Independent trials with 80 entries of S1 progenies as well as their testcrosses were arranged according to an incomplete block design with replicates in sets. Grain
yield, stay green, anthesis-silking interval, stalk water content and grain moisture were evaluated in four environments.
The anthesis-silking interval had the highest genetic variation, followed by stay green. High heritability estimates (>0.50)
for all traits, pointed out that further selection would be possible. Genetic correlations between line per se and testcross
performance were lowest for grain yield (0.396** and 0.592**, for NS12-SG and NS14-SG, respectively), and highest for grain
moisture (0.937** and 0.821**, respectively). High correlations between line per se and their testcrosses for stay green,
anthesis-silking interval, stalk water content and grain moisture indicated that additive gene action might be more important
than dominance in controlling the expression of these traits. 相似文献
49.
Pedro Revilla Pablo Velasco Rosa Ana Malvar María Elena Cartea Amando Ordás 《Genetic Resources and Crop Evolution》2006,53(4):771-777
Genotypes conserved in active collections may suffer genetic erosion and modifications. The objective of this work was to
investigate changes in germination and vigour in maize (Zea mays L.) inbred lines during cold storage in an active collection. Seeds of 16 maize inbreds produced along 16 years were evaluated
for emergence and seedling vigour in a growth chamber. Linear and quadratic regressions of vigour and viability-related traits
over seed age were calculated and tested for homogeneity. The seed of five production years of five inbreds that behaved differently
in the regression analysis was multiplied in 1998, and original and renewed seed were evaluated in a growth chamber in 1999.
Viability and vigour decreased linearly with age for most inbreds, particularly for B84 and EP10, varied at random for a few
inbreds, and remained high for EP56 and A295. Aging caused reduction of vigour and loss of viability in most inbreds. There
was variability for seed longevity among inbred lines; longevity was highest for inbred EP56. During storage, some seeds of
each inbred died, while enduring seeds, when multiplied, produced new seed with enhanced viability and vigour compared to
the average seed of the inbred, suggesting natural selection for viability and vigour during storage within inbred lines. 相似文献
50.