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101.
Kourosh Mohammadi Mohammad Taghi Beigi Nassiri Enayat Rahmatnejad Masoud Sheikh Jamal Fayazi Amin Karimi Manesh 《Tropical animal health and production》2013,45(2):671-677
This study reports on the phenotypic and genetic (co)variance components for reproductive traits in Zandi sheep, using between 1,859 and 2,588 records obtained from 577 ewes. The data were collected from the Khojir Breeding Station of Zandi sheep in Tehran, Iran from 1994 to 2008. The basic traits were litter size at birth (LSB), litter size at weaning (LSW), litter mean weight per lamb born (LMWLB), and litter mean weight per lamb weaned (LMWLW), and the composite traits were total litter weight at birth (TLWB) and total litter weight at weaning (TLWW). Genetic analyses were carried out using the restricted maximum likelihood method that was explored by fitting the additive direct genetic effects and permanent environmental effects of the ewes as random effects and the ewe age at lambing and lambing year as fixed effects for all of the investigated traits. Akaike’s information criterion was used to choose the most appropriate model. LSB, LSW, LMWLB, LMWLW, TLWB, and TLWW direct heritability estimates were 0.07, 0.05, 0.12, 0.10, 0.08, and 0.14, respectively. The estimated fractions of variance due to the permanent environmental effects of the ewe ranged from 0.03 for LMWLB to 0.08 for LMWLW and TLWW. Corresponding repeatability estimates ranged from 0.10 for LSW to 0.22 for TLWW. Direct genetic correlations varied from ?0.61 for LSB–LMWLB to 0.88 for LSB–LSW and LSB–TLWB. Results indicate that genetic change depends not only on the heritability of traits, but also on the observed phenotypic variation; therefore, improvement of non-genetic factors should be included in the breeding programs. 相似文献
102.
Mohammad Amin Jalali Thomas Van Leeuwen Luc Tirry Patrick De Clercq 《Phytoparasitica》2009,37(4):323-326
The toxicity of pirimicarb, imidacloprid, dimethoate, lambda-cyhalothrin, flonicamid and spinosad to the two-spot ladybird,
Adalia bipunctata, was evaluated in a laboratory study. Susceptibility of fourth instars and female adults was assessed by measuring toxicity
via residual contact and ingestion through feeding on contaminated green peach aphids (Myzus persicae). Flonicamid and spinosad had no lethal effects on larvae and female adults. Pirimicarb was harmless to the predator by ingestion
exposure but showed some residual toxicity at high concentrations to both larval and adult stages. Imidacloprid was highly
toxic to the larval stage by residual and ingestion exposure but caused very low adult mortality when ingested through contaminated
prey. Dimethoate and lambda-cyhalothrin were highly toxic to both the larval and adult stages of the ladybird. Our findings
indicate that pest management programs in agricultural crops using dimethoate, lambda-cyhalothrin and, to a lesser degree,
imidacloprid, are detrimental to A. bipunctata, whereas pirimicarb, flonicamid and spinosad are more compatible with the use of this predator. 相似文献
103.
104.
A set of 105 European wheat cultivars was assessed for seedling resistance and adult plant resistance (APR) to stripe (yellow)
rust in greenhouse and field tests with selected Australian isolates of Puccinia striiformis f. sp. tritici (Pst). Twelve cultivars were susceptible to all pathotypes, and among the remainder, 11 designated seedling genes (Yr1, Yr3, Yr4, Yr6, Yr7, Yr9, Yr17, Yr27, Yr32, YrHVII and YrSP) and a range of unidentified seedling resistances were detected either singly or in combination. The identity of seedling
resistance in 43 cultivars could not be determined with the available Pst pathotypes, and it is considered possible that at least some of these may carry uncharacterised seedling resistance genes.
The gene Yr9 occurred with the highest frequency, present in 19 cultivars (18%), followed by Yr17, present in 10 cultivars (10%). Twenty four cultivars lacked seedling resistance that was effective against the pathotype
used in field nurseries, and all but two of these displayed very high levels of APR. While the genetic identity of this APR
is currently unknown, it is potentially a very useful source of resistance to Pst. Genetic studies are now needed to characterise this resistance to expedite its use in efforts to breed for resistance to
stripe rust.
Colin R. Wellings seconded from NSW Department of Primary Industries. 相似文献
105.
Yeong Sheng Tey Mark Brindal Elton Li Gurjeet Gill Johan Bruwer Amin Mahir Abdullah 《Journal Of Agricultural & Food Information》2018,19(2):162-175
Information is key in reducing the uncertainties of sustainable agricultural practices (SAPs). The objective of this study was to improve the understanding of the relationship between utilized informational sources and other key identified factors affecting Malaysian vegetable producers' choices. The findings of a multivariate probit model suggest that information sources are complementary. The choices for these sources are influenced by heterogeneity in access to credit, social network (member of farmers association), and farm settings (distance from farm to market, resource depletion issues, and geographical regions). Future promotion of SAPs should be delivered through the provision of quality content disseminated through the preferred information sources, which target potential users. 相似文献
106.
Mahdi Najafi-Ghiri Abbas Mirsoleimani Hossein Amin 《Arid Land Research and Management》2017,31(4):431-445
Nutrient deficiency may be a reason for citrus decline in many countries. In the current investigation, soil and leaf samples of 63 Washington Navel orange orchards in arid lands of southern Iran (Darab region) were analyzed to study the nutritional status of orange orchards and to find relationships between soil properties and nutrients content of soils and orange leaves. The soils differed widely in clay content (3–37%), pH value (7.04–7.95), calcium carbonate equivalent (18–86%), and organic matter content (0.3–12%). These soils represented a wide range of plant nutrients concentration. Majority of the studied soils had sufficient concentrations of all nutrients (except Fe). Results indicated that pH, organic matter, clay, and calcium carbonate contents are the most important characteristics that control the soil nutrients availability. The mean contents of N, K, P, Fe, Mn, Zn, and Cu in leaves were 2.59, 0.84, and 0.14% and 66, 44, 17, and 12?mg?kg?1, respectively. Most orchards showed K, Fe, and Zn deficiencies. We found no relationships between nutrients content in leaf and soil (except for K, Mn, and Zn); and this indicated that soil analysis may not be a reliable method for most nutrient deficiency diagnosis. 相似文献
107.
Tropical acid soils are highly weathered as they exist under tropical environment with high rainfall and temperature throughout the year, which affects nitrogen availability. Soil organic nitrogen is important in estimating soil nitrogen availability. The combined use of urea and compost in this study was carried out to decrease sole dependence on urea, buffer soil acidification, and reduce nitrogen losses through leaching. Thus, soil buffering capacity, incubation, and organic nitrogen fractionation studies were conducted to determine soil buffering capacity, availability of total nitrogen, organic fractions nitrogen, and inorganic nitrogen in soil after 90 days of incubation following compost. Soil pH, buffering capacity, total nitrogen, organic nitrogen fractions, exchangeable ammonium, and available nitrate were higher in all treatments with compost and combined use of urea and compost. Total hydrolyzable nitrogen, ammonium-nitrogen, (ammonium + amino sugar)-nitrogen, amino sugar-nitrogen, and amino acid-nitrogen were higher in soils with urea and compost suggesting that decomposition of soil organic fractions nitrogen into inorganic nitrogen (ammonium and available nitrate was affected by the addition of urea and compost. Urea can be amended with compost to regulate availability nitrogen in soil for crop use. 相似文献
108.
Perumal Palanivell Nik Muhamad Ab Majid 《Communications in Soil Science and Plant Analysis》2017,48(17):2083-2092
Application of urea in lowland rice fields leads to ammonia (NH3) volatilization and environmental pollution, and diminishes nitrogen recovery by rice (Oryza sativa L.). Amending urea with biochar could reduce NH3 loss from urea as well as improve chemical properties of acid soils. An incubation study was conducted using a closed-dynamic air flow system to determine NH3 volatilization from urea and chemical properties of an acid soil (Typic Paleudults). The soil was mixed with three rates of chicken litter biochar (20, 40, and 60 g pot?1) and 1.31 g urea. Mixing an acid soil with biochar (60 g pot?1) in waterlogged to stimulate conditions in paddy condition significantly reduced NH3 loss and total titratable acidity. Biochar application also increased soil pH, total nitrogen, available nitrate, organic matter, total organic carbon, total carbon, available phosphorus, and exchangeable cations. Thus, chicken litter biochar can be used to reduce urea-N loss and ameliorate chemical properties of acid soils. This aspect is being embarked on in our on-going field experiments. 相似文献
109.
To avoid environmental pollution due to excessive use of inorganic fertilizers, it is essential to increase the availability of nutrients using environmentally friendly resources, such as composts and clinoptilolite zeolite, in soil fertility management. In this study, an attempt was made to use different rates of inorganic fertilizers, compost, and clinoptilolite zeolite to correct the ongoing excessive use of inorganic fertilizers. A pot study using maize (Zea mays L.) as a test crop was carried out to determine the effects of amending inorganic fertilizers with compost and clinoptilolite zeolite on: (i) selected soil chemical properties, and (ii) N, P, and K uptake and use efficiency in maize cultivation. The pot study was conducted for 45 days (tasseling stage of maize). Amending inorganic fertilizers with compost and clinoptilolite zeolite increased soil total N, exchangeable Ca, Mg, K, and available P. Furthermore, P and K uptake and use efficiency of maize were significantly improved upon amending inorganic fertilizers with compost and clinoptilolite zeolite. Soil chemical properties and productivity of maize on acid soils can be improved through co-application of compost and clinoptilolite zeolite. However, field application of the authors’ findings is being evaluated in an on-going field experiment. 相似文献
110.
Satoru Okubo Parikesit Koji Harashina Dendi Muhamad Oekan S. Abdoellah Kazuhiko Takeuchi 《Agroforestry Systems》2010,80(1):17-31
Agroforestry systems have been re-evaluated with a renewed scientific interest as appropriate models for achieving sustainable
production while maintaining planned and associated biodiversity and agroecosystem functioning. Traditional bamboo-tree gardens
in West Java are known to play substantial ecological and socioeconomic roles. In this study, we attempted to elucidate the
relationship between income generation and biodiversity by studying 83 bamboo-tree gardens that varied in species composition
and degree of commercialization. We conducted a survey of the vegetation and interviewed the owners or managers of each plot.
We identified 42 planned and utilized species and 19 associated non-use species. Eight vegetation groups were identified by
two-way indicator species analysis (TWINSPAN), each of which varied in individual densities of different utilization species
types, Simpson’s diversity index, management intensities, and potential annual gross income. The group with the highest potential
income generation was dominated by clove trees (Syzygium aromaticum); however, this group also had a lower level of diversity and higher levels of management intensity than the other groups,
but all of the pairwise groups were not significantly different. About 60% of the villagers used at least some fuelwood as
a domestic energy source, and almost all of them collected fuelwood from bamboo-tree gardens regardless of ownership. There
were no significant differences in density of potential fuelwood species among the vegetation groups. There were significant
positive correlations between income and most management activities. The regression model between gross income and Simpson’s
diversity index with the best fit was a unimodal curve, which strongly suggests that maximum diversity can be conserved at
an intermediate level of income. Nevertheless, this intermediate level of gross income is probably not adequate as the primary
source of income for garden owners, although some gardens had the potential to achieve higher income levels with no decline
in diversity. We suggest that maximizing individual density and multistratifying canopy layers could improve profitability
within perennial crop-based agroforestry systems in West Java. 相似文献