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71.
Municipal annexation is the most common form of local government boundary change and can have profound impacts on the annexing municipality as well as the area being annexed. While urban scholars have often touted the economic benefits of annexation for municipalities, little research has been conducted on the effect of annexation type on the economic well‐being of a municipality. Do voluntary annexations result in a larger economic windfall for annexing municipalities? Do involuntary annexations cost more? This study examined more than 6,000 annexations conducted by North Carolina municipalities between 1990 and 2000 in order to explore the impact annexation methodology had on municipal fiscal health. The results reveal that during the study period annexation resulted in a decrease in municipal fiscal health for North Carolina municipalities and that involuntary annexation had a particularly detrimental effect. This finding contradicts much of the previous research on the economic benefits of annexation for municipalities. 相似文献
72.
Molecular mapping and characterization of traits controlling fiber quality in cotton 总被引:34,自引:1,他引:34
Cotton (Gossypium spp) is the world's leading natural fiber crop. Genetic manipulation continues to play a key role in the improvement of fiber
quality properties. By use of DNA-based molecular markers and a polymorphic mapping population derived from an inter specific
cross between TM-1 (G. hirsutum) and 3-79 (G. barbadense), thirteen quantitative trait loci (QTLs) controlling fiber quality properties were identified in 3-79, an extra long staple
(ELS) cotton. Four QTLs influenced bundle fiber strength, three influenced fiber length, and six influenced fiber fineness.
These QTLs were located on different chromosomes or linkage groups and collectively explained 30% to 60%of the total phenotypic
variance for each fiber quality property in the F2 population. The effects and modes of action for the individual QTLs were characterized with 3-79 alleles in TM-1 genetic
background. The results indicated more recessive than dominant, with much less additive effect in the gene mode. Transgressive
segregation was observed for fiber fineness that could be beneficial to improvement of this trait. Molecular markers linked
to fiber quality QTLs would be most effective in marker-assisted selection (MAS) of these recessive alleles in cotton breeding
programs.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
73.
Russell S. Crosbie Brett Wilson Justin D. Hughes Christopher McCulloch Warren McG. King 《Agricultural Water Management》2008,95(3):211-223
Planting trees has been proposed as part of the solution to dryland salinity in Australia. The best location in the landscape and the spatial arrangement of trees however, is difficult to determine. This paper presents a case study of a field experiment that compared the water use of tree belts with that of pastures in recharge and discharge areas of a first order catchment in the Central West of NSW, Australia.The recharge tree belt and both pasture sites used very similar amounts of water but the discharge tree belt used double the water of the other three land uses by accessing groundwater. The discharge tree belt operated in an energy-limited environment, transpiring at a rate equivalent to atmospheric demand whereas the other three land uses were all water-limited. From a land management point of view, the establishment of more trees on the discharge site would have the biggest impact on reducing saline discharge and the least impact on the agricultural operations. 相似文献
74.
Saman Bowatte Russell Tillman Andrew Carran Allan Gillingham David Scotter 《Biology and Fertility of Soils》2008,44(6):805-813
This paper explored the potential of application of in situ ion exchange resin membrane (IEM) technique for assessing soil
nitrogen (N) availability and spatial distribution in New Zealand grazed pastures. Field and incubation experiments conducted
to test the technique proved IEM technique to be a useful approach to monitoring the continuous changes in soil mineral N
in pasture soils. The field testing showed that the IEM technique reflects both differences in pool size and mineral N flux,
while 2-M KCl extraction reflects only pool size at the sampling. Testing the effects of residence time, temperature, soil
inorganic N content, and soil water content through diffusion modeling offers further support for using IEM to explore the
complex dynamics of nitrogen availability in pasture soils. 相似文献
75.
76.
Summary Phenotypic and genotypic correlations were examined for four traits in seven populations of maize (Zea mays L.) undergoing recurrent selection. Correlations among grain yield and percentage of grain moisture, root lodging, and stalk lodging were low (|r|<0.3) except for the correlation between grain yield and stalk lodging, which was high and negative. The phenotypic and genotypic correlations agreed well from cycle to cycle within populations. Variation of correlations among populations was not significantly larger than variation among cycles. Heritabilities of these traits generally were high (h2>0.5). Two indices, one that used heritabilities as index weights and one that used relative economic weights (base index) as index weights, were compared with the Smith-Hazel index (optimim index). Relative efficiencies of the two indices, in terms of predicted gains for the individual traits and the composite trait, compared with the Smith-Hazel index, were high. The use of an index in which heritabilities were used as index weights was recommended because:1) the heritabilities were the same as the optimum weights when the traits were uncorrelated, and for the data examined the correlations were low; and 2) heritabilities were computed in routine data analyses and were available at no additional cost.Joint contribution: USDA-SEA-AR and Journal Paper No. 10152 of the Iowa Agriculture and Home Economics Exp. Stn., Ames, Iowa. Project 2194. 相似文献
77.
Bezman Y Bilkis I Winterhalter P Fleischmann P Rouseff RL Baldermann S Naim M 《Journal of agricultural and food chemistry》2005,53(23):9199-9206
The potent odorant beta-damascenone was formed directly from 9'-cis-neoxanthin in a model system by peroxyacetic acid oxidation and two-phase thermal degradation without the involvement of enzymatic activity. Beta-damascenone formation was heavily dependent on pH (optimum at 5.0) and temperature, occurring over the two sequential phases. The first was incubation with peroxyacetic acid at 60 degrees C for 90 min, and the second was at above 90 degrees C for 20 min. Only traces of beta-damascenone were formed on application of only one of the two phases. Formate and citrate solutions produced a much better environment for beta-damascenone formation than acetate and phosphate. About 7 microg/L beta-damascenone was formed from 5.8 mg/L 9'-cis-neoxanthin under optimal experimental condition. The detailed pathway by which beta-damascenone is formed remains to be elucidated. 相似文献
78.
The effect of crop residue incorporation date on soil inorganic nitrogen, nitrate leaching and nitrogen mineralization 总被引:7,自引:0,他引:7
R. D. J. Mitchell R. Harrison K. J. Russell J. Webb 《Biology and Fertility of Soils》2000,32(4):294-301
Delaying cultivation and incorporation of arable crop residues may delay the release of NO3
– and hence reduce leaching. The objective of this study was to investigate the effect of timing of cultivation on the mineralization
and leaching of NO3
– from an arable crop residue. Overwinter N leaching and periodic measurements of soil inorganic N were combined to estimate
net N mineralized after ploughing a crop residue into a free-draining loamy sand soil in central England on six dates from
June 1994 to January 1995. The crop residue was whole green barley with approximately 2% N. N leaching in the two following
winters was increased by the addition of crop residues. Early residue application also tended to increase N leached in the
first winter, largely as a consequence of relatively large losses early in the drainage period. Thus, early incorporation
of crop residues presents a greater leaching risk. The amount of N leached in the second (drier) winter was similar for all
dates of incorporation. At the end of the first winter, inorganic N derived from the crop residue was greatest for earlier
additions: June (40% N applied) > September (30% N applied) > August (20% N applied) > October (19% N applied) > November
(11% N applied) > January (3% N applied). However, at the end of the experiment, there was no evidence that the residues which
had mineralized least by the end of the first winter had, to any significant degree, caught up, and this was confirmed by
the parameters of the equation for first-order decomposition in thermal time. These results indicate that the effect of temperature,
particularly in the early stages of residue mineralization, is complex and interacts with other soil processes in terms of
the fate of the N mineralized.
Received: 19 July 1999 相似文献
79.
ABSTRACT Indian mustard (Brassica juncea Czern.) has the potential to extract zinc (Zn) and other metals from contaminated soils, but the potential to accumulate metals at different levels of exposure is not well documented. The objectives of this research were to assess plant growth and Zn accumulation for different metal-accumulating accessions of Indian mustard grown with various Zn concentrations. In the experiment, three accessions of Indian mustard (426308, 182921, and 211000) were supplied with 12 levels of Zn (ranging from 0.0 to 7.0 mg L?1) for three weeks in solution culture. Accession 426308 had a greater capacity for dry-mass accumulation than the others, but differences among accessions lessened as the concentration of Zn in solution increased. Accessions did not differ in Zn concentrations in shoots, but accession 426308 had a greater potential to accumulate Zn than the other accessions. Elevating the Zn supply in solutions had a limited effect on increasing the total Zn accumulation of shoots. Plants suffered Zn-induced iron (Fe) deficiency if the Zn concentration in solution exceeded 2.0 mg Zn L?1. The level of Zn tolerance of Indian mustard accessions was: 211000 > 182921 > 426308. Maximum Zn accumulation in shoots was approximately 5.0 mg Zn per plant. The phytoextraction potential of Indian mustard may be limited under Zn-contaminated conditions by nutrient disorders and toxic effects of Zn that suppress growth. 相似文献
80.
Connie O��Driscoll Michael Rodgers Mark O��Connor Zaki-ul-Zaman Asam Elvira de Eyto Russell Poole Liwen Xiao 《Water, air, and soil pollution》2011,221(1-4):1-11
Since the 1950s, large areas of upland peat have been afforested in northern European countries. Due to the poor phosphorus (P) adsorption capacity and low hydraulic permeability in blanket peat soil and increased labile P sources, harvesting these blanket peat forests can significantly increase P concentrations in the receiving aquatic systems. This paper briefly reviews the current management practices on the control of P releases from forestry in Ireland and the UK, and proposes a possible novel practice??grass seeding clearfelled areas immediately after harvesting, which should reduce P release from blanket peat forest harvesting. The study was conducted in the Burrishoole Catchment in the west of Ireland. A field trial was carried out to identify the successful native grass species that could grow quickly in the blanket peat forest. The two successful grass species??Holcus lanatus and Agrostis capillaris??were sown in three blanket peat forest study plots with areas of 100, 360, and 660 m2 immediately after harvesting. Areas without grass seeding were used as controls. One year later, the P content in the aboveground vegetation biomass of the three study plots were 2.83, 0.65, and 3.07 kg P?ha?1, respectively, which were significantly higher than the value of 0.02 kg P?ha?1 in the control areas. The water extractable phosphorus in the three study plots were 8.44, 9.83, and 6.04 mg?(kg dry soil)?1, respectively, which were lower than the value of 25.72 mg?(kg dry soil)?1 in the control sites. The results indicate that grass seeding of the peatland immediately after harvesting can quickly immobilize significant amounts of P and warrants additional research as a new Best Management Practice following harvesting in the blanket peatland forest to mitigate P release. 相似文献