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81.
D. Levy 《Potato Research》1983,26(4):315-321
Summary The effect of repeated short periods of water stress during the hot season on six potato cultivars was investigated. The number
of tubers per plant tended to decrease in response to water stress in cultivars which had more than 9.8 tubers per control
plant (Désirée, Alpha, Elvira). In the other cultivars, no consistent effect of water stress on tuber number per plant was
observed. Except for Spunta, the percentage of large tubers (>60 g/tuber) was reduced in the water-stressed plants. Consequently,
the average weight of these tubers was greater than that of tubers harvested from the unstressed plants, indicating that the
sink force of the individual tuber was not impaired by drought. However, tuber yield per plant was reduced due to drought
in all cultivars tested.
The smallest decrease in dry matter accumulation as well as the greatest lowering of the osmotic potential in the tuber tissue
was found in Alpha. No consistent effect of water stress on the percentage of misshapen and sprouting tubers was observed,
indicating the marked effect of the high temperature on these traits.
Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, No 310-E, 1981 series. This
investigation was sponsored by a grant from the Ministry for Development Cooperation of the Netherlands. 相似文献
82.
Summary Diffusive leaf resistance and transpiration rate were assessed in various potato genotypes includingS. tuberosum cvs. Atlantic, Cara, Alpha and Désirée,S. phureja clone PP5, a hybrid of Atlantic X PP5, and two anther-derived tetraploids of PP5. Resistance and transpiration were assessed
with an LI-1600 steady state porometer on well-watered plants and differences in leaf resistance and transpiration rate among
genotypes were obtained. These results imply that water economy may be improved by genotypes exhibiting small water losses.
Transpiration rates calculated by dividing the weight of water transpirted per second by the area of the plant's leaflets,
were lower than transpiration rates of young expanding leaflets assessed with the porometer. Nevertheless, the relative differences
among genotypes were evident and a similar relationship among genotypes was maintained in the two measures. Cv. Alpha had
lower transpiration rates, compared to Cara and Désirée, corresponding with its greater stomatal resistance. 相似文献
83.
84.
85.
D. Levy Y. Itzhak E. Fogelman E. Margalit R. E. Veilleux 《American Journal of Potato Research》2001,78(3):167-173
The cultivars Ori, Idit, Zohar, and Zahov have been bred specifically for adaptation to the Mediteranean climate: Ori and Idit are early tablestock cultivars, Idit is suited for “mini potatoes” (20 to 35 mm in diameter); Zohar is a midseason tablestock cultivai-, and Zahov is used as an early chipstock cultivar. The cultivars can be grown in either of the two main seasons in the Mediterranean region: the spring season (January through July) and the winter season (September through March). The cultivars have rapid emergence and early tuber set, they are tolerant to high temperatures and drought, and are not susceptible to external or internal defects. In field experiments, Idit yields were lower than the cultivar checks (Alpha, Nicola, or Desiree) in six of seven trials. However, the attractive appearance of the small oval tubers (20-35 mm in diameter) and the good aroma of the baked tubers are advantages. Yield of Ori and Zohar occasionally exceeded those of cultivar checks, and their yellowish skin, especially in sandy soils, is an advantage. Yields and tuber dry matter content of the early-maturing cultivar Zahov were similar to Hermes, a standard chipstock cultivar commonly used in Israel. The early maturation of Zahov is desirable to extend the harvest season. 相似文献
86.
Summary The effect of the dyked furrow technique on potato yield was tested for 3 years in a commercial field on a sandy soil. Dykes,
creating a surface storage capacity of 60 mm of water, were constructed in the furrows with special equipment after planting.
Another implement, harnessed to the front of the tractor, was used to remove the dykes before harvesting. During 2 of the
3 years, the yield in the dyked furrows was 18% higher than that in the control plots. The dykes closely maintained the original
volume of the ridges. The dykes seemed not to have any deleterious effect on mechanical harvesting since the percentage of
tare (i.e. clods, soil and plant residue) and of rotten tubers were similar to the control. 相似文献
87.
88.
Irrigation with saline–sodic water imposes sodic conditions on the soil and reduces the soil’s productivity. We hypothesized
that replacing saline–sodic irrigation water with lesser saline–sodic treated waste water (TWW), albeit with higher loads
of organic matter and suspended solids, might help sodic soils regain their structure and hydraulic conductivity. We studied
hydraulic conductivity (HC), aggregate stability and clay swelling of a soil from the Bet She’an Valley, Israel using samples
taken from a non-cultivated field (control), and plots irrigated with TWW, saline–sodic Jordan River (JR) water, and moderately
saline–sodic spring (SP) water. Soil samples were taken at the end of the irrigation season (autumn 2005) and at the end of
the subsequent rainy season (spring 2006). In the HC and the aggregate stability determinations, for both sampling seasons,
the TWW-irrigated samples gave significantly higher values than the SP- and JR-irrigated samples, but lower than the samples
from the control plot. The autumn samples exhibited, generally, higher HC and lower swelling levels compared with the spring
samples. Conversely, aggregate stability of the spring samples was higher than that of the autumn samples. These seasonal
changes in the results of the three tests were associated with seasonal changes in the salinity and sodicity of the soils.
Contributions from the Agricultural Research Organization, The Volcani Center, Bet-Dagan 50250, Israel. No. 601/2007 series. 相似文献
89.
ABSTRACT We have developed a scale of differential hosts that enables the determination and comparison of level of resistance to Tomato yellow leaf curl virus (TYLCV) expressed by resistant tomato lines or by individual plants in a segregating population. The scale is composed of seven different homozygous tomato genotypes that exhibit different levels of TYLCV resistance, ranging from fully susceptible to highly resistant. The differential hosts composing the scale were inoculated with TYLCV under greenhouse conditions. Four weeks after inoculation the plants were evaluated for disease symptom severity, and virus DNA titer was determined. The different genotypes were arranged in the scale according to symptom severity score. The different genotypes were then tested under different environmental conditions, inoculated at different ages, and tested in a field experiment assaying TYLCV-induced yield reduction. While the symptom severity score of each individual resistant genotype changed under different environmental conditions, the relative position on the scale did not alter, except for one genotype. Thus, to evaluate disease resistance of a given tomato genotype, the genotype in question should be inoculated alongside the differential hosts composing the scale, and within 4 weeks one can determine the relative level of resistance of the tested genotype. 相似文献
90.
A low molecular weight poly(ethyleneoxide)-poly(butadiene) (PEO-PB) diblock copolymer containing 50 weight percent PEO forms gigantic wormlike micelles at low concentrations (<5 percent by weight) in water. Subsequent generation of free radicals with a conventional water-based redox reaction leads to chemical cross-linking of the PB cores without disruption of the cylindrical morphology, as evidenced by cryotransmission electron microscopy and small-angle neutron scattering experiments. These wormlike rubber micelles exhibit unusual viscoelastic properties in water. 相似文献