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441.
Duffy KR Wellard CJ Markham JF Zhou JH Holmberg R Hawkins ED Hasbold J Dowling MR Hodgkin PD 《Science (New York, N.Y.)》2012,335(6066):338-341
In response to stimulation, B lymphocytes pursue a large number of distinct fates important for immune regulation. Whether each cell's fate is determined by external direction, internal stochastic processes, or directed asymmetric division is unknown. Measurement of times to isotype switch, to develop into a plasmablast, and to divide or to die for thousands of cells indicated that each fate is pursued autonomously and stochastically. As a consequence of competition between these processes, censorship of alternative outcomes predicts intricate correlations that are observed in the data. Stochastic competition can explain how the allocation of a proportion of B cells to each cell fate is achieved. The B cell may exemplify how other complex cell differentiation systems are controlled. 相似文献
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444.
Bareroot Changbai larch (Larix olgensis Henry.) seedlings were reared with inorganic fertilizer (nitrogen (N):phosphorus (P) = 1:1, W/W) applied at a rate of 100
(F100) or 200 kg N ha−1 (F200) with (+) or without (−) chicken manure as a soil amendment (O) in north-eastern China. An unfertilized control treatment
was included. Inorganic and organic fertilizer treatments tended to increase soil ammonium, nitrate, available P, total P,
organic carbon content and electrical conductivity, and biomass and N concentration in seedlings. Organic amendment improved
first order lateral root number, tap root length, fine root morphology (length, surface area, volume) in seedlings, while
the F100 treatment increased N accumulation in needles and stems compared to the F200 treatment, on average. Most fertilizer
treatments tended to increase P content in combined stems and roots, but F200 − O and F100 + O treatments diluted P in needles.
Organic amendment combined with inorganic fertilizer at a rate of 100 kg N and P ha−1 is recommended to improve seedling growth and N reserves in woody tissues. 相似文献
445.
Hawkins MG Kass PH Zinkl JG Tell LA 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2006,35(2):219-225
BACKGROUND: To the authors' knowledge, on the basis of sample type, storage condition, or hemolysis, differences in serum and plasma biochemical values have not been evaluated in orange-winged Amazon parrots (Amazona amazonica). OBJECTIVES: The purpose of this study was to compare values for biochemical analytes in serum vs plasma, fresh vs frozen plasma, and nonhemolyzed vs hemolyzed samples in orange-winged Amazon parrots. We also compared differences in serum and plasma yield from whole-blood aliquots. METHODS: Fifteen biochemical analytes were evaluated in paired serum and plasma, fresh and frozen plasma, nonhemolyzed and hemolyzed serum and plasma samples from orange-winged Amazon parrots (n = 10) using a wet reagent analyzer. Hemolysis was assessed qualitatively (visually) and quantitatively (hemoglobin [Hgb] measured spectrophotometrically). Serum and plasma yields from 500-microl whole-blood aliquots were determined from centrifuged samples. RESULTS: Analyte values significantly differed among sample groups, but were still within published reference intervals, with the exception of increases in potassium concentration in markedly hemolyzed serum and plasma samples. Clinically important changes in hemolyzed serum and plasma samples included increases in potassium, phosphorus, and albumin concentrations and lactate dehydrogenase activity. The degree of hemolysis assigned qualitatively did not correlate with quantitative Hgb concentration. A significantly greater yield of plasma (288 +/- 13 microL) than serum (241 +/- 44 microL) was obtained. CONCLUSIONS: Significant differences may occur in different sample types, however, only changes in potassium, phosphorus, albumin, and lactate dehydrogenase values in hemolyzed samples were considered clinically relevant. Lack of agreement between qualitative and quantitative Hgb concentration indicates the unreliability of visual estimation. Based on higher sample yield, and lack of clinically relevant differences from serum, plasma is a better sample choice for clinical chemistry analysis in birds. 相似文献
446.
Epizootiologic studies of ovine virus abortion 总被引:5,自引:0,他引:5
447.
Experiments were conducted to evaluate the effects of dietary energy density or genetic background on protein and fat gain of growing cattle. In Exp. 1, 24 Limousin steers were used in a growing-finishing trial. A 2 X 2 factorial arrangement was used with steers randomly allotted to four treatment combinations and fed the following diets: 80% concentrate, high moisture corn-corn silage diet (HI) or a corn silage diet (LO) during both the growing (GRO) and(or) the finishing (FIN) phases. Body composition for both experiments was determined by a deuterium oxide dilution technique. Empty body weight gains were greater (P less than .05) for HI during GRO, FIN and the total trial. Daily protein gains (DPG) were greater (P less than .05) for HI during GRO and FIN, while cattle receiving HI during at least FIN had the greatest (P less than .05) overall DPG. Daily fat gains (DFG) followed the pattern of DPG, being more rapid (P less than .05) for cattle fed HI during either GRO or FIN. Cattle fed the HI diet also tended to be more energetically efficient. In Exp. 2, large frame (LG) and small frame (SM) cattle were used for the evaluation of frame size effects on protein and fat deposition. Steers were individually fed an 80% concentrate, corn-based diet during the entire trial. Average daily gains and daily dry matter intake (P less than .05, P less than .01) were greater for LG, while feed efficiency was similar for both cattle types. Large cattle had greater (P less than .05) DPG than SM cattle, however, DFG were not different. Small frame steers were energetically more efficient (P less than .05), apparently due to composition of gain difference. 相似文献
448.
The effect of erythrosin B and visible light on 3rd stage larvae of gastrointestinal nematodes of naturally-infected cattle was studied. Cattle were treated orally with erythrosin B at dosages of 30 and 40 mg kg-1 day-1 for as many as 17 days. Feces from treated and untreated animals were collected and prepared for culture. Third stage larvae were then collected by Baermannization and exposed to light. Both sunlight and artificial fluorescent light were shown to be toxic to 3rd-stage-larvae after treatment with erythrosin B. This toxic reaction was significant after only 2 consecutive daily treatments. 相似文献
449.
SUMMARY A jetting fluid containing 7.5% w/v ivermectin, which was diluted to 0.03 mg/mL in water and applied using a standard hand jetting technique, was assessed for its efficacy in treating blowfly strikes on Merino sheep. Strikes were induced on sheep held under insectary conditions using laboratory-reared Lucilia cuprina. All struck sheep jetted at 28,48 or 72 hours after exposure to flies were successfully treated. All 1st, 2nd and early 3rd instar larvae were killed within 24 hours of treatment. 相似文献
450.
J A Hawkins R K McDonald B J Woody 《Journal of the American Veterinary Medical Association》1987,190(12):1572-1573
Sarcoptes scabiei infestation was diagnosed in a cat. Clinical signs included thick, crusty, exudative dermatitis on the feet, caudal aspect of the thighs, and tail. Paronychia and dystrophic nails also were observed. The course of the disease was chronic. Concomitant and potentially predisposing additional health problems were suspected, but were not confirmed. 相似文献