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排序方式: 共有191条查询结果,搜索用时 15 毫秒
1.
The objective of this study was to determine the dietary phosphorus (P) requirement of juvenile Atlantic salmon, Salmon salar L. Triplicate groups of fish (mean initial weight 1.4 g) were fed semipurified, casein-gelatine-based diets containing one of five levels of P (4, 8, 10, 15 and 25 g kg−1 ) from Ca(H2 PO4 )2 ·H2 O, or a commercial feed (17 g kg−1 P) for 9 weeks. Weight gains did not differ significantly among treatment groups fed the experimental diets but were slightly less than gains in fish fed the commercial feed. Feed efficiency (wet weight gain/dry feed consumed) was similar in all groups, averaging 1.45. Availability of dietary P, estimated from apparent retention and apparent digestibility, was 86%. Whole-body P concentrations declined in fish fed diets containing less than 10 g kg−1 P. Fitting a logistic curve to dietary P vs. whole-body P concentrations indicated that a minimum of 11 g kg−1 dietary P (9 g kg−1 digestible P) was required by juvenile Atlantic salmon to maintain whole-body P concentrations at initial levels. Calculation of a dietary requirement using a simple factorial model which incorporated measurements of P availability, feed efficiency and normal whole-body P concentration indicated that the dietary requirement was approximately 10 g kg−1 . The dietary requirement established in this study (10–11 g kg−1 ) is higher than previously reported for Atlantic salmon or other fishes. Possible reasons for the wide range of reported dietary P requirements in fishes are discussed. 相似文献
2.
A wide range of variation in concentration of manganese was found in the blood of 51 cycling ewes although no significant differences were evident (P less than 0.05) between days 4, 11 and 15 (day 0 = day of estrus) of the estrous cycle. In addition, no differences (P less than 0.05) were found in the manganese concentrations of various soft tissues of 15 ewes, killed on day 4 (five animals), day 11 (five animals) or during anestrus (five animals). The highest concentration of manganese was present in the liver, pancreas and kidney cortex, tissues which are rich in mitochondria. Among the tissues of the reproductive tract, the corpus luteum showed the highest manganese concentration and the level increased significantly (P less than 0.01) between days 4 and 11 suggesting that this trace element may be closely related to the metabolic and possible functional characteristics of this endocrine gland. Uterine horn and caruncles contained greater manganese concentrations than other components of the reproductive tract. The significance of these findings in relation to the effect of manganese intake on ewe fertility remains to be assessed. 相似文献
3.
Effect of lameness on milk yield in dairy cows 总被引:1,自引:0,他引:1
Hernandez J Shearer JK Webb DW 《Journal of the American Veterinary Medical Association》2002,220(5):640-644
OBJECTIVE: To examine the relationship between lameness and milk yield in dairy cows. DESIGN: Cohort study. ANIMALS: 531 dairy cows. PROCEDURE: Cows affected with lameness were classified into 1 of 3 groups on the basis of type of diseases or lesions observed, including interdigital phlegmon (foot rot), papillomatous digital dermatitis (foot warts), or claw lesions. Cows not affected with lameness were classified as healthy. From Dairy Herd Improvement Association records, 305-day mature equivalent milk yield data were collected at the end of lactation or when the cow left the herd. Milk yield was compared between cows affected with lameness and healthy cows. RESULTS: 167 (31%) cows were affected with lameness during lactation. Lame cows had claw lesions (60%), papillomatous digital dermatitis (31%), or interdigital phlegmon (9%). Milk yield in lame cows with interdigital phlegmon (mean, 17,122 lb) was significantly less, compared with healthy cows (19,007 lb). CONCLUSIONS AND CLINICAL RELEVANCE: In this herd, interdigital phlegmon was associated with a 10% decrease in milk production. Lame cows with claw lesions or papillomatous digital dermatitis produced less milk than healthy cows, but the difference was not significant. 相似文献
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The occurrence of equine arteritis virus in Australia 总被引:2,自引:0,他引:2
This paper reports the first isolation of equine arteritis virus (EAV) in Australia and serological evidence of exposure to EAV in Australian horses. Twelve Standardbred stallions imported from North America were found to shed EAV in semen. One hundred and seven stallions were tested for serum antibodies to EAV and 73% of Standardbred stallions tested were seropositive as compared to 8% of Thoroughbred stallions. Serum antibody was detected in 71% of Standardbred mares, 6% of Standardbred racehorses and 1% of Thoroughbred mares and racehorses. Examination of stored serums demonstrated that EAV had been present in Australia since at least 1975. 相似文献
7.
The safety and anthelmintic efficacy of clorsulon (7 mg/kg of body weight, orally) given concurrently with ivermectin (0.2 mg/kg, subcutaneously) for control of Fasciola hepatica were evaluated in 75 crossbred beef cattle. Twenty-three control animals were given only ivermectin. Fluke egg counts were significantly lower (P less than 0.0001) in clorsulon-treated animals by day 14 after treatment than before treatment (base line) and were significantly lower (P less than 0.005) after treatment in clorsulon-treated animals than in controls. There was no significant change in fluke egg counts of controls after treatment. The efficacy of clorsulon in reducing F hepatica egg counts was 99%. Clorsulon showed poor efficacy against paramphistomes. Adverse reactions were not observed. 相似文献
8.
Financial comparison of three testing strategies for detection of estrus in dairy cattle 总被引:1,自引:0,他引:1
H O Mohammed S Loefler J Shearer 《Journal of the American Veterinary Medical Association》1990,196(6):865-869
Three commercial tests that measure progesterone content in milk were evaluated for accuracy of estrus detection. The tests were evaluated on 96 milk samples collected from Holstein cows at a commercial dairy farm in central Florida. The test results were compared with the results of radioimmunoassay on the same sample. Comparisons were made by calculating the sensitivities, specificities, and predictive values. The significance of the statistical association between the tests and the radioimmunoassay was evaluated by use of the McNemar chi 2 test. Decision-tree analysis was used to determine the most useful testing strategy, considering both cost and accuracy. The cowside progesterone assay on estrus-mount detector-positive cows was more profitable than use of estrus-mount patches alone. The return on investment was higher with the cowside test, making it preferred as a field test for detecting estrus. 相似文献
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The effect of phosphite concentration on lesion development by Phytophthora cinnamomi in stems and roots of Banksia grandis and Eucalyptus marginata and in stems of Banksia coccinea was assessed during a 4.3 year period after stem injection of phosphite. Lesion length 6 weeks after inoculation was significantly less in roots of B. grandis trees that had been stem injected with three concentrations of phosphite (50, 100 and 200 g phosphite/l) at two rates (1 and 2 ml/cm of stem circumference) compared with the not‐injected control. With the exception of B. grandis trees injected with 50 g phosphite/l, lesion length for the high rate was not significantly different to the low rate. In roots of E. marginata, lesion development in response to phosphite was different to that in roots of B. grandis; lesion length in roots did not differ significantly between phosphite concentration and rate. Lesion length and girdling in stems of B. grandis and E. marginata was significantly less in those injected with phosphite than in not injected stems. One year after injection, callus tissue had contained lesions in stems injected with phosphite. By 4.3 years after injection of both hosts there was a steep significant negative linear relationship between phosphite concentration and either lesion length or girdling, with greatest lesion development in not injected stems and least in stems injected with 100 g phosphite/l. Recovery of P. cinnamomi from lesion margins 1 year after injection, was significantly less in trees injected with phosphite than in not injected trees. The amount of plant death reflected containment of lesion extension and girdling, and reduction of recovery of P. cinnamomi with phosphite concentration; 4.3 year after injection there was a steep significant negative linear relationship between phosphite concentration and percentage of plant death. In contrast to B. grandis and E. marginata, there was a U‐shaped non‐linear relationship between phosphite concentration and effectiveness of phosphite in controlling lesion extension and girdling in B. coccinea. Containment of lesion extension and girdling with time was greatest for B. coccinea stems injected with 25 g phosphite/l, least for stems not injected, and intermediate in stems injected with 50 and 100 g phosphite/l. As in B. grandis and E. marginata, containment of lesion extension and girdling in B. coccinea with phosphite concentration was reflected in the amount of plant death. The non‐linear response to phosphite of some plant species indicated that injected concentration for B. coccinea should not exceed 50 g phosphite/l, whereas injected concentrations of up to 100 g phosphite/l could be recommended for B. grandis. Longevity of action of phosphite for 4–5 years in native plant species after one injection makes phosphite injection a practical control option for the control of P. cinnamomi disease front extension and the protection of threatened flora. Research into the effect of factors affecting longevity of action of phosphite would facilitate optimization of timing of injection. 相似文献