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61.
62.
Central nervous system (CNS) tissues from 192 cats with neurological signs were examined histologically, and tissues from 173 of them were later examined immunohistochemically as part of a survey to determine the prevalence of feline spongiform encephalopathy (FSE). One of the cats was from Norway and the others were from Great Britain. The most commonly recorded clinical signs were ataxia, behavioural changes and epilepsy, but none of the cats had histopathological evidence of FSE. The most common organic CNS lesions were non-suppurative encephalomyelitis in 28 per cent, neoplasia in 15 per cent and a heterogeneous group of degenerative encephalopathies in 9 per cent of the cats. A range of minor histological lesions of uncertain significance was also observed. No histological lesions were observed in the tissues of 63 (33 per cent) of the cats. Disease-specific prion protein (PrP(Sc)) was observed in only one of the 173 cats examined by immunohistochemistry.  相似文献   
63.
OBJECTIVE: To determine growth, morbidity, and mortality rates in dairy calves fed pasteurized nonsaleable milk versus commercial milk replacer and compare economics of feeding pasteurized nonsaleable milk versus commercial milk replacer in dairy calves. DESIGN: Clinical trial. ANIMALS: 438 dairy calves. PROCEDURE: Calves were assigned at 1 to 2 days of age to be fed pasteurized nonsaleable milk or a commercial milk replacer until weaned. Body weight was measured at the time of study enrollment and at the time of weaning, and any medical treatments administered and deaths that occurred prior to weaning were recorded. A partial budget model was developed to examine the economics of feeding pasteurized nonsaleable milk versus commercial milk replacer. RESULTS: Calves fed conventional milk replacer had significantly lower rates of gain (-0.12 kg/d [-0.26 lb/d]), lower weaning weights (-5.6 kg [-12.3 lb]), higher risk for treatment during the summer and winter months (odds ratio [OR], 3.99), and higher risk of death during the winter months (OR, 29.81) than did calves fed pasteurized nonsaleable milk. The estimated savings of feeding pasteurized nonsaleable milk, compared with milk replacer, was dollars 0.69/calf per day. The estimated number of calves needed to economically justify the nonsaleable milk pasteurization system was 23 calves/d. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.  相似文献   
64.
The objective of this study was to evaluate associations between herd-level factors and the isolation of Salmonella in calves from dairy farms in Minnesota, Wisconsin, Michigan and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. Salmonella was isolated in fecal samples from 176 (3.8%) of 4673 preweaned calves with 40 (31.0%) of 129 farms having at least one positive calf sample over the course of the study. Multivariable logistic regression using the generalized estimating equations approach was used to evaluate risk factors for Salmonella shedding after adjustment for effects of herd size, season, state of origin and the multiple sampling occasions per herd. Factors retained in the final model that were associated with an increased odds for Salmonella shedding were lack of routine feeding of milk replacer containing antimicrobials to preweaned calves (OR = 2.8, 95% CI: 1.4, 5.8), use of maternity housing as a hospital area for sick cows more than once a month (OR = 2.1, 95% CI: 1.1, 4.0), and cow prevalence level by visit, categorized into the following four-levels: ≥20% (OR = 11.6, 95% CI: 5.7, 23.7), 10–19.9% (OR = 4.7, 95% CI: 2.0, 11.5), 0.1–9.9% (OR = 3.6, 95% CI: 1.5, 8.7) and 0% (reference level). Herd size was not associated with Salmonella shedding in the final multivariable model.  相似文献   
65.
The effect of colostrum or serum feeding on subsequent rotavirus infections was investigated in neonatal gnotobiotic lambs. Immunity after feeding colostrum did not depend on absorption of passively acquired antibody into the circulation. Protection against clinical disease depended on the volume of colostrum ingested. The protection afforded by feeding serum was specific, since serum free of rotavirus antibody failed to confer protection. Immune serum fed at a rate of 2.5 ml per kg twice daily protected against rotavirus infection. Also, it was shown by intraperitoneal inoculation of immune serum that protection could occur in the absence of ingested antibody, presumably by transfer of antibody into the gut. The implications of these findings for immunoprophylaxis of rotavirus diarrhoea in lambs and calves are discussed.  相似文献   
66.
67.
Medium‐weight hybrid pullets were used to test the effects of (a) providing red instead of white light from 3 to 18 weeks of age and (b) feeding a diet containing 15\ per cent crude protein from 6 to 12 weeks followed by one containing 12 \ per cent crude protein to 18 weeks of age instead of feeding the first‐mentioned diet from 8 to 18 weeks of age.

Results showed that these alternative rearing practices had only a small influence on performance. On balance, any immediate advantages resulting from the use of red light and/or low‐protein food were outweighed by disadvantages which arose in the subsequent laying period.  相似文献   

68.
The efficacy of a multicomponent clostridial vaccine containing Pasteurella haemolytica antigens was tested in specific pathogen free or conventionally reared lambs exposed to experimental infection with P haemolytica serotypes A1, A2 or A6. In four experiments assessment was based upon the findings of clinical, pathological and bacteriological examinations. Three experiments carried out in conventionally reared lambs demonstrated protection against challenge infection with P haemolytica serotypes A1, A2 and A6 in vaccinated lambs. However, the inconsistency of the disease induced in these experiments emphasised the need to perform definitive studies in specific pathogen free conditions. The final experiment was carried out with specific pathogen free lambs and confirmed the efficacy of the multicomponent clostridial vaccine containing P haemolytica antigen in protecting against the effects of infection with P haemolytica serotype A6. In addition, this experiment indicated that the inclusion of several components in a vaccine did not affect the efficacy of an individual antigenic component.  相似文献   
69.
Lysozyme is a 1,4-β-N-acetylmuramidase that has antimicrobial properties. The objective of this experiment was to determine the effect of a purified granulated lysozyme, compared with antibiotics, on growth performance, small intestinal morphology, and Campylobacter shedding in 10-d-old pigs. Forty-eight pigs (n = 16 per treatment), with an initial BW of 4.0 ± 0.1 kg (P > 0.40), were weaned at 10 d of age, blocked by litter and sex, and assigned to pens (8 pigs/pen). Each block was randomly assigned to consume 1 of 3 liquid dietary treatments for 14 d: a control diet, the control diet + lysozyme (100 mg/kg of diet), or the control diet + antibiotics (neomycin and oxytetracycline, 16 mg/kg of diet). Pigs were weighed and blood was sampled on d 0, 7, and 14. Blood was analyzed for plasma urea N and IgA. After 14 d of treatment, pigs were killed and samples of the jejunum and ileum were collected and fixed to measure villus height and crypt depth. Rectal swabs were taken on d 0, 7, and 14 of treatment, and samples of ileal and cecal contents were taken at d 14 of treatment to determine the presence of Campylobacter. Pigs consuming lysozyme and antibiotics gained BW at a faster rate than did control pigs over the course of the study (402 ± 12 and 422 ± 14 g/d, respectively, vs. 364 ± 14 g/d; P < 0.02), resulting in heavier ending BW (9.9 ± 0.3, 9.9 ± 0.3, and 9.0 ± 0.2 kg for pigs in the lysozyme, antibiotic, and control groups, respectively; P < 0.03). Immunoglobulin A decreased and plasma urea N increased over the course of the study (P < 0.1), regardless of dietary treatment (P > 0.6). Crypt depth was increased in pigs fed lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet, in both the jejunum (60.0 ± 2.8 and 62.2 ± 3.0 μm, respectively, vs. 50.7 ± 3.1 μm; P < 0.03) and ileum (76.0 ± 7.5 and 72.2 ± 5.0 μm, respectively, vs. 52.4 ± 3.5 μm; P < 0.02). Villus height did not differ in the jejunum (P > 0.2) but was increased in the ileum of pigs consuming the lysozyme- and antibiotic-treated diets, compared with pigs fed the control diet (312 ± 20 and 314 ± 10 μm, respectively, vs. 263 ± 15 μm; P < 0.4). Small intestinal total mucosa and mucosal protein concentrations, as well as disaccharidase-specific activities, were not altered by lysozyme or antibiotics (P > 0.05). Campylobacter was detected in 27% of control samples but in only 5% of samples from pigs fed antibiotics and 8% of samples from pigs fed lysozyme (P < 0.01). Thus, granulated lysozyme is a suitable alternative to antibiotics for 10-d-old pigs consuming manufactured liquid diets.  相似文献   
70.
The calpain protease system, in particular, μ-calpain is involved in the disassembly of specific myofibrillar proteins, resulting in tenderization of meat postmortem. Given the size, complexity, and integral nature of titin to the structure of the sarcomere, it is plausible that the length of a sarcomere may alter the susceptibility of various domains of titin to cleavage by the calpains. Therefore, we hypothesized titin degradation differs in a sarcomere-length-dependent manner in beef. After slaughter, beef carcasses were split and sides were either suspended by the Achilles tendon (normal suspension, NS) or by the aitchbone (hip suspension, HS). Immediately after suspension, samples were dissected from the LM, psoas major (PM), and semitendinosus (STN) muscles to serve as 0-d controls. After 24 h, 4 steaks were removed from each muscle and randomly assigned to 1-, 4-, 7-, or 10-d aging treatments. After the assigned aging period, myofibrils were purified for determination of sarcomere length. Warner-Bratzler shear force analysis was also performed to evaluate differences in tenderness. Muscle proteins were solubilized and subjected to SDS-VAGE (vertical agarose gel electrophoresis) to evaluate titin degradation. Sarcomere lengths differed (P < 0.0001) between contralateral muscles of NS and HS carcasses. Quantification of SDS-VAGE gels revealed less (P < 0.05) intact titin in the PM muscle of NS carcasses at each aging period compared with the PM of HS carcasses. No significant differences (P > 0.05) were detected in the disappearance of intact titin among suspension methods in the LM or STN. These data demonstrate that suspension method alters proteolysis of titin and suggest an increase in sarcomere length may contribute to the susceptibility of titin to postmortem proteolysis in beef.  相似文献   
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