全文获取类型
收费全文 | 927篇 |
免费 | 20篇 |
专业分类
林业 | 63篇 |
农学 | 1篇 |
基础科学 | 1篇 |
50篇 | |
综合类 | 401篇 |
农作物 | 20篇 |
水产渔业 | 4篇 |
畜牧兽医 | 374篇 |
园艺 | 3篇 |
植物保护 | 30篇 |
出版年
2012年 | 62篇 |
2011年 | 46篇 |
2010年 | 10篇 |
2008年 | 41篇 |
2007年 | 49篇 |
2006年 | 62篇 |
2005年 | 42篇 |
2004年 | 52篇 |
2003年 | 46篇 |
2002年 | 37篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1986年 | 8篇 |
1982年 | 12篇 |
1977年 | 7篇 |
1973年 | 7篇 |
1970年 | 8篇 |
1969年 | 9篇 |
1967年 | 6篇 |
1966年 | 6篇 |
1963年 | 12篇 |
1958年 | 8篇 |
1957年 | 10篇 |
1948年 | 6篇 |
1947年 | 10篇 |
1945年 | 5篇 |
1944年 | 8篇 |
1942年 | 5篇 |
1940年 | 5篇 |
1938年 | 5篇 |
1931年 | 5篇 |
1930年 | 5篇 |
1925年 | 5篇 |
1917年 | 5篇 |
1915年 | 5篇 |
1912年 | 5篇 |
1911年 | 5篇 |
1909年 | 5篇 |
排序方式: 共有947条查询结果,搜索用时 15 毫秒
31.
Moore AH 《The Journal of small animal practice》2003,44(7):326-329
Three dogs with mycotic rhinitis were treated with a proprietary wound dressing product intended to produce a sustained release of povidone-iodine. All of the dogs had been refractory to other treatments. One dog had extensive soft tissue involvement, including extension into the orbital tissues, and another had evidence of involvement of the supporting bones of the nose. In all cases, the affected nasal cavity and/or frontal sinus was exposed via a dorsal approach and partial turbinectomy was performed. The wound dressing was applied and retained with a 'tie-over' dressing. The dressing was replaced every 48 to 72 hours until all exposed tissue was covered by healthy granulation tissue, at which time the rhinotomy was closed by soft tissue reconstruction. There was no evidence of recurrence of the fungal infection at follow-up times of up to 20 months postsurgery. 相似文献
32.
Growth and Apparent Absorption of Minerals in Broiler Chicks Fed Diets with Low or High Tannin Contents 总被引:5,自引:1,他引:4
Sorghum grains with low (0.28 per cent catechin equivalent (%CE) or high (1.36 %CE)) tannin contents were used to study the effect of tannin on growth and on the apparent absorption of Ca, P, Mg, Na, K, Fe and Co by chickens. High-tannin sorghum caused a highly significant (p0.01) reduction in the weight gain and feed intake of broiler chicks compared to low-tannin sorghum and increased the feed conversion ratio (p0.01). The amount of tannin did not affect mortality. The apparent absorption of Ca, P, Mg, Na, K, Fe and Co was reduced (p0.01) by feeding sorghum grains with a high tannin content. 相似文献
33.
van den Broek AH Huntley JF Halliwell RE Machell J Taylor M Miller HR 《Veterinary immunology and immunopathology》2003,91(2):105-117
We have previously shown that infestation with Psoroptes ovis induces an IgE response and intense tissue eosinophilia, typical of a Type I hypersensitivity response [Parasite Immunol. 22 (2000) 407]. Intradermal tests (IDSTs) suggest that there are also delayed and Arthus-type responses to this parasite. In order to study the nature of ovine cutaneous reactions to P. ovis, na?ve controls and experimentally infested sheep (n = 5) were challenged intradermally with mite antigen. Challenge elicited immediate (P < 0.001) and delayed (P < 0.005) wheal reactions in sensitised sheep. At 6 (P < 0.02) and 30 h (P < 0.001) the predominant infiltrating cells were eosinophils. To explore the role of circulating antibodies, na?ve sheep (n = 5) were subjected to Prausnitz-Kustner (PK) tests. These elicited immediate (P < 0.02) but not delayed wheal reactions. At 6 h eosinophils (P < 0.001) dominated the infiltrate. These results suggest that P. ovis allergens provoke an IgE-dependent immediate and late phase response and a cell-mediated eosinophil-rich delayed-type hypersensitivity response (ER-DTH). 相似文献
34.
A live attenuated Mycoplasma gallisepticum vaccine, ts-11, has been used for control of M gallisepticum in several countries. The rapid serum agglutination test is usually used as an indicator of flock response to vaccination; however, in some flocks, the detected response may be weak or absent. We investigated whether the low level, or lack, of systemic antibodies in ts-11-vaccinated flocks is correlated with susceptibility to infection after challenge with a virulent M. gallisepticum strain. Birds from 2 separate ts-11-vaccinated commercial flocks with no, or weak, rapid serum agglutination responses (at 11 or 14 wk postvaccination) were randomly selected and subjected to aerosol challenge with either M gallisepticum strain Ap3AS or sterile mycoplasma broth. A group of nonvaccinated specific-pathogen-free chickens at similar age were also exposed to aerosolization with M. gallisepticum strain Ap3AS and used as positive controls. Postmortem examination of the birds, performed 2 wk after challenge, revealed no significant difference in microscopic tracheal lesions or mucosal thicknesses between the ts-11-vaccinated field birds irrespective of their aerosolization treatment. However, both microscopic tracheal lesions and tracheal mucosal thicknesses of nonvaccinated challenged birds were significantly greater than those of ts-11 vaccinates. Hence, broiler breeders vaccinated in the field showed significant protection against virulent M. gallisepticum challenge even when no serum antibody was detected by rapid serum agglutination test. These results reveal that seroconversion detected by rapid serum agglutination test after ts-11 vaccination is not a reliable predictor of protection against M. gallisepticum infection. The possible significance of local antibody response and cell-mediated immunity against M. gallisepticum infection is discussed. 相似文献
35.
Stelzleni AM Perkins TL Brown AH Pohlman FW Johnson ZB Sandelin BA 《Journal of animal science》2002,80(12):3150-3153
The objective of this study was to estimate genetic parameters for real-time ultrasound measurements of longissimus muscle area (LMA), 12th rib backfat thickness (FT), percent intramuscular fat (IMF), and yearling weight (YW) for 1,299 yearling Brangus bulls and heifers. A single ultrasound technician performed all measurements. The number of observations was 1,298, 1,298, 1,215, and 1,170 for LMA, FT, IMF, and YW, respectively. Genetic parameters were estimated for each trait using single- and multiple-trait derivative-free restricted maximal likelihood. Fixed effects were contemporary group (defined as same sex, same age within six months, and same environment), and days of age as a covariate. Correlations were estimated from two-trait models. Heritabilities for LMA, FT, IMF, and YW were 0.31, 0.26, 0.16, and 0.53, respectively. Genetic correlations between LMA and FT, LMA and IMF, LMA and YW, FT and IMF, FT and YW, and IMF and YW were 0.09, 0.25, 0.44, 0.36, 0.42, and 0.31, respectively. Yearling live animal ultrasonic measurements can be used as a selection tool in breeding cattle for the improvement of carcass traits. 相似文献
36.
Sandelin BA Brown AH Brown MA Johnson ZB Kellogg DW Stelzleni AM 《Journal of animal science》2002,80(12):3073-3076
Mature weight and rate of maturing were estimated in 177 Angus, Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte-infected tall fescue over a 4-yr period to evaluate genotype x environment interactions. Data were collected every 28 d until cows were approximately 18 mo of age and then at prebreeding, postcalving, and weaning of calf. All cows with weight data to at least 42 mo of age were included in the analysis. Mature weight and rate of maturing were estimated using the three-parameter growth curve model described by Brody (1945). Data were pooled over year and analyzed by the general linear model procedure of SAS. Included in the models for mature weight and rate of maturing were the independent variables of genotype, environment, and genotype x environment interaction. There was a genotype x environment interaction (P < 0.01) for mature body weight (BW) but not for rate of maturing. Angus cows grazing fescue pastures had greater (P < 0.01) mean mature BW than Angus x Brahman cows grazing bermudagrass (611 +/- 17 vs 546 +/- 16 kg). Angus x Brahman cows grazing bermudagrass had lower (P < 0.05) mean mature BW than Brahman x Angus cows grazing bermudagrass or endophyte-infected fescue and Brahman cows grazing bermudagrass (546 +/- 16 vs 624 +/- 19, 614 +/- 22 and 598 +/- 20 kg, respectively). Brahman cows grazing endophyte-infected fescue had smaller (P < 0.05) mean mature BW than all genotype x forage combinations except for Angus x Brahman cows grazing bermudagrass. Angus cows had a smaller (P < 0.05) mean rate of maturing than Angus x Brahman and Brahman x Angus cows (0.039 +/- 0.002 vs 0.054 +/- 0.002 and 0.049 +/- 0.002%/mo, respectively), respectively, and Angus x Brahman cows had a larger (P < 0.05) mean rate of maturing than Brahman x Angus and Brahman cows (0.054 +/- 0.002 vs 0.049 +/- 0.002 and 0.041 +/- 0.002 %/mo, respectively). There was a direct breed x forage interaction (P < 0.05) for mature BW. These data suggest that the choice of breed type is important in maintaining a crossbreeding program, in that mature BW and rate of maturing are critical to the matching of animal requirements to available production resources. 相似文献
37.
In a randomized, confirmatory study performed between July and October 2000 the efficacy of two iron products in preventing iron deficiency anaemia was compared. A total of 102 newborn piglets from ten litters were treated intramuscularly with 200 mg iron as iron dextran per ml, or 200 mg iron as gleptoferron per ml. For true comparison, piglets within a litter of a sow were subdivided into pairs on the basis of birth weight (one pair of the two heaviest piglets, et cetera). Within a pair, treatment with the iron supplements was randomly allocated. One group of piglets was injected at an age of 1 day (experiment 1) and the other group of piglets was injected at an age of 3 days (experiment 2). The piglets were weighed and blood samples were taken at an age of 18 days (experiment 1) or at an age of 19 days (experiment 2). Average daily weight gain and haemoglobin concentrations of both treatment groups were compared. Both products were very effective in preventing anaemia. No significant differences could be found between the two formulations. It can be concluded that iron-dextran and gleptoferron can be used with similar effect for anaemia prevention in piglets. 相似文献
38.
Gaustad-Aas AH Ropstad E Karlberg K Hofmo PO Dahl E 《Acta veterinaria Scandinavica》2002,43(3):157-164
Serum from 88 pregnant sows and gilts was sampled 24 and 28 days after their first insemination or mating day. The oestrone sulphate (E1S) concentration in the samples was assessed with a commercially available radioimmunoassay kit modified for use with swine serum. The first aim was to test whether it was possible to predict litters of total number <10 piglets at term. The second aim was to compare the use of day 24 or day 28 samples, or of both, in this prediction. Day 24 E1S levels were positively correlated with litter size at term (R2 = 0.26; p <0.001). E1S levels on day 28 were correlated with the levels on day 24 in the same animals but could not be used for prediction of large or small litters. The odds ratio for a small litter size was 0.16 (p <0.01). This means that odds for a litter size <10 piglets decreased by 84% when E1S levels increased by 1.0 ng/ml. 相似文献
39.
40.
ABSTRACT The effect of temperature on infection of lettuce by Bremia lactucae was investigated in controlled environment studies and in the field. In controlled conditions, lettuce seedlings inoculated with B. lactucae were incubated at 15, 20, 25, or 30 degrees C during a 4-h wet period immediately after inoculation or at the same temperatures during an 8-h dry period after the 4-h postinoculation wet period at 15 degrees C. High temperatures during wet and dry periods reduced subsequent disease incidence. Historical data from field studies in 1991 and 1992, in which days with or without infection had been identified, were analyzed by comparing average air temperatures during 0600 to 1000 and 1000 to 1400 Pacific standard time (PST) between the two groups of days. Days without infection had significantly higher temperatures (mean 21.4 degrees C) than days with infection (20.3 degrees C) during 1000 to 1400 PST (P < 0.01) but not during 0600 to 1000 PST. Therefore, temperature thresholds of 20 and 22 degrees C for the 3-h wet period after sunrise and the subsequent 4-h postpenetration period, respectively, were added to a previously developed disease warning system that predicts infection when morning leaf wetness lasts >/=4 h from 0600 PST. No infection was assumed to occur if average temperature during these periods exceeded the thresholds. Based on nonlinear regression and receiver operating characteristic curve analysis, the leaf wetness threshold of the previous warning system was also modified to >/=3-h leaf wetness (>/=0900 PST). Furthermore, by comparing solar radiation on days with infection and without infection, we determined that high solar radiation during 0500 to 0600 PST in conjunction with leaf wetness ending between 0900 and 1000 PST was associated with downy mildew infection. Therefore, instead of starting at 0600 PST, the calculation of the 3-h morning leaf wetness period was modified to start after sunrise, defined as the hour when measured solar radiation exceeded 8 W m(-2) (or 41 mumol m(-2) s(-1) for photon flux density). The modified warning system was compared with the previously developed system using historical weather and downy mildew data collected in coastal California. The modified system was more conservative when disease potential was high and recommended fewer fungicide applications when conditions were not conducive to downy mildew development. 相似文献