全文获取类型
收费全文 | 1052篇 |
免费 | 53篇 |
专业分类
林业 | 36篇 |
农学 | 35篇 |
基础科学 | 21篇 |
148篇 | |
综合类 | 88篇 |
农作物 | 37篇 |
水产渔业 | 72篇 |
畜牧兽医 | 595篇 |
园艺 | 11篇 |
植物保护 | 62篇 |
出版年
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 25篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 54篇 |
2012年 | 28篇 |
2011年 | 47篇 |
2010年 | 26篇 |
2009年 | 32篇 |
2008年 | 55篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 44篇 |
2004年 | 38篇 |
2003年 | 32篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 14篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1971年 | 11篇 |
1969年 | 11篇 |
1967年 | 8篇 |
排序方式: 共有1105条查询结果,搜索用时 296 毫秒
111.
R Jensen R E Pierson R D Schupbach 《Journal of the American Veterinary Medical Association》1975,167(8):742-745
From a Colorado enterprise annually fattening about 50,000 lambs, 3,664 animals were examined for muscular cysticercosis. Of the total number, 406 (11.1%) were parasitized, wheras an estimated 0.1% of Colorado lamb carcasses are infected. Of the infected lambs, 60% had cardiac lesions. Two types of cysticerci-viable and degenerated-were found. The lambs probably acquired infection from grazing summer ranges and pastures where coyotes or dogs infected with Taenia ovis contaminated the forage. 相似文献
112.
A randomized blocked factorial experiment was conducted with 90 young pigs. From 4 to 11 weeks of age the pigs were kept in individual pens and fed a selenium supplemented basal diet consisting mostly of propionic acid treated barley, soybean meal and dried skim milk, and containing < 0.5 mg vitamin E per kg. The treatment factors during this period were 3 dietary levels of added vitamin E (nil, 10 and 30 mg/kg) and a 6 % supplement of fresh or oxidized fat (2/3 lard and 1/3 herring oil). From 11 weeks of age until slaughter at 90 kg the pigs received the vitamin E supplements but no fat or dried skim milk. The basal diet for this later experimental period was based on untreated dry barley. Blood samples collected during the period of investigation were examined for vitamin E and for resistance against erythrocyte lipid peroxidation (ELP) in order to evaluate the antioxidant status.Analysis of variance and Student’s t-test on least squares means showed the ELP to be influenced independently by the vitamin E supplement and, during the fat feeding period, by the quality of the fat supplement, with the highest peroxidation resistance (low ELP) in the groups fed fresh fat and a high level of vitamin E. Blood vitamin E level was only influenced — positively — by the vitamin E supplement although variations in the feed vitamin E level below 10–15 mg vitamin E per kg did not result in corresponding variations in measurable blood vitamin E concentrations. In the same low range of vitamin E in the feed there was a statistically significant difference in ELP values between the different vitamin E treatment groups. No clinical manifestations of selenium-vitamin E deficiency were observed in the pigs.The ELP and the plasma vitamin E levels observed would seem to suggest that a total of 15 mg vitamin E per kg barley-based feed will not always be sufficient for growing pigs. 相似文献
113.
Mycosis in the stomach compartments of cattle 总被引:1,自引:0,他引:1
During a period of 22 months, 9.7% (23 out of 238) of the cattle necropsied at the Department of Veterinary Pathology had mycotic affections in the stomach compartments. The various stomach compartments were affected in the following pattern: omasum: 15 cases, rumen: 10 cases, reticulum: 8 cases and abomasum: 6 cases. In 5 of the animals mycotic affection was also found in other organs of which the liver was most often involved. Out of the 23 cases described, a primary diagnosis of mycosis was only established in 5 cases. In the remaining 18 cases the mycotic infection was regarded as being of a minor importance in the total necropsy result. Macroscopically and histologically the mycotic processes could be grouped into acute, subacute or chronic affections. In 20 cases only one type of inflammation was present, in the remaining cases combinations were found. Identification of the infective agent was performed by immunological staining of hyphal structures in tissue sections. Members of the Zygomycetes were found to predominate as causative fungi. Aspergillus fumigatus was found to have a propensity for infecting the terminal gastric compartments, whereas the Zygomycetes were found regularly in all compartments. Candida spp. were only found in 1 case. Predisposing factors for developing systemic mycosis are discussed. Among these especially the use of antimicrobial drugs, other diseases, metabolic disturbances and stressors in the post parturient period seem to be important. 相似文献
114.
T Mattila J Syv?j?rvi N E Jensen M Sandholm 《American journal of veterinary research》1986,47(1):139-142
Interrelationships between N-acetyl-beta-D-glucosaminidase (indicating cellular damage) and antitrypsin (indicating increased permeability between the blood and milk compartments) were evaluated in 1,411 quarter-milk samples collected during routine herd surveys. N-Acetyl-beta-D-glucosaminidase was antitrypsin, whereas, in more severe mastitis, antitrypsin had a more constant deflection. The sensitivity of both determinants was associated with the virulence of bacteria. Production of bacterial hemolytic toxins was associated with a significant increase in both determinants. Penicillinase production by staphylococci was associated with selective increases of antitrypsin. 相似文献
115.
K Jensen 《Acta veterinaria Scandinavica》1974,15(3):445-447
116.
117.
A. L. Jensen 《Veterinary research communications》1993,17(1):13-23
Fructosamines are formed when glucose reacts non-enzymatically with amino groups on proteins, and previous studies have indicated that the serum fructosamine concentration could be of importance in the diagnosis of canine diabetes mellitus. Owing to the connection between the protein/albumin concentration and serum fructosamine concentration, it has been suggested that the serum fructosamine concentration should be corrected for the protein/albumin concentration. Thus, the purpose of the present study was to evaluate the uncorrected serum fructosamine concentration and various protein and albumin corrections of the serum fructosamine concentration in the separation of dogs with diabetes mellitus from dogs with other diseases that presented with clinical signs suggestive of diabetes mellitus. The evaluation was assisted by relative operating characteristic curves (ROC curves), which may be used to compare various diagnostic tests under equivalent conditions (equal true positive ratios or false positive ratios) and over the entire range of cutoff values. A total of 58 dogs (15 dogs with diabetes mellitus and 43 dogs with other diseases) were included in the study. Serum fructosamine concentration, serum total protein concentration and serum albumin concentration were measured in each dog, and various corrections of the serum fructosamine concentration for protein or albumin concentration were made. Comparing the ROC curves of the uncorrected and each corrected serum fructosamine concentration indicated that there was no decisive difference between the uncorrected and the corrected serum fructosamine concentrations in discriminating between dogs with and without diabetes mellitus. Hence, correcting the serum fructosamine concentration as a routine procedure cannot be advocated from the results of the study. Moreover, the sensitivity and specificity of the uncorrected serum fructosamine concentration were very high, 0.93 and 0.95, respectively, further evidence of the value of the uncorrected serum fructosamine concentration in the diagnosis of canine diabetes mellitus.Abbreviations SFC
serum fructosamine concentration
- SFC-P
serum fructosamine concentration corrected for the actual serum total protein concentration
- SFC-A
serum fructosamine concentration corrected for the actual serum albumin concentration
- SFC-Po
serum fructosamine concentration corrected for the actual serum total protein concentration, only when the serum total protein concentration is outside the reference interval
- SFC-Ao
serum fructosamine concentration corrected for the actual serum albumin concentration, only when the serum albumin concentration is outside the reference interval
- SFC-K
serum fructosamine concentration corrected according to Kawamotoet al. (1992) 相似文献
118.
G Bolt J Monrad P Henriksen H H Dietz J Koch E Bindseil A L Jensen 《Acta veterinaria Scandinavica》1992,33(4):357-362
Until recently, Angiostrongylus vasorum was not considered to be an endogenous Danish parasite, since demonstration of this worm had been confined to necropsy findings in 2 dogs, both of which had visited France. During the last 2 years, however, clinical cases have been diagnosed among a considerable number of Danish dogs, none of which had ever been outside Denmark. All these cases have occurred north of Copenhagen, where an endemic focus seems to exist. In this field survey A. vasorum was found for the first time in wild Danish red foxes. Furthermore, experimental infections showed that the parasite can be transferred between foxes and dogs. Consequently, the wild fox population must be considered a potential reservoir for transfer of A. vasorum to domestic dogs. 相似文献
119.
Residual energy intake, defined as actual minus predicted energy intake during a production period, was estimated for each of 650 bull calves of 31 Holstein Friesian or Brown Swiss sires. Residual energy intake, measured under ad libitum feeding, had heritabilities similar to those of growth rate and energy conversion ratio with an estimate of approximately .3. Residual energy intake was related to average daily energy intake both phenotypically and genetically such that selection for decreased residual energy intake would lead to a decrease in daily feed intake. Such selection would also tend to increase carcass fatness (i.e., genetically fat animals are the most efficient). Residual energy intake estimated with and without correction for carcass composition were closely correlated. Thus, residual energy intake may be estimated without the knowledge of carcass composition in growing bulls of dual-purpose breeds. 相似文献
120.
Niels Einar Jensen 《Acta veterinaria Scandinavica》1980,21(3):354
During a 3-year period strains of Group-B streptococci from 1227 (94.6 %) of a total of 1297 cases of bovine mastitis were serologically typed. Twenty-seven different antigenic combinations were found. Ab. 70 % of the strains carried polysaccharide antigens among which Type III was predominant (57 %). The protein antigen X was widespread (62 %), and 5 % of the strains were non-type able.Type Ic predominated among “false positive” bulk milk isolates (52.2 %, 12/23), but was rarely isolated from quarter milk samples (3%).Variation in the antigenic structure of infecting strains occurred to some extent and involved at least 10.8 % (132/1227) and probably 25.2 % (132/523) of the strains. Within a herd the antigenic variation was limited, however. Hence a definition of a herd type was possible. During the period of investigation infections caused by Herd Type III decreased numerically while the number of herds infected by other types remained almost stable. 相似文献