全文获取类型
收费全文 | 19400篇 |
免费 | 145篇 |
国内免费 | 140篇 |
专业分类
林业 | 831篇 |
农学 | 266篇 |
基础科学 | 189篇 |
2387篇 | |
综合类 | 4849篇 |
农作物 | 593篇 |
水产渔业 | 270篇 |
畜牧兽医 | 9491篇 |
园艺 | 221篇 |
植物保护 | 588篇 |
出版年
2022年 | 60篇 |
2021年 | 55篇 |
2019年 | 53篇 |
2018年 | 62篇 |
2015年 | 66篇 |
2014年 | 139篇 |
2013年 | 117篇 |
2012年 | 1486篇 |
2011年 | 1748篇 |
2010年 | 375篇 |
2009年 | 236篇 |
2008年 | 1379篇 |
2007年 | 1475篇 |
2006年 | 1405篇 |
2005年 | 1272篇 |
2004年 | 1172篇 |
2003年 | 1161篇 |
2002年 | 1033篇 |
2001年 | 749篇 |
2000年 | 929篇 |
1999年 | 426篇 |
1998年 | 87篇 |
1997年 | 90篇 |
1996年 | 71篇 |
1995年 | 100篇 |
1994年 | 113篇 |
1993年 | 151篇 |
1992年 | 142篇 |
1991年 | 129篇 |
1990年 | 122篇 |
1989年 | 121篇 |
1988年 | 135篇 |
1987年 | 149篇 |
1986年 | 130篇 |
1985年 | 120篇 |
1984年 | 154篇 |
1983年 | 109篇 |
1982年 | 101篇 |
1981年 | 86篇 |
1980年 | 85篇 |
1979年 | 47篇 |
1975年 | 50篇 |
1974年 | 50篇 |
1963年 | 58篇 |
1960年 | 50篇 |
1958年 | 64篇 |
1957年 | 47篇 |
1956年 | 46篇 |
1955年 | 48篇 |
1954年 | 46篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Swinepox--skin disease with sporadic occurrence 总被引:1,自引:0,他引:1
Moorkamp L Beineke A Kaim U Diesterbeck U Urstadt S Czerny CP Rüberg H Grosse Beilage E 《DTW. Deutsche tier?rztliche Wochenschrift》2008,115(4):162-166
Swinepox virus infection results in an acute, mild or subclinical course and is characterised by typical poxvirus skin lesions in affected pigs. Additionally, sporadic vertical swinepox virus transmission leads to congenital generalised infection and subsequent abortion or stillbirth. The present report describes the occurrence of epidermal efflorescences in two piglets after intrauterine natural suipoxvirus infection. No clinical abnormalities of the gilt and littermates as well as in other pigs from this herd were present. One of the affected piglets was stillborn and submitted for necropsy, the other animal was alive at birth, but died 3 days later. Histologically, a proliferative to ulcerative dermatitis with epithelial ballooning degeneration and characteristic intracytoplasmatic inclusion bodies was observed. The pathomorphological and histopathological suspected diagnosis of a poxvirus infection was confirmed by electron microscopy. Furthermore, the agent was identified as suipoxvirus by polymerase chain reaction. As demonstrated here, obvious skin lesions in suipoxvirus infection leads to a suspected diagnosis in newborn piglets on macroscopic examination. However, further post mortem examinations, including electron microscopy as well as molecular techniques are essential for the identification of the aetiology and the exclusion of differential diagnoses. Because the disease only affected two pigs there was only a small economic loss. A valid diagnostic plays an important role in advising farmers and for herd health monitoring. 相似文献
72.
Ohmi A Tsukamoto A Ohno K Uchida K Nishimura R Fukushima K Takahashi M Nakashima K Fujino Y Tsujimoto H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(1):59-64
Medical records of dogs with colorectal polyps were retrospectively reviewed, and clinical presentation of inflammatory colorectal polyps in miniature dachshunds was evaluated. Of 33 dogs found to have colorectal polyps, miniature dachshunds were markedly over-represented with 16 dogs (48%), of which 12 (75%) were found to have inflammatory polyps. Multiple polyps localized between the rectum and the descending colon was the most common finding in miniature dachshunds with inflammatory polyps. Twenty dogs (80%) out of 25 miniature dachshunds with inflammatory colorectal polyps responded to immunosuppressive therapy using prednisolone and cyclosporine. The results of this study indicate that miniature dachshunds are predisposed to develop inflammatory colorectal multiple polyps, for which immunosuppressive therapy may be a treatment option. 相似文献
73.
The graft-versus-host reaction (GVHR) was demonstrated in a salmonid model system of clonal diploid and triploid amago salmon. Triploid operculum grafts on clonal diploid evoked an acute rejection within 12 days. Grafts exchanged among triploid amago salmon exhibited prolonged survival for 18 days. In contrast, diploid grafts on triploid, and allografts among clonal diploid amago salmon were accepted. A typical GVHR was induced in triploid recipients by intraperitonal injection of head kidney cells from sensitised diploid donors. The clinical signs of graft-versus-host disease (GVHD) were observed in the recipients after 1 week of cell injection as a loss of appetite and appearance of solid faeces, followed by haemorrhage, local swelling of ventral skin and an enlarged spleen. Three of six fish died within 1 month. Water temperature and frequency of sensitisation are critical to induce GVHR. Diploid donors had to be sensitised three times at 20 degrees C to induce the typical GVHR. GVHR was most effectively induced by head kidney cells, followed by peripheral blood leucocytes (PBL) and spleen cells. Ploidy analysis by flow cytometry revealed that the donor head kidney cells greatly increased in the recipient liver, head kidney and spleen, and reached the peak after 9 days of donor cell injection. The results in the present study are quite similar to the findings in ginbuna and ginbuna-gold fish hybrid system, suggesting the presence of T cells in salmonid as well as cyprinid fish. 相似文献
74.
为研究甘南地区欧拉羊杂交改良山谷型藏羊效果,对欧拉羊与山谷型藏羊杂交试验组和山谷型藏羊本交对照组所产后代的初生、3月龄、6月龄、12月龄、18月龄的体尺、体重进行了跟踪测定,并对不同年龄段杂交后代与对照组后代进行了对比分析和差异显著性检验。结果表明:杂交F1代初生、3月龄、6月龄、12月龄、18月龄的体尺、体重极显著的高于对照组(P〈0.01),初生、18月龄管围差异显著,3月龄、6月龄、12月龄管围差异不显著(P〉0.05)。 相似文献
75.
Dalimi A Motamedi G Hosseini M Mohammadian B Malaki H Ghamari Z Ghaffari Far F 《Veterinary parasitology》2002,105(2):161-171
In the present study, 115 stray dogs (56 males and 59 females, mixed breed), 86 golden jackal (Canis aureus, 42 males and 44 females), 60 red foxes (Vulpes vulpes, 33 males and 27 females), and three female wolves (Canis lupus) were examined for Echinococcus granulosus infection, as well as, 32,898 sheep, 10,691 goats, 15,779 cattle and 659 buffaloes for hydatid infection from five provinces in western Iran during 3 years (1997-2000). Meanwhile fertility rates of different types and forms of cysts isolated from infected animals and the viability of protoscolices were also determined. Results indicated that 19.1% of the dogs, 2.3% of the golden jackals and 5% of the red foxes were infected with Echinococcus granulosus. 11.1% of the sheep, 6.3% of the goats, 16.4% of the cattle and 12.4% of the buffaloes were also found to be infected with hydatid cyst. The cysts isolated from liver and lungs of the sheep show higher fertility rate than the cysts of liver and lungs of goats, cattle and buffaloes. 相似文献
76.
77.
Eighty-one isolates presumptively identified as Pasteurella multocida from a variety of diseases in animals in Zimbabwe were subjected to biochemical characterization, capsular typing and RAPD analysis. The majority of isolates (over 80%) were assigned into named taxa and were predominantly P. multocida subsp. multocida and P. multocida subsp. septica, whilst the remainder were unassigned. Serogroup A was predominant among the three capsular types (A, B and D) of P. multocida detected. Three main RAPD clusters and three subclusters were observed among the majority of isolates (93.8%), whilst the remainder was found to be weakly related. Nine different groups of strains with similar RAPD profiles (100% similarity) were also observed. The reference strain of capsular serogroup F clustered with the reference strain of P. multocida subsp. septica, whilst all other serogroups clustered with reference strains of subsp. multocida and gallicida. Notably, serogroups A and D were observed to be closely related to the reference strain of subsp. multocida. The relationship between biotype, capsular type, host origin and disease manifestation was not clear-cut. However, most pig isolates of subsp. multocida clustered together as did most cattle isolates of subsp. multocida. RAPD tended to separate subsp. multocida from septica. 相似文献
78.
Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain 总被引:1,自引:0,他引:1
Rusbridge C Carruthers H Dubé MP Holmes M Jeffery ND 《The Journal of small animal practice》2007,48(8):432-436
OBJECTIVES: This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is dependent upon size and involvement of the dorsal part of the spinal cord. METHODS: Masked observers determined syrinx dimensions and precise location within the spinal cord on magnetic resonance images of 55 cavalier King Charles spaniels with syringomyelia. After removal of masking, syrinx size and location were compared between the cohorts of dogs that exhibited pain with those that did not. RESULTS: Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord. CLINICAL SIGNIFICANCE: Large syrinxes associated with damage to the dorsal part of the spinal cord are associated with persistent pain suggesting that the pain behaviour expressed by this group of patients is likely to be "neuropathic pain," resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective. 相似文献
79.
ABSTRACT Monilinia vaccinii-corymbosi infects open blueberry flowers via the gynoecial pathway, leading to mummification of the developing fruit. To determine the effect of flower age on infection, stigmata were inoculated with conidia of M. vaccinii-corymbosi between 0 and 5 days after anthesis, fungal growth rates through the stylar canal were measured in detached flowers in the laboratory, and fruit disease incidence was determined in plants grown in the greenhouse. Hyphal growth rates were greatest in flowers inoculated on the day of anthesis, declined linearly with increasing flower age at inoculation (r = 0.921; P < 0.0001; n = 12), and were unaffected by the presence or absence of pollen applied at the time of inoculation. In greenhouse-grown plants, the percentage of infected fruit decreased exponentially with increasing flower age at inoculation (R = 0.878; P = 0.0057; n = 10), with disease incidence ranging from 76.4% for flowers inoculated on the day of anthesis to 15.5% for those inoculated 4 days later. Fruit disease incidence in the greenhouse was linearly correlated with hyphal growth rates in detached flowers (r = 0.985; P < 0.0001; n = 9), justifying the use of detached flowers when investigating gynoecial infection by M. vaccinii-corymbosi. In separate experiments, the effects of timing and sequence of pollination and inoculation on hyphal growth rates through the stylar canal and on disease incidence were investigated. Application of pollen to detached flowers 1 or 2 days before inoculation reduced hyphal growth rates by between 14.0 and 42.9% compared with flowers that received pollen and conidia simultaneously. Similarly, reductions in fruit disease incidence by between 9.5 and 18.3% were observed on greenhouse-grown plants for pollination-to-inoculation intervals ranging from 1 to 4 days. These results document that newly opened flowers are most susceptible to infection by M. vaccinii-corymbosi and that fruit disease incidence is reduced if pollination occurs at least 1 day before inoculation. Strategies that lead to early pollination of newly opened flowers may be useful for managing mummy berry disease in the field. 相似文献
80.
Eight dogs with generalized demodicosis and five with sarcoptic mange were treated with 1.25% amitraz solution applied weekly and associated with an antidote treatment (atipamezol, 0.1 mg kg−1 IM once: and yohimbine 0.1 mg kg−1 once daily for 3 days, orally). Results of skin scrapings were used to determine whether therapy should be continued or stopped. The median number of treatments for demodicosis and sarcoptic mange was three (range 2–5) and two (range 1–3), respectively. Some side-effects were observed but all were stopped with antidote treatment; no failure or relapses occurred at 6–36 months after treatment. 相似文献