首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   224篇
  免费   27篇
林业   16篇
农学   2篇
  35篇
综合类   17篇
农作物   12篇
水产渔业   25篇
畜牧兽医   114篇
园艺   10篇
植物保护   20篇
  2023年   2篇
  2022年   6篇
  2021年   4篇
  2020年   4篇
  2019年   13篇
  2018年   6篇
  2017年   9篇
  2016年   10篇
  2015年   7篇
  2014年   6篇
  2013年   6篇
  2012年   12篇
  2011年   20篇
  2010年   10篇
  2009年   14篇
  2008年   13篇
  2007年   14篇
  2006年   10篇
  2005年   7篇
  2004年   11篇
  2003年   8篇
  2002年   6篇
  2001年   5篇
  2000年   2篇
  1999年   1篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1993年   2篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1982年   2篇
  1980年   3篇
  1979年   2篇
  1978年   3篇
  1977年   5篇
  1968年   2篇
  1967年   2篇
  1966年   3篇
  1959年   1篇
  1958年   1篇
  1945年   1篇
  1898年   1篇
排序方式: 共有251条查询结果,搜索用时 203 毫秒
81.
There are a few investigations into endometritis in the bitch and its relationship with failure to conceive remains unclear. This may be because of the difficulty in collecting uterine samples for further investigations. Recently, transcervical catheterization by vaginal endoscopy has been introduced allowing the evaluation of the endometrium. In this study, uterine cytology and bacteriology were evaluated in 26 infertile bitches. Endometritis was bacterial in origin in most cases (70% of affected bitches), but these results may be underestimated, as some other pathogens (anaerobic bacteria, mycoplasms and fungi) were not investigated. Endometritis, in our opinion, should be investigated in each case of unexplained infertility in bitches. The method used here seems reliable although defining more accurate classification criteria will improve the efficiency of this non-invasive technique.  相似文献   
82.
Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is an organophosphorus insecticide applied to soil to control pests both in agricultural and in urban developments. Typical agricultural soil applications (0.56 to 5.6 kg ha?1) result in initial soil surface residues of 0.3 to 32 μg g?1. In contrast, termiticidal soil barrier treatments, a common urban use pattern, often result in initial soil residues of 1000 μg g?1 or greater. The purpose of the present investigation was to understand better the degradation of chlorpyrifos in soil at termiticidal application rates and factors affecting its behaviour. Therefore, studies with [14C]chlorpyrifos were conducted under a variety of conditions in the laboratory. Initially, the degradation of chlorpyrifos at 1000 μg g?1 initial concentration was examined in five different soils from termite-infested regions (Arizona, Florida, Hawaii, Texas) under standard conditions (25°C, field moisture capacity, darkness). Degradation half-lives in these soils ranged from 175 to 1576 days. The major metabolite formed in chlorpyrifos-treated soils was 3,5,6-trichloro-2-pyrid-inol, which represented up to 61% of applied radiocarbon after 13 months of incubation. Minor quantities of [14C]carbon dioxide (< 5%) and soil-bound residues (? 12%) were also present at that time. Subsequently, a factorial experiment examining chlorpyrifos degradation as affected by initial concentration (10, 100, 1000 μg g?1), soil moisture (field moisture capacity, 1.5 MPa, air dry), and temperature 15, 25, 35°C) was conducted in the two soils which had displayed the most (Texas) and least (Florida) rapid rates of degradation. Chlorpyrifos degradation was significantly retarded at the 1000 μg g?1 rate as compared to the 10 μg g?1 rate. Temperature also had a dramatic effect on degradation rate, which approximately doubled with each 10°C increase in temperature. Results suggest that the extended (3–24 + years) termiticidal efficacy of chlorpyrifos observed in the field may be due both to the high initial concentrations employed (termite LC 50 = 0.2– 2 μg g?1) and the extended persistence which results from employment of these rates. The study also highlights the importance of investigating the behaviour of a pesticide under the diversity of agricultural and urban use scenarios in which it is employed.  相似文献   
83.
84.
Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. During larval development, a specific immune reaction is initiated by the host with a humoral local and systemic response and the recruitment of eosinophils and mast cells in the upper airways mucosae. Nevertheless, the roles of these responses in the regulation of O. ovis larvae populations in sheep are not yet known. The aim of this study was to compare the establishment and the development of larvae as well as some inflammatory or immune parameters between different groups of half-sibling sheep: (i) a primed group experimentally infected twice before a challenge infection, (ii and iii) two groups infected once only and previously treated with a long-lasting cortico?d before the challenge (one group) or not (the other group). A fourth group of non-infected animals was added in the experimental design. The larval establishment rate was 23% in the cortico?d treated group compared to about 10% in the two other infected groups. Moreover, the larval development appeared more rapid in the cortico?d treated group than in the two other infected groups suggesting that the inflammatory response is involved in the regulation of O. ovis populations. By contrast, no differences in the establishment rates were shown in the primed group compared to the na?ve group (without cortico?d treatment) despite evidence of higher eosinophilia, serum specific IgG, and immediate hypersensibility to excretory-secretory products of larvae. The specific lymphocyte proliferation was reduced in the primed group compared to the na?ve one suggesting that an immuno-suppression occurs following repetitive O. ovis infections.  相似文献   
85.
An 8-year-old intact male cat was presented with a subcutaneous mass in the region of the right jugular vein. Cytologic and histopathologic examinations revealed cells with multilobulated nuclei (flower cells). Immunochemistry using a panel of markers showed vimentin-positivity on cytologic specimens, and postive staining for CD79a and BLA36 on histologic specimens. The final diagnosis was lymphoma of B-cell origin. We have observed similar multilobulated cells in ascites fluid, thoracic fluid, and peripheral blood from dogs and cats with a variety of lymphoid and myeloid neoplasms. Cells with multilobulated nuclei that resemble flower petals also have been described in humans. These cells are infrequently observed in canine and feline cytology specimens and require immunochemistry to determine their cell of origin.  相似文献   
86.
Listeria monocytogenes is a foodborne pathogen of major concern for public health in industrialised countries. Since L. monocytogenes carriage by pigs at the herd level could be a primary source for carcass contamination, control measures should be designed to reduce the L. monocytogenes load at the pre-harvest stage. For this purpose, an exploratory analytical survey was carried out in 2000-2001 in 93 French farrow-to-finish pig farms concerning L. monocytogenes contamination in pigs before they left for the slaughterhouse. On each farm, the L. monocytogenes status of a batch of contemporary fattening pigs housed in the same room was assessed on faecal material samples taken by means of gauze swabs wiped on the perianal region of the pigs. Fourteen percent of the batches studied had at least one contaminated sample and were therefore classified as L. monocytogenes contaminated batches. Two logistic regression models were used to assess the association between managerial and hygiene practices and the risk of L. monocytogenes contamination of the batch at the end of the finishing period on the whole data set (n = 93) and in the wet feeding farms only (n = 57). Wet feeding during the fattening period was identified as a risk factor for L. monocytogenes contamination. Risk factors related to the introduction of L. monocytogenes in pig facilities were identified for both the general and wet feeding farm data sets. Poor care paid to hygiene on the farms was found to increase the risk of being infected (boots cleaning, change room presence). When the duration of the empty period prior to the introduction of growing pigs was less than one day in the fattening section, the risk of L. monocytogenes contamination was significantly increased. For wet feeding farms, a distribution pipeline cleaning procedure including disinfection was found to be associated with a higher risk of contamination than no cleaning or a procedure consisting of rinsing with water only.  相似文献   
87.
Facial dermatitis in cats is a poorly understood clinical problem observed in Persian and Himalayan cats. This report describes three cases of idiopathic facial dermatitis in the Persian cat controlled with cyclosporine. The syndrome was observed in a 5‐year‐old intact female, a 1.5‐year‐old intact male, and a 3‐year‐old neutered male Persian cat. The lesions developed over 2 years, 2 months and 18 months, respectively. Cutaneous lesions were mainly localized to the face. A black patchy waxy exudate matted the hair, especially on the chin. Mild crusts and black exudate were also noted on the vulvar folds in one case and on the ventral aspect of the neck in another case. Erythematous, ceruminous otitis was observed in one case. The histopathological findings were exactly the same for all three cases and compatible with idiopathic facial dermatitis of the Persian cat, or eventually an allergic reaction. All cases were managed with cyclosporine (Neoral® 6–7 mg/kg/day). Lesions were completely controlled after 4–6 weeks. During a 6‐month follow‐up for two cases, the lesions seemed to be more resistant to therapy. For these two cats, secondary infections with cocci and Malassezia occasionally occurred. No adverse reactions were observed in our three treated cats. Funding: Self‐funded.  相似文献   
88.
89.
OBJECTIVE: To evaluate efficacy of cyclosporine A, administered at either of 2 dosages, in dogs with atopic dermatitis (AD). DESIGN: Multicenter randomized controlled trial. ANIMALS: 91 dogs with AD. PROCEDURE: Dogs were assigned to receive placebo (30 dogs), cyclosporine at a low dosage (2.5 mg/kg [1.1 mg/lb], PO, q 24 h for 6 weeks; 30 dogs), or cyclosporine at a high dosage (5.0 mg/kg [2.3 mg/lb], PO, q 24 h for 6 weeks; 31 dogs). RESULTS: After 6 weeks, mean percentage reductions, compared with baseline scores, in scores of lesion severity were 34, 41, and 67% for dogs treated with the placebo, cyclosporine at the low dosage, and cyclosporine at the high dosage, respectively. Similarly, mean percentage reductions in pruritus scores were 15, 31, and 45%, respectively. Percentage reductions in skin lesion and pruritus scores were significantly higher for dogs given cyclosporine at the high dosage than for dogs given the placebo. Treatment efficacy was significantly associated with whether dogs had a history of seasonal AD. Percentage reductions in skin lesion and pruritus scores were high for dogs treated with cyclosporine at the highest dosage that had a history of nonseasonal AD. Dogs in all groups with seasonal AD improved during the study period. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that oral administration of cyclosporine at a dosage of 5.0 mg/kg once daily is effective in reducing severity of pruritus and skin lesions in dogs with AD, especially those with nonseasonal disease.  相似文献   
90.
Twelve monoclonal antibodies (MAbs) were obtained by immunizing mice with a French isolate (F1) of wheat yellow mosaic virus (WYMV). Three of these (3D12, 2C1, 6C3) belong to the IgM class and the nine others to the IgG class (3D8, 3H1, 2B8, 1F2, 3C10, 4F12, 3H9, 1G5, 54). In antigen-coated plate (ACP) ELISA and indirect double antibody sandwich (IDAS) ELISA, all MAbs recognize the WYMV (F1) both in the form of purified particles and in wheat leaf extract. The analysis of numerous French isolates of WYMV shows a variable reactivity with MAbs 3D8, 3H1, 2B8, 3C10, 3H9 and 1G5 in IDAS — and ACP-ELISA. The Japanese isolate of WYMV and United States isolates of wheat spindle streak mosaic virus (WSSMV) were detected in IDAS- and ACP-ELISA by ten of the MAbs tested showing that the wheat bymoviruses originating from the three locations share a high epitopic homology. French isolates of barley yellow mosaic virus (BaYMV; pathotypes 1 and 2) were only detected in ACP-ELISA with MAbs 6C3, 3D8, 3H1 and 2B8 whereas the two Japanese strains (I-1, II-1) of MaYMV were recognized with these and also with that of 3C10. In IDAS-ELISA, the two Japanese strains were clearly detected by MAbs, 6C3, 3D8, 3H1, 1F2, 3C10 and 1G5 and the British and Belgian (pathotype 2) isolates only by that of 6C3. Only the Japanese strain of BaYMV, 1-1 could be detected with MAb 3H9 in this ELISA system.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号