全文获取类型
收费全文 | 475篇 |
免费 | 45篇 |
专业分类
林业 | 40篇 |
农学 | 16篇 |
基础科学 | 7篇 |
103篇 | |
综合类 | 29篇 |
农作物 | 21篇 |
水产渔业 | 38篇 |
畜牧兽医 | 196篇 |
园艺 | 20篇 |
植物保护 | 50篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 24篇 |
2012年 | 25篇 |
2011年 | 44篇 |
2010年 | 27篇 |
2009年 | 20篇 |
2008年 | 34篇 |
2007年 | 26篇 |
2006年 | 23篇 |
2005年 | 19篇 |
2004年 | 29篇 |
2003年 | 24篇 |
2002年 | 29篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1980年 | 1篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1971年 | 1篇 |
1964年 | 2篇 |
1962年 | 1篇 |
1961年 | 2篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1885年 | 1篇 |
排序方式: 共有520条查询结果,搜索用时 31 毫秒
41.
Effects of garlic powders with varying alliin contents on hepatic drug metabolizing enzymes in rats 总被引:3,自引:0,他引:3
Le Bon AM Vernevaut MF Guenot L Kahane R Auger J Arnault I Haffner T Siess MH 《Journal of agricultural and food chemistry》2003,51(26):7617-7623
The anticarcinogenic effect of garlic has been demonstrated in both epidemiologic and experimental studies. In this study, possible mechanisms involved in the anticarcinogenic effect of garlic consumption were assessed by determining its capacity to alter drug metabolizing enzymes, in relation with its alliin content. Rats were fed a diet for 2 weeks containing 5% garlic powders produced from bulbs grown on soils with different levels of sulfate fertilization and therefore containing differing amounts of alliin. Activities of several hepatic enzymes, which are important in carcinogen metabolism such cytochromes P450 (CYP) and phase II enzymes, were determined. Garlic consumption slightly increased ethoxyresorufin O-deethylase and CYP 1A2 levels. In contrast, garlic consumption decreased CYP 2E1 activity and the level of the corresponding isoform. UDP glucuronosyl transferase and glutathion S-transferase activities were increased by garlic powders. The alliin content of the garlic powders was positively correlated with UGT activity although not with other activities. Effects produced by garlic consumption were qualitatively similar to that of diallyl disulfide, a sulfur compound that has been extensively studied. These data could partially explain the chemoprotective effect of garlic. 相似文献
42.
Adherence of Actinobacillus pleuropneumoniae to porcine tracheal epithelial cells and frozen lung sections 总被引:3,自引:0,他引:3
The ability of 23 different Actinobacillus pleuropneumoniae isolates to adhere in vitro to porcine tracheal epithelial cells and to porcine frozen lung sections was examined. It was found that A. pleuropneumoniae adhered poorly to isolated tracheal epithelial cells. On the other hand, A. pleuropneumoniae adhered to frozen lung sections and marked variations were observed between and within serotypes. Adherence to lung sections did not seem related to the hemagglutinating activity of the isolate. Two noncapsulated variants adhered to lung sections in greater numbers than their capsulated parent strains. Adherence to lung sections was not inhibited by the extracellular matrix components tested namely, laminin, fibronectin, and collagen, but was inhibited by homologous serotype-specific antiserum. The data indicated that the A. pleuropneumoniae isolates tested possess the ability to adhere to porcine lung tissue, a property which did not seem to be related to the serotype and did not seem to involve the capsular material or the hemagglutinins of the isolates. 相似文献
43.
Characterization of Serpulina hyodysenteriae isolates of serotypes 8 and 9 from Quebec by restriction endonuclease fingerprinting and ribotyping. 下载免费PDF全文
This study was undertaken to assess the discriminatory value of restriction endonuclease fingerprinting (REF) analysis and ribotyping of 21 Serpulina hyodysenteriae isolates of serotypes 8 and 9. For REF analysis, DNAs were digested with the BglII restriction enzyme and the resultant fragments were separated by polyacrylamide gel electrophoresis. For ribotyping, hybridization of BglII genomic fragments with a probe of rrnB operon using an Escherichia coli rDNA probe was performed on all isolates. Although many isolates shared a common pattern by BglII REF and BglII ribotyping analysis, differences among some S. hyodysenteriae isolates were observed. REF and ribotyping using BglII restriction enzyme, were not specific for serotypes. The predominance of an REF and a ribotype pattern among S. hyodysenteriae isolates from Quebec suggested that epidemiologically important S. hyodysenteriae types occur in different swine herds. 相似文献
44.
Natural infection with an attaching and effacing Escherichia coli in a diarrheic puppy. 总被引:4,自引:0,他引:4 下载免费PDF全文
A Broes R Drolet M Jacques J M Fairbrother W M Johnson 《Canadian journal of veterinary research》1988,52(2):280-282
Enteric infection with an attaching and effacing Escherichia coli was diagnosed in a puppy with protracted diarrhea. Extensive colonization of the small intestinal mucosa was observed by light and scanning electron microscopy and characteristic lesions of bacterial attachment of the brush border of the enterocytes were demonstrated by transmission electron microscopy. The E. coli strain isolated from the small intestine belonged to serotype O49:H10, did not produce any known E. coli enterotoxin or cytotoxin, was not invasive, and was negative for the known fimbrial colonization factors produced by animal and human enterotoxigenic E. coli. A positive immunoperoxidase reaction was obtained on the bacteria attached to the enterocytes with an anti-E. coli O49 antiserum. 相似文献
45.
水产动物对维生素C和维生素E的营养需求 总被引:4,自引:0,他引:4
本文综述了水产动物中维生素C和维生素E的生理功能、缺乏症、营养需求、剂型选择等,并对最佳维生素营养(0VN)作了简要介绍。 相似文献
46.
Adherence of Bordetella bronchiseptica and Pasteurella multocida to porcine nasal and tracheal epithelial cells. 总被引:4,自引:1,他引:3 下载免费PDF全文
The ability of 19 different Bordetella bronchiseptica isolates and 25 Pasteurella multocida isolates to adhere in vitro to porcine nasal and tracheal epithelial cells was examined. It was found that B. bronchiseptica adhered well to upper respiratory tract cells. In contrast the number of P. multocida organisms which adhered was four to six times less than the number of B. bronchiseptica adherent organisms. This difference was statistically significant (p less than 0.0001). Both microorganisms adhered in greater numbers to nasal cells than to tracheal cells (p less than 0.005). The data indicated that B. bronchiseptica possesses a greater ability than P. multocida to attach to porcine upper respiratory tract cells. 相似文献
47.
Dacasto M Eeckhoutte C Capolongoa F Dupuy J Carletti M Calléja C Nebbia C Alvinerie M Galtier P 《Veterinary research》2005,36(2):179-190
The cytochrome P450 (P450) superfamily represents a group of relevant enzymes in the field of drug metabolism and several exogenous or constitutional factors contribute to regulate its expression. Cattle represent an important source of animal-derived food-products and studies concerning the P450 expression are needed for the extrapolation of pharmacotoxicological data from one species to another and for the evaluation of the consumer's risk associated with the consumption of harmful residues found in foodstuffs. In the present study, possible breed-, gender- and species-differences in P4503A (the P450 subfamily more expressed in the human liver) expression were studied in vitro in Piedmontese (PDM) and Limousin (LIM) meat cattle breeds of both sexes and in domestic Ruminants (cattle, sheep and goats). Cytochrome P450 and P4503A contents as well as CYP3A-dependent drug metabolising enzymes (DME) were measured in liver microsomes. Significant lower levels of P450 (P < 0.001) and P4503A (P < 0.05) contents were observed in PDM vs. LIM of both sexes; the P4503A-dependent DME activities were significantly (P values ranging from 0.05 up to 0.001) higher in PDM cattle, particularly in males. A gender-effect in DME activities was noticed (P < 0.05) only in PDM male cattle. With regards to the species, the expression of both P4503A apoprotein and some of the related DME activities were more pronounced in sheep (P < 0.01 vs. cattle) and in goats (P < 0.05 vs. sheep; P < 0.01 vs. cattle) than in cattle. The significant differences in P4503A expression observed in LIM and PDM cattle are consistent with previously published data on strain- and breed-differences pointed out in rats and men. As far as a possible sex-effect is concerned, no clear-cut evidence is likely to be drawn. Finally, P4503A expression was more relevant in small ruminants. 相似文献
48.
49.
M Jacques M E Olson A M Crichlow A D Osborne J W Costerton 《Canadian journal of veterinary research》1986,50(2):272-274
Microorganisms associated with the vagina, cervix and uterus of rabbits were isolated and identified. The predominant microorganisms isolated from the vaginas and cervices were coagulase-negative staphylococci, micrococci, and nonfermentative bacilli. Coagulase-negative staphylococci were isolated frequently, but in small numbers, from the uteri. The pH of the rabbit vagina was found to be near neutrality. Our data indicate that the genital flora of female rabbits is relatively simple, regarding the number and type of microorganisms. 相似文献
50.
Moreau M Dupuis J Bonneau NH Lécuyer M 《The Canadian veterinary journal. La revue veterinaire canadienne》2004,45(2):133-139
A powder of quality elk velvet antler (QEVA) was evaluated on client-owned dogs with osteoarthrosis (OA) in a clinical, double-blind, and placebo-controlled study. Thirteen dogs received a placebo for 30 days and then QEVA for 60 days. Twenty-five other dogs received QEVA for 60 days. Gait analysis measured with a force plate, clinical signs assessed by an orthopedic surgeon, performances in daily life activities and vitality assessed by the owners, and complete blood analyses were obtained at days 0, after 30 days of placebo and/or 60 days of QEVA. On placebo, the 13 dogs did not show significant improvement (P < 0.05); however, their gait, their performances in daily life activities, and their vitality were significantly improved on QEVA, based on changes in values exceeding those observed when placebo was administered. The 25 dogs on QEVA for 60 days showed similar improvements. No clinical changes were revealed on blood analyses. Administration of QEVA was effective in alleviating the condition in arthritic dogs. 相似文献