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   228篇
  免费   9篇
林业   4篇
农学   1篇
  39篇
综合类   26篇
农作物   7篇
水产渔业   16篇
畜牧兽医   133篇
植物保护   11篇
  2021年   2篇
  2020年   3篇
  2019年   3篇
  2018年   4篇
  2017年   2篇
  2016年   4篇
  2015年   3篇
  2014年   9篇
  2013年   11篇
  2012年   7篇
  2011年   17篇
  2010年   4篇
  2009年   7篇
  2008年   15篇
  2007年   15篇
  2006年   10篇
  2005年   5篇
  2004年   6篇
  2003年   4篇
  2002年   9篇
  2001年   5篇
  2000年   7篇
  1999年   7篇
  1998年   3篇
  1995年   3篇
  1992年   5篇
  1991年   3篇
  1989年   5篇
  1988年   4篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   4篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1974年   5篇
  1973年   3篇
  1972年   3篇
  1971年   2篇
  1970年   6篇
  1969年   1篇
  1966年   2篇
  1961年   1篇
  1949年   1篇
  1948年   1篇
排序方式: 共有237条查询结果,搜索用时 31 毫秒
31.
Under conditions designed to imitate heavy natural contamination of equipment, animal cages, etc. virus was exposed to ethylene oxide treatment.The effect on strains of the enterovirus types Coxsackie B3 and ECHO 11, of vaccinia virus and of Newcastle disease virus was studied. The viruses were all inactivated by a treatment which was considered sufficient from a bacteriological point of view.Keyword: ethylene oxide, virus inactivation  相似文献   
32.
Polymorphonuclear neutrophils (PMN) from 4 ovariectomized healthy cows were incubated with 0 (control), 10(-8), 10(-7), and 10(-6) M arachidonic acid metabolites of the cyclo- and lipoxygenase pathways for 30 minutes, and with steroids for 2 hours. Immediately after incubation, PMN were subjected to the following function assays: chemotaxis against zymosan-activated serum, chemotaxis against arachidonic acid metabolite or steroid at the doses given (only control PMN were tested), random migration, ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus (125I-IdUR-S aureus), iodination of proteins, cytochrome C reduction, antibody-independent and -dependent cell-mediated cytotoxicity (AICC and ADCC). Prostaglandin F2 alpha was chemoattractant and stimulated ingestion of 125I-IdUR-S aureus. Prostaglandin E2 stimulated cytochrome C reduction, whereas prostacyclin inhibited iodination of proteins. Thromboxane B2 stimulated ADCC. Leukotriene B4 was chemoattractant for bovine PMN and stimulated random migration and AICC. 5-Hydroxyeicosatetraenoic acid was also chemoattractant, but inhibited ingestion of 125I-IdUR-S aureus. 15-Hydroxyeicosatetraenoic acid was chemoattractant and decreased ADCC. Lipoxin A4 stimulated random migration, whereas lipoxin B4 inhibited chemotaxis against zymosan-activated serum, but was chemoattractant and stimulated cytochrome C reduction. 12-Hydroxyhepadecatrienoic acid and 12-hydroxyeicosatetraenoic acid did not influence any of the PMN functions tested. Of the steroids tested, cortisol increased ADCC, and progesterone stimulated cytochrome C reduction, but decreased ADCC. 17 beta-Estradiol and estrone were chemoattractant and stimulated cytochrome C reduction. In addition, estrone also stimulated random migration.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
33.
Cysticercosis is due to the establishment of the larval stage of the zoonotic cestode parasite Taenia solium. The infection causes substantial human morbidity and mortality, particularly in several Latin American countries and parts of Africa and Asia, as well as economic losses in pig husban dry due to condemnation of infected pork meat. The life cycle of T. solium includes human beings as definitive hosts and pigs as intermediate hosts. Cysticercosis is acquired by the ingestion of eggs released by human tapeworm carriers, who become infected after ingesting pork meat contaminated with cysticerci. Taenia solium transmission has been associated with poverty, lack of sanitary services and practices of rearing backyard pigs with free access to the areas that villagers use as toilets, as well as cultural behaviour. Nonetheless, due to the recent increase of migration and tourism, industrial countries are also reporting cases of human cysticercosis. There are many epidemiological studies that have been conducted mainly in Latin American countries that have evaluated intervention measures for control of cysticercosis including the development and testing of vaccines. Furthermore, the involvement of international agencies and institutions, such as the World Health Organization, the Food and Agriculture Organization and the International Livestock Research Institute, as well as the commitment of policymakers, scientists and field workers, are key means for the sustainable control and, hopefully, eradication of T. solium infections.  相似文献   
34.
The posttranslational modification sumoylation can have multiple effects on its substrate proteins. We studied a patient with isolated cleft lip and palate and a balanced chromosomal translocation that disrupts the SUMO1 (small ubiquitin-related modifier) gene, resulting in haploinsufficiency. In mouse, we found that Sumo1 is expressed in the developing lip and palate and that a Sumo1 hypomorphic allele manifests an incompletely penetrant orofacial clefting phenotype. Products of several genes implicated in clefting are sumoylated, and the Sumo1 hypomorphic allele interacts genetically with a loss-of-function allele for one of these loci. Thus, sumoylation defines a network of genes important for palatogenesis.  相似文献   
35.
36.
1. The mortality of broilers during pre-slaughter handling, including harvesting and transport, is an issue of increasing public concern which has led to the adoption of Council Directive EC/43/2007 implementing abattoir surveillance regarding the number of dead-on-arrival (DOA) broilers.

2. Pathological lesions and causes of death of DOA broilers at a Danish abattoir were investigated in a cross-sectional study comprising 300 DOA broilers (25 broilers from each of 12 randomly selected flocks). Major pathological manifestations of DOA broilers included severe pulmonary congestion (51.5%), lung congestion in combination with trauma (12.5%), trauma (10.2%), nephropathy accompanied by dehydration and/or discolouration (8.8%), morbus cordis (2.0%), septicaemia (1.7%) and suspected septicaemia (1.0%). Lung congestion accompanied by circulatory disturbances in other tissues was suggested to be due to suffocation.

3. Analyses of pathological diagnoses revealed that DOA broilers can be divided into two main categories, lung congestion and trauma, based on the chronicity of the lesions, both of which are primarily related to management and handling procedures. Most DOA broilers examined (74.2%) were estimated to have died as a consequence of events during pre-slaughter handling underlining the importance of increased focus on handling-related factors to reduce DOA rate.  相似文献   

37.
1. Two experiments were conducted to study the effect of intermittent feeding on performance and the efficacy of an exogenous phytase, and to assess whether intermittent feeding changed the activity pattern of broiler chickens.

2. Broiler chickens were given, either ad libitum or intermittently, a phosphorus deficient pelleted diet containing either coarsely or finely ground oat hulls and either no enzyme or a phytase added from 10 d of age, in a 2 × 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 1-h feeding bouts/d and one 2-h feeding bout/d from d 14.

3. Performance, characteristics of the anterior digestive tract and phosphorus retention were assessed in experiment 1, while in experiment 2, birds were observed during 4-h periods to quantify different behaviours.

4. Intermittent feeding and phytase improved performance, but intermittent feeding did not improve the efficacy of the enzyme added. Ad libitum fed broiler chickens ate and drank on average twice per hour, and spent close to three-quarters of their time resting. Apart from an increased standing and feed searching activity for intermittently fed birds compared to ad libitum fed birds during the last hour before feed was presented, no differences in activity was detected.

5. It was concluded that broiler chickens quickly adapt to intermittent feeding without reduction in final body weight and with improvements in feed efficiency, but without improving the efficacy of dietary phytase. Only small changes occur in the behaviour of intermittently fed birds compared to ad libitum fed birds.  相似文献   

38.
Breeding animals can be accurately evaluated using appropriate genomic prediction models, based on marker data and phenotype information. In this study, direct genomic values (DGV) were estimated for 16 traits of Nordic Total Merit (NTM) Index in Nordic Red cattle population using three models and two different response variables. The three models were as follows: a linear mixed model (GBLUP), a Bayesian variable selection model similar to BayesA (BayesA*) and a Bayesian least absolute shrinkage and selection operator model (Bayesian Lasso). The response variables were deregressed proofs (DRP) and conventional estimated breeding values (EBV). The reliability of genomic predictions was measured on bulls in the validation data set as the squared correlation between DGV and DRP divided by the reliability of DRP. Using DRP as response variable, the reliabilities of DGV among the 16 traits ranged from 0.151 to 0.569 (average 0.317) for GBLUP, from 0.152 to 0.576 (average 0.318) for BayesA* and from 0.150 to 0.570 (average 0.320) for Bayesian Lasso. Using EBV as response variable, the reliabilities ranged from 0.159 to 0.580 (average 0.322) for GBLUP, from 0.157 to 0.578 (average 0.319) for BayesA* and from 0.159 to 0.582 (average 0.325) for Bayesian Lasso. In summary, Bayesian Lasso performed slightly better than the other two models, and EBV performed slightly better than DRP as response variable, with regard to prediction reliability of DGV. However, these differences were not statistically significant. Moreover, using EBV as response variable would result in problems with the scale of the resulting DGV and potential problem due to double counting.  相似文献   
39.
OBJECTIVE: The purpose of this work was to identify dietary patterns in the past using cluster analysis of reported diet in childhood, and to assess predictors for dietary patterns in relation to ethnicity in the population in the Sámi core areas in Norway. The Sámis are an indigenous population living in the border areas of Norway, Sweden, Finland and Russia. DESIGN: Population-based, cross-sectional study, using self-administered questionnaires. A food-frequency questionnaire covering selected food items eaten in childhood was used. The questionnaire also provided data on ethnicity. SUBJECTS AND SETTING: This study was based on data collected from 7614 subjects participating in The Population Based Study of Health and Living Conditions in Areas with a Mixed Sámi and Norwegian Population (the SAMINOR study) who grew up in the SAMINOR geographical areas, i.e. areas with mixed Sámi and Norwegian populations in Norway. RESULTS: Four dietary clusters were identified: a reindeer meat cluster; a cluster with high intakes of fish, traditional fish products and mutton, in addition to food sources from the local environment; a Westernised food cluster with high intakes of meat balls and sausages; and a cluster with a high intake of fish, but not any other foods in the questionnaire. The cluster distribution differed by ethnicity, but the effect of ethnicity on diet differed by coastal and inland residence. CONCLUSION: Our study has shown that data gathered through the limited questionnaire could be used to group the study sample into different dietary clusters, which we believe will be useful for further research on relationships between diet in childhood and health in the Sámi core areas in Norway.  相似文献   
40.
Acrylamide exposure was investigated in subgroups of the EPIC study population (510 subjects from 9 European countries, randomly selected and stratified by age, gender, and smoking status) using hemoglobin adducts of acrylamide (HbAA) and its primary metabolite glycidamide (HbGA). Blood samples were analyzed for HbAA and HbGA by HPLC/MS/MS. Statistical models for HbAA and HbGA were developed including body mass index (BMI), educational level, and physical activity. A large variability in acrylamide exposure and metabolism between individuals and country groups was observed with HbAA and HbGA values ranging between 15-623 and 8-377 pmol/g of Hb, respectively. Both adducts differed significantly by country, sex, and smoking status. HbGA values were significantly lower in high alcohol consumers than in moderate consumers. With increasing BMI, HbGA in nonsmokers and HbAA in smokers decreased significantly. In the assessment of potential health effects related to acrylamide exposure, country of origin, BMI, alcohol consumption, sex, and smoking status should be considered.  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