首页 | 官方网站   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   284篇
  免费   28篇
  国内免费   10篇
农业科学   322篇
  2023年   5篇
  2022年   7篇
  2021年   16篇
  2020年   15篇
  2019年   4篇
  2018年   4篇
  2017年   9篇
  2016年   11篇
  2015年   16篇
  2014年   16篇
  2013年   20篇
  2012年   18篇
  2011年   21篇
  2010年   14篇
  2009年   26篇
  2008年   9篇
  2007年   13篇
  2006年   6篇
  2005年   8篇
  2004年   15篇
  2003年   13篇
  2002年   6篇
  2001年   9篇
  2000年   6篇
  1999年   3篇
  1998年   5篇
  1997年   6篇
  1996年   4篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1985年   2篇
  1979年   1篇
排序方式: 共有322条查询结果,搜索用时 15 毫秒
1.

Background

People with critical illness (CI) commonly develop various forms of immune dysfunction, however, there is limited information concerning immune dysfunction in dogs with CI.

Hypothesis

The immune response in CI dogs differs from that of healthy dogs.

Animals

Immunologic variables were compared between 14 dogs with CI, defined as APPLEfast score of >20 points, admitted to the University of Missouri Veterinary Health Center Small Animal Clinic Intensive Care Unit and healthy controls (n = 15).

Methods

Cohort study evaluating constitutive and lipopolysaccharide (LPS)‐stimulated TNF‐α, IL‐6, and IL‐10 production, phagocytosis of opsonized E. coli and respiratory burst capacity after opsonized E. coli or phorbol 12‐myristate 13‐acetate (PMA) stimulation, peripheral blood lymphocyte phenotype, and monocyte expressions of HLA‐DR and TLR‐4.

Results

Lipopolysaccharide‐stimulated leukocyte TNF‐α (median, Q1, Q3; CI, 49, 49, 120; control, 655, 446, 1174 pg/mL; P = < 0.001), IL‐6 (median, Q1, Q3; CI, 49, 49, 64; control, 100, 49, 166 pg/mL; P = 0.029), and IL‐10 (CI, 49, 49, 56; control, 96, 49, 203 pg/mL; P = 0.014) production and both E. coli (median, Q1, Q3; CI, 60.5, 43, 88.5; control, 86.6, 81, 89.2%; P = 0.047) and PMA (CI, 40, 11.7, 70; control, 93, 83, 97.6%; P = < 0.001)‐stimulated respiratory burst capacity significantly decreased in CI dogs. Percentage of monocytes expressing TLR‐4 greater in the CI dogs (median, Q1, Q3; CI, 46.9, 24.3, 64.2; control, 16.4, 9.4, 26.2%; P = 0.005).

Conclusion

These findings suggest dogs with CI develop immune system alterations that result in reduced respiratory burst function and cytokine production despite upregulation of TLR‐4.  相似文献   
2.
The use of the selective inhibition (SI) method for measuring fungal:bacterial ratios may be limited due to biocide selectivity and the overlap of antibiotic activity. This study evaluated novel pairs of antibiotics for their specificity in soils of different origins and their potential reduction in inhibition of non-target organisms. Four soils selected for this study were from a semi-arid shrub-steppe, a loblolly pine forest and two grassland sites (restored and farmed prairie plots). Three bactericides were tested: oxytetracycline hydrochloride, streptomycin sulphate, and bronopol. Three fungicides were tested: captan, ketoconazole, and nystatin. The inhibitor additivity ratio and fungal:bacterial ratios were calculated from control and treated soils where inhibition was measured as CO2 respiration reduction with biocides. We were able to minimize non-target inhibition by the antibiotics to <5% and thus calculate reliable fungal:bacterial ratios using captan to inhibit fungi in all four soils, and bronopol to inhibit bacteria in three of the four soils. The most successful bactericide in the restored prairie was oxytetracycline-HCl. Our results demonstrate that application of novel antibiotics is not uniformly successful in soils of different origin and that the SI technique requires more than just optimization of antibiotic concentration; it also requires optimization of antibiotic selection.  相似文献   
3.
选择平均体重为26.6kg的无角多赛特断奶大羔羊22只.平均体重为49.3kg的无角多赛特育成羊48只,分别分为对照组和试验组,试验组羊只精料补充料中添加300mg/kg的茶黄酮,研究茶黄酮对羊只生长和呼吸道疾病的影响。结果表明,添加茶黄酮可提高羔羊和育成羊的增重效果.和对照组比较羔羊提高增量9.8%(P〉0.05),育成羊提高增重6.1%(P〉0.05);在饲料中添加茶黄酮可使羔羊呼吸道疾病发病率降低64%,使育成羊呼吸道疾病发病率降低50%,可有效预防羊的呼吸道疾病。  相似文献   
4.
猪繁殖与呼吸综合征病毒的研究进展   总被引:2,自引:0,他引:2  
从遗传变异、检测以及宿主免疫3个方面,对近年来在猪繁殖与呼吸综合征病毒(PRRSV)方面的研究进行简要综述。  相似文献   
5.
6.
7.
Epithelial sodium channel (ENaC) is an ion channel widely distributed in various tissues and organs of human. It is composed of 3 homologous subunits and allows the flow of sodium ion across epithelial cells, maintain?ing water-salt balance in the cells. Recent studies show that abnormal expression or dysfunction of ENaC in the respiratory system affects water-salt balance, fluid transportation and cell mobility, and causes abnormal changes of the airway surface liquid level and impaired clearance. ENaC is closely related to the development of respiratory diseases, such as cystic fibrosis, asthma and chronic obstructive pulmonary disease. This article reviews the progress in ENaC structure, function and roles in related respiratory diseases in order to provide a reference for the treatment of the diseases.  相似文献   
8.
麻竹山地笋用林笋期叶片光合及呼吸性状研究   总被引:9,自引:1,他引:9  
Through analyzing the various position leaves character of 3 ages bamboo, including net photosyntheticrate, light respiratory rate, dark respiratory rate, CO2 compensation point and light compensation point, in five-years - old forest during different growing shoot stages in stated - own forestry farm of Nanjin, results showed thatleaves had vigorous physiological function during prosperity stage of growing shoot. Net photosynthetic rate was high-er, light respiratory rate, dark respiratory rate, CO2 compensation point and light compensation point were lower,the photosynthetic coefficients was larger.2- year bamboo and 3 - year bamboo had stronger photosynthetic ability. Different photosynthetic and respiratory indexes of various position leaves were not consistent, but in generally, mid-dle leaf had stronger assimilation ability.  相似文献   
9.
用大体解剖学方法研究了羊驼呼吸系统的形态结构,用组织学方法研究了羊驼肺的组织结构,并与文献报道的骆驼的呼吸系统,牛、羊、马、猪等的呼吸系统进行了比较。结果显示,羊驼呼吸系统的组成与其它家畜相同,都是由鼻、咽、喉、气管、支气管和肺组成,但各器官有其特点。羊驼呼吸系统形态结构类似于骆驼和马,肺的组织结构类似于其它家畜,但也有其独特之处。  相似文献   
10.
BACKGROUND: Horses with recurrent airway obstruction (heaves) are described as exhibiting "increased abdominal effort," but it is unknown whether this translates to an effective contribution to ventilation. HYPOTHESIS: We hypothesized that heaves is characterized by asynchrony between rib cage and abdominal motions, and that the abdominal component is the major contributor to ventilation. ANIMALS: The rib cage versus abdominal motion in naturally occurring heaves (n = 15) was compared to controls at rest (n = 7) and during hyperpnea because of lobeline treatment, and the effects of histamine-induced bronchoconstriction in controls (n = 10). METHODS: Flow patterns, phase angle (theta) between the rib and abdominal compartments, abdominal (Vabd) contribution to tidal volume (VT), and lung mechanics were measured. RESULTS: Findings unique to the heaves group included the loss of biphasic expiratory flow, severely increased theta with the abdomen consistently lagging behind the rib cage, and a reduced contribution of the abdomen to ventilation. A subgroup of heaves (n = 5) with abdominal paradox showed a significant (P < .05) reduction in tidal volume, and increased respiratory rate. Bronchodilation reduced theta in heaves (P = .06), but theta remained significantly higher after bronchodilation than found in controls. CONCLUSIONS AND CLINICAL IMPORTANCE: We conclude that breathing pattern in horses with heaves is characterized by severe rib cage/abdominal asynchrony, with the rib cage motion in synchrony with flow, therefore dominating ventilation. In a subset of heaves, the abdominal compartment (diaphragm, abdominal muscles) was completely out of synchrony with flow ("abdominal paradox") despite the clinical appearance of "increased abdominal effort."  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-23

京公网安备 11010802026262号