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   291篇
  免费   11篇
林业   6篇
农学   6篇
基础科学   4篇
  35篇
综合类   17篇
农作物   48篇
水产渔业   21篇
畜牧兽医   159篇
园艺   4篇
植物保护   2篇
  2021年   10篇
  2020年   4篇
  2019年   2篇
  2018年   3篇
  2017年   7篇
  2016年   12篇
  2015年   11篇
  2014年   17篇
  2013年   14篇
  2012年   18篇
  2011年   20篇
  2010年   13篇
  2009年   17篇
  2008年   25篇
  2007年   27篇
  2006年   12篇
  2005年   19篇
  2004年   12篇
  2003年   8篇
  2002年   9篇
  2001年   14篇
  2000年   4篇
  1999年   2篇
  1998年   4篇
  1997年   2篇
  1996年   1篇
  1993年   1篇
  1992年   1篇
  1991年   3篇
  1988年   1篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1967年   1篇
排序方式: 共有302条查询结果,搜索用时 15 毫秒
101.
Three 7-week-old, English cocker spaniel littermates were diagnosed as having juvenile cellulitis with concurrent neurologic signs based on history, histopathology, and therapeutic response. The puppies were treated with cyclosporin A and prednisolone. Skin lesions and hindlimb paresis improved following treatment.  相似文献   
102.
The effects of scoparone on dopamine release in PC12 cells were investigated. Scoparone at 50–200 µM increased dopamine release into the culture medium. However, the released levels of dopamine by scoparone were not altered in the absence of extracellular Ca2+ and by adenylyl cyclase inhibitor MDL-12,330A. Scoparone increased phosphorylation of PKA, CaMK II and synapsin I. Scoparone also enhanced K+-induced levels of dopamine release by CaMK II phosphorylation. These results suggest that scoparone increases dopamine release by synapsin I phosphorylation via activation of PKA and CaMK II, which are mediated by cyclic AMP levels and Ca2+ influx.  相似文献   
103.
104.
Anti-inflammatory and antiproliferative activities of anthocyanidins and anthocyanin-rich black soybean seed coats were studied in HT-29 human colon adenocarcinoma cells and carcinogen-treated F344 rats, respectively. Cyanidin and delphinidin significantly inhibited cell growth at concentrations of >or=1 microM. Anthocyanidins suppressed cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNAs in TPA-stimulated HT-29 cells. Both yellow and black soybean seed coat supplementation (10%, w/w) did not significantly reduce the number of aberrant crypt foci (ACF), although a modest decrease in the number of ACF was observed in animals fed soybean seed coats. The colonic COX-2 mRNA level was suppressed in rats fed both soybean seed coat diet. The plasma prostaglandin E 2 (PGE 2) level was reduced only in rats fed black soybean seed coats. No difference was observed in either colonic iNOS mRNA or plasma nitric oxide level. These results indicate that anthocyanidins are possible anti-inflammatory agents; however, further studies are required to determine required intake levels in vivo to exert antitumor effect.  相似文献   
105.
Inhibition of acyl CoA:diacylglycerol acyltransferase (DGAT), which is a key enzyme in triglyceride synthesis in eukaryotic organisms, has been proposed as one of the drug targets for treating obesity, type II diabetes mellitus, and metabolic syndrome. Bioassay-guided fractionation of EtOH extract of the flower buds of Tussilago farfara , using an in vitro DGAT enzyme assay, resulted in the isolation of four known sesquiterpenoids, tussilagonone (1), tussilagone (2), 7beta-(3-ethyl-cis-crotonoyloxy)-1alpha-(2-methylbutyryloxy)-3,14-dehydro-Z-notonipetranone (3), and 8-angeloylxy-3,4-epoxy-bisabola-7(14),10-dien-2-one (4). DGAT1 inhibitory activity was studied by in vitro DGAT assay using rat liver microsomes and HepG2 cell microsomes. They showed DGAT1 inhibition with IC(50) values of 99.2 (1), 18.8 (2), 47.0 (3), and 211.1 (4) microM (for rat liver microsomes) and >1 mM (1), 49.1 (2), 160.7 (3), and 294.4 (4) microM (for HepG2 cell microsomes), respectively. Compound 2 showed the most potent inhibition against microsomal DGAT1 derived from rat liver and human hepatocellular carcinoma HepG2 cells and also significantly inhibited triglyceride synthesis by suppressing incorporation of [(14)C]acetate or [(14)C]glycerol into triglycerides in HepG2 cells. These findings suggest that tussilagone is a potential lead compound in the treatment of obesity and type 2 diabetes.  相似文献   
106.
A 14‐wk feeding trial was carried out to evaluate the optimum dietary riboflavin (vitamin B2) level in juvenile sea cucumber, Apostichopus japonicus. A total of 360 sea cucumbers averaging 1.49 ± 0.07 g (mean ± SD) were randomly distributed into 18 rectangular plastic tanks, and each tank was then randomly assigned to one of three replicates of six diets containing 0.29 (B20), 4.22 (B24), 8.93 (B29), 17.9 (B218), 56.7 (B257), and 577 (B2577) mg riboflavin/kg diet. At the end of 14 wk of feeding trial, average weight gain (WG) of sea cucumbers fed B29, B218, B257, and B2577 diets were significantly (P < 0.05) higher than that of animals fed B20 diet. WG of sea cucumbers fed B218, B257, and B2577 diets were significantly higher than those of animals fed B20 and B24 diets. Specific growth rate of sea cucumbers fed B29, B218, B257, and B2577 diets were significantly higher than those of animals fed B20 and B24 diets. Feed efficiency of sea cucumbers fed B29, B257, and B2577 diets were significantly higher than those of animals fed B20 and B24 diets. Although significant differences were recorded in proximate composition of sea cucumbers fed the experimental diets, no clear trends were observed. The ANOVA test suggested that the optimum dietary riboflavin level in sea cucumber could be 17.9 mg/kg diet but broken‐line analysis of WG indicated a level of 9.73 mg riboflavin/kg diet. Therefore, these results may indicate that the optimum dietary riboflavin level in sea cucumber could be higher than 9.73 mg/kg diet but lower than 17.9 mg/kg diet.  相似文献   
107.
Sulfur (S) nutrition has a strong influence on onion pungency, and the production of sweet onions in the high-sulfur soil of Texas is a challenge to growers. This study was performed to determine the effects of S applications to fields already having sufficient levels of soil S on pungency and related compounds in four shortday onion cultivars. The onion cultivars ‘Cougar’, ‘Legend’, ‘Texas Early White’, and ‘Texas Grano 1015Y’ were grown in three commercial fields at Edinburg, Mercedes, and Weslaco of the Rio Grande Valley of South Texas with applications of sulfur at 0, 13, and 26 kg S/ha. Pyruvic acid, bulb weight, extractable S in soil and total S in bulb, soluble solids content (SSC), flavor precursor compounds [also called S-alk(en)yl-l-cysteine-sulfoxides (ACSOs)], and total sugars were measured. The pyruvic acid level of onions was not increased by the S applications and showed no significant correlation with soil S levels in any of the cultivars at locations having 30 or 235 ppm S. The SSC, total S in bulbs, total sugars, and total ACSO content also showed no correlation with the S applications and soil S levels. Onion pungency and content of flavor precursor compounds were significantly influenced by cultivar and cultivar × location interaction. We conclude that onion pungency is not increased by application of extra S fertilizer to commercial fields already containing sufficient levels of soil sulfur.  相似文献   
108.
1. Shedding of group-specific antigen of avian leukosis virus (ALV) into egg albumen was determined in three Australorp lines: AS line that had been selected primarily for short oviposition interval, ASS line that had been derived from the AS line and developed as a commercial dam line for egg laying, and AC line that had been kept as a randombred control. 2. The proportion of shedders was 13.1 to 16.7% in the AS line in 1984-88, 16.3% in the ASS line in 1984 (before culling of the shedders), and 6.1% and 6.6% in the AC line in 1984 and 1988, respectively. 3. In the AS line, shedders were 1.8% lower in rate of lay to 300 d of age, 1.3 g lower in average egg weight at 34 weeks of age, 5.6% lower in hatchability of fertile eggs and 0.24 h shorter in oviposition interval than non-shedders. In the ASS line (1984 only), the differences between shedders and non-shedders were in the same direction, but in magnitude greater for rate of lay and smaller for oviposition interval. 4. The shedders were favoured by the artificial selection because of their shorter oviposition interval and this appeared to be responsible for the higher levels of ALV shedding in the selection lines.  相似文献   
109.
1. Association of the B blood group, the major histocompatibility complex (MHC) in chickens, with avian leukosis virus (ALV) infection shown by shedding of group-specific (gs) antigen was studied in an Australorp line selected for short oviposition interval to improve egg production. Three haplotypes (B8a, B9a and B21) were segregating in this line at frequencies of 66.7, 15.6 and 17.8%, respectively, averaged over three generations. 2. The relative risk (odds ratio) of a hen becoming a gs-antigen shedder was calculated for progenies of the dams shedding gs-antigen and those of non-shedding dams separately and pooled over three generations. In the progenies of shedding dams, the relative risk was not significantly different from 1.0 for the three haplotypes. In contrast, in the progenies of non-shedding dams, the relative risk was 0.67, 0.48 and 2.53 for B8a, B9a and B21, respectively, with the last two ratios being significantly different from 1.0. 3. The average effect of haplotype substitution on probability of shedding was estimated from a linear logistic model. The estimates (relative to zero for B8a) for B9a and B21, respectively, were -0.26 and 0.03 among the progenies of shedding dams, and -0.16 and 0.87 among the progenies of non-shedding dams. The last estimate only was highly significant. 4. These results suggest that the three haplotypes were similar in susceptibility to congenital infection through hatching eggs, but differed in susceptibility to post-hatching infection from other infected birds.  相似文献   
110.
1. The effect of preincubation storage of chicken eggs on hatchability was studied in an Australorp subline (ASS) that had shown a steady decrease of hatchability compared with the original selection line (AS) since its derivation 10 generations ago. The AS line was also included in the study.

2. Eggs were collected over 21 d and the collected eggs were stored at 10° to 12°C and relative humidity of 70 to 80% until they were set together on d 21. Fertility and hatchability of fertile eggs were calculated for each d of collection to study their relationships with age of eggs (length of storage).

3. The hatchability of fertile eggs was considerably different between the two lines in the average over 21 d and, more importantly, in the pattern of decline with length of storage.

4. In the first 3 to 4 d of storage, hatchability was very similar between the lines. However, it decreased linearly at a rate of 1.9% per day of storage over the 21‐d period in the ASS line (average 65.9%), whereas in the AS line (average 78.6%), it stayed at around 84% up to 12 d of storage, when it started to decline at a similar rate as in the ASS line.

5. Fertility was 2.6% higher in the AS line than in the ASS line, but in each line showed no significant trend with age of eggs.  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