全文获取类型
收费全文 | 925篇 |
免费 | 35篇 |
专业分类
林业 | 473篇 |
农学 | 8篇 |
106篇 | |
综合类 | 56篇 |
农作物 | 16篇 |
水产渔业 | 30篇 |
畜牧兽医 | 196篇 |
园艺 | 24篇 |
植物保护 | 51篇 |
出版年
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 11篇 |
2017年 | 23篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 23篇 |
2013年 | 23篇 |
2012年 | 39篇 |
2011年 | 46篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 34篇 |
2007年 | 36篇 |
2006年 | 42篇 |
2005年 | 26篇 |
2004年 | 30篇 |
2003年 | 23篇 |
2002年 | 19篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1995年 | 4篇 |
1987年 | 5篇 |
1948年 | 30篇 |
1944年 | 5篇 |
1943年 | 13篇 |
1942年 | 49篇 |
1941年 | 32篇 |
1940年 | 36篇 |
1939年 | 45篇 |
1938年 | 27篇 |
1937年 | 21篇 |
1936年 | 14篇 |
1935年 | 35篇 |
1934年 | 7篇 |
1931年 | 14篇 |
1930年 | 7篇 |
1927年 | 5篇 |
1926年 | 6篇 |
1925年 | 4篇 |
1919年 | 3篇 |
1913年 | 3篇 |
1912年 | 4篇 |
1911年 | 3篇 |
1910年 | 3篇 |
1902年 | 3篇 |
1901年 | 5篇 |
排序方式: 共有960条查询结果,搜索用时 15 毫秒
61.
Rodríguez C Frías J Vidal-Valverde C Hernández A 《Journal of agricultural and food chemistry》2007,55(25):10275-10280
The effect of the germination of peas, beans, and lentils under differing conditions of illumination for different times on parameters linked to the Maillard reaction (chemically available free and intrachain lysine, lysine availability, and furosine) was evaluated. The chemically available free lysine content in the raw seeds of the three legumes was quite small compared to the chemically available intrachain lysine content, and furosine was detectable only in the beans and the lentils. The effect of germination was to increase lysine availability compared with levels in the raw seeds in all of the germinated samples, the smallest increase taking place in the lentils. In addition, furosine became detectable in all of the germinated samples. Quantities varied depending on the germination conditions but in all cases were higher than the quantities observed in the raw seeds. Linear correlations were observed to exist between some of the parameters considered in the three legumes tested. 相似文献
62.
Billard Antoine Bauer Rodolphe Mothe Frédéric Colin Francis Christine Deleuze Longuetaud Fleur 《European Journal of Forest Research》2021,140(6):1401-1416
European Journal of Forest Research - Studies on wood basic density (BD) vertical variations become essential to predict more accurately the within-stem distributions of biomass and wood quality in... 相似文献
63.
Anna Ohlson Jonas Malmsten Jenny Fr?ssling G?ran B?lske Anna Aspán Anne-Marie Dalin Ann Lindberg 《Acta veterinaria Scandinavica》2014,56(1):39
Background
Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Prevalence data in ruminant species are important to support risk assessments regarding public and animal health. The aim was to investigate the presence of or exposure to C. burnetii in cattle, sheep, goats and moose, and to compare two enzyme-linked immunosorbent assays (ELISAs). National surveys of antibodies against C. burnetii were performed for dairy cattle (n=1537), dairy goats (n=58) and sheep (n=518). Bovine samples consisted of bulk milk, caprine of pooled milk, and ovine of pooled serum. Antibodies were investigated in moose samples (n=99) from three regions. A one-year regional cattle bulk milk survey was performed on the Isle of Gotland (n=119, four occasions). Cattle, sheep and goat samples were analysed with indirect ELISA and moose samples with complement fixation test. For the sheep, goat, and parts of the cattle survey, samples were run in parallel by ELISAs based on antigens from infected ruminants and ticks. Bulk milk samples from the regional cattle survey and vaginal swabs from a subset of the sheep herds (n=80) were analysed for the agent by polymerase chain reaction. Spatial clustering was investigated in the national cattle survey.Results
The prevalence of antibodies in dairy herds was 8.2% with large regional differences. High risk clusters were identified in the southern regions. The prevalence among dairy herds on the Isle of Gotland varied from 55.9% to 64.6% and 46.4% to 58.9.0% for antibodies and agent, respectively, overall agreement between agent and antibodies was 85.2%. The prevalence of antibodies in sheep was 0.6%, the agent was not detected the vaginal swabs. Antibodies were not detected in goats or moose, although parts of the moose samples were collected in an area with high prevalence in cattle. The overall agreement between the two ELISAs was 90.4%.Conclusions
The prevalence of antibodies against C. burnetii in dairy cattle in Sweden shows large regional differences. The results suggest that C. burnetii is a rare pathogen among Swedish moose, dairy goat and sheep. ELISAs based on ruminant and tick antigen performed in a similar manner under Swedish conditions. 相似文献64.
Guillaume Sallé Carole Moreno Simon Boitard Julien Ruesche Aurélie Tircazes-Secula Frédéric Bouvier Mathias Aletru Jean-Louis Weisbecker Fran?oise Prévot Jean-Paul Bergeaud Cathy Trumel Christelle Grisez Emmanuel Liénard Philippe Jacquiet 《Veterinary research》2014,45(1):68
This study reports a functional characterization of a limited segment (QTL) of sheep chromosome 12 associated with resistance to the abomasal nematode Haemonchus contortus. The first objective was to validate the identified QTL through the comparison of genetically susceptible (N) and resistant (R) sheep produced from Martinik × Romane back-cross sheep. The R and N genotype groups were then experimentally infected with 10 000 H. contortus larvae and measured for FEC (every three days from 18 to 30 days post-challenge), haematocrit, worm burden and fertility. Significant differences in FEC and haematocrit drop were found between R and N sheep. In addition, the female worms recovered from R sheep were less fecund. The second step of the characterization was to investigate functional mechanisms associated with the QTL, thanks to a gene expression analysis performed on the abomasal mucosa and the abomasal lymph node. The gene expression level of a candidate gene lying within the QTL region (PAPP-A2) was measured. In addition, putative interactions between the chromosome segment under study and the top ten differentially expressed genes between resistant MBB and susceptible RMN sheep highlighted in a previous microarray experiment were investigated. We found an induction of Th-2 related cytokine genes expression in the abomasal mucosa of R sheep. Down-regulation of the PAPP-A2 gene expression was observed between naïve and challenged sheep although no differential expression was recorded between challenged R and N sheep. The genotyping of this limited region should contribute to the ability to predict the intrinsic resistance level of sheep. 相似文献
65.
66.
67.
Chanlun A Emanuelson U Frössling J Aiumlamai S Björkman C 《Veterinary parasitology》2007,146(3-4):242-248
A long-term study was carried out in 11 dairy herds in the Khon Kaen province of northeast Thailand between August 2001 and November 2004. The objective was to investigate seroprevalence dynamics of Neospora caninum infection in the herds and to demonstrate patterns of seroconversion in individual cattle. Each herd was visited once a year, in total four times, and sera from cattle > 3 months of age and farm dogs as well as a sample from the bulk milk were collected. All samples were analysed for presence of specific antibodies by an N. caninum iscom ELISA. The overall percentage of antibody-positive cattle was constant and varied only between 10 and 13% over the 4 years, but the variation in within-herd seroprevalence between herds was substantial. Two herds had > or = 20% seropositive animals at all samplings and consistently high bulk milk OD, whereas two herds had no seropositive animal at the last two samplings and low bulk milk OD. Five herds had a decreasing trend of within-herd seroprevalence, whereas the remaining six herds had a higher portion of test-positive individuals at the end of the study. A total of 424 individuals were sampled more than once; 344 (81%) and 32 (8%) were consistently antibody-negative and antibody-positive, respectively. The proportions of animals that changed from being seronegative to seropositive and from being seropositive to seronegative between the years were 3.9-4.6% and 19-39%, respectively. Apparent vertical and horizontal transmission rates were 58% (95% CI; 44-71%) and 5% (95% CI; 3-7%), respectively. In conclusion, the overall percentage of N. caninum antibody-positive cattle was constant over the years, but the within-herd seroprevalence varied substantially between the herds. Seroconversions were likely to occur in individual cattle although most animals had consistent serological status throughout the study. 相似文献
68.
69.
Fr. 《Journal of pest science》1948,21(4):64
Ohne Zusammenfassung 相似文献
70.
Cortés C Esteve MJ Frígola A Torregrosa F 《Journal of agricultural and food chemistry》2004,52(8):2203-2212
A method was established for the identification and quantification of carotenoids including geometrical isomers in fruit and vegetable juices by liquid chromatography with an ultraviolet-diode array detector, using a C(18) Vydac 201TP54 column. The mobile phase used was the ternary methanol mixture (0.1 M ammonium acetate), tert-butyl methyl ether and water, in a concentration gradient, and a temperature gradient was applied. Retinol palmitate was added as an internal standard. An extraction process (ethanol/hexane, 4:3, v/v) was performed, followed by saponification with diethyl ether/methanolic KOH (0.1%, w/v, BHT) (1:1, v/v) for 0.5 h at room temperature. Seventeen different (cis and trans) carotenoids were identified by UV-vis spectra and retention times in HPLC in the juices analyzed. The analytic parameters show that the method proposed is sensitive, reliable, accurate, and reproducible. 相似文献