全文获取类型
收费全文 | 793篇 |
免费 | 62篇 |
专业分类
林业 | 85篇 |
农学 | 30篇 |
基础科学 | 7篇 |
196篇 | |
综合类 | 38篇 |
农作物 | 37篇 |
水产渔业 | 117篇 |
畜牧兽医 | 249篇 |
园艺 | 23篇 |
植物保护 | 73篇 |
出版年
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 33篇 |
2020年 | 47篇 |
2019年 | 62篇 |
2018年 | 39篇 |
2017年 | 32篇 |
2016年 | 40篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 47篇 |
2012年 | 66篇 |
2011年 | 52篇 |
2010年 | 48篇 |
2009年 | 33篇 |
2008年 | 44篇 |
2007年 | 50篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1978年 | 1篇 |
排序方式: 共有855条查询结果,搜索用时 31 毫秒
91.
Nutritional Contribution of Biofloc within the Diet of Growout and Broodstock of Litopenaeus vannamei,Determined by Stable Isotopes and Fatty Acids
下载免费PDF全文
![点击此处可从《Journal of the World Aquaculture Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Edén Magaña‐Gallegos Rodrigo González‐Zúñiga Gerard Cuzon Miguel Arevalo Eduardo Pacheco Manuel A. J. Valenzuela Gabriela Gaxiola Elisa Chan‐Vivas Korinthia López‐Aguiar Elsa Noreña‐Barroso 《Journal of the World Aquaculture Society》2018,49(5):919-932
The relative contributions of feed sources were determined through the isotopic signal (δ13C and δ15N) and fatty acid profile of feed items, shrimp muscle, and eggs of Litopenaeus vannamei reared in a biofloc system. In the growout phase, the isotope analysis showed the biofloc particle size class ≥250 μm contributed 55–100%; size ≥50 < 250 μm contributed 0–22%; and artificial feed contributed 0–45%. Principal component analysis applied to fatty acid profiles showed that biofloc ≥250 μm and artificial feed were the most important items in shrimp growout. For the egg production, isotope analysis suggested that the most important feed sources according to their relative contributions were polychaetes (0–100%), followed by artemia biomass (0–86%) and semi‐moist feed (0–66%), with lower contributions from squid, mussel, and the muscle of L. vannamei broodstock that had been cultured in biofloc. In terms of fatty acids, the most important items were artemia, polychaetes, and semi‐moist feeds. This work clarified the importance of feed sources for shrimp during culture in biofloc systems and during reproduction. Analysis of stable isotopes and fatty acids can be successfully used to trace the assimilation of nutrients during the nutrition of shrimp. 相似文献
92.
Ribeiro VL Avancini C Gonçalves K Toigo E von Poser G 《Veterinary parasitology》2008,151(2-4):351-354
Calea serrata (Asteraceae) is an endemic Southern Brazilian plant species used for religious and medicinal purposes. Previous study revealed the presence of chromenes, a class of natural compounds that possess insecticidal properties. This study reports the effect of the hexane extract from the aerial parts of this plant on egg hatchability, egg production and mortality rates of newly hatched larvae of the cattle tick Boophilus microplus. Larvae of Rhipicephalus sanguineus, the brown dog tick, received the same treatment. The extract was toxic to the eggs of B. microplus and to the larvae of both B. microplus and R. sanguineus. 相似文献
93.
Terayama Y Kato H Gomez EA Uezato H Calvopiña M Iwata H Hashiguchi Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2008,70(9):907-913
Surveillance of the distribution of sand fly species is important for prediction of the risk and expansion of Leishmania infection in endemic and surrounding areas. In the present study, a simple and reliable method of typing New World Lutzomyia species circulating in endemic areas in Ecuador was established by using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique. PCR-RFLP of 18S ribosomal RNA (rRNA) genes with the restriction enzyme AfaI and subsequently HinfI successfully identified seven sand fly species in nine endemic areas in Ecuador. Although intraspecific genetic-diversity affecting the RFLP-patterns was detected in a species, the patterns were species specific. The method promises to be a powerful tool for the classification of New World Lutzomyia species. 相似文献
94.
Sarabia J Sánchez-Barbudo I Siqueira W Mateo R Rollán E Pizarrod M 《Avian diseases》2008,52(3):540-543
We describe lesions in 29 adult domestic pigeons (Columba livia) poisoned with chlorophacinone, an indandione anticoagulant rodenticide. Birds were found dead in the field and in dovecotes after a wide-area treatment against common voles (Microtus arvalis) based on the dispersion in the open field of wheat grain treated with 0.005% chlorophacinone. At necropsy, most pigeons showed crops full of red-colored wheat grain, extensive subcutaneous hematoma in neck and breast zones, and hemorrhages in lungs and the coelomic cavity. Chlorophacinone was determined in liver samples by high-performance liquid chromatography with ultraviolet detection, and the mean (range) concentration was 11.2 (1.48-50.1) microg/g. Pigeons have a venous subcutaneous plexus in the neck zone (plexus venosus subcutaneus collaris), which has been described as an erectile tissue with a thermoregulation function. This case report describes a relationship between the subcutaneous hemorrhagic lesions and the plexus venosus collaris. 相似文献
95.
96.
Sheila Rahal Ana Carolina Mortari Seizo Yamashita Miltom Morishin Filho Eduardo Hatschbac Júlio Lopes Sequeira 《The Canadian veterinary journal. La revue veterinaire canadienne》2008,49(9):871-876
Two cases of type 1 dermoid sinus in Rhodesian ridgebacks are described, with emphasis on the use of magnetic resonance imaging (MRI) in the diagnosis and delineation of the lesions. Magnetic resonance imaging was useful in identifying fluid-filled structures, fibrous capsules, and sinus tracts, but was not able to identify the termination of the tracts. 相似文献
97.
Picco EJ Rubio MR David DC Rodríguez C Boggio JC 《Veterinary research communications》2008,32(5):401-410
The aim of this work was to study the pharmacokinetic behaviour and the inhibitory effect on acetylcholinesterase and butyrylcholinesterase
activities of chlorpyrifos in male and female cattle after pour-on administration. Determination of cholinesterase activity
in plasma and erythrocyte was carried out according to Ellman kinetic method. The mean baseline activities were 9338.39 ± 1331.61
and 13220.69 ± 2274.18 to acetylcholinesterase and 624.65 ± 39.32 and 641.68 ± 88.08 IU/L to butyrylcholinesterase in females
and males, respectively. Acetylcholinesterase was the predominant form of cholinesterase analyzed, with low levels of butyrylcholinesterase.
The basal acetylcholinesterase activities of the bulls were significantly greater than those of cows. The inhibitory effect
of topical chlorpyrifos administration was lower on butyrylcholinesterase than on acetylcholinesterase. Chlorpyrifos peak
plasma concentration (male:10.920 ± 4.18; female:12.12 ± 3.88 μg/L) were reached at 11.92 ± 9.19 and 8.17 ± 7.67 h in male
and female, respectively. The values of area under curve were 185.96 ± 168.45 and 278.89 ± 270.00 μg·h/L and mean residence
time were 13.95 ± 8.10 and 14.90 ± 9.80 h in male and female, respectively. 相似文献
98.
99.
María Ortuo Maria S. Latrofa María A. Iborra Pedro Prez‐Cutillas Luis J. Bernal Jos Risueo Clara Muoz Ana Bernal Pedro F. Snchez‐Lopez Manuel Segovia Giada Annoscia Carla Maia Sofia Cortes Lenea Campino Domenico Otranto Eduardo Berriatua 《Zoonoses and public health》2019,66(8):961-973
Leishmania infantum causes human and canine leishmaniosis. The parasite, transmitted by phlebotomine sand flies, infects species other than dogs and people, including wildlife, although their role as reservoirs of infection remains unknown for most species. Molecular typing of parasites to investigate genetic variability and evolutionary proximity can help understand transmission cycles and designing control strategies. We investigated Leishmania DNA variability in kinetoplast (kDNA) and internal transcribed spacer 2 (ITS2) sequences in asymptomatically infected wildlife (n = 58) and symptomatically and asymptomatically infected humans (n = 38) and dogs (n = 15) from south‐east Spain, using single nucleotide polymorphisms (SNPs) and in silico restriction fragment length polymorphism (RFLP) analyses. All ITS2 sequences (n = 76) displayed a 99%–100% nucleotide identity with a L. infantum reference sequence, except one with a 98% identity to a reference Leishmania panamensis sequence, from an Ecuadorian patient. No heterogeneity was recorded in the 73 L. infantum ITS2 sequences except for one SNP in a human parasite sequence. In contrast, kDNA analysis of 44 L. infantum sequences revealed 11 SNP genotypes (nucleotide variability up to 4.3%) and four RFLP genotypes including B, F and newly described S and T genotypes. Genotype frequency was significantly greater in symptomatic compared to asymptomatic individuals. Both methods similarly grouped parasites as predominantly or exclusively found in humans, in dogs, in wildlife or in all three of them. Accordingly, the phylogenetic analysis of kDNA sequences revealed three main clusters, two as a paraphyletic human parasites clade and a third including dogs, people and wildlife parasites. Results suggest that Leishmania infantum genetics is complex even in small geographical areas and that, probably, several independent transmission cycles take place simultaneously including some connecting animals and humans. Investigating these transmission networks may be useful in understanding the transmission dynamics, infection risk and therefore in planning L. infantum control strategies. 相似文献
100.