全文获取类型
| 收费全文 | 587篇 |
| 免费 | 45篇 |
专业分类
| 林业 | 50篇 |
| 农学 | 27篇 |
| 107篇 | |
| 综合类 | 21篇 |
| 农作物 | 33篇 |
| 水产渔业 | 79篇 |
| 畜牧兽医 | 259篇 |
| 园艺 | 8篇 |
| 植物保护 | 48篇 |
出版年
| 2024年 | 2篇 |
| 2023年 | 12篇 |
| 2022年 | 20篇 |
| 2021年 | 42篇 |
| 2020年 | 36篇 |
| 2019年 | 42篇 |
| 2018年 | 41篇 |
| 2017年 | 35篇 |
| 2016年 | 32篇 |
| 2015年 | 27篇 |
| 2014年 | 34篇 |
| 2013年 | 32篇 |
| 2012年 | 41篇 |
| 2011年 | 45篇 |
| 2010年 | 17篇 |
| 2009年 | 17篇 |
| 2008年 | 27篇 |
| 2007年 | 31篇 |
| 2006年 | 23篇 |
| 2005年 | 11篇 |
| 2004年 | 11篇 |
| 2003年 | 10篇 |
| 2002年 | 12篇 |
| 2001年 | 8篇 |
| 2000年 | 4篇 |
| 1999年 | 2篇 |
| 1998年 | 1篇 |
| 1996年 | 3篇 |
| 1995年 | 1篇 |
| 1994年 | 4篇 |
| 1989年 | 1篇 |
| 1986年 | 2篇 |
| 1985年 | 1篇 |
| 1980年 | 2篇 |
| 1977年 | 1篇 |
| 1971年 | 2篇 |
排序方式： 共有632条查询结果，搜索用时 15 毫秒
1.
de Toledo Fábio Henrique S. F. de Moraes Gonçalves José Leonardo Mariño Yesid Alejandro de Vicente Ferraz Alexandre de Oliveira Ferreira Eric Victor Moreira Gabriela Gonçalves Hakamada Rodrigo de Arthur Júnior José Carlos 《New Forests》2020,51(3):469-488
Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha?1 of KCl compared with that of 2125 kg ha?1 of phonolite rock powder (equivalent to 170 kg ha?1 of K2O in both treatments); (2) application of 139 kg ha?1 of NaCl compared with that of 183 kg ha?1 of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.
相似文献2.
3.
4.
Carmen Klein Melanie Feist Gabriela Knubben-Schweizer Britta Dobenecker 《Journal of animal physiology and animal nutrition》2021,105(6):997-1001
High-yielding dairy cows collapsed and died displaying signs of a disturbed central nervous system (muscle tremor, convulsion) and a considerably reduced body condition score. An intense diagnostic screening did not allow to confirm a definite diagnosis. Therefore, further analyses including an evaluation of feeds and feeding were initiated. The herd was fed a total mixed ration (TMR) based on corn and grass silage of moderate nutritive value supplemented with various amounts of chocolate chips. In retrospect, the amount of chocolate chips added to the respective TMR batches could not be quantified. These chips were purchased from a company producing bakery and chocolate products for human consumption and added to the silage and therefore to the TMR in order to increase the energy intake of the animals. Because the TMR, which was fed during the time of the incidence, was no longer available, a sample of a later batch of silage was examined. The amount of chocolate chips was quantified (0.44% per fresh matter), and a theobromine analysis was performed in the chocolate chips of the available batch (69.7 mg/100 g fresh matter). Because of the possible link between chocolate intake and observed signs, an immediate cessation of using the chocolate chips was recommended in addition to an optimisation of the TMR, that is an increase of the energy density. Even though the theobromine intake during the time of the incidence is unknown and information about toxicity of theobromine in ruminants is limited, we suspect that the feeding of chocolate in this case caused all signs including the sudden death of the cows. Further reasons are that no differential diagnoses were established and the problems at the farm stopped after removing the chocolate from the TMR. 相似文献
5.
Aline Fernanda Lopes Paschoal Ana Paula Gonçalves Mellagi Cristina Vicenti Ferrari Karine Ludwig Takeuti Gabriela da Silva Oliveira Mari Lourdes Bernardi Rafael da Rosa Ulguim Fernando Pandolfo Bortolozzo 《Reproduction in domestic animals》2021,56(6):897-904
Semen collection has an essential role in the initial bacterial load in boar ejaculates and extended semen. The study aimed to explore the efficacy of an adjusted penis fixation in a semi-automatic collection system on reducing bacterial contamination of ejaculates in two-boar studs with different scenarios. Historically, stud A had low levels of bacterial load in raw semen, while stud B had a high level of contamination. A total of 56 mature boars had their semen collected using two methods of penis fixation: (a) Traditional: The penis was fixed directly with the artificial cervix and transferred to the adjustable clamp; (b) Adjusted: The fixation was performed with one gloved-hand, and after exteriorization, the penis was gripped using the artificial cervix with the other gloved-hand and transferred to the adjustable clamp. The bacterial load (p = .0045) and the occurrence of ejaculates >231 CFU/ml (p = .0101) were reduced in the Adjusted compared to the Traditional method. Bacterial load was reduced when using the Adjusted method in stud B (p = .0011), which showed a greater occurrence of critical factors for bacterial contamination (p ≤ .0034). The Adjusted method reduced the occurrence of ejaculates >231 CFU/ml when the preputial ostium was dirty (p = .016) and the duration of semen collection was >7 min (p = .022) compared to the Traditional method. In conclusion, the Adjusted penis fixation was efficient in reducing bacterial load of ejaculates, mainly in boar stud B, which had high contamination challenges. 相似文献
6.
7.
8.
9.
10.
A single-step duplex polymerase chain reaction (PCR) technique and traditional microscopic examination of haemolymph smears were used to detect Babesia bigemina and/or Babesia bovis infection in engorged female ticks of Boophilus microplus recovered from calves raised in an endemic area of the State of Minas Gerais, Brazil. In the PCR amplification of tick-derived DNA, pairs of oligonucleotide primers specific for a 278-bp sequence from B. bigemina and for a 350-bp sequence from B. bovis were used conjointly. The microscopic examination of haemolymph revealed that 16.7% of the engorged ticks were infected with Babesia spp., although no significant differences (rho > 0.05) were found in the infection rate of ticks collected from calves of different age groups. PCR analysis showed that 77.8% of the engorged ticks whose haemolymph contained sporokinetes were infected with B. bigemina, 7.8% with B. bovis and 14.4% with both protozoan species. However, the PCR assay further revealed that, amongst the engorged female ticks whose haemolymph was apparently negative for the presence of sporokinetes, 15.6% were infected with B. bigemina, 2.2% with B. bovis and 10.0% with both species. The duplex PCR method is thus more efficient and sensitive than the microscopic assay and also permits facile identification of the protozoa species present in engorged female ticks. 相似文献