全文获取类型
收费全文 | 131篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
林业 | 6篇 |
农学 | 1篇 |
基础科学 | 2篇 |
6篇 | |
综合类 | 34篇 |
农作物 | 1篇 |
水产渔业 | 2篇 |
畜牧兽医 | 91篇 |
园艺 | 2篇 |
植物保护 | 1篇 |
出版年
2021年 | 3篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1945年 | 1篇 |
1940年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1932年 | 1篇 |
1927年 | 1篇 |
1908年 | 1篇 |
1899年 | 1篇 |
排序方式: 共有146条查询结果,搜索用时 406 毫秒
41.
Hereditary cerebellar abiotrophy in Australian Kelpie dogs 总被引:1,自引:0,他引:1
42.
This study investigates what effect adding zinc to a final dietary concentration of 23.9 mg MJ−1 and/or linoleic acid to a dietary concentration of 3.6 g MJ−1 in a complete and balanced diet has on the skin and haircoat condition of adult dogs. All animals were fed for nine weeks on a standard diet followed by nine weeks on a supplemented diet. After each phase animals were quantitatively assessed with respect to the condition and function of their skin and coat. Dogs supplemented with the combination of zinc and linoleic acid showed a significant improvement in coat gloss ( P = 0.05) and coat scale ( P = 0.007) when compared to the control group of dogs receiving the standard diet. In addition dogs supplemented with either zinc alone or in combination with linoleic acid demonstrated a significant decrease ( P = 0.05) in transepidermal water loss over the time course of the test phase. As far as we are aware this is the first reported research to show that supplementation of a complete and balanced commercial dog food with zinc plus linoleic acid can make significant and substantial enhancements of the skin and coat condition in dogs. 相似文献
43.
JB Siqueira E Oba RO Pinho SEF Guimarães TM Neto JD Guimarães 《Reproduction in domestic animals》2014,49(5):851-857
The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls. 相似文献
44.
45.
46.
47.
Potential variation of nitrogen transformations in pinyon-juniper ecosystems resulting from burning 总被引:3,自引:0,他引:3
Summary Forest floor litter, duff, and underlying soils were assembled in laboratory microcosms representing pinyon, juniper, and interspace field conditions. Burning removed more than 95% of both N and C from the litter, with losses from the duff dependent on soil moisture conditions. No significant changes in total N or C were noted in the soil. Immediate increases were observed in soil NH
inf4
sup+
, decreasing with depth and related to soil heating. The greatest increases were noted in both the pinyon and juniper soils that were dry at the time of the burn, with interspace soils exhibiting the least changes. Soil NH
inf4
sup+
closely approximated the controls on day 90 after the burns in all treatments. Ninety days after the burn microbial biomass N was highest in the controls, followed by the wet and then the dry-burned soils, in both the pinyon and juniper microcosms. This was inversely related to the levels of accumulated NO
inf3
sup-
. Nitrifying bacteria populations were indirectly correlated to soil temperatures during the burn. Population levels 90 days after the burn showed increases in both the wet- and the dry-burn treatments, with those in the pinyon treatments exceeding those found in the nitial controls of pinyon soils.The use of trade and company names in this paper is for the benefit of the reader; such use does not constitute an official endorsement or approval of any service or product by the U.S. Department of Agriculture to the exclusion of others that may be suitable 相似文献
48.
Gloster J Williams P Doel C Esteves I Coe H Valarcher JF 《Veterinary journal (London, England : 1997)》2007,174(1):42-53
There is strong evidence to suggest that foot-and-mouth disease (FMD) can be transmitted by airborne virus up to many kilometres from a virus source. Atmospheric dispersion models are often used to predict where this disease might spread. This study investigated whether FMD virus (FMDV) aerosol has specific characteristics which need to be taken into consideration in these models. The characteristics and infectiousness of particles emitted by 12 pigs have been studied pre- and post-infection with O UKG 2001 FMDV. Aerosol generated by individual pigs was found log normally distributed in the range 0.015-20.0microm with concentrations between 1000 and 10000cm(-3) at the smallest size and <1cm(-3) above 10microm. No differences in either the total number of particles produced or their size distribution were detected between uninfected and infected pigs. However, a correlation between aerosol concentration and animal activity was found with a more active pig producing significantly greater concentrations than those that were less active. Viable virus was found up to a maximum of 6.3 log TCID(50)/24h/animal. The virus was distributed almost equally across the three size ranges; <3, 3-6 and >6microm. No correlation could be established between the production of virus and animal activity. In general the production of airborne virus closely followed the detection of viraemia in the blood and the presence of clinical symptoms. However, in one instance a pig excreted as much airborne virus as the other animals in the study, but with less virus detected in its blood. The results suggest that there is little merit in including a sophisticated virus release pattern based on physical activity periods or FMDV aerosol size spectrum, together with the appropriate dry deposition calculations, in models used to predict airborne spread of FMD. An estimate of the total daily virus production based on the clinical assessment of disease and virus strain is sufficient as input. 相似文献
49.
50.