全文获取类型
收费全文 | 419篇 |
免费 | 21篇 |
专业分类
林业 | 15篇 |
农学 | 2篇 |
基础科学 | 1篇 |
42篇 | |
综合类 | 77篇 |
农作物 | 9篇 |
水产渔业 | 36篇 |
畜牧兽医 | 242篇 |
园艺 | 1篇 |
植物保护 | 15篇 |
出版年
2019年 | 5篇 |
2018年 | 6篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2010年 | 5篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 17篇 |
2005年 | 20篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 10篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1997年 | 4篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1971年 | 8篇 |
1970年 | 4篇 |
1968年 | 5篇 |
1967年 | 5篇 |
1963年 | 5篇 |
1960年 | 4篇 |
1940年 | 3篇 |
1939年 | 3篇 |
1938年 | 5篇 |
1936年 | 4篇 |
排序方式: 共有440条查询结果,搜索用时 15 毫秒
21.
Cryptosporidiosis in the domestic cat 总被引:2,自引:0,他引:2
M Bennett D Baxby N Blundell C J Gaskell C A Hart D F Kelly 《The Veterinary record》1985,116(3):73-74
22.
S P Hart 《Journal of animal science》1990,68(11):3832-3842
The effects of increasing grain content of sorghum silage at the soft dough or the mature stages on nutrient digestibility, rate of passage and ruminal characteristics were investigated. A hetero-yellow grain sorghum (WAC 710DR) was harvested at the soft dough and the mature stage. Conventional sorghum silage was harvested by harvesting only the material more than 12 cm above the ground, high-energy silage by cutting it at a 40-cm height and headchop by harvesting at a 65-cm height. Regular silage was supplemented with either 17% or 34% grain to provide amounts of grain equal to that in the high-energy silage and headchop; high-energy silage was supplemented with 25% grain to equal the grain content of headchop. Diets were supplemented to 11.0% CP with soybean meal. Grain content was greater for headchop than for regular silage (72% vs 53%) but DM yield was lower (2,900 vs 4,600 kg/ha). Silages harvested at the more mature stage had lower digestibility of DM (62 vs 68%), CP (60 vs 64%), NDF (46 vs 50%), ADF (48 vs 52%) and starch (89 vs 97%). Increasing the height of cut did not increase DM digestibility of the silage. Compared with conventional silage, headchop had depressed NDF (43 vs 51%) and ADF (46 vs 55%) digestibility. Supplementation of silages with grain did not increase digestibility. The failure to increase DM digestibility was not due to depressed fiber or starch digestion, but rather to an increased fecal excretion of cell contents. The digestibility of grain sorghum silage was not improved by increasing the height of cut or adding supplemental grain. 相似文献
23.
24.
25.
The activity and inhibition of poly(ADP‐ribose) polymerase‐1 in equine peripheral blood mononuclear cells in vitro 下载免费PDF全文
26.
Lerat S Gulden RH Hart MM Powell JR England LS Pauls KP Swanton CJ Klironomos JN Trevors JT 《Journal of agricultural and food chemistry》2007,55(25):10226-10231
The presence of the recombinant cp4 epsps gene from Roundup Ready (RR) corn and RR soybean was quantified using real-time PCR in soil samples from a field experiment growing RR and conventional corn and soybean in rotation. RR corn and RR soybean cp4 epsps persisted in soil for up to 1 year after seeding. The concentration of recombinant DNA in soil peaked in July and August in RR corn and RR soybean plots, respectively. A small fraction of soil samples from plots seeded with conventional crops contained recombinant DNA, suggesting transgene dispersal by means of natural process or agricultural practices. This research will aid in the understanding of the persistence of recombinant DNA in agricultural cropping systems. 相似文献
27.
28.
Blaise Ratcliffe Foster J. Hart Jaroslav Klápště Barry Jaquish Shawn D. Mansfield Yousry A. El-Kassaby 《Annals of Forest Science》2014,71(3):415-424
Context
Wood quality traits are important to balance the negative decline of wood quality associated with selection for growth attributes in gymnosperm breeding programs. Obtaining wood quality estimates quickly is crucial for successful incorporation in breeding programs.Aims
The aims of this paper are to: (1) Estimate genetic and phenotypic correlations between growth and wood quality attributes, (2) Estimate heritability of the studied traits, and (3) Assess the accuracy of in situ non-destructive tools as a representative of actual wood density.Methods
Wood density (X-ray densitometry), tree height, diameter, volume, resistance drilling, acoustic velocity, and dynamic modulus of elasticity were estimated, along with their genetic parameters, for 1,200, 20-year-old trees from 25 open-pollinated families.Results
Individual tree level heritabilities for non-destructive evaluation attributes were moderate ( $ {\widehat{h}}_i^2=0.37-0.42 $ ), wood density and growth traits were lower ( $ {\widehat{h}}_i^2=0.23-0.35 $ ). Favorable genetic and phenotypic correlations between growth traits, wood density, and non-destructive evaluation traits were observed. A perfect genetic correlation was found between resistance drilling and wood density (r G ?=?1.00?±?0.07), while acoustic velocity and dynamic modulus of elasticity showed weaker genetic correlations with wood density (r G ?=?0.25?±?0.24;?0.46?±?0.21, respectively).Conclusion
This study confirmed that resistance drilling is a reliable predictor of wood density in western larch, while the weak genetic correlations displayed by acoustic velocity and dynamic modulus of elasticity suggest limited dependability for their use as fast in situ wood density assessment methods in this species. 相似文献29.
Arthur J. Ritar Greg G. Smith Graeme A. Dunstan Malcolm R. Brown Piers R. Hart 《Aquaculture International》2003,11(1-2):163-182
Performance of phyllosoma of thesouthern rock lobster (Jasus edwardsii)was examined after feeding Artemia-baseddiets. Survival and growth of newly-hatchedlarvae cultured to Stage III were lower(p < 0.05) when fed 0.8 mm Artemia than1.5 mm or 2.5 mm Artemia alone or 1.5 mmArtemia in combination with pieces ofmussel (Mytilus edulis planulatus) gonad.This could not be attributed to deficiencies inthe composition of fatty acids but appeared tobe due to the inability of larvae to capturesufficient appropriate-sized, enrichedArtemia for their nutritional requirements.There was an indication that survival andgrowth were higher between Stages III and Vwhen fed 2.5 mm Artemia than 1.5 mmArtemia alone or in combination with musselpieces. However, Stage VI larvae grew to asimilar size at Stage VIII when fed 1.5 mm or2.5 mm Artemia. Unexpectedly, larvae fedthe combination of 1.5 mm Artemia plusmussel supplement had lower survival than foundpreviously, and generally lower than when fed 1.5 mm Artemia alone. This was despitean apparent nutritional profile (lipid contentand fatty acid composition) of mussel more akinto that of newly-hatched phyllosoma thanenriched Artemia. On the other hand,survival and growth to Stage VIII were higherwhen larvae were fed alginate pelletscontaining Artemia than when fed 1.5 mmor 2.5 mm Artemia alone. 相似文献
30.
The effects of kin and familiarity on interactions between fish 总被引:8,自引:0,他引:8
Fish have been shown to discriminate between individuals on very general bases such as species, body length and colour. More recently, evidence has been accumulating from a number of species that relatedness and familiarity may be extremely important in mediating a range of interactions between individual fish. Studies have shown that fish are able to recognize kin and/or familiars, and that this ability potentially conveys significant benefits, including increased inclusive fitness, reduced inbreeding costs, reduced competition and enhanced antipredator behaviour. Here, we review the literature and consider future directions and applications for this research. 相似文献