全文获取类型
收费全文 | 294篇 |
免费 | 21篇 |
国内免费 | 13篇 |
专业分类
林业 | 111篇 |
农学 | 18篇 |
基础科学 | 1篇 |
18篇 | |
综合类 | 84篇 |
农作物 | 22篇 |
水产渔业 | 3篇 |
畜牧兽医 | 67篇 |
园艺 | 2篇 |
植物保护 | 2篇 |
出版年
2022年 | 7篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 13篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 14篇 |
2012年 | 19篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 14篇 |
2007年 | 23篇 |
2006年 | 18篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有328条查询结果,搜索用时 343 毫秒
1.
为揭示木薯抗朱砂叶螨机理,以2个木薯品种‘新选048’和‘桂热4号’为材料,在朱砂叶螨发生危害时期,观察不同木薯品种受害程度并对其抗螨性进行鉴定,测定叶片单宁、可溶性糖、可溶性蛋白、游离脯氨酸及叶绿素的含量,分析各生理指标与朱砂叶螨危害程度的关系。结果表明,‘新选048’对朱砂叶螨的抗性优于‘桂热4号’。不同木薯品种,叶片单宁、可溶性糖、可溶性蛋白、游离脯氨酸及叶绿素含量不同;‘新选048’叶片单宁及叶绿素含量均高于‘桂热4号’,而可溶性蛋白、可溶性糖、游离脯氨酸含量则反之;螨害指数与单宁含量、叶绿素含量呈极显著负相关,与可溶性蛋白、可溶性糖、游离脯氨酸含量呈极显著正相关。木薯抗螨性与叶片中的可溶性糖、可溶性蛋白、游离脯氨酸、单宁、叶绿素含量密切相关,这些指标可作为木薯对朱砂叶螨抗性评价的主要指标。 相似文献
2.
ngela V. Egea María L. Bakker Liliana I. Allegretti Sebastin A. Paez Diego J. Grilli Juan C. Guevara Juan J. Villalba 《Grass and Forage Science》2019,74(1):115-128
We determined the seasonal nutrient and secondary compound intake, in vivo diet digestibility (DD) and diet species composition of goats in different physiological states in a desert rangeland of Argentina. During the wet and the dry seasons, 24 mature female Creole goats (six non‐lactating, non‐pregnant and six lactating in each season) were used in a 2 × 2 factorial design. Diet botanical composition, DD and dry‐matter intake (DMI) were estimated by the combined use of visual observation, microhistological analyses of faecal samples and n‐alkane technique. Browse species dominated the goats’ diets (>80%) in both seasons and physiological states, with a twofold increase in the proportion of forbs during the wet season (p < 0.10). Lactating goats showed greater DMI than non‐lactating animals, and they also displayed greater intakes of some tanniferous (Mimosa ephedroides) and high‐protein (Atriplex lampa) shrubs (p < 0.10). Lactating and non‐lactating goats selected diets with adequate crude protein (CP) and fibre content but insufficient energy, although lactating goats tended to increase energy and tannin content in their diets (p < 0.20). Physiological state did not influence DD, but digestibility was greater (p < 0.10) in the wet season, attributed to the greater protein content and lower tannin content of the diet. These results have important implications for managerial interventions on traditional goat production systems in the study area aiming at enhancing goat nutrition and welfare, as well as the sustainability of rangeland resources in the region. 相似文献
3.
4.
5.
通过对受拉缘蝽不同程度为害的卵叶小蜡叶片的单宁、黄酮、总酚含量的测定,结果表明:受害的卵叶小蜡叶片的单宁含量随着拉缘蝽若、成虫为害程度的加重而发生变化,在受害初期显著增加,但随着为害程度的加重,而呈逐渐下降的趋势;受害卵叶小蜡叶片中黄酮含量随着受害程度的加剧,呈先上升、而后再下降的特点;叶部总酚的含量随着受害程度的不断加重,总酚的含量呈现上升的趋势。说明卵叶小蜡应激反应的过程是一种随着受害程度的不同而不断变化的动态过程。 相似文献
6.
7.
8.
The willows Salix matsudana x alba and S. kinuyanagi, and the leguminous shrub Dorycnium rectum, are used for soil conservation in New Zealand and have potential value as browse plants. Two experiments were conducted in the lower North Island to ascertain the effect of selected establishment and cutting practices on their browse yield and nutritive value. A hill site experiment determined the effect of rooted and unrooted stem cuttings on establishment and initial production of the Salix species. A flat site experiment determined the effect of cutting height (0.10–0.30 m, 0.80 m, and 1.20 m above ground) and cutting frequency (once or twice per year) on yield of the Salix species and D. rectum. The establishment and dry matter (DM) yields of the Salix species were unaffected by the type of stem cutting. S. matsudana x alba (1.2 kg DM/tree) plants yielded more edible DM than S. kinuyanagi (0.9 kg DM/tree) and D. rectum (0.4 kg DM/tree). Cutting height had no effect on edible DM yield but affected total DM yield of the Salix species. Nitrogen concentration in edible DM, of all species, was 18–22 g/kg DM. In vitro organic matter digestibility of S. matsudana x alba (648–691 g/kg DM) and D. rectum (664–666 g/kg DM) was greater than S. kinuyanagi (611–615 g/kg DM). The condensed tannin concentration in edible DM of S. kinuyanagi was four-fold higher than in S. matsudana x alba (255 vs. 59 g/kg DM). It was concluded that S. matsudana x alba had the greatest potential as a browse species and D. rectum the least.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
9.
R. J. Kaitho I. V. Nsahlai B. A. Williams N. N. Umunna S. Tamminga J. van Bruchem 《Agroforestry Systems》1997,39(2):129-144
The aim of this work was to assess whether degradability, gas production or chemical constituents could predict the preference
of browses. Forty tropical browse species leaves with a crude protein (CP) content ranging from 79 to 307 g kg-1 DM were used for this study. The neutral detergent fibre (NDF) ranged from 220 to 694 g kg-1 DM, while acid detergent fibre (ADF) ranged from 146 to 523 g kg-1 DM. The NDF-bound nitrogen (NDFN) and ADF-bound nitrogen were particularly high in Calliandra calothyrsus, Acacia polyacantha,
Sesbania sesban, Acacia venosa and Acacia hockii. High levels of tannins were observed in Acacia species especially A. dolichocephala,
A. hockii, A. microbotrya and A. salicina. High levels were also observed in Flemingia macrophyla and Leucaena pallida. The
browse species differed (P < 0.05) in DM in sacco degradability coefficients. High potential degradability (PD) and effective
degradability (ED) were observed in Sesbania spp, Moringa stenopetala, Indigofera arrecta, Chamaecytisus palmensis and Atriplex
spp. The browses differed (P < 0.05) in asymptotic gas (Ag) production (ml g-1 OM), but had similar (P > 0.05) times of incubation at which half of the asymptotic gas had been formed. Preference and DM
intake were positively correlated (P < 0.01) to NDFN, but negatively correlated (P < 0.05) to NDF and ADF. The PD and Ag were
negatively (P < 0.001) related to NDF, ADF and lignin. Total phenols (TP) and condensed tannins (CT) were negatively (P <
0.05) related to PD, ED and Ag. A positive correlation was observed between CT and NDF-bound condensed tannins (r = 0.55,
P < 0.001) and, CT and TP (r = 0.40, P < 0.01). Prediction equations were poor for DM intake and preference, moderate for
gas production and good for potential and effective degradabilities. The phenolic components were more related to dry matter
degradation and gas production than to preference and dry matter intake. NDFN and Ag made a positive contribution to both
preference and DM intake. It was concluded that chemical constitutes such as N, NDF, NDFN, ADF and lignin are essential to
predict the nutritive value of browses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.