全文获取类型
收费全文 | 387篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
林业 | 39篇 |
农学 | 22篇 |
基础科学 | 1篇 |
110篇 | |
综合类 | 16篇 |
农作物 | 63篇 |
水产渔业 | 43篇 |
畜牧兽医 | 82篇 |
园艺 | 8篇 |
植物保护 | 26篇 |
出版年
2022年 | 21篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 31篇 |
2016年 | 30篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 54篇 |
2012年 | 18篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 20篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有410条查询结果,搜索用时 15 毫秒
141.
This study was conducted to examine the compatibility between the Sarawak Forest Ordinance and Bidayuh Native Customary Laws in Sarawak and to gather the community members’ opinions on the compatibility of these laws. This study was carried out using two research methods, viz. a literature review and a survey among the Bidayuh community in Bau, Sarawak. The documents reviewed were the Forest Ordinance Chapter 126 (1958) and the Adat Bidayuh Order, 1994. There are several notable differences between the two laws in terms of, forest ownership, losing of rights to forest or inheritance, and the management of forest. A list of statements with six interval scales was presented and a majority of Bidayuh community members neither disagreed nor agreed with the statement, (1) Forest Ordinance respects the Bumiputera people’s rights (37.5 %; SD = 1.259) and (2) Forest Ordinance protects the Bumiputera people’s rights (37.5 %; SD = 1.281). The community members are also not sure about the consistency between these two laws (28.1 %; SD = 1.182). These results indicated the need for the State to respect the natives’ rights toward the forest land and its resources, recognize the Bidayuh Native Customary Laws and for the native people to learn about the constitutional provisions. Further studies are needed because the knowledge of Native Customary Law itself cannot guarantee the natives’ future in terms of economic, social and environmental aspects and there is also a need to review the current laws to achieve the objective to protect and preserve the natives’ rights. 相似文献
142.
143.
144.
Maryam Tabatabaei John B. Loomis Daniel W. McCollum 《Journal of Sustainable Forestry》2013,32(8):720-737
We estimated Colorado households’ nonmarket values for two forest management options for reducing intensity of future wildfires and associated nonmarket environmental effects wildfires. The first policy is the traditional harvesting of pine beetle-killed trees and burning of the slash piles of residual materials on-site. The second involves harvesting but moving the residual material off-site and converting it into biochar, thus reducing some of the risk and environmental effects associated with burning on-site. A contingent valuation method mail survey was used to evaluate these two management options. The survey achieved a 47% response rate. We used a nonparametric Turnbull estimator to calculate the willingness to pay (WTP) for burn on-site and off-site biochar conversion. The calculated WTP for burn on-site and off-site biochar conversion options (beyond the cost of the status quo level of forest treatment) is $411 and $470 per household per year, respectively. 相似文献
145.
The extracts of two Bangladeshi medicinal plants, Toona ciliata (stem bark) and Amoora rohituka (stem bark), along with siderin, a major coumarin from T. ciliata, exhibited significant in vitro antibacterial activity. The extracts also demonstrated mild antifungal effect. 相似文献
146.
Antimicrobial and cytotoxic constituents of Loranthus globosus 总被引:2,自引:0,他引:2
(+)-Catechin, 3,4-dimethoxycinnamyl alcohol and 3,4,5-trimethoxycinnamyl alcohol were isolated from the barks of Loranthus globosus. All compounds showed significant antimicrobial and cytotoxic activities. 相似文献
147.
Mohamad Hassanzadeh-Khayyat Maryam Akaberi Hamideh Moalemzadeh Haghighi Amirhossein Sahebkar Seyed Ahmad Emami 《林业研究》2019,(2):429-433
Epicuticular waxes have vital roles in the growth and development of plants and in defense. Conifers have a considerable amount of waxes on their cones and leaves.Here we characterized the n-alkane composition of Iranian conifers, including Juniperus oblonga, J. foetidissima, J.sabina, J. communis subsp. hemisphaerica, J. excelsa,Cupressus sempervirens, Platycladus orientalis from Cupressaceae and Taxus baccata from Taxaceae for the first time using GC-FID analyses. In the waxes, 25 n-alkane homologs with chain lengths ranging from C7 to C32 were identified. Short-chain n-alkanes were dominant in almost all samples with some exceptions. Complementary studies to elucidate complete wax constituents of Iranian conifers and n-alkane distribution pattern as a function of geographical and bioclimatic variables are recommended. 相似文献
148.
Impact of land-use management on nitrogen transformation in a mountain forest ecosystem in the north of Iran 总被引:2,自引:0,他引:2
Maryam Asadiyan Seyed Mohammad Hojjati Mohammad reza Pourmajidian Asghar fallah 《林业研究》2013,24(1):115-119
Soil inorganic N is one of the most important soil quality indexes, which may be influenced by land-use change. The historical conversion of land-use from native vegetation to agriculture resulted in sharp declines in soil N dynamics. This study was conducted to determine the soil inorganic N concentrations and net N mineralization rate in four common types of land-uses in the mountain forest area in the north of Iran, namely arable land, pine plantation, ash plantation, and beech stand. The soil samples were taken from top mineral soil layer (5cm) in each site randomly (n=6) during August- September 2010. Beech stand and ash plantation showed significantly higher total nitrogen compared with arable land and pine plantation, while extractable NH 4 + -N concentration was significantly greater in Beech stand compare to arable soils (p<0.05). No significantly difference was found in Net N mineralization, net nitrification and net ammonification rates among different land-uses. Results showed that net N mineralization and ammonification were occurred just in the soil of Ash plantation during the incubation time. Our findings suggested that conversion of Hyrcanian forests areas to pine plantation and agricultural land can disrupt soil natural activities and affect extremely soil quality. 相似文献
149.
150.
In greenhouse studies, corn (Zea mays L.) growth increased with Zn fertilization of two alkaline calcareous soils. Zinc concentration and total uptake increased with Zn application. Very high correlations were recorded between plant tissue Zn concentration, total Zn uptake and soil Zn levels determined by DTPA and AB-DTPA soil tests. Correlation between Zn concentration in plants and relative yield was poor. However, close relationships were revealed between extractable soil Zn and relative yield. Near maximum dry matter yield of corn was associated with a fertilizer rate of 2 mg Zn/kg soil. Plant tissue Zn-requirement was 27 mg/kg in 15 days old plants and 32 mg/kg in corn shoots of 40 day age. Critical soil test Zn level was 1.2 mg/kg by DTPA and 1.7 mg/kg by AB-DTPA method. Use of AB-DTPA soil test is suggested for evaluating Zn status of calcareous soils. 相似文献