全文获取类型
收费全文 | 8305篇 |
免费 | 309篇 |
国内免费 | 309篇 |
专业分类
林业 | 1283篇 |
农学 | 652篇 |
基础科学 | 150篇 |
885篇 | |
综合类 | 2482篇 |
农作物 | 428篇 |
水产渔业 | 387篇 |
畜牧兽医 | 1017篇 |
园艺 | 1150篇 |
植物保护 | 489篇 |
出版年
2024年 | 109篇 |
2023年 | 284篇 |
2022年 | 334篇 |
2021年 | 253篇 |
2020年 | 338篇 |
2019年 | 399篇 |
2018年 | 280篇 |
2017年 | 316篇 |
2016年 | 272篇 |
2015年 | 318篇 |
2014年 | 352篇 |
2013年 | 472篇 |
2012年 | 502篇 |
2011年 | 391篇 |
2010年 | 315篇 |
2009年 | 508篇 |
2008年 | 320篇 |
2007年 | 272篇 |
2006年 | 205篇 |
2005年 | 171篇 |
2004年 | 347篇 |
2003年 | 157篇 |
2002年 | 211篇 |
2001年 | 165篇 |
2000年 | 205篇 |
1999年 | 108篇 |
1998年 | 92篇 |
1997年 | 89篇 |
1996年 | 243篇 |
1995年 | 151篇 |
1994年 | 133篇 |
1993年 | 100篇 |
1992年 | 95篇 |
1991年 | 62篇 |
1990年 | 59篇 |
1989年 | 33篇 |
1988年 | 49篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 22篇 |
1982年 | 18篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 32篇 |
1978年 | 16篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有8923条查询结果,搜索用时 15 毫秒
1.
Provision of feed supplies for the rapidly growing livestock population is essential in West Asia. Shortages can be alleviated by growing forage crops in the existing fallow lands.
Narbon vetch (Vicia narbonensis L.) is a leguminous species with high yield potential, drought tolerance and cold resistance. It could be used for grain and straw production as source for animal feed in dry areas. It is good source of protein with seeds contain 28 % protein yielding 364 kg per hectare protein, whilst straw contains 9 % protein and yields a similar amounts of digestible protein per hectare.
Nine promising lines of Narbon vetch developed at ICARDA were tested at two sites over four years under rainfed conditions. Since climatic conditions were considered to be of considerable importance, each site in each year was treated as a separate environment to give eight environments with annual rainfall varied from 195 to 504 mm.
Narbon vetch possessed high seedling vigour with rapid winter growth and negligible cold damage. Grain yield varied form 0.47 to 1.90 t/ha, with a harvest index varying from 30 to 40 %. The data indicated that below 300 mm rainfall the grain yield varied from 0.47 t/ha when rain fall was 195 mm to 1.4 t/ha when rainfall was 245 mm. Most of the lines had wide adaptation to dry areas in terms of both grain yield and stability. Climate, except early spring rains had little effect on biological and grain yields. 相似文献
Narbon vetch (Vicia narbonensis L.) is a leguminous species with high yield potential, drought tolerance and cold resistance. It could be used for grain and straw production as source for animal feed in dry areas. It is good source of protein with seeds contain 28 % protein yielding 364 kg per hectare protein, whilst straw contains 9 % protein and yields a similar amounts of digestible protein per hectare.
Nine promising lines of Narbon vetch developed at ICARDA were tested at two sites over four years under rainfed conditions. Since climatic conditions were considered to be of considerable importance, each site in each year was treated as a separate environment to give eight environments with annual rainfall varied from 195 to 504 mm.
Narbon vetch possessed high seedling vigour with rapid winter growth and negligible cold damage. Grain yield varied form 0.47 to 1.90 t/ha, with a harvest index varying from 30 to 40 %. The data indicated that below 300 mm rainfall the grain yield varied from 0.47 t/ha when rain fall was 195 mm to 1.4 t/ha when rainfall was 245 mm. Most of the lines had wide adaptation to dry areas in terms of both grain yield and stability. Climate, except early spring rains had little effect on biological and grain yields. 相似文献
2.
3.
M. Özgen 《Journal of Agronomy and Crop Science》1991,166(5):318-325
The purpose of this study was to compare responsiveness to environment as well as the stability of newly developed promising lines with traditional commercial cultivars. Subject research was conducted in Ankara between 1983-1989 on common and durum wheat cultivars and lines. Regression coefficient (b) was used as the criterion of genotypes' responsiveness to environment whereas deviation from regression (S2 d) and coefficient of determination (r2 ) were used as stability parameters. Each experiment year was regarded as an environment and yield average of each year was used as the environmental index.
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions. 相似文献
In consequence of the research, it was determined that new varieties with high yield, adaptable to diverse environments could be developed by means of hybridizations between parents having different genetic characteristics which were provided from diverse ecological regions. 相似文献
4.
5.
Minimal Set of Metabolic Pathways Suggested from the Genome of Onion Yellows Phytoplasma 总被引:1,自引:0,他引:1
6.
Kaolin treatment to reduce pomegranate sunburn 总被引:1,自引:0,他引:1
P. Melgarejo J. J. Martínez Fca Hernndez R. Martínez-Font P. Barrows A. Erez 《Scientia Horticulturae》2004,100(1-4):349-353
The aim of this study was to reduce pomegranate losses due to sunburn in south-western Spain. Summer temperatures may rise above 45 °C, resulting in sunburn damage to the fruits, which may inflict losses of up to 40% of the total yield. Data were obtained in two consecutive years. Surround® WP, a product comprising processed, refined kaolin, was sprayed over the whole canopy and fruits four times at 2–3-week intervals from mid-June to early August, the first application at 5% and the other three at 2.5%. The resulting white coating significantly reduced fruit and leaf surface temperatures relative to the control by averages of 4.9 and 2.5 °C, respectively. Sunburn damage of fruits was reduced from 21.9% in untreated control to 9.4% in the Surround WP-treated fruits. 相似文献
7.
通辽市主要有五大水系,湿地面积广阔。近年来由于人口的增加和社会经济的发 展,对湿地破坏严重,使得湿地面积锐减,湿地功能下降,湿地生态环境恶化。文章运用了遥 感、GIS技术对通辽市湿地进行分析研究,简略提出其保护措施。 相似文献
8.
9.
摘 要:选取放牧条件下体况良好、体重相近的甘南成年美仁公牦牛 6 头、母牦牛 4头进行屠宰,采取美仁牦牛肉的肩甲、背最长肌、股二头肌三个部位的分割肉。测定不同部位营养成分、氨基酸和脂肪酸。 结果显示:不同部位美仁牦牛肉的蛋白质含量为22.97%~23.07%,其中股二头肌蛋白质含量最低,背最长肌最高;脂肪含量为1.27%~2.49%,股二头肌脂肪脂肪含量较低,不足1.27%。氨基酸含量丰富,脂肪酸总量依次为肩甲、背最长肌、股二头肌上脑肉。通过对比分析不同部位美仁牦牛肉中营养成分、氨基酸和脂肪酸等含量存在差异。 相似文献
10.
ZHANG Yichuan LI Dongsheng WANG Shanshan School of L scape Architecture Henan Institute of Science Technology Xinxiang Henan China Forestry College Henan University of Science Technology Luoyang China 《东北农业大学学报(英文版)》2008,15(4):63-69
There has been a rapid development in the construction of wetland parks in China in recent years.This paper discussed the progress in the research of Chinese wetland parks that covered the aspects of wetland resources,landscape and environment.The function of wetland parks,the evaluation of landscape and the exploiting of resources;the landscape concept and landscape planning and design;the plant environment,the water environment and the recreation environment were all reviewed.The research of Chinese wetland parks started later but developed rapidly,having remarkable achievements in practice and functional studies,and there are still some shortcomings in the researches to be improved.At last,the key points which should be researched urgently in the future were discussed. 相似文献