全文获取类型
收费全文 | 2952篇 |
免费 | 237篇 |
国内免费 | 302篇 |
专业分类
林业 | 97篇 |
农学 | 259篇 |
基础科学 | 10篇 |
598篇 | |
综合类 | 1008篇 |
农作物 | 206篇 |
水产渔业 | 415篇 |
畜牧兽医 | 476篇 |
园艺 | 139篇 |
植物保护 | 283篇 |
出版年
2024年 | 14篇 |
2023年 | 47篇 |
2022年 | 84篇 |
2021年 | 108篇 |
2020年 | 143篇 |
2019年 | 134篇 |
2018年 | 109篇 |
2017年 | 180篇 |
2016年 | 197篇 |
2015年 | 172篇 |
2014年 | 153篇 |
2013年 | 192篇 |
2012年 | 234篇 |
2011年 | 246篇 |
2010年 | 190篇 |
2009年 | 185篇 |
2008年 | 168篇 |
2007年 | 185篇 |
2006年 | 140篇 |
2005年 | 105篇 |
2004年 | 91篇 |
2003年 | 62篇 |
2002年 | 56篇 |
2001年 | 47篇 |
2000年 | 38篇 |
1999年 | 29篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
排序方式: 共有3491条查询结果,搜索用时 156 毫秒
31.
Relationship between Polyamines and Other Cold‐induced Response Mechanisms in Different Cereal Species 下载免费PDF全文
O. K. Gondor G. Szalai V. Kovács T. Janda M. Pál 《Journal of Agronomy and Crop Science》2016,202(3):217-230
To find a connection between polyamines and various protective effectors involved in the development of cold tolerance, eight different cereal genotypes, including wheat, barley and oat species, were investigated during the acclimation phase to low temperature. Exposure to low temperature induced different changes in the levels of polyamines, and other signalling molecules, such as salicylic acid and abscisic acid, and of other protective compounds, namely flavonols, sugars and antioxidant enzyme activity, and in the lipid composition of certain membrane factions. The most remarkable differences were observed in the oat varieties compared to the other cereal genotypes, which was manifested in the lack of spermidine accumulation and of decrease in trans‐Δ3‐hexadecanoic acid content, in lower initial and not cold‐inducible abscisic acid content and guaiacol peroxidase activity after cold treatment. Correlation analysis revealed that spermidine shows strong positive relationship with flavonols, abscisic acid and ascorbate peroxidase, while was in negative relationship with trans‐Δ3‐hexadecanoic acid. These results suggest that spermidine may have a crucial role in the cold acclimation signalling processes in cereals. 相似文献
32.
Kjell Inge Reitan 《Aquaculture Research》2011,42(10):1530-1538
The digestion of laminaran and neutral lipids from the microalgae Chaetoceros muelleri or mixtures of C. muelleri and Isochrysis galbana clone T‐ISO in 4‐mm scallops Pecten maximus were studied. The microalgae were cultivated at fixed low and high growth rate (5% and 60% of μmax). The cultivation method clearly affected the lipid and carbohydrate contents, as well as their enzyme activity. Chaetoceros muelleri and T‐ISO grown at low growth rate exhibited a considerably higher content of lipids and carbohydrates than those algae grown at high growth rate. The specific activity of laminaranase and neutral lipase was the highest in C. muelleri grown at the low growth rate. Growth rate of scallops was best when they were fed a mono‐species diet of C. muelleri grown at low growth rate. The growth rate of the scallops was positively correlated to the dietary carbohydrate content as well as to the specific activity of neutral lipase and laminaranase in the diet. The capacity to digest carbohydrates (laminaran) might be limiting for the young scallops, and the content of carbohydrates and enzymatic activities of laminaran in the diet should be considered when formulating an optimal diet, both when the diet consist of live microalgae and formulated diets. 相似文献
33.
34.
35.
Alaa Elkomy Ali El-Hanoun Mohamed Abdella Karim El-Sabrout 《Journal of animal physiology and animal nutrition》2021,105(5):975-983
The aim of the present study was to investigate the long-term effect of using bee venom (BV) on the reproductive performance, immune, and health status of rabbit does and its effect on their litters. Sixty mature does, from Spanish V-line rabbit stock, were randomly assigned to four homogeneous groups with 15 does each. The 1st, 2nd and 3rd groups were injected twice weekly under the neck skin with 0.1 ml solution contains 0.1, 0.2 and 0.3 mg BV/rabbit respectively. The 4th group served as a control group. From the results, litter size at birth, litter weight and survival rate at weaning age as well as milk yield were significantly (p ≤ 0.05) increased in BV groups than in the control group. Serum estradiol 17-β (E2) was significantly (p ≤ 0.05) higher (15%) in the rabbit does treated with BV compared to the control group. The treated does with BV at any study doses showed a gradual and significant (p ≤ 0.05) decrease (12%) in serum progesterone levels (P4) compared to the control. They also showed a significant (p≤0.05) increase in conception (17%) and fertility rates (10%) compared to the control does. Treatment of rabbit does with BV caused a gradual and significant (p ≤ 0.05) reduction in both aspartate aminotransferase (AST) (16%) and alanine aminotransferase (ALT) (37%) liver enzyme activities. Additionally, results have shown that BV resulted in a gradual and significant (p ≤ 0.05) increase in total antioxidant capacity (TAC), antioxidative enzymes such as glutathione S-transferase (GST) and glutathione peroxidase (GPx), serum IgG, IgM and IgA levels with significant (p ≤ 0.05) decrease in malondialdehyde (MDA) and thiobarbituric acid reactive substances (TBARS) in BV groups compared to the control group. Results suggest that BV can be used in rabbit farming as an effective and safe alternative to artificial chemical drugs (sexual-stimulants) to improve certain reproductive traits, immune response and health. 相似文献
36.
本研究以甘草无菌苗为试验材料,采用植物组织培养的方法,分析50 mmol·L-1 NaHCO3 胁迫下外源海藻糖对甘草幼苗生长量、叶绿素含量、渗透调节物质含量、抗氧化保护酶活性和总黄酮含量的影响。结果表明: 50 mmol·L-1 NaHCO3 胁迫显著降低了甘草幼苗的生长量、叶绿体色素含量、K+ 浓度、抗氧化保护酶(SOD、POD、CAT)活性和总黄酮含量,显著提高了丙二醛、脯氨酸和可溶性糖含量以及Na+浓度;施加15 mmol·L-1 海藻糖可显著提高甘草幼苗的生长量,提高叶绿素含量、K+ 浓度和总黄酮含量,降低丙二酸含量、脯氨酸含量、可溶性糖含量和Na+ 浓度,并且提高抗氧化保护酶活性。因此,NaHCO3胁迫下施加外源海藻糖对甘草幼苗生长具有良好的调节作用,可以增强甘草的抗碱能力,促进甘草幼苗生长。本研究为外源海藻糖提高甘草耐碱性和揭示其调控机制提供理论依据。 相似文献
37.
The effects of transportation stress on Japanese quail (Coturnix Coturnix japonica) fed corn‐based diet in comparison with wheat‐based diet supplemented with xylanase and phytase 下载免费PDF全文
M. H. Mehraei Hamzekolaei A. K. Zamani Moghaddam S. S. Tohidifar A. Dehghani Samani A. Heydari 《Journal of animal physiology and animal nutrition》2016,100(4):618-622
Harvesting, handling and transporting quails to the slaughterhouses, other farms and laboratories might covertly reduce their welfare. The aim of this study was to evaluate the effects of two major sources of energy in poultry nutrition on reducing transportation stress in Japanese quail (Coturnix Coturnix japonica). Male quails (n = 60) were divided into two groups. The first group was fed corn‐based diet, and the second was fed wheat‐based diet supplemented with xylanase and phytase. At the end of the experiment (day 35), quails were subjected to 80 km of transportation. Immediately on arrival and after 24 h, heterophil counts, lymphocyte counts and H:L ratios were measured. On arrival, H counts were lower, L counts were higher, and H:L ratios were lower for corn‐fed group. After 24 h, wheat‐fed group showed lower increment of H counts, greater increment of L counts and also decrement of H:L ratios rather than corn‐fed group which showed increment of H:L ratios. However, these ratios were still lower in corn‐fed group. Results indicate that corn‐based diets can help Japanese quail to better resist transportation stress, although it seems that feeding wheat‐based diets supplemented with xylanase and phytase could have positive effects for coping better with stress after journeys. 相似文献
38.
39.
40.