全文获取类型
收费全文 | 1067篇 |
免费 | 74篇 |
专业分类
林业 | 55篇 |
农学 | 26篇 |
基础科学 | 4篇 |
327篇 | |
综合类 | 45篇 |
农作物 | 74篇 |
水产渔业 | 84篇 |
畜牧兽医 | 456篇 |
园艺 | 25篇 |
植物保护 | 45篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 24篇 |
2020年 | 28篇 |
2019年 | 29篇 |
2018年 | 48篇 |
2017年 | 40篇 |
2016年 | 52篇 |
2015年 | 35篇 |
2014年 | 50篇 |
2013年 | 68篇 |
2012年 | 66篇 |
2011年 | 82篇 |
2010年 | 49篇 |
2009年 | 52篇 |
2008年 | 60篇 |
2007年 | 49篇 |
2006年 | 59篇 |
2005年 | 45篇 |
2004年 | 42篇 |
2003年 | 24篇 |
2002年 | 33篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 16篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 10篇 |
1983年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1963年 | 1篇 |
1928年 | 3篇 |
1926年 | 1篇 |
1925年 | 1篇 |
1924年 | 4篇 |
1913年 | 1篇 |
1912年 | 1篇 |
1910年 | 1篇 |
1905年 | 1篇 |
1903年 | 1篇 |
排序方式: 共有1141条查询结果,搜索用时 0 毫秒
31.
Milena W. Ferreira Felipe G. de Araujo Diego V. Costa Priscila V. Rosa Henrique C. P. Figueiredo Luis D. S. Murgas 《Journal of the World Aquaculture Society》2011,42(1):24-33
To investigate the impact of different dietary lipid sources on fillet composition and lipid transport, we conducted a feeding trial and evaluated the proximate composition of muscle tissue, fatty acid profiles, total cholesterol (in muscle and plasma), triglycerides, and lipoprotein concentrations in Nile tilapia, Oreochromis niloticus. Five semi‐purified diets, containing different oils (soybean – SO, corn – CO, linseed – LO, fish – FO, and olive – OO), were supplied to tilapia for 160 d. Fish fed with LO and FO diets had a lower percentage of total lipids in muscle compared with the others (P < 0.05). The highest percentage of protein was found in fish fed with FO diet (P < 0.05). The muscle fatty acid profile was influenced differently by diets (P < 0.05). The group supplemented with SO and CO had a higher concentration of 18:2n‐6, whereas the fish fed with LO diet had a higher level of 18:3n‐3 and those that received the FO diet had more 22:6n‐3 in comparison with those supplemented with vegetable oils. Plasma lipid transport was also affected by the diets: the fish fed with FO diet had higher total cholesterol and high‐density lipoprotein and lower very‐low‐density lipoprotein concentrations (P < 0.05). 相似文献
32.
33.
34.
Renata Pereira da Silva-Marques Joanis Tilemahos Zervoudakis Nelcino Francisco De Paula Luciana Keiko Hatamoto-Zervoudakis Pedro Ivo José Lopes da Rosa e Silva Núbia Bezerra do Nascimento Matos 《Tropical animal health and production》2018,50(3):495-501
Two experiments were conducted to evaluate reduced supplementation frequencies for grazing beef cattle in rainy season. In experiment 1, evaluating the nutritional parameters, four rumen-cannulated Nellore bulls (BW = 410 kg) were used. In experiment 2, evaluating animal performance, 48 Nellore bulls (BW = 358 kg) were used. The treatments were as follows: mineral supplement (MS) alone and MS plus protein-energy supplement provided 3×, 5× and 7×/week. Supplementation frequency did not affect (P > 0.05) intake and digestibility. Average daily gain was greater (P < 0.001) to supplementation compared with MS. The supplementation 5×/week resulted in greater weight gain per hectare (9.24) and higher economic returns during the study period (1.64%) compared to other supplementations. Supplementation 5×/week increased animal performance and positively influenced economic returns. 相似文献
35.
Sandro Froehner Daniele Botelho Souza Karina Scurupa Machado Edson Cordova da Rosa 《Water, air, and soil pollution》2010,210(1-4):33-41
The Barigüi River watershed is located in the metropolitan region of Curitiba, Southern Brazil, passing through several neighboring counties. In recent years, due to growth and disorderly occupation along the river, in addition to lack of sanitation, the Barigüi River suffered a very large inflow of untreated domestic wastewater. Current programs to monitor the watershed use traditional physical–chemical parameters. Here, the presence of some molecular tracers found in domestic effluents was investigated, such as caffeine and coprostanol at some selected sites in Barigüi River. Caffeine is highly soluble in water and its presence in water bodies is due to the disposal of untreated sewage. Caffeine is eliminated in the urine (approximately 0.5% to 10% of the consumption). The samples were collected in three campaigns, two in dry weather and another during a week in the rainy season. The results showed that caffeine concentration ranged between zero and 753.5 μg g?1. Higher values were found on rainy days. Caffeine showed a positive correlation between BOD and nitrate; it also showed a positive correlation with coprostanol, a fecal biomarker. Finally, caffeine has been shown to be a good parameter to determine the contamination by domestic wastewater. 相似文献
36.
Bennett RN Mellon FA Rosa EA Perkins L Kroon PA 《Journal of agricultural and food chemistry》2004,52(19):5856-5862
Azima tetracantha L. (needle bush; bee sting bush; Salvadoraceae) is used as a food and for various herbal medicines in Africa, India, and Madagascar, but there is very little information on the secondary metabolites in this species. High concentrations of N-methoxy-3-indolylmethyl-glucosinolate, a common glucosinolate of Brassica crops such as Brussels sprouts and broccoli, were found in the roots and seeds of A. tetracantha. Lower concentrations were detected in the stems and young leaves. The roots also contained another indole glucosinolate that was provisionally identified, from MS data and comparison with indole glucosinolate standards, as N-hydroxy-3-indolymethyl-glucosinolate. The roots, stems, and leaves contained neoascorbigen (the condensation product of N-methoxy-indole-3-carbinol and ascorbic acid). The seeds of A. tetracantha contained a complex mixture of 26 flavonoids predominantly as glycosides and acyl-glycosides, with traces of aglycones. The core aglycones of these flavonoids were identified as quercetin, isorhamnetin (3'-O-methylquercetin), rhamnetin (7-O-methylquercetin), and rhamnazin (7, 3'-di-O-methylquercetin). No flavonoids or anthocyanins were detected in other tissues, and procyanidins were undetectable. The dimeric piperidine alkaloids azimine, azcarpine, and carpaine were found in all tissues of A. tetracantha. 相似文献
37.
38.
Rodrigues VM Rosa PT Marques MO Petenate AJ Meireles MA 《Journal of agricultural and food chemistry》2003,51(6):1518-1523
Supercritical fluid extraction (SFE) from aniseed using carbon dioxide was performed at 30 degrees C and pressures of 80-180 bar. The chemical composition of the SFE extract was determined by GC-MS; the quantitative analysis was done by GC-FID and TLC. The total amount of extractable substances or global yield (mass of extract/mass of feed) for the SFE process varied from 3.13 to 10.67% (mass). The solubilities of the anise essential oil in CO(2) were 0.0110, 0.0277, 0.0143, and 0.0182 kg of solute/kg of CO(2) at 80, 100, 140, and 180 bar, respectively. The major compounds identified and quantified in the extracts were anethole ( approximately 90%), gamma-himachalene (2-4%), p-anisaldehyde (<1%), methylchavicol (0.9-1.5%), cis-pseudoisoeugenyl 2-methylbutyrate ( approximately 3%), and trans-pseudoisoeugenyl 2-methylbutyrate ( approximately 1.3%). The Sovová model described quite well the experimental overall extraction curves. 相似文献
39.
Henrique de Souza Luche José Antonio Gonzalez da Silva Rafael Nornberg Emilio Ghisleni Arenhardt Vanderlei da Rosa Caetano Luciano Carlos da Maia Antonio Costa de Oliveira 《Journal of Crop Science and Biotechnology》2017,20(2):73-80
In wheat, the increase of yield and stability associated traits can be achieved by combining parents containing the stay-green trait and favorable alleles for grain yield. The aim of this work was to analyze the genetic dissimilarity between wheat lines from stay-green and synchronized maturation groups and elite cultivars. Moreover, to propose promising combinations seeking the selection of high-grain yield and high bread-making quality genotypes containing stay-green trait. The experiment was conducted in a randomized block design with three replications in 2003, 2004, and 2005, using sister-lines with the presence and absence of stay-green trait and elite cultivars. Genetic variability exists among wheat strains from the synchronized stay-green maturation group and elite cultivars. Genotypes of maturation group stay-green obtained an average performance superior to the synchronized group. Crosses between stay-green lines and the CEP 29 and BRS 177 cultivars are promising in the selection of genotypes carrying the stay-green trait with high yield and bread-making quality. 相似文献