全文获取类型
收费全文 | 234篇 |
免费 | 28篇 |
专业分类
林业 | 4篇 |
农学 | 2篇 |
基础科学 | 1篇 |
12篇 | |
综合类 | 32篇 |
农作物 | 7篇 |
水产渔业 | 22篇 |
畜牧兽医 | 171篇 |
园艺 | 1篇 |
植物保护 | 10篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 3篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 16篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有262条查询结果,搜索用时 15 毫秒
101.
102.
不同利用方式下草地土壤微生物及土壤呼吸特性 总被引:7,自引:0,他引:7
通过对呼伦贝尔羊草(Leymus chinensis)草甸草原土壤呼吸特性及土壤微生物的测定,研究了3种不同利用方式(围封、放牧和刈割)对天然草地土壤呼吸特性及土壤微生物的影响,为草甸草原土壤呼吸研究提供基础理论依据。结果表明:不同利用方式下土壤呼吸速率、土壤微生物量碳含量与土壤酶活性(除脲酶)均表现为草地围封比放牧和刈割呼吸速率高(含量高、活性强);土壤微生物量氮含量、脲酶活性和微生物数量表现为草地放牧和刈割比围封的含量高(活性强、数量多);土壤微生物量碳、氮含量、土壤酶活性(除脲酶)和土壤微生物数量均以表层(0~10cm)最高(活性最强、数量最多),随着土层深度增加而降低(活性下降、数量减少)。土壤呼吸速率与微生物量碳、土壤酶活性(除过氧化氢酶)成正相关,与微生物量氮、过氧化氢酶和微生物数量成负相关,其中只与微生物量氮相关性显著,而其余之间均不显著。 相似文献
103.
104.
Fabian A. Figueroa Roberto T. Abdala-Díaz Claudia Prez Virginia Casas-Arrojo Aleksandra Nesic Cecilia Tapia Carla Durn Oscar Valdes Carolina Parra Gastn Bravo-Arrepol Luis Soto Jos Becerra Gustavo Cabrera-Barjas 《Marine drugs》2022,20(7)
Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL−1 concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL−1. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource. 相似文献
105.
Book reviewed in this article:
Guide to the Dissection of Domestic Ruminants . RE Habel
Biology and Medicine of Rabbits and Rodents . JE Harkness and JF Wagner 相似文献
Guide to the Dissection of Domestic Ruminants . RE Habel
Biology and Medicine of Rabbits and Rodents . JE Harkness and JF Wagner 相似文献
106.
107.
Book reviewed in this article: Guide to the Dissection of Domestic Ruminants . RE Habel Biology and Medicine of Rabbits and Rodents . JE Harkness and JF Wagner 相似文献
108.
Budgerigars ( Melopsittacus undulatus ) from two different breeding colonies were found to have Giardia infection. Light microscopy, scanning electron microscopy and in-vitro and in-vivo studies confirmed the species was G psittaci . Chicks were clinically affected and showed signs of retarded growth, dehydration and diarrhoea. The faeces of adult birds treated with metronidazole in drinking water were negative for Giardia 5 days after treatment. Megabacteria were also found in adult birds but were not treated. This study extends the known host range for Giardia in Australia to include budgerigars. 相似文献
109.
110.
de Aluja A. S. Prez G. Tapia Lpez F. Pearson R. A. 《Tropical animal health and production》2005,37(1):159-171
Body measurements (length from nape of neck to the withers; height to withers; length from withers to tail root; length from shoulder to tuber ischii; thoracic circumference; umbilical circumference) were taken and correlated with live weight from 160 donkeys (mean ± standard deviation = 6 ± 2.6 years old) in Central México. The age was assessed from dentition. Sex of the donkeys was also recorded. Sex was an important factor of variation (p = 0.011). Live weight was estimated using two allometric models. Model 1: Live weight = β o × (thoracic circumference)β1. Model 2: Live weight = β o × (height to the withers) βl × (thoracic circumference) β2. Separate prediction equations were produced for males and females, plus one for the total sampled. The ‘best fit’ models, were those using thoracic circumference to predict the live weight. Males: live weight = 0.018576 × (thoracic circumference)1.84107 (R 2 = 0.9839). Females: live weight = 0.031255 × (thoracic circumference)1.72888 (R 2 = 0.9839). The equations derived to estimate the live weight of donkeys in Britain, Morocco and Zimbabwe were less satisfactory for use with donkeys from Central México because they overestimated the live weight. 相似文献