全文获取类型
收费全文 | 10692篇 |
免费 | 866篇 |
国内免费 | 3篇 |
专业分类
林业 | 942篇 |
农学 | 429篇 |
基础科学 | 70篇 |
2808篇 | |
综合类 | 285篇 |
农作物 | 558篇 |
水产渔业 | 1161篇 |
畜牧兽医 | 4189篇 |
园艺 | 166篇 |
植物保护 | 953篇 |
出版年
2023年 | 100篇 |
2022年 | 154篇 |
2021年 | 301篇 |
2020年 | 303篇 |
2019年 | 279篇 |
2018年 | 581篇 |
2017年 | 552篇 |
2016年 | 577篇 |
2015年 | 416篇 |
2014年 | 481篇 |
2013年 | 688篇 |
2012年 | 826篇 |
2011年 | 750篇 |
2010年 | 443篇 |
2009年 | 359篇 |
2008年 | 594篇 |
2007年 | 596篇 |
2006年 | 485篇 |
2005年 | 451篇 |
2004年 | 402篇 |
2003年 | 355篇 |
2002年 | 287篇 |
2001年 | 218篇 |
2000年 | 219篇 |
1999年 | 187篇 |
1998年 | 40篇 |
1997年 | 44篇 |
1996年 | 32篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 19篇 |
1992年 | 55篇 |
1991年 | 43篇 |
1990年 | 41篇 |
1989年 | 48篇 |
1988年 | 38篇 |
1987年 | 40篇 |
1986年 | 47篇 |
1985年 | 50篇 |
1984年 | 37篇 |
1983年 | 35篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1979年 | 33篇 |
1978年 | 30篇 |
1977年 | 28篇 |
1974年 | 28篇 |
1973年 | 48篇 |
1972年 | 32篇 |
1971年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
171.
Ruiz-Matute AI Soria AC Martínez-Castro I Sanz ML 《Journal of agricultural and food chemistry》2007,55(18):7264-7269
Honey adulterations can be carried out by addition of inexpensive sugar syrups, such as high fructose corn syrup (HFCS) and inverted syrup (IS). Carbohydrate composition of 20 honey samples (16 nectar and 4 honeydew honeys) and 6 syrups has been studied by GC and GC-MS in order to detect differences between both sample groups. The presence of difructose anhydrides (DFAs) in these syrups is described for the first time in this paper; their proportions were dependent on the syrup type considered. As these compounds were not detected in any of the 20 honey samples analyzed, their presence in honey is proposed as a marker of adulteration. Detection of honey adulteration with HFCS and IS requires a previous enrichment step to remove major sugars (monosaccharides) and to preconcentrate DFAs. A new methodology based on yeast (Saccharomyces cerevisiae) treatment has been developed to allow the detection of DFAs in adulterated honeys in concentrations as low as 5% (w/w). 相似文献
172.
Morlin Carneiro Franciele Angeli Furlani Carlos Eduardo Zerbato Cristiano Candida de Menezes Patricia da Silva Gírio Lucas Augusto Freire de Oliveira Mailson 《Precision Agriculture》2020,21(5):979-1007
Precision Agriculture - Crop monitoring through remote sensing techniques enable greater knowledge of average variability in crop growth. Canopy sensors help provide information on the variability... 相似文献
173.
David M. Jaramillo José C. B. Dubeux Jr Joao M. B. Vendramini Luana M. D. Queiroz Erick R. S. Santos Martin Ruiz-Moreno Liza Garcia Daciele Sousa de Abreu Lucas Ramos de Miranda Michelle Cristina Fernando de Siqueira 《Grass and Forage Science》2020,75(2):153-158
Nitrogen fertilization is a common practice for sustaining forage production in forage systems in southeastern United States. Warm-season annual legumes may be an alternative forage to warm-season perennial grasses that do not require N fertilization. Sunn hemp (Crotalaria juncea L.) is a fast-growing, warm-season annual legume native to India and Pakistan. The objective of this 2-year study was to assess the herbage accumulation (HA), atmospheric N2 fixation (ANF) and nutritive value of sunn hemp. Treatments were the factorial arrangement of two sunn hemp cultivars (“Crescent Sun” and “Blue Leaf”), three seeding rates (17, 28 and 39 kg seed/ha) and seed inoculation (inoculated or non-inoculated seeds), distributed in a randomized complete block design with four replicates. Crescent sun had greater HA (3,218 vs. 1764 kg DM/ha) and ANF (41 vs. 25 kg N/ha). Blue leaf had greater crude protein (CP) (188 vs. 176 g/kg) and in vitro digestible organic matter (IVDOM) concentrations (564 vs. 531 g/kg) than crescent sun. Non-inoculated seed had greater CP than inoculated seed, 188 and 177 g/kg, respectively, and inoculation did not affect HA. Intermediate seeding rate (28 kg/ha) decreased HA (2002 kg DM/ha), while HA from high and low seeding rates (17 and 39 kg/ha, respectively) did not differ (2,863 and 2,615 kg DM/ha respectively). Planting non-inoculated crescent sun at 17 kg/ha seeding rate is a feasible management practice to produce sunn hemp in subtropical regions; however, inoculation should always be recommended for proper establishment. 相似文献
174.
Alyce Raiana Monteiro dos Santos Lívia Vieira de Barros Matheus Lima Côrrea Abreu Bruno C. Pedreira 《Grass and Forage Science》2020,75(3):339-350
The addition of protein supplementation in a silvopastoral system can contribute to improved forage intake and digestibility. Our objective was to evaluate in vitro ruminal parameters, digestibility and gas production of Marandu palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster] in a silvopastoral system and compare this to parameters obtained from diets with protein supplementation. Forage was sampled during the growing season (November to April) in 2016/17 and 2017/18. In vitro incubation treatments consisted of four levels of protein supplement (20% of crude protein; CP) in the diet (0.1, 0.2, 0.3 and 0.4 g/kg of body weight). The neutral detergent fibre, acid detergent fibre and indigestible neutral detergent fibre concentrations were highest in the first year. In the second year, CP concentration was 21% greater than in the first year. There was a linear increase for digestion rate, a quadratic effect for lag time and a linear decrease for average digestion time as supplementation levels were increased. The least lag time and digestion time occurred in the second year. There was no supplementation effect on ruminal pH, acetate and butyrate concentrations. Second-year in vitro dry matter digestibility (IVDMD) was greater than in the first year. Increases in supplementation levels linearly enhanced IVDMD and reduced methane (CH4) production. The inclusion of a protein supplement contributed to reduced CH4 and increased volatile fatty acids production; therefore, we recommended the supplement inclusion of >0.28 g/kg of BW for animals grazing in well-managed palisadegrass pastures. 相似文献
175.
Fagner Junior Gomes Bruno Carneiro Pedreira Patrícia Menezes Santos Cristiam Bosi Carlos Guilherme Silveira Pedreira 《Grass and Forage Science》2020,75(3):279-290
In silvopastoral (SP) systems, forage responses depend on the microenvironment in which the plants develop. Our objective was to evaluate canopy and tillering characteristics of shaded 'Marandu' palisadegrass [Brachiaria brizantha (Hochst A Rich) Stapf, syn. Urochloa brizantha] under continuous stocking in a SP system. Treatments were one full sun (FS) and three shaded systems (silvopasture, SP) corresponding to distances from tree groves: 7.5 m north (SP1), and 15 m (SP2) and 7.5 m south (SP3) studied during two rainy seasons (Year 1 and Year 2). The tree in the SP system was Eucalyptus urograndis (hybrid of Eucalyptus grandis W. Hill ex Maiden × Eucalyptus urophylla S. T. Blake). The photosynthetic active radiation was greater in FS (923 μmol m-2 s-1), followed by SP2 (811 μmol m-2 s-1), SP1 (727 μmol m-2 s-1) and SP3 (673 μmol m-2 s-1). Forage accumulation in FS was 15% greater than the mean of SP1, SP2 and SP3 (10,663 kg DM/ha). There was no difference in net accumulation of leaf, stem and dead material, averaging 3,302, 3,420 and 4,063 kg DM/ha respectively. Leaf accumulation and accumulation rate were greater in Year 2, and leaf accumulation rate was similar among treatments (19 kg DM ha−1 day−1). Leaf proportion increased 14% from Year 1 to Year 2. Specific leaf area was greater for treatments SP1 and SP3 (193 cm2/g). Tiller population density was similar across treatments in Year 1. Shaded palisadegrass maintains leaf productivity similar to FS under continuous stocking in an SP system. 相似文献
176.
Řebíčková Kristýna Bajer Tomáš Šilha David Ventura Karel Bajerová Petra 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(4):495-504
Plant Foods for Human Nutrition - The purpose of this study was to compare the yield, chemical composition, antimicrobial and antioxidant properties of essential oils isolated from leaves of Laurus... 相似文献
177.
Villacrés Elena Cueva Paúl Díaz Milene Rosell Cristina M. 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(4):569-575
Plant Foods for Human Nutrition - In this study the breadmaking potential of lupin flour from L. mutabilis after being debittered (DLF) and solid state fermented (FLF) was evaluated in lupin-wheat... 相似文献
178.
Faridy Juárez-Chairez Milagros Stephanie Cid-Gallegos María Gabriela Meza-Márquez Ofelia Cristian Jiménez-Martínez 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(2):142-153
Plant Foods for Human Nutrition - Chickpea is one of the most consumed legumes worldwide. Among their benefits are the high protein concentration that reflects not only at the nutritional level but... 相似文献
179.
Palavecino Pablo Martín Curti María Isabel Bustos Mariela Cecilia Penci María Cecilia Ribotta Pablo Daniel 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(3):326-336
Plant Foods for Human Nutrition - Sorghum is a major cereal crop with various agronomic advantages, contains health-promoting compounds and is gluten-free. There is a growing tendency to use... 相似文献
180.