全文获取类型
收费全文 | 14183篇 |
免费 | 940篇 |
国内免费 | 6篇 |
专业分类
林业 | 1175篇 |
农学 | 516篇 |
基础科学 | 98篇 |
3036篇 | |
综合类 | 575篇 |
农作物 | 564篇 |
水产渔业 | 1383篇 |
畜牧兽医 | 6220篇 |
园艺 | 249篇 |
植物保护 | 1313篇 |
出版年
2023年 | 101篇 |
2022年 | 137篇 |
2021年 | 309篇 |
2020年 | 302篇 |
2019年 | 274篇 |
2018年 | 609篇 |
2017年 | 598篇 |
2016年 | 586篇 |
2015年 | 438篇 |
2014年 | 562篇 |
2013年 | 791篇 |
2012年 | 932篇 |
2011年 | 884篇 |
2010年 | 501篇 |
2009年 | 525篇 |
2008年 | 744篇 |
2007年 | 718篇 |
2006年 | 585篇 |
2005年 | 607篇 |
2004年 | 504篇 |
2003年 | 451篇 |
2002年 | 414篇 |
2001年 | 320篇 |
2000年 | 314篇 |
1999年 | 259篇 |
1998年 | 80篇 |
1997年 | 52篇 |
1996年 | 62篇 |
1995年 | 54篇 |
1992年 | 145篇 |
1991年 | 125篇 |
1990年 | 125篇 |
1989年 | 140篇 |
1988年 | 125篇 |
1987年 | 135篇 |
1986年 | 119篇 |
1985年 | 113篇 |
1984年 | 89篇 |
1983年 | 81篇 |
1982年 | 52篇 |
1981年 | 61篇 |
1980年 | 55篇 |
1979年 | 106篇 |
1978年 | 94篇 |
1977年 | 84篇 |
1976年 | 56篇 |
1974年 | 101篇 |
1973年 | 73篇 |
1972年 | 95篇 |
1971年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Marek Šmejkal Marie Prchalová Martin Čech Mojmír Vašek Milan Říha Tomáš Jůza Petr Blabolil Jan Kubečka 《Ecology of Freshwater Fish》2014,23(3):405-413
Fish associations with different types of littoral habitats were studied in four canyon‐shaped reservoirs in the Czech Republic in years 2010 and 2011 by gillnets. Two to three habitats per reservoir–beaches (former meadows), stump fields (former forest) and rubble slopes–were defined and sampled along the longitudinal axis of reservoirs. Effects of reservoir, habitat and locality (position along longitudinal axis) on fish biomass, abundance and species structure were tested for juvenile and adult fish separately. Hierarchical analysis of variance revealed that habitats differed significantly in fish biomass and abundance. Redundancy analysis showed that analysed environmental variables had significant influence on fish community structure. Most variability in community structure was explained by reservoir and then by combination of habitat and slope steepness. Locality position had the smallest influence on community structure. For both adult and juvenile fish total abundance and biomass, the most inhabited habitat was beaches; rubble slopes were the least inhabited. Habitat associations differed among species. Among adults, bream Abramis brama, white bream Blicca bjoerkna and roach Rutilus rutilus were associated with beaches and stump fields, whereas perch Perca fluviatilis, ruffe Gymnocephalus cernuus, asp Aspius aspius and pike Esox lucius were associated with rubble slopes. Bream, white bream, bleak Alburnus alburnus, roach, ruffe and pikeperch Sander lucioperca were associated with beaches among juveniles, whereas the only juvenile associated with rubble slopes was perch. We showed that most common species are associated with distinct habitats and also that utilisation of various littoral habitats differs in general. 相似文献
92.
Robert Manuel L. Juárez-Gómez Juan Chaires-Pacheco Mariana Peña-Ramírez Yuri J. 《New Forests》2020,51(2):335-347
New Forests - Spanish red cedar, Cedrela odorata L. (Meliaceae), is a valuable timber tree in tropical American forests. Existing demand for elite individuals endangers the conservation of... 相似文献
93.
Carbonari Caio Antonio Gomes Giovanna Larissa Gimenes Cotrick Krenchinski Fábio Henrique Simões Plinio Saulo Batista de Castro Edicarlos Velini Edivaldo Domingues 《New Forests》2020,51(4):723-737
New Forests - Eucalyptus harvests generate residues that remain on the soil and affect the efficacy of preemergent herbicides in the following planting cycle. The objective of this work was to... 相似文献
94.
Santana Pedro Henrique Lopes Burak Diego Lang Thiengo Cássio Carlette Peçanha Anderson Lopes Neves Mirna Aparecida Mendonça Eduardo de Sá 《Journal of Soils and Sediments》2020,20(11):4103-4110
Journal of Soils and Sediments - After the greatest environmental disaster in the history of Brazil and the deposition of the iron ore tailings in alluvial regions, the process of revegetation for... 相似文献
95.
R. Vilcacundo D. Barrio C. Carpio A. García-Ruiz J. Rúales B. Hernández-Ledesma W. Carrillo 《Plant foods for human nutrition (Dordrecht, Netherlands)》2017,72(3):294-300
Quinoa protein concentrate (QPC) was extracted and digested under in vitro gastrointestinal conditions. The protein content of QPC was in the range between 52.40 and 65.01% depending on the assay used. Quinoa proteins were almost completely hydrolyzed by pepsin at pH of 1.2, 2.0, and 3.2. At high pH, only partial hydrolysis was observed. During the duodenal phase, no intact proteins were visible, indicating their susceptibility to the in vitro simulated digestive conditions. Zebrafish larvae model was used to evaluate the in vivo ability of gastrointestinal digests to inhibit lipid peroxidation. Gastric digestion at pH 1.2 showed the highest lipid peroxidation inhibition percentage (75.15%). The lipid peroxidation activity increased after the duodenal phase. The digest obtained at the end of the digestive process showed an inhibition percentage of 82.10%, comparable to that showed when using BHT as positive control (87.13%). 相似文献
96.
Survival and Growth Improvement of Palm Ruff,Seriolella violacea,Larvae Fed Artemia Nauplii Enriched with an Experimental Emulsion 下载免费PDF全文
Adens González Alfonso Silva Gonzalo Gajardo Claudio Martínez 《Journal of the World Aquaculture Society》2017,48(2):268-279
The palm ruff, Seriolella violacea (Cojinoba), is a potential new species for Chilean aquaculture. To approach Cojinoba larviculture, an experimental Artemia enrichment emulsion, containing docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) = 2.5, supplemented with vitamin E, astaxanthin, and β‐glucan, was evaluated in both Artemia and Cojinoba larvae, 30–50 d.a.h. This study tested an experimental enrichment emulsion versus a commercial emulsion, with an integral approach of multicompound emulsions. After 23 h enrichment, experimental emulsion (EE)‐enriched nauplii reached DHA and EPA concentrations of 23.8 and 18.7 mg/g dry weight (dwt), respectively, while in Cojinoba larvae they were 18.4 and 19.7 mg/g dwt. Control emulsion (CE)‐enriched nauplii exhibited lower DHA and EPA (6.1 and 7.7 mg/g dwt), while only DHA decreased in the control larvae (12.6 mg/g dwt). Vitamin E was higher in EE‐enriched nauplii (29.2 mg/100 g dwt) than in the control (8.4 mg/100 g dwt). Larvae fed EE‐enriched Artemia exhibited 8% increase in survival and 19% in growth compared with the control. Astaxanthin was detected only in larvae fed EE‐enriched nauplii. The tumor necrosis factor‐α concentration was not significantly different between larvae fed EE‐ and CE‐enriched nauplii. EE looks promising as an Artemia enrichment and experimental diet to assess palm ruff larval requirements, and has a positive impact on fish larvae performance. 相似文献
97.
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
98.
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
99.
Barrera-Reyes Paloma K de Lara Josué Cortés-Fernández González-Soto Melissa Tejero M Elizabeth 《Plant foods for human nutrition (Dordrecht, Netherlands)》2020,75(1):1-11
Plant Foods for Human Nutrition - The effects of cocoa-derived polyphenols on cognitive functions have been analyzed through numerous studies using different interventions (doses, vehicles, time... 相似文献
100.
New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)... 相似文献