全文获取类型
收费全文 | 4169篇 |
免费 | 65篇 |
国内免费 | 1篇 |
专业分类
林业 | 333篇 |
农学 | 84篇 |
基础科学 | 18篇 |
687篇 | |
综合类 | 647篇 |
农作物 | 170篇 |
水产渔业 | 380篇 |
畜牧兽医 | 1530篇 |
园艺 | 120篇 |
植物保护 | 266篇 |
出版年
2024年 | 43篇 |
2023年 | 45篇 |
2022年 | 69篇 |
2021年 | 106篇 |
2020年 | 139篇 |
2019年 | 161篇 |
2018年 | 149篇 |
2017年 | 117篇 |
2016年 | 137篇 |
2015年 | 94篇 |
2014年 | 142篇 |
2013年 | 202篇 |
2012年 | 263篇 |
2011年 | 324篇 |
2010年 | 170篇 |
2009年 | 156篇 |
2008年 | 261篇 |
2007年 | 266篇 |
2006年 | 224篇 |
2005年 | 208篇 |
2004年 | 187篇 |
2003年 | 195篇 |
2002年 | 147篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 37篇 |
1998年 | 27篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 20篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1974年 | 6篇 |
1971年 | 6篇 |
1925年 | 6篇 |
1924年 | 6篇 |
排序方式: 共有4235条查询结果,搜索用时 15 毫秒
971.
Coudry V Jean D Desbois C Tnibar A Laugier C George C 《The Canadian veterinary journal. La revue veterinaire canadienne》2007,48(6):623-626
Ventricular dysrhythmias are more commonly associated with myocardial disease than are supraventricular dysrhythmias. Management of arrhythmias under general anesthesia is difficult because of the dysrhythmogenic effects of the anesthetic drugs. This report describes a severe ventricular dysrhythmia observed in a pony under general anesthesia, with a severe and old myocardial fibrosis found on postmortem examination. 相似文献
972.
Catherine E. Doyle-Capitman Daniel J. Decker Cynthia A. Jacobson 《Human Dimensions of Wildlife》2018,23(4):375-390
The conservation community is increasingly taking a landscape-level approach to wildlife conservation. This approach faces obstacles, including how to ensure transboundary wildlife conservation goals that can be realized through local management actions, and how and when to engage local stakeholders in landscape conservation planning processes. Currently, local stakeholder participation is not institutionalized within these processes. This paper examines the potential role of local stakeholders in landscape conservation. In this paper, we present a preliminary model of cross-level coordination that could facilitate development and implementation of conservation across social–ecological landscapes, highlighting the possible contributions of local stakeholders. The feasibility of this model is contingent on addressing a range of challenges associated with local stakeholder participation in extra-local conservation decisions. Ultimately, we present suggestions for future research examining the potential for a locally inclusive, participatory approach to wildlife conservation across complex landscapes. 相似文献
973.
Churria CD Spinsanti E Origlia J Marcantoni H Piscopo M Loyola MH Petruccelli M 《Journal of zoo and wildlife medicine》2011,42(1):164-165
Two adult male Crimson rosellas (Platycercus elegans) and an adult female eastern rosella (Platycercus eximius) were found dead in their cages in a private aviary in March 2009, April 2010, and February 2010, respectively, without premonitory signs. Their postmortem examination showed pectoral muscle atrophy and a distended proventriculus. The proventricular mucosal surface was covered with a gelatinous, whitish material, where a large number of nematode parasites identified as Dispharynx nasuta were present. A histologic examination revealed a hyperplastic mucosa, spirurid nematodes in the mucosal layer and inflammatory mononuclear cells in the lamina propria. This is the first report of a D. nasuta infection associated with proliferative proventriculitis and subsequent death in psittacine birds. 相似文献
974.
Livestock guard dogs (LGDs; Canis familiaris) have been widely adopted by domestic sheep (Ovis aries) producers because they reduce predation by wild carnivores. LGDs were originally used in the United States to reduce coyote (Canis latrans) depredations, but their efficacy against a suite of large carnivores, including wolves (Canis lupus), brown bears (Ursus arctos), black bears (Ursus americanus), and cougars (Puma concolor), and whether specific breeds perform better than others remains unclear. To assess breed-specific effectiveness at reducing depredations from a suite of livestock predators, we compared survival rates of sheep protected by different breeds of LGDs, including three breeds from Europe (Turkish kangal, Bulgarian karakachan, and Portuguese cão de gado transmontano) and mixed-breed LGDs, “whitedog,” common in the United States. With the help of participating sheep producers, we collected cause-specific mortality data from domestic sheep in Idaho, Montana, Oregon, and Wyoming between 2013 and 2016. All three of the novel breeds of LGD tested were associated with overall reductions in sheep depredation relative to whitedogs, ranging from 61% to 95% (P < 0.05). In terms of predator-specific effectiveness, the Turkish kangal was associated with decreases in depredation from cougars (eβ = 0.31, 95% CI = 0.10–0.94, P = 0.04), black bears (eβ = 0.33, 95% CI = 0.28–0.37, P < 0.01), and coyotes (eβ = 0.56, 95% CI = 0.35–0.90, P = 0.02). The Bulgarian karakachan was associated with a decrease in coyote depredations (eβ = 0.07, 95% CI = 0.01–0.49, P < 0.01). The Portuguese transmontano was not associated with significant reductions in depredation hazard for any specific predator. Although variations in breed-specific effectiveness were subtle and nuanced, these findings will help livestock producers and wildlife managers make tailored decisions about how best to incorporate different breeds of LGD into sheep grazing regimes. 相似文献
975.
976.
Agustí Noya Beatriz Serrano‐Prez Daniel Villalba Isabel Casasús Ester Molina Irene Lpez‐Helguera Albina Sanz 《Animal Science Journal》2019,90(7):857-869
This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient‐restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica‐SUBNUT than in Pirenaica‐CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short‐term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long‐term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF‐1 and higher levels of cortisol. 相似文献
977.
Cribb NC Kenney DG Reid-Burke R 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(1):83-85
An 82-cm fragment of nasogastric tube was removed from the stomach of an adult horse under standing sedation by use of an endoscope and electrocautery snare. This is the first report of successful non-surgical removal of a nasogastric tube fragment from the stomach of a horse. 相似文献
978.
Julia Pinedo-Gil Ana Tomás-Vidal Daniel Rico Brijesh Tiwari Carlos Álvarez García Miguel Jover-Cerdá 《Journal Of Aquatic Food Product Technology》2019,28(5):495-504
Barley concentrations ranging from 0% to 32% were incorporated into rainbow trout (Oncorhynchus mykiss) diets. The effect of barley concentration on lipid peroxidation and antioxidant activity of fish fillets were analyzed. Results showed that the inclusion of barley in rainbow trout diets had an inhibitory effect on lipid oxidation, probably associated with certain bioactive compounds in barley that could interact with scavenging and reducing metabolites involved in lipid oxidation. Concentrations up to 8% of barley produced fish fillets with high antioxidant activity and higher levels of alpha-tocopherol. 相似文献
979.
980.