全文获取类型
收费全文 | 451篇 |
免费 | 38篇 |
专业分类
林业 | 26篇 |
农学 | 9篇 |
基础科学 | 3篇 |
70篇 | |
综合类 | 37篇 |
农作物 | 18篇 |
水产渔业 | 39篇 |
畜牧兽医 | 255篇 |
园艺 | 8篇 |
植物保护 | 24篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 16篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 26篇 |
2012年 | 32篇 |
2011年 | 32篇 |
2010年 | 20篇 |
2009年 | 14篇 |
2008年 | 26篇 |
2007年 | 31篇 |
2006年 | 20篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1966年 | 1篇 |
排序方式: 共有489条查询结果,搜索用时 15 毫秒
91.
Berlanda M Zotti A Brandazza G Poser H Calò P Bernardini M 《The Canadian veterinary journal. La revue veterinaire canadienne》2011,52(12):1334-1338
Magnetic resonance and computed tomography features of 4 cases of canine congenital vertebral anomalies (CVAs) are discussed. Two of the cases represent unusual presentations for such anomalies that commonly affect screw-tail or toy breeds. Moreover, the combination of CVAs and a congenital peritoneo-pericardial diaphragmatic hernia has never before been imaged. 相似文献
92.
Francesco Carimi Francesco Mercati Roberto De Michele Maria Carola Fiore Paolo Riccardi Francesco Sunseri 《Genetic Resources and Crop Evolution》2011,58(7):967-975
The Sicilian grape cultivar ‘Nero d’Avola’ is among the oldest and most cultivated in the island, taking part in the production
of several red wines exported worldwide, including DOC wines (Etna Rosso and Cerasuolo di Vittoria). Due to the ancient origin
and repeated clonally propagation of the cultivar, phenotypic variability has been observed. Clone identification in this
important cultivar has so far relied on phenotypic and chemical traits analyses, often affected by environmental conditions.
Genetic markers, such as microsatellites, are particularly useful for cultivar identification, parentage testing, pedigree
reconstruction and population structure studies. In the present paper, microsatellites were used to analyze the intra-varietal
genetic diversity among 118 plants of ‘Nero d’Avola’, collected in 30 vineyards displaced in different areas of Sicily. Out
of 22 microsatellites, 11 showed polymorphism among samples and 15 different phylogenetic groups were identified. Results
show that ‘Nero d’Avola’ actually comprises different genetic profiles, although most of clones share a common origin. 相似文献
93.
Jason Grainger Kerr Michele Burford Jon Olley James Udy 《Water, air, and soil pollution》2011,217(1-4):523-534
This study investigated the storage of nitrogen (N) and phosphorus (P) in the biomass, bed sediments and water column of representative reaches of a sub-tropical river, the upper Brisbane River (UBR), Queensland, Australia, and contrasted instream storage with total wet season exports. In reaches which contained accumulated fine sediments, more than 87% of total P and between 50% and 92% of total N were stored in the surface sediments. The lower proportion of N in sediment at some sites was attributed to substantial differences in the N/P ratios of sediments and macrophytes. At one site, the riverbed was dominated by cobbles and boulders and total nutrient stocks were comparatively low and dominated by the biomass. In reaches with a narrow channel and intact riparian cover, biomass N and P were stored predominately in leaf litter, while in wider unshaded reaches, macrophytes dominated. Total instream storage in the mid to lower reaches of the UBR was ??50.9 T for N and ??18.1 T for P. This was considerably higher than total wet season N (??15.6 T) and P (??2.7 T) exports from the UBR. The first flow event in the river after a prolonged period of no flow resulted in the export of free-floating, emergent species Azolla. The estimated biomass of Azolla in the mid to lower reaches of the river was equivalent to approximately 24% and 9% of the total N and P flux, indicating that this may be a significant, previously unaccounted for, source at peak flow. 相似文献
94.
95.
Michele R. S. Simões Joal J. B. Leal Alessandro P. Minho Cláudia C. Gomes Michael D. MacNeil Rodrigo F. Costa Vinícius S. Junqueira Patrícia I. Schmidt Fernando F. Cardoso Arione A. Boligon Marcos J. Yokoo 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(2):177-188
Our goal was to define a breeding objective for Brangus beef cattle in Brazil. Bioeconomic models were produced and used to estimate economic values (EVs). The scenarios simulated were typical full-cycle beef production systems that are used in tropical and subtropical regions. The breeding objective contained pregnancy rate (PR), warm carcass weight (WCW), mature cow weight (MCW), number of nematode eggs per gram of faeces (EPG) and tick count (TICK). Two models were used in series to estimate the EV. A deterministic model was used to simulate effects of PR, WCW and MCW on profitability with a constant parasite load. Subsequently, stochastic models were used to estimate economic values for TICK and EPG as consequences of their environmental effects on weight gains, mortality and health costs. The EV of PR, WCW, MCW, EPG and TICK, was US$1.59, US$2.11, −US$0.24, −US$5.35 and −US$20.88, respectively. Results indicate positive emphasis should be placed on PR (12.49%) and WCW (65.07%) with negative emphasis on MCW (13.92%), EPG (2.77%) and TICK (5.75%). In comparison with the indexes usually used, these results suggest a reformulation in the selection indexes of the beef production system in tropical and subtropical regions in order to obtain greater profitability. 相似文献
96.
97.
Carol Reinero Lance C. Visser Heidi B. Kellihan Isabelle Masseau Elizabeth Rozanski Cécile Clercx Kurt Williams Jonathan Abbott Michele Borgarelli Brian A. Scansen 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2020,34(2):549-573
Pulmonary hypertension (PH), defined by increased pressure within the pulmonary vasculature, is a hemodynamic and pathophysiologic state present in a wide variety of cardiovascular, respiratory, and systemic diseases. The purpose of this consensus statement is to provide a multidisciplinary approach to guidelines for the diagnosis, classification, treatment, and monitoring of PH in dogs. Comprehensive evaluation including consideration of signalment, clinical signs, echocardiographic parameters, and results of other diagnostic tests supports the diagnosis of PH and allows identification of associated underlying conditions. Dogs with PH can be classified into the following 6 groups: group 1, pulmonary arterial hypertension; group 2, left heart disease; group 3, respiratory disease/hypoxia; group 4, pulmonary emboli/pulmonary thrombi/pulmonary thromboemboli; group 5, parasitic disease (Dirofilaria and Angiostrongylus); and group 6, disorders that are multifactorial or with unclear mechanisms. The approach to treatment of PH focuses on strategies to decrease the risk of progression, complications, or both, recommendations to target underlying diseases or factors contributing to PH, and PH-specific treatments. Dogs with PH should be monitored for improvement, static condition, or progression, and any identified underlying disorder should be addressed and monitored simultaneously. 相似文献
98.
Hsiang-Tai Cheng Michele C. Marra James D. Leiby 《American Journal of Potato Research》1992,69(10):677-690
A new proposal for U.S. farm commodity programs would allow more flexibility in planting decisions on program acreage. This work examines the effect of such a proposal on potato production acreage. These results are used to project changes in total revenue accruing to existing potato producers and to the potato industry as a whole. The results indicate that the short term impact on the potato industry as a whole would be relatively minor but the impact could be unevenly distributed across producing regions of the U.S., causing some potential local discomfort. 相似文献
99.
Louis Cara Patrick Borel Martine Armand Michele Senft Huguette Lafont Henri Portugal Anne-Marie Pauli Daniele Boulze Christianne Lacombe Denis Lairon 《Plant foods for human nutrition (Dordrecht, Netherlands)》1991,41(2):135-150
The present study was performed to investigate the possible effects of wheat germ supplementation on lipid metabolism in humans. Ten free-living adult subjects participated in the study. None was obese or diabetic. They all presented an, hypercholesterolemia (from 6.58 to 9.50 mM), associated in 6 over 10 cases to an hypertriglyceridemia (from 1.70 to 5.00 mM). The subjects were studied in three consecutive periods, during which they first were on their usual diet (first week), they then ingested a daily supplement of 30 g wheat germ (4 weeks) and then they returned to their usual basal diet (4 weeks follow-up). Dietary records were obtained for 7 and 3 consecutive days before and during wheat germ supplementation, respectively. Fasting blood samples were taken at the end of each period. After 4 weeks of wheat, germ intake, glycemia did not change while total plasma cholesterol significantly decreased (paired Student'st test,p0.05) from 7.80 to 7.15 mM. LDL and HDL cholesterol values did not show marked changes, but VLDL cholesterol significantly dropped by 40.6%. Thus, the plasma/HDL total cholesterol ratio was significantly lower. Apoprotein B and A1 decreased. In the hypertriglyceridemic subjects, this was accompanied by a significant reduction of plasma triglycerides (1.64 vs. 2.68 mM) and a marked drop of VLDL triglycerides (–51%). Taken as a whole, the present results obtained in humans are very close to those previously obtained in the rat [40] and point out that wheat germ may play a beneficial role in the dietary management of hyperlipidemia.Part of the data communicated in this paper was presented at the Fibre 90 Conference, 17–20 April 1990, Norwich, UK. 相似文献
100.
David J. Burke Shun Zhu Michele P. Pablico-Lansigan Charlotte R. Hewins Anna Cristina S. Samia 《Biology and Fertility of Soils》2014,50(7):1169-1173
We examined the effect of TiO2 nanoparticles (NPs) on the growth of maize and soybean plants and associated soil microbial communities. Plants were grown in a greenhouse, and low levels of undoped or nitrogen-doped TiO2 NPs were applied. Plant growth and nutrient content were determined, and effects of NPs on composition of soil microbial communities were examined using terminal restriction fragment length polymorphism analysis (TRFLP) of rDNA. We found no significant effects of TiO2 NPs on plant growth, nutrient content, or the composition of bacterial communities within the rhizosphere. However, arbuscular mycorrhizal fungal communities were affected by application of undoped and nitrogen-doped TiO2 NPs. This observation may be partially attributed to the small but significant TiO2 NP uptake levels in the root tissues of both plants. Our results suggest that even low concentrations of TiO2 NPs may influence some important groups of soil microbes, such as mycorrhizal fungi, but changes in the composition of microbial communities may not affect plant growth under conditions of adequate moisture and nutrients. 相似文献