全文获取类型
收费全文 | 230篇 |
免费 | 26篇 |
专业分类
林业 | 9篇 |
农学 | 8篇 |
61篇 | |
综合类 | 10篇 |
农作物 | 24篇 |
水产渔业 | 10篇 |
畜牧兽医 | 110篇 |
园艺 | 4篇 |
植物保护 | 20篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 18篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 25篇 |
2013年 | 20篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
排序方式: 共有256条查询结果,搜索用时 343 毫秒
131.
132.
133.
Gerardo Rubio Valeria Faggioli Javier D. Scheiner Flavio H. Gutiérrez‐Boem 《植物养料与土壤学杂志》2012,175(6):810-871
It has been reported for many soils that maize (Zea mays L.) has a higher soil‐P critical level than soybean (Glycine max L.) and sunflower (Helianthus annuus L). The objective of this work was to compare the rhizosphere P depletion in these three species in order to investigate if they differ in their capacity to acquire soil P. Sequential P fractionation and pH were determined in rhizosphere and nonrhizosphere soil samples from field and greenhouse experiments. Neither sunflower (the species with highest rhizosphere acidification) nor soybean or maize showed a significant relationship between P depletion and rhizosphere pH. The labile P fraction and the NaOH‐Pi fraction had lower values in the rhizosphere than in the bulk soil in 38% and 77% of the studied cases, respectively. Sunflower and especially maize presented a more intense Pi depletion than soybean. The comparison between sunflower and maize revealed that neither of them took a clear advantage over the other in terms of P depletion. Rhizosphere Pi depletion was associated with the amount of P acquired by the plants. We conclude that the accessibility to different P pools does not explain the differences in soil‐P critical levels among the three species. 相似文献
134.
Alonso Pardo-Vargas Ingrid de Barcelos Oliveira Paulo Roberto Soares Stephens Claudio Cesar Cirne-Santos Izabel Christina Nunes de Palmer Paix?o Freddy Alejandro Ramos Carlos Jiménez Jaime Rodríguez Jackson Antonio Lamounier Camargos Resende Valeria Laneuville Teixeira Leonardo Castellanos 《Marine drugs》2014,12(7):4247-4259
135.
de Andrade Moura L Ortiz-Ramirez F Cavalcanti DN Ribeiro SM Muricy G Teixeira VL Fuly AL 《Marine drugs》2011,9(8):1346-1358
The ischemic disorders, in which platelet aggregation and blood coagulation are involved, represent a major cause of disability and death worldwide. The antithrombotic therapy has unsatisfactory performance and may produce side effects. So, there is a need to seek molecules with antithrombotic properties. Marine organisms produce substances with different well defined ecological functions. Moreover, some of these molecules also exhibit pharmacological properties such as antiviral, anticancer, antiophidic and anticoagulant properties. The aim of this study was to evaluate, through in vitro tests, the effect of two extracts of brown algae and ten marine sponges from Brazil on platelet aggregation and blood coagulation. Our results revealed that most of the extracts were capable of inhibiting platelet aggregation and clotting measured by plasma recalcification tests, prothrombin time, activated partial thromboplastin time, and fibrinogenolytic activity. On the other hand, five of ten species of sponges induced platelet aggregation. Thus, the marine organisms studied here may have molecules with antithrombotic properties, presenting biotechnological potential to antithrombotic therapy. Further chemical investigation should be conducted on the active species to discover useful molecules for the development of new drugs to treat clotting disorders. 相似文献
136.
DNA-based methods for identification and quantification of small grain cereal mixtures and fingerprinting of varieties 总被引:1,自引:0,他引:1
Valeria Terzi Caterina Morcia Antonio Gorrini A. Michele Stanca Peter R. Shewry Primetta Faccioli 《Journal of Cereal Science》2005,41(3):213-220
The composition of cereal-based foods is a key factor in determining the quality and safety of the final product while the reliable identification of cereal species and cultivars are essential for the handling, marketing and processing of grain and for the protection of plant breeders' rights. Analytical methods have therefore been developed and applied to identify and quantify cereal species in food products and also to fingerprint and identify grain at the genotype and variety levels. DNA-based methods for the detection and quantification of mixtures of small grain cereals are reviewed, together with the recent development of molecular markers for varietal fingerprinting. 相似文献
137.
138.
Valeria F. Del Coco María A. Córdoba Gladys Bilbao Aldana Pinto de Almeida Castro Juan A. Basualdo Ronald Fayer Mónica Santín 《Research in veterinary science》2014
Cryptosporidium parvum from 73 dairy calves less than two months old from Buenos Aires province (Argentina) were molecularly characterized using sequence analysis of the GP60 gene. Seventy-five sequences were obtained, and seven different subtypes were identified, all belonging to the IIa subtype family. The most common subtypes were IIaA20G1R1 (27/75), IIaA22G1R1 (16/75), and IIaA18G1R1 (13/75). Subtypes IIaA21G1R1, IIaA23G1R1, IIaA16G1R1 and IIaA19G1R1 were found sporadically. Two samples contained mixed infections with IIaA21G1R1 and IIaA22G1R1. A significant association was found between subtypes and geographic location, whereas there was no relation between subtypes and presence of diarrhea. Three of the subtypes found in this study (IIaA16G1R1, IIaA18G1R1, and IIaA19G1R1) were previously identified in humans. These findings suggest that cattle could play an important role in the transmission of cryptosporidiosis to humans in Buenos Aires province. 相似文献
139.
Gergely V Montes-Bayón M Fodor P Sanz-Medel A 《Journal of agricultural and food chemistry》2006,54(13):4524-4530
The complementary use of two different liquid chromatographic mechanisms coupled to inductively coupled plasma mass spectrometry (ICP-MS) for selenium (Se) specific detection has permitted the screening of the most abundant Se-containing fractions in selenized alfalfa sprouts (Medicago sativa). Aqueous extracts of the sprouts were fractionated first by size exclusion chromatography (SEC) using a Superdex Peptide column and a mobile phase containing an ammonium acetate buffer (pH 7). Further purification of the individual SEC Se-containing fractions was carried out using two different chromatographic systems: a Shodex Ashaipack column, with a mixed mechanism of size exclusion and ion exchange, and a conventional reversed phase C8 using ion-pairing reagents. In both cases, the columns were coupled to an inductively coupled plasma mass spectrometer equipped with an octapole reaction system for Se specific detection. This system allowed the on-line monitoring of the most abundant Se isotopes (78Se, 80Se) by reducing the possible polytomic interferences affecting these ions by adding hydrogen (2 mL min(-1)) to the octapole reaction cell. The results obtained by both separation mechanisms were highly comparable, revealing the presence of Se-methionine and Se-methyl selenocysteine. Both compounds were then confirmed by analyzing the corresponding fractions by electrospray quadrupole-time-of-flight (ESI-Q-TOF) mass spectrometry. Finally, an additional Se-containing species showing Se isotope distribution was detected at a molecular ion m/z 239 in the ESI-Q-TOF. The collision-induced dissociation of the m/z 239 and 237 ions (corresponding to 80Se and 78Se isotopes, respectively) revealed the possible presence as well of a derivative of the Se-2-propenyl selenocysteine. 相似文献
140.
Rodolfo A. Golluscio Valeria Sigal Escalada Juliana Pérez 《Strength and Conditioning Journal》2009,62(2):171-178
In arid ecosystems, a few large summer rains frequently differentiate wet years from dry ones. However, use of this additional water by plants has limited experimental evidence. We applied a 16-mm summer water pulse (12% of mean annual precipitation) to two plant communities of the Patagonian steppe, and compared responses of three dominant species, which can be ordered by decreasing xerophytism and increasing rooting depth and summer activity: 1) colapiche, evergreen dwarf shrub (Nassauvia glomerulosa [Lag.] Don); 2) coirón amargo, evergreen grass (Stipa speciosa Trin. et Rupr.); and 3) neneo, drought deciduous shrub (Mulinum spinosum [Cav.] Pers.). Shallow-rooted species (S. speciosa and N. glomerulosa), which use water from dry soil layers, showed a greater leaf water potential response to watering than deep-rooted species (M. spinosum). Leaf water potential response was greater and quicker in xerophytic species than in mesophytic ones (N. glomerulosa > S. speciosa > M. spinosum). However, this response only translated into leaf conductance and transpiration responses for coirón amargo, probably because the species with winter phenological cycle (N. glomerulosa) is less able to utilize summer water inputs than species with a summer phenological cycle (S. speciosa). The lack of response of deep-rooted M. spinosum in leaf conductance, transpiration, and photosynthesis may have been due to the high leaf water potential of control plants. Instead, in S. speciosa and N. glomerulosa net photosynthesis decreased below zero following watering, suggesting the start of growth pulses. The complex chain of plant processes triggered by rainfall, and the constraints imposed to different species by rooting depth, phenology, and xerophytism, could explain the frequent low response to both large rainfall events and above-average rainfall years in this arid community. Our results suggest that, paradoxically, water may be suboptimally used at local scales in arid rangeland ecosystems. 相似文献