全文获取类型
收费全文 | 937篇 |
免费 | 93篇 |
专业分类
林业 | 61篇 |
农学 | 36篇 |
基础科学 | 2篇 |
158篇 | |
综合类 | 85篇 |
农作物 | 43篇 |
水产渔业 | 76篇 |
畜牧兽医 | 489篇 |
园艺 | 16篇 |
植物保护 | 64篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 11篇 |
2021年 | 31篇 |
2020年 | 37篇 |
2019年 | 52篇 |
2018年 | 33篇 |
2017年 | 27篇 |
2016年 | 40篇 |
2015年 | 37篇 |
2014年 | 36篇 |
2013年 | 42篇 |
2012年 | 72篇 |
2011年 | 76篇 |
2010年 | 38篇 |
2009年 | 33篇 |
2008年 | 48篇 |
2007年 | 75篇 |
2006年 | 46篇 |
2005年 | 53篇 |
2004年 | 46篇 |
2003年 | 42篇 |
2002年 | 49篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1941年 | 1篇 |
1937年 | 1篇 |
1936年 | 1篇 |
1933年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有1030条查询结果,搜索用时 15 毫秒
931.
Hugues Patural Marie St-Hilaire Alain Beuchée Nathalie Samson Jean-Paul Praud 《Research in veterinary science》2010,89(2):242-249
Background
Early postnatal abnormalities of autonomic nervous system (ANS) activity, including at baseline and following cardiorespiratory challenge, are involved in apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome. Literature data suggest that baseline ANS activity does not mature normally after premature birth.Objectives
This study performed in preterm lambs was aimed at assessing ANS maturation at baseline and following laryngeal chemoreflexes (LCR), a group of reflexes triggered by the contact of liquids with the laryngeal mucosa.Methods
Heart rate variability (HRV) and baroreflex sensitivity (BRs) were measured at baseline and after LCR during polysomnographic recordings performed in five non-sedated lambs born 15 days prematurely. Laryngeal chemoreflexes were induced by distilled water or acid (pH 2) during sleep and wakefulness on postnatal days 7 (D7) and 14 (D14, full-term equivalence).Results
While the life-threatening cardiorespiratory events of the LCR observed at D7 were no longer present at D14, baseline and post-LCR HRV and BRs indices were significantly lower at D14 compared to D7 (up to p < 0.001). These results suggest that an initial autonomic overactivity was present at D7 and normalized at D14.Conclusion
The autonomic cardiac and baroreflex control appears to follow a specific evolution in the preterm compared to the full-term newborn lamb, with an important initial autonomic stress, which normalizes at an age equivalent to full-term. Potential relevance of these findings in relation to anomalies of cardiac control in the early postnatal period, such as apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome, awaits further studies. 相似文献932.
Marie GB Hansen Mette Christoffersen Line R Thuesen Morten R Petersen Anders M Bojesen 《Acta veterinaria Scandinavica》2010,52(1):3
Background
Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.Methods
A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP®4DX ® ELISA test.Results
Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.Conclusions
Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms. 相似文献933.
Acar M Pando BF Arnold FH Elowitz MB van Oudenaarden A 《Science (New York, N.Y.)》2010,329(5999):1656-1660
Coping with variations in network dosage is crucial for maintaining optimal function in gene networks. We explored how network structure facilitates network-level dosage compensation. By using the yeast galactose network as a model, we combinatorially deleted one of the two copies of its four regulatory genes and found that network activity was robust to the change in network dosage. A mathematical analysis revealed that a two-component genetic circuit with elements of opposite regulatory activity (activator and inhibitor) constitutes a minimal requirement for network-dosage invariance. Specific interaction topologies and a one-to-one interaction stoichiometry between the activating and inhibiting agents were additional essential elements facilitating dosage invariance. This mechanism of network-dosage invariance could represent a general design for gene network structure in cells. 相似文献
934.
Audrey Sombardier Marie‐Cécile Dufour Dominique Blancard Marie‐France Corio‐Costet 《Pest management science》2010,66(1):35-43
BACKGROUND: Management of strawberry powdery mildew, Podopshaera aphanis (Wallr.), requires numerous fungicide treatments. Limiting epidemics is heavily dependent on sterol demethylation inhibitors (DMIs) such as myclobutanil or penconazole. Recently, a noticeable reduction in the efficacy of these triazole fungicides was reported by strawberry growers in France. The goal of this study was to investigate the state of DMI sensitivity of French P. aphanis and provide tools for improved pest management. RESULTS: Using leaf disc sporulation assays, sensitivity to myclobutanil and penconazole of 23 isolates of P. aphanis was monitored. Myclobutanil EC50 ranged from less than 0.1 to 14.67 mg L?1 and for penconazole from 0.04 to 4.2 mg L?1. A cross‐analysis and a Venn diagram showed that there was reduced sensitivity and a positive correlation between the less sensitive myclobutanil and penconazole isolates; 73.9% of isolates were less sensitive to a DMI and 47.8% exhibited less sensitivity to both fungicides. CONCLUSION: The results show that sensitivity to myclobutanil and, to a lesser extent, penconazole has become less efficient in strawberry powdery mildew in France. Therefore, urgent action is required in order to document its appearance and optimise methods of control. Copyright © 2009 Society of Chemical Industry 相似文献
935.
Pascal Braekman Dieter Foque Winy Messens Marie‐Christine Van Labeke Jan G Pieters David Nuyttens 《Pest management science》2010,66(2):203-212
BACKGROUND: Increasingly, Flemish greenhouse growers are using spray booms instead of spray guns to apply plant protection products. Although the advantages of spray booms are well known, growers still have many questions concerning nozzle choice and settings. Spray deposition using a vertical spray boom in tomatoes and strawberries was compared with reference spray equipment. Five different settings of nozzle type, size and pressure were tested with the spray boom. RESULTS: In general, the standard vertical spray boom performed better than the reference spray equipment in strawberries (spray gun) and in tomatoes (air‐assisted sprayer). Nozzle type and settings significantly affected spray deposition and crop penetration. Highest overall deposits in strawberries were achieved using air‐inclusion or extended‐range nozzles. In tomatoes, the extended‐range nozzles and the twin air‐inclusion nozzles performed best. Using smaller‐size extended‐range nozzles above the recommended pressure range resulted in lower deposits, especially inside the crop canopy. CONCLUSIONS: The use of a vertical spray boom is a promising technique for applying plant protection products in a safe and efficient way in tomatoes and strawberries, and nozzle choice and setting should be carefully considered. Copyright © 2009 Society of Chemical Industry 相似文献
936.
937.
938.
Sebastian M Gantz MG Tobin T Harkins JD Bosken JM Hughes C Harrison LR Bernard WV Richter DL Fitzgerald TD 《Veterinary therapeutics : research in applied veterinary medicine》2003,4(4):324-339
During 2001, central Kentucky experienced acute transient epidemics of early and late fetal losses, pericarditis, and unilateral endophthalmitis, collectively referred to as mare reproductive loss syndrome (MRLS). A toxicokinetic/statistical analysis of experimental and field MRLS data was conducted using accelerated failure time (AFT) analysis of abortions following administration of Eastern tent caterpillars (ETCs; 100 or 50 g/day or 100 g of irradiated caterpillars/day) to late-term pregnant mares. In addition, 2001 late-term fetal loss field data were used in the analysis. Experimental data were fitted by AFT analysis at a high (P <.0001) significance. Times to first abortion ("lag time") and abortion rates were dose dependent. Lag times decreased and abortion rates increased exponentially with dose. Calculated dose x response data curves allow interpretation of abortion data in terms of "intubated ETC equivalents." Analysis suggested that field exposure to ETCs in 2001 in central Kentucky commenced on approximately April 27, was initially equivalent to approximately 5 g of intubated ETCs/day, and increased to approximately 30 g/day at the outbreak peak. This analysis accounts for many aspects of the epidemiology, clinical presentations, and manifestations of MRLS. It allows quantitative interpretation of experimental and field MRLS data and has implications for the basic mechanisms underlying MRLS. The results support suggestions that MRLS is caused by exposure to or ingestion of ETCs. The results also show that high levels of ETC exposure produce intense, focused outbreaks of MRLS, closely linked in time and place to dispersing ETCs, as occurred in central Kentucky in 2001. With less intense exposure, lag time is longer and abortions tend to spread out over time and may occur out of phase with ETC exposure, obscuring both diagnosis of this syndrome and the role of the caterpillars. 相似文献
939.
Hugh Cai Marie Archambault John F Prescott 《Journal of veterinary diagnostic investigation》2003,15(5):465-469
This study evaluated 16S rRNA gene sequence analysis methods as tools for identification of 22 phenotypically difficult to identify veterinary clinical bacterial isolates in a veterinary diagnostic laboratory. The study compared 16S rRNA gene sequencing and conventional phenotypic identification methods. Using 16S rRNA full-gene sequencing, 95% (21/22) of the isolates were identified to the genus level and 86% (19/22) to the species level. The conventional or commercially available manual identification phenotypic characterization methods presumptively identified 91% (20/22) of the isolates to the genus level and 1 isolate to the species level. However, only 55% (12/22) or 4.5% (1/22) of the phenotypic identifications were correct at the genus or species level when they were compared with the 16S rRNA full-gene sequencing. This study also compared 16S rRNA full-gene and partial-gene sequencing. The results demonstrated that the best 16S rRNA gene-sequencing approach is full-gene sequencing because it gives the most precise species identification. Sequencing of the variable regions 1, 2, and 3 of the 16S rRNA gene could be used for tentative identification because the ability of this sequencing to identify bacteria to the genus level is similar to that of the 16S rRNA full-gene sequencing. This method identified only 14% (3/22) isolates differently to the species level compared with the 16S rRNA full gene sequence. Sequencing of the variable regions 7, 8, and 9 is not recommended because it gives more ambiguous identifications. The cost of a 16S RNA full-gene-sequencing analysis was Can 160 dollars and Can 60 dollars for a partial 16S rRNA gene sequence, i.e., sequencing of variable regions 1, 2, and 3 or variable regions 7, 8 and 9. 相似文献
940.