全文获取类型
收费全文 | 151篇 |
免费 | 12篇 |
专业分类
林业 | 8篇 |
农学 | 11篇 |
基础科学 | 1篇 |
32篇 | |
综合类 | 11篇 |
农作物 | 4篇 |
水产渔业 | 17篇 |
畜牧兽医 | 53篇 |
园艺 | 4篇 |
植物保护 | 22篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 1篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 9篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 1篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 0 毫秒
1.
Mouillot Florent Ratte Jean-Pierre Joffre Richard Moreno Jose Manuel Rambal Serge 《Landscape Ecology》2003,18(7):665-674
Based on recent needs to accurately understand fire regimes and post-fire vegetation resilience at a supra-level for carbon cycle studies, this article focusses on the coupled history of fire and vegetation pattern for 40 years on a fire-prone area in central Corsica (France). This area has been submitted since the beginning of the 20th century to land abandonment and the remaining land management has been largely controlled by frequent fires. Our objectives were to rebuild vegetation and fire maps in order to determine the factors which have driven the spatial and temporal distribution of fires on the area, what were the feed backs on the vegetation dynamics, and the long-term consequences of this inter-relationship. The results show a stable but high frequency of small fires, coupled with forest expansion over the study period. The results particularly illustrate the spatial distribution of fires according to topography and vegetation, leading to a strong contrast between areas never burnt and areas which have been burnt up to 7 times. Fires, when occuring, affect on average 9 to 12% of the S, SE and SW facing slopes (compared to only 2 to 5% for the N facing slopes), spread recurrently over ridge tops, affect all the vegetation types but reburn preferentially shrublands and grasslands. As these fire-proning parameters have also been shown to decrease the regeneration capacity of forests, this study highlights the needs in spatial studies (both in terms of fire spread and vegetation dynamic) to accurately apprehend vegetation dynamic and functionning in fire-prone areas.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
2.
Joo Carlos de Moraes S Lucien Sguy Florent Tivet Rattan Lal Serge Bouzinac Paulo Rogrio Borszowskei Clever Briedis Josiane Burkner dos Santos Daiani da Cruz Hartman Clayton Giani Bertoloni Jadir Rosa Theodor Friedrich 《Land Degradation \u0026amp; Development》2015,26(6):531-543
The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass‐C input and its biodiversity under no‐till (NT) drives soil restoration of degraded agro‐ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow‐based conventional tillage (CT) on soil organic carbon (SOC) stock vis‐à‐vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0·58 and 0·67 Mg C ha−1 y−1 in the 0‐ to 20‐cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0·59 for the PG site and ranged from 0·48 to 1·30 Mg C ha−1 y−1 for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14·2% at the PG site and ~20·5% at the LRV site. The SOC resilience index ranged from 0·29 to 0·79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
Rezzi S Giani I Héberger K Axelson DE Moretti VM Reniero F Guillou C 《Journal of agricultural and food chemistry》2007,55(24):9963-9968
The combination of (1)H NMR fingerprinting of lipids from gilthead sea bream (Sparus aurata) with nonsupervised and supervised multivariate analysis was applied to differentiate wild and farmed fish and to classify farmed specimen according to their areas of production belonging to the Mediterranean basin. Principal component analysis (PCA) applied on processed (1)H NMR profiles made a clear distinction between wild and farmed samples. Linear discriminant analysis (LDA) allowed classification of samples according to the geographic origin, as well as for the wild and farmed status using both PCA scores and NMR data as variables. Variable selection for LDA was achieved with forward selection (stepwise) with a predefined 5% error level. The methods allowed the classification of 100% of the samples according to their wild and farmed status and 85-97% to geographic origin. Probabilistic neural network (PNN) analyses provided complementary means for the successful discrimination among classes investigated. 相似文献
4.
van Oost BA Versteeg SA Slappendel RJ 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2004,18(3):282-288
Von Willebrand disease type III is widespread in Dutch Kooiker dogs. To eradicate von Willebrand disease from the breed, affected dogs and nonsymptomatic carriers must be excluded from breeding. Previous efforts to detect carriers in Kooiker dogs by a von Willebrand factor antigen assay were not satisfactory because of considerable overlap of plasma concentrations in normal dogs and carriers. The aim of this study was to develop and apply a DNA test for the detection of von Willebrand disease carriers in the Kooiker breed. Two mutations in the von Willebrand factor gene in affected Kooiker dogs have been described previously, a splice site mutation at the border of intron 16 and exon 16 and a missense mutation in exon 3. We have developed polymerase chain reaction tests for both mutations in genomic DNA. The missense mutation most likely is a neutral variant and appears to be a polymorphism present in many breeds. The allele-specific oligonucleotide test for the splice site mutation was applied in the selection of animals cleared to breed by the Dutch breeding club. In a few years, the mutation has been eliminated from the breeding stock without apparent increase of inbreeding or preferential sire usage. 相似文献
5.
Yeen Ten Hwang Marie-Line Gentes Dennilyn L Parker Serge Larivière Fran?ois Messier 《Journal of zoo and wildlife medicine》2004,35(4):515-519
A total of 20 (14 females, six males) captive striped skunks (Mephitis mephitis) with miniature temperature dataloggers implanted free in the abdominal cavity were examined for reproductive performance and pathology because of implants. Eleven of 12 female skunks reproduced successfully 45.9+/-3.7 days after surgery to remove implanted dataloggers. The pregnancy rate of 91.7% (11/12) was much higher than other captive studies and was comparable with that of wild skunks. Eight striped skunks (six males, two females) that were euthanatized and necropsied after having implants in the abdominal cavity for 5 mo showed no apparent pathology associated with the implant. Implantation of the intraperitoneal devices did not lead to complications in abdominal tissues. Neither implant nor surgery affected reproduction. We conclude that implanted dataloggers can safely be used in physiologic studies of striped skunks or possibly other small carnivores in captive or field studies. 相似文献
6.
Reproductive phenology was observed over three years in a Eucalyptus grandis seed orchard in Madagascar to determine the impact of geographic differences of parental selections on the expected genetic composition of seed crops. Pollen flow (observed pollen cloud) was deduced from a paternity assignment based on sampling from one year’s seed production. The two approaches were used to verify whether knowledge of phenology is sufficient to predict the genetic quality of the seeds collected. Despite the high flowering level, with a constant cycle over three years, the results demonstrated wide reproductive phenological differences associated with the parents’ origin, suggesting putative pollination disequilibrium. From both observed and expected pollen clouds, the results showed preferential mating among different provenances, which has consequences for seed crop composition. Phenological observations, which can be made inexpensively, can be used to promote methods of effective seed orchard management in order to improve the genetic quality of seeds. 相似文献
7.
8.
Eliane Gonzalez-Rodriguez Serge Y. Maestrini 《Aquaculture (Amsterdam, Netherlands)》1984,36(3):245-256
Three Brazilian and 9 French agricultural fertilizers were compared with Conway mixture, as nutrient enrichment for supporting the growth of 16 marine algae. Fertilizers containing only nitrogen and phosphorus appeared to be suitable. However, a few algae grew better in all-nutrient-enriched Conway medium. Addition of chelators did not generate better growth. Matrix-free fertilizers were found more convenient in use. A table is given to show the cheapest and/or best nutrient enrichment for each algal strain tested. 相似文献
9.
10.
Bonnefont-Rebeix C Marchal T Bernaud J Pin JJ Leroux C Lebecque S Chabanne L Rigal D 《Veterinary immunology and immunopathology》2007,118(1-2):134-139
Toll-like receptors (TLRs) are a family of functionally important receptors for recognition of pathogen-associated molecular pattern (PAMP) since they trigger the pro-inflammatory response and upregulation of costimulatory molecules, linking the rapid innate response to adaptative immunity. In human leukocytes, TLR3 has been found to be specifically expressed in dendritic cells (DC). This study examined the expression of TLR3 in canine monocytes-derived DC (cMo-DC) and PBMC using three new anti-TLR3 mAbs (619F7, 722E2 and 713E4 clones). The non-adherent cMo-DC generated after culture in canine IL-4 plus canine GM-CSF were labelled with the three anti-TLR3 clones by flow cytometry, with a strong expression shown for 619F7 and 722E2 clones. By contrast, TLR3 expression was low to moderate in canine monocytes and lymphocytes. These results were confirmed by Western blot using 619F7 and 722E2 clones and several polypeptide bands were observed, suggesting a possible cleavage of TLR3 molecule or different glycosylation states. In addition, TLR3 was detectable in immunocytochemistry by using 722E2 clone. In conclusion, this first approach to study canine TLR3 protein expression shows that three anti-TLR3 clones detect canine TLR3 and can be used to better characterize canine DC and the immune system of dogs. 相似文献