全文获取类型
收费全文 | 442篇 |
免费 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 19篇 |
2015年 | 27篇 |
2014年 | 18篇 |
2013年 | 28篇 |
2012年 | 35篇 |
2011年 | 47篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 40篇 |
2006年 | 22篇 |
2005年 | 32篇 |
2004年 | 19篇 |
2003年 | 22篇 |
2002年 | 13篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1981年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有463条查询结果,搜索用时 265 毫秒
131.
The Egyptian Vulture Neophron percnopterus population in Morocco has undergone a marked decline since the 1980s to the point of nearing local extinction in the twenty-first century. A field study of some possible sites for Egyptian Vultures was carried out over six days during June 2014 in the Middle Atlas Mountains, Morocco. We counted a total of 48 Egyptian Vultures at three different localities: two occupied breeding sites and one communal roost that hosted 40 vultures of different ages. A (probable) singe adult bird at the breeding site was located and a previously occupied site was also visited. A preliminary survey amongst local people indicated that threats faced by this species are predator poisoning in some areas, and the use of vulture parts for traditional medicine. Given that the species is considered globally Endangered and populations continue to decline in many areas, the discovered population reported here, although relatively small, is of national and regional (North-west Africa) importance. We expect this new situation will revive the hopes for studying and conserving this and other vulture species in Morocco and North-west Africa in general. 相似文献
132.
Dominique Jolly I. Colin Prentice Raymonde Bonnefille Aziz Ballouche Martin Bengo Patrice Brenac Guillaume Buchet David Burney Jean-Pierre Cazet Rachid Cheddadi Therese Edorh Hilaire Elenga Saida Elmoutaki Joel Guiot Fouzia Laarif Henry Lamb Anne-Marie Lezine Jean Maley Muaka Mbenza Odile Peyron Maurice Reille Isabelle Reynaud-Farrera Guy Riollet Jim C. Ritchie Emile Roche Louis Scott Immaculate Ssemmanda Herbert Straka Mohammed Umer Elise Van Campo Sikiminywa Vilimumbalo Annie Vincens Martyn Waller 《Journal of Biogeography》1998,25(6):1007-1027
Biome reconstruction from pollen and plant macrofossil data provides an objective method to reconstruct past vegetation. Biomes for Africa and the Arabian peninsula have been mapped for 6000 years bp and provide a new standard for the evaluation of simulated palaeovegetation distributions. A test using modern pollen data shows the robustness of the biomization method, which is able to predict the major vegetation types with a high confidence level. The application of the procedure to the 6000 years data set (pollen and plant macrofossil analyses) shows systematic differences from the present that are consistent with the numerous previous regional and continental interpretations, while providing a more extensive and more objective basis for such interpretations. Madagascar, eastern, southern and central Africa show only minor changes in terms of biomes, compared to present. Major changes in biome distributions occur north of 15°N, with steppe in many low-elevation sites that are now desert, and temperate xerophytic woods/scrub and warm mixed forest in the Saharan mountains. These shifts in biome distributions imply significant changes in climate, especially precipitation, between 6000 years and present, reflecting a change in monsoon extent combined with a southward expansion of Mediterranean influence. 相似文献
133.
Wakuma Bayissa Samira A. Mohamed Godwin P. Kaaya John M. Wagacha Rachid Hanna 《Biocontrol Science and Technology》2016,26(2):274-290
Entomopathogenic fungi are among biocontrol agents being considered for the control of aphids on a variety of crops. Predatory coccinellids, although generalist, are also among important natural enemies that must be conserved for aphid management. Laboratory studies were carried out to investigate the interaction between three vegetable-infesting aphids, Metarhizium anisopliae isolate ICIPE 62 and the coccinellid predator Cheilomenes lunata. At a concentration of 1?×?108?conidial?ml–1, the fungus was found to cause mortality of 7.5% to C. lunata, compared to 2.5% mortality in the control at 10?days post-treatment. Female adult C. lunata to which fungus-infected aphids were offered as prey never accepted them as food source in non-choice bioassays. However, live and dead non-infected aphids were fed upon. In choice bioassay, a total of 1–3 out of 24 infected non-sporulating aphids per species (average of 0.1–0.4 aphids per arena) were consumed by 48?h-starved C. lunata within a period of 60?min, but avoided sporulating cadavers. Foraging adult C. lunata enhanced the spread of conidia of M. anisopliae from infected cadavers to fourth instars Aphis gossypii feeding on okra (0.8–15.0% mortality), Brevicoryne brassicae (3.3–15.0% mortality) and Lipaphis pseudobrassicae (0.8–14.2% mortality) on kale plants. Results of this study demonstrate compatibility between M. anisopliae and C. lunata, and could provide a sustainable strategy for effective management of aphids on crucifers and okra cropping systems. 相似文献
134.
Gertrude Membang Zachee Ambang Hermine Claudine Mahot Apollin Fotso Kuate Komi Kouma Mokpokpo Fiaboe Rachid Hanna 《Journal of Applied Entomology》2020,144(6):468-480
Management of the banana root borer (BRB), Cosmopolites sordidus (Germar; Coleoptera: Curculionidae), remains a challenge in banana and plantain production worldwide. Synthetic pesticides remain the most widely used solution while mycoinsecticides are increasingly being recommended. In this study, we selected indigenous isolates of Beauveria bassiana and Metarhizium anisopliae collected from plantain fields in Cameroon, and tested them in the laboratory for their viability, pathogenicity and virulence against all C. sordidus life stages. Of 13 isolates initially screened for spore germination and pathogenicity to adult weevils in conidial suspension of 3.2 × 108 conidia/ml, eight isolates with high to moderate germination and highest weevil mortality were selected for dose–response bioassays with four concentrations per isolate: 3.2 × 102, 3.2 × 104, 3.2 × 106 and 3.2 × 108 conidia/ml. The virulent isolates from adult bioassays were tested with eggs, larva and pupae in conidial suspension of 3.2 × 108 conidia/ml. Isolates performance depended on insect life stage with significantly high pathogenicity and virulence against larval, pupa and adult stages. The Beauveria isolate BIITAC6.2.2 caused the highest mortality rates followed by MIITAC1.1.5. Lethal times and lethal concentrations were relatively low for the three M. anisopliae isolates and three B. bassiana isolates which were the best isolates in almost all insect life stages. Apart from being effective in multiple life stages, these isolates were transmitted horizontally from one stage to another when eggs and pupae were treated. The implication of these findings for integrated management of the BRB, and potential biopesticides development and commercialization are discussed. 相似文献
135.
136.
Caio T. C. C. Rachid Fabiano C. Balieiro Eduardo S. Fonseca Raquel Silva Peixoto Guilherme M. Chaer James M. Tiedje Alexandre S. Rosado 《PloS one》2015,10(2)
Fungi are ubiquitous and important contributors to soil nutrient cycling, playing a vital role in C, N and P turnover, with many fungi having direct beneficial relationships with plants. However, the factors that modulate the soil fungal community are poorly understood. We studied the degree to which the composition of tree species affected the soil fungal community structure and diversity by pyrosequencing the 28S rRNA gene in soil DNA. We were also interested in whether intercropping (mixed plantation of two plant species) could be used to select fungal species. More than 50,000 high quality sequences were analyzed from three treatments: monoculture of Eucalyptus; monoculture of Acacia mangium; and a mixed plantation with both species sampled 2 and 3 years after planting. We found that the plant type had a major effect on the soil fungal community structure, with 75% of the sequences from the Eucalyptus soil belonging to Basidiomycota and 19% to Ascomycota, and the Acacia soil having a sequence distribution of 28% and 62%, respectively. The intercropping of Acacia mangium in a Eucalyptus plantation significantly increased the number of fungal genera and the diversity indices and introduced or increased the frequency of several genera that were not found in the monoculture cultivation samples. Our results suggest that management of soil fungi is possible by manipulating the composition of the plant community, and intercropped systems can be a means to achieve that. 相似文献
137.
Hicham Fatnassi Jeannine Pizzol Rachid Senoussi Antonio Biondi Nicolas Desneux Christine Poncet Thierry Boulard 《PloS one》2015,10(5)
Frankliniella occidentalis (Pergande) is a key pest of various crops worldwide. In this study, we analyse the dependence of the infestation of this pest on spatially distributed micro climatic factors in a rose greenhouse. Despite the importance of this subject, the few existing studies have been realized in laboratory rather than in greenhouse conditions. However, recent progress on greenhouse microclimate characterisation has highlighted the strong indoor climate heterogeneity that may influence the within-crop pest distribution. In this study, both microclimate (air temperature and humidity) and thrips distribution were simultaneously mapped in a rose greenhouse. The measurements were sensed in a horizontal plane situated at mid-height of the rose crop inside the greenhouse. Simultaneously, thrips population dynamics were assessed after an artificial and homogeneous infestation of the rose crop. The spatio-temporal distribution of climate and thrips within the greenhouse were compared, and links between thrips infestation and climatic conditions were investigated. A statistical model was used to define the favourable climate conditions for thrips adults and larvae. Our results showed that (i) the air temperature and air humidity were very heterogeneously distributed within the crop, (ii) pest populations aggregated in the most favourable climatic areas and (iii) the highest population density of thrips adults and larvae were recorded at 27°C and 22°C for temperature and 63% and 86% for humidity, respectively. These findings confirm, in real rose cropping conditions, previous laboratory studies on the F. occidentalis climatic optimum and provide a solid scientific support for climatic-based control methods against this pest. 相似文献
138.
Len J. Wade Violeta Bartolome Ramil Mauleon Vivek Deshmuck Vasant Sumeet Mankar Prabakar Muthukumar Chelliah Emi Kameoka K. Nagendra K. R. Kamalnath Reddy C. Mohan Kumar Varma Kalmeshwar Gouda Patil Roshi Shrestha Zaniab Al-Shugeairy Faez Al-Ogaidi Mayuri Munasinghe Veeresh Gowda Mande Semon Roel R. Suralta Vinay Shenoy Vincent Vadez Rachid Serraj H. E. Shashidhar Akira Yamauchi Ranganathan Chandra Babu Adam Price Kenneth L. McNally Amelia Henry 《PloS one》2015,10(4)
The rapid progress in rice genotyping must be matched by advances in phenotyping. A better understanding of genetic variation in rice for drought response, root traits, and practical methods for studying them are needed. In this study, the OryzaSNP set (20 diverse genotypes that have been genotyped for SNP markers) was phenotyped in a range of field and container studies to study the diversity of rice root growth and response to drought. Of the root traits measured across more than 20 root experiments, root dry weight showed the most stable genotypic performance across studies. The environment (E) component had the strongest effect on yield and root traits. We identified genomic regions correlated with root dry weight, percent deep roots, maximum root depth, and grain yield based on a correlation analysis with the phenotypes and aus, indica, or japonica introgression regions using the SNP data. Two genomic regions were identified as hot spots in which root traits and grain yield were co-located; on chromosome 1 (39.7–40.7 Mb) and on chromosome 8 (20.3–21.9 Mb). Across experiments, the soil type/ growth medium showed more correlations with plant growth than the container dimensions. Although the correlations among studies and genetic co-location of root traits from a range of study systems points to their potential utility to represent responses in field studies, the best correlations were observed when the two setups had some similar properties. Due to the co-location of the identified genomic regions (from introgression block analysis) with QTL for a number of previously reported root and drought traits, these regions are good candidates for detailed characterization to contribute to understanding rice improvement for response to drought. This study also highlights the utility of characterizing a small set of 20 genotypes for root growth, drought response, and related genomic regions. 相似文献
139.
Norinne Lacerda-Queiroz Fatima Brant David Henrique Rodrigues Juliana Priscila Vago Milene Alvarenga Rachid Lirlandia Pires Sousa Mauro Martins Teixeira Antonio Lucio Teixeira 《PloS one》2015,10(3)
Experimental cerebral malaria (ECM) is characterized by a strong immune response, with leukocyte recruitment, blood-brain barrier breakdown and hemorrhage in the central nervous system. Phosphatidylinositol 3-kinase γ (PI3Kγ) is central in signaling diverse cellular functions. Using PI3Kγ-deficient mice (PI3Kγ-/-) and a specific PI3Kγ inhibitor, we investigated the relevance of PI3Kγ for the outcome and the neuroinflammatory process triggered by Plasmodium berghei ANKA (PbA) infection. Infected PI3Kγ-/- mice had greater survival despite similar parasitemia levels in comparison with infected wild type mice. Histopathological analysis demonstrated reduced hemorrhage, leukocyte accumulation and vascular obstruction in the brain of infected PI3Kγ-/- mice. PI3Kγ deficiency also presented lower microglial activation (Iba-1+ reactive microglia) and T cell cytotoxicity (Granzyme B expression) in the brain. Additionally, on day 6 post-infection, CD3+CD8+ T cells were significantly reduced in the brain of infected PI3Kγ-/- mice when compared to infected wild type mice. Furthermore, expression of CD44 in CD8+ T cell population in the brain tissue and levels of phospho-IkB-α in the whole brain were also markedly lower in infected PI3Kγ-/- mice when compared with infected wild type mice. Finally, AS605240, a specific PI3Kγ inhibitor, significantly delayed lethality in infected wild type mice. In brief, our results indicate a pivotal role for PI3Kγ in the pathogenesis of ECM. 相似文献
140.