全文获取类型
收费全文 | 1761篇 |
免费 | 95篇 |
国内免费 | 1篇 |
专业分类
林业 | 228篇 |
农学 | 56篇 |
基础科学 | 11篇 |
446篇 | |
综合类 | 188篇 |
农作物 | 67篇 |
水产渔业 | 76篇 |
畜牧兽医 | 564篇 |
园艺 | 47篇 |
植物保护 | 174篇 |
出版年
2023年 | 16篇 |
2022年 | 27篇 |
2021年 | 36篇 |
2020年 | 42篇 |
2019年 | 38篇 |
2018年 | 53篇 |
2017年 | 70篇 |
2016年 | 46篇 |
2015年 | 41篇 |
2014年 | 51篇 |
2013年 | 79篇 |
2012年 | 112篇 |
2011年 | 136篇 |
2010年 | 78篇 |
2009年 | 79篇 |
2008年 | 115篇 |
2007年 | 111篇 |
2006年 | 81篇 |
2005年 | 84篇 |
2004年 | 72篇 |
2003年 | 74篇 |
2002年 | 72篇 |
2001年 | 29篇 |
2000年 | 15篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 23篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1981年 | 6篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1970年 | 8篇 |
排序方式: 共有1857条查询结果,搜索用时 15 毫秒
971.
Jean Guyot Christian Cilas Ivan Sache 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(2):111-124
South American leaf blight (SALB), the most dangerous disease of the rubber tree, is responsible for the lack of significant
natural rubber production in South America and is a major threat to rubber tree plantations in Asia and Africa. Although the
selection of resistant clones is the preferred disease control method, greater knowledge is required of the relationship between
host and pathogen, in order to construct more durable resistance. Based on small-scale trials, this study set out to compare
the dynamics of SALB on two highly susceptible and one moderately susceptible clone and to analyse the effect of host phenology
on disease severity, at leaflet and flush scales. Clonal resistance was found to have a noticeable effect on disease severity,
asexual sporulation and stromatal density at both leaflet and flush levels, and on disease dynamics at a leaflet level; time
for symptom and sporulation appearance were longer on the moderately susceptible clone than on the susceptible clones. On
the moderately susceptible clone, the stromatal density was largely dependent on disease severity. The phenology did not differ
among the three clones and could not be considered as a factor in genetic resistance to SALB. However, for the three clones,
the position of the leaflet in the flush affected the duration of the immature stages and the disease: the shorter the duration
of leaflet development, the lower the disease severity, the sporulation intensity and the stromatal density. 相似文献
972.
Bettina Welke Inga Mewis Tanja Mucha-Pelzer Arunava Goswami Christian Ulrichs 《Gesunde Pflanzen》2008,60(1):15-21
The present work deals with a new strategy to control Eriosoma lanigerum (Hausm.) in apple and Forficula auricularia?(L.) in apricots. With common insecticides, both pests are difficult to control. Although F.?auricularia is regarded as a beneficial insect, in ecological agriculture it has the potential to cause severe economical damage in apricots. In apple and apricot orchards we tested treatments on the bark with diatomaceous earth (DE) products to prevent insects from reaching the tree crown. DE has been applied as liquid (“Fossil Shield®” translucend) by a backpack sprayer or electrostatically as powder (“Fossil Shield®” 90.0?s). In some trials we covered the treated area with a plastic funnel (fruitcap) in order to protect the silica-product from wind and rain. Experiments were evaluated weekly and number of insects in the tree crown was counted. During the first two months after treatment E.?lanigerum population in the crown was reduced by 98.2%. However, over the whole period of six month the barriers turned out to be ineffective (p?=?0.617). Winged adults have been capable to pass the barriere. In contrast to this fruitcap barriers were able to keep F. auricularia away from the crown (p?=?0.000). They have been as effective as standard treatment using glue. In such treatments apricot yield increased 6-fold for the cultivar “Goldrich” and 5.5-fold for the cultivar “Hargrand”. 相似文献
973.
974.
Evaluation of the immune response in rainbow trout fry,Oncorhynchus mykiss (Walbaum), after waterborne exposure to Flavobacterium psychrophilum and/or hydrogen peroxide
下载免费PDF全文
![点击此处可从《Journal of fish diseases》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The immune response in rainbow trout fry against Flavobacterium psychrophilum was elucidated using an immersion‐based challenge with or without prior exposure to hydrogen peroxide (H2O2). Samples were taken from the head kidney 4, 48, 125 and 192 h after immersion, and the regulation of several genes was examined. Bacterial load was assessed based on the presence of 16S rRNA and correlated with gene expression, and the levels of specific antibodies in the blood were measured 50 days post‐infection. Separately, both H2O2 and F. psychrophilum influenced gene expression, and pre‐treatment with H2O2 influenced the response to infection with F. psychrophilum. Pre‐treatment with H2O2 also affected correlation between gene regulation and pathogen load for several genes. A delay in antibody production in H2O2‐treated fish in the early phase of infection was indicated, but H2O2 exposure did not affect antibody levels 50 days post‐infection. An increasing amount of F. psychrophilum 16S rRNA was found in the head kidneys of infected fish pre‐treated with H2O2 relative to the F. psychrophilum group. The results show that a single pre‐treatment with H2O2 impairs the response against F. psychrophilum and may intensify infection. 相似文献
975.
Paul G. Wahome Kevin R. Beauchesne Anna C. Pedone John Cavanagh Christian Melander Paul Zimba Peter D. R. Moeller 《Marine drugs》2015,13(1):65-75
Aquatic microbes produce diverse secondary metabolites with interesting biological activities. Cytotoxic metabolites have the potential to become lead compounds or drugs for cancer treatment. Many cytotoxic compounds, however, show undesirable toxicity at higher concentrations. Such undesirable activity may be reduced or eliminated by using lower doses of the cytotoxic compound in combination with another compound that modulates its activity. Here, we have examined the cytotoxicity of four microbial metabolites [ethyl N-(2-phenethyl) carbamate (NP-1), Euglenophycin, Anabaenopeptin, and Glycolipid 652] using three in vitro cell lines [human breast cancer cells (MCF-7), mouse neuroblastoma cells (N2a), and rat pituitary epithelial cells (GH4C1)]. The compounds showed variable cytotoxicity, with Euglenophycin displaying specificity for N2a cells. We have also examined the modulatory power of NP-1 on the cytotoxicity of the other three compounds and found that at a permissible concentration (125 µg/mL), NP-1 sensitized N2a and MCF-7 cells to Euglenophycin and Glycolipid 652 induced cytotoxicity. 相似文献
976.
977.
Calluna vulgaris is an important landscaping plant in Northern Europe. As C. vulgaris is the only species within the genus Calluna, the available gene-pool for breeding is rather narrow and phenotypic variation is limited. Hence, a breeding program for polyploids was set up in order to broaden phenotypic variation in this important ornamental crop. Therefor basic genetic characteristics of polyploid C. vulgaris were analyzed using the progeny of a spontaneously occurring tetraploid genotype. With the help of morphological and molecular marker analysis, it was determined that the autotetraploid plant probably arose from unreduced gametes resulting from first division restitution. Tetraploids displayed tetrasomic inheritance with free combination of homologous and homeologous chromosomes. Triploids were semi-fertile with a high rate of aneuploids in their progeny. As the so-called bud-blooming flower type is a trait of outstanding interest in breeding of C. vulgaris, a strategy for efficient breeding of triploid bud-bloomers was deduced. 相似文献
978.
Christian Nansen 《Pest management science》2016,72(4):653-659
Bench‐top or proximal remote sensing applications are widely used as part of quality control and machine vision systems in commercial operations. In addition, these technologies are becoming increasingly important in insect systematics and studies of insect physiology and pest management. This paper provides a review and discussion of how proximal remote sensing may contribute valuable quantitative information regarding identification of species, assessment of insect responses to insecticides, insect host responses to parasitoids and performance of biological control agents. The future role of proximal remote sensing is discussed as an exciting path for novel paths of multidisciplinary research among entomologists and scientists from a wide range of other disciplines, including image processing engineers, medical engineers, research pharmacists and computer scientists. © 2015 Society of Chemical Industry 相似文献
979.
980.