全文获取类型
收费全文 | 369篇 |
免费 | 14篇 |
国内免费 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 10篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 16篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 3篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1983年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1959年 | 7篇 |
1958年 | 23篇 |
1957年 | 26篇 |
1956年 | 26篇 |
1955年 | 22篇 |
1954年 | 22篇 |
1953年 | 13篇 |
1952年 | 13篇 |
1951年 | 10篇 |
1950年 | 9篇 |
1949年 | 2篇 |
1948年 | 2篇 |
1946年 | 1篇 |
1938年 | 1篇 |
1912年 | 2篇 |
排序方式: 共有393条查询结果,搜索用时 46 毫秒
381.
M. ALICIA DE LA COLINA BETTINA MAHLER JUAN CARLOS REBOREDA 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(4):838-845
Genetic differentiation among shiny cowbird (Molothrus bonariensis) females that use different hosts indicates that in this brood parasite, host use is not random at an individual level. We tested whether there exist differences in morphology and coloration between eggs of shiny cowbirds laid in the nests of two different hosts, the chalk‐browed mockingbird (Mimus saturninus) and the house wren (Troglodytes aedon). We took morphometric measures of shiny cowbird eggs found in nests of mockingbirds and wrens and analysed their coloration using digital photography and reflectance spectrometry. We found that shiny cowbird eggs found in mockingbird nests were wider and more asymmetric than those found in wren nests. In addition, cowbird eggs coming from mockingbird nests were brighter and had higher relative red reflectance than those coming from wren nests. Our results show that shiny cowbird eggs laid in nests of two different hosts vary in shape and background colour, but not in spotting pattern. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 838–845. 相似文献
382.
383.
384.
In the experiments to be described two congenic inbred lines CB and CC and two recombinant lines CB.R1 and CC.R1 were used. All four lines differ only in regard to the major histocompatibility complex (MHC). To determine the percentage distributions of the two cell subsets in peripheral blood lymphocytes (PBL) in these lines, monoclonal antibodies to these two antigens were used. By FACScan there were more CD4+PBL in CB and CB.R1 lines (share B-F/B-L region, controlling class I/class II antigens with line CB) than CC and CC.R1, while the reverse was true with CD8+ subsets. There were more CD8+ PBL in the CC and CC.R1 lines and less in CB and CB.R1 lines. The ratio of CD4+ to CD8+ in CB chickens was 3.4 +/- 0.2 and in CC chickens 1.6 +/- 0.1. 相似文献
385.
386.
GUSTAVO YA
EZ-OCAMPO MARTHA E. MORA-HERRERA ARNOLDO WONG-VILLARREAL DENISSE M. DE LA PAZ-OSORIO NADIA DE LA PORTILLA-L
PEZ JORGE LUGO ROCIO VACA-PAULÍN PEDRO DEL GUILA 《Polish journal of microbiology》2020,69(3):357
The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.Key words: Bacillus sp., phosphorus soluble, Pikovskaya agar, potato rhizosphere, plant growth promoting rhizobacteria 相似文献
387.
388.
First molecular identification of the vertebrate hosts of Culicoides imicola in Europe and a review of its blood‐feeding patterns worldwide: implications for the transmission of bluetongue disease and African horse sickness
下载免费PDF全文
![点击此处可从《Medical and veterinary entomology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J. MARTÍNEZ‐DE LA PUENTE J. NAVARRO M. FERRAGUTI R. SORIGUER J. FIGUEROLA 《Medical and veterinary entomology》2017,31(4):333-339
Culicoides (Diptera: Ceratopogonidae) are vectors of pathogens that affect wildlife, livestock and, occasionally, humans. Culicoides imicola (Kieffer, 1913) is considered to be the main vector of the pathogens that cause bluetongue disease (BT) and African horse sickness (AHS) in southern Europe. The study of blood‐feeding patterns in Culicoides is an essential step towards understanding the epidemiology of these pathogens. Molecular tools that increase the accuracy and sensitivity of traditional methods have been developed to identify the hosts of potential insect vectors. However, to the present group's knowledge, molecular studies that identify the hosts of C. imicola in Europe are lacking. The present study genetically characterizes the barcoding region of C. imicola trapped on farms in southern Spain and identifies its vertebrate hosts in the area. The report also reviews available information on the blood‐feeding patterns of C. imicola worldwide. Culicoides imicola from Spain feed on blood of six mammals that include species known to be hosts of the BT and AHS viruses. This study provides evidence of the importance of livestock as sources of bloodmeals for C. imicola and the relevance of this species in the transmission of BT and AHS viruses in Europe. 相似文献
389.
390.
LA Tziveleka D Abatis K Paulus R Bauer C Vagias V Roussis 《Chemistry & biodiversity》2005,2(7):901-909
A series of polyprenylated hydroquinones, quinones, and chromenols were isolated from the extracts of the marine sponge Ircinia spinosula and the brown alga Taonia atomaria, which gave rise to the constituents 1-4 and 5-8, respectively. Compounds 1, 2, 6, and 7 are new natural products, which were fully characterized. Their anti-inflammatory activities in terms of leukotriene formation were evaluated in an in vitro assay with pork leukocytes. The new hydroxylated compound, 2'-[28-hydroxy]heptaprenyl-1',4'-hydroquinone (= 2-[(2E,6E,10E,14E,18Z,22E)-19-(hydroxymethyl)-3,7,11,15,23,27-hexamethyloctacosa-2,6,10,14,18,22,26-heptaen-1-yl]benzene-1,4-diol; 1), the known tetraprenyl benzoquinone sargaquinone (5), and the known polyprenyl chromenols 3 and 4 exhibited the highest anti-inflammatory activities, with IC50 values of 1.9-9.4 microM (Table 3). Potential structure-activity relationships (SAR) are discussed. 相似文献