全文获取类型
收费全文 | 1054篇 |
免费 | 85篇 |
出版年
2022年 | 20篇 |
2021年 | 26篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 22篇 |
2016年 | 29篇 |
2015年 | 39篇 |
2014年 | 46篇 |
2013年 | 82篇 |
2012年 | 80篇 |
2011年 | 73篇 |
2010年 | 55篇 |
2009年 | 45篇 |
2008年 | 72篇 |
2007年 | 56篇 |
2006年 | 63篇 |
2005年 | 47篇 |
2004年 | 38篇 |
2003年 | 58篇 |
2002年 | 49篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 4篇 |
排序方式: 共有1139条查询结果,搜索用时 15 毫秒
91.
92.
Morana A Paris O Maurelli L Rossi M Cannio R 《Extremophiles : life under extreme conditions》2007,11(1):123-132
An open reading frame encoding a putative bi-functional β-d-xylosidase/α-l-arabinosidase (Sso3032) was identified on the genome sequence of Sulfolobus solfataricus P2, the predicted gene product showing high amino-acid sequence similarity to bacterial and eukaryal individual β-d-xylosidases and α-l-arabinosidases as well as bi-functional enzymes such as the protein from Thermoanaerobacter ethanolicus and barley. The sequence was PCR amplified from genomic DNA of S. solfataricus P2 and heterologous gene expression obtained in Escherichia coli, under optimal conditions for overproduction. Specific assays performed at 75°C revealed the presence in the transformed
E. coli cell extracts of this archaeal activity involved in sugar hydrolysis and specific for both substrates. The recombinant protein
was purified by thermal precipitation of the host proteins and ethanol fractionation and other properties, such as high thermal
activity and thermostability could be determined. The protein showed a homo-tetrameric structure with a subunit of molecular
mass of 82.0 kDa which was in perfect agreement with that deduced from the cloned gene. Northern blot analysis of the xarS gene indicates that it is specifically induced by xylan and repressed by monosaccharides like d-glucose and l-arabinose. 相似文献
93.
Ricci Giannina Campanini Emeline Boni Nishikaku Angela Satie Puccia Rosana Marques Mariângela Bialek Ralf Rodrigues Anderson Messias Batista Wagner Luiz 《Mycopathologia》2022,187(2-3):157-168
Mycopathologia - Paracoccidioidomycosis (PCM) is a systemic mycosis caused by a group of cryptic species embedded in the Paracoccidioides brasiliensis complex and Paracoccidioides lutzii. Four... 相似文献
94.
Bice Avallone Claudio Agnisola Raimondo Cerciello Raffaele Panzuto Palma Simoniello Patrizia Cretì Chiara Maria Motta 《Cell biology and toxicology》2015,31(6):273-283
This report describes the alterations induced by an environmentally realistic concentration of cadmium in skeletal muscle fibre organization, composition, and function in the teleost zebrafish. Results demonstrate that the ion induces a significant quantitative and qualitative deterioration, disrupting sarcomeric pattern and altering glycoprotein composition. These events, together with a mitochondrial damage, result in a significant reduction in swimming performance. In conclusion, the evidence here collected indicate that in presence of an environmental cadmium contamination, important economic (yields in fisheries/aquaculture), consumer health (fish is an important source of proteins), and ecological (reduced fitness due to reduced swimming performance) consequences can be expected. 相似文献
95.
Abundance,diversity and geographic distribution of cassava mosaic disease pandemic‐associated Bemisia tabaci in Tanzania
下载免费PDF全文
![点击此处可从《Journal of Applied Entomology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
L. S. Tajebe S. B. Boni D. Guastella V. Cavalieri O. S. Lund C. P. Rugumamu C. Rapisarda J. P. Legg 《Journal of Applied Entomology》2015,139(8):627-637
Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), one of the most economically important agricultural pests worldwide, is the vector of cassava mosaic geminiviruses that cause cassava mosaic disease (CMD). In East and Central Africa, a severe CMD pandemic that spread from Uganda in the late 1980s still continues to devastate cassava crops. To assess the association of distinct B. tabaci genetic groups with the CMD pandemic, mitochondrial cytochrome oxidase I gene sequences were analysed from whiteflies collected during surveys conducted from 2010 to 2013 in Tanzania. Four genetic groups – Sub‐Saharan Africa 1 (SSA1), Mediterranean, Indian Ocean and East Africa 1, and a group of unknown whitefly species were identified. SSA1 comprised four subgroups: SSA1‐SG1, SSA1‐SG2, SSA1‐SG1/2 and SSA1‐SG3. SSA1‐SG1 was confined to the pandemic‐affected north‐western parts of Tanzania whilst SSA1‐SG2 and SSA1‐SG3 were found in the central and eastern parts not yet affected by the pandemic. The CMD pandemic front was estimated to lie in Geita Region, north‐western Tanzania, and to be spreading south‐east at a rate of ca 26 km/year. The pandemic‐associated B. tabaci SSA1‐SG1 predominated up to 180 km ahead of the CMD front indicating that changes in whitefly population characteristics precede changes in disease characteristics. 相似文献
96.
97.
98.
DNA microarray is a powerful tool for the parallel of nucleic acids and other biologically significant molecules. In this communication we report an easy and cheap synthesis route for incorporating organic dyes into monodisperse inorganic silica nanoparticles and their application on the detection of carcinogenic risky Human Papilloma Virus using DNA microarray technology. We correlate our system with conventional direct dyes and commercial quantum dots, with a promising increase in optical signal, and a related decrease of the limit of detection, thus giving a remarkable improvement in this technique towards early diagnosis of diseases and trace level detection of dangerous biological contaminants. 相似文献
99.
Performance of a mobile mechanical screen to improve the commercial quality of wood chips for energy 总被引:1,自引:0,他引:1
The study analyzed the performance of a mobile screening device for upgrading coarse wood chips to residential user standards, by removing oversize particles and fines. The machine was designed for transportation to forest landings, logistic terminals and plant chip yards. Average productivity was 1.9 oven-dry tons (odt) h−1, corresponding to a screening cost of 28.5 € odt−1. This figure was lower than the price increase obtained by upgrading industrial chips to residential user standards. Hence, screening offered a profit of 4.7 € odt−1, or 16% of the original screening cost. The screening process was capable of upgrading chips from industrial to residential specifications, by reducing the incidence of oversize particles below the 1% critical threshold. Screening also allowed a substantial reduction in the content of fines. A similar effect was not verified for crushed wood, which failed to meet the specifications for residential fuel. 相似文献
100.