全文获取类型
收费全文 | 515篇 |
免费 | 30篇 |
国内免费 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 18篇 |
2014年 | 28篇 |
2013年 | 37篇 |
2012年 | 35篇 |
2011年 | 28篇 |
2010年 | 16篇 |
2009年 | 24篇 |
2008年 | 17篇 |
2007年 | 24篇 |
2006年 | 33篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有546条查询结果,搜索用时 15 毫秒
21.
AB Zarafi AM Emechebe AD Akpa O Alabi 《Archives Of Phytopathology And Plant Protection》2013,46(4):261-268
Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight. 相似文献
22.
Zi-Feng Jiang Fangfang Xia Kipp W. Johnson Christopher D. Brown Elizabeth Bartom Jigyasa H. Tuteja Rick Stevens Robert L. Grossman Marina Brumin Kevin P. White Murad Ghanim 《Applied and environmental microbiology》2013,79(5):1757-1759
“Candidatus Portiera aleyrodidarum” is the primary endosymbiont of whiteflies. We report two complete genome sequences of this bacterium from the worldwide invasive B and Q biotypes of the whitefly Bemisia tabaci. Differences in the two genome sequences may add insights into the complex differences in the biology of both biotypes. 相似文献
23.
Oreenaiza Nordin Wesley Donald Wong Hong Ming Teoh Guat Ney Khairul Asuad Mohamed Nor Azlina Abdul Halim Peter Winskill Azahari Abdul Hadi Zulkamal Safi'in Muhammad Renaud Lacroix Sarah Scaife Andrew Robert McKemey Camilla Beech Murad Shahnaz Luke Alphey Derric David Nimmo Wasi Ahmed Nazni Han Lim Lee 《PloS one》2013,8(3)
Dengue is the most important mosquito-borne viral disease. No specific treatment or vaccine is currently available; traditional vector control methods can rarely achieve adequate control. Recently, the RIDL (Release of Insect carrying Dominant Lethality) approach has been developed, based on the sterile insect technique, in which genetically engineered ‘sterile’ homozygous RIDL male insects are released to mate wild females; the offspring inherit a copy of the RIDL construct and die. A RIDL strain of the dengue mosquito, Aedes aegypti, OX513A, expresses a fluorescent marker gene for identification (DsRed2) and a protein (tTAV) that causes the offspring to die. We examined whether these proteins could adversely affect predators that may feed on the insect. Aedes aegypti is a peri-domestic mosquito that typically breeds in small, rain-water-filled containers and has no specific predators. Toxorhynchites larvae feed on small aquatic organisms and are easily reared in the laboratory where they can be fed exclusively on mosquito larvae. To evaluate the effect of a predator feeding on a diet of RIDL insects, OX513A Ae. aegypti larvae were fed to two different species of Toxorhynchites (Tx. splendens and Tx. amboinensis) and effects on life table parameters of all life stages were compared to being fed on wild type larvae. No significant negative effect was observed on any life table parameter studied; this outcome and the benign nature of the expressed proteins (tTAV and DsRed2) indicate that Ae. aegypti OX513A RIDL strain is unlikely to have any adverse effects on predators in the environment. 相似文献
24.
25.
26.
27.
Sanjana Iyengar Paula R. Williamson Jochen Schmitt Lena Johannsen Ian A. Maher Joseph F. Sobanko Todd V. Cartee Daniel Schlessinger Emily Poon Murad Alam 《Trials》2016,17(1)
BackgroundRosacea is a chronic inflammatory disorder affecting millions of individuals worldwide. Diagnosis is based on signs and symptoms with management and treatment aimed to suppress inflammatory lesions, erythema, and telangiectasia. While many clinical trials of rosacea exist, the lack of consensus in outcome reporting across all trials poses a concern. Proper evaluation and comparison of treatment modalities is challenging. In order to address the inconsistencies present, this project aims to determine a core set of outcomes which should be evaluated in all clinical trials of rosacea.Methods/designThis project will utilize a methodology similar to previous core outcome set research. A long list of outcomes will be extracted over four phases: (1) systematic literature review, (2) patient interviews, (3) other published sources, and (4) stakeholder involvement. Potential outcomes will be examined by the Steering Committee to provide further insight. The Delphi process will then be performed to prioritize and condense the list of outcomes generated. Two homogenous groups of physicians and patients will participate in two consecutive rounds of Delphi surveys. A consensus meeting, composed of physicians, patients, and stakeholders, will be conducted after the Delphi exercise to further select outcomes, taking into account participant scores. By the end of the meeting, members will vote and decide on a final recommended set of core outcomes. For the duration of the study, we will be in collaboration with both the Core Outcome Measures in Effectiveness Trials (COMET) and Cochrane Skin Group - Core Outcome Set Initiative (CSG-COUSIN).DiscussionThis study aims to develop a core outcome set to guide assessment in clinical trials of rosacea. The end-goal is to improve the reliability and consistency of outcome reporting, thereby allowing sufficient evaluation of treatment effectiveness and patient satisfaction.
Electronic supplementary material
The online version of this article (doi:10.1186/s13063-016-1554-3) contains supplementary material, which is available to authorized users. 相似文献28.
29.
Zhang Meng Demeshko Yonatan Dumbur Rita Iven Tim Feussner Ivo Lebedov Galina Ganim Murad Barg Rivka Ben-Hayyim Gozal 《Journal of Plant Growth Regulation》2019,38(2):723-738
Journal of Plant Growth Regulation - In tomato, desaturation of linoleic acid (18:2) to α-linolenic acid (18:3) is mediated in the plastidial membranes by the ω-3 fatty acid desaturases 7... 相似文献
30.
Marchal LM van de Laar AM Goetheer E Schimmelpennink EB Bergsma J Beeftink HH Tramper J 《Biotechnology and bioengineering》1999,63(3):344-355
The hydrolysis of starch to low-molecular-weight products (normally characterised by their dextrose equivalent (DE), which is directly related to the number-average molecular mass) was studied at different temperatures. Amylopectin potato starch, lacking amylose, was selected because of its low tendency towards retrogradation at lower temperatures. Bacillus licheniformis alpha-amylase was added to 10% [w/w] gelatinised starch solutions. The hydrolysis experiments were done at 50, 70, and 90 degrees C. Samples were taken at defined DE values and these were analysed with respect to their saccharide composition. At the same DE the oligosaccharide composition depended on the hydrolysis temperature. This implies that at the same net number of bonds hydrolysed by the enzyme, the saccharide composition was different. The hydrolysis temperature also influenced the initial overall molecular-weight distribution. Higher temperatures led to a more homogenous molecular weight distribution. Similar effects were observed for alpha-amylases from other microbial sources such as Bacillus amyloliquefaciens and Bacillus stearothermophilus. Varying the pH (5.1, 6.2, and 7.6) at 70 degrees C did not significantly influence the saccharide composition obtained during B. licheniformis alpha-amylase hydrolysis. The underlying mechanisms for B. licheniformis alpha-amylase were studied using pure linear oligosaccharides, ranging from maltotriose to maltoheptaose as substrates. Activation energies for the hydrolysis of individual oligosaccharides were calculated from Arrhenius plots at 60, 70, 80, and 90 degrees C. Oligosaccharides with a degree of polymerisation exceeding that of the substrate could be detected. The contribution of these oligosaccharides increased as the degree of polymerisation of the substrate decreased and the temperature of hydrolysis increased. The product specificity decreased with increasing temperature of hydrolysis, which led to a more equal distribution between the possible products formed. Calculations with the subsite map as determined for the closely related alpha-amylase from B. amyloliquefaciens reconfirmed this finding of a decreased substrate specificity with increased temperature of hydrolysis. Copyright 1999 John Wiley & Sons, Inc. 相似文献