全文获取类型
收费全文 | 3177篇 |
免费 | 161篇 |
专业分类
3338篇 |
出版年
2024年 | 8篇 |
2023年 | 18篇 |
2022年 | 46篇 |
2021年 | 74篇 |
2020年 | 46篇 |
2019年 | 51篇 |
2018年 | 63篇 |
2017年 | 59篇 |
2016年 | 99篇 |
2015年 | 180篇 |
2014年 | 176篇 |
2013年 | 216篇 |
2012年 | 303篇 |
2011年 | 319篇 |
2010年 | 179篇 |
2009年 | 167篇 |
2008年 | 176篇 |
2007年 | 150篇 |
2006年 | 117篇 |
2005年 | 128篇 |
2004年 | 149篇 |
2003年 | 112篇 |
2002年 | 91篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 16篇 |
1998年 | 30篇 |
1997年 | 23篇 |
1996年 | 19篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 25篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1973年 | 12篇 |
1972年 | 8篇 |
排序方式: 共有3338条查询结果,搜索用时 15 毫秒
81.
Molecular characterization of two lipoxygenases from barley 总被引:4,自引:0,他引:4
82.
Noa Safra Louisa J. Hayward Miriam Aguilar Benjamin N. Sacks Jodi L. Westropp F. Charles Mohr Cathryn S. Mellersh Danika L. Bannasch 《PloS one》2015,10(8)
The aim of this study was to investigate the frequency of regional DNA variants upstream to the translation initiation site of the canine Cyclooxygenase-2 (Cox-2) gene in healthy dogs. Cox-2 plays a role in various disease conditions such as acute and chronic inflammation, osteoarthritis and malignancy. A role for Cox-2 DNA variants in genetic predisposition to canine renal dysplasia has been proposed and dog breeders have been encouraged to select against these DNA variants. We sequenced 272–422 bases in 152 dogs unaffected by renal dysplasia and found 19 different haplotypes including 11 genetic variants which had not been described previously. We genotyped 7 gray wolves to ascertain the wildtype variant and found that the wolves we analyzed had predominantly the second most common DNA variant found in dogs. Our results demonstrate an elevated level of regional polymorphism that appears to be a feature of healthy domesticated dogs. 相似文献
83.
Tatiana Vernié Jiyoung Kim Lisa Frances Yiliang Ding Jongho Sun Dian Guan Andreas Niebel Miriam L. Gifford Fernanda de Carvalho-Niebel Giles E.D. Oldroyd 《The Plant cell》2015,27(12):3410-3424
Biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following Nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. We show that while early Nod factor signaling associated with calcium oscillations is limited to the root surface, the resultant activation of Nodule Inception (NIN) in the root epidermis is sufficient to promote cytokinin signaling and nodule organogenesis in the inner root cortex. NIN or a product of its action must be associated with the transmission of a signal between the root surface and the cortical cells where nodule organogenesis is initiated. NIN appears to have distinct functions in the root epidermis and the root cortex. In the epidermis, NIN restricts the extent of Early Nodulin 11 (ENOD11) expression and does so through competitive inhibition of ERF Required for Nodulation (ERN1). In contrast, NIN is sufficient to promote the expression of the cytokinin receptor Cytokinin Response 1 (CRE1), which is restricted to the root cortex. Our work in Medicago truncatula highlights the complexity of NIN action and places NIN as a central player in the coordination of the symbiotic developmental programs occurring in differing tissues of the root that combined are necessary for a nitrogen-fixing symbiosis. 相似文献
84.
85.
Viral Co-Infections in Pediatric Patients Hospitalized with Lower Tract Acute Respiratory Infections
Miriam Cebey-López Jethro Herberg Jacobo Pardo-Seco Alberto Gómez-Carballa Nazareth Martinón-Torres Antonio Salas José María Martinón-Sánchez Stuart Gormley Edward Sumner Colin Fink Federico Martinón-Torres GENDRES network 《PloS one》2015,10(9)
Background
Molecular techniques can often reveal a broader range of pathogens in respiratory infections. We aim to investigate the prevalence and age pattern of viral co-infection in children hospitalized with lower tract acute respiratory infection (LT-ARI), using molecular techniques.Methods
A nested polymerase chain reaction approach was used to detect Influenza (A, B), metapneumovirus, respiratory syncytial virus (RSV), parainfluenza (1–4), rhinovirus, adenovirus (A—F), bocavirus and coronaviruses (NL63, 229E, OC43) in respiratory samples of children with acute respiratory infection prospectively admitted to any of the GENDRES network hospitals between 2011–2013. The results were corroborated in an independent cohort collected in the UK.Results
A total of 204 and 97 nasopharyngeal samples were collected in the GENDRES and UK cohorts, respectively. In both cohorts, RSV was the most frequent pathogen (52.9% and 36.1% of the cohorts, respectively). Co-infection with multiple viruses was found in 92 samples (45.1%) and 29 samples (29.9%), respectively; this was most frequent in the 12–24 months age group. The most frequently observed co-infection patterns were RSV—Rhinovirus (23 patients, 11.3%, GENDRES cohort) and RSV—bocavirus / bocavirus—influenza (5 patients, 5.2%, UK cohort).Conclusion
The presence of more than one virus in pediatric patients admitted to hospital with LT-ARI is very frequent and seems to peak at 12–24 months of age. The clinical significance of these findings is unclear but should warrant further analysis. 相似文献86.
Sara C. Johnston Kenny L. Lin Nancy A. Twenhafel Jo Lynne W. Raymond Joshua D. Shamblin Suzanne E. Wollen Carly B. Wlazlowski Eric R. Wilkinson Miriam A. Botto Arthur J. Goff 《PloS one》2015,10(9)
Marburg virus infection in humans causes a hemorrhagic disease with a high case fatality rate. Countermeasure development requires the use of well-characterized animal models that mimic human disease. To further characterize the cynomolgus macaque model of MARV/Angola, two independent dose response studies were performed using the intramuscular or aerosol routes of exposure. All animals succumbed at the lowest target dose; therefore, a dose effect could not be determined. For intramuscular-exposed animals, 100 PFU was the first target dose that was not significantly different than higher target doses in terms of time to disposition, clinical pathology, and histopathology. Although a significant difference was not observed between aerosol-exposed animals in the 10 PFU and 100 PFU target dose groups, 100 PFU was determined to be the lowest target dose that could be consistently obtained and accurately titrated in aerosol studies. 相似文献
87.
88.
89.
90.
Nicole Werner Miriam Dreyer Wenke Wagner Nicolas Papon Steffen Rupp Susanne Zibek 《Biotechnology letters》2017,39(3):429-438