全文获取类型
收费全文 | 12697篇 |
免费 | 789篇 |
国内免费 | 4篇 |
出版年
2023年 | 110篇 |
2022年 | 98篇 |
2021年 | 195篇 |
2020年 | 195篇 |
2019年 | 201篇 |
2018年 | 431篇 |
2017年 | 389篇 |
2016年 | 525篇 |
2015年 | 804篇 |
2014年 | 777篇 |
2013年 | 968篇 |
2012年 | 1162篇 |
2011年 | 986篇 |
2010年 | 662篇 |
2009年 | 441篇 |
2008年 | 777篇 |
2007年 | 677篇 |
2006年 | 650篇 |
2005年 | 549篇 |
2004年 | 504篇 |
2003年 | 442篇 |
2002年 | 411篇 |
2001年 | 177篇 |
2000年 | 168篇 |
1999年 | 109篇 |
1998年 | 85篇 |
1997年 | 52篇 |
1996年 | 62篇 |
1995年 | 68篇 |
1994年 | 46篇 |
1993年 | 48篇 |
1992年 | 80篇 |
1991年 | 66篇 |
1990年 | 56篇 |
1989年 | 39篇 |
1988年 | 43篇 |
1987年 | 46篇 |
1986年 | 31篇 |
1985年 | 52篇 |
1984年 | 36篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1975年 | 15篇 |
1974年 | 14篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
Four new species ofCayaponia are described and illustrated: three from Brazil (C. cogniauxiana, C. nitida andC. rugosa) and one from Brazil and Bolivia (C. ferruginea). 相似文献
2.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
3.
Valentina Isetta Josep M. Montserrat Raquel Santano Alison J. Wimms Dinesh Ramanan Holger Woehrle Daniel Navajas Ramon Farré 《PloS one》2016,11(3)
Bench testing is a useful method to characterize the response of different automatic positive airway pressure (APAP) devices under well-controlled conditions. However, previous models did not consider the diversity of obstructive sleep apnea (OSA) patients’ characteristics and phenotypes. The objective of this proof-of-concept study was to design a new bench test for realistically simulating an OSA patient’s night, and to implement a one-night example of a typical female phenotype for comparing responses to several currently-available APAP devices. We developed a novel approach aimed at replicating a typical night of sleep which includes different disturbed breathing events, disease severities, sleep/wake phases, body postures and respiratory artefacts. The simulated female OSA patient example that we implemented included periods of wake, light sleep and deep sleep with positional changes and was connected to ten different APAP devices. Flow and pressure readings were recorded; each device was tested twice. The new approach for simulating female OSA patients effectively combined a wide variety of disturbed breathing patterns to mimic the response of a predefined patient type. There were marked differences in response between devices; only three were able to overcome flow limitation to normalize breathing, and only five devices were associated with a residual apnea-hypopnea index of <5/h. In conclusion, bench tests can be designed to simulate specific patient characteristics, and typical stages of sleep, body position, and wake. Each APAP device behaved differently when exposed to this controlled model of a female OSA patient, and should lead to further understanding of OSA treatment. 相似文献
4.
5.
6.
7.
8.
9.
David Gutirrez‐Larruscain Santiago Andrs‐Snchez Enrique Rico María Montserrat Martínez‐Ortega 《植物分类学报:英文版》2019,57(1):42-54
Forty-five populations of Pentanema corresponding to seven species included in the Pentanema conyzae clade have been studied using AFLP fingerprinting. The results show that allopolyploidization could have been involved in the diversification of this group, specifically in species P. langeanum and P. maletii. Molecular data confirm the presence of P. britannicum in the Iberian Peninsula and key steps are provided to identify the species that are morphologically the most challenging. 相似文献
10.