全文获取类型
收费全文 | 19997篇 |
免费 | 1834篇 |
国内免费 | 19篇 |
出版年
2022年 | 131篇 |
2021年 | 264篇 |
2020年 | 133篇 |
2019年 | 207篇 |
2018年 | 262篇 |
2017年 | 206篇 |
2016年 | 382篇 |
2015年 | 674篇 |
2014年 | 750篇 |
2013年 | 929篇 |
2012年 | 1206篇 |
2011年 | 1275篇 |
2010年 | 771篇 |
2009年 | 673篇 |
2008年 | 967篇 |
2007年 | 1076篇 |
2006年 | 991篇 |
2005年 | 983篇 |
2004年 | 971篇 |
2003年 | 945篇 |
2002年 | 921篇 |
2001年 | 216篇 |
2000年 | 146篇 |
1999年 | 213篇 |
1998年 | 266篇 |
1997年 | 191篇 |
1996年 | 174篇 |
1995年 | 204篇 |
1994年 | 183篇 |
1993年 | 172篇 |
1992年 | 170篇 |
1991年 | 147篇 |
1990年 | 139篇 |
1989年 | 134篇 |
1988年 | 140篇 |
1987年 | 139篇 |
1986年 | 138篇 |
1985年 | 159篇 |
1984年 | 180篇 |
1983年 | 151篇 |
1982年 | 217篇 |
1981年 | 224篇 |
1980年 | 224篇 |
1979年 | 143篇 |
1978年 | 149篇 |
1977年 | 134篇 |
1976年 | 164篇 |
1975年 | 124篇 |
1974年 | 137篇 |
1973年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
51.
Christine E. Brown Charles D. Warden Renate Starr Xutao Deng Behnam Badie Yate-Ching Yuan Stephen J. Forman Michael E. Barish 《PloS one》2013,8(10)
A major challenge for successful immunotherapy against glioma is the identification and characterization of validated targets. We have taken a bioinformatics approach towards understanding the biological context of IL-13 receptor α2 (IL13Rα2) expression in brain tumors, and its functional significance for patient survival. Querying multiple gene expression databases, we show that IL13Rα2 expression increases with glioma malignancy grade, and expression for high-grade tumors is bimodal, with approximately 58% of WHO grade IV gliomas over-expressing this receptor. By several measures, IL13Rα2 expression in patient samples and low-passage primary glioma lines most consistently correlates with the expression of signature genes defining mesenchymal subclass tumors and negatively correlates with proneural signature genes as defined by two studies. Positive associations were also noted with proliferative signature genes, whereas no consistent associations were found with either classical or neural signature genes. Probing the potential functional consequences of this mesenchymal association through IPA analysis suggests that IL13Rα2 expression is associated with activation of proinflammatory and immune pathways characteristic of mesenchymal subclass tumors. In addition, survival analyses indicate that IL13Rα2 over-expression is associated with poor patient prognosis, a single gene correlation ranking IL13Rα2 in the top ~1% of total gene expression probes with regard to survival association with WHO IV gliomas. This study better defines the functional consequences of IL13Rα2 expression by demonstrating association with mesenchymal signature gene expression and poor patient prognosis. It thus highlights the utility of IL13Rα2 as a therapeutic target, and helps define patient populations most likely to respond to immunotherapy in present and future clinical trials. 相似文献
52.
53.
54.
Nina Fudge Charles D A Wolfe Christopher McKevitt 《BMJ (Clinical research ed.)》2008,336(7639):313-317
Objectives To understand how the policy of user involvement is interpreted in health service organisations and to identify factors that influence how user involvement is put into practice.Design Ethnographic study using participant observation, interviews, and collection of documentary evidence.Setting A multiagency modernisation programme to improve stroke services in two London boroughs.Participants Service users, National Health Service managers, and clinicians.Results User involvement in the programme was initiated and led by professionals. Professionals determined the areas of service improvement service users could participate in. A wide range of activities were considered “user involvement,” from patient satisfaction surveys to service users delivering peer support. Involvement tended to be most active in the least technical areas and areas with least input from clinicians. Factors that might explain this included organisational structure, the vagueness of the concept of user involvement, the value attributed to service users’ experiential knowledge, and variations in professional and service user understandings of and commitment to involvement. The gains of involvement were harder to identify in terms of impact on services. More evident were the personal gains for those involved: satisfaction of feeling listened to by professionals, social opportunities of meeting others in a similar situation, and increased knowledge about stroke and services available.Conclusions User involvement may not automatically lead to improved service quality. Healthcare professionals and service users understand and practise user involvement in different ways according to individual ideologies, circumstances, and needs. Given the resource implications of undertaking user involvement in service development there is a need for critical debate on the purpose of such involvement as well as better evidence of the benefits claimed for it. 相似文献
55.
56.
Numerous functional ergatoid replacement reproductives were found in one colony of Nasutitermes columbicus in Panama. Their morphology was mainly workerlike, although several imaginal characters such as the compound eyes and variable wing buds were more or less developed. The sex organs were fully mature and the fat body of the females, not of the males, was of the “royal” type. The development of the eyes was not accompanied by the differentiation of the optic lobes of the brain, nor was the presence of wing buds correlated with a development of the wing muscles. 相似文献
57.
58.
59.
60.