全文获取类型
收费全文 | 4105篇 |
免费 | 386篇 |
国内免费 | 237篇 |
出版年
2024年 | 3篇 |
2023年 | 37篇 |
2022年 | 116篇 |
2021年 | 208篇 |
2020年 | 123篇 |
2019年 | 160篇 |
2018年 | 176篇 |
2017年 | 130篇 |
2016年 | 172篇 |
2015年 | 283篇 |
2014年 | 287篇 |
2013年 | 341篇 |
2012年 | 357篇 |
2011年 | 346篇 |
2010年 | 206篇 |
2009年 | 175篇 |
2008年 | 235篇 |
2007年 | 194篇 |
2006年 | 152篇 |
2005年 | 160篇 |
2004年 | 114篇 |
2003年 | 118篇 |
2002年 | 88篇 |
2001年 | 84篇 |
2000年 | 69篇 |
1999年 | 69篇 |
1998年 | 42篇 |
1997年 | 38篇 |
1996年 | 37篇 |
1995年 | 38篇 |
1994年 | 27篇 |
1993年 | 20篇 |
1992年 | 24篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有4728条查询结果,搜索用时 15 毫秒
141.
Objective
To develop person-centered episodes of care (PCE) for community-dwelling individuals in the top fifth percentile of Ontario health care expenditures in order to: (1) describe the main clinical groupings for spending; and (2) identify patterns of spending by health sector (e.g. acute care, home care, physician billings) within and across PCE.Data sources
Data were drawn from population-based administrative databases for all publicly funded health care in Ontario, Canada in 2010/11.Study design
This study is a retrospective cohort study.Data collection/extraction methods
A total of 587,982 community-dwelling individuals were identified among those accounting for the top 5% of provincial health care expenditures between April 1, 2010 and March 31, 2011. PCE were defined as starting with an acute care admission and persisting through subsequent care settings and providers until individuals were without health system contact for 30 days. PCE were classified according to the clinical grouping for the initial admission. PCE and non-PCE costs were calculated and compared to provide a comprehensive measurement of total health system costs for the year.Principal findings
Among this community cohort, 697,059 PCE accounted for nearly 70% ($11,815.3 million (CAD)) of total annual publicly-funded expenditures on high-cost community-dwelling individuals. The most common clinical groupings to start a PCE were Acute Planned Surgical (35.2%), Acute Unplanned Medical (21.0%) and Post-Admission Events (10.8%). Median PCE costs ranged from $3,865 (IQR = $1,712-$10,919) for Acute Planned Surgical to $20,687 ($12,207-$39,579) for Post-Admission Events. Inpatient acute ($8,194.5 million) and inpatient rehabilitation ($434.6 million) health sectors accounted for the largest proportions of allocated PCE spending over the year.Conclusions
Our study provides a novel methodological approach to categorize high-cost health system users into meaningful person-centered episodes. This approach helps to explain how costs are attributable within individuals across sectors and has applications in episode-based payment formulas and quality monitoring. 相似文献142.
Neethu Robinson Ali Danish Zaidi Mohit Rana Vinod A. Prasad Cuntai Guan Niels Birbaumer Ranganatha Sitaram 《PloS one》2016,11(7)
Recently, studies have reported the use of Near Infrared Spectroscopy (NIRS) for developing Brain–Computer Interface (BCI) by applying online pattern classification of brain states from subject-specific fNIRS signals. The purpose of the present study was to develop and test a real-time method for subject-specific and subject-independent classification of multi-channel fNIRS signals using support-vector machines (SVM), so as to determine its feasibility as an online neurofeedback system. Towards this goal, we used left versus right hand movement execution and movement imagery as study paradigms in a series of experiments. In the first two experiments, activations in the motor cortex during movement execution and movement imagery were used to develop subject-dependent models that obtained high classification accuracies thereby indicating the robustness of our classification method. In the third experiment, a generalized classifier-model was developed from the first two experimental data, which was then applied for subject-independent neurofeedback training. Application of this method in new participants showed mean classification accuracy of 63% for movement imagery tasks and 80% for movement execution tasks. These results, and their corresponding offline analysis reported in this study demonstrate that SVM based real-time subject-independent classification of fNIRS signals is feasible. This method has important applications in the field of hemodynamic BCIs, and neuro-rehabilitation where patients can be trained to learn spatio-temporal patterns of healthy brain activity. 相似文献
143.
144.
145.
146.
The plant‐specific CDKB1‐CYCB1 complex mediates homologous recombination repair in Arabidopsis 下载免费PDF全文
147.
148.
149.
Wenzhu Guo Tong Lian Baobao Wang Jiantao Guan Dong Yuan Huan Wang Fardous Mohammad Safiul Azam Xing Wan Weixuan Wang Qiuju Liang Haiyang Wang Jinxing Tu Chunyi Zhang Ling Jiang 《植物学报(英文版)》2019,61(6):675-690
As essential B vitamin for humans, folates accumulation in edible parts of crops, such as maize kernels, is of great importance for human health. But its breeding is always limited by the prohibitive cost of folate profiling. The molecular breeding is a more executable and efficient way for folate fortification, but is limited by the molecular knowledge of folate regulation. Here we report the genetic mapping of folate quantitative trait loci (QTLs) using a segregated population crossed by two maize lines, one high in folate (GEMS31) and the other low in folate (DAN3130). Two folate QTLs on chromosome 5 were obtained by the combination of F2 whole-exome sequencing and F3 kernel-folate profiling. These two QTLs had been confirmed by bulk segregant analysis using F6 pooled DNA and F7 kernel-folate profiling, and were overlapped with QTLs identified by another segregated population. These two QTLs contributed 41.6% of phenotypic variation of 5-formyltetrahydrofolate, the most abundant storage form among folate derivatives in dry maize grains, in the GEMS31×DAN3130 population. Their fine mapping and functional analysis will reveal details of folate metabolism, and provide a basis for marker-assisted breeding aimed at the enrichment of folates in maize kernels. 相似文献
150.
Jun Yin Xiaomin Guan Heng Zhang Longxiang Wang Hao Li Qing Zhang Tao Chen Zeyuan Xu Zonglie Hong Yangrong Cao Zhongming Zhang 《中国科学:生命科学英文版》2019,(9)
Symbiosis receptor-like kinase(SymRK) is a key protein mediating the legume-Rhizobium symbiosis. Our previous work has identified an MAP kinase kinase, SIP2, as a SymRK-interacting protein to positively regulate nodule organogenesis in Lotus japonicus, suggesting that an MAPK cascade might be involved in Rhizobium-legume symbiosis. In this study, LjMPK6 was identified as a phosphorylation target of SIP2. Stable transgenic L. japonicus with RNAi silencing of LjMPK6 decreased the numbers of nodule primordia(NP) and nodule, while plants overexpressing LjMPK6 increased the numbers of nodule, infection threads(ITs), and NP, indicating that LjMPK6 plays a positive role in nodulation. LjMPK6 could interact with a cytokinin receptor, LHK1 both in vivo and in vitro. LjMPK6 was shown to compete with LHP1 to bind to the receiver domain(RD) of LHK1 and to downregulate the expression of two LjACS(1-aminocyclopropane-1-carboxylic acid synthase) genes and ethylene levels during nodulation. This study demonstrated an important role of LjMPK6 in regulation of nodule organogenesis and ethylene production in L. japonicus. 相似文献