全文获取类型
收费全文 | 3080篇 |
免费 | 221篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 38篇 |
儿科学 | 83篇 |
妇产科学 | 68篇 |
基础医学 | 423篇 |
口腔科学 | 54篇 |
临床医学 | 306篇 |
内科学 | 616篇 |
皮肤病学 | 74篇 |
神经病学 | 349篇 |
特种医学 | 52篇 |
外科学 | 359篇 |
综合类 | 19篇 |
预防医学 | 394篇 |
眼科学 | 77篇 |
药学 | 196篇 |
中国医学 | 15篇 |
肿瘤学 | 186篇 |
出版年
2024年 | 11篇 |
2023年 | 76篇 |
2022年 | 117篇 |
2021年 | 228篇 |
2020年 | 140篇 |
2019年 | 148篇 |
2018年 | 177篇 |
2017年 | 103篇 |
2016年 | 105篇 |
2015年 | 97篇 |
2014年 | 139篇 |
2013年 | 168篇 |
2012年 | 235篇 |
2011年 | 247篇 |
2010年 | 145篇 |
2009年 | 113篇 |
2008年 | 157篇 |
2007年 | 149篇 |
2006年 | 134篇 |
2005年 | 126篇 |
2004年 | 123篇 |
2003年 | 89篇 |
2002年 | 69篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 16篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 14篇 |
1994年 | 3篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1937年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有3309条查询结果,搜索用时 15 毫秒
81.
From the Cover: COVID-19 lockdown induces disease-mitigating structural changes in mobility networks
Frank Schlosser Benjamin F. Maier Olivia Jack David Hinrichs Adrian Zachariae Dirk Brockmann 《Proceedings of the National Academy of Sciences of the United States of America》2020,117(52):32883
In the wake of the COVID-19 pandemic many countries implemented containment measures to reduce disease transmission. Studies using digital data sources show that the mobility of individuals was effectively reduced in multiple countries. However, it remains unclear whether these reductions caused deeper structural changes in mobility networks and how such changes may affect dynamic processes on the network. Here we use movement data of mobile phone users to show that mobility in Germany has not only been reduced considerably: Lockdown measures caused substantial and long-lasting structural changes in the mobility network. We find that long-distance travel was reduced disproportionately strongly. The trimming of long-range network connectivity leads to a more local, clustered network and a moderation of the “small-world” effect. We demonstrate that these structural changes have a considerable effect on epidemic spreading processes by “flattening” the epidemic curve and delaying the spread to geographically distant regions.During the first phase of the coronavirus disease 2019 (COVID-19) pandemic, countries around the world implemented a host of containment policies aimed at mitigating the spread of the disease (1–4). Many policies restricted human mobility, intending to reduce close-proximity contacts, the major driver of the disease’s spread (5). In Germany, these policies included border closures, travel bans, and restrictions of public activity (school and business closures), paired with appeals by the government to avoid trips voluntarily whenever possible (6). We refer to these policies as “lockdown” measures for brevity.Based on various digital data sources such as mobile phone data or social media data, several studies show that mobility significantly changed during lockdowns (7). Most studies focused on general mobility trends and confirmed an overall reduction in mobility in various countries (8–12). Other research focused on the relation between mobility and disease transmission: For instance, it has been argued that mobility reduction is likely instrumental in reducing the effective reproduction number in many countries (13–17), in agreement with theoretical models and simulations, which have shown that containment can effectively slow down disease transmission (18–20).However, it remains an open question whether the mobility restrictions promoted deeper structural changes in mobility networks and how these changes impact epidemic spreading mediated by these networks. Recently, Galeazzi et al. (21) found increased geographical fragmentation of the mobility network. A thorough understanding of how structural mobility network changes impact epidemic spreading is needed to correctly assess the consequences of mobility restrictions not only for the current COVID-19 pandemic, but also for similar scenarios in the future.Here, we analyze structural changes in mobility patterns in Germany during the COVID-19 pandemic. We analyze movements recorded from mobile phones of 43.6 million individuals in Germany. Beyond a general reduction in mobility, we find considerable structural changes in the mobility network. Due to the reduction of long-distance travel, the network becomes more local and lattice-like. Most importantly, we find a changed scaling relation between path lengths and geographic distance: During lockdown, the effective distance (and arrival time in spreading processes) to a destination continually grows with geographic distance. This shows a marked reduction of the “small-world” characteristic, where geographic distance is usually of lesser importance in determining path lengths (22, 23). Using simulations of a commuter-based susceptible-infected-removed (SIR) model, we demonstrate that these changes have considerable practical implications as they suppress (or “flatten”) the curve of an epidemic remarkably and delay the disease’s arrival between distant regions. 相似文献
82.
83.
Nørgaard BL Terkelsen CJ Riiskjaer M Holmvang L Grip L Heickendorff L Thygesen K 《Acute cardiac care》2008,10(3):159-166
There is limited information about the in-hospital plasma profile of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with non-ST-elevation acute coronary syndrome (NSTACS) and furthermore, the prognostic influence of the timing of NT-proBNP measurements in NSTACS is unsettled. These subject matters are elucidated in this study composed of 455 patients with NSTACS (symptoms <24 h). NT-proBNP was measured at 0, 6, 12, 24, 36, 48, 72 and 96 h following admission. Any death was registered at follow-up (median: 2.3 years). The study demonstrated a monophasic profile of the plasma NT-proBNP values, reaching a maximum at 6 hours, and it showed an independent prognostic significance of NT-proBNP irrespective of the sampling time. Risk prediction by NT-proBNP was improved by combining the baseline measurement and one value taken between 24 and 96 h (at 48 h, P<0.001). No additional prognostic information was provided by including more than one late in-hospital NT-proBNP value. Conclusions: The in-hospital NT-proBNP measurements exhibit a monophasic profile in patients with NSTACS and these values provide independent prognostic information as regards mortality irrespective of the sampling time. Moreover, risk prediction of NT-proBNP is strengthened by combining the admission measurement with an additional value during the hospitalization. 相似文献
84.
85.
86.
87.
DM Molina OC Finney M Arevalo-Herrera S Herrera PL Felgner MJ Gardner X Liang R Wang 《The American journal of tropical medicine and hygiene》2012,87(3):460-469
Abstract. The development of pre-erythrocytic Plasmodium vivax vaccines is hindered by the lack of in vitro culture systems or experimental rodent models. To help bypass these roadblocks, we exploited the fact that naturally exposed Fy- individuals who lack the Duffy blood antigen (Fy) receptor are less likely to develop blood-stage infections; therefore, they preferentially develop immune responses to pre-erythrocytic-stage parasites, whereas Fy+ individuals experience both liver- and blood-stage infections and develop immune responses to both pre-erythrocytic and erythrocytic parasites. We screened 60 endemic sera from P. vivax-exposed Fy+ or Fy- donors against a protein microarray containing 91 P. vivax proteins with P. falciparum orthologs that were up-regulated in sporozoites. Antibodies against 10 P. vivax antigens were identified in sera from P. vivax-exposed individuals but not unexposed controls. This technology has promising implications in the discovery of potential vaccine candidates against P. vivax malaria. 相似文献
88.
Berti-Couto Sde A Couto-Souza PH Jacobs R Nackaerts O Rubira-Bullen IR Westphalen FH Moysés SJ Ignácio SA Costa MB Tolazzi AL 《Journal of applied oral science : revista FOB》2012,20(2):157-161
Objective
The aim of this study was to evaluate the effectiveness of clinical criteria for the diagnosis of hyposalivation in hospitalized patients.Material and Methods
A clinical study was carried out on 145 subjects (48 males; 97 females; aged 20 to 90 years). Each subject was clinically examined, in the morning and in the afternoon, along 1 day. A focused anamnesis allowed identifying symptoms of hyposalivation, like xerostomia complaints (considered as a reference symptom), chewing difficulty, dysphagia and increased frequency of liquid intake. Afterwards, dryness of the mucosa of the cheecks and floor of the mouth, as well as salivary secretion during parotid gland stimulation were assessed during oral examination.Results
Results obtained with Chi-square tests showed that 71 patients (48.9%) presented xerostomia complaints, with a significant correlation with all hyposalivation symptoms (p<0.05). Furthermore, xerostomia was also significantly correlated with all data obtained during oral examination in both periods of evaluation (p<0.05).Conclusion
Clinical diagnosis of hyposalivation in hospitalized patients is feasible and can provide an immediate and appropriate therapy avoiding further problems and improving their quality of life. 相似文献89.
90.
Christina R Maxwell Julia Parish-Morris Olivia Hsin Jennifer C Bush Robert T Schultz 《Journal of Neurodevelopmental Disorders》2013,5(1):25