全文获取类型
收费全文 | 7860篇 |
免费 | 426篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 81篇 |
儿科学 | 171篇 |
妇产科学 | 199篇 |
基础医学 | 1208篇 |
口腔科学 | 159篇 |
临床医学 | 804篇 |
内科学 | 1551篇 |
皮肤病学 | 88篇 |
神经病学 | 550篇 |
特种医学 | 755篇 |
外国民族医学 | 2篇 |
外科学 | 990篇 |
综合类 | 37篇 |
一般理论 | 1篇 |
预防医学 | 433篇 |
眼科学 | 81篇 |
药学 | 512篇 |
中国医学 | 7篇 |
肿瘤学 | 694篇 |
出版年
2021年 | 122篇 |
2020年 | 63篇 |
2019年 | 108篇 |
2018年 | 127篇 |
2017年 | 90篇 |
2016年 | 116篇 |
2015年 | 133篇 |
2014年 | 198篇 |
2013年 | 240篇 |
2012年 | 407篇 |
2011年 | 350篇 |
2010年 | 190篇 |
2009年 | 209篇 |
2008年 | 350篇 |
2007年 | 368篇 |
2006年 | 389篇 |
2005年 | 357篇 |
2004年 | 339篇 |
2003年 | 324篇 |
2002年 | 328篇 |
2001年 | 354篇 |
2000年 | 334篇 |
1999年 | 243篇 |
1998年 | 89篇 |
1997年 | 90篇 |
1996年 | 56篇 |
1995年 | 53篇 |
1993年 | 43篇 |
1992年 | 130篇 |
1991年 | 149篇 |
1990年 | 126篇 |
1989年 | 151篇 |
1988年 | 121篇 |
1987年 | 117篇 |
1986年 | 97篇 |
1985年 | 106篇 |
1984年 | 75篇 |
1983年 | 62篇 |
1982年 | 42篇 |
1980年 | 38篇 |
1979年 | 89篇 |
1978年 | 49篇 |
1977年 | 45篇 |
1976年 | 49篇 |
1975年 | 45篇 |
1974年 | 67篇 |
1973年 | 61篇 |
1972年 | 55篇 |
1970年 | 54篇 |
1969年 | 42篇 |
排序方式: 共有8323条查询结果,搜索用时 15 毫秒
1.
Josh Greenstein Devjani Das Josie Acuna Monica Kapoor Cara Brown Abbas Husain Brendan Lally Barry Hahn 《The American journal of emergency medicine》2019,37(2):313-316
Background
In the emergency department, rib fractures are a common finding in patients who sustain chest trauma. Rib fractures may be a sign of significant, underlying pathology, especially in the elderly patients where rib fractures are associated with significant morbidity and mortality. To date, no studies have evaluated the ability of ultrasound to detect rib fractures using cadaver models and subsequently use this model as a teaching tool.Objectives
The purpose of this study was to determine if it is possible to generate rib fractures on cadaver models which could be accurately identified using ultrasound.Methods
This was a cross-sectional study performed during one session at a cadaver lab. A single hemithorax from four adult cadavers were used as models. Single rib fractures on each of rib five through eight were created. Four subjects, blinded to the normal versus fractured ribs, were asked to identify the presence of a fracture on each rib.Results
A total of 8 of 16 potential ribs had fractured induced by study staff. Mean accuracy was 55% for all subjects. The overall sensitivity and specificity for detecting rib fractures was 50% (CI: 31.89–68.11) and 59.38% (CI: 35.69–73.55) respectively. The overall PPV and NPV was 55.17% and 54.29% respectively.Conclusions
In this pilot study, subjects were not able to detect induced rib fractures using ultrasound on cadaver models. The use of this model as a teaching tool in the detection of rib fractures requires further investigation. 相似文献2.
3.
Xin Zhang Tim Zegar Tim Weiser Feda H. Hamdan Benedict-Tilman Berger Romain Lucas Dimitrios-IIias Balourdas Swetlana Ladigan Phyllis F. Cheung Sven-Thorsten Liffers Marija Trajkovic-Arsic Bjoern Scheffler Andreas C. Joerger Stephan A. Hahn Steven A. Johnsen Stefan Knapp Jens T. Siveke 《International journal of cancer. Journal international du cancer》2020,147(10):2847-2861
4.
Ronny Redlich Ilona Schneider Nicole Kerkenberg Nils Opel Jonas Bauhaus Verena Enneking Jonathan Repple Elisabeth J. Leehr Dominik Grotegerd Claas Khler Katharina Frster Katharina Dohm Susanne Meinert Tim Hahn Harald Kugel Kathrin Schwarte Christiane Schettler Katharina Domschke Volker Arolt Walter Heindel Bernhard T. Baune Weiqi Zhang Christa Hohoff Udo Dannlowski 《Human brain mapping》2020,41(3):594-604
Epigenetic alterations of the brain‐derived neurotrophic factor (BDNF) gene have been associated with psychiatric disorders in humans and with differences in amygdala BDNF mRNA levels in rodents. This human study aimed to investigate the relationship between the functional BDNF‐Val66Met polymorphism, its surrounding DNA methylation in BDNF exon IX, amygdala reactivity to emotional faces, and personality traits. Healthy controls (HC, n = 189) underwent functional MRI during an emotional face‐matching task. Harm avoidance, novelty seeking and reward dependence were measured using the Tridimensional Personality Questionnaire (TPQ). Individual BDNF methylation profiles were ascertained and associated with several BDNF single nucleotide polymorphisms surrounding the BDNF‐Val66Met, amygdala reactivity, novelty seeking and harm avoidance. Higher BDNF methylation was associated with higher amygdala reactivity (x = 34, y = 0, z = ?26, t(166) = 3.00, TFCE = 42.39, p(FWE) = .045), whereby the BDNF‐Val66Met genotype per se did not show any significant association with brain function. Furthermore, novelty seeking was negatively associated with BDNF methylation (r = ?.19, p = .015) and amygdala reactivity (r = ?.17, p = .028), while harm avoidance showed a trend for a positive association with BDNF methylation (r = .14, p = .066). The study provides first insights into the relationship among BDNF methylation, BDNF genotype, amygdala reactivity and personality traits in humans, highlighting the multidimensional relations among genetics, epigenetics, and neuronal functions. The present study suggests a possible involvement of epigenetic BDNF modifications in psychiatric disorders and related brain functions, whereby high BDNF methylation might reduce BDNF mRNA expression and upregulate amygdala reactivity. 相似文献
5.
Beate Grass Blondel Crosdale Matthew Keyzers Poorva Deshpande Cecil Hahn Linh G Ly Patrick J McNamara 《Paediatrics & child health》2020,25(8):511
AimTo investigate the implementation of amplitude-integrated electroencephalography (aEEG) as bedside monitoring tool of cerebral function in tertiary Canadian Neonatal Intensive Care Units (NICU) over the past decade.MethodsLongitudinal study consisting of online surveys of neonatologists on the use of aEEG in 2009 and 2018.ResultsThe response rate to the survey was 72 of 149 (49%) in 2009 and 18 of 30 (60%) in 2018, respectively. aEEG has been implemented in almost all (2009: 62.5%; 2018: 94%) tertiary Canadian NICUs. Two-thirds (2009: 67%; 2018: 71%) of the respondents considered information from aEEG tracing helpful in clinical practice. The main indications for aEEG were term neonates with hypoxic ischemic encephalopathy (2009 and 2018: 76%) and seizure detection/surveillance (2009: 88%; 2018: 94%). Teaching on aEEG has been implemented for neonatologists (2018: 100%) and health care providers (2018: 50%) in tertiary Canadian NICUs but there is a lack of standardization of training. Use of aEEG in preterm neonates (2009: 37%, 2018: 33%) and application of aEEG in research (18% reported occasional use) is less common.ConclusionaEEG is well established in tertiary Canadian NICUs to monitor cerebral function and detect seizure activity. There is a need to develop formalized aEEG training programs and methods to assess competence. Further implementation of aEEG in preterm neonates and research is desirable. 相似文献
6.
Amanda C. Hahn Claire I. Fisher Lisa M. DeBruine Benedict C. Jones 《Archives of sexual behavior》2016,45(4):871-875
Studies of the sex-specificity of sexual arousal in adults (i.e., the tendency to respond more strongly to preferred-sex individuals than non-preferred sex individuals) have suggested that heterosexual men, homosexual men, and homosexual women show stronger sex-specific responses than do heterosexual women. Evidence for a similar pattern of results in studies investigating the reward value of faces is equivocal. Consequently, we investigated the effects of (1) sexual orientation (homosexual vs. heterosexual), (2) sex (male vs. female), (3) image sex (preferred-sex vs. non-preferred-sex), and (4) the physical attractiveness of the individual shown in the image on the reward value of faces. Participants were 130 heterosexual men, 130 homosexual men, 130 heterosexual women, and 130 homosexual women. The reward value of faces was assessed using a standard key-press task. Multilevel modeling of responses indicated that images of preferred-sex individuals were more rewarding than images of non-preferred-sex individuals and that this preferred-sex bias was particularly pronounced when more physically attractive faces were presented. These effects were not qualified by interactions involving either the sexual orientation or the sex of our participants, however, suggesting that the preferred-sex bias in the reward value of faces is similar in heterosexual men, homosexual men, heterosexual women, and homosexual women. 相似文献
7.
Minwoo Shin Seok Hahn Jisook Yi Yun-Jung Lim Jin-Young Bang 《Ultrasound in medicine & biology》2019,45(1):246-254
The aim of this study was to evaluate the diagnostic potential of real-time sonoelastography (RSE) in medial epicondylitis by comparing clinically diagnosed patients and patients without medial elbow pain. From July 2016 to December 2017, gray-scale sonographic findings (swelling, cortical irregularity, hypo-echogenicity, calcification and tear), color Doppler findings (hyperemia) and sonoelastographic findings (elastographic grade on a 3-point visual scale and strain ratio from two regions of interest) for 63 elbows of 56 patients were compared. Twenty-four patients with 29 imaged elbows were clinically diagnosed with medial epicondylitis, and 32 patients with 34 imaged elbows had no medial elbow pain. Cortical irregularity, hypo-echogenicity, calcification, elastographic grade and strain ratio revealed significant differences (p < 0.05). Among these, strain ratio had the highest diagnostic performance (area under the curve: 0.985). Real-time sonoelastography, which can obtain both elastographic grade and strain ratio, is valuable as a supplementary tool in the diagnosis of medial epicondylitis. 相似文献
8.
Won-ho Hahn Jaehan Kim Seunghyun Song Suyeon Park 《The journal of maternal-fetal & neonatal medicine》2019,32(6):985-991
Objectives: Human milk oligosaccharides (HMOs) are known as important factors in neurologic and immunologic development of neonates. Moreover, freeze-drying seems to be a promising storage method to improve the processes of human milk banks. However, the effects of pasteurization and freeze-drying on HMOs were not evaluated yet. The purpose of this study is to analyze and compare the HMOs profiles of human milk collected before and after the pasteurization and freeze-drying.Methods: Totally nine fresh human milk samples were collected from three healthy mothers at the first, second, and third week after delivery. The samples were treated with Holder pasteurization and freeze-drying. HMOs profiles were analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight/time-of-flight (TOF/TOF) mass spectrometry and compared between samples collected before and after the treatments.Results: Human milk samples showed significantly different HMO patterns between mothers. However, HMOs were not affected by lactation periods within 3 weeks after delivery (r2?=?0.972–0.999, p?.001). Moreover, both of pasteurization and freeze-drying were found not to affect HMO patterns in a correlation analysis (r2?=?0.989–0.999, p?.001).Conclusion: HMO patterns were found not to be affected by pasteurization and freeze-drying of donor milks. We hope that introducing freeze-drying to the human milk banks would be encouraged by the present study. However, the storage length without composition changes of HMOs after freeze-drying needs to be evaluated in the further studies. 相似文献
9.
Apoorva Sikka Hamidreza Jamalabadi Marina Krylova Sarah Alizadeh Johan N. van der Meer Lena Danyeli Matthias Deliano Petya Vicheva Tim Hahn Thomas Koenig Deepti R. Bathula Martin Walter 《Human brain mapping》2020,41(9):2334-2346
Electroencephalogram (EEG) microstates that represent quasi‐stable, global neuronal activity are considered as the building blocks of brain dynamics. Therefore, the analysis of microstate sequences is a promising approach to understand fast brain dynamics that underlie various mental processes. Recent studies suggest that EEG microstate sequences are non‐Markovian and nonstationary, highlighting the importance of the sequential flow of information between different brain states. These findings inspired us to model these sequences using Recurrent Neural Networks (RNNs) consisting of long‐short‐term‐memory (LSTM) units to capture the complex temporal dependencies. Using an LSTM‐based auto encoder framework and different encoding schemes, we modeled the microstate sequences at multiple time scales (200–2,000 ms) aiming to capture stably recurring microstate patterns within and across subjects. We show that RNNs can learn underlying microstate patterns with high accuracy and that the microstate trajectories are subject invariant at shorter time scales (≤400 ms) and reproducible across sessions. Significant drop in the reconstruction accuracy was observed for longer sequence lengths of 2,000 ms. These findings indirectly corroborate earlier studies which indicated that EEG microstate sequences exhibit long‐range dependencies with finite memory content. Furthermore, we find that the latent representations learned by the RNNs are sensitive to external stimulation such as stress while the conventional univariate microstate measures (e.g., occurrence, mean duration, etc.) fail to capture such changes in brain dynamics. While RNNs cannot be configured to identify the specific discriminating patterns, they have the potential for learning the underlying temporal dynamics and are sensitive to sequence aberrations characterized by changes in metal processes. Empowered with the macroscopic understanding of the temporal dynamics that extends beyond short‐term interactions, RNNs offer a reliable alternative for exploring system level brain dynamics using EEG microstate sequences. 相似文献
10.