收费全文 | 3457773篇 |
免费 | 272944篇 |
国内免费 | 6123篇 |
耳鼻咽喉 | 50080篇 |
儿科学 | 110741篇 |
妇产科学 | 95257篇 |
基础医学 | 487590篇 |
口腔科学 | 102398篇 |
临床医学 | 314203篇 |
内科学 | 667933篇 |
皮肤病学 | 72888篇 |
神经病学 | 289203篇 |
特种医学 | 137736篇 |
外国民族医学 | 1247篇 |
外科学 | 519279篇 |
综合类 | 83354篇 |
现状与发展 | 4篇 |
一般理论 | 1459篇 |
预防医学 | 277346篇 |
眼科学 | 81846篇 |
药学 | 258293篇 |
7篇 | |
中国医学 | 6382篇 |
肿瘤学 | 179594篇 |
2018年 | 35550篇 |
2016年 | 30994篇 |
2015年 | 34802篇 |
2014年 | 48738篇 |
2013年 | 75329篇 |
2012年 | 100925篇 |
2011年 | 107077篇 |
2010年 | 63042篇 |
2009年 | 59362篇 |
2008年 | 102146篇 |
2007年 | 108151篇 |
2006年 | 109160篇 |
2005年 | 106234篇 |
2004年 | 102931篇 |
2003年 | 99251篇 |
2002年 | 97895篇 |
2001年 | 155868篇 |
2000年 | 162012篇 |
1999年 | 136688篇 |
1998年 | 39898篇 |
1997年 | 36082篇 |
1996年 | 35470篇 |
1995年 | 34374篇 |
1994年 | 32346篇 |
1993年 | 30250篇 |
1992年 | 110078篇 |
1991年 | 106395篇 |
1990年 | 103263篇 |
1989年 | 99793篇 |
1988年 | 92732篇 |
1987年 | 91541篇 |
1986年 | 86886篇 |
1985年 | 83465篇 |
1984年 | 63419篇 |
1983年 | 54396篇 |
1982年 | 33026篇 |
1981年 | 29502篇 |
1980年 | 27836篇 |
1979年 | 60149篇 |
1978年 | 42374篇 |
1977年 | 35823篇 |
1976年 | 33555篇 |
1975年 | 35532篇 |
1974年 | 43746篇 |
1973年 | 41742篇 |
1972年 | 38865篇 |
1971年 | 36200篇 |
1970年 | 33812篇 |
1969年 | 31579篇 |
1968年 | 28818篇 |
Introduction
The aim of this study was to evaluate the root canal shaping effect of instruments manufactured from nickel titanium, M-Wire, and Gold wire with different glide path preparation techniques.Methods
One hundred thirty-five mesiobuccal canals of extracted human maxillary molars were randomly divided into 3 equal groups (N = 45) for glide path preparation with K-files (KF) (Dentsply Sirona, Ballaigues, Switzerland), One G (OG) files (Micro-Mega, Besançon, France), and ProGlider (PG) files (Dentsply Sirona). Specimens of each glide path group were further divided equally into 3 groups for instrumentation with ProTaper Next (PTN, Dentsply Sirona), One Shape (OS, Micro-Mega), and WaveOne Gold (WOG, Dentsply Sirona) systems (n = 15). Micro–computed tomographic imaging was used to scan teeth before instrumentation and after shaping to compare centering ratio and canal transportation values at the apical, midroot, and coronal levels and the overall changes in canal volume. Data sets were statistically analyzed (analysis of variance and Kruskal-Wallis H tests).Results
The centering ratios for all groups were statistically similar at all levels. Apical canal transportation was significantly high for K/OS and K/PTN (P = .003). Midroot canal transportation was significantly high for K/PTN, K/OS, and OG/OS (P = .0003). Coronal canal transportation was significantly high for K/PTN and K/OS (P = .011). The highest change in canal volume was observed with all PTN groups and the lowest with PG/WOG (P = .06).Conclusions
WOG manufactured from Gold wire combined with PG showed better root canal shaping ability and removed less dentin from the canal walls. The nickel-titanium (OS) and M-Wire (PTN) instruments used in combination with KF significantly transported more canals. PTN removed the most dentin from the canal walls regardless of the GPP technique. 相似文献Background and Aims
Diet is known to play a decisive role in the development of coronary heart disease (CHD). One factor believed to decrease lifetime risk of CHD is the consumption of omega-3 fatty acids. Yet, conclusive evidence regarding the potential cardioprotective effects of fatty acids is far from being reached. The present study aimed to provide further evidence on the association of serum fatty acid profiles with CHD risk.Methods and Results
The CARdio-vascular Disease, Living and Ageing in Halle study (CARLA study) is an observational cohort study comprising an older adult's general population with a high level of cardiovascular risk factors. In a matched case–control design the serum fatty acid concentrations of 73 subjects with an incident fatal or nonfatal CHD event were compared to 146 controls matched for sex and age. Our data show that the participants of the CARLA study are underserved in unsaturated fatty acids with respect to current dietary recommendations. In addition, the ratio of omega-6 to omega-3 fatty acids was determined to be 8:1 which underlines the consumption of a Western-style diet enriched in omega-6 fatty acids. There were no significant differences in fatty acid patterns between cases and controls. Thus, no clear association of particular serum fatty acid levels with cardiovascular risk was found.Conclusion
Our results support the conclusion that in populations with a homogenous low level of omega-3 polyunsaturated fatty acids consumption, serum fatty acid levels are not associated with CHD risk. 相似文献Background
Total knee arthroplasty is a treatment option for debilitating arthritis. In the postoperative period, patients experience moderate to severe pain affecting the rehabilitation, hospital stay, and patient satisfaction. This study aims at utilizing current best evidence to determine whether adductor canal block (ACB) or periarticular injection (PAI) is a better modality for managing short-term postoperative pain and opioid consumption.Methods
Embase, MEDLINE, HealthStar, Emcare, and PubMed were searched for randomized controlled trials from 1946 to August 2018, for literature addressing the comparison of ACB and PAI for pain management in the setting of total knee arthroplasty. A systematic review and meta-analysis were performed.Results
Six studies were included in our meta-analysis. When examining the combined visual analog scale (VAS) pain values for each group, analysis demonstrated greater reduction in scores for the PAI group, and the difference was statistically significant (P = .001). When comparing the VAS scores of subgroups analyzed at specific periods in time, there was a trend toward lower VAS scores in subgroups analyzed at 24 hours and 48 hours postoperatively (at rest and at movement) in the PAI group. Overall opioid consumption was lower in the PAI group, with demonstrated statistical significance (P = .03). When comparing the postoperative subgroups, there was a trend toward decreased opioid use in the PAI group, with 13.25% less opioid use at 48 hours and 9.5% less opioid use at 24 hours.Conclusion
PAI could significantly improve postoperative pain and opioid consumption when compared with ACB. Additional, high-quality studies are required to further address this topic. 相似文献Background and aim
The associations of long-term exposure to particulate matter <10 μm in size (PM10), nitrogen dioxide (NO2), carbon monoxide (CO), sulfur dioxide (SO2), and ozone (O3) with cardiometabolic diseases (CMD) remain uncertain in the Korean population. Therefore, we sought to examine the associations between PM10, NO2, CO, SO2, and O3 and CMD using data collected from the Korean Community Health Survey.Methods and results
We selected 100,867 adults aged 19 years or older who had lived in the same domicile for ≥10 years and surveyed them to collect data on socioeconomic characteristics; health-related behaviors; obesity; and physician-diagnosed CMD history, including hypertension, diabetes mellitus, dyslipidemia, stroke, myocardial infarction, and ischemic heart disease. We calculated interquartile ranges for PM10, NO2, CO, SO2, and O3 from the 10 year average concentrations (2003–2012). Hypertension, diabetes mellitus, and dyslipidemia were positively associated with PM10, NO2, CO, SO2, and O3 after adjusting for confounding factors. Obesity was positively associated with PM10, NO2, SO2, and O3. On the other hand, we found no associations between stroke, myocardial infarction, and ischemic heart disease and exposure to PM10, NO2, CO, SO2, and O3 in these subjects. In subjects aged ≥65 years, the risk of dyslipidemia was markedly increased under exposure to NO2 and CO compared to subjects aged <65 years. The risk of obesity was also significantly increased under exposure to PM10 and NO2. However, sex differences in these associations were not found.Conclusion
Long-term exposure to PM10, NO2, CO, SO2, and O3 may be a risk factor of CMD in Korean adults. 相似文献Introduction
Physician communication impacts patient outcomes. However, communication skills, especially around difficult conversations, remain suboptimal, and there is no clear way to determine the validity of entrustment decisions. The aims of this study were to 1) describe the development of a simulation-based mastery learning (SBML) curriculum for breaking bad news (BBN) conversation skills and 2) set a defensible minimum passing standard (MPS) to ensure uniform skill acquisition among learners.Innovation
An SBML BBN curriculum was developed for fourth-year medical students. An assessment tool was created to evaluate the acquisition of skills involved in a BBN conversation. Pilot testing was completed to confirm improvement in skill acquisition and set the MPS.Outcomes
A BBN assessment tool containing a 15-item checklist and six scaled items was developed. Students' checklist performance improved significantly at post-test compared to baseline (mean 65.33%, SD = 12.09% vs mean 88.67%, SD = 9.45%, P < 0.001). Students were also significantly more likely to have at least a score of 4 (on a five-point scale) for the six scaled questions at post-test. The MPS was set at 80%, requiring a score of 12 items on the checklist and at least 4 of 5 for each scaled item. Using the MPS, 30% of students would require additional training after post-testing.Comments
We developed a SBML curriculum with a comprehensive assessment of BBN skills and a defensible competency standard. Future efforts will expand the mastery model to larger cohorts and assess the impact of rigorous education on patient care outcomes. 相似文献Introduction
In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.Methods
We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.Results
A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.Conclusion
The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department. 相似文献Background
Atypical hemolytic uremic syndrome (aHUS) is a complement-mediated disease manifesting in thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury. It has a higher incidence of extrarenal manifestations, including central nervous system findings like seizure or stroke, pancreatitis, and cardiac manifestations.Case Report
We present a case of an unimmunized 14-month-old girl presenting with generalized seizure and ultimately diagnosed with aHUS.Why Should an Emergency Physician Be Aware of This?
These atypical neurological symptoms can cause the diagnosis to be commonly missed in the emergency department. The etiology of approximately 60% of patients with aHUS can be attributed to genetic mutations in complement regulators including factor H, membrane cofactor protein, factor I, activator factor B, or C3. Although previously treated with plasma transfusion and immunosuppressants, eculizumab is a newer treatment that has been changing prognosis and management of aHUS, but it should be administered within 48 h of symptom onset for best efficacy. 相似文献Materials and methods: Two neuropsychological tests, one subjective straight-ahead pointing (SSA) test and one wheelchair navigation test were carried out before the combination protocol, immediately after, 1?h later, and 24?h later.
Results: The results showed a reduction of neglect spatial bias following the protocol lasted at least 24?h in all the tests (except for the SSA test due to the unavailability of the pointing device).
Conclusions: The range of improvements in the symptoms of spatial neglect suggests that this therapeutic intervention based on the combining neck-muscle vibration to voluntary arm movements could be a useful treatment for this condition. One of future investigation axes should be the development of a vibratory tool in order to facilitate the combining this proprioceptive stimulation to daily activities.
- Implications for rehabilitation
Spatial neglect is a perplexing neuropsychological syndrome, affecting different domains of spatial cognition and impacting also the functional domain.
The treatments based on neck-muscle vibration are simple to use, non-invasive and requires none active participation of patient.
A therapeutic intervention based on the combining left neck-muscle vibration and voluntary arm movements in a left-spatial-neglect show a lasting reduction of symptoms especially in daily activities.
The combination of treatments based on the Bottom–Up approach opens innovative perspectives in rehabilitation.