首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1307篇
  免费   76篇
  国内免费   8篇
耳鼻咽喉   6篇
儿科学   21篇
妇产科学   56篇
基础医学   98篇
口腔科学   19篇
临床医学   127篇
内科学   274篇
皮肤病学   12篇
神经病学   38篇
特种医学   179篇
外科学   183篇
综合类   32篇
一般理论   1篇
预防医学   101篇
眼科学   55篇
药学   108篇
中国医学   2篇
肿瘤学   79篇
  2023年   8篇
  2022年   18篇
  2021年   43篇
  2020年   28篇
  2019年   37篇
  2018年   56篇
  2017年   38篇
  2016年   38篇
  2015年   48篇
  2014年   69篇
  2013年   83篇
  2012年   104篇
  2011年   131篇
  2010年   72篇
  2009年   60篇
  2008年   90篇
  2007年   83篇
  2006年   77篇
  2005年   74篇
  2004年   51篇
  2003年   38篇
  2002年   51篇
  2001年   15篇
  2000年   5篇
  1999年   6篇
  1998年   7篇
  1997年   6篇
  1996年   4篇
  1995年   4篇
  1994年   2篇
  1993年   4篇
  1992年   2篇
  1991年   6篇
  1990年   3篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   2篇
  1984年   6篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1970年   2篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1965年   1篇
  1958年   1篇
排序方式: 共有1391条查询结果,搜索用时 843 毫秒
991.
The American Society of Emergency Radiology (ASER) was founded in 1988 and is celebrating its 25th Anniversary. ASER is thriving and emergency radiology has never enjoyed greater popularity than at present. This history describes the genesis of the Society, its growth and current state of affairs. It is based on the recollections and personal files of the authors, one Founder and both former ASER Presidents and Gold Medalists, the ASER archives, and interviews and correspondence with many ASER members. It is hoped that this brief review will be interesting to the reader, provide some insight into ASER evolution over the years, and hold some lessons moving forward.  相似文献   
992.
An improved loop mediated isothermal amplification (LAMP) assay for rapid, sensitive and specific detection of cyprinid herpes virus-3 (CyHV-3), also known as koi herpes virus (KHV), was developed. The lower detection limit of the CyHV-3-LAMP assay is 10 fg DNA which equivalent to 30 copies of CyHV-3 genome. Nucleic acid lateral flow assay was used for visual detection of the LAMP products. The LAMP- nucleic acid lateral flow assay relies on DNA hybridization technology and antigen–antibody reactions in combination with LAMP. For application of this assay, the biotinylated LAMP product was hybridized with a FITC-labelled specific probe for 5 min. The resulting DNA complex could be visualised as purple band at the strip test line within 5 min of sample exposure. The nucleic acid lateral flow analysis of the LAMP product was equivalent in sensitivity but more rapid than the conventional agarose gel electrophoresis. The combination of LAMP assay with the nucleic acid lateral flow analysis can simplify the diagnosis and screening of CyHV-3 as it is simple, requires very little training, does not require specialized equipment such as a thermal cycler, the results are read visually with no need to run a gel and has a high sensitivity and specificity.  相似文献   
993.
994.
Proper interpretation of the spectral Doppler signal and elucidation of the underlying hemodynamics can at times be problematic due to confounding factors, one of them being a rapid heart rate. In this article, we discuss the use of carotid sinus massage (CSM) in the echocardiography laboratory as a maneuver to reduce the resting heart rate and thus render the transmitral Doppler signal more amenable to analysis. We provide examples of the value of the CSM in the assessment of left ventricular filling pressure.  相似文献   
995.
The aim of this study was to quantify the response of the myocardial transverse relaxation times (ΔT2*) to hyperoxic respiratory challenge (HRC) at different field strengths in an intra‐individual comparison of healthy volunteers and in a patient with coronary artery disease. Blood oxygenation level‐dependent (BOLD) cardiovascular MR (CMR) data were acquired in 10 healthy volunteers (five women, five men; mean age, 29 ± 3 years; range, 22–35 years) at 1.5 and 3.0 T. Medical air (21% O2), pure oxygen and carbogen (95% O2, 5% CO2) were administered in a block‐design temporal pattern to induce normoxia, hyperoxia and hyperoxic hypercapnia, respectively. Average T2* times were derived from measurements by two independent and blind readers in 16 standard myocardial segments on three short‐axis slices per patient. Inter‐ and intra‐reader correlations of T2* measurements were good [intra‐class correlation coefficient (ICC) = 0.75 and ICC = 0.79, both p < 0.001]. During normoxia, the mean T2* times were 29.9 ± 6.1 ms at 1.5 T and 27.1 ± 6.6 ms at 3.0 T. Both hyperoxic gases induced significant (all p < 0.01) T2* increases (?T2* hyperoxia: 1.5 T, 12.7%; 3.0 T, 11.2%; hyperoxic hypercapnia: 1.5 T, 13.1%; 3.0 T, 17.7%). Analysis of variance (ANOVA) results indicated a significant (both p < 0.001) effect of the inhaled gases on the T2* times at both 1.5 T (F = 17.74) and 3.0 T (F = 39.99). With regard to the patient imaged at 1.5 T, HRC induced significant T2* increases during hyperoxia and hyperoxic hypercapnia in normal myocardial segments, whereas the T2* response was not significant in ischemic segments (p > 0.23). The myocardial ?T2* response to HRC can reliably be imaged and quantified with BOLD CMR at both 1.5 and 3.0 T. During HRC, hyperoxia and hyperoxic hypercapnia induce a significant increase in T2*, with ?T2* being largest at 3.0 T and during hyperoxic hypercapnia in normal myocardial segments. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
996.
Background: Cigarette smoking is associated with increased rates of coronary artery disease and acute myocardial infarction (MI). Paradoxically, smokers had lower mortality after MI. The purpose of this study was to evaluate the effect of chronic smoking on myocardial performance index (MPI) in middle‐aged men after an acute MI. Material and methods: A total of 429 patients (325 smokers vs. 104 nonsmokers) presenting with acute ST elevation MI were enrolled in this study. Thrombolysis in myocardial infarction (TIMI) flow of the infarct related artery was measured before and after the primary percutaneous coronary intervention (PCI), and Gensini score was also calculated. Conventional echocardiography and tissue Doppler echocardiography (TDI) were performed within 48–72 hours after onset of chest pain. Peak early (Em) and late (Am) diastolic velocities, peak systolic (Sm) mitral annular velocities and time intervals were recorded with TDI. The MPI, ratio of Em/Am, and E/Em were calculated. Results: Baseline demographic and angiographic characteristics such as Gensini score, pre and, post PCI TIMI flow were similar in 2 groups. In contrast, LV MPI was preserved among smokers (0.59 ± 0.15 vs. 0.66 ± 0.14, P = 0.01), and Em/Am values were also higher in smokers (0.84 ± 0.28 vs. 0.75 ± 0.31, P = 0.01). Independent predictors of impaired MPI (≥0.60) were determined as nonsmoking status (odds ratio 2.940, 95% CI 0.98–5.83, P = 0.05), left anterior descending artery stenosis (odds ratio 3.196, 95% CI 1.73–5.91 P = 0.001), and, age (odds ratio 1.12, 95% CI 1.03–1.22, P = 0.01). Conclusions: Despite similar demographic and angiographic characteristics, smoker males had a paradoxically better MPI after acute MI.  相似文献   
997.
Clinical and biomechanical trials have shown that rigid internal fixation during ankle arthrodesis leads to increased rates of union and is associated with a reduced infection rate, union time, discomfort and earlier mobilisation compared with other methods. We describe our technique of ankle arthrodesis using anterior plating with a narrow dynamic compression plate (DCP). Between 2004 and 2007, 29 patients with a mean age of 24.4 years (range 18–42) had ankle arthrodesis using an anteriorly placed narrow DCP. Twenty-two patients were post-traumatic and seven were paralytic (five after spine fracture and two after common peroneal nerve injury). Follow-up was between 12 and 18 months (average 14 months). A rate of fusion of 100% was achieved at an average of 12.2 weeks. According to the Mazur ankle score, 65.5% had excellent, 20.7% good and 13.8% fair results. Ankle arthrodesis using an anteriorly placed narrow DCP is a good method to achieve ankle fusion in many types of ankle arthropathies.  相似文献   
998.
999.
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号