全文获取类型
收费全文 | 410篇 |
免费 | 14篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 23篇 |
妇产科学 | 2篇 |
基础医学 | 34篇 |
临床医学 | 71篇 |
内科学 | 144篇 |
神经病学 | 12篇 |
特种医学 | 16篇 |
外科学 | 12篇 |
综合类 | 38篇 |
预防医学 | 42篇 |
眼科学 | 1篇 |
药学 | 27篇 |
中国医学 | 15篇 |
肿瘤学 | 14篇 |
出版年
2023年 | 6篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 25篇 |
2013年 | 45篇 |
2012年 | 19篇 |
2011年 | 31篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 30篇 |
2007年 | 21篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 12篇 |
2003年 | 9篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有453条查询结果,搜索用时 15 毫秒
1.
2.
《International journal of hygiene and environmental health》2019,222(7):991-1000
IntroductionTraining fires may constitute a major portion of some firefighters’ occupational exposures to smoke. However, the magnitude and composition of those exposures are not well understood and may vary by the type of training scenario and fuels.ObjectivesTo understand how structure fire training contributes to firefighters' and instructors’ select chemical exposures, we conducted biological monitoring during exercises involving combustion of pallet and straw and oriented strand board (OSB) or the use of simulated smoke.MethodsUrine was analyzed for metabolites of polycyclic aromatic hydrocarbons (PAHs) and breath was analyzed for volatile organic compounds (VOCs) including benzene.ResultsMedian concentrations of nearly all PAH metabolites in urine increased from pre-to 3-hr post-training for each scenario and were highest for OSB, followed by pallet and straw, and then simulated smoke. For instructors who supervised three trainings per day, median concentrations increased at each collection. A single day of OSB exercises led to a 30-fold increase in 1-hydroxypyrene for instructors, culminating in a median end-of-shift concentration 3.5-fold greater than median levels measured from firefighters in a previous controlled-residential fire study. Breath concentrations of benzene increased 2 to 7-fold immediately after the training exercises (with the exception of simulated smoke training). Exposures were highest for the OSB scenario and instructors accumulated PAHs with repeated daily exercises.ConclusionsDermal absorption likely contributed to the biological levels as the respiratory route was well protected. Training academies should consider exposure risks as well as instructional objectives when selecting training exercises. 相似文献
3.
《Journal of Cardiovascular Computed Tomography》2019,13(2):113-117
ObjectivesTo evaluate the feasibility of coronary computed tomography angiography (CCTA) in patients with free-breathing using 16-cm z-coverage CT with motion correction algorithm.Methods616 patients underwent CCTA without heart rate control. 325 examinations were performed during breath-holding (group A), and the remaining 291 were performed during free-breathing (group B). The image quality scores were defined as 1 (excellent), 2 (good), 3 (adequate), and 4 (poor). 22 patients in group A and 24 in group B underwent invasive coronary angiography (ICA) after CCTA within two weeks. The image quality score, diagnostic accuracy using ICA as reference, signal-to-noise ratio (SNR), and effective dose (ED) were compared between the two groups.ResultsMean heart rate during scanning was 70.8 ± 13.8 bpm in group A and 70.7 ± 13.2 bpm in group B (P = .950). No significant differences were observed in SNR and image quality score (1.49 ± 0.62 vs. 1.53 ± 0.67; P = .647) between the breath-holding and free-breathing groups. ED (1.99 ± 0.83 mSv vs. 2.01 ± 0.88 mSv) was not significantly different between the two groups (P = .975). In a segment-based analysis, the sensitivity, specificity and diagnostic accuracy in the detection of coronary stenosis of more than 50% were 82.1%, 96.8% and 92.2%, respectively in the breath-holding group and 82.2%, 96.6% and 92.2%, respectively in the free-breathing group with no significant differences for these parameters between the two groups.ConclusionsCCTA for patients without heart rate control and during free-breathing using 16-cm z-coverage CT with motion correction algorithm showed no significant difference in image quality and diagnostic performance compared with CCTA during breath-holding. 相似文献
4.
Chizoba Wonodi Chisom Obi‐Jeff Adegoke Falade Kevin Watkins Oluseyi A. Omokore 《Pediatric pulmonology》2020,55(Z1):S5-S9
Pneumonia is the leading cause of child deaths in Nigeria. Interventions to combat pneumonia are known and globally available, but not yet deployed effectively in Nigeria. While the under‐five pneumonia deaths dropped globally by 51% during the Millennium Development Goals (MDG) years (2000 to 2015), the rate declined by a mere 8% in Nigeria. In this commentary, we focus on three factors that may have stalled Nigeria's progress on pneumonia control. First, a chronically weak health system failed to deliver the needed services at scale. Second, strong coordination of a multipronged and well‐funded push against pneumonia was absent. Third, sound and timely data on pneumonia intervention coverage were lacking, thus blunting the accountability mechanisms that could have driven quick, targeted action. In response, the Federal Ministry of Health recently developed a National Pneumonia Control Strategy with the support of the “Every Breath Counts Coalition” (EBCC). This strategy, a first of its kind, articulates a common vision for reducing pneumonia‐led morbidity and mortality and provides a unified approach to respond comprehensively to pneumonia within and outside the health sector. Strong political will and sustainable financing are now needed to effectively implement this strategy and accelerate progress on pneumonia control. This will contribute hugely to achieving the government's health goals, the Sustainable Development Goal (SDG) 3.2 and the Global Action Plan on Pneumonia and Diarrhoea (GAPPD) targets. 相似文献
5.
6.
7.
8.
目的:对16例肠易激综合征(IBS)患者胃肠运动功能进行临床分析,为临床研究肠易激综合征的发病机制及临床药物治疗提供理论依据。方法:对16例肠易激综合征患者进行食管动态pH监测、胃电检测和呼吸氢试验分析。结果:肠易激综合征患者进餐前、后胃电变化较对照组明显(t=-8.437,t=-7.126;P〈0.01),胃电变异指数、肠道传递时间与对照组有显著性差异(t=-2.312,t=-1.694,t=-9.163,t=-7.894;P〈0.01)。结论:肠易激综合征患者消化吸收及肠道运动功能异常可能是由于肠道电生理活动异常而引起。 相似文献
9.
A. E. Bharucha M. Camilleri E. Veil D. Burton A. R. Zinsmeister 《Neurogastroenterology and motility》2013,25(1):e60-e69
Background The [13C]‐Spirulina platensis gastric emptying breath test (GEBT) with five samples is accurate relative to scintigraphy. This study was primarily designed to further validate this GEBT using a slightly different process for incorporating [13C] in Spirulina and to evaluate the utility of additional samples for assessing early gastric emptying. Methods After a 223 kcal, test meal labeled with 99mTc and [13C]‐S. platensis, scintigraphic images, and five breath samples (45, 90, 120, 180, and 240 min, GEBT5) were collected in 14 controls (Part A). In Part B, nine breath samples were collected at 15, 30, 45, 60, 90, 120, 150, 180, and 240 min (GEBT9) in 30 subjects (15 controls, 15 dyspepsia). Using correlation between [13C] breath excretion and scintigraphic emptying, lag time (t10, time for 10% emptying), emptying at 30 min (GE30), and half time (t50) were estimated for GEBT5 (Parts A and B) and GEBT9 (Part B). Key Results Half time values for scintigraphy, GEBT5, and GEBT9 were highly concordant. t10 by GEBT9 (90%CI, 6–15 min) was more strongly correlated [CCC 0.80 (95% CI, 0.63–0.90)] with scintigraphy (90% CI, 5–12 min), than GEBT5 [10–19 min, CCC 0.73 (95% CI, 0.54–0.85)]. The correlation between estimated values (GEBT9) and linearly interpolated values (GEBT5) was closer at 60 [CCC 0.95 (95% CI, 0.91–0.97)] than 30 min [CCC 0.81 (95% CI, 0.71–0.89)]. Conclusions & Inferences The [13C]‐S. platensis GEBT can accurately measure GE. While 5‐ and 9‐samples are equally accurate for measuring t50, GEBT9 provides a more comprehensive assessment of early GE (t10 and GE30). 相似文献
10.
V. Savarino A. Sulli P. Zentilin M. Raffaella Mele M. Cutolo 《Scandinavian journal of gastroenterology》2013,48(12):1251-1254
Background: Raynaud phenomenon (RP) is a vasospastic condition that manifests itself as cold-induced ischemic attacks of the fingers with skin color changes. It may be classified as primary (PRP) or secondary (SRP), if associated to other diseases, mainly connective-tissue diseases. Recently, the association between PRP and Helicobacter pylori infection has been reported. The aims of this study were to evaluate the prevalence of gastric H. pylori infection in a large group of patients affected by PRP and SRP and to assess whether it was more evident in patients with more recent onset of RP. Methods: Ninety-eight consecutive patients (93 F and 5 M), referring to our videocapillaroscopic service for the diagnosis of vascular and connective-tissue diseases, were evaluated. Forty-nine of them were affected by PRP and 49 by SRP. Patients were classified as having PRP on the basis of normal serological and immunological findings, normal videocapillaroscopic examination and exclusion of other conditions inducing RP. H. pylori infection was diagnosed by 13C-urea breath test (UBT). Two groups of 49 age-and sex-matched controls, respectively, were also evaluated. Results: Patients with SRP resulted significantly older than those with PRP (P < 0.006). UBT was found positive in 22/49 patients with PRP (45%) and in 29/49 patients with SRP (59%). The positivity of the respective control groups was 36% and 53% (P = NS). There was no higher prevalence of H. pylori infection in patients with RP lasting for less than 4 years. Conclusions: The results do not confirm the previously reported high prevalence of H. pylori infection in patients with PRP. A high association was not even found between the presence of the microorganism and SRP. There was no difference in the prevalence of H. pylori infection among the subgroups with more recent onset of both PRP and SRP. 相似文献