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   1890篇
  免费   95篇
  国内免费   15篇
耳鼻咽喉   22篇
儿科学   17篇
妇产科学   102篇
基础医学   155篇
口腔科学   25篇
临床医学   144篇
内科学   483篇
皮肤病学   28篇
神经病学   137篇
特种医学   41篇
外科学   340篇
综合类   9篇
预防医学   64篇
眼科学   60篇
药学   167篇
中国医学   3篇
肿瘤学   203篇
  2024年   1篇
  2023年   23篇
  2022年   52篇
  2021年   64篇
  2020年   42篇
  2019年   57篇
  2018年   65篇
  2017年   39篇
  2016年   56篇
  2015年   62篇
  2014年   86篇
  2013年   114篇
  2012年   179篇
  2011年   149篇
  2010年   82篇
  2009年   69篇
  2008年   152篇
  2007年   129篇
  2006年   133篇
  2005年   129篇
  2004年   95篇
  2003年   89篇
  2002年   52篇
  2001年   11篇
  2000年   10篇
  1999年   7篇
  1998年   9篇
  1997年   9篇
  1996年   4篇
  1995年   2篇
  1994年   10篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1972年   1篇
排序方式: 共有2000条查询结果,搜索用时 15 毫秒
81.
82.
The aim of this study is to investigate systemic sclerosis (SSc) patients without clinically evident heart disease for cardiac abnormalities. SSc patients and age- and sex-matched healthy controls from the hospital staff underwent transthoracic echocardiography for the assessment of the left ventricle (LV) morphology and function and estimation of the pulmonary artery systolic pressure (PASP). Patients further underwent stress-rest myocardial perfusion imaging (MPI) scintigraphy by single-photon emission computed tomography (SPECT). Thirty-seven patients were included (33 women, 19 with diffuse, and 18 with limited SSc). LV hypertrophy was more common in SSc patients than controls (24.3 vs 0 %, p?=?0.001). Impaired LV relaxation was found in 45.9 % of patients and 40.5 % controls (p?=?0.639). Excluding patients with arterial hypertension, LV hypertrophy was still found in 23.1 % and LV relaxation impairment in 38.5 %. PASP over 30 mmHg was found in 13 patients (35.1 %), 11 of whom had no history of pulmonary arterial hypertension (PAH). Of 35 patients who underwent SPECT, 21 patients (60 %) exhibited reversible LV perfusion defects. Their mean age was 51.8 years; four patients were younger than 40 years old and eight patients younger than 50 years. In all cases, ischemia was graded as mild or moderate and in a single case, graded as significant. Subclinical heart involvement is common in SSc patients even in the younger age groups. LV hypertrophy and impaired relaxation, raised PASP, and ischemia on MPI with SPECT are found in a significant proportion of SSc patients. Careful screening of SSc patients for potential heart involvement and consultation by a cardiologist may be of value.  相似文献   
83.
84.

Purpose

The aim of this study was to elucidate the magnitude of variations in oxygenation indices and the pattern of hemodynamic changes in response to the net effect of tracheal apneic oxygenation (AO) with a view to define the safe time limit of its application.

Methods

After obtaining Animal Research Ethics Committee approval, AO was applied in 12 piglets for 40 min. Arterial (a) and mixed venous (v) blood samples for oxygen (O2) and carbon dioxide (CO2) tension (PaO2/PvO2, PaCO2/PvCO2), O2 saturation (SaO2/SvO2), pHa, base excess (BEa), and bicarbonate (HCO3a) determination and for alveolar O2 tension (PAO2), PaO2/FiO2 and PaO2/PAO2 ratio, arterial–mixed venous O2 content (AVDO2), and O2 extraction ratio (O2ER) estimation were collected on anesthesia induction, 10, 20, 30, and 40 min during AO and 10 and 20 min after reconnection to the ventilator. Concomitant hemodynamic data were obtained.

Results

Besides PvO2 and PAO2, AO adversely influenced PaO2 (248–113 mmHg), PaCO2 (35–145 mmHg), PvCO2, PaO2/FiO2, and PaO2/PAO2 in a time-depended fashion, whereas SvO2, AVDO2, and O2ER were minimally affected. P(a ? v)CO2 was reversed throughout AO. Acid–base status derangement, consisting of HCO3a elevation, BEa widening, and acidemia (pH 6.9) maximized 40 min after AO. During AO, heart rate, systemic and pulmonary circulation pressures, and cardiac output were progressively elevated, whereas systemic vascular resistance was reduced. All the studied parameters reverted almost to baseline within the 20-min period of ventilator reconnection.

Conclusion

Tracheal AO for 40 min ensures acceptable blood oxygenation, promotes notable hypercapnic acidosis, and consequent transient hemodynamic alterations, which are almost completely reversible after reconnection to the ventilator.  相似文献   
85.

Introduction and hypothesis

The aim of our study was to compare air-charged and water-filled catheters simultaneously in the measurement of the intravesical, abdominal and detrusor pressure during urodynamic investigations.

Methods

Consecutive women with lower urinary tract symptoms, referred for urodynamics were prospectively studied. Readings of intravesical pressure (pves), abdominal pressure (pabd) and detrusor pressure (pdet), recorded by both the air-charged and water-filled catheters, were displayed simultaneously and compared at the end of filling, on standing, on sitting prior to voiding and at the maximum involuntary detrusor contraction. The signals (pressures) recorded by both types of catheter were compared using the Bland–Altman plot and paired samples t test.

Results

Twenty women with a mean age of 49 (range 36–72) were recruited. One patient with normal urodynamics was excluded in view of the poor quality trace. At each of the four comparison points, the air-charged catheters consistently produced higher mean pressures than the water-filled catheters. There were wide variations in the difference between the readings produced by the two types of catheter.

Conclusions

Pressures measured using air-charged catheters are not comparable with water-filled catheters and are therefore not interchangeable. Caution must be used when comparing urodynamic parameters using air-charged and water-filled catheters.  相似文献   
86.
87.

Objective

This study investigates the potential of a novel guided tissue regeneration strategy, using fully demineralized dentin infiltrated with silica and hydroxyapatite (HA) nanoparticles (NPs), to remineralize dentin collagen that is completely devoid of native hydroxyapatite.

Methods

Dentin blocks were fully demineralized with 4 N formic acid and subsequently infiltrated with silica and HA NPs. The remineralizing potential of infiltrated dentin was assessed following a twelve week exposure to an artificial saliva solution by means of TEM, EDS and micro-CT. Measurements were taken at baseline and repeated at regular intervals for the duration of the study to quantify the P and Ca levels, the mineral volume percentage and mineral separation of the infiltrated dentin specimens compared to sound dentin and non-infiltrated controls.

Results

Infiltration of demineralized dentin with nano-HA restored up to 55% of the P and Ca levels at baseline. A local increase in the concentration of calcium phosphate compounds over a period of twelve weeks resulted in a higher concentration in P and Ca levels within the infiltrated specimens when compared to the non-infiltrated controls. Remineralization of demineralized dentin with silica NPs by immersion in artificial saliva was the most effective strategy, restoring 20% of the P levels of sound dentin. Micro-CT data showed a 16% recovery of the mineral volume in dentin infiltrated with silica NPs and a significant decrease in the mineral separation to levels comparable to sound dentin.

Significance

Demineralized dentin infiltrated with silica NPs appears to encourage heterogeneous mineralization of the dentin collagen matrix following exposure to an artificial saliva solution.  相似文献   
88.
Purpose

The endeavor of deciphering intricate phenomena within the field of molecular medicine dictates the necessity to investigate tumor/disease microenvironment real-time on cellular level. We, hereby, design simple and robust intravital microscopy strategies, which can be used to elucidate cellular or molecular interactions in a fluorescent mouse model.

Procedures

We crossbred transgenic TIE2GFP mice with nude BALB/c mice, allowing the breeding of immunocompetent and immunodeficient mouse models expressing green fluorescent protein (GFP) in vascular endothelium. Then, we surgically exposed various tissues of interest to perform intravital microscopy.

Results

By utilizing simple tissue preparation procedures and confocal or two-photon microscopy, we produced high-resolution static snapshots, dynamic sequences, and 3D reconstructions of orthotopically grown mammary tumor, skin inflammation, brain, and muscle. The homogenous detection of GFP expressed by endothelial cells and a combination of fluorescence agents enabled landmarking of tumor microenvironment and precise molecular tagging.

Conclusion

Simple intravital microscopy procedures on TIE2GFP mice allowed a real-time multi-color visualization of tissue microenvironment, underlining that robust microscopy strategies are relatively simple and can be readily available for many tissues of interest.

  相似文献   
89.
ObjectivesCerebral vasospasm is a known complication to aneurysmal subarachnoid haemorrhage, which can lead to severe morbidity. Intra-arterial vasodilation therapy is widely used as a last resort treatment in patients with symptomatic refractory cerebral vasospasm but there is limited data about the outcome. The purpose of this study is to evaluate the neurological and radiological outcome in patients treated with intra-arterial nimodipine in relation to cerebral infarction, procedure-related complications and clinical outcome.MethodsPatients with refractory cerebral vasospasm treated with intra-arterial nimodipine during 2009–2020 at Sahlgrenska University Hospital were retrospectively reviewed. Neurological outcome (modified Rankin Scale) at 30 days and 6 months, development of cerebral infarction after intra-arterial nimodipine treatment and procedure-related complications were studied.ResultsForty-eight patients were treated with intra-arterial nimodipine. A good outcome (modified Rankin Scale 0–2) was seen in 25% (n = 12) of the patients after 30 days and in 47% (n = 22) of the patients after six months. Infarction related to the vasospastic vessel after treatment with intra-arterial nimodipine was seen in 60% (n = 29) of the patients. A total of 124 procedures with intra-arterial nimodipine were performed where complications were seen in 10 (21%) patients in 10 (8%) procedures. Four (8%) patients died within 30 days.ConclusionsA majority of patients developed an ischaemic cerebral infarction in spite of intra-arterial nimodipine treatment. However, a good clinical recovery was seen in almost half of the patients after 6 months. Minor complications occurred in one out of five patients.  相似文献   
90.
Hydroxytyrosol (HT) is a natural antioxidant found in olive products and characterized by well-documented beneficial effects on human health. Several research studies are ongoing that aim to investigate its potency and molecular mechanism of action. The present study aimed to investigate the potential effect of HT on human obesity through a randomized double-blind prospective design. HT in two different doses (15 and 5 mg/day) and a placebo capsule was administered to 29 women with overweight/obesity for six months and their weight and fat mass were monitored at three time points (baseline, 4, 12 and 24 weeks). Statistically significant weight and visceral fat mass loss (%weight loss: p = 0.012, %visceral fat loss: p = 0.006) were observed in the group receiving the maximum HT dosage versus placebo after 4 weeks of the intervention, with attenuation of these findings at 12 and 24 weeks of the study. Urine samples were collected during the intervention and analyzed via liquid chromatography–high-resolution mass spectrometry for untargeted metabolomic purposes and comparisons between study groups were performed. HT administration was safe and well-tolerated. To the best of our knowledge, this is the first human cohort investigating the effects of HT on obesity for a prolonged study period.  相似文献   
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