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   16753篇
  免费   769篇
  国内免费   39篇
耳鼻咽喉   288篇
儿科学   893篇
妇产科学   414篇
基础医学   1429篇
口腔科学   296篇
临床医学   1291篇
内科学   3980篇
皮肤病学   253篇
神经病学   807篇
特种医学   585篇
外科学   2953篇
综合类   356篇
一般理论   2篇
预防医学   895篇
眼科学   737篇
药学   1249篇
  5篇
中国医学   55篇
肿瘤学   1073篇
  2024年   76篇
  2023年   158篇
  2022年   276篇
  2021年   633篇
  2020年   354篇
  2019年   513篇
  2018年   581篇
  2017年   388篇
  2016年   383篇
  2015年   403篇
  2014年   623篇
  2013年   793篇
  2012年   1209篇
  2011年   1082篇
  2010年   674篇
  2009年   527篇
  2008年   796篇
  2007年   799篇
  2006年   757篇
  2005年   710篇
  2004年   632篇
  2003年   519篇
  2002年   487篇
  2001年   384篇
  2000年   419篇
  1999年   311篇
  1998年   137篇
  1997年   110篇
  1996年   97篇
  1995年   93篇
  1994年   80篇
  1993年   67篇
  1992年   216篇
  1991年   196篇
  1990年   177篇
  1989年   168篇
  1988年   139篇
  1987年   133篇
  1986年   135篇
  1985年   131篇
  1984年   109篇
  1983年   112篇
  1982年   54篇
  1981年   56篇
  1979年   94篇
  1978年   65篇
  1974年   55篇
  1973年   81篇
  1972年   77篇
  1971年   58篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
In 2019, the newly emerged SARS-CoV-2 virus caused pneumonia-like illness. The disease rapidly spread globally, leading to a worldwide outbreak referred to as the COVID-19 pandemic. The affected patients show symptoms of fever, dry cough, respiratory distress, myalgia, and gastrointestinal disturbance. As of April 5, 2021, 132,083,022 people worldwide were affected by COVID-19, while 2,868,454 people died due to the disease[1]. SARS-CoV-2-positive patients may remain asymptomatic or start showing symptoms in 2?14 days after exposure to the virus[2]. The viral infection can be diagnosed from nasopharyngeal, throat, alveolar lavage, lacrimal, blood, and stool samples. The patient starts shedding the virus in stool regardless of being symptomatic or asymptomatic, which makes sewage-based detection of the virus to be more beneficial in the early infection stage.  相似文献   
22.

Summary

We studied the relationships among strength, muscle mass, and bone mineral density (BMD) with lifestyle change. Lifestyle therapy consisted of exercise, diet, and diet plus exercise. Diet was by caloric restriction to induce and maintain a weight loss of 10 % from baseline body weight. Exercise attenuated weight loss-induced muscle and bone losses. Exercise improved strength despite muscle loss in patients on diet and exercise. Changes in strength did not correlate with changes in BMD. However, changes in thigh muscle volume correlated with, and predicted changes in hip BMD.

Introduction

Losses of hip BMD and lean body mass are major complications of lifestyle therapy in frail, obese older adults; however, the contribution of mechanical strain loss from muscle loss is poorly defined. We determined the effect of changes in thigh muscle volume and muscle strength on BMD in frail, obese older adults undergoing lifestyle therapy aimed at intentional weight loss with or without exercise.

Methods

One hundred seven obese older adults were randomized to control, diet, exercise, and diet–exercise groups for 1 year. Thigh muscle volume was measured by magnetic resonance imaging, BMD by DXA, knee strength by dynamometry, total strength by one-repetition maximum (1-RM), and bone markers by immunoassay.

Results

Thigh muscle volume decreased in the diet group (?6.2?±?4.8 %) and increased in the exercise group (2.7?±?3.1 %), while it was not significantly different from the control in the diet–exercise group. Changes in hip BMD followed similar pattern as those in thigh muscle volume. Knee extension and flexion increased in the exercise group (23?±?20 %; 25?±?19 %) and diet–exercise group (20?±?19 %; 20.6?±?27 %) but were unchanged in the control and diet groups. Changes in thigh muscle volume correlated with changes in hip BMD (r?=?0.55, P?=?<0.001) and were an independent predictor of changes in hip BMD (β?=?0.12, P?=?0.03) in the multiple regression analyses after accounting for demographic factors and changes in weight and physical activity. There were no correlations between BMD changes and knee strength, 1-RM, and sclerostin changes.

Conclusions

Changes in thigh muscle volume predict hip BMD changes in obese older patients undergoing lifestyle therapy. The effect of exercise in attenuating thigh muscle loss when added to diet may in part account for the reduction in weight loss-induced bone loss in the diet–exercise group.  相似文献   
23.

Background:

The most common definitions of large volume liposuction refer to total 5 l volume aspiration during a single procedure (fat plus wetting solution). Profound haemodynamic and metabolic alterations can accompany large volume liposuction. Due to paucity of literature on the effect of different tumescent solutions on the electrolyte balance and haematological changes during large volume liposuction, we carried out this study using two different wetting solutions to study the same.

Materials and Methods:

Total 30 patients presenting with varying degrees of localized lipodystrophy in different body regions were enrolled for the study. Prospective randomized controlled trial was conducted by Department of Plastic and Cosmetic Surgery, Sir Ganga Ram Hospital, New Delhi from January 2011 to June 2012. Patients were randomized into two groups of 15 patients each by using computer generated random numbers. Tumescent formula used for Group A (normal saline [NS]) was our modification of Klein''s Formula and Tumescent formula used for Group B (ringer lactate [RL]) was our modification of Hunstadt''s formula. Serum electrolytes and hematocrit levels were done at preinduction, immediate postoperative period and postoperative day 1.

Result:

Statistical analysis was performed using SPSS software version 15.0. Which showed statistically significant electrolytes and hematocrit changes occur during large volume liposuction.

Conclusion:

Statistically significant electrolytes and hematocrit changes occur during large volume liposuction and patients should be kept under observation of anaesthesist for at least 24 h. Patients require strict monitoring of vital parameters and usually Intensive Care Unit is not required. There was no statistical difference in the electrolyte changes using NS or RL as tumescent solution and both solutions were found safe for large volume liposuction.KEY WORDS: Electrolyte changes during liposuction, haemogram changes during liposuction, large volume liposuction  相似文献   
24.
According to the Hunter Serotonin Toxicity Criteria, the presence of either clonus or hyperreflexia is a must for making a diagnosis of serotonin syndrome (SS). We report five patients with SS who had areflexia because of associated polyneuropathy. None of the patients fulfilled the Hunter criteria for SS. However, all five patients had features suggestive of neuromuscular hyperactivity, autonomic hyperactivity and altered mental status and fulfilled the Sternbach criteria for SS. All patients responded to cyproheptadine within 5 days to 2 weeks duration. These cases highlight the limitations of the Hunter criteria for SS in patients with associated polyneuropathy.  相似文献   
25.
26.
Background contextCauda equina syndrome is caused by compression or injury to the nerve roots distal to the level of the spinal cord. This syndrome presents as low back pain, motor and sensory deficits in the lower extremities, and bladder as well as bowel dysfunction. Although various etiologies of cauda equina syndrome have been reported, a less common cause is infection.PurposeTo report a case of cauda equina syndrome caused by infection of an intradural extramedullary abscess with Staphylococcus aureus.Study design/settingCase report and review of the literature.MethodsThe literature regarding the infectious causes of cauda equina syndrome was reviewed and a case of cauda equina syndrome caused by infection of an intradural extramedullary abscess with Staphylococcus aureus was reported.ResultsA 37-year-old woman, with history of intravenous drug abuse, hepatitis C, and hepatitis B, presented with low back pain lasting 2 months, lower extremity pain, left greater than right with increasing weakness and difficulty ambulating, and urinary and fecal incontinence. Her presentation was consistent with cauda equina syndrome. The patient underwent a T12–L2 laminectomy, and intradural exploration revealed an abscess. Methicillin-resistant Staphylococcus aureus was found on wound culture.ConclusionsCauda equina syndrome, presenting as a result of spinal infection, such as the case reported here, is extremely rare but clinically important. Surgical intervention is generally the recommended therapeutic modality.  相似文献   
27.
This paper presents a non-invasive method of assessing healing by measurement of fracture stiffness. The method works on the principle that if the load (F) applied at a certain known distance (Y) from the fracture is measured, then the moment (M = FY) at the fracture site can be calculated. By measuring the angle/deflection (θ) occurring at the fracture site using a suitable instrument (electrogoniometer), the necessary data to calculate fracture stiffness (FY/θ) would be available. The method was employed to assess the stiffness in a series of tibial shaft fractures treated conservatively, all of which healed uneventfully. This paper concentrates on a group of tibial shaft fractures in which the radiological criteria for fracture union were not satisfied even after a mean duration of 20 weeks treatment. The non-invasive method of measuring fracture stiffness supported the clinical impression of union in most cases at the first test, but was repeated on two more occasions to confirm the trend of progressive healing. The objective evaluation of fracture healing led to avoidance of surgical intervention in these patients, who went on to sound union.  相似文献   
28.
The contribution of elevated glucagon-like peptide 1 (GLP-1) to postprandial glucose metabolism after Roux-en-Y gastric bypass (RYGB) has been the subject of uncertainty. We used exendin-9,39, a competitive antagonist of GLP-1, to examine glucose metabolism, islet hormone secretion, and gastrointestinal transit in subjects after RYGB and in matched control subjects. Subjects were studied in the presence or absence of exendin-9,39 infused at 300 pmol/kg/min. Exendin-9,39 resulted in an increase in integrated postprandial glucose concentrations post-RYGB (3.6 ± 0.5 vs. 2.0 ± 0.4 mol/6 h, P = 0.001). Exendin-9,39 decreased insulin concentrations (12.3 ± 2.2 vs. 18.1 ± 3.1 nmol/6 h, P = 0.002) and the β-cell response to glucose (ϕTotal, 13 ± 1 vs. 11 ± 1 × 10−9 min−1, P = 0.01) but did not alter the disposition index (DI). In control subjects, exendin-9,39 also increased glucose (2.2 ± 0.4 vs. 1.7 ± 0.3 mol/6 h, P = 0.03) without accompanying changes in insulin concentrations, resulting in an impaired DI. Post-RYGB, acceleration of stomach emptying during the first 30 min by exendin-9,39 did not alter meal appearance, and similarly, suppression of glucose production and stimulation of glucose disappearance were unaltered in RYGB subjects. These data indicate that endogenous GLP-1 has effects on glucose metabolism and on gastrointestinal motility years after RYGB. However, it remains uncertain whether this explains all of the changes after RYGB.  相似文献   
29.

Background:

Percutaneous aspiration of abscesses under ultrasonography (USG) and computer tomography (CT) scan has been well described. With recurrence rate reported as high as 66%. The open drainage and percutaneous continuous drainage (PCD) has reduced the recurrence rate. The disadvantage of PCD under CT is radiation hazard and problems of asepsis. Hence a technique of clinically guided percutaneous continuous drainage of the psoas abscess without real-time imaging overcomes these problems. We describe clinically guided PCD of psoas abscess and its outcome.

Materials and Methods:

Twenty-nine patients with dorsolumbar spondylodiscitis without gross neural deficit with psoas abscess of size >5 cm were selected for PCD. It was done as a day care procedure under local anesthesia. Sequentially, aspiration followed by guide pin-guided trocar and catheter insertion was done without image guidance. Culture sensitivity was done and chemotherapy initiated and catheter kept till the drainage was <10 ml for 48 hours. Outcome assessment was done with relief of pain, successful abscess drainage and ODI (Oswestry Disability Index) score at 2 years.

Results:

PCD was successful in all cases. Back and radicular pain improved in all cases. Average procedure time was 24.30 minutes, drain output was 234.40 ml, and the drainage duration was 7.90 days. One patient required surgical stabilisation due to progression of the spondylodiscitis resulting in instability inspite of successful drainage of abscess. Problems with the procedure were noticed in six patients. Multiple attempts (n = 2), persistent discharge (n = 1) for 2 weeks, blocked catheter (n = 2) and catheter pull out (n = 1) occurred with no effect on the outcome. The average ODI score improved from 62.47 to 5.51 at 2 years.

Conclusions:

Clinically guided PCD is an efficient, safe and easy procedure in drainage of psoas abscess.  相似文献   
30.
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