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   8460篇
  免费   476篇
  国内免费   112篇
耳鼻咽喉   127篇
儿科学   151篇
妇产科学   81篇
基础医学   1408篇
口腔科学   141篇
临床医学   691篇
内科学   1777篇
皮肤病学   481篇
神经病学   626篇
特种医学   518篇
外科学   1026篇
综合类   19篇
现状与发展   1篇
一般理论   1篇
预防医学   311篇
眼科学   192篇
药学   834篇
中国医学   143篇
肿瘤学   520篇
  2024年   7篇
  2023年   74篇
  2022年   242篇
  2021年   340篇
  2020年   179篇
  2019年   231篇
  2018年   283篇
  2017年   232篇
  2016年   322篇
  2015年   400篇
  2014年   511篇
  2013年   483篇
  2012年   786篇
  2011年   773篇
  2010年   403篇
  2009年   370篇
  2008年   499篇
  2007年   428篇
  2006年   345篇
  2005年   380篇
  2004年   266篇
  2003年   224篇
  2002年   225篇
  2001年   175篇
  2000年   184篇
  1999年   130篇
  1998年   48篇
  1997年   27篇
  1996年   35篇
  1995年   15篇
  1994年   32篇
  1993年   16篇
  1992年   41篇
  1991年   44篇
  1990年   37篇
  1989年   49篇
  1988年   28篇
  1987年   30篇
  1986年   25篇
  1985年   22篇
  1984年   10篇
  1983年   6篇
  1981年   9篇
  1980年   14篇
  1979年   15篇
  1978年   7篇
  1977年   9篇
  1971年   4篇
  1970年   4篇
  1967年   4篇
排序方式: 共有9048条查询结果,搜索用时 15 毫秒
991.
ObjectivesThe purpose of this study is to compare the effectiveness of resistance and balance exercise in reducing the risk of falls for females 65-years-old or older.DesignThe study was a single blind, controlled trial, conducted over a period of 12-weeks with pre- and post-exercise assessment.Patients and methodsNinety-five participants were randomly assigned to one of three groups: resistance-training group, balance training group, control group. Resistance training group were trained to increase strength of upper, lower. Balance training group were trained to improve balance, coordination and proprioception. Outcome measurement consisted of balance ability, muscle strength, proprioception and fall efficacy.ResultsThe resistance and balance exercise group showed a statistically significant improvement in balance ability compared to the control group (P < 0.01). The resistance exercise group showed significant improvement in muscle strength compared to the balance exercise group (P < 0.01). The balance exercise group showed significant improvement in proprioception compared to the resistance exercise group (P < 0.01). Both resistance and balance exercise showed a significant improvement in fall efficacy than the control group (P < 0.01).ConclusionsWe conclude that the resistance and balance exercise have significant effects on balance ability and falls efficacy in older females.  相似文献   
992.
993.
AIM: To evaluate the significance of computed tomography (CT) findings in relation to liver chemistry and the clinical course of acute hepatitis. METHODS: Four hundred and twelve patients with acute hepatitis who underwent enhanced CT scanning were enrolled retrospectively. Imaging findings were analyzed for the following variables: gallbladder wall thickness (GWT), arterial heterogeneity, periportal tracking, number and maximum size of lymph nodes, presence of ascites, and size of spleen. The serum levels of alanine aminotransferase, alkaline phosphatase, bilirubin, albumin, and prothrombin time were measured on the day of admission and CT scan, and laboratory data were evaluated every 2-4 d for all subjects during hospitalization. RESULTS: The mean age of patients was 34.4 years, and the most common cause of hepatitis was hepatitis A virus (77.4%). The mean GWT was 5.2 mm. The number of patients who had findings of arterial heterogeneity, periportal tracking, lymph node enlargement > 7 mm, and ascites was 294 (80.1%), 348 (84.7%), 346 (84.5%), and 56 (13.6%), respectively. On multivariate logistic regression, male gender [odds ratio (OR) = 2.569, 95%CI: 1.477-4.469, P = 0.001], toxic hepatitis (OR = 3.531, 95%CI: 1.444-8.635, P = 0.006), level of albumin (OR = 2.154, 95%CI: 1.279-3.629, P = 0.004), and GWT (OR = 1.061, 95%CI: 1.015-1.110, P = 0.009) were independent predictive factors for severe hepatitis. The level of bilirubin (OR = 1.628, 95%CI: 1.331-1.991, P < 0.001) and GWT (OR = 1.172, 95%CI: 1.024-1.342,P = 0.021) were independent factors for prolonged cholestasis in multivariate analysis. CONCLUSION: In patients with acute hepatitis, GWT on CT scan was an independent predictor of severe hepatitis and prolonged cholestasis.  相似文献   
994.
AIM:To investigate anxiety and depression propensities in patients with toxic liver injury.METHODS:The subjects were divided into three groups:a healthy control group(Group 1,n=125),an acute non-toxic liver injury group(Group 2,n=124),and a group with acute toxic liver injury group caused by noncommercial herbal preparations(Group 3,n=126).These three groups were compared and evaluated through questionnaire surveys and using the Hospital Anxiety-Depression Scale(HADS),Beck Anxiety Inventory(BAI),Beck Depression Inventory(BDI),and the hypochondriasis scale.RESULTS:The HADS anxiety subscale was 4.9±2.7,5.0±3.0 and 5.6±3.4,in Groups 1,2,and 3,respectively.The HADS depression subscale in Group 3 showed the most significant score(5.2±3.2,6.4±3.4 and 7.2±3.4in Groups 1,2,and 3,respectively)(P<0.01 vs Group 1,P<0.05 vs Group 2).The BAI and BDI in Group 3showed the most significant score(7.0±6.3 and 6.9±6.9,9.5±8.6 and 8.8±7.3,10.7±7.2 and 11.6±8.5in Groups 1,2,and 3,respectively)(BAI:P<0.01 vs Group 1,P<0.05 vs Group 2)(BDI:P<0.01 vs Group1 and 2).Group 3 showed a significantly higher hypochondriasis score(8.2±6.0,11.6±7.5 and 13.1±6.5in Groups 1,2,and 3,respectively)(P<0.01 vs Group 1,P<0.05 vs Group 2).CONCLUSION:Psychological factors that present vulnerability to the temptation to use alternative medicines,such as herbs and plant preparations,are important for understanding toxic liver injury.  相似文献   
995.
We have previously shown that autophagy is required for chronological longevity in the budding yeast Saccharomyces cerevisiae. Here we examine the requirements for autophagy during extension of chronological life span (CLS) by calorie restriction (CR). We find that autophagy is upregulated by two CR interventions that extend CLS: water wash CR and low glucose CR. Autophagy is required for full extension of CLS during water wash CR under all growth conditions tested. In contrast, autophagy was not uniformly required for full extension of CLS during low glucose CR, depending on the atg allele and strain genetic background. Leucine status influenced CLS during CR. Eliminating the leucine requirement in yeast strains or adding supplemental leucine to growth media extended CLS during CR. In addition, we observed that both water wash and low glucose CR promote mitochondrial respiration proficiency during aging of autophagy-deficient yeast. In general, the extension of CLS by water wash or low glucose CR was inversely related to respiration deficiency in autophagy-deficient cells. Also, autophagy is required for full extension of CLS under non-CR conditions in buffered media, suggesting that extension of CLS during CR is not solely due to reduced medium acidity. Thus, our findings show that autophagy is: (1) induced by CR, (2) required for full extension of CLS by CR in most cases (depending on atg allele, strain, and leucine availability) and, (3) promotes mitochondrial respiration proficiency during aging under CR conditions.  相似文献   
996.

Objective

Increased liver enzymes and decreased vitamin D levels are associated with insulin resistance and type 2 diabetes. We examined liver enzymes and vitamin D levels in metabolically healthy but obese (MHO) individuals and compared the values with those of other body size phenotypes in the Korean population.

Materials/Methods

A total of 16,190 people over the age of 18 years were analyzed using data from the Fourth Korean National Health and Nutrition Examination Survey, which is a nationally representative survey. Body size phenotypes were classified into four groups by body mass index (BMI) and number of metabolic syndrome components.

Results

The prevalence of MHO was 14.9% in the entire population and 47.7% in the obese population. In a correlation analysis adjusted for age, sex, and BMI, AST and ALT levels were positively correlated with insulin resistance and cardiometabolic risk factors of the metabolic syndrome, whereas vitamin D level was negatively correlated with these variables. MHO individuals had significantly lower concentrations of AST and ALT compared to metabolically abnormal obese (MAO) subjects, although vitamin D levels were not significantly different. Furthermore, a multiple logistic regression analysis revealed that MHO individuals had lower risk of liver enzyme abnormality compared to MAO after adjusting for potential confounding factors. However, the risk of vitamin D deficiency was not significantly different among groups with different body size phenotypes.

Conclusions

Although both liver enzymes and vitamin D levels are related to insulin resistance and metabolic syndrome, only liver enzymes were independently associated with MHO phenotype.  相似文献   
997.

Background/Aims

The objective of this study was to evaluate a monoclonal antibody-based test to detect Helicobacter pylori-specific antigen in gastric aspirates from humans.

Methods

Sixty-one volunteers were enrolled in the study. All of the subjects underwent a 13C-urea breath test (UBT) before esophagogastroduodenoscopy. Gastric aspirates were analyzed for pH and ammonia and used for polymerase chain reaction (PCR), culture, and monoclonal antibody-based detection of H. pylori. Multiple biopsies of the gastric antrum and body were obtained for a rapid urease test (RUT) and histological evaluation.

Results

Thirty-six subjects were H. pylori-positive and 25 were H. pylori-negative according to the UBT results. Compared with the H. pylori-negative subjects, H. pylori-positive subjects had a higher pH (4.77±1.77 vs 3.49±1.30, p<0.05) and ammonia level (1,130.9±767.4 vs 184.2±126.3, p<0.0001). The sensitivities and specificities of the PCR test, RUT, culture test, and monoclonal antibody-based test were 100% and 72%, 89% and 100%, 47% and 100%, and 78% and 100%, respectively.

Conclusions

The monoclonal antibody-based test for diagnosing H. pylori infection in gastric aspirates has increased sensitivity compared with the culture test and specificity as high as that of the RUT. The test may be useful as an additive test for examining gastric aspirates.  相似文献   
998.

Background/Aims

Acute complicated diverticulitis can be subdivided into moderate diverticulitis and severe diverticulitis. Although there have been numerous studies on the risk factors for complicated diverticulitis, little research has focused on severe diverticulitis. This study was designed to identify the risk factors for severe diverticulitis in an acute diverticulitis attack using the modified Hinchey classification.

Methods

Patients were included if they had any evidence of acute diverticulitis detected by computed tomography. The patients were subdivided into severe diverticulitis (Hinchey class ≥Ib; abscesses or peritonitis) and moderate diverticulitis (Hinchey class Ia; pericolic inflammation) groups.

Results

Of the 128 patients, 25 exhibited severe diverticulitis, and 103 exhibited moderate diverticulitis. In a multivariate analysis, age >50 years (odds ratio [OR], 5.27; p=0.017), smoking (OR, 3.61; p=0.044), comorbidity (OR, 4.98; p=0.045), leukocytosis (OR, 7.70; p=0.003), recurrence (OR, 4.95; p=0.032), and left-sided diverticulitis (OR, 6.92; p=0.006) were significantly associated with severe diverticulitis.

Conclusions

This study suggests that the risk factors for severe diverticulitis are age >50 years, smoking, comorbidity, leukocytosis, recurrent episodes, and left-sided diverticulitis.  相似文献   
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