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   1074961篇
  免费   71766篇
  国内免费   1369篇
耳鼻咽喉   15015篇
儿科学   34613篇
妇产科学   28623篇
基础医学   153398篇
口腔科学   29563篇
临床医学   94917篇
内科学   203708篇
皮肤病学   24391篇
神经病学   81449篇
特种医学   42968篇
外国民族医学   201篇
外科学   163139篇
综合类   21702篇
现状与发展   1篇
一般理论   263篇
预防医学   74608篇
眼科学   24537篇
药学   86129篇
  7篇
中国医学   2806篇
肿瘤学   66058篇
  2019年   7756篇
  2018年   11295篇
  2017年   8910篇
  2016年   10097篇
  2015年   11266篇
  2014年   15274篇
  2013年   22206篇
  2012年   30557篇
  2011年   32299篇
  2010年   18961篇
  2009年   17820篇
  2008年   29959篇
  2007年   32083篇
  2006年   32709篇
  2005年   31037篇
  2004年   29726篇
  2003年   28564篇
  2002年   27533篇
  2001年   60024篇
  2000年   61478篇
  1999年   50929篇
  1998年   12447篇
  1997年   11003篇
  1996年   11015篇
  1995年   10324篇
  1994年   9345篇
  1993年   8862篇
  1992年   37791篇
  1991年   36278篇
  1990年   35749篇
  1989年   34289篇
  1988年   30868篇
  1987年   29989篇
  1986年   28222篇
  1985年   26451篇
  1984年   19189篇
  1983年   16115篇
  1982年   8822篇
  1979年   17030篇
  1978年   11404篇
  1977年   10229篇
  1976年   8837篇
  1975年   10068篇
  1974年   11651篇
  1973年   11273篇
  1972年   10754篇
  1971年   10093篇
  1970年   9252篇
  1969年   8938篇
  1968年   7918篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
11.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  相似文献   
12.
13.
There is a great deal of interest in developing less invasive markers for monitoring airway inflammation and the effect of possible novel anti-inflammatory therapies that may take time to impact on disease pathology. Exhaled nitric oxide (eNO) has been shown to be a reproducible, noninvasive indicator of the inflammatory status of the airway in the clinic. The aim of the present study was to determine the usefulness of measuring eNO as a marker of the anti-inflammatory impact of glucocorticoid and an inhibitor of kappaB kinase-2 (IKK-2) inhibitor 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1), in a pre-clinical model of airway inflammation. Rats were given vehicle, budesonide or TPCA-1 prior to exposure to lipopolysaccharide, previously shown to induce an increase in eNO and airway neutrophilia/eosinophilia. Comparison of the effect of the two compounds on inflammatory components demonstrated a significant correlation between the impact on eNO and inflammatory cell burden in the airway. The current study demonstrates the usefulness of profiling potential disease-modifying therapies on exhaled nitric oxide levels and the way in which an effect on this noninvasive biomarker relates to effects on pathological parameters such as lung cellularity. Information from studies such as the current one would suggest that the measurement of exhaled nitric oxide has potential for monitoring inflammatory status in lung tissue.  相似文献   
14.
Chronic obstructive pulmonary disease (COPD) is characterised by a local pulmonary inflammatory response to respiratory pollutants and by systemic inflammation. Tumour necrosis factor (TNF)-alpha has been implicated in systemic effects of COPD and operates by binding the p55 (R1) and p75 (R2) TNF-alpha receptors. To investigate the contribution of each TNF-alpha receptor in the pathogenesis of COPD, the present study examined the effects of chronic air or cigarette smoke (CS) exposure in TNF-alpha R1 knockout (KO) mice, TNF-alpha R2 KO mice and wild type (WT) mice. CS was found to significantly increase the protein levels of soluble TNF-alpha R1 (by four-fold) and TNF-alpha R2 (by 10-fold) in the bronchoalveolar lavage of WT mice. After 3 months, CS induced a prominent pulmonary inflammatory cell influx in WT and TNF-alpha R1 KO mice. In TNF-alpha R2 KO mice, CS-induced pulmonary inflammation was clearly attenuated. After 6 months, no emphysema was observed in CS-exposed TNF-alpha R2 KO mice in contrast to WT and TNF-alpha R1 KO mice. CS-exposed WT and TNF-alpha R1 KO mice failed to gain weight, whereas the body mass of TNF-alpha R2 KO mice was not affected. These current findings suggest that both tumour necrosis factor-alpha receptors contribute to the pathogenesis of chronic obstructive pulmonary disease, but tumour necrosis factor-alpha receptor-2 is the most active receptor in the development of inflammation, emphysema and systemic weight loss in this murine model of chronic obstructive pulmonary disease.  相似文献   
15.
Severe tuberculosis (TB) requiring intensive care unit (ICU) care is rare but commonly known to be of markedly bad prognosis. The present study aimed to describe this condition and to determine the mortality rate and risk factors associated with mortality. Patients with confirmed TB admitted to ICU between 1990 and 2001 were retrospectively identified and enrolled. Clinical, radiological and bacteriological data at admission and during hospital stay were recorded. A multivariate analysis was performed to identify the predictive factors for mortality. A total of 58 TB patients (12 females, mean age 48 yrs) admitted to ICU were included. Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score at admission was 13.1+/-5.6 and 22 of 58 (37.9%) patients required mechanical ventilation. The in-hospital mortality was 15 of 58 (25.9%); 13 (22.4%) patients died in the ICU. The mean survival of patients who died was 53.6 days (range 1-229), with 50% of the patients dying within the first 32 days. The factors independently associated with mortality were: acute renal failure, need for mechanical ventilation, chronic pancreatitis, sepsis, acute respiratory distress syndrome, and nosocomial pneumonia. These data indicate a high mortality of patients with tuberculosis requiring intensive care unit care and identifies new independently associated risk factors.  相似文献   
16.
17.
Although studies have documented underuse of controller medications and overuse of short-acting inhaled ss(2)-agonist among children with persistent asthma in disadvantaged communities, the persistence of oral ss(2)-agonist use in pediatric practice has not been studied since inhaled short-acting ss(2)-agonists became widespread. We describe medications used to treat asthma among children 3 to 5 years of age at 10 Head Start and other subsidized preschool centers in East and Central Harlem, New York City. We interviewed 149 parents/guardians of children who were identified as having probable asthma based on physician's diagnosis, persistent symptoms, hospitalization, and medication use. We classified 86 of the 149 children (58%) as having current persistent asthma. Only 15 of them (17%) were reported to have used controller medications at least 5 days/week in the last 4 weeks-only 2 of whom used inhaled corticosteroids. By contrast, 53 children (62%) used oral ss(2)-agonist in the last 4 weeks, often (72%) in conjunction with nebulized or inhaled short-acting ss(2)-agonist. Use of oral ss(2)-agonist was associated with more severe symptoms. This study documents the continued widespread use of oral ss(2)-agonist for treatment of children in a low-income community with high prevalence of asthma.  相似文献   
18.
19.
20.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  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