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   2654篇
  免费   160篇
  国内免费   22篇
耳鼻咽喉   14篇
儿科学   95篇
妇产科学   46篇
基础医学   413篇
口腔科学   47篇
临床医学   209篇
内科学   763篇
皮肤病学   37篇
神经病学   257篇
特种医学   46篇
外科学   187篇
综合类   5篇
预防医学   134篇
眼科学   6篇
药学   283篇
中国医学   21篇
肿瘤学   273篇
  2024年   2篇
  2023年   14篇
  2022年   61篇
  2021年   78篇
  2020年   48篇
  2019年   59篇
  2018年   76篇
  2017年   60篇
  2016年   69篇
  2015年   87篇
  2014年   97篇
  2013年   126篇
  2012年   210篇
  2011年   214篇
  2010年   102篇
  2009年   136篇
  2008年   221篇
  2007年   184篇
  2006年   157篇
  2005年   173篇
  2004年   177篇
  2003年   130篇
  2002年   126篇
  2001年   23篇
  2000年   14篇
  1999年   18篇
  1998年   31篇
  1997年   23篇
  1996年   16篇
  1995年   15篇
  1994年   7篇
  1993年   10篇
  1992年   6篇
  1991年   6篇
  1990年   10篇
  1989年   3篇
  1988年   6篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   5篇
  1983年   2篇
  1982年   5篇
  1980年   4篇
  1979年   2篇
  1978年   3篇
  1975年   2篇
  1973年   2篇
  1967年   3篇
  1890年   2篇
排序方式: 共有2836条查询结果,搜索用时 15 毫秒
51.
No consistently effective therapy is yet available for the treatment of chronic HBsAg, anti-HBe, HBV-DNA-positive hepatitis. A multicenter trial has shown that the response rates are not significantly different when patients with anti-HBe-positive hepatitis are treated with six-month course of thymosin-1 or of interferon-. However, since among these patients, interferon's real efficacy is still debated, with sustained biochemical response achieved in only a few of the treated patients, we conducted this controlled study to investigate the safety and efficacy of thymosin-1 as compared with no treatment. Forty-four chronic hepatitis B virus (HBV) carriers, who were anti-HBe- and HBV-DNA-positive, were randomized, with stratification for the presence of cirrhosis at baseline liver biopsy, to receive either thymosin-1 at a dose of 900 g/m2 twice a week for six months or no treatment. At entry, both groups of patients were comparable for sex, age, liver histology, ALT, IgM anti-HBc, and HBV-DNA levels. Forty-two patients were followed-up for 20 months (median; range 12–32 months) after completion of therapy: one dropped out, and one developed hepatocellular carcinoma at six months. Thymosin-1 treatment had no side effects. Six months after the end of the therapy, HBV-DNA was negative and ALT had normalized in 14% of treated cases and in 4.5% of control group, while IgM anti-HBc was negative (<0.200) in 14% of the treated patients and in 4.5% of the controls. Among the treated patients, the median ALT levels stayed significantly lower compared to the pretreatment values during the treatment period and six months of follow-up. During the first year, there were six flares of hepatitis in the control group and five among the treated patients (P = NS), yielding a per year average of 0.3 and 0.23 flares per patient, respectively. Among the treated patients, median IgM anti-HBc levels were low with respect to baseline values 4–10 months after treatment started. None became HBsAg negative. In conclusion, these results indicate that, in anti-HBe, HBV-DNA-positive chronic hepatitis B, thymosin-1 therapy alone does not increase the response rate, but may contribute to reduce the immune-mediated liver cell necrosis as indirectly assessed by ALT and IgM anti-HBc levels.  相似文献   
52.

We aimed to analyze the outcome and identify predictors of hospital mortality in patients with refractory cardiac arrest (CA) complicating acute coronary syndromes (ACS) and requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO) treatment. Between Jan-2005 and Dec-2019, 51 patients underwent urgent VA-ECMO implantation for CA in ACS. Patients were divided in two groups: “in-hospital” cardiac arrest (IHCA) and “out-of-hospital” cardiac arrest (OHCA). Prospectively collected data were retrospectively analyzed and compared between groups. Predictors for hospital mortality were investigated. IHCA and OHCA patients were 32 (62.7%) and 19 (37.3%), respectively. The groups differed for: male gender (72% vs 95%; p?=?0.070), lactate peak level (8.5?±?4.3vs10.7?±?2.9; p?=?0.023), total elapsed time from CA to VA-ECMO implantation in both groups (p?<?0.001) and elapsed time from CA (IHCA group) or hospital arrival (OHCA group) to VA-ECMO implantation (38 min vs 80 min; p?=?0.001). At logistic regression analysis, concomitant lactate level greater than 8.0 mmol/L and elapsed time from CA to VA-ECMO?≥?30 min were predictors of increased mortality (OR 3.9; 95% CI 1.19–12.79; p?=?0.025) for the entire population. In-hospital mortality was 60.8% (31/51 patients): 68.4% in OHCA group and 56.2% in IHCA group. No risk factors related to 30-day mortality resulted significant at univariable analysis. When rapidly instituted, VA-ECMO improves survival in patients with refractory cardiac arrest allowing coronary syndrome treatment. The association of an elapsed time from CA to VA-ECMO implantation longer than 30 min and a preoperative lactate peak level over 8.0 mmol/L predict a poor outcome, independently from being IHCA or OHCA.

  相似文献   
53.
54.
55.
Ketogenic diets (KDs) have beneficial effects on several diseases, such as epilepsy, mitochondriopathies, cancer, and neurodegeneration. However, little is known about their effects on aging individuals. In the present study, late-adult (19-month-old) rats were fed for 8 weeks with two medium chain triglycerides (MCT)-KDs, and the following morphologic parameters reflecting synaptic plasticity were evaluated in stratum moleculare of hippocampal CA1 region (SM CA1) and outer molecular layer of hippocampal dentate gyrus (OML DG): average area (S), numeric density (Nv(s)), and surface density (Sv) of synapses, and average volume (V), numeric density (Nv(m)), and volume density (Vv) of synaptic mitochondria. In SM CA1, MCT-KDs induced the early appearance of the morphologic patterns typical of old animals (higher S and V, and lower Nv(s) and Nv(m)). On the contrary, in OML DG, Sv and Vv of MCT-KDs-fed rats were higher (as a result of higher Nv(s) and Nv(m)) versus controls; these modifications are known to improve synaptic function and metabolic supply. The opposite effects of MCT-KDs might reflect the different susceptibility to aging processes: OML DG is less vulnerable than SM CA1, and the reactivation of ketone bodies uptake and catabolism might occur more efficiently in this region, allowing the exploitation of their peculiar metabolic properties. Present findings provide the first evidence that MCT-KDs may cause opposite morphologic modifications, being potentially harmful for SM CA1 and potentially advantageous for OML DG. This implies risks but also promising potentialities for their therapeutic use during aging.  相似文献   
56.
Allergic rhinitis is a common problem in childhood and adolescence, with a negative impact on the quality of life of patients and their families. The treatment modalities for allergic rhinitis include allergen avoidance, anti-inflammatory symptomatic treatment and allergen specific immunotherapy. In this review, four cases of children with allergic rhinitis are presented to illustrate how the recently published EAACI Guidelines on Pediatric Allergic Rhinitis can be implemented in clinical practice.  相似文献   
57.
58.
Objective: Development of an Italian matrix sentence test for the assessment of speech intelligibility in noise. Design: The development of the test included the selection, recording, optimization with level adjustment, and evaluation of speech material. The training effect was assessed adaptively during the evaluation measurements with six lists of 20 sentences, using open- and closed-set response formats. Reference data were established for normal-hearing listeners with adaptive measurements. Equivalence of the test lists was investigated using the open-set response format at three signal-to-noise ratios (SNRs). Study sample: A total of 55 normal-hearing Italian mother-tongue listeners. Results: The evaluation measurements at fixed SNRs resulted in a mean speech reception threshold (SRT) of ? 7.3 ± 0.2 dB SNR and slope of 13.3 ± 1.2 %/dB. The major training effect of 1.5 dB was observed for the first two consecutive measurements. Mean SRTs of ? 6.7 ± 0.7 dB SNR and ? 7.4 ± 0.7 dB SNR were found from the third to the sixth adaptive measurement for open- and closed-set test response formats, respectively. Conclusions: A good agreement has been found between the SRTs and slope and those of other matrix tests. Since sentences are difficult to memorize, the Italian matrix test is suitable for repeated measurements.  相似文献   
59.
60.
STUDY OBJECTIVE: To assess the clinical effectiveness of pulmonary rehabilitation (PR) after 10 or 20 consecutive sessions in outpatients with chronic airway obstruction (CAO). DESIGN: Observational prospective cohort trial. SETTING: Outpatient clinic of a rehabilitation center. PATIENTS AND INTERVENTIONS: Twenty-five outpatients (mean age, 65 +/- 9 years [+/- SD]; FEV1, 64 +/- 12% predicted) admitted to a comprehensive PR program, including exercise training. MEASUREMENTS AND RESULTS: The load reached on a cycloergometer (maximal achieved load [W-max]), the maximal and isoload dyspnea and leg fatigue on a Borg scale, 6-min walk distance (6MWD), and the health-related quality of life as assessed using the St. George's Respiratory Questionnaire (SGRQ) [total and components score] have been recorded as outcome measures at baseline, after 10 sessions (T10), and after 20 sessions (T20). The predefined criteria of the clinically significant improvement were as follows: + 15% W-max, + 54 m at 6MWD, - 1 point at isoload dyspnea and leg fatigue, and - 4% at SGRQ scores. There was a mean significant difference between changes at T20 and T10 for 6MWD (- 42.96 m; 95% confidence interval [CI], - 57.79 to - 28.12 m; p = 0.001), total SGRQ (4.80; 95% CI, 2.29 to 7.31; p = 0.001), activity SGRQ (3.60; 95% CI, 0.48 to 6.71; p = 0.025), and symptoms SGRQ (5.96; 95% CI, 2.72 to 9.2; p = 0.001). The percentage of patients who improved was different at T20 as compared with T10 for W-max (68% and 48%, respectively; p = 0.025), 6MWD (76% and 20%, p = 0.001), and total SGRQ (64% and 36%, p = 0.008). CONCLUSIONS: A 10-session course of PR provides only limited clinically significant changes of outcome measures when compared with a 20-session course in outpatients with CAO of mild-to-moderate severity.  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