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   909篇
  免费   51篇
  国内免费   6篇
耳鼻咽喉   4篇
儿科学   25篇
妇产科学   12篇
基础医学   140篇
口腔科学   12篇
临床医学   65篇
内科学   239篇
皮肤病学   8篇
神经病学   84篇
特种医学   29篇
外科学   137篇
综合类   7篇
一般理论   2篇
预防医学   46篇
眼科学   1篇
药学   80篇
中国医学   4篇
肿瘤学   71篇
  2023年   5篇
  2022年   21篇
  2021年   22篇
  2020年   9篇
  2019年   12篇
  2018年   15篇
  2017年   8篇
  2016年   16篇
  2015年   19篇
  2014年   29篇
  2013年   15篇
  2012年   43篇
  2011年   49篇
  2010年   38篇
  2009年   35篇
  2008年   40篇
  2007年   43篇
  2006年   50篇
  2005年   44篇
  2004年   59篇
  2003年   34篇
  2002年   31篇
  2001年   32篇
  2000年   20篇
  1999年   18篇
  1998年   9篇
  1997年   4篇
  1996年   7篇
  1995年   8篇
  1992年   20篇
  1991年   14篇
  1990年   9篇
  1989年   24篇
  1988年   17篇
  1987年   13篇
  1986年   23篇
  1985年   15篇
  1984年   11篇
  1983年   9篇
  1980年   3篇
  1979年   8篇
  1978年   4篇
  1976年   3篇
  1974年   4篇
  1972年   5篇
  1970年   7篇
  1969年   7篇
  1968年   4篇
  1967年   10篇
  1966年   3篇
排序方式: 共有966条查询结果,搜索用时 46 毫秒
91.
The aim of this study was to evaluate the efficacy of a mobile laminar airflow (LAF) unit in reducing bacterial contamination at the surgical area in an operating theatre supplied with turbulent air ventilation. Bacterial sedimentation was evaluated during 76 clean urological laparotomies; in 34 of these, a mobile LAF unit was added. During each operation, settle plates were placed at four points in the operating theatre (one at the patient area and three at the perimeter), a nitrocellulose membrane was placed on the instrument table and an additional membrane near the wound. During four operations, particle counting was performed to detect particles > or =0.5 microm. Mean bacterial sedimentation on the nitrocellulose membrane on the instrument table was 2730 cfu/m(2)/h under standard ventilation conditions, whereas it decreased significantly to a mean of 305 cfu/m(2)/h when the LAF unit was used, i.e. within the suggested limit for ultraclean operating theatres (P=0.0001). The membrane near the wound showed a bacterial sedimentation of 4031 cfu/m(2)/h without the LAF unit and 1608 cfu/m(2)/h with the unit (P=0.0001). Particle counts also showed a reduction when the LAF unit was used. No significant difference was found at the four points in the operating theatre between samplings performed with, and without, the LAF unit. Use of a mobile LAF unit with turbulent air ventilation can reduce bacterial contamination at the surgical area in high-risk operations (e.g. prosthesis implant).  相似文献   
92.
Renal artery stent implantation is associated with high rates of restenosis, particularly in vessels less than 4.5 mm in diameter. We describe 4-year follow-up results in the first patient to receive renal artery brachytherapy for this indication. A 68-year-old man who presented with flash pulmonary edema, hypertension and renal impairment was found to have severe bilateral renal artery stenosis and was treated with bilateral stent implantation. Following clinical deterioration due to severe in-stent restenosis, he underwent repeat angioplasty followed by intra-stent brachytherapy. To our knowledge, this is the first use of such therapy and hence the 4-year follow-up demonstrating excellent bilateral patency is the longest to date.  相似文献   
93.
OBJECTIVE: Systemic lupus erythematosus and rheumatoid arthritis represent independent risk factors for atherosclerosis (ATS), although this may be confounded by continuous pharmacologic treatment. Primary Sj?gren's syndrome (SS) shares several features of these diseases and may therefore represent an interesting model for verifying the presence of accelerated ATS in the absence of pharmacologic interference. The present study therefore used this model to describe the presence of accelerated ATS in a group of young women. METHODS: Thirty-seven untreated white women with primary SS were evaluated clinically and serologically. Carotid and femoral artery intima-media thickness (IMT) was evaluated in the patients and in 35 age-matched healthy women who served as controls. RESULTS: The patients had a higher IMT than did the controls at both the carotid (mean +/- SD 0.82 +/- 0.24 mm versus 0.63 +/- 0.20 mm; P < or = 0.001) and the femoral (0.81 +/- 0.26 mm versus 0.67 +/- 0.23 mm; P < or = 0.019) levels, and had a higher prevalence of carotid intima-media thickening (49% versus 11% of controls; P < or = 0.001). The patient subset with high carotid IMT showed an increased prevalence of leukopenia and circulating anti-SSA antibodies; interestingly, the number of leukocytes was inversely correlated with the level of arterial IMT in patients with SS. Multivariate analysis demonstrated that anti-SSA antibodies were independent predictors of carotid artery thickening, while leukopenia was a predictor of both carotid and femoral artery thickening. CONCLUSION: Subclinical ATS was evident in about one-half of the patients with SS. Its association with some features typical of connective tissue diseases, such as the presence of anti-SSA and leukopenia, suggests that the immune dysregulation characterizing this autoimmune disorder may play a key role in inducing early ATS.  相似文献   
94.
We report the case of a 36-year-old woman admitted for cryptogenic stroke, in whom the Patent Foramen Ovale (PFO) diameter measurement, with a purpose built sizing balloon, performed before the closure procedure, was complicated with the rupture of the inter-atrial septum generating an Atrial Septal Defect (ASD) with a significant left-to-right shunt. This kind of complication may not be easy to handle, changing the initial procedural strategy from PFO to ASD closure technique requiring specific material and operator's technical skill.  相似文献   
95.
BACKGROUND & AIMS: We have recently documented the efficacy of a highly concentrated probiotic preparation (VSL#3) in the prevention of flare-up in patients with chronic pouchitis. The aim of this study was to compare probiotic therapy with VSL#3 versus placebo in the ability to prevent the onset of acute pouchitis during the first year after ileal pouch-anal anastomosis. METHODS: Forty consecutive patients who underwent ileal pouch-anal anastomosis for ulcerative colitis were randomized to receive either VSL#3 (1 packet containing 900 billion bacteria/day) (n = 20) or an identical placebo (n = 20) immediately after ileostomy closure for 1 year. The patients were assessed clinically, endoscopically, and histologically after 1, 3, 6, 9, and 12 months. Health-related quality of life was assessed using the Inflammatory Bowel Disease Questionnaire. RESULTS: Two of the 20 patients (10%) treated with VSL#3 had an episode of acute pouchitis compared with 8 of the 20 patients (40%) treated with placebo (log-rank test, z = 2.273; P < 0.05). Treatment with VSL#3 determined a significant improvement in Inflammatory Bowel Disease Questionnaire score, whereas this was not the case with placebo. CONCLUSIONS: Treatment with VSL#3 is effective in the prevention of the onset of acute pouchitis and improves quality of life of patients with ileal pouch-anal anastomosis.  相似文献   
96.
Different antiseptic formulations have shown limitations when applied to disinfecting intact skin, notably short-term tolerability and/or efficacy. The purpose of this study was optimizing a new antiseptic formulation specifically targeted at intact skin disinfection and evaluating its in vitro microbicidal activity and in vivo efficacy. METHODS: The biocidal properties of the antiseptic solution containing 0.5% chloramine-T diluted in 50% isopropyl alcohol (Cloral; Eurospital SpA Trieste, Italy) were measured in vitro versus gram-positive-, gram-negative-, and acid-alcohol-resistant germs and fungi with standard suspension tests in the presence of fetal bovine serum. Virus-inhibiting activity was evaluated in vitro against human cytomegalovirus, herpes simplex virus, poliovirus, hepatitis B virus, and hepatitis C virus. Tests used different methods for the different biologic and in vitro replication capacity of these human viruses. Lastly, Cloral tolerability and skin colonization retardation efficacy after disinfection were studied in vivo. RESULTS: The antiseptic under review showed fast and sustained antimicrobial activity. The efficacy of Cloral against clinically important bacterial and viral pathogens and fungi was highlighted under the experimental conditions described in this article. Finally, microbial regrowth lag and no side effects were documented in vivo after disinfection of 11 volunteers. CONCLUSIONS: A stable chloramine-T solution in isopropyl alcohol may be suggested for intact skin antisepsis.  相似文献   
97.

Introduction

The prediction of ventricular tachyarrhythmias among patients with implantable cardioverter defibrillators is difficult with available clinical tools. We sought to assess whether in patients with heart failure (HF) and reduced ejection fraction with defibrillators, physiological sensor-based HF status, as summarized by the HeartLogic index, could predict appropriate device therapies.

Methods

Five hundred and sixty-eight consecutive HF patients with defibrillators (n = 158, 28%) or cardiac resynchronization therapy-defibrillators (n = 410, 72%) were included in this prospective observational multicenter analysis. The association of both HeartLogic index and its physiological components with defibrillator shocks and overall appropriate therapies was assessed in regression and time-dependent Cox models.

Results

Over a follow-up of 25 (15–35) months, 122 (21%) patients received an appropriate device therapy (shock, n = 74, 13%), while the HeartLogic index crossed the threshold value (alert, HeartLogic ≥ 16) 1200 times (0.71 alerts/patient-year) in 370 (65%) subjects. The occurrence of ≥1 HeartLogic alert was significantly associated with both appropriate shocks (Hazard ratios [HR]: 2.44, 95% confidence interval [CI]: 1.49–3.97, p = .003), and any appropriate defibrillator therapies. In multivariable time-dependent Cox models, weekly IN-alert state was the strongest predictor of appropriate defibrillator shocks (HR: 2.94, 95% CI: 1.73–5.01, p < .001) and overall therapies. Compared with stable patients, patients with appropriate shocks had significantly higher values of HeartLogic index, third heart sound amplitude, and resting heart rate 30–60 days before device therapy.

Conclusion

The HeartLogic index is an independent dynamic predictor of appropriate defibrillator therapies. The combined index and its individual physiological components change before the arrhythmic event occurs.  相似文献   
98.
OBJECTIVES: To test four 16-membered macrolides (josamycin, spiramycin, midecamycin and rokitamycin) along with other compounds in the same class (erythromycin, clarithromycin, roxithromycin and azithromycin) plus clindamycin and telithromycin, against Streptococcus pyogenes and Streptococcus pneumoniae isolates with well-characterized resistance genotypes. METHODS: Four hundred and eighty-six isolates of S. pyogenes and 375 isolates of S. pneumoniae were assayed for their macrolide susceptibilities and investigated by PCR to detect their different erythromycin resistance genes. All strains had been isolated over the period 2002-2003 from specimens of different human origin obtained in 14 different Italian centres. RESULTS: All 16-membered macrolides showed very low MICs (MIC(50)s and MIC(90)s, < or =0.06-0.5 mg/L) for the erythromycin-susceptible isolates and for those with the M phenotype, but the telithromycin MICs for the M-type isolates were at least four times higher (MIC(90)s, 0.5 mg/L). In S. pyogenes, the MIC(50)s of 16-membered macrolides for the cMLS(B) isolates were > or = 256 mg/L, whereas that for telithromycin was 4 mg/L; the MIC(50)s of 16-membered macrolides and telithromycin ranged from < or = 0.06 to 0.5 mg/L for the iMLS(B) isolates with erm(A) and from 0.12 to > or = 256 mg/L for those with erm(B). In S. pneumoniae, the MIC(50)s of the 16-membered macrolides for the cMLS(B) isolates ranged from 0.5 to 128 mg/L, whereas for the iMLS(B) isolates their values ranged from < or = 0.06 to 4 mg/L; the MIC(50)s and MIC(90)s of telithromycin for both the cMLS(B) and the iMLS(B) isolates ranged from < or = 0.06 to 0.12 mg/L. CONCLUSIONS: MICs ranged for all the drugs, except telithromycin, from < or = 0.06 to > or = 256 mg/L, with 15% to 30% resistant S. pyogenes for all drugs tested except clindamycin (8%) and telithromycin (5.4%) and 10% to 40% resistant S. pneumoniae for all drugs tested except telithromycin (0.3%). In both S. pyogenes and S. pneumoniae, erythromycin resistance related to a mef gene meant that telithromycin MICs were definitely higher than in erythromycin-susceptible isolates, although telithromycin susceptibility was preserved in all cases. In S. pyogenes, the activity of both 16-membered macrolides and telithromycin against the iMLS(B) strains proved to be dependent on the erm gene involved, being greater against isolates with erm(A).  相似文献   
99.
This study examined variations in gene expression between FFPE blocks within tumors of individual patients. Microarray data were used to measure tumor heterogeneity within and between patients and disease states. Data were used to determine the number of samples needed to power biomarker discovery studies. Bias and variation in gene expression were assessed at the intrapatient and interpatient levels and between adenocarcinoma and squamous samples. A mixed-model analysis of variance was fitted to gene expression data and model signatures to assess the statistical significance of observed variations within and between samples and disease states. Sample size analysis, adjusted for sample heterogeneity, was used to determine the number of samples required to support biomarker discovery studies. Variation in gene expression was observed between blocks taken from a single patient. However, this variation was considerably less than differences between histological characteristics. This degree of block-to-block variation still permits biomarker discovery using either macrodissected tumors or whole FFPE sections, provided that intratumor heterogeneity is taken into account. Failure to consider intratumor heterogeneity may result in underpowered biomarker studies that may result in either the generation of longer gene signatures or the inability to identify a viable biomarker. Moreover, the results of this study indicate that a single biopsy sample is suitable for applying a biomarker in non-small-cell lung cancer.  相似文献   
100.
This study has investigated, under controlled conditions, peripheral mononuclear cells (PMNC) subset redistribution in a human experimental stress model consisting of cycloergometer activity in healthy male volunteers exposed to a stressful stimulus. After stressful stimuli, leucocyte subpopulations undergo a stereotyped redistribution peculiar for each PMNC cytotype. PMNC subpopulations involved to a greater extent were natural killer (NK) cells and lymphocytes T “memory” cells. The post-stress period was characterized by a decrease of the NK subpopulation. Our findings confirm the view of a sensible functional reduction of immunocompetence in stress conditions. This brings to the opening, even if for a short time, an “immunological window.”. This window remains open throughout the time of the stimulus, probably representing the basis of the progressive reduction of the competency of immune system. Catecholamines support the acute effects of stress influencing the anatomical redistribution of lymphocyte subpopulation and intermediating acute effects on PMNC. Cortisol, acting for longer time, contributes to create and maintain both the neutrocytosis and lymphopenia in the post-stress period following lymphocytosis.  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