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   1675篇
  免费   129篇
  国内免费   11篇
耳鼻咽喉   7篇
儿科学   45篇
妇产科学   60篇
基础医学   233篇
口腔科学   39篇
临床医学   178篇
内科学   324篇
皮肤病学   36篇
神经病学   126篇
特种医学   44篇
外科学   263篇
综合类   38篇
预防医学   126篇
眼科学   73篇
药学   140篇
中国医学   16篇
肿瘤学   67篇
  2024年   5篇
  2023年   43篇
  2022年   54篇
  2021年   93篇
  2020年   68篇
  2019年   89篇
  2018年   108篇
  2017年   78篇
  2016年   92篇
  2015年   83篇
  2014年   105篇
  2013年   117篇
  2012年   165篇
  2011年   156篇
  2010年   88篇
  2009年   59篇
  2008年   80篇
  2007年   77篇
  2006年   70篇
  2005年   44篇
  2004年   35篇
  2003年   22篇
  2002年   14篇
  2001年   10篇
  2000年   3篇
  1999年   15篇
  1998年   5篇
  1997年   4篇
  1996年   3篇
  1995年   2篇
  1993年   1篇
  1992年   4篇
  1991年   4篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1979年   1篇
  1969年   1篇
  1968年   1篇
排序方式: 共有1815条查询结果,搜索用时 15 毫秒
91.
BackgroundTo provide information about pathogens’ coinfection prevalence with SARS‐CoV‐2 could be a real help to save patients’ lives. This study aims to evaluate the pathogens’ coinfection prevalence among COVID‐19 patients.MethodIn order to find all of the relevant articles, we used systematic search approach. Research‐based databases including PubMed, Web of Science, Embase, and Scopus, without language restrictions, were searched to identify the relevant bacterial, fungal, and viral coinfections among COVID‐19 cases from December 1, 2019, to August 23, 2021. In order to dig deeper, other scientific repositories such as Medrxiv were probed.ResultsA total of 13,023 studies were found through systematic search. After thorough analysis, only 64 studies with 61,547 patients were included in the study. The most common causative agents of coinfection among COVID‐19 patients were bacteria (pooled prevalence: 20.97%; 95% CI: 15.95–26.46; I 2: 99.9%) and less frequent were virus coinfections (pooled prevalence: 12.58%; 95% CI: 7.31–18.96; I 2: 98.7%). The pooled prevalence of fungal coinfections was also 12.60% (95% CI: 7.84–17.36; I 2: 98.3%). Meta‐regression analysis showed that the age sample size and WHO geographic region did not influenced heterogeneity.ConclusionWe identified a high prevalence of pathogenic microorganism coinfection among COVID‐19 patients. Because of this rate of coinfection empirical use of antibacterial, antifungal, and antiviral treatment are advisable specifically at the early stage of COVID‐19 infection. We also suggest running simultaneously diagnostic tests to identify other microbiological agents’ coinfection with SARS‐CoV‐2.  相似文献   
92.
Objective: To identify the incidence rate, relative risk, hotspot regions and incidence trend of COVID-19 in Qom province, northwest part of Iran in the first s...  相似文献   
93.
94.
In early 1994, a novel strain of Mycoplasma gallisepticum (MG)--a poultry pathogen with a world-wide distribution--emerged in wild house finches and within 3 years had reached epidemic proportions across their eastern North American range. The ensuing epizootic resulted in a rapid decline of the host population coupled with considerable seasonal fluctuations in prevalence. To understand the dynamics of this disease system, a multi-disciplinary team composed of biologists, veterinarians, microbiologists and mathematical modelers set forth to determine factors driving and influenced by this host-pathogen system. On a broad geographic scale, volunteer observers ("citizen scientists") collected and reported data used for calculating both host abundance and disease prevalence. The scale at which this monitoring initiative was conducted is unprecedented and it has been an invaluable source of data for researchers at the Cornell Laboratory of Ornithology to track the spread and magnitude of disease both spatially and temporally. At a finer scale, localized and intensive field studies provided data used to quantify the effects of disease on host demographic parameters via capture-mark-recapture modeling, effects of host behavior on disease and vice-versa, and the biological and genetic profiles of birds with known phenotypic characteristics. To balance the field-based component of the study, experiments were conducted with finches held in captivity to describe and quantify the effects of experimental infections on hosts in both individual and social settings. The confluence of these various elements of the investigation provided the foundation for construction of a general compartmentalized epidemiological model of the dynamics of the house finch-MG system. This paper serves several purposes including (i) a basic review of the pathogen, host, and epidemic cycle; (ii) an explanation of our research strategy; (iii) a basic review of results from the diverse multi-disciplinary approaches employed; and (iv) pertinent questions relevant to this and other wildlife disease studies that require further investigation.  相似文献   
95.
Restenosis remains the major limitation of coronary stent implantation, especially in diffuse forms of in-stent restenosis. In this study, rotablation (RA) with adjunct angioplasty of in-stent restenosis was performed in 84 patients. Clinical follow-up and control angiography were obtained 6-month postprocedure. The rate of recurrent restenosis after rotablation for in-stent restenosis at 6-month angiographic follow-up was 45%, resulting in a rate of major adverse cardiac events of 35%. At 3-year follow-up, the cumulative event-free survival rate was 57% for the entire population. The only predictor of MACE at 3-year clinical follow-up by multivariate logistic regression analysis was in-stent lesion length. RA for the treatment of diffuse in-stent restenosis is thereby characterized by high procedural success rates and recurrent angiographic restenosis in 45% of patients with diffuse lesions. Major adverse cardiac events occur most likely within the first 6 months postprocedure. Three years after rotablation of in-stent restenosis, 43% of patients had experienced at least one major adverse cardiac event. Cathet Cardiovasc Intervent 2001;53:334-340.  相似文献   
96.
97.
Objectives: To test the reliability and validity of six aesthetic parameters and to compare the professional‐ and patient‐reported aesthetic outcomes. Material and methods: Thirty‐four patients with 66 implant‐supported premolar crowns were included. Two prosthodontists and 11 dental students evaluated six aesthetic parameters, the Copenhagen Index Score (CIS): (i) crown morphology score, (ii) crown colour match score, (iii) symmetry/harmony score, (iv) mucosal discolouration score, (v) papilla index score, mesially and (vi) papilla index score, distally. The intra‐ and inter‐observer agreement and the internal consistency were analysed by Cohen's κ and Cronbach's α, respectively. The validity of CIS parameters was tested against the corresponding Visual Analogue Scales (VAS) scores. The Spearman correlation coefficients were used. Six aesthetic Oral Health Impact Profile (OHIP) questions were correlated to the CIS and the overall VAS scores. Results: The intra‐observer agreement was >70% in 2/3 and >50% in all observations. The inter‐observed agreement was >50% in 4/5 of all observations. The mucosal discolouration score had the overall highest observed agreement followed by the papilla index scores. The crown morphology and the symmetry/harmony scores had the overall lowest agreement. The Cronbach α value was over 0.8 for all observers. All CIS scores demonstrated significant (P<0.0001) correlation to the corresponding VAS scores. Low correlation coefficients (CIS/OHIP: rs<0.36; VAS/OHIP: rs >?0,24) were found between patient and professional evaluations. Conclusions: The feasibility, reliability and validity of the CIS make the parameters useful for quality control of implant‐supported restorations. The professional‐ and patient‐reported aesthetic outcomes had no significant correlation. To cite this article:
Hosseini M, Gotfredsen K. A feasible, aesthetic quality evaluation of implant‐supported single crowns: an analysis of validity and reliability.
Clin. Oral Impl. Res. 23 , 2012 453–458.
doi: 10.1111/j.1600‐0501.2011.02162.x  相似文献   
98.

Background

Although open radical cystectomy (ORC) remains the gold standard of care for muscle-invasive bladder cancer, robot-assisted radical cystectomy (RARC) continues to gain wider acceptance. In this article, we focus on the steps of RARC, describing our approach, which has been developed over the past 10 yr. Totally intracorporeal RARC aims to offer the benefits of a complete minimally invasive approach while replicating the oncologic outcomes of open surgery.

Objective

We report our outcomes of a totally intracorporeal RARC procedure, describing step by step our technique and highlighting the variations on this standard template of nerve-sparing and female organ–preserving approaches in men and women.

Design, setting, and participants

Between December 2003 and October 2012, a total of 113 patients (94 male and 19 female) underwent totally intracorporeal RARC.

Surgical procedure

We performed RARC, extended pelvic lymph node dissection, and a totally intracorporeal urinary diversion (UD) in all patients. In the accompanying video, we focus on the standard template for RARC, also describing nerve-sparing and female organ–preserving approaches.

Outcome measurements and statistical analysis

Complications and oncologic outcomes are reported, including overall survival (OS) and cancer-specific survival (CSS) using Kaplan-Meier analysis.

Results and limitations

RARC with intracorporeal UD was performed in 113 patients. Mean age was 64 yr (range: 37–84). Forty-three patients underwent intracorporeal ileal conduit, and 70 had intracorporeal neobladder. On surgical pathology, 48% of patients had ≤pT1 disease, 27% had pT2 disease, 13% had pT3 disease, and 12% had pT4 disease. The mean number of lymph nodes removed was 21 (range: 0–57). Twenty percent of patients had lymph node–positive disease. Positive surgical margins occurred in six cases (5.3%). Median follow-up was 25 mo (range: 3–107). We recorded a total of 70 early complications (0–30 d) in 54 patients (47.8%), with 37 patients (32.7%) having Clavien grade ≥3. Thirty-six late complications (>30 d) were recorded in 30 patients (26.5%), with 20 patients (17.7%) having Clavien grade ≥3. One patient (0.9%) died within 90 days of operation from pulmonary embolism. Using Kaplan-Meier analysis, CSS was 81% at 3 yr and 67% at 5 yr.

Conclusions

Our structured approach to RARC has enabled us to develop this complex service while maintaining patient outcomes and complication rates comparable with ORC series. Our results demonstrate acceptable oncologic outcomes and encouraging long-term CSS rates.  相似文献   
99.
OBJECTIVE: The purpose of the present study was to assess the impact of Mg + Zn, Vitamins C + E, and combination of these micronutrients on serum lipid and lipoprotein profiles in type 2 diabetic patients. MATERIALS AND METHODS: In a randomized, double-blind, placebo controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for 3 months; group M: 200 mg Mg and 30 mg Zn (n = 16), group V: 200mg Vitamin C and 150 mg Vitamin E (n = 18), group MV: minerals plus vitamins (n = 17), group P: placebo (n = 18). Fasting blood and urine samples were collected at the beginning and at the end of the trial. Serum triglyceride, total cholesterol, high density lipoprotein cholesterol (HDL-c) and low density lipoprotein cholesterol (LDL-c) were measured enzymatically. Apolipoproteins (apo) A1 and B were measured by immunoturbidimetric method. Adjustment for differences in baselines covariates and changes in variables during study were performed by analysis of covariance using general linear models. RESULTS: Results indicate that after 3 months of supplementation mean serum levels of HDL-c and apo A1 increased significantly in the MV group by 24% (50.4 +/-19.3 mg/dl versus 40.6 +/- 10.8 mg/dl) and 8.8% (169.8 +/- 33.8 mg/dl versus 156.1+ /- 23.9 mg/dl), respectively (P < 0.01). There were no significant changes in the levels of these parameters in the other three groups. Serum levels of total cholesterol, LDL-c, triglyceride, and apo B were not altered after supplementation in all four groups. CONCLUSION: It is concluded that since co-supplementation of Mg, Zn, Vitamins C and E significantly increases HDL-c and apo A1, supplementation of these micronutrients could be recommended for the type 2 diabetic patients based on their daily requirements.  相似文献   
100.
In this work, m-toluidine is electropolymerized at the surface of carbon paste electrode using consecutive cyclic voltammetry in 20 mM monomer aqueous solution in the presence of 6 mM cetyltrimethyl ammonium bromide (CTAB) as surfactant. Then transition metal of nickel is incorporated into the polymer by electrodepositing of Ni (II) from 1.5 M NiSO4 acidic solution using chronoamperometry technique (−1.0 V versus Ag|AgCl|KCl (3 M) for 15 min). In alkaline medium (i.e. NaOH 0.1 M) a good redox behavior of Ni (III)/Ni (II) couple at the surface of Ni/poly (m-toluidine) modified carbon paste electrode (Ni/PMT/MCPE) in the absence and presence of CTAB (Ni/CTAB-PMT/MCPE) can be observed. Electrocatalytic oxidation of methanol has been studied on Ni/PMT/MCPE and Ni/CTAB-PMT/MCPE. The results show that CTAB significantly enhances the catalytic efficiency of nickel particles on the oxidation of methanol in aqueous alkaline media. Moreover, the effects of various parameters such as concentration of CTAB, concentration of methanol, electrodepositing time, film thickness and monomer concentration on the electrooxidation of methanol as well as long-term stability of the Ni/CTAB-PMT/MCPE have also been investigated. This polymeric modified electrode can oxidize the methanol with high current density (over 40 mA cm−2).  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