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   2330125篇
  免费   174907篇
  国内免费   3285篇
耳鼻咽喉   32027篇
儿科学   75669篇
妇产科学   62663篇
基础医学   345259篇
口腔科学   63547篇
临床医学   209683篇
内科学   452335篇
皮肤病学   51687篇
神经病学   183713篇
特种医学   87895篇
外国民族医学   490篇
外科学   352753篇
综合类   47303篇
现状与发展   12篇
一般理论   848篇
预防医学   181121篇
眼科学   54135篇
药学   174502篇
  9篇
中国医学   4411篇
肿瘤学   128255篇
  2019年   19548篇
  2018年   27071篇
  2017年   20358篇
  2016年   22756篇
  2015年   25655篇
  2014年   36116篇
  2013年   53979篇
  2012年   74698篇
  2011年   79431篇
  2010年   47063篇
  2009年   44578篇
  2008年   74624篇
  2007年   79497篇
  2006年   80321篇
  2005年   77795篇
  2004年   74348篇
  2003年   71527篇
  2002年   69204篇
  2001年   108540篇
  2000年   111132篇
  1999年   92844篇
  1998年   25351篇
  1997年   21966篇
  1996年   22355篇
  1995年   22560篇
  1994年   20763篇
  1993年   19593篇
  1992年   71871篇
  1991年   70045篇
  1990年   68347篇
  1989年   65625篇
  1988年   60245篇
  1987年   59075篇
  1986年   55182篇
  1985年   52966篇
  1984年   39235篇
  1983年   33300篇
  1982年   19758篇
  1981年   17767篇
  1979年   35782篇
  1978年   25578篇
  1977年   21130篇
  1976年   20254篇
  1975年   21752篇
  1974年   26089篇
  1973年   24764篇
  1972年   23179篇
  1971年   22013篇
  1970年   20220篇
  1969年   19285篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Virtual reality is a form of high-fidelity simulation that may be used to enhance the quality of medical education. We created a bespoke virtual reality trainer software using high resolution motion capture and ultrasound imagery to teach cognitive-motor needling skills necessary for the performance of ultrasound-guided regional anaesthesia. The primary objective of this study was to determine the construct validity between novice and experienced regional anaesthetists. Secondary objectives were: to create learning curves for needling performance; compare the virtual environment immersion with other high-fidelity virtual reality software; and compare cognitive task loads imposed by the virtual trainer compared with real-life medical procedures. We recruited 21 novice and 15 experienced participants, each of whom performed 40 needling attempts on four different virtual nerve targets. Performance scores for each attempt were calculated based on measured metrics (needle angulation, withdrawals, time taken) and compared between the groups. The degree of virtual reality immersion was measured using the Presence Questionnaire, and cognitive burden was measured using the NASA-Task Load Index. Scores by experienced participants were significantly higher than novices (p = 0.002) and for each nerve target (84% vs. 77%, p = 0.002; 86% vs. 79%, p = 0.003; 87% vs. 81%, p = 0.002; 87% vs. 80%, p = 0.003). Log–log transformed learning curves demonstrated individual variability in performance over time. The virtual reality trainer was rated as being comparably immersive to other high-fidelity virtual reality software in the realism, possibility to act and quality of interface subscales (all p > 0.06) but not in the possibility to examine and self-performance subscales (all p < 0.009). The virtual reality trainer created workloads similar to those reported in real-life procedural medicine (p = 0.53). This study achieved initial validation of our new virtual reality trainer and allows progression to a planned definitive trial that will compare the effectiveness of virtual reality training on real-life regional anaesthesia performance.  相似文献   
72.
Niedmers  H.  Defosse  J. M.  Wappler  F.  Lopez  A.  Schieren  M. 《Der Anaesthesist》2022,71(8):608-617
Die Anaesthesiologie - Während zahlreiche Kliniken in Deutschland thoraxchirurgische Eingriffe durchführen, liegen bisher nur unzureichende Daten über die verwendeten...  相似文献   
73.
Gestational trophoblastic neoplasia (GTN) patients are treated according to the eight-variable International Federation of Gynaecology and Obstetrics (FIGO) scoring system, that aims to predict first-line single-agent chemotherapy resistance. FIGO is imperfect with one-third of low-risk patients developing disease resistance to first-line single-agent chemotherapy. We aimed to generate simplified models that improve upon FIGO. Logistic regression (LR) and multilayer perceptron (MLP) modelling (n = 4191) generated six models (M1-6). M1, all eight FIGO variables (scored data); M2, all eight FIGO variables (scored and raw data); M3, nonimaging variables (scored data); M4, nonimaging variables (scored and raw data); M5, imaging variables (scored data); and M6, pretreatment hCG (raw data) + imaging variables (scored data). Performance was compared to FIGO using true and false positive rates, positive and negative predictive values, diagnostic odds ratio, receiver operating characteristic (ROC) curves, Bland-Altman calibration plots, decision curve analysis and contingency tables. M1-6 were calibrated and outperformed FIGO on true positive rate and positive predictive value. Using LR and MLP, M1, M2 and M4 generated small improvements to the ROC curve and decision curve analysis. M3, M5 and M6 matched FIGO or performed less well. Compared to FIGO, most (excluding LR M4 and MLP M5) had significant discordance in patient classification (McNemar's test P < .05); 55-112 undertreated, 46-206 overtreated. Statistical modelling yielded only small gains over FIGO performance, arising through recategorisation of treatment-resistant patients, with a significant proportion of under/overtreatment as the available data have been used a priori to allocate primary chemotherapy. Streamlining FIGO should now be the focus.  相似文献   
74.
Modified-release opioids are often prescribed for the management of moderate to severe acute pain following total hip and knee arthroplasty, despite recommendations against their use due to increasing concerns regarding harm. The primary objective of this multicentre study was to examine the impact of modified-release opioid use on the incidence of opioid-related adverse events compared with immediate-release opioid use, among adult inpatients following total hip or knee arthroplasty. Data for total hip and knee arthroplasty inpatients receiving an opioid analgesic for postoperative analgesia during hospitalisation were collected from electronic medical records of three tertiary metropolitan hospitals in Australia. The primary outcome was the incidence of opioid-related adverse events during hospital admission. Patients who received modified with or without immediate-release opioids were matched to those receiving immediate-release opioids only (1:1) using nearest neighbour propensity score matching with patient and clinical characteristics as covariates. This included total opioid dose received. In the matched cohorts, patients given modified-release opioids (n = 347) experienced a higher incidence of opioid-related adverse events overall, compared with those given immediate-release opioids only (20.5%, 71/347 vs. 12.7%, 44/347; difference in proportions 7.8% [95%CI 2.3–13.3%]). Modified-release opioid use was associated with an increased risk of harm when used for acute pain during hospitalisation after total hip or knee arthroplasty.  相似文献   
75.
BackgroundThe purpose of this study is to evaluate the effect of body mass index (BMI) on discharge to a postacute care (PAC) facility following elective total shoulder arthroplasty (TSA).MethodsThe National Surgical Quality Improvement Program database was queried to identify adult patients (>18 years old) who underwent inpatient TSA for primary osteoarthritis between 2005 and 2018. Hemiarthroplasty, revision TSA, trauma indications, and outpatient procedures were excluded. Patient and perioperative data were identified. Univariate analysis and multivariate logistic regression were used to assess the relationship between BMI and discharge to PAC facilities.ResultsA total of 10,198 patients with a primary TSA were identified. The majority (93%) of patients were discharged home vs. 7% to PAC facilities. Patients discharged to PAC had significantly higher mean BMI (P = .006). After controlling for demographic and comorbid factors, BMI was the only modifiable risk factor that was independently associated with an increased risk of discharge to a PAC. For every increase in BMI point, there was an increased risk of discharge to a PAC by 2.9% (odds ratio [OR] 1.029, confidence interval [CI] 1.016-1.041, P < .001). Additional covariates associated with PAC discharge were older age (OR 1.113, CI 1.099-1.127, P < .001), female gender (OR 3.037, CI 2.489-3.705, P < .001), and dependent functional status (OR 8.322, CI 5.544-12.492, P < .001).ConclusionMost patients undergoing TSA were discharged home following surgery. While age, sex, and functional status also affect disposition, elevated BMI is the only modifiable risk factor that independently predicts PAC discharge. Consideration of patient BMI prior to elective TSA may greatly improve discharge planning and management of patient expectations.  相似文献   
76.

Background

Limited data exist on the clinical behavior of pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) with distant metastases at onset, and a clear standard of care has not yet been defined.

Methods

This cohort study reports on pediatric adult-type metastatic NRSTS enrolled in two concurrent prospective European studies, i.e., the randomized BERNIE study and the single-arm MTS 2008 study developed by the European paediatric Soft tissue sarcoma Study Group. Treatment programs were originally designed for patients with metastatic rhabdomyosarcoma, i.e., nine courses of multidrug chemotherapy (with or without bevacizumab in the BERNIE study), followed by 12 cycles of maintenance therapy, whereas radiotherapy and/or surgery (on primary tumor and/or metastases) were delayed until after seven courses of chemotherapy had been administered.

Results

The study included 61 patients <21 years old treated from July 2008 to December 2016. The lung was the site of metastases in 75% of the cases. All patients received multi-agent chemotherapy, 44% had local therapy to primary tumor, and 18% had treatment of metastases. Median time to progression/relapse was 6 months. A high rate of tumor progression was observed during the initial part of the chemotherapy program. With a median follow-up of 41.5 months (range, 2–111 months), 3-year event-free survival and overall survival were 15.4% (95% confidence interval [CI], 7.6–25.7) and 34.9% (95% CI, 22.7–47.5), respectively. There were no statistically significant differences in outcome depending on the type of treatment administered.

Conclusions

The study confirmed the overall poor outcome for patients with metastatic NRSTS, whose treatment remains a challenge.

Plain Language Summary

  • Pediatric non-rhabdomyosarcoma soft tissue sarcomas form a heterogeneous group of rare tumors.
  • Although recent international studies have defined the standard of care for patients with localized disease, limited data are available on the clinical behavior of patients with distant metastases.
  • This study on 61 metastatic cases treated on two prospective European protocols confirms that the chances of survival of such patients are often dismal and a standard treatment is still lacking.
  相似文献   
77.
International recommendations encourage liberal administration of oxygen to patients having surgery under general anaesthesia, ostensibly to reduce surgical site infection. However, the optimal oxygen regimen to minimise postoperative complications and enhance recovery from surgery remains uncertain. The hospital operating theatre randomised oxygen (HOT-ROX) trial is a multicentre, patient- and assessor-blinded, parallel-group, randomised clinical trial designed to assess the effect of a restricted, standard care, or liberal peri-operative oxygen therapy regimen on days alive and at home after surgery in adults undergoing prolonged non-cardiac surgery under general anaesthesia. Here, we report the findings of the internal vanguard feasibility phase of the trial undertaken in four large metropolitan hospitals in Australia and New Zealand that included the first 210 patients of a planned overall 2640 trial sample, with eight pre-specified endpoints evaluating protocol implementation and safety. We screened a total of 956 participants between 1 September 2019 and 26 January 2021, with data from 210 participants included in the analysis. Median (IQR [range]) time-weighted average intra-operative FiO2 was 0.30 (0.26–0.35 [0.20–0.59]) and 0.47 (0.44–0.51 [0.37–0.68]) for restricted and standard care, respectively (mean difference (95%CI) 0.17 (0.14–0.20), p < 0.001). Median time-weighted average intra-operative FiO2 was 0.83 (0.80–0.85 [0.70–0.91]) for liberal oxygen therapy (mean difference (95%CI) compared with standard care 0.36 (0.33–0.39), p < 0.001). All feasibility endpoints were met. There were no significant patient adverse events. These data support the feasibility of proceeding with the HOT-ROX trial without major protocol modifications.  相似文献   
78.
Detailed contemporary knowledge of the characteristics of the surgical population, national anaesthetic workload, anaesthetic techniques and behaviours are essential to monitor productivity, inform policy and direct research themes. Every 3–4 years, the Royal College of Anaesthetists, as part of its National Audit Projects (NAP), performs a snapshot activity survey in all UK hospitals delivering anaesthesia, collecting patient-level encounter data from all cases under the care of an anaesthetist. During November 2021, as part of NAP7, anaesthetists recorded details of all cases undertaken over 4 days at their site through an online survey capturing anonymous patient characteristics and anaesthetic details. Of 416 hospital sites invited to participate, 352 (85%) completed the activity survey. From these, 24,177 reports were returned, of which 24,172 (99%) were included in the final dataset. The work patterns by day of the week, time of day and surgical specialty were similar to previous NAP activity surveys. However, in non-obstetric patients, between NAP5 (2013) and NAP7 (2021) activity surveys, the estimated median age of patients increased by 2.3 years from median (IQR) of 50.5 (28.4–69.1) to 52.8 (32.1–69.2) years. The median (IQR) BMI increased from 24.9 (21.5–29.5) to 26.7 (22.3–31.7) kg.m–2. The proportion of patients who scored as ASA physical status 1 decreased from 37% in NAP5 to 24% in NAP7. The use of total intravenous anaesthesia increased from 8% of general anaesthesia cases to 26% between NAP5 and NAP7. Some changes may reflect the impact of the COVID-19 pandemic on the anaesthetic population, though patients with confirmed COVID-19 accounted for only 149 (1%) cases. These data show a rising burden of age, obesity and comorbidity in patients requiring anaesthesia care, likely to impact UK peri-operative services significantly.  相似文献   
79.
Postbariatric loss of muscle tissue could negatively affect long-term health due to its role in various bodily processes, such as metabolism and functional capacity. This meta-analysis aimed to unravel time-dependent changes in the magnitude and progress of lean body mass (LBM), fat-free mass (FFM), and skeletal muscle mass (SMM) loss following bariatric surgery. A systematic literature search was conducted in Pubmed, Embase, and Web of Science. Fifty-nine studies assessed LBM (n = 37), FFM (n = 20), or SMM (n = 3) preoperatively and ≥1 time points postsurgery. Random-effects meta-analyses were performed to determine pooled loss per outcome parameter and follow-up time point. At 12-month postsurgery, pooled LBM loss was ?8.13 kg [95%CI ?9.01; ?7.26]. FFM loss and SMM loss were ?8.23 kg [95%CI ?10.74; ?5.73] and ?3.18 kg [95%CI ?5.64; ?0.71], respectively. About 55% of 12-month LBM loss occurred within 3-month postsurgery, followed by a more gradual decrease up to 12 months. Similar patterns were seen for FFM and SMM. In conclusion, >8 kg of LBM and FFM loss was observed within 1-year postsurgery. LBM, FFM, and SMM were predominantly lost within 3-month postsurgery, highlighting that interventions to mitigate such losses should be implemented perioperatively.  相似文献   
80.
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