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   20046篇
  免费   1389篇
  国内免费   56篇
耳鼻咽喉   125篇
儿科学   427篇
妇产科学   268篇
基础医学   2670篇
口腔科学   324篇
临床医学   2514篇
内科学   3477篇
皮肤病学   198篇
神经病学   1770篇
特种医学   703篇
外科学   2814篇
综合类   220篇
一般理论   28篇
预防医学   2601篇
眼科学   427篇
药学   1589篇
中国医学   35篇
肿瘤学   1301篇
  2023年   123篇
  2022年   76篇
  2021年   431篇
  2020年   308篇
  2019年   435篇
  2018年   511篇
  2017年   390篇
  2016年   429篇
  2015年   580篇
  2014年   741篇
  2013年   968篇
  2012年   1638篇
  2011年   1666篇
  2010年   949篇
  2009年   887篇
  2008年   1457篇
  2007年   1599篇
  2006年   1449篇
  2005年   1446篇
  2004年   1410篇
  2003年   1330篇
  2002年   1149篇
  2001年   138篇
  2000年   106篇
  1999年   155篇
  1998年   192篇
  1997年   130篇
  1996年   96篇
  1995年   96篇
  1994年   105篇
  1993年   85篇
  1992年   46篇
  1991年   42篇
  1990年   28篇
  1989年   32篇
  1988年   22篇
  1987年   30篇
  1986年   24篇
  1985年   23篇
  1984年   23篇
  1983年   25篇
  1982年   22篇
  1981年   25篇
  1980年   20篇
  1979年   4篇
  1978年   9篇
  1977年   7篇
  1976年   13篇
  1975年   3篇
  1961年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Background The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions.Methods This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT)-guided treatment recommendations during the pandemic, designated ‘standard’ or ‘COVID-altered’, in the preoperative, operative and post-operative setting.Findings Of 3776 patients (from 64 UK units) in the study, 2246 (59%) had ‘COVID-altered’ management. ‘Bridging’ endocrine therapy was used (n = 951) where theatre capacity was reduced. There was increasing access to COVID-19 low-risk theatres during the study period (59%). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2–9%) using ‘NHS Predict’. There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1%) tested positive for SARS-CoV-2 during their treatment journey.Conclusions The majority of ‘COVID-altered’ management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic. However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown.Subject terms: Breast cancer, Surgical oncology, Health care economics, Quality of life, Health policy  相似文献   
3.
PURPOSEWe aimed to evaluate the effect on the radiation dose to the patient by reducing the tube current during the placement of the ablation needles (reduced dose group) compared with the patient doses delivered when scanning at the standard fully diagnostic level (full dose group) in computed tomography (CT)-guided percutaneous cryoablation.METHODSWe conducted a retrospective study of 103 patients undergoing cryoablation in a tertiary cancer center. Overall, 62 patients were scanned with standard exposure parameters (full dose group) set on a 64-slice multidetector CT scanner, while 41 patients were scanned on a reduced dose protocol. Dose levels were retrieved from the hospital picture and archiving communication system including the volumetric CT dose index (CTDIvol), total dose length product (DLP), length of cryoablation procedure, number of cryoablation needles and patient size. Wilcoxon Mann-Whitney (rank-sum) tests were used to compare the median DLP, CTDIvol and skin dose between the two groups.RESULTSMedian total DLP for the full dose group was 6025 mGy·cm (1909–13353 mGy·cm) compared with 3391 mGy·cm (1683–6820 mGy·cm) for the reduced dose group. The reduced dose group had a 44% reduction in total DLP and 42% reduction in total CTDIvol (p < 0.001). The estimated skin doses were 384 mGy for the full dose group and 224 mGy for the reduced dose group (42% reduction) (p < 0.001). At 12-month follow-up, the technical success for the full dose (n=62) was 97% with 2 patients requiring a further cryoablation treatment for residual tumor. The technical success for the reduced dose group (n=41) was 100%.CONCLUSIONCT dose reduction technique during image-guided cryoablation treatment of renal tumors can achieve significant radiation dose reduction whilst maintaining sufficient image quality.

Renal cell carcinoma is the most common kidney cancer and has a rising incidence (14), with obesity and smoking being major risk factors (58).Image-guided ablation offers a more minimally invasive option compared with surgery and the current evidence base shows that it is a safe and effective treatment for T1a tumors, with a low rate of complications (911). The major advantage of cryoablation over other modalities is the ability to accurately visualize the iceball and therefore zone of ablation on intraprocedural imaging, either with computed tomography (CT) or magnetic resonance imaging (MRI) (12, 13). However, renal cryoablation involves the placement of more ablation probes and can have almost three times the radiation exposure compared with CT-guided radiofrequency ablation procedures (14).In addition to this substantial radiation dose per cryoablation, estimated to be between 32 and 39.7 mSv, the follow-up CT imaging will also add to the total radiation burden (15, 16). Whilst this level of radiation dose and associated stochastic risk may be a lesser concern in the older patients, greater consideration needs to be given to younger patients (<50 years old) and in patients requiring lifelong follow-up imaging, in particular those with hereditary diseases such as Von Hippel-Lindau syndrome (15). To our knowledge, the potential for reducing radiation dose for cryoablation patients.The principle aim of this study was to evaluate the effect on the radiation dose to the patient by reducing the tube current during the placement of the ablation needles (reduced dose group) compared with the patient doses delivered when scanning at the standard fully diagnostic level (full dose group) in CT-guided percutaneous cryoablation.  相似文献   
4.
Rifamycins (rifampin, rifabutin, and rifapentine) play an essential role in the treatment of mycobacterial and some nonmycobacterial infections. They also induce the activity of various drug transporting and metabolizing enzymes, which can impact the concentrations and efficacy of substrates. Many anticoagulant and antiplatelet (AC/AP) agents are substrates of these enzymes and have narrow therapeutic indices, leading to risks of thrombosis or bleeding when coadministered with rifamycins. The objective of this systematic review was to evaluate the effects on AC/AP pharmacokinetics, laboratory markers, and clinical safety and efficacy of combined use with rifamycins. A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidance was performed. The PubMed, Embase, and Web of Science databases were queried for English-language reports on combination use of rifamycins and AC/AP agents from database inception through August 2021. The 29 studies identified examined warfarin (n = 17), direct oral anticoagulants (DOACs) (n = 8), and antiplatelet agents (n = 4) combined with rifampin (n = 28) or rifabutin (n = 1). Eleven studies were case reports or small case series; 14 reported on pharmacokinetic or laboratory markers in healthy volunteers. Rifampin-warfarin combinations led to reductions in warfarin area under the curve (AUC) of 15%–74%, with variability by warfarin isomer and study. Warfarin dose increases of up to 3–5 times prerifampin doses were required to maintain coagulation parameters in the therapeutic range. DOAC AUCs were decreased by 20%–67%, with variability by individual agent and with rifampin versus rifabutin. The active metabolite of clopidogrel increased substantially with rifampin coadministration, whereas prasugrel was largely unaffected and ticagrelor saw decreases. Our review suggests most combinations of AC/AP agents and rifampin are problematic. Further studies are required to determine whether rifabutin or rifapentine could be safe alternatives for coadministration with AC/AP drugs.  相似文献   
5.
Graefe's Archive for Clinical and Experimental Ophthalmology - Retinal microvascular endothelial dysfunction is thought to be of importance in the development of ocular vascular diseases....  相似文献   
6.

Introduction

The use of risk calculators predicting clinically significant prostate cancer (csCaP) on biopsy reduces unnecessary biopsies and overdiagnosis of indolent disease compared to a Prostate Specific Antigen (PSA) strategy. Updating these tools using more specific outcome measures and contemporary predictors could potentially lead to further reductions. Our objective was to assess clinical impact of the 4 kallikrein (4K) score, the Rotterdam Prostate Cancer Risk Calculator (RPCRC), and the combination of both for predicting csCaP based on the latest International Society of Urological Pathology grading system and cribriform growth pattern.

Materials and methods

Our prospective cohort consisted of 2,872 men from the first screening round in the European Randomized Study of Screening for Prostate Cancer Rotterdam; biopsy indication PSA ≥ 3.0. The predictive performance of the 4Kscore, RPCRC, and the combination of RPCRC with 4Kscore were assessed with area under the receiver operator characteristic curve (AUC) and calibration plots. Decision curve analysis was used to evaluate the reduction of unnecessary biopsy and indolent CaP.

Results

The csCaP was present in 242 (8%) men, and indolent CaP in 578 (20%). The 4Kscore and RPCRC had similar high AUCs (0.88 vs. 0.87; P?=?0.41). The 4Kscore-RPCRC combination improved AUC to 0.89 compared to 4Kscore (P < 0.01) and RPCRC (P < 0.01). The RPCRC and 4Kscore reduced the number of Bx with 42 and 44, respectively, per 100 men at risk compared to a ≥PSA 3.0 strategy without increasing missed csCaP. The RPCRC-4Kscore combination resulted in a slight additional net reduction of 3.3 biopsies per 100 men.

Conclusions

The RPCRC and 4Kscore had similar reductions of unnecessary biopsies and overdiagnosis of indolent disease. Combination of both models slightly reduced unnecessary biopsies further. Gain in net benefit must, however, be weighed against additional costs and availability of tests.  相似文献   
7.
In this first, double-blind, randomized, placebo-controlled exploratory trial, we evaluate the efficacy and safety of incobotulinumtoxinA and feasibility of using kinematic tremor assessment to aid in the planning of muscle selection in a multicenter setting. Reproducibility of the planning technology to other clinical sites was explored. In this trial (NCT02207946), patients with upper-limb essential tremor (ET) were randomized 2:1 to a single treatment cycle of incobotulinumtoxinA or placebo. A tremor kinematic analytics investigational device was used to define a customized muscle set for injection, related to the pattern of the wrist, forearm, elbow, and shoulder tremor for each patient, and the incobotulinumtoxinA dose per muscle (total ≤ 200 U). Fahn–Tolosa–Marin (FTM) Part B motor performance score, Global Impression of Change Scale (GICS), and kinematic analysis-based efficacy evaluations were assessed. Thirty patients were randomized (incobotulinumtoxinA, n = 19; placebo, n = 11). FTM motor performance scores showed greater improvement with incobotulinumtoxinA versus placebo at Week 4 (p = 0.003) and Week 8 (p = 0.031). The physician-rated GICS score indicated improvement with incobotulinumtoxinA versus placebo at Week 4 (p < 0.05). IncobotulinumtoxinA also decreased accelerometric hand-tremor amplitude versus placebo from baseline to Week 4 (p = 0.004) and Week 8 (p < 0.001), with persistent tremor reduction up to 24 weeks post-injection. IncobotulinumtoxinA produced a slight and transient reduction of maximal grip strength versus placebo; two patients reported localized finger muscle weakness. Customized incobotulinumtoxinA injections decreased tremor severity and improved hand motor function in patients with upper-limb ET after a single injection cycle, with a favorable tolerability profile. The study showed that tremor kinematic analytics technology could be successfully scaled for use in other clinical sites.  相似文献   
8.
9.
Journal of Autism and Developmental Disorders - Slower habituation to repeating stimuli characterises Autism, but it is not known whether this is driven by difficulties with information processing...  相似文献   
10.
MALT1 is a key mediator of NF-κB signaling and a main driver of B-cell lymphomas. Remarkably, MALT1 is expressed in the majority of pancreatic ductal adenocarcinomas (PDACs) as well, but absent from normal exocrine pancreatic tissue. Following, MALT1 shows off to be a specific target in cancer cells of PDAC without affecting regular pancreatic cells. Therefore, we studied the impact of pharmacological MALT1 inhibition in pancreatic cancer and showed promising effects on tumor progression. Mepazine (Mep), a phenothiazine derivative, is a known potent MALT1 inhibitor. Newly, we described that biperiden (Bip) is a potent MALT1 inhibitor with even less pharmacological side effects. Thus, Bip is a promising drug leading to reduced proliferation and increased apoptosis in PDAC cells in vitro and in vivo. By compromising MALT1 activity, nuclear translocation of c-Rel is prevented. c-Rel is critical for NF-κB-dependent inhibition of apoptosis. Hence, off-label use of Bip or Mep represents a promising new therapeutic approach to PDAC treatment. Regularly, the Anticholinergicum Bip is used to treat neurological side effects of Phenothiazines, like extrapyramidal symptoms.  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