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   3287篇
  免费   289篇
  国内免费   38篇
耳鼻咽喉   11篇
儿科学   22篇
妇产科学   12篇
基础医学   134篇
口腔科学   23篇
临床医学   133篇
内科学   232篇
皮肤病学   10篇
神经病学   93篇
特种医学   459篇
外科学   100篇
综合类   286篇
预防医学   447篇
眼科学   5篇
药学   751篇
  1篇
中国医学   117篇
肿瘤学   778篇
  2024年   3篇
  2023年   44篇
  2022年   72篇
  2021年   157篇
  2020年   161篇
  2019年   141篇
  2018年   140篇
  2017年   125篇
  2016年   94篇
  2015年   96篇
  2014年   258篇
  2013年   232篇
  2012年   189篇
  2011年   206篇
  2010年   148篇
  2009年   177篇
  2008年   141篇
  2007年   125篇
  2006年   126篇
  2005年   91篇
  2004年   86篇
  2003年   77篇
  2002年   74篇
  2001年   72篇
  2000年   49篇
  1999年   69篇
  1998年   33篇
  1997年   31篇
  1996年   32篇
  1995年   34篇
  1994年   28篇
  1993年   16篇
  1992年   21篇
  1991年   19篇
  1990年   22篇
  1989年   17篇
  1988年   17篇
  1987年   12篇
  1986年   13篇
  1985年   33篇
  1984年   21篇
  1983年   24篇
  1982年   20篇
  1981年   11篇
  1980年   16篇
  1979年   15篇
  1977年   5篇
  1976年   5篇
  1974年   3篇
  1970年   3篇
排序方式: 共有3614条查询结果,搜索用时 15 毫秒
1.
目的:分析《伤寒杂病论》中厚朴的量效关系及配伍用药规律,以更好地指导临床。方法:总结归纳《伤寒杂病论》中含有厚朴的条文,采用SPSS 23.0统计软件分析厚朴剂量与相关因素之间的关系。结果:符合筛选条件含厚朴方剂共11首,占全书总方剂数的9.73%。二元相关性分析显示,厚朴单次用量与药味数、用水量、与剩余水量、单次服用水量和服用次数无明显相关性(P>0.05)。单因素逻辑回归分析显示,厚朴是否为主药与厚朴单次用量、用水量有相关性(P<0.05)结论:厚朴以配伍用药为主,未单独使用,多应用在阳明经证,从量效关系发现,厚朴是否为主药与厚朴单次用量、用水量有相关性。厚朴对于虚实类疾病通过配伍均可达到治疗效果,从药物作用气机的升降浮沉角度,厚朴在体内作用以降为主。厚朴小剂量使用,配伍麻黄、杏仁、生姜、桂枝等可治疗呼吸系统疾病,大剂量配伍半夏、人参、生姜、枳实等可治疗消化系统疾病。  相似文献   
2.
IntroductionSelective internal radiation therapy (SIRT) is a potential treatment of primary renal cell carcinoma (RCC) deemed unsuitable for conventional therapy. RESIRT is the first-in-human study to evaluate safety and feasibility of SIRT for primary RCC.Patients and MethodsPatients with RCC, unsuitable for, or who declined conventional therapy, were eligible. A single transfemoral micro-catheter administration of yttrium-90 (Y-90) resin microspheres (SIR-Spheres) was delivered super selectively via the renal artery to the tumour at intended radiation doses of 75, 100, 150, 200, 300 Gy and a final cohort with a procedural endpoint of “imminent stasis,” in a dose-escalation design. Post-SIRT follow-up was 12 months. Study endpoints included safety and toxicity 30-days and 12-months post-SIRT and tumour response (RECIST v1.1).ResultsIn total, 21 patients were enrolled, mean (SD) age was 75 (9.3) years, WHO performance status was 0 in 81%, 12 (57%) had stage 3 chronic kidney disease, and 7 (33%) had prior contralateral nephrectomy. Overall, 71% of patients completed 12 months of follow-up. Intended doses were delivered without any dose-limiting toxicity. Seventeen out of 21 (81%) patients experienced an adverse event (AE) from any cause within 30 days post-SIRT; all SIRT-related AEs were grade 1 to 2. Best overall tumour responses were partial response 1/21 (4.8%), stable disease 19/21 (90.5%) and progressive disease 1/21 (4.8%).ConclusionThis study demonstrated good tolerability of SIRT at all dose levels including “imminent stasis” in treating primary tumours in RCC patients otherwise unsuitable for conventional therapy. SIRT with Y-90 resin microspheres may be a feasible treatment option for RCC.  相似文献   
3.
目的 探讨调强放疗和多模态影像指导下,鼻咽癌中上颈临床靶区(CTV)剂量优化对保护喉咽、前环和后环的意义。方法 回顾性分析2016—2018年间江苏省肿瘤医院收治的 298例初治鼻咽癌患者资料。所有患者按以下方案进行个体化中上颈CTV剂量优化:A组:双侧完全优化,即双颈CTV剂量均50.4Gy;B组:单侧完全优化,即单侧CTV剂量50.4Gy、对侧60Gy;C组:双侧不完全优化,即双侧CTV剂量均50.4Gy,可疑阳性淋巴结选择性同步推量至60Gy;D组:单侧不完全优化,即单侧CTV剂量50.4Gy,其中可疑阳性淋巴结选择性同步推量至60Gy,对侧60Gy;E组:未优化,即双侧CTV剂量均60Gy。结果 298例患者中 215例行颈部CTV剂量优化,83例未行剂量优化。优化方案中A组 114例、B组 36例、C组 60例、D组 5例。随访时间 6.0~46.3个月,中位随访期28.5个月。全组总生存率为95.6%,无进展生存率为84.2%,颈部区域控制率为98.0%。6例颈部淋巴结复发,其中咽后外侧淋巴结复发 1例,Ⅱ区复发 4例,Ⅲ区复发 0例,Ⅳ区复发 1例。A、B、C、D与E组间喉咽平均剂量比较,P值分别为<0.001、0.016、0.001、0.572;前环平均剂量差异比较,P值分别为<0.001、0.011、<0.001、0.805;后环平均剂量差异比较,P值分别为<0.001、0.004、<0.001、0.252。结论 在多模态影像指导下,结合鼻咽癌颈部淋巴结转移规律进行中上颈CTV剂量优化是安全的,可明显降低喉咽、前环和后环的剂量,从而为中上颈部CTV降量提供依据。  相似文献   
4.
目的针对急性冠脉综合征(ACS)患者经皮冠状动脉介入治疗(PCI)后标准剂量替格瑞洛治疗不耐受(表现为非严重出血或呼吸困难),探讨减半剂量治疗的有效性及安全性。方法纳入使用标准剂量替格瑞洛(90 mg,2/d)不耐受的PCI后ACS患者70例,予以半量替格瑞洛(45 mg,2/d)治疗至PCI后12个月。检测应用半量替格瑞洛治疗前后的血小板聚集功能,记录呼吸困难、出血事件的发生情况及12个月主要不良心血管事件(MACE)的发生情况。结果减半剂量治疗后,二磷酸腺苷(ADP)诱导的血小板聚集率有所升高[(10.0±9.5)%vs.(16.6±10.0)%,P<0.05];呼吸困难明显缓解(共23例,其中显效10例,好转10例,无效2例),总缓解率达87.0%;出血事件明显减少(82.9%vs.24.3%,P<0.05);未记录到MACE。结论PCI后ACS患者予标准剂量替格瑞洛治疗不耐受时,减半剂量治疗可有效缓解呼吸困难和减少出血事件的发生,而未增加MACE的发生率。  相似文献   
5.
Oral methadone may be prescribed to detainees with the aim of minimising the risk of fatal opioid poisoning on release. To study the circumstances under which methadone-related deaths can occur in detention, we audited reports of 17 [14 male, 3 female; median (range) age 34 (22–52) years] such deaths, July 2010–December 2011. The median (range) methadone dose was 40 (10–110) mg/d (N = 16). The median (range) post-mortem blood methadone concentration was 0.42 (0.16–1.40) mg/L. Those who died within 7 days of the commencement of methadone treatment were significantly younger (Mann-Whitney U 102.5, p < 0.05), were prescribed a significantly lower dose (U = 80.0, p < 0.05) and had significantly lower blood methadone concentrations at death (U = 106.5, p < 0.02) than in those given methadone long-term. In 8 reports the prisoner had been recorded as either ‘sleepy’ (N = 7), or ‘unwell’ in the hours before death. In 13 deaths, the prisoner was either found dead first thing in the morning, or in one instance could not be roused (‘snoring heavily’). Pneumonia, tracheobronchitis, end-stage cirrhosis, and ischaemic heart disease/coronary artery atherosclerosis were cited as associated factors in four patients, all of whom were on long term stable methadone treatment. Attention to warning signs of likely methadone toxicity (daytime or excessive drowsiness, snoring, nausea/vomiting) and associated risk factors (use of drugs such as benzodiazepines and gabapentinoids, the presence of respiratory infection, liver or renal disease) could help minimise the risk of unexpected death in patients given methadone.  相似文献   
6.
ObjectiveTo explore the effects and dose–response relationship of Tai Chi for type 2 diabetes mellitus (T2DM) and to evaluate the methodological quality of the included trials and evidence quality of the outcomes.MethodsNine major English and Chinese databases were searched for randomized controlled trials of Tai Chi for T2DM from inception to December 2021. The effects and dose–response relationships were assessed with a meta-analysis and meta-regression using Stata.16. The methodological quality of the included studies was assessed using the risk of bias tool. The evidence quality of the outcomes was assessed using the GRADE tool.ResultsA total of 24 studies with 1314 patients were included. Compared with the usual care, Tai Chi improved HbA1c (MD = ?0.80%, 95% CI [?1.05, ?0.54], P < .001, I2 = 18.29%, very low–quality evidence), FBG (SMD = ?0.58, 95% CI [?0.86, ?0.31], P < .001, I2 = 53.2%, low-quality evidence), fasting insulin (FIN), diastolic blood pressure, BMI, and the outcomes of quality of life (QoL) in patients with T2DM. However, when Tai Chi was compared with other exercise, there was no between-group difference in the HbA1c, FBG, TC, TG, HDL, LDL, BMI, and waist circumference (WC). Furthermore, the findings showed that an increase at every 18 weeks in length or an 823-h increase in the total time of Tai Chi intervention resulted in approximately a one unit reduction in the SMD of FBG.ConclusionCompared with usual care, Tai Chi may improve HbA1c (with clinical significance), FBG, FIN, BMI, diastolic blood pressure, and outcomes of QoL in T2DM patients. The effects of Tai Chi were similar to those of other exercises on the HbA1c, FBG, TC, TG, HDL, LDL, BMI, and WC. Given the overall poor methodological quality and evidence quality, these findings should be treated cautiously.  相似文献   
7.
ObjectivesInhaled phage therapy has been revisited as a potential treatment option for respiratory infections caused by multidrug-resistant Pseudomonas aeruginosa; however, there is a distinct gap in understanding the dose–response effect. The aim of this study was to investigate the dose–response effect of Pseudomonas-targeting phage PEV31 delivered by the pulmonary route in a mouse lung infection model.MethodsNeutropenic BALB/c mice were infected with multidrug-resistant P. aeruginosa (2 × 104 colony-forming units) through the intratracheal route and then treated with PEV31 at three different doses of 7.5 × 104 (Group A), 5 × 106 (Group B), and 5 × 108 (Group C) plaque-forming units, or phosphate-buffered saline at 2 hours postinoculation. Mice (n = 5–7) were euthanized at 2 hours and 24 hours postinfection, and lungs, kidneys, spleen, liver, bronchoalveolar lavage fluid, and blood were collected for bacteria and phage enumeration.ResultsAt 24 hours postinfection, all phage-treated groups exhibited a significant reduction in pulmonary bacterial load by 1.3–1.9 log10, independent of the delivered phage dose. The extent of phage replication was negatively correlated with the dose administered, with log10 titre increases of 6.2, 2.7, and 9 for Groups A, B, and C, respectively. Phage-resistant bacterial subpopulations in the lung homogenate samples harvested at 24 hours postinfection increased with the treatment dose (i.e. 30%, 74%, and 91% in respective Groups A–C). However, the mutants showed increased susceptibility to ciprofloxacin, impaired twitching motility, and reduced blue-green pigment production. The expression of the inflammatory cytokines (IL-1ß and IL-6, and TNF-α) was suppressed with increasing PEV31 treatment dose.DiscussionThis study provides the dose–response effect of inhaled phage therapy that may guide dose selection for treating P. aeruginosa respiratory infections in humans.  相似文献   
8.
Abstract

Can a single fiber of amphibole asbestos increase the risk of lung cancer or malignant mesothelioma (MM)? Traditional linear no-threshold (LNT) risk assessment assumptions imply that the answer is yes: there is no safe exposure level. This paper draws on recent scientific progress in inflammation biology, especially elucidation of the activation thresholds for NLRP3 inflammasomes and resulting chronic inflammation, to model dose-response relationships for malignant mesothelioma and lung cancer risks caused by asbestos exposures. The modeling integrates a physiologically based pharmacokinetics (PBPK) front end with inflammation-driven two-stage clonal expansion (I-TSCE) models of carcinogenesis to describe how exposure leads to chronic inflammation, which in turn promotes carcinogenesis. Together, the combined PBPK and I-TSCE modeling predict that there are practical thresholds for exposure concentration below which asbestos exposure does not cause chronic inflammation in less than a lifetime, and therefore does not increase chronic inflammation-dependent cancer risks. Quantitative examples using model parameter estimates drawn from the literature suggest that practical thresholds may be within about a factor of 2 of some past exposure levels for some workers. The I-TSCE modeling framework explains previous puzzling aspects of asbestos epidemiology, such as why age at first exposure is a better predictor of lifetime MM risk than exposure duration. It may be a valuable tool for risk analysts when LNT assumptions are not justified due to inflammation response thresholds mediating dose-response relationships.  相似文献   
9.

Purpose

Using volumetric modulated arc therapy (VMAT) delivery technique gantry position, multi-leaf collimator (MLC) as well as dose rate change dynamically during the application. However, additional components can be dynamically altered throughout the dose delivery such as the collimator or the couch. Thus, the degrees of freedom increase allowing almost arbitrary dynamic trajectories for the beam. While the dose delivery of such dynamic trajectories for linear accelerators is technically possible, there is currently no dose calculation and validation tool available. Thus, the aim of this work is to develop a dose calculation and verification tool for dynamic trajectories using Monte Carlo (MC) methods.

Methods

The dose calculation for dynamic trajectories is implemented in the previously developed Swiss Monte Carlo Plan (SMCP). SMCP interfaces the treatment planning system Eclipse with a MC dose calculation algorithm and is already able to handle dynamic MLC and gantry rotations. Hence, the additional dynamic components, namely the collimator and the couch, are described similarly to the dynamic MLC by defining data pairs of positions of the dynamic component and the corresponding MU-fractions. For validation purposes, measurements are performed with the Delta4 phantom and film measurements using the developer mode on a TrueBeam linear accelerator. These measured dose distributions are then compared with the corresponding calculations using SMCP. First, simple academic cases applying one-dimensional movements are investigated and second, more complex dynamic trajectories with several simultaneously moving components are compared considering academic cases as well as a clinically motivated prostate case.

Results

The dose calculation for dynamic trajectories is successfully implemented into SMCP. The comparisons between the measured and calculated dose distributions for the simple as well as for the more complex situations show an agreement which is generally within 3% of the maximum dose or 3 mm. The required computation time for the dose calculation remains the same when the additional dynamic moving components are included.

Conclusion

The results obtained for the dose comparisons for simple and complex situations suggest that the extended SMCP is an accurate dose calculation and efficient verification tool for dynamic trajectory radiotherapy. This work was supported by Varian Medical Systems.  相似文献   
10.
The ACR Dose Index Registry (DIR) provides a new source of clinical radiation exposure data that has not been used previously to establish or update the relative radiation level (RRL) values in the ACR Appropriateness Criteria (AC). The results of a recent review of DIR data for 10 common CT examinations were compared with current ACR AC RRL values for the same procedures. The AC RRL values were previously determined by consensus of members of the AC Radiation Exposure Subcommittee based on reference radiation dose values from the literature (when available) and anecdotal information from individual members’ clinical practices and experiences. For 7 of the 10 examination types reviewed, DIR data agreed with existing RRL values. For 3 of 10 examination types, DIR data reflected lower dose values than currently rated in the AC. The Radiation Exposure Subcommittee will revise these RRL assignments in a forthcoming update to the AC (in October 2018) and will continue to monitor the DIR and associated reviews and analyses to refine RRL assignments for additional examination types. Given recent attention and efforts to reduce radiation exposure in CT and other imaging modalities, it is likely that other examination types will require revision of RRL assignments once information from the DIR database is considered.  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