全文获取类型
收费全文 | 11203篇 |
免费 | 1222篇 |
国内免费 | 209篇 |
专业分类
耳鼻咽喉 | 114篇 |
儿科学 | 98篇 |
妇产科学 | 121篇 |
基础医学 | 431篇 |
口腔科学 | 126篇 |
临床医学 | 721篇 |
内科学 | 612篇 |
皮肤病学 | 41篇 |
神经病学 | 283篇 |
特种医学 | 2297篇 |
外科学 | 782篇 |
综合类 | 990篇 |
预防医学 | 1093篇 |
眼科学 | 81篇 |
药学 | 1016篇 |
5篇 | |
中国医学 | 374篇 |
肿瘤学 | 3449篇 |
出版年
2024年 | 30篇 |
2023年 | 146篇 |
2022年 | 287篇 |
2021年 | 455篇 |
2020年 | 421篇 |
2019年 | 648篇 |
2018年 | 618篇 |
2017年 | 413篇 |
2016年 | 409篇 |
2015年 | 386篇 |
2014年 | 818篇 |
2013年 | 666篇 |
2012年 | 735篇 |
2011年 | 700篇 |
2010年 | 544篇 |
2009年 | 624篇 |
2008年 | 540篇 |
2007年 | 477篇 |
2006年 | 488篇 |
2005年 | 368篇 |
2004年 | 249篇 |
2003年 | 242篇 |
2002年 | 219篇 |
2001年 | 184篇 |
2000年 | 159篇 |
1999年 | 148篇 |
1998年 | 177篇 |
1997年 | 128篇 |
1996年 | 113篇 |
1995年 | 112篇 |
1994年 | 68篇 |
1993年 | 49篇 |
1992年 | 41篇 |
1991年 | 45篇 |
1990年 | 46篇 |
1989年 | 44篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 45篇 |
1985年 | 128篇 |
1984年 | 107篇 |
1983年 | 87篇 |
1982年 | 83篇 |
1981年 | 86篇 |
1980年 | 79篇 |
1979年 | 79篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
目的 探讨根据患者个体差异调整管电流(mA),获得一致64层螺旋CT冠状动脉血管成像(CTCA)的图像噪声,进而控制辐射剂量的方法.方法 (1)80例患者作为固定mA组(650 mA)以一致的扫描条件进行64层螺旋CTCA检查.2名医师用5分法评价固定mA组的噪声水平以确定诊断图像质量所需要的噪声水平标准差(SD)SD.值,并建立一个少量对比剂团注探测循环时间扫描(TB)噪声SDTB值和心脏扫描(CA)达到SD0水平所需mA的关系式.(2)80例64层螺旋CTCA检查根据个体差异调整扫描mA,作为个体mA调制组与固定mA组进行比较,分析该方法的可操作性和辐射剂量的控制,两组均数比较用独立样本t检验.结果 (1)固定mA组的TB和CA的噪声SD呈线性相关(r2=0.994);(2)根据主观评价的结果将SD0定为28 HU可获得满意的图像质量;(3)个体mA调制组噪声平均值28.97 HU,SD为1.93,小于固定mA组的5.14,但质量评分(4.27±0.68)与固定mA组(4.03±0.93)差异无统计学意义(P>0.05);(4)个体mA调制组63例调整后<650 mA,平均CT剂量指数(CTDIvol)为58.32 mGy,比固定mA组(85.94 mGy)减少了32.1%,其中1例患者仪使用160 mA,CTDIvol=19.27 mGy,是固定mA组平均剂量的22.4%.结论 通过个体的TB噪声SD调整mA可获得一致心脏扫描噪声水平,是有效的实用的保证成像质量又对个体辐射剂量进行控制的方法. 相似文献
102.
低剂量增强多层螺旋CT对陈旧性心肌梗死心肌活性的评价 总被引:1,自引:0,他引:1
目的 前瞻性评价低剂量增强多层螺旋CT(MSCT)显示陈旧性心肌梗死心肌活性的可行性和可靠性,并与MR心肌灌注和心肌活性成像进行对照研究.方法 对32例临床明确诊断为陈旧性心肌梗死的患者行前瞻性首过和延迟增强64层MSCT及MR心肌灌注成像,在短轴面上将左心室分为16个心肌段进行分析,所有患者的MSCT和MR影像资料被双盲分析,确定早期心肌灌注缺损区和晚期延迟增强区的大小及范围.采用一致性检验的Kappa检验,评价两种方法对显示心肌活性的一致性.结果 32例患者,首过灌注期MSCT提示灌注缺损为41个节段,无灌注缺损为471个节段;首过灌沣期MRI提示灌注缺损为47个节段,无灌注缺损为465个节段,两种方法一致性Kappa值为0.650,符合率为94.5%(484/512).延迟期MSCT显示延迟增强为135个节段,其中非透壁性梗死为50个节段,透壁性梗死为85个节段,未出现延迟增强为377个节段;延迟期MRI显示延迟增强为120个节段,其中非透壁性梗死为56个节段,透壁性梗死为64个节段,未出现延迟增强为392个节段,两种方法一致性Kappa值为0.609,符合率为80.7%(413/512).结论 低剂量增强螺旋MSCT与MRI对心肌活性的评价有较好的相关性,MSCT对陈旧性心肌梗死的存活心肌和非存活心肌的检测是呵行和可靠的,减少不必要的X线辐射剂量是该研究的重要方面. 相似文献
103.
Turan Olgar Esra Onal Dogan Bor Nurullah Okumus Yildiz Atalay Canan Turkyilmaz Ebru Ergenekon Esin Koc 《Korean journal of radiology》2008,9(5):416-419
OBJECTIVE: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. MATERIALS AND METHODS: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESD(TO)) (n = 23) and from the use of thermoluminescent dosimetry (ESD(TLD)) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESD(TO) by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESD(TO) and ESD(TLD) were correlated using linear regression analysis. RESULTS: The mean ESD(TO) for the chest and abdomen were 67 microGy and 65 microGy per procedure, respectively. The mean ESD(TLD) per radiograph was 70 microGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 microGy) per radiograph. Mean effective doses were 16 and 27 microSv per procedure for the chest and abdomen, respectively. ESD(TLD) was well correlated with ESD(TO) obtained from the total chest and abdomen radiographs for each infant (R(2) = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 x 10(-6) to 2 x 10(-6) and 0.6 x 10(-6) to 2.9 x 10(-6) for chest and abdomen radiographs, respectively. CONCLUSION: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other. 相似文献
104.
目的 研究旋转磁场对小鼠骨髓型急性放射病的治疗效果。方法 132只雄性BALB/c小鼠随机分为正常组(N),单纯磁疗组(M),单纯照射组(R)和照射磁疗组(R+M)4组,N组小鼠不作其他处理,R组和R+M组小鼠接受6.0 Gy剂量的 60Co γ 射线照射,M组及R+M组予以磁场处理30d,每天2次,每次1.5h。观察小鼠30d的存活率和存活期;分别于0、5、9、15、21、30d检测外周血细胞数;测定第9、23、30d骨髓单核细胞数(BMNC)、脾集落形成单位(CFU-S)、脾脏指数(脾体比)、骨髓细胞周期、细胞凋亡,观察股骨骨髓病理切片及检测骨形态发生蛋白(BMP2/4)的表达水平。结果 1N组和M组小鼠无死亡。R+M组与R组比较,磁疗提高了小鼠的存活率和存活期(P<0.01)。2R+M组与R组比较,磁疗提高了R+M组第15天外周血白细胞数及血红蛋白含量、第21天红细胞数、第30天血小板数(P<0.05)。3第9天R+M组CFU-S、BMNC数、细胞G2+M期比例高于R组,而总凋亡率低于R组(P<0.05)。第23天脾脏指数R+M组高于R组(P<0.05)。4骨髓病理检查显示,磁场可促进照射后骨髓造血组织结构的修复,R组骨髓早期较空虚,而R+M组骨髓细胞较充盈,随着时间的推移,两者均逐渐恢复正常;R+M组的骨髓BMP2/4表达水平亦明显高于R组。结论 旋转磁场对放射损伤小鼠骨髓造血具有明显的保护作用,能减少骨髓细胞的凋亡,其机制可能是促进放射损伤后造血细胞和造血微环境的修复。 相似文献
105.
Outcomes of breast-conservation therapy for invasive lobular carcinoma are equivalent to those for invasive ductal carcinoma 总被引:2,自引:0,他引:2
Vo TN Meric-Bernstam F Yi M Buchholz TA Ames FC Kuerer HM Bedrosian I Hunt KK 《American journal of surgery》2006,192(4):552-555
BACKGROUND: Breast-conservation therapy (BCT), including wide local excision and postoperative irradiation, is considered standard treatment for early-stage invasive ductal carcinoma (IDC). The use of BCT in patients with invasive lobular carcinoma (ILC) has been questioned because of concerns regarding ipsilateral breast recurrence and risk of bilateral breast cancer. We evaluated our institutional experience with BCT and compared treatment outcomes for ILC with those for IDC. METHODS: A review of our BCT database revealed 84 patients with ILC and 1,126 with IDC with stage I or II disease treated with BCT and radiation between 1976 and 1999. We evaluated local-regional recurrence, disease-specific survival, and contralateral breast cancer rates in both groups. RESULTS: The 5- and 10-year local-regional recurrence rates for the ILC group were 1% and 7%, respectively, and 4% and 9%, respectively, for the IDC group (P = .70). There were no significant differences in the 5- and 10-year disease-specific survival rates between the groups. Contralateral breast cancer occurred in 11.3% of patients with IDC and 11.9% of patients with ILC. CONCLUSIONS: BCT achieves similar local-regional control and survival outcomes in selected patients with ILC or IDC. Breast-conservation therapy is an appropriate treatment strategy for patients with early-stage invasive lobular carcinoma. 相似文献
106.
Nicholas J. Giacalone William U. Shipley Rebecca H. Clayman Andrzej Niemierko Michael Drumm Niall M. Heney Marc D. Michaelson Richard J. Lee Philip J. Saylor Matthew F. Wszolek Adam S. Feldman Douglas M. Dahl Anthony L. Zietman Jason A. Efstathiou 《European urology》2017,71(6):952-960
Background
Tri-modality therapy (TMT) is a recognized treatment strategy for selected patients with muscle-invasive bladder cancer (MIBC).Objective
Report long-term outcomes of patients with MIBC treated by TMT.Design, setting, and participants
Four hundred and seventy-five patients with cT2–T4a MIBC were enrolled on protocols or treated as per protocol at the Massachusetts General Hospital between 1986 and 2013.Intervention
Patients underwent transurethral resection of bladder tumor followed by concurrent radiation and chemotherapy. Patients with less than a complete response (CR) to chemoradiation or with an invasive recurrence were recommended to undergo salvage radical cystectomy.Outcome measurements and statistical analysis
Disease-specific survival (DSS) and overall survival (OS) were calculated using the Kaplan-Meier method.Results and limitations
Median follow-up for surviving patients was 7.21 yr. Five- and 10-yr DSS rates were 66% and 59%, respectively. Five- and 10-yr OS rates were 57% and 39%, respectively. The risk of salvage cystectomy at 5 yr was 29%. In multivariate analyses, T2 disease (OS hazard ratio [HR]: 0.57, 95% confidence interval [CI]: 0.44–0.75, DSS HR: 0.51, 95% CI: 0.36–0.73), CR to chemoradiation (OS HR: 0.61, 95% CI: 0.46–0.81, DSS HR: 0.49, 95% CI: 0.34–0.71), and presence of tumor-associated carcinoma in situ (OS HR: 1.56, 95% CI: 1.17–2.08, DSS HR: 1.50, 95% CI: 1.03–2.17) were significant predictors for OS and DSS. When evaluating our cohort over treatment eras, rates of CR improved from 66% to 88% and 5-yr DSS improved from 60% to 84% during the eras of 1986–1995 to 2005–2013, while the 5-yr risk of salvage radical cystectomy rate decreased from 42% to 16%.Conclusions
These data demonstrate high rates of CR and bladder preservation in patients receiving TMT, and confirm DSS rates similar to modern cystectomy series. Contemporary results are particularly encouraging, and therefore TMT should be discussed and offered as a treatment option for selected patients.Patient summary
Tri-modality therapy is an alternative to radical cystectomy for patients with muscle-invasive bladder cancer, and is associated with comparable long-term survival and high rates of bladder preservation. 相似文献107.
《Journal of vascular surgery》2023,77(2):366-373
ObjectiveEndovascular treatment of complex aortic pathology has been associated with increases in procedural-related metrics, including the operative time and radiation exposure. Three-dimensional fusion imaging technology has decreased the radiation dose and iodinated contrast use during endovascular aneurysm repair. The aim of the present study was to report our institutional experience with the use of a cloud-based fusion imaging platform during fenestrated endovascular aneurysm repair (FEVAR).MethodsA retrospective review of a prospectively maintained aortic database was performed to identify all patients who had undergone FEVAR with commercially available devices (Zenith Fenestrated; Cook Medical Inc, Bloomington, IN) between 2013 and 2020 and all endovascular aneurysm repairs performed using Cydar EV Intelligent Maps (Cydar Medical, Cambridge, UK). The Cydar EV cohort was reviewed further to select all FEVARs performed with overlay map guidance. The patient demographic, clinical, and procedure metrics were analyzed, with a comparative analysis of FEVAR performed without and with the Cydar EV imaging platform. Patients were excluded from comparative analysis if the data were incomplete in the dataset or they had a documented history of prior open or endovascular abdominal aortic aneurysm repair.ResultsDuring the 7-year study period, 191 FEVARs had been performed. The Cydar EV imaging platform was implemented in 2018 and used in 124 complex endovascular aneurysm repairs, including 69 consecutive FEVARs. A complete dataset was available for 137 FEVARs. With exclusion to select for de novo FEVAR, a comparative analysis was performed of 53 FEVAR without and 63 with Cydar EV imaging guidance. The cohorts were similar in patient demographics, medical comorbidities, and aortic aneurysm characteristics. No significant difference was noted between the two groups for major adverse postoperative events, length of stay, or length of intensive care unit stay. The use of Cydar EV resulted in nonsignificant decreases in the mean fluoroscopy time (69.3 ± 28 minutes vs 66.2 ± 33 minutes; P = .598) and operative time (204.4 ± 64 minutes vs 186 ± 105 minutes; P = .278). A statistically significant decrease was found in the iodinated contrast volume (105 ± 44 mL vs 83 ± 32 mL; P = .005), patient radiation exposure using the dose area product (1,049,841 mGy/cm2 vs 630,990 mGy/cm2; P < .001) and cumulative air kerma levels (4518 mGy vs 3084 mGy; P = .02) for patients undergoing FEVAR with Cydar EV guidance.ConclusionsAt our aortic center, we have observed a trend toward shorter operative times and significant reductions in both iodinated contrast use and radiation exposure during FEVAR using the Cydar EV intelligent maps. Intelligent map guidance improved the efficiency of complex endovascular aneurysm repair, providing a safer intervention for both patient and practitioner. 相似文献
108.
目的 探讨单纯膝关节镜手术与联合术后放疗治疗膝关节弥漫性色素绒毛结节性滑膜炎(DPVNS)的临床疗效和安全性。方法 武汉市中心医院及北京军区总医院于2009年1月至2014年1月收治的30例膝关节DPVNS患者,平均病程为35.6个月(4~121个月)。按患者治疗意愿分为手术联合术后放射治疗(联合治疗)组16例,单纯手术组14例。联合治疗组行关节镜下滑膜切除联合术后局部放射治疗,总剂量40 Gy,每次2 Gy。所有患者治疗后平均随访时间38.7个月(12~72个月),比较两组术后复发率、KSS临床评分和功能评分。结果 联合治疗组优良率(14/16)明显高于单纯手术组(11/14)(χ2=9.87,P<0.05),且复发率(1/16)明显低于单纯手术组(3/14)(χ2=1.83,P<0.05),治疗后KSS临床评分和功能评分改善明显优于单纯手术组(χ2=15.00、15.78,P<0.05)。放疗的不良反应为白细胞下降、肢体浮肿、皮肤出现色素沉着,联合治疗组患者均能较好地耐受。结论 关节镜术后放疗治疗膝关节DPVNS是一种安全有效的治疗手段,值得临床推广应用。 相似文献
109.
目的 观察低剂量CT引导下Hookwire穿刺用于定位体质量指数(BMI) ≤ 22 kg/m2患者肺结节的可行性。方法 前瞻性招募53例BMI ≤ 22 kg/m2的肺结节患者(共66枚肺结节)行CT引导下Hookwire穿刺定位,根据CT剂量分为常规剂量组(A组,25例32枚肺结节)及低辐射剂量组(B组,28例34枚肺结节),以B组此前常规剂量CT图像为其对照组(C组)。采用5分制对A、B组CT图像质量进行评分,以3分制评价B、C组图像显示肺结节状态。比较A、B组患者一般资料、肺结节位置、类型、CT值、最大径、图像质量评分、穿刺次数、并发症、容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(ED)等,比较B、C组图像显示肺结节评分、结节最大径及CT值。结果A、B组患者一般资料、肺结节位置、类型、CT值、最大径、穿刺次数及并发症差异均无统计学意义(P均>0.05)。B组图像质量评分[4(3,4)]低于A组[5(4,5)](P<0.05)但均 ≥ 3分,可满足穿刺定位需求。B组CTDIvol、DLP和ED均低于A组(P均<0.05)。B、C组图像显示肺结节评分、结节最大径、CT值差异均无统计学意义(P均>0.05)。结论 低剂量CT引导下Hookwire穿刺可用于定位BMI ≤ 22 kg/m2患者肺结节。 相似文献
110.
目的 探讨髋关节数字化断层融合(DTS)摄影中最佳剂量比的设定,以最大程度地减少患者接受的辐射剂量.方法 90例行髋关节数字化断层融合摄影的患者,以随机数字表法,分别以6、7、8倍的剂量比组进行DTS检查,使用单因素方差分析比较不同剂量比设定下所得的图像质量和辐射剂量.结果 3组的表面吸收剂量(ESD)、剂量面积乘积(DAP)、图像质量评分分别为[(3.76±1.89)mGy、(18.41±11.71)dGy ·cm2、3.03±0.24]、[(5.24±2.76)mGy、(26.99±13.34)dGy ·cm2)、3.60±0.11]、[(6.39±1.75)mGy、(36.96±22.49)dGy ·cm2、3.64±0.09],各组间差异有统计学意义(F=10.94、9.45、139.26, P<0.05),通过3组间两两比较,ESD值和DAP值均是6倍剂量比组<7倍剂量比组<8倍剂量比组.6倍剂量比组的图像质量评分低于其他两组,7倍剂量比组和8倍剂量比组的图像质量评分差异无统计学意义.结论 剂量比是决定DTS检查辐射剂量的重要参数,髋关节DTS检查的剂量比设置为7时,可实现低曝光剂量和高图像质量的平衡,以最大限度地保护患者免受不必要的辐射损害. 相似文献