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   24213篇
  免费   1534篇
  国内免费   641篇
耳鼻咽喉   80篇
儿科学   161篇
妇产科学   162篇
基础医学   2013篇
口腔科学   271篇
临床医学   2593篇
内科学   4956篇
皮肤病学   154篇
神经病学   1256篇
特种医学   3871篇
外国民族医学   5篇
外科学   1570篇
综合类   3670篇
现状与发展   1篇
预防医学   938篇
眼科学   1885篇
药学   1733篇
  9篇
中国医学   328篇
肿瘤学   732篇
  2024年   95篇
  2023年   392篇
  2022年   720篇
  2021年   906篇
  2020年   785篇
  2019年   663篇
  2018年   701篇
  2017年   587篇
  2016年   637篇
  2015年   666篇
  2014年   1447篇
  2013年   1422篇
  2012年   1490篇
  2011年   1597篇
  2010年   1380篇
  2009年   1390篇
  2008年   1311篇
  2007年   1425篇
  2006年   1205篇
  2005年   1048篇
  2004年   838篇
  2003年   702篇
  2002年   612篇
  2001年   507篇
  2000年   385篇
  1999年   364篇
  1998年   360篇
  1997年   342篇
  1996年   264篇
  1995年   248篇
  1994年   203篇
  1993年   165篇
  1992年   147篇
  1991年   119篇
  1990年   108篇
  1989年   117篇
  1988年   83篇
  1987年   93篇
  1986年   83篇
  1985年   144篇
  1984年   117篇
  1983年   65篇
  1982年   101篇
  1981年   79篇
  1980年   72篇
  1979年   45篇
  1978年   58篇
  1977年   36篇
  1976年   27篇
  1975年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Computed tomographic (CT) angiography has become a valuable diagnostic technique prior to lower extremity arterial reconstruction. The purpose of this study is to evaluate its accuracy, compared to conventional angiography for planning lower limb revascularization procedures.

Patients and Methods: A prospective study was performed on all patients who underwent lower extremity arterial reconstruction procedures and had both CT angiography and conventional angiography between October 2003 and November 2005. We compared both modalities of angiography to intra-operative findings and whether a change in operative procedure would have resulted. The time for performance of both techniques and their complications were also reported.

Results: Sixty nine patients were included in this study. Discrepancies between intra-operative findings and CT angiography were noted in four (6%) cases while there was none with conventional angiography (p = 0.127). Disagreements between intra-operative findings and CT angiography have lead to a different procedure in three (4.5%) cases and all were infra-inguinal. The time for performance of CT angiography was significantly shorter than that for conventional angiography (2.5 ± 0.3 minutes vs 37.5 ± 5.2, p = 0.006).

Conclusion: For arterial reconstructive procedures CT angiography provides a less invasive and accurate imaging with short examination time. It can be used as a primary imaging modality in evaluation of lower limb ischemia.  相似文献   
992.
《Renal failure》2013,35(8):928-934
Objective: Contrast-induced nephropathy (CIN) is a serious complication of diagnostic and therapeutic coronary angiography. There are an increasing number of guidelines in the literature to help lessen this complication. Practice patterns in the cardiology community remain relatively unknown. This survey is an effort to better understand such practices. Methods: Questions were written based on the American College of Cardiology (ACC), the American Heart Association (AHA), and the Society of Cardiovascular Angiography and Intervention (SCAI) guidelines to identify cardiologist background and experience. The survey was emailed to 5000 randomly chosen cardiologists in December 2009. Results: A total of 291 responses were received. Among these, 97% reported checking renal function in all patients prior to angiography, 45% checked both estimated glomerular filtration rate (eGFR) and serum creatinine (SCr), 31% checked SCr alone, 19% checked eGFR alone, and 2% checked albumin-to-creatinine (A–C) ratio. Among responding cardiologists, 70% considered eGFR level less than 60 mL/min/1.73 m2 a high risk for CIN whereas 25% considered a level less than 30 mL/min/1.73 m2 a high risk. Thirty percent used only isosmolar media in high-risk patients, 33% used only low osmolar media, and 37% used either one. Conclusions: There is significant diversity in the measures taken by cardiologists to prevent CIN. More studies and clearer guidelines are needed to unify the practices.  相似文献   
993.
[摘要]目的探讨外伤性颈内动脉海绵窦瘘的诊断和血管内治疗。方法对有头部外伤病史及典型临床表现的患者积极行数字减影血管造影(digitalsubtractionangiography,DSA)检查,有4例确诊后经股动脉入路,用可脱性球囊进行栓塞治疗。3例保持了患侧颈内动脉的通畅,1例行瘘口远近端的颈内动脉闭塞术;3例患者应用1个球囊,1例应用2个球囊。结果4例患者瘘I:1完全闭塞,临床症状缓解,1例于首次术后12h症状再发,再次行栓塞治疗后缓解痊愈。结论DSA检查是诊断颈内动脉海绵窦瘘的金标准;可脱性球囊栓塞治疗是颈内动脉海绵窦瘘的首选治疗方法。  相似文献   
994.
PurposeTo prospectively compare the diagnostic capabilities of computed tomography angiography (CTA) to those of digital subtraction angiography (DSA) in endurance athletes with suspicion of arterial endofibrosis.Materials and methodsForty-five athletes (39 men, 6 women; median age: 30 years, interquartile range: 23–42 years) prospectively underwent DSA and CTA without (n = 5) or with (n = 40) electrocardiogram gating. DSA was interpreted by a single expert (experience of 15 years). CTA was independently interpreted by three other readers (experience of 5–8 years). Readers assessed the presence and degree of stenoses on iliac and femoral arteries and the overall diagnosis (negative, uncertain, positive) of endofibrosis at the limb level. Sensitivities and specificities of DSA and CTA were estimated at the limb level using histological findings and long-term follow-up as reference, and compared using the McNemar test.ResultsFor diagnosing and quantifying stenoses, concordance between DSA and CTA was moderate-to-good for common and external iliac arteries, moderate for lateral circumflex arteries and poor-to-moderate for the other branches of the deep femoral artery. It was good for all readers for the overall diagnosis of endofibrosis. After long-term follow-up (median, 95 months; interquartile range: 7–109 months), DSA sensitivity and specificity were respectively 88.6% (39/44; 95% confidence interval [CI]: 76–95%) and 75% (24/32; 95% CI: 57.9–86.7%); CTA sensitivity and specificity were respectively 88.6% (39/44; 95% CI: 76–95%; P > 0.99) and 84.4% (27/32; 95% CI: 68.2–93.1%; P = 0.51), 86.3% (38/44; 95% CI: 73.3–93.6%; P > 0.99) and 75% (24/32; 95% CI: 57.9–86.7%; P > 0.99), and 84.1% (37/44; 95% CI: 70.6–92.1%; P = 0.68) and 75% (24/32; 95% CI: 57.9–86.7%; P > 0.99) for the three readers.ConclusionCTA shows performances similar to those of DSA in predicting the long-term diagnosis of endofibrosis in endurance athletes with suggestive symptoms.  相似文献   
995.
  1. Download : Download high-res image (262KB)
  2. Download : Download full-size image
  相似文献   
996.
目的分析超选择性肾动脉弹簧圈栓塞术(SRACE)治疗经皮肾镜碎石取石术(PCNL)术后严重出血的时机选择、安全性和疗效。方法回顾性分析贵州省人民医院2013年10月至2019年3月38例PCNL后严重出血患者的出血特点、数字减影血管造影(DSA)表现及栓塞后肾功能检测情况。结果38例患者中,7例未观察到确切出血点,31例DSA表现为肾动脉性出血,其中动脉撕裂6例,单纯假性动脉瘤(PA)17例,动静脉瘘(AVF)4例,PA合并AVF 4例。根据肾脏血管解剖位置定位,肾动脉上极支出血4例,中极支出血9例,下极支出血18例。急性出血2例,其中1例经SRACE联合输血等治疗后未能有效控制出血而行患肾切除术,迟发性出血20例,缓慢持续性出血16例。31例患者中30例成功栓塞,成功率为96.8%。SRACE术前与术后的肾小球滤过率(P=0.173)、血清尿素氮(P=0.969)、血清肌酐(P=0.180)差异均无统计学意义(P>0.05)。结论急性出血应尽快行DSA明确诊断后行栓塞治疗,迟发性及缓慢持续性出血经保守治疗无效,DSA/SRACE可作为首选的检查方法及治疗方法,SRACE是安全有效的治疗方式。  相似文献   
997.
Summary Background. A prospective study was performed comparing the accuracy of digital subtraction angiography (DSA) and Doppler ultrasonography (DUS) stenosis findings with measurements on histological specimens. Method. DSA and DUS were used to evaluate carotid stenosis and were compared with measurements on histological specimens. Intact carotid plaques from 123 cases were removed in one piece during surgery. The specimens were histologically processed and examined in transverse sections. The smallest inner and correlating outer diameters were measured and the extent of stenosis was calculated. Carotid artery stenoses were compared and statistics done. Specimens in symptomatic cases were divided into 3 groups: stenosis 30–49% (Group 1), stenosis 50–69% (Group 2) and stenosis 70–99% (Group 3). Specimens in asymptomatic cases were divided into two groups: stenosis ≤59% (Group A) and stenosis ≥60% (Group B). Findings. Wilcoxon paired tests revealed significant differences between DSA, DUS and measurements on histological specimens. In severe stenoses only, no significant difference was observed between stenosis measurement according to the European Carotid Surgery Trial (ECST) angiography methodology and measurements on histological specimens. The most pronounced differences were found between angiography methodology of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and measurements on histological specimens. When investigating how often preoperative measurement classified stenosis into the same Group of stenoses as postoperative measurement, DUS was the most accurate diagnostic tool. Conclusions. This study confirmed our previous results, i.e., angiography underestimates the degree of carotid artery stenosis. DUS seems to be more accurate in classifying stenoses into different groups to the extent of narrowing of the carotid arteries. These results make the position of angiography in diagnostic algorithm of carotid stenoses investigations even more questionable.  相似文献   
998.
BACKGROUND: In patients with chronic kidney disease (CKD), although strong associations have been observed between malnutrition and atherosclerosis, the relationship between serum albumin concentration and angiographic changes of coronary artery disease (CAD) remains poorly explored. The goal of the present study was, in patients with CKD, to clarify the relationship between the angiographic severity of CAD and serum albumin concentration reflecting either inflammation or nutrition or both. METHODS: In this study, 100 end-stage renal disease (ESRD) patients were enrolled, who commenced long-term dialysis therapy at our hospital and underwent coronary angiography within 3 months of the first haemodialysis (HD) session. Mean age was 63+/-11 years, 20% of the subjects were female and 62% had diabetes. Severity of CAD was evaluated in terms of (i) number of vessels exhibiting CAD (>or=75% stenosis) and (ii) Gensini score (GS). Clinical characteristics and laboratory findings were recorded at initiation of long-term HD therapy. We then evaluated a possible association with the presence and degree of CAD. RESULTS: Sixty-four patients exhibited signs of CAD. Forty-one among them (64%) had multivessel disease. On univariate logistic regression analysis, age, diabetes and hypoalbuminaemia were significantly associated with multivessel CAD. Univariate linear regression analysis demonstrated a positive correlation of age and diabetes with GS, and an inverse correlation of BMI and serum albumin level with GS. Stepwise regression analysis showed age and serum albumin level to be independently associated with multivessel CAD and GS. The ROC curves demonstrated best cut-off levels of age and albumin for predicting multivessel CAD to be 70 years and 3.15 g/dl, respectively. CONCLUSION: Hypoalbuminaemia at the initiation of dialysis is an important predictor of advanced CAD, particularly in male and in diabetic patients. It may reflect mainly a state of inflammation. However, malnutrition as a confounding factor cannot be entirely excluded.  相似文献   
999.
背景:植入寰椎侧块的双皮质螺钉存在损伤位于寰椎侧块前方的颈内动脉的风险。目的:通过对颈部三维CT血管成像多平面重建测量,研究寰椎侧块螺钉钉道与颈内动脉的位置关系,以避免寰椎侧块螺钉植入造成颈内动脉的损伤。方法:从2012年9月至2012年11月行头颈CT血管造影扫描的患者中选取寰枢椎及头颈部血管无明确病变者126例,利用其图像数据进行三维多平面重建成像,在寰椎侧块螺钉进钉平面上测量颈内动脉与寰椎前皮质的最短距离,寰椎侧块的宽度,颈内动脉内侧缘分别至寰椎正中线、过横突孔内侧缘的矢状线、过进钉点的矢状线的距离,并测量进钉点与颈内动脉内侧缘切线的外偏角,同时在进钉平面上根据寰椎侧块进行区域划分,根据颈内动脉内侧缘所在区域分析颈内动脉与寰椎侧块的位置关系。结果:在寰椎侧块螺钉进钉平面上,颈内动脉与寰椎前皮质的最短距离为(3.32±1.07)mm,有35侧(13.9%)小于2mm,最小值为1.49mm;颈内动脉内侧缘至寰椎正中线的距离为(22.99±2.86)mm;颈内动脉内侧缘与过横突孔内侧缘的矢状线距离为(1.08±1.50)mm,其中182侧(72.2%)颈内动脉内侧缘位于横突孔内侧;颈内动脉内侧缘与过进钉点的矢状线距离为(3.99±1.84)mm;进钉点与颈内动脉内侧缘切线的外偏角为(9.90±5.57)°,最小值为-4.6°,其中有17侧(6.7%)小于0°。各项测量指标左、右侧差异均无统计学意义(P〉0.05)。颈内动脉内侧缘位于侧块外侧有95侧(37.7%),位于侧块前方有157侧(62.3%),其中位于侧块前方区域外1/3有136侧(54.O%),位于侧块前方区域中1/3有21侧(8.3%),未发现有位于侧块前方内1/3及侧块内侧者。结论:颈内动脉位于寰椎侧块的前外侧方,采用5°的内偏钉道有利于避免寰椎双皮质侧块螺钉对颈内动脉的损伤,术前通过颈部三维CT血管成像可以清楚地显示两者的解剖位置关系,为寰椎侧块螺钉的安全植入提供帮助。  相似文献   
1000.
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