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   27279篇
  免费   2188篇
  国内免费   706篇
耳鼻咽喉   234篇
儿科学   777篇
妇产科学   213篇
基础医学   1604篇
口腔科学   1298篇
临床医学   4547篇
内科学   9992篇
皮肤病学   82篇
神经病学   705篇
特种医学   790篇
外科学   3572篇
综合类   3621篇
预防医学   643篇
眼科学   297篇
药学   1367篇
  16篇
中国医学   292篇
肿瘤学   123篇
  2024年   55篇
  2023年   572篇
  2022年   675篇
  2021年   1204篇
  2020年   1218篇
  2019年   1099篇
  2018年   1017篇
  2017年   870篇
  2016年   846篇
  2015年   866篇
  2014年   1752篇
  2013年   1734篇
  2012年   1339篇
  2011年   1450篇
  2010年   1298篇
  2009年   1223篇
  2008年   1257篇
  2007年   1320篇
  2006年   1143篇
  2005年   1193篇
  2004年   1004篇
  2003年   884篇
  2002年   725篇
  2001年   646篇
  2000年   538篇
  1999年   502篇
  1998年   467篇
  1997年   398篇
  1996年   342篇
  1995年   303篇
  1994年   245篇
  1993年   243篇
  1992年   234篇
  1991年   189篇
  1990年   196篇
  1989年   152篇
  1988年   142篇
  1987年   129篇
  1986年   104篇
  1985年   121篇
  1984年   93篇
  1983年   66篇
  1982年   75篇
  1981年   54篇
  1980年   49篇
  1979年   44篇
  1978年   33篇
  1977年   20篇
  1976年   17篇
  1975年   9篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
目的探讨心房充血分数(AFF)在评价高血压患者左室舒张功能方面的临床应用价值。方法应用声学定量技术(AQ)对40名高血压患者及40名正常人的AAF值,快充血率峰值(PRFR)进行测定,并兼测了二尖瓣口E峰峰值速度与A峰峰值速度比(EV/AV)。结果高血压患者的AFF值明显高于正常人(P<0·001);而PRFR、EV/AV值明显低于正常人(P<0·001~P<0·05)。且所有受试者的AFF值与EV/AV值、PRFR值分别呈负相关(r=-0·51;r=-0·61)。结论AFF能够客观的反映高血压患者的左室舒张功能变化,对鉴别左室舒张功能异常有一定的诊断意义。  相似文献   
72.
干下漏斗部室间隔缺损的外科治疗   总被引:9,自引:0,他引:9  
46例干下漏斗部室间隔缺损,占同期室缺手术治疗的23.2%(46/198)。缺损位于肺动脉瓣下34例,漏斗部12例。用带垫片褥式缝合修补21例,补片修补25例。全组无死亡。术后直接缝合组有主动脉关闭不全2例、残余分流2例,残留杂音3例。笔者认为,适时手术,选择适当的进路、应用补片修补、正确判断和处理主动脉瓣病变及对合并肺动脉狭窄者予以流出道补片加宽,是提高本病手术疗效的关键。  相似文献   
73.
1. Plasma potassium and chloride concentrations were raised and plasma renin activity, aldosterone, bicarbonate and arterial pH were reduced in two brothers with the syndrome of hypertension and hyperkalaemia with normal glomerular filtration rate (Gordon's syndrome), on unrestricted or moderately restricted sodium diets. 2. These abnormalities were corrected in both patients within 10 days of severe sodium restriction. 3. Pressor sensitivity to cold and angiotensin II decreased on low sodium diet, associated with a fall in blood pressure. 4. Increasing distal tubular sodium delivery by infusion of normal saline increased fractional excretion of potassium when aldosterone had been stimulated by severely restricted sodium diet, but not when aldosterone levels were low on unrestricted sodium diet. 5. These findings are consistent with excessive sodium reabsorption as the primary renal lesion in Gordon's syndrome, leading to volume expansion and suppression of renin and aldosterone. Severe dietary sodium restriction leading to volume contraction, by stimulating renin and aldosterone and promoting kaliuresis, corrects the abnormalities.  相似文献   
74.
颌面部爆炸伤软组织缺损早期修复的实验研究   总被引:16,自引:4,他引:12  
将犬随机分为A(即时)组、B(72h)组,采用KTY-04型雷管置于犬面颊部引爆致伤,造成软组织洞穿性缺损。A组伤后即刻清创、隐动脉皮瓣立即移植修复皮肤缺损;B组伤后即刻清创,72h后二次清创,同时切取隐动脉皮瓣,吻合血管修复皮肤缺损,颊粘膜缺损两组均行局部拉拢缝合。术后观察1~6个月,A组5例均失败;B组15例,成功12例,游离皮瓣成活率为80%。实验结果表明口腔颌面部爆炸伤软组织缺损经早期清创,72h后扩创,用吻合血管游离皮瓣修复是可行的。  相似文献   
75.
Bilateral ulnar agenesis is a rare abnormality. A total of 36 cases are analyzed: 35 of these are documented in the literature and 1 stillborn male is presented in this study. Most patients had one of the three conditions: Al-Awadi/Raas-Rothschild syndrome, syndrome of ulnar aplasia with split hand/split foot deformity, or the Brachmann—de Lange syndrome. Fifty percent of all cases with bilateral ulnar agenesis were associated with lower limb defects and these cases, for the most part, also belonged to the aforementioned syndromes. Nonskeletal, internal organ malformations were identified in 34% of all patients. Nine patients presented with isolated bilateral ulnar agenesis. The Al-Awadi/Raas-Rothschild syndrome and the split hand/split foot deformity are heritable disorders. There was no evidence for genetic etiology in most of the other cases. Bilateral ulnar agenesis in our fetus was part of the Brachmann—de Lange syndrome with associated cardiac defect, diaphragmatic hernia, and umbilical artery agenesis.  相似文献   
76.
A VDD pacing system with bipolar single-pass leads, were implanted in 36 consecutive patients (average age 72 ± 2years) with high degree atrioventricular block and normal sinus node function. At implant the atrial signal amplitude was 2.6 ± 0.2mV measured by a pacing system analyser (PSA), 1.8 ± 0.1mV measured peak-to-peak from the telemetered calibrated electrogram, and 1.3 ± 0.1mV measured from the sensing threshold. At one month follow-up the peak-to-peak amplitudes (mV) of the telemetered atrial electrograms were not significantly different measured continuously during resting supine with quiet breathing (1.4 ± 0.1), sitting (1.6 ± 0.2). standing (1.5 ± 0.1), arm swinging (1.4 ± 0.2), hyperventilation (1.3 ± 0.1), Vaisalva manoeuvre (1.4 ± 0.1), and treadmill exercise (1.9 ± 0.6). The telemetered atrial electrogram amplitude and the atrial sensing threshold varied between 1.2 ± 0.09mV and 1.8 ± 0.1mV, and between 0.95 ± 0.07mV and 1.3 ± 0.01mV, respectively at 0.5, 1, 3, 6 and 12 months follow-up, but the changes were statistically nonsignificant. The Event Summary showed sensing of 98% to 99% of the atrial events at the different follow-up periods.  相似文献   
77.
We describe a procedure for “chain-link” combined tissue transfer connecting the vascular pedicle of a deep circumflex iliac flap with that of a forearm flap after wide resection of the mandible. Combination of these flaps facilitated the reconstruction of the defect in both intra- and extraoral soft tissue and the mandibular bone. This method is useful when cervical recipient blood vessels are limited due to the wide resection of the primary tumor and radical neck dissection.  相似文献   
78.
非瓣膜病房颤患者左心耳血流动力学的TEE研究   总被引:1,自引:0,他引:1  
应用多平面经食管超声心动图技术(M-TEE),对30例健康人和30例非瓣病房颤患者(NVAF)心底短轴切面测量了左心耳最大直径,同一心动周期内左心耳最大及最小面积及左心耳最大空速度,产将NVAF患者按照自发显影及血栓的有无分为2组。发现NVAF组左心耳增大,收缩力及血流速度均减低,且这种变化在有血栓和有血栓形成倾向的患者中更为明显。  相似文献   
79.
The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.  相似文献   
80.
Ureteropelvic junction obstruction was noted in a newborn male infant with acro-pectoro-renal field defect. To our knowledge, this association has not previously been reported. Ultrasonography of the urinary tract should be performed on all children with aplasia of the pectoralis major muscle.  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