全文获取类型
收费全文 | 17921篇 |
免费 | 1097篇 |
国内免费 | 507篇 |
专业分类
耳鼻咽喉 | 158篇 |
儿科学 | 270篇 |
妇产科学 | 251篇 |
基础医学 | 1362篇 |
口腔科学 | 154篇 |
临床医学 | 2287篇 |
内科学 | 2224篇 |
皮肤病学 | 102篇 |
神经病学 | 734篇 |
特种医学 | 1218篇 |
外国民族医学 | 1篇 |
外科学 | 1713篇 |
综合类 | 3453篇 |
现状与发展 | 1篇 |
预防医学 | 1904篇 |
眼科学 | 363篇 |
药学 | 2158篇 |
13篇 | |
中国医学 | 587篇 |
肿瘤学 | 572篇 |
出版年
2024年 | 46篇 |
2023年 | 206篇 |
2022年 | 441篇 |
2021年 | 519篇 |
2020年 | 550篇 |
2019年 | 435篇 |
2018年 | 469篇 |
2017年 | 580篇 |
2016年 | 640篇 |
2015年 | 616篇 |
2014年 | 1434篇 |
2013年 | 1287篇 |
2012年 | 1481篇 |
2011年 | 1453篇 |
2010年 | 1150篇 |
2009年 | 967篇 |
2008年 | 928篇 |
2007年 | 918篇 |
2006年 | 795篇 |
2005年 | 627篇 |
2004年 | 557篇 |
2003年 | 441篇 |
2002年 | 362篇 |
2001年 | 294篇 |
2000年 | 297篇 |
1999年 | 268篇 |
1998年 | 209篇 |
1997年 | 208篇 |
1996年 | 177篇 |
1995年 | 154篇 |
1994年 | 110篇 |
1993年 | 82篇 |
1992年 | 89篇 |
1991年 | 60篇 |
1990年 | 48篇 |
1989年 | 62篇 |
1988年 | 57篇 |
1987年 | 49篇 |
1986年 | 41篇 |
1985年 | 60篇 |
1984年 | 56篇 |
1983年 | 37篇 |
1982年 | 44篇 |
1981年 | 41篇 |
1980年 | 37篇 |
1979年 | 26篇 |
1978年 | 23篇 |
1977年 | 22篇 |
1976年 | 24篇 |
1975年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Abstract: In an experimental dog model of acute biventricular failure, the effects of left ventricular (LV) assist on renal hemodynamics and function were evaluated. After the induction of severe cardiac failure by multiple ligation of the coronary arteries, LV assist with a 40 ml pneumatic pulsatile pump was initiated, and the aortic flow was maintained at control values. The right atrial pressure (RAP) rose to 21.3 mm Hg with the appearance of profound right ventricular (RV) failure. Renal arterial blood flow (RAF) decreased to about 60% of the control value after 2 h of LV assist. The urine volume decreased and renal function deteriorated progressively. RV assist decreased the RAP to 4.8 mm Hg, and the reduced RAF recovered. After 3 h of RV assist, the RAF returned to initial values and the urine volume increased, but renal function did not recover. Advanced biventricular failure with elevated RAP during LV assist reduced renal perfusion and impaired renal function and may be an indication for early RV assist 相似文献
62.
应用扫描电镜观察9位育龄期妇女正常和结扎后的输卵管上皮。结果表明:在输卵管结扎疤痕两侧各0.5cm处,粘膜上皮细胞的纤毛大量扭曲和粘连,局部上皮纤毛和微绒毛脱落,细胞形态不规则,而在距输卵管结扎疤痕两侧各1.0cm处,上皮细胞的纤毛和微绒毛形态和结构均正常。表明输卵管结扎后上皮的超微结构变化,使卵细胞输送功能丧失,可能是输卵管复通术后不孕的重要原因。因此,施行输卵管复通术时,输卵管疤痕切除的范围应不少于疤痕两侧各0.5cm,以提高输卵管复通率。此外,发现输卵管小孔仅位于输卵管积水处粘膜的分泌细胞间,可能与输卵管浆膜下毛细淋巴管相沟通,与引流输卵管积水有关。在输卵管积水处粘膜的表面纤毛细胞的纤毛大量脱落,微绒毛增生,许多纤毛细胞转变为分泌细胞。提出了形成输卵管积水新的发病机理。 相似文献
63.
G. V. Peersman F. L. Van de Vyver J. E. Lohman U. Lübke J. Gheuens E. Bellon A. Connelly J. J. Martin 《Acta neuropathologica》1988,76(6):628-632
Summary Chronic recurrent experimental allergic encephalomyelitis was induced in a strain 13 guinea pig by inoculation of isologous spinal cord homogenate. The spinal cord was obtained after perfusion with 4% paraformaldehyde and examined with nuclear magnetic resonance (NMR) imaging. Proton NMR spin echo images (repetition time: 3 s; echo times: 20 and 60 ms) were obtained from intact, isolated spinal cord in a 4.7 Tesla, 50 mm bore magnet. The slice thickness of the images was 380 m and the inplane resolution was 40×40 m. The images showed superficial areas of low signal intensity in the lateroventral regions of the white matter, in some instances with a seam of higher signal intensity. Neuropathologically, these abnormalities corresponded exactly to areas of demyelination. Control images did not show these abnormalities. The present high resolution imaging allowed a correlation between demyelination and abnormal NMR signals in a small laboratory animal with an inflammatory demyelinating disease.Supported by the Belgian Foundation of Medical Scientific Research (FGWO, grant 3.0096.86 and grant 3.0019.86), by the Institute for the promotion of Scientific Research in Industry and Agriculture (IWONL) and by the Scientic Research Planning Office of the Belgian Government (DPWB), contract no. 87/92-120 相似文献
64.
背景 随着代谢性疾病发病率的上升,代谢综合征(MS)的预防与控制引起广泛的关注。而脂质比值是重要的筛查指标之一,与MS之间的关系成为热点研究话题。目的 基于贵州省多阶段横断面研究人群分析三酰甘油/高密度脂蛋白胆固醇(TG/HDL-C)、总胆固醇/HDL-C(TC/HDL-C)、低密度脂蛋白胆固醇/HDL-C(LDL-C/HDL-C)及非高密度脂蛋白胆固醇(non-HDL-C)与MS发病风险的关联及预测价值评价。方法 回顾性选取贵州省参与2010年全国疾病监测地区慢性病及危险因素调查、2013年中国慢性病及其危险因素监测、2015年中国成人慢性病与营养监测和2018年中国成人慢性病与营养监测的21 727例自然人群为研究对象,收集研究对象的基线资料,根据是否患有MS将研究对象分为MS组(n=4 981)和非MS组(n=16 746)。绘制受试者工作特征曲线(ROC曲线)分别评价男性和女性TG/HDL-C、TC/HDL-C、LDL-C/HDL-C和non-HDL-C对MS的预测价值。通过Delong检验比较脂质比值预测MS发生的ROC曲线下面积(AUC)的差异。采用多因素Logistic回... 相似文献
65.
Greg V. Stiegmann John S. Goff John H. Sun Deborah Davis Dean Silas 《Surgical endoscopy》1989,3(2):73-78
Summary Endoscopic variceal ligation (EVL) is a new technique designed to be used instead of sclerotherapy. Small elastic O rings ligate varices resulting in their strangulation and eradication. During a 12-month period, EVL was employed in 53 consecutive patients, of whom 36 (68%) had alcoholic cirrhosis 17 were Child-Pugh class A, 22 class B, and 14 class C. Varices were graded from I to IV and repeat treatments were given at 1–2 week intervals until the varices were eliminated. At follow-up ranging from 6–18 months (mean 11.5), 217 EVL treatment sessions had been performed. Of the 13 patients (24%) who died during the study, 11 died during the index hospitalization. Active bleeding was controlled in 19 of 21 patients (90%). Of 40 survivors 13 patients (33%) had 1–2 (mean 1.4) recurrent variceal bleeds while 34 patients had repeat EVL treatment. Elimination of distal varices was achieved in 26 and 7 had reduction of varices from grade III–IV to grade I–II or less. Eradication required a mean of 4.4 EVL sessions in Child's A and B patients and 7.0 sessions in Child's C patients (P<0.025). No significant treatment-related complications were observed. EVL appears to control active bleeding, is associated with a low incidence of non-bleeding complications, and may be used as an alternative to sclerotherapy. 相似文献
66.
目的 通过对人胎盘CD133+细胞群中高增殖潜能集落形成细胞(HPP-CFC)检测与生物学特性的分析,证明人胎盘存在早期造血干/祖细胞(HSPC)。 方法 采用机械法制备人胎盘组织(PT)单细胞悬液,用Histopaque-1007分离出单个核细胞(MNC),经磁式分选(MACS)富集CD133+细胞,培养28 d后观察HPP-CFC集落形成能力,用流式细胞仪(FCM)对分选的细胞组份和HPP-CFC进行表型分析,实验全程用脐带血(UCB)作平行比较分析。 结果 培养28 d后,PT-CD133+与UCB-CD133+细胞组份分别扩增了266和362倍,前者低于后者(P<0.01);PT-CD133+与UCB-CD133+细胞中HPP-CFC分别为(32.4±11.2)/5×103、(17. 7±5.7)/5×103,前者形成的HPP-CFC数量明显高于后者(P<0.01);PT-CD133+、UCB-CD133+细胞培养至28 d时,除UCB-CD133+组的CD133+CD34-亚群比例无明显改变外,CD133+CD34+、CD133-CD34+和CD133+CD34-(PT-CD133+组)亚型均比培养前减少。 结论 人胎盘组织CD133+细胞中存在HPP-CFC,说明胎盘CD133+细胞群中存在早期HSPC。 相似文献
67.
目的总结二微孔法腹腔镜下精索内静脉高位结扎的临床经验。方法二微孔法行腹腔镜下精索内静脉高位结扎术53例,其中左侧曲张39例,双侧陆张14例。结果患者手术均获成功,无并发症发生,平均手术时间30min,术后平均住院3d。结论二微孔法行腹腔镜下精索内静脉高位结扎术是一种可选的术式,患者痛苦小,损伤轻,恢复快,更具有美容、微创的治疗效果,操作难度不大。 相似文献
68.
目的探讨高压电烧伤对家兔血液流变学的影响及已酮可可碱对血液流变学异常的改善作用。方法将40只家兔随机分为高压电烧伤组(电伤组)、高压电烧伤复合已酮可可碱治疗组(复合组),每组20只。采用BV-100型悬丝生物流变仪,检测两组家兔伤前1 h、伤后即刻、伤后24 h、伤后48 h共四个时相的血液流变学指标,指标包括全血黏度(ηb)、全血还原黏度(ηr)、血浆黏度(ηp)、血沉(ESR)、血沉方程K值(K)、红细胞比容(HCT)、纤维蛋白原(FB)、红细胞聚集指数(EAI)、红细胞刚性指数(TK),对检测结果进行统计学分析。结果1、组内比较:电伤组和复合组ηb、ηr和EAI伤后各时相值均较伤前1 h升高(P<0.05);ηp、ESR、K、HCT、FB均从伤后24 h升高,24、48 h与伤前1 h比较均有显著性差异(P<0.05);电伤组TK于24、48 h升高,与伤前1 h比较均有显著性差异,而复合组TK伤后各时相与伤前比较无显著性差异(P>0.05)。2、组间同时相比较:复合组伤后各时相ηb和ηr均低于电伤组(P<0.05);复合组伤后24、48 h两个时相的ηp、ESR、K、HCT、FB、EAI、TK均低于电伤组(P<0.05)。结论高压电烧伤可引起家兔血液流变学异常,已酮可可碱对高压电引起的血液流变学异常有改善作用。 相似文献
69.
Scott D Rycroft JA Aspen J Chapman C Brown B 《European journal of applied physiology》2004,91(4):493-498
The effect of drinking tea on hydration status and mood was studied in nine male and four female members of expeditions based at Mt. Everest base camp at an altitude of 5,345 m. Whilst exposed to altitude-cold diuresis, participants were subjected to a crossover experimental design comprising two 24-h dietary interventions. In the tea condition, hot brewed tea formed a major part of fluid intake, whereas in the no-tea condition tea was excluded from the diet. Subjects were prohibited in both cases from consuming other caffeinated beverages, caffeinated foods, and alcoholic drinks. Mean fluids ingested [mean (SE); tea=3,193 (259) ml versus no tea=3,108 (269) ml] and urine volume (tea=2,686 (276) ml versus no tea=2,625 (342) ml] were similar under both conditions. Statistical analysis found no difference in urine stimulated as a result of the tea intervention (P=0.81). Several markers of hydration status were also taken immediately pre and post each condition, including measures of urine specific gravity, urine electrolyte balance (K+, Na+), and urine colour. None of these measures indicated a difference in hydration status as a result of the dietary intervention in either the control or tea condition. A difference was, however, found in mood, with subjects reporting reduced fatigue when tea was included in the diet (P=0.005). The study shows therefore that even when drunk at high altitude where fluid balance is stressed, there is no evidence that tea acts as a diuretic when consumed through natural routes of ingestion by regular tea drinkers, but that it does have a positive effect on mood. 相似文献
70.
实验高压电烧伤深筋膜微循环动态变化及意义 总被引:4,自引:7,他引:4
目的研究肢体高压电烧伤后深筋膜微循环变化规律。方法将28只家兔随机分成实验组与对照组。实验组家兔的右下肢采用1万伏额定电压 ,77mA电流及通电5s的方法制作单侧后肢电烧伤模型 ,对照组采用假电的方法制作单侧后肢假电烧伤模型 ,两组均采用“滴水开窗法”制作左侧下肢远端深筋膜微循环观测窗 ,并采用WX -9B型多部位微循环显微仪及其图像处理系统在通电前、通电后即刻、通电后30min、2、4、6h观测微动脉、毛细血管、后微静脉、微静脉的形态、流态、管周状态。结果肢体高压电烧伤后 ,微血管形态在30min内可观测到显著性变化 (P<0.05) ,表现为血管密度减小 ,微动脉、毛细血管、微静脉收缩 ,后微静脉扩张 ,微动脉、毛细血管均在6min以后变得不清以致模糊(P<0.05)、后微静脉、微静脉分别在2h、30min以后变得不清(P<0.05)。微血管内的流态以白微栓的变化可见规律性 ,即白微栓在电后2h开始出现 ,4h迅速达高峰 ,6h又有快速下降的趋势。微静脉和后微静脉在通电30min后有渗出(P<0.05) ,只有后微静脉在通电后2h有出血(P<0.05)。结论电烧伤后存在全身性反应 ,其在肢端深筋膜微循环的表现是一个阶段性加重的过程 :第一阶段电烧伤后30min内为缺血型微循环障碍 ,第二阶段微循环障碍包含两个方面 :其一是微血管的出血 相似文献