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   174446篇
  免费   17114篇
  国内免费   10155篇
耳鼻咽喉   1463篇
儿科学   2727篇
妇产科学   1038篇
基础医学   11036篇
口腔科学   3599篇
临床医学   21079篇
内科学   16071篇
皮肤病学   1840篇
神经病学   4272篇
特种医学   6145篇
外国民族医学   11篇
外科学   15358篇
综合类   46815篇
现状与发展   50篇
一般理论   6篇
预防医学   20560篇
眼科学   2291篇
药学   21631篇
  242篇
中国医学   17065篇
肿瘤学   8416篇
  2024年   898篇
  2023年   2361篇
  2022年   6029篇
  2021年   7544篇
  2020年   6499篇
  2019年   3866篇
  2018年   3906篇
  2017年   5078篇
  2016年   3999篇
  2015年   6961篇
  2014年   9246篇
  2013年   10952篇
  2012年   15618篇
  2011年   16600篇
  2010年   14815篇
  2009年   13230篇
  2008年   13546篇
  2007年   13012篇
  2006年   11718篇
  2005年   9271篇
  2004年   6798篇
  2003年   5481篇
  2002年   4331篇
  2001年   3831篇
  2000年   2761篇
  1999年   1119篇
  1998年   352篇
  1997年   318篇
  1996年   270篇
  1995年   214篇
  1994年   223篇
  1993年   168篇
  1992年   100篇
  1991年   80篇
  1990年   81篇
  1989年   55篇
  1988年   39篇
  1987年   55篇
  1986年   41篇
  1985年   42篇
  1984年   25篇
  1983年   28篇
  1982年   26篇
  1981年   10篇
  1959年   15篇
  1958年   19篇
  1957年   14篇
  1956年   7篇
  1955年   7篇
  1954年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
吴仪 《中国骨伤》2007,20(9):585-586
2007年1月11日,中共中央政治局委员、国务院副总理吴仪在全国中医药工作会议上发表了重要讲话,该讲话从4个方面进行了论述,节选如下。  相似文献   
12.
目的探讨术中应用前列腺素E1(prostaglandin E1,PGE1)对大鼠肝移植肾功能的保护作用。方法大鼠原位肝移植术中经颈内静脉灌注PGE1为治疗组,生理盐水和空白为对照组,观察术后1周存活率、1h的尿量,测定血浆肌酐、尿素氮和肾组织中丙二醛(malondjaldehyde,MDA)、谷胱甘肽(glutathione,GSH)含量,肾组织病理检查。结果PGE1治疗组术后1h尿量较对照组明显增加,肌酐和尿素氮水平均较对照组降低,PGE1治疗组肾组织中GSH含量显著高于两对照组,MDA含量低于两对照组。病理检查PGE1治疗组肾脏组织形态学损伤明显减轻。结论术中应用PGE1能显著改善大鼠肝移植后的肾功能,其机制可能与对抗氧自由基损伤作用有关。  相似文献   
13.
Atrial electrical remodeling plays a part in recurrence of atrial fibrillation (AF). It has been related to an increase in heterogeneity of atrial refractoriness that facilitates the occurrence of multiple reentry wavelets and vulnerability to AF. AIM: To examine the relationship between dispersion of atrial refractoriness (Disp_A) and vulnerability to AF induction (A_Vuln) in patients with clinical paroxysmal AF (PAF). METHODS: Thirty-six patients (22 male; age 55+/-13 years) with > or =1 year of history of PAF (no underlying structural heart disease--n=20, systemic hypertension--n=14, mitral valve prolapse--n=1, surgically corrected pulmonary stenosis--n=1), underwent electrophysiological study (EPS) while off medication. The atrial effective refractory period (AERP) was assessed at five different sites--high (HRA) and low (LRA) lateral right atrium, high interatrial septum (IAS), proximal (pCS) and distal (dCS) coronary sinus--during a cycle length of 600 ms. AERP was taken as the longest S1-S2 interval that failed to initiate a propagation response. Disp_A was calculated as the difference between the longest and shortest AERP. A_Vuln was defined as the ability to induce AF with 1-2 extrastimuli or with incremental atrial pacing (600-300 ms) from the HRA or dCS. The EPS included analysis of focal electrical activity based on the presence of supraventricular ectopic beats (spontaneous or with provocative maneuvers). The patients were divided into group A--AF inducible (n=25) and group B--AF not inducible (n=11). Disp_A was analyzed to determine any association with A_Vuln. Disp_A and A_Vuln were also examined in those patients with documented repetitive focal activity. Logistic regression was used to determine any association of the following variables with A_Vuln: age, systemic hypertension, left ventricular hypertrophy, left atrial size, left ventricular function, duration of PAF, documented atrial flutter/tachycardia and Disp_A. RESULTS: There were no significant differences between the groups with regard to clinical characteristics and echocardiographic data. AF was inducible in 71% of the patients and noninducible in 29%. Group A had greater Disp_A compared to group B (105+/-78 ms vs. 49+/-20 ms; p=0.01). Disp_A was >40 ms in 50% of the patients without A_Vuln and in 91% of those with A_Vuln (p=0.05). Focal activity was demonstrated in 14 cases (39%), 57% of them with A_Vuln. Disp_A was 56+/-23 ms in this group and 92+/-78 ms in the others (p=0.07). Using logistic regression, the only predictor of A_Vuln was Disp_A (p=0.05). CONCLUSION: In patients with paroxysmal AF, Disp_A is a major determinant of A_Vuln. Nevertheless, the degree of nonuniformity of AERP appears to be less important as an electrophysiological substrate for AF due to focal activation.  相似文献   
14.
基于Labview虚拟仪器设计平台和相关原理,提出了在微弱光电信号检测中利用软件实现锁相检测的技术.文中同时对相关器进行了仿真,仿真结果证明此方法可以有效地实现对被调制的微弱光电信号的检测.  相似文献   
15.
目的 探讨肿瘤微血管密度(MVD)与肝细胞性肝癌临床病理及预后的关系。方法对30例肝细胞性肝癌根治性切除病理组织切片进行苏木精伊红染色.并用CD34单克隆抗体进行免疫组化染色,计数被CD34抗体染色的肿瘤血管内皮细胞数,以测定MVD。对MVD与临床病理因素及术后生存率关系进行分析。结果 单因素分析结果表明.MVD水平与肿瘤大小、TNM分期都是影响肝细胞性肝癌预后的因素;多因素分析结果表明.肝癌大小及肿瘤分期是肝细胞性肝癌独立预后因素。结论 MVD是肝细胞性肝癌一种预后因素。  相似文献   
16.
BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.  相似文献   
17.
This article discusses the cardiovascular protection afforded by low to moderate consumption of ethanol and the role of ethanol-induced preconditioning. Ethanol, a compound that is found in many popular beverages, has a whole range of cardiovascular protective effects when consumed in low to moderate doses. Although they have yet to be totally clarified, recent data suggest that a combination of several actions at the biochemical and molecular levels play a role in this protection. These include favorable changes in lipid metabolism, antioxidant effects, changes in hemostasis and platelet aggregation, arterial vasodilation mediated by NO release, induction of the expression of cardioprotective proteins, insulin sensitization and lower levels of inflammatory markers. Special emphasis will be given to ethanol-induced preconditioning. Some of the compounds present in red and white wine, such as resveratrol and quercetin, are also partly responsible for some of the cardioprotective effects of alcoholic drinks. These are due to antioxidant effects and changes in platelet aggregation, endothelial function and inflammatory response. The last part of the paper will focus on the clinical applications and possibilities raised by these new findings.  相似文献   
18.
矢状缝早闭(舟状头)全颅成形术   总被引:2,自引:1,他引:1  
目的探讨治疗矢状缝早闭(舟状头)畸形的手术方法。方法采用David“‖”形颅缝重建法(6例)、旋转骨瓣截骨法(2例)、梅花颅骨瓣头颅盖成型法(3例)等术式对舟状头进行矫治。结果11例患儿均治愈,外形满意。结论1~3个月舟状头宜采用简单的David“‖”形颅缝重建法进行治疗,3个月以上的患儿可选用浮动颅骨瓣头颅成型术、梅花瓣法颅骨瓣头颅盖成型术等方法进行治疗。  相似文献   
19.
目的:探讨提高嗜铬细胞瘤患者围手术期安全性的措施。方法:对15例嗜铬细胞瘤患者、术前采用选择性α1受体阻滞剂多沙唑嗪控释片(可多华)控制高血压;11例患者采用3D DCEMRA进行肿瘤定位;术中均采用联合高容量血液稀释(AHH)和术中患者自体血回输纠正血容量。结果:除1例持续性高血压患者需联合钙离子拮抗剂和ACEI药物降压外.其余患者血压控制均为满意;根据3D DCEMRA定位选择手术径路者均顺利完成手术;AHH联合术中自体血回输使14例患者避免了异体输血。结论:本文围手术期处理改进.可多华可明显减少药物的不良反应;采用3D DCEMRA进行肿瘤定位,可增加手术安全性;AHH联合术中自体血回输可减少医疗成本和异体输血,以及由此而引起的并发症。  相似文献   
20.
阻塞性黄疸:PTC下胆管钳夹活检的技术方法学研究   总被引:1,自引:0,他引:1  
目的探索切实可行的胆管病理学检查新途径.资料与方法连续92例阻塞性黄疸患者接受经皮肝穿刺胆管造影(PTC)和经皮肝穿胆管引流(PTCD)治疗.PTCD过程中,影像监测下经皮经肝胆管穿刺,向胆管内引入活检钳对梗阻段钳夹活检,行组织病理学检查.统计学分析用χ2检验或Fisher确切概率计算法,以α=0.05作为检验水准.结果 92例钳夹活检患者90例成功获得组织块,技术成功率97.83%(90/92).钳夹活检敏感性为88.04%,63例胆管癌性恶性肿瘤钳夹活检敏感性较25例非胆管癌性恶性肿瘤高(93.65%比72.00%,P<0.05).结论PTC下胆管钳夹活检操作简单,创伤小,敏感性高,是一种值得推广的胆管病理学诊断新途径.  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