全文获取类型
收费全文 | 3675篇 |
免费 | 241篇 |
国内免费 | 15篇 |
学科分类
医药卫生 | 3931篇 |
出版年
2023年 | 36篇 |
2022年 | 28篇 |
2021年 | 95篇 |
2020年 | 66篇 |
2019年 | 102篇 |
2018年 | 124篇 |
2017年 | 76篇 |
2016年 | 91篇 |
2015年 | 104篇 |
2014年 | 148篇 |
2013年 | 160篇 |
2012年 | 218篇 |
2011年 | 243篇 |
2010年 | 149篇 |
2009年 | 160篇 |
2008年 | 175篇 |
2007年 | 185篇 |
2006年 | 135篇 |
2005年 | 132篇 |
2004年 | 112篇 |
2003年 | 96篇 |
2002年 | 77篇 |
2001年 | 69篇 |
2000年 | 68篇 |
1999年 | 73篇 |
1998年 | 109篇 |
1997年 | 83篇 |
1996年 | 80篇 |
1995年 | 60篇 |
1994年 | 64篇 |
1993年 | 70篇 |
1992年 | 28篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 45篇 |
1988年 | 36篇 |
1987年 | 45篇 |
1986年 | 28篇 |
1985年 | 36篇 |
1984年 | 28篇 |
1983年 | 21篇 |
1982年 | 26篇 |
1981年 | 25篇 |
1980年 | 29篇 |
1979年 | 11篇 |
1978年 | 20篇 |
1977年 | 21篇 |
1976年 | 22篇 |
1975年 | 18篇 |
1970年 | 7篇 |
排序方式: 共有3931条查询结果,搜索用时 31 毫秒
1.
2.
3.
Needle-localized breast biopsy: why do we fail? 总被引:10,自引:0,他引:10
4.
Dani Renato Penna Francisco José Nogueira Célio E. D. 《Journal of gastrointestinal cancer》1986,1(5-6):399-406
Journal of Gastrointestinal Cancer - The authors observed 329 consecutive cases of chronic calcifying pancreatitis (CCP) from January 1963 to January 1986. Alcoholism was the etiological agent in... 相似文献
5.
Ketai LH; Williamson MR; Telepak RJ; Levy H; Koster FT; Nolte KB; Allen SE 《Radiology》1994,191(3):665
6.
Mário Martins Oliveira Nogueira da Silva Ana Teresa Timóteo Joana Feliciano Lídia de Sousa Sofia Santos Fernando Marques Rui Ferreira 《Revista portuguesa de cardiologia》2007,26(7-8):691-702
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
7.
Andr ia Kist Fernandes Felipe Mallmann Ana Maria Pasquali Steinhorst Fernando Lopes Nogueira Eduardo Mü ller vila Dumitriu Zunino Saucedo Francisco Juchem Machado Marcelo Greg rio Raymundi S rgio Saldanha Menna Barreto Paulo de Tarso Roth Dalcin 《The Journal of asthma》2003,40(6):683-690
Asthma patients that depend on emergency department (ED) services are generally considered to have extremely poor disease control and prognosis. It is important to identify characteristics related to poor disease control and frequent visits to the ED to apply appropriate clinical management. This study comprised a cross-sectional survey of consecutive patients with asthma exacerbation (age ≥12 years) presenting at the adult ED of a large, tertiary care, university-affiliated hospital over a 2-month period. The frequent visitors (FV) were defined by ≥3 visits to the ED in the preceding year, and the occasional visitors (OV) by ≤2 visits. Eighty-six patients (61 females and 25 males) were included in the study (mean age 38 ± 18 years). Of these patients, 51.2% were FV and 48.8% were OV. Sixty-nine percent had annual income lower than A$3000 and 66.3% had ≤8 years of the formal education. Only 18.6% had used inhaled corticosteroids, 79.1% identified the asthma attack severity, 70.9% increased or initiated inhaled β-agonist, 20.9% increased or initiated steroid therapy, and 55.8% had an asthma action plan for attack. The number of hospital admissions in past year (OR 4.3, P = .02), use of home nebulizer (OR 3.6, P = .05) and the lack of a written asthma action plan (OR 3.3, P = .03) were independently associated with frequent visits to the ED. We conclude that a substantial proportion of the patients that visit the ED are FV. These patients are more likely to have hospital admission in the past year, to use a home nebulizer, and to lack a written asthma action plan. They should be considered the most important target for asthma education. 相似文献
8.
9.
10.