全文获取类型
收费全文 | 216184篇 |
免费 | 44968篇 |
国内免费 | 345篇 |
专业分类
耳鼻咽喉 | 3615篇 |
儿科学 | 8614篇 |
妇产科学 | 3667篇 |
基础医学 | 34039篇 |
口腔科学 | 9326篇 |
临床医学 | 20968篇 |
内科学 | 56848篇 |
皮肤病学 | 11197篇 |
神经病学 | 24185篇 |
特种医学 | 5335篇 |
外国民族医学 | 1篇 |
外科学 | 30645篇 |
综合类 | 781篇 |
一般理论 | 70篇 |
预防医学 | 18264篇 |
眼科学 | 4235篇 |
药学 | 14958篇 |
中国医学 | 1659篇 |
肿瘤学 | 13090篇 |
出版年
2023年 | 1053篇 |
2022年 | 1099篇 |
2021年 | 4618篇 |
2020年 | 6718篇 |
2019年 | 14074篇 |
2018年 | 14808篇 |
2017年 | 13864篇 |
2016年 | 14341篇 |
2015年 | 14561篇 |
2014年 | 15134篇 |
2013年 | 17567篇 |
2012年 | 14032篇 |
2011年 | 14608篇 |
2010年 | 13986篇 |
2009年 | 9110篇 |
2008年 | 10571篇 |
2007年 | 10027篇 |
2006年 | 9424篇 |
2005年 | 9047篇 |
2004年 | 8142篇 |
2003年 | 7677篇 |
2002年 | 7289篇 |
2001年 | 4938篇 |
2000年 | 5518篇 |
1999年 | 3856篇 |
1998年 | 708篇 |
1997年 | 482篇 |
1996年 | 456篇 |
1995年 | 365篇 |
1994年 | 283篇 |
1992年 | 1438篇 |
1991年 | 1184篇 |
1990年 | 1047篇 |
1989年 | 854篇 |
1988年 | 702篇 |
1987年 | 690篇 |
1986年 | 685篇 |
1985年 | 581篇 |
1984年 | 439篇 |
1983年 | 327篇 |
1979年 | 369篇 |
1975年 | 304篇 |
1974年 | 339篇 |
1973年 | 376篇 |
1972年 | 316篇 |
1971年 | 326篇 |
1970年 | 306篇 |
1969年 | 305篇 |
1968年 | 277篇 |
1967年 | 254篇 |
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
21.
22.
Jorge Guardado Carlos Cotrim Otília Sim?es Sofia Almeida Mário Ialá Luís Lopes Hélder Pereira Manuel Carrageta 《Revista portuguesa de cardiologia》2006,25(4):409-415
INTRODUCTION: Transesophageal echocardiography (TEE) has become increasingly useful in the study of patients with suspected pulmonary thromboembolism. OBJECTIVE: The aim of this study was to prospectively evaluate the usefulness of TEE in the study of the distal part of the left pulmonary artery (LPA) as well as the influence of this procedure on total echocardiographic exam duration. METHODOLOGY: A prospective study in two groups of consecutive patients referred for TEE with a one- year interval between evaluation of Group A: 33 patients, 17 male, mean age 54 +/- 24 years, and Group B: 42 patients, 20 male, mean age 48 +/- 27 years (p = NS). The procedure was considered long when it took more than 3 min to evaluate the distal part of the LPA. RESULTS: In group A we were able to visualize the distal part of the LPA in 24 patients (73%) without significant prolongation of total exam duration in 16 patients (48% of group A). In one of the patients with suspected pulmonary thromboembolism thrombi were only observed in the distal part of the LPA. In group B we were able to visualize the distal part of the LPA in 36 patients (86%) without significant prolongation of total exam duration in 26 patients (61% of group B). CONCLUSIONS: 1. Visualization of the distal part of the LPA was possible in more patients, and with TEE time prolongation in less patients, in group B. These differences can be accounted for by the training of the operator in this technique. 2. The importance of visualization of this part of the LPA in guiding treatment in the subset of patients with pulmonary thromboembolism confirms the usefulness of this specific procedure. 相似文献
23.
Abstract: Background: Identification of risk drinking in expectant fathers may be helpful as an important part of efforts to minimize maternal alcohol use, and as an opportunity to inform them about a problematic practice during a critical developmental stage for the couple. The purpose of this study was to evaluate the T‐ACE screening questionnaire, which asks about t olerance to alcohol, being a nnoyed by other's comments about drinking, attempts to c ut down, and having a drink first thing in the morning (“ e ye‐opener”), in the male partners of pregnant women who themselves were T‐ACE positive. Methods: Two hundred fifty‐four male partners were asked to complete the T‐ACE embedded in a health survey, the Alcohol Use Disorders Identification Test (AUDIT), and other questions about their alcohol use in the past 30 days when their pregnant partners had a median gestation of 11.5 weeks (T1). After delivery, male partners again completed the T‐ACE and quantity‐frequency questions (T2). The predictive ability of the T‐ACE and AUDIT was compared, using risk drinking (>4 drinks/day or >14 drinks/week) as the criterion standard. Results: A substantial minority of male partners had risk drinking, 31 percent at T1 and 25 percent at T2. Although the AUDIT was better than the T‐ACE as an independent predictor of risk drinking, the latter was most accurate when the tolerance threshold exceeded 2 drinks, the same established for pregnant women. The sensitivity (T1 = 84.6%, T2 = 82.8%) and specificity (T1 = 43.8%, T2 = 51.1%) of the T‐ACE at this threshold compared favorably with those of the AUDIT at the standard cut point of 8. Conclusions: The T‐ACE may be a practical way for clinicians to identify risk drinking in both pregnant women and expectant fathers. (BIRTH 33:2 June 2006) 相似文献
24.
25.
26.
27.
The present authors investigated the excretion, distribution and pharmacokinetics of the novel potential antirheumatic agent flobufen and its active metabolite after p.o. and i.v. doses of 2, 10 and 50 mg/kg administered to rats. The drug is resorbed well from the digestive tract and mostly it is metabolized to the principal metabolite M, which is only slowly excreted from the organism mainly by renal clearance. Within the whole dose range the kinetics of the drug is linear. Binding of flobufen and M to proteins is high (95-99%). The highest concentrations of radioactive metabolites (mostly M) were found in the plasma, liver, lungs, kidneys, connective tissue and inflammatory foci. The penetration of metabolites through the placenta and excretion in human milk are relatively important. 相似文献
28.
29.
30.
Melatonin, a pineal hormone, released photoperiodically, was administered systemically in rats, previously implanted with semimicroelectrodes into six different brain structures. The multiunit electrical activity of these structures was recorded for 10 min before and 60 min after melatonin administration in unanesthetized, freely moving rats. Different melatonin doses (100, 200, 500, and 1000 micrograms/kg) produced changes in the electrical activity of all tested structures. However, amygdala, rostral hypothalamus and mesencephalic reticular formation showed the most important changes. The main effect induced by melatonin was a dose-related decrease of the spontaneous electrical activity. The significance of these effects is discussed within the context of the behavioral and endocrinological effects of melatonin. 相似文献