全文获取类型
收费全文 | 389726篇 |
免费 | 48408篇 |
国内免费 | 3291篇 |
专业分类
耳鼻咽喉 | 7518篇 |
儿科学 | 11637篇 |
妇产科学 | 6857篇 |
基础医学 | 35837篇 |
口腔科学 | 5971篇 |
临床医学 | 50297篇 |
内科学 | 96870篇 |
皮肤病学 | 10555篇 |
神经病学 | 37886篇 |
特种医学 | 14322篇 |
外国民族医学 | 11篇 |
外科学 | 76458篇 |
综合类 | 3675篇 |
现状与发展 | 72篇 |
一般理论 | 318篇 |
预防医学 | 27801篇 |
眼科学 | 9699篇 |
药学 | 17736篇 |
6篇 | |
中国医学 | 367篇 |
肿瘤学 | 27532篇 |
出版年
2023年 | 5661篇 |
2022年 | 3352篇 |
2021年 | 8168篇 |
2020年 | 8811篇 |
2019年 | 7220篇 |
2018年 | 12820篇 |
2017年 | 11271篇 |
2016年 | 12716篇 |
2015年 | 13640篇 |
2014年 | 23046篇 |
2013年 | 26351篇 |
2012年 | 22997篇 |
2011年 | 23879篇 |
2010年 | 20258篇 |
2009年 | 22669篇 |
2008年 | 21942篇 |
2007年 | 21092篇 |
2006年 | 23296篇 |
2005年 | 20649篇 |
2004年 | 18945篇 |
2003年 | 16824篇 |
2002年 | 15947篇 |
2001年 | 5662篇 |
2000年 | 4393篇 |
1999年 | 5251篇 |
1998年 | 6457篇 |
1997年 | 5758篇 |
1996年 | 5299篇 |
1995年 | 5054篇 |
1994年 | 3568篇 |
1993年 | 3051篇 |
1992年 | 2560篇 |
1991年 | 2473篇 |
1990年 | 1984篇 |
1989年 | 2078篇 |
1988年 | 1928篇 |
1987年 | 1741篇 |
1986年 | 1784篇 |
1985年 | 1642篇 |
1984年 | 1731篇 |
1983年 | 1602篇 |
1982年 | 1851篇 |
1981年 | 1695篇 |
1980年 | 1494篇 |
1979年 | 1001篇 |
1978年 | 1057篇 |
1977年 | 1018篇 |
1976年 | 815篇 |
1975年 | 736篇 |
1974年 | 690篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Background: Melatonin is gaining popularity as a sedative agent with children. This study sought to characterise this practice more precisely as well as examine aspects of its safety and efficacy in order to develop treatment guidelines.
Method: Postal surveys of two groups of psychiatrists: generic child psychiatrists and psychiatrists who regularly treat learning disabled children.
Results: Both groups (all of the specialists and 81% of the non-specialists) reported regular but not frequent use of melatonin in their usual practice, mostly for night-settling sleep problems refractory to behavioural modification strategies, commonly in the context of neurodevelopmental disability (especially autism). Treatment was described as being 'usually successful' and side-effects were highly infrequent and mild in nature. Variations in most prescribing practices were identified (dosage, timing).
Conclusions: Melatonin appears to represent a useful and relatively safe drug when used in specific circumstances; however, the evidence-base underpinning its use, particularly over the long-term, remains modest. Thus caution and clinical audit of practice is required. 相似文献
Method: Postal surveys of two groups of psychiatrists: generic child psychiatrists and psychiatrists who regularly treat learning disabled children.
Results: Both groups (all of the specialists and 81% of the non-specialists) reported regular but not frequent use of melatonin in their usual practice, mostly for night-settling sleep problems refractory to behavioural modification strategies, commonly in the context of neurodevelopmental disability (especially autism). Treatment was described as being 'usually successful' and side-effects were highly infrequent and mild in nature. Variations in most prescribing practices were identified (dosage, timing).
Conclusions: Melatonin appears to represent a useful and relatively safe drug when used in specific circumstances; however, the evidence-base underpinning its use, particularly over the long-term, remains modest. Thus caution and clinical audit of practice is required. 相似文献
994.
Hao Wu Colin Webber Carmen Otero Fuentes Robert Bensen Karen Beattie Jonathan D Adachi Xiaoming Xie Farhang Jabbari David R Levy 《Journal l'Association canadienne des radiologistes》2007,58(3):167-175
OBJECTIVES: 1) To assess, with a peripheral magnetic resonance imaging system (pMRI), the prevalence of bony and soft tissue abnormalities in the knee joints of normal subjects, osteoarthritis (OA) patients, and individuals who have suffered an anterior cruciate ligament (ACL) rupture; and 2) to compare the prevalence among groups. METHODS: Magnetic resonance (MR) images of 28 healthy, 32 OA, and 26 ACL damaged knees were acquired with a 1.0-T pMRI system. Two radiologists graded the presence and severity of 9 MR image features: cartilage degeneration, osteophytes, subchondral cyst, bone marrow edema, meniscal abnormality, ligament integrity, loose bodies, popliteal cysts, and joint effusion. RESULTS: Ten of 28 healthy (35.7%), 24 of 26 ACL (92.3%), and all OA knees (100%) showed prevalent cartilage defects; 5 healthy (17.9%), 20 ACL (76.9%), and all OA knees (100%) had osteophytes; and 9 normal (32.1%), 21 ACL (80.8%), and 29 OA knees (90.6%) had meniscal abnormalities. One-half of the knees in the OA group (16 of 32, 50%) had subchondral cysts, and almost one-half had bone marrow edema (15 of 32, 46.9%). These features were not common in the ACL group (7.7%, and 11.5%, respectively) and were not observed in healthy knees. The OA group had the most severe cartilage defects, osteophytes, bone marrow edema, subchondral cysts, and meniscal abnormalities; the ACL group showed more severe cartilage defects, osteophytes, and meniscal abnormalities than did normal subjects. CONCLUSION: The results suggest that knees that have sustained ACL damage have OA-like reatures; most subjects (19 of 26, 73.1%) could be identified as in the early stage of OA. The prominent abnormalities present in ACL-damaged knees are cartilage defects, osteophytes, and meniscal abnormalities. 相似文献
995.
996.
Darren S Parsons David A Reaveley Darrell V Pavitt Madhukar Misra Edwina A Brown 《Nephrology, dialysis, transplantation》2003,18(9):1848-1853
BACKGROUND: Studies have reported an increase in median Lipoprotein (Lp) (a) in patients with high molecular weight (HMW) apolipoprotein (apo) (a) isoforms and renal impairment. Some studies identify Lp (a) levels as a risk factor for vascular disease in renal failure whilst others have demonstrated an association with apo (a) isoform type and vascular disease. METHODS: A total of 239 patients at end-stage renal failure (ESRF) were studied prior to the initiation of dialysis. Blood was taken for Lp (a) levels and apo (a) isoforms. Clinical vascular disease (CVD) was assessed on the basis of clinical history and Rose questionnaire. The control group for Lp (a) levels consisted of 228 healthy volunteers. RESULTS: Despite a higher median Lp (a) level in those with HMW isoforms, 30% of patients had Lp (a) levels <10 mg/dl. Overall, 49% patients were identified as having CVD. Diabetes, smoking history and Lp (a) levels were significantly associated with CVD in logistic regression analysis, although when patients with low molecular weight (LMW) and HMW isoforms were analysed separately, Lp (a) levels were not significantly associated with CVD in those with LMW isoforms. The rates of CVD in those with HMW isoform and low Lp (a) levels were significantly lower than those with HMW isoforms and elevated Lp (a) levels, 34 vs 57% (P < 0.01). CONCLUSIONS: Although median Lp (a) levels in those patients at ESRF with HMW isoforms are higher than controls, in a third of such patients Lp (a) levels remain relatively low. These patients have lower rates of CVD than those with high levels of Lp (a). 相似文献
997.
Rolf-Dieter Kortmann MD 《Strahlentherapie und Onkologie》2004,180(4):245-245
998.
Sami R Achem MD Alexander Klaus MD Ronald A Hinder MD PhD Kenneth R DeVault MD 《The American journal of medicine》2004,116(10):717-718
999.
1000.
Christopher L. Knight MD Henry A. Sakowski MD Bruce L. Houghton MD Mary B. Laya MD MPH Dawn E. DeWitt MD MSc 《Journal of general internal medicine》2004,19(5P2):594-598
The World Wide Web creates new challenges and opportunities for medical educators. Prominent among these are the lack of consistent standards by which to evaluate web-based educational tools. We present the instrument that was used to review web-based innovations in medical education submissions to the 2003 Society of General Internal Medicine (SGIM) national meeting, and discuss the process used by the SGIM web-based clinical curriculum interest group to develop the instrument. The 5 highest-ranked submissions are summarized with commentary from the reviewers. 相似文献