全文获取类型
收费全文 | 3342篇 |
免费 | 205篇 |
国内免费 | 83篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 140篇 |
妇产科学 | 90篇 |
基础医学 | 458篇 |
口腔科学 | 34篇 |
临床医学 | 440篇 |
内科学 | 604篇 |
皮肤病学 | 39篇 |
神经病学 | 259篇 |
特种医学 | 421篇 |
外国民族医学 | 3篇 |
外科学 | 403篇 |
综合类 | 66篇 |
一般理论 | 2篇 |
预防医学 | 169篇 |
眼科学 | 55篇 |
药学 | 259篇 |
肿瘤学 | 172篇 |
出版年
2023年 | 21篇 |
2021年 | 43篇 |
2020年 | 30篇 |
2019年 | 42篇 |
2018年 | 77篇 |
2017年 | 53篇 |
2016年 | 39篇 |
2015年 | 39篇 |
2014年 | 64篇 |
2013年 | 87篇 |
2012年 | 150篇 |
2011年 | 133篇 |
2010年 | 75篇 |
2009年 | 92篇 |
2008年 | 112篇 |
2007年 | 170篇 |
2006年 | 111篇 |
2005年 | 124篇 |
2004年 | 115篇 |
2003年 | 131篇 |
2002年 | 89篇 |
2001年 | 91篇 |
2000年 | 92篇 |
1999年 | 88篇 |
1998年 | 92篇 |
1997年 | 90篇 |
1996年 | 70篇 |
1995年 | 72篇 |
1994年 | 51篇 |
1993年 | 40篇 |
1992年 | 69篇 |
1991年 | 71篇 |
1990年 | 64篇 |
1989年 | 95篇 |
1988年 | 72篇 |
1987年 | 65篇 |
1986年 | 66篇 |
1985年 | 84篇 |
1984年 | 63篇 |
1983年 | 31篇 |
1982年 | 48篇 |
1981年 | 34篇 |
1980年 | 35篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 43篇 |
1976年 | 43篇 |
1975年 | 27篇 |
1974年 | 25篇 |
1973年 | 21篇 |
排序方式: 共有3630条查询结果,搜索用时 15 毫秒
1.
Relapsing polychondritis is an autoimmune disease that affects all body cartilages. The disease may also involve the audio-vestibular system, usually bilaterally. Most of the reported cases were adults 20 years old or more. This is a case report of a 12-year-old girl with unilateral sensorineural hearing loss, and a review of the literature. 相似文献
2.
Coronary artery bypass grafts: visualization with MR imaging 总被引:1,自引:0,他引:1
3.
Depressive Symptoms and Associated Factors in Children With Attention Deficit Hyperactivity Disorder
Nancy LeBlanc PhD RN Diane Morin PhD RN 《Journal of child and adolescent psychiatric nursing》2004,17(2):49-55
PROBLEM: To compare depressive symptoms in children with attention deficit hyperactivity disorder (ADHD) to those in healthy children, and to explore the influence of individual and family factors on level of depression. METHODS: Individual interviews with 68 children, ages 7 to 12 years, in order to complete the Children's Depression Inventory. FINDINGS: Children with ADHD reported significantly more depressive symptoms than did children without ADHD; 14.7% of children with ADHD reached the threshold of a 19 point score, which suggests clinical depression. No significant effects of individual and family factors on level of depression were found. CONCLUSIONS: Children with ADHD are more inclined to experience depressive symptoms than are healthy children. To plan appropriate interventions, nurses evaluating and working with children with ADHD should always consider a possible coexistence of depressive symptoms. 相似文献
4.
D. Chemla P. Démolis M. Thyrault D. Annane Y. Lecarpentier and JF Giudicelli 《Fundamental & clinical pharmacology》1996,10(4):393-399
Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (Vm ) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (Gmax = +dV/dtmax ). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, Gmax was of a similar magnitude (551 ±30 and 555 ± 44 cm/s2 , respectively) despite major differences in the respective D, Vm , Q and R values. In neither artery was there a relationship between Gmax and either resting Q or R. At the brachial artery level, Gmax was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between Gmax and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow. 相似文献
5.
6.
Jean-Francois Morin M.D. Bergez F. Mistry M.D. FRCPC Lisa Knowlton M.D. 《Journal of cardiac surgery》2007,22(4):356-358
Abstract In this case report we describe a situation where despite a normal TEE exam immediately postcardiopulmonary bypass, there was no flow in the left internal mammary artery graft to the left anterior descending artery. This was picked up by coronary Doppler and subsequently repaired. 相似文献
7.
J Brent Richards William D Leslie Lawrence Joseph Kerry Siminoski David A Hanley Jonathan D Adachi Jacques P Brown Suzanne Morin Alexandra Papaioannou Robert G Josse Jerilynn C Prior K Shawn Davison Alan Tenenhouse David Goltzman 《Journal of bone and mineral research》2007,22(2):228-234
The impact of clinical risk factor-based absolute risk methods on the prevalence of high risk for osteoporotic fracture is unknown. We applied absolute risk methods to 6646 subjects and found that the prevalence of elderly women deemed to be at high risk increased substantially, whereas the overall prevalence was highly dependent on the threshold used to designate high risk. INTRODUCTION: Many groups have advocated using absolute risk methods that incorporate clinical risk factors to target patients for osteoporosis therapy. We examined how the application of such absolute risk classification systems influences the prevalence of those considered to be at high risk for osteoporotic fracture and compared these systems to one based solely on BMD. MATERIALS AND METHODS: Using 6646 subjects from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective, randomly selected, population-based cohort, we assessed three different systems for determining prevalence of high risk for osteoporotic fracture: a BMD-based system; a simplified risk factor system incorporating age, sex, BMD, and two clinical risk factors; and a comprehensive system, incorporating age, sex, BMD, and seven clinical risk factors. The 10-year absolute risks of incident fragility fracture were compared across systems using three different high-risk thresholds. RESULTS: The prevalence of a T score < or = -2.5 was 18.8% (95% CI: 17.7-19.9%) in women and 3.9% (95% CI: 3.0-4.7%) in men. Using a 15% 10-year risk of fracture threshold, the prevalence of women at high risk increased to 46.9% (95% CI: 45.4-48.4) and 42.5% (95% CI: 41.1-43.9) when the comprehensive and simplified risk factor classification systems were used, respectively. Using a 25% 10-year absolute risk threshold, the prevalence of high risk was similar to that of the BMD-based system, whereas the 20% threshold gave intermediate rates. All thresholds analyzed resulted in an increased prevalence of older women at high risk for fracture, whereas only the 15% 10-year risk of fracture threshold resulted in an increase in the prevalence of men at high risk. CONCLUSIONS: The application of risk factor-based systems results in an increased prevalence of older women at high risk. The prevalence of individuals at high risk may increase with changes to the methods used to determine those who are eligible for therapy. These data have important implications for the pattern of care and costs of treating osteoporotic fractures. 相似文献
8.
9.
Michele Morin Doody Martha S. Linet Andrew G. Glass Gary D. Friedman Linda M. Pottern John D. Boice Jr Joseph F. Fraumeni Jr 《Cancer causes & control : CCC》1992,3(5):449-456
The role of selected prior medical conditions in the etiology of hematopoietic malignancies was examined in a case-control study of members of two regional branches of the Kaiser Permanente Medical Care Program (USA). Past history of chronic infectious, autoimmune, allergic, and musculoskeletal disorders was abstracted from medical records for leukemia (n = 299), non-Hodgkin's lymphoma (NHL, n = 100), and multiple myeloma (n = 175) cases and matched controls (n = 787). Little difference was found between cases and controls for most of the chronic conditions evaluated, including sinusitis, carbuncles, urinary tract infections, pelvic infections, herpes zoster, asthma, rheumatoid arthritis, psoriasis, bursitis, and gout. Only three statistically significant elevated risks were found, i.e., with combined disc disease myeloma among patients with prior eczema and disk and other musculoskeletal conditions, and NHL following tuberculosis. Only two of these associations showed consistent patterns by sex and geographic region (myeloma with eczema and with musculoskeletal conditions). While prior history of eczema and musculoskeletal conditions may slightly increase risk of myeloma, this study provided little if any support for an association of chronic infectious, autoimmune, allergic, and musculoskeletal conditions with subsequent occurrence of the leukemias or NHL. Additionally, these data did not support a role for chronic antigenic stimulation, as defined in previous epidemiologic studies, in the etiology of hematopoietic malignancies.Ms Doody and Drs Linet, Pottern, Boice, and Fraumeni are with the Epidemiology and Biostatistics Program, National Cancer Institute. Dr Glass is with the Kaiser Permanente Medical Care Program, Northwest Region, Portland, Oregon, USA. Dr Friedman is with the Kaiser Permanente Medical Care Program, Northern California Region, Oakland, California, USA. Address correspondence to Ms Doody, Radiation Epidemiology Branch, National Cancer Institute, Executive Plaza North, Room 408, Bethesda, MD 20892, USA. This research was supported in part by National Cancer Institute contracts NO1-CP-01047, NO1-CP-01054, NO1-CP-11009, NO1-CP-11037, NO1-CP-31035, and NO1-CP-61006. 相似文献
10.
It has recently been shown that it is possible to discriminate accurately among myoelectric signals underlying different muscle
contraction types, specifically elbow flexion and extension and forearm pronation and supination. It was reported that once
a number of distinctive features had been extracted from the myoelectric signals, a neural network could be trained to distinguish
the contraction types with an impressively high accuracy. In the present paper, we show that a technique known as parallel
cascade identification can be used to construct classifiers that can also accurately, differentiate the contraction types.
The use of parallel cascades has the benefit of dispensing with the need for feature extraction, so that raw myoelectric signal
data can be used directly. In addition, very little data are required to train the parallel cascades to distinguish accurately
novel incoming myoelectric signals. Results of using parallel cascades to distinguish foream pronation, supination, and elbow
flexion are presented. 相似文献