全文获取类型
收费全文 | 14498篇 |
免费 | 1197篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 141篇 |
儿科学 | 414篇 |
妇产科学 | 268篇 |
基础医学 | 1910篇 |
口腔科学 | 399篇 |
临床医学 | 1780篇 |
内科学 | 2997篇 |
皮肤病学 | 166篇 |
神经病学 | 1638篇 |
特种医学 | 731篇 |
外科学 | 2285篇 |
综合类 | 203篇 |
一般理论 | 18篇 |
预防医学 | 751篇 |
眼科学 | 256篇 |
药学 | 831篇 |
中国医学 | 14篇 |
肿瘤学 | 943篇 |
出版年
2023年 | 89篇 |
2022年 | 139篇 |
2021年 | 485篇 |
2020年 | 261篇 |
2019年 | 341篇 |
2018年 | 412篇 |
2017年 | 320篇 |
2016年 | 439篇 |
2015年 | 483篇 |
2014年 | 594篇 |
2013年 | 692篇 |
2012年 | 1063篇 |
2011年 | 970篇 |
2010年 | 589篇 |
2009年 | 523篇 |
2008年 | 808篇 |
2007年 | 748篇 |
2006年 | 686篇 |
2005年 | 676篇 |
2004年 | 561篇 |
2003年 | 563篇 |
2002年 | 421篇 |
2001年 | 228篇 |
2000年 | 238篇 |
1999年 | 235篇 |
1998年 | 139篇 |
1997年 | 113篇 |
1996年 | 65篇 |
1995年 | 74篇 |
1994年 | 70篇 |
1993年 | 63篇 |
1992年 | 167篇 |
1991年 | 176篇 |
1990年 | 169篇 |
1989年 | 176篇 |
1988年 | 153篇 |
1987年 | 177篇 |
1986年 | 153篇 |
1985年 | 130篇 |
1984年 | 119篇 |
1983年 | 103篇 |
1981年 | 66篇 |
1980年 | 67篇 |
1979年 | 116篇 |
1978年 | 81篇 |
1977年 | 61篇 |
1975年 | 71篇 |
1974年 | 72篇 |
1973年 | 69篇 |
1972年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
71.
72.
A paralysis of the left vocal cord was seen by laryngoscopy in a 3-days-old boy with inspiratory stridor. A ductus aneurysm was established by angiocardiography, which was believed to be the cause of the vocal cord paralysis. Within 8 days after the angiocardiography the aneurysm became smaller and the stridor disappeared. Twelfth months later the control-angiocardiography showed the total obliteration of the ductal aneurysm. 相似文献
73.
S. J. Edmondston Dr K. P. Singer R. E. Day R. I. Price P. D. Breidahl 《Osteoporosis international》1997,7(2):142-148
The estimation of vertebral fracture risk in individuals with suspected osteopenia is commonly based on measurements of lumbar spine bone density. The efficacy of vertebral size and deformity, as assessed by vertebral morphometry, in the prediction of fractures has been less studied. In an ex vivo investigation the regional relationships between vertebral size, vertebral deformity, bone density and compressive strength throughout the thoracolumbar spine were examined. In 16 vertebral columns (T1–L5) the bone mineral content (BMC) and bone mineral density (BMD) of each segment were measured using lateral projection dual-energy X-ray absorptiometry, and the vertebral cancellous density (VCD) and mid-vertebral cross-sectional area (CSA) measured using quantitative computed tomography. Vertebral body heights were determined from mid-sagittal CT scans, and vertical height ratios calculated for each segment. The failure load and failure stress of the isolated vertebral bodies were determined using a material testing device. Separate analyses were performed for the upper (T1–4), middle (T5–8) and lower (T9–12) thoracic, and lumbar (L1–5) segments. In all regions, failure load was strongly correlated with BMD (r=0.82–0.86), moderately correlated with VCD (r=0.60–0.71) and vertebral height (r=0.22–0.49), and poorly correlated with the height ratios (r=0.04–0.33). Failure stress was best predicted by BMD (r=0.73–0.78) and VCD (r=0.70–0.78) but was poorly correlated with all morphometric variables (r=0.01–0.33). The segmental correlations between BMD and VCD ranged fromr=0.49 tor=0.79. For all regions, BMD and VCD were included in the stepwise regression models for predicting failure load and failure stress. Either the mid-vertebral height or CSA were included in all the failure load models, while mid-vertebral height was included in only one of the failure stress models. The results suggest that vertebral deformity and size (as assessed by vertebral morphometry) make only a minor contribution to the prediction of vertebral strength additional to that provided by bone densitometry alone. The consistent regional relationships between variables appear to support the practice of global fracture risk assessment based on lumbar spine densitometry. 相似文献
74.
J S Carey R A Cukingnan L K Singer 《The Journal of thoracic and cardiovascular surgery》1992,103(1):108-115
The effect of increasing age on quality of life, survival, and risk of reoperation was studied in 2479 patients followed up prospectively 2 to 20 years after myocardial revascularization. Quality of life was determined from annual questionnaires, which we used to calculate a health status index from the patient's symptomatic status and subjective response to the operation, which was graded between zero and 1.00 (asymptomatic). Four age groups were studied: age 49 years or less (AG40), 50 to 59 years (AG50), 60 to 69 years (AG60), and 70 years or older (AG70). Associated problems (left ventricular aneurysm, valve disease, acute myocardial infarction) necessitating treatment were present in 17% (61/361) of AG40 patients, 19% (165 of 859) of AG50 patients, 23% (213/927) of AG60 patients, and 31% (102/332) of AG70 patients. The hospital mortality rate was higher in older patients undergoing combined procedures but not in patients undergoing coronary bypass grafts only. Probability of survival and health status indexes were calculated excluding patients with valve disease and cardiogenic shock. Probability of survival was significantly better (p less than 0.001 by the Wilcoxon test) in patients less than age 60 than in those 60 years or older, but in patients with an ejection fraction greater than or equal to 0.40, probability of survival at 12 years was 0.64 (age less than 60) versus 0.62 (age greater than or equal to 60). The actuarial risk of reoperation, calculated as the difference between probability of survival and probability of survival without reoperation, progressively increased in younger patients but not in patients aged 60 years or older. At 15 years, the reoperation rates were 26% (AG40), 14% (AG50), 5% (AG60), and 7% (AG70). Mean health status index for years 1 to 5 was 0.85 in AG40 patients, 0.84 in AG50 patients, 0.89 in AG60 patients, and 0.90 in AG70 patients; for years 6 to 10, 0.81, 0.80, 0.86, and 0.89; and for years 11 to 15, 0.77, 0.78, 0.84, and 0.84, respectively. Thus quality of life after myocardial revascularization is better, improvement lasts longer, and reoperation rate is less in patients aged 60 years or older. 相似文献
75.
76.
Sociodemographic and behavioral characteristics of HIV antibody-positive blood donors. 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《American journal of public health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P D Cleary E Singer T F Rogers J Avorn N Van Devanter S Soumerai S Perry J Pindyck 《American journal of public health》1988,78(8):953-957
This paper describes the sociodemographic and behavioral characteristics of 173 blood donors who were confirmed by Western blot tests to have antibodies to human immunodeficiency virus (HIV), the etiologic agent for acquired immunodeficiency syndrome (AIDS). Seropositive donors were predominantly young, unmarried, and male, and major risk factors could be identified for almost all donors. However, more than 20 per cent of the study participants were women, and many participants were not aware that they were at risk of infection. The heterogeneity of the study population, the lack of awareness among many subjects of risk factors and self-exclusion procedures, and the high level of distress among many subjects after notification, emphasize the need for intensive, well-designed education and support programs. 相似文献
77.
78.
There is some controversy over the treatment of acromioclavicular injuries. The use of the Rockwood classification as the basis for decisions on whether operative or nonoperative treatment is indicated is discussed critically, and the authors' preferred operative technique is described and illustrated by examples. We treat injuries classified according to the Rockwood classification as types I and II with conservative methods. In type III injuries the patient's age, job and free time activities determine whether or not surgery is indicated. In the case of type IV or type VI injuries we always perform temporary internal fixation of the acromioclavicular joint, using transarticular K-wire fixation or hookplate osteosynthesis. Satisfactory results of both operative and nonoperative treatment are reported in the literature. The authors' own results are presented. 相似文献
79.
Psychophysical measurements were carried out with a microcomputer-controlled matrix of 32 X 32 light emitting diodes to determine temporal parameters of figure-ground separation processes. The task was to detect a figure that was dispersed in time. Between each two figure elements n noise elements were interspersed. The results of these experiments indicate that the discrimination of figures hidden in dynamic noise is possible even if figure elements are dispersed in time over several hundred milliseconds. The maximal dispersion time still compatible with figure discrimination (Tmax) depends critically on the number n of interspersed noise elements, on the subject's expectancy and on the number of elements used for the generation of the figure. For simple figures such as triangles Tmax could be as long as 1.5 sec when n was 4. Our experimental results suggest that the neuronal representation of the briefly displayed (less than 6 msec) pattern elements outlasts their physical presence by at least 400 msec. This persistence of neuronal representations must occur at a level of processing where retinotopy is still preserved, since the only cue for figure-ground discrimination is the difference in the local density of figure and noise elements. 相似文献
80.
Bakamjian introduced the deltopectoral skin flap in 1965, and thereafter it was used extensively for reconstructive surgery of the head and neck. Flap failure rates of 10% to 25% were reported, necessitating the development of alternative methods of reconstruction and eventually relegating the flap to historical references. Since 1991, we have used the deltopectoral flap in 24 patients for reconstruction after head and neck tumor surgery. Simple technical modifications have been used to enhance the reliability of this flap, with no observed failures or even partial flap loss. The deltopectoral flap remains a versatile and reliable tissue source that can be used simultaneously with the pectoralis major myocutaneous flap for a variety of complex head and neck reconstructions. Laryngoscope, 106:1230-1233, 1996 相似文献