首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1249篇
  免费   67篇
  国内免费   3篇
耳鼻咽喉   7篇
儿科学   54篇
妇产科学   6篇
基础医学   100篇
口腔科学   46篇
临床医学   98篇
内科学   142篇
皮肤病学   86篇
神经病学   56篇
特种医学   70篇
外科学   178篇
综合类   283篇
一般理论   1篇
预防医学   62篇
眼科学   6篇
药学   99篇
  1篇
肿瘤学   24篇
  2023年   5篇
  2022年   5篇
  2021年   9篇
  2020年   8篇
  2019年   6篇
  2018年   12篇
  2017年   7篇
  2016年   14篇
  2015年   31篇
  2014年   31篇
  2013年   40篇
  2012年   38篇
  2011年   39篇
  2010年   77篇
  2009年   53篇
  2008年   62篇
  2007年   64篇
  2006年   87篇
  2005年   54篇
  2004年   70篇
  2003年   47篇
  2002年   45篇
  2001年   45篇
  2000年   42篇
  1999年   31篇
  1998年   31篇
  1997年   39篇
  1996年   39篇
  1995年   21篇
  1994年   24篇
  1993年   15篇
  1992年   22篇
  1991年   5篇
  1990年   7篇
  1989年   11篇
  1988年   18篇
  1987年   15篇
  1986年   17篇
  1985年   11篇
  1984年   15篇
  1983年   15篇
  1982年   16篇
  1981年   5篇
  1980年   5篇
  1979年   7篇
  1978年   9篇
  1976年   10篇
  1972年   6篇
  1970年   4篇
  1968年   4篇
排序方式: 共有1319条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: The present study was aimed to define the gender ratio, familial occurrence, age of onset, precipitating factors, clinical types, nail and joint involvement of psoriasis in childhood and adolescence in Turkey. METHODS: A total of 61 children with psoriasis under 18 years old were evaluated retrospectively, for age, gender, age of disease onset, family history, concomitant disease, the clinical type of psoriasis, clinical localization, nail and joint involvement and treatment modalities. RESULTS: Of the patients, 23 (37.70%) were boys and 38 (62.30%) were girls. Mean age was 9.28 +/- 4.02 years in girls and 11.18 +/- 3.85 years in boys (9.96 +/- 4.03 years in all children). Mean age at the onset of the disease was 6.81 +/- 4.11 years in girls and 7.03 +/- 4.28 years in boys (6.89 +/- 4.14 years in all patients). In 14 (23%) cases, a positive family history was detected. The most frequent probable triggering factors were upper respiratory tract infections (14.8%) and positive throat culture for A group ss-hemolytic streptococcus (21.3%). Frequency of emotional stress and psychiatric morbidity were 54% and 9.8%, respectively. The most frequent localizations at onset were trunk (44.3%), extremities (54.0%), and scalp (36.0%). Three children (4.9%) had a history of dissemination from psoriatic diaper rash. In total, 51 (83.6%) patients presented with psoriasis vulgaris, eight (13.1%) with generalized pustular psoriasis, and the remaining two (3.3%) with erythrodermic psoriasis. CONCLUSION: The incidence of psoriasis among dermatological patients in childhood and adolescence was 3.8%. The disease tends to appear earlier in girls than boys. The authors suggested that stress and upper respiratory infections are the most important triggering factors in childhood and adolescence psoriasis.  相似文献   
2.
3.
Low-trauma fractures of elderly people are a major public health burden worldwide, and as the number and mean age of older adults in the population continue to increase, the number of fractures is also likely to increase. Epidemiologically, however, an additional concern is that, for unknown reasons, the age-standardized incidence (average individual risk) of fracture has also risen in many populations during the recent decades. Possible reasons for this rise include a birth cohort effect, deterioration in the average bone strength by time, and increased average risk of (serious) falls. Literature provides evidence that the rise is not due to a birth cohort effect, whereas no study shows whether bone fragility has increased during this relatively short period of time. This osteoporosis hypothesis could, however, be tested if researchers would now repeat the population measurements of bone mass and density that were made in the late 1980s and the 1990s. If such studies proved that women's and men's age-standardized mean values of bone mass and density have declined over time, the osteoporosis hypothesis would receive scientific support. The third explanation is based on the hypothesis that the number and/or severity of falls has risen in elderly populations during the recent decades. Although no study has directly tested this hypothesis, a great deal of indirect epidemiologic evidence supports this contention. For example, the age-standardized incidence of fall-induced severe head injuries, bruises and contusions, and joint distortions and dislocations has increased among elderly people similarly to the low-trauma fractures. The fall hypothesis could also be tested in the coming years because the 1990s saw many research teams reporting age- and sex-specific incidences of falling for elderly populations, and the same could be done now to provide data comparing the current incidence rates of falls with the earlier ones.  相似文献   
4.
5.
6.
7.
8.
9.
10.
PURPOSETo study the potential combined application of gadolinium and magnetization transfer in the MR imaging of intracranial tumors.METHODSTwenty-two patients were imaged at low field strength (0.1 T). Corresponding gradient-echo partial saturation images without and with magnetization transfer pulse were produced. Images with intermediate repetition times were obtained in 18 cases; five different sequences were produced in 4 cases. Gadopentetate dimeglumine was used at a dose of 0.1 mmol/kg.RESULTSMagnetization transfer effect increased the contrast between enhancing lesion and normal brain and the contrast between edema and normal brain; the contrast between enhancing lesion and edema was not significantly changed. On intermediate-repetition-time magnetization transfer images the contrast between enhancing tumor and normal brain and the contrast between edema and normal brain were superior to short-repetition-time magnetization transfer images, but the differentiation between enhancing tumor and edema was poorer.CONCLUSIONMagnetization transfer can be used to improve contrast in Gd-enhanced MR imaging. Combining magnetization transfer with an intermediate-repetition-time image provides the possibility for displaying both enhancing and nonenhancing lesions on a single MR image.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号