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   45297篇
  免费   3245篇
  国内免费   150篇
耳鼻咽喉   343篇
儿科学   1337篇
妇产科学   983篇
基础医学   5982篇
口腔科学   1228篇
临床医学   4679篇
内科学   9146篇
皮肤病学   642篇
神经病学   4698篇
特种医学   1690篇
外国民族医学   6篇
外科学   6499篇
综合类   656篇
一般理论   61篇
预防医学   3323篇
眼科学   1421篇
药学   3170篇
中国医学   60篇
肿瘤学   2768篇
  2023年   133篇
  2022年   247篇
  2021年   656篇
  2020年   402篇
  2019年   638篇
  2018年   810篇
  2017年   605篇
  2016年   661篇
  2015年   743篇
  2014年   1097篇
  2013年   1985篇
  2012年   2736篇
  2011年   3034篇
  2010年   1634篇
  2009年   1537篇
  2008年   2849篇
  2007年   3191篇
  2006年   3107篇
  2005年   3114篇
  2004年   2895篇
  2003年   2878篇
  2002年   2763篇
  2001年   434篇
  2000年   362篇
  1999年   446篇
  1998年   629篇
  1997年   544篇
  1996年   440篇
  1995年   458篇
  1994年   432篇
  1993年   423篇
  1992年   368篇
  1991年   320篇
  1990年   270篇
  1989年   261篇
  1988年   274篇
  1987年   240篇
  1986年   291篇
  1985年   308篇
  1984年   444篇
  1983年   404篇
  1982年   462篇
  1981年   420篇
  1980年   437篇
  1979年   218篇
  1978年   251篇
  1977年   263篇
  1976年   197篇
  1975年   172篇
  1974年   178篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
11.
12.
13.
A high resolution depth attenuation product (Kdhires) was developed using MODIS 500 m and 250 m spectral bands. The Kdhires was compared with Wang’s operational Kd for the Chesapeake Bay. Minimal differences were observed between the two methods, with greatest deviation occurring in areas of high turbidity in the tributaries. After tuning the new Kdhires, the mean absolute error and bias between the two algorithms was 0.22 m?1 and 0.026 m?1, indicating good agreement. Higher spatial resolution provides for improved retrievals along the coast and into the narrow sections of the tributaries, coinciding with areas of concern to estuarine health and coastal management applications.  相似文献   
14.
Background. A persistent patent ductus arteriosus (PDA) may delay closure of a coexisting atrial septal defect (ASD) due to volume loading and enlargement of the left atrium. The purpose of this study was to investigate the natural history of ASD size in patients with a PDA following transcatheter PDA occlusion. Methods. All patients with an ASD and a PDA who underwent transcatheter PDA occlusion at Texas Children’s Hospital were identified. Patients with ASD diameter <3 mm, or additional cardiac defects were excluded. Eight patients (7 females) with small‐ to moderate‐sized ASDs and a PDA were identified. Patient demographics, echocardiographic data, and cardiac catheterization data were recorded. Data were analyzed by 1‐tailed t‐test. Results. Following PDA occlusion, ASD diameter decreased in 6 of 8 patients by a mean of 3.8 mm (±2.3 mm), including 2 that closed. The median duration of follow‐up was 689 days. One ASD remained unchanged and 1 increased in size. The mean maximum ASD diameter decreased from 6.4 mm (±2.2 mm) to 3.9 mm (±3.4 mm) (P = .03). Two patients underwent subsequent transcatheter ASD occlusion. Conclusion. Following transcatheter PDA occlusion, small‐ to moderate‐sized ASDs have significant probability to decrease in size, and possibly close. In infants and children, we recommend transcatheter PDA occlusion, and serial follow‐up of the size of the ASD. This will allow many small‐ to moderate‐sized ASDs to either close, or become smaller, obviating the need for future intervention.  相似文献   
15.
Gorlin syndrome (naevoid basal cell carcinoma syndrome) is a genetically linked disorder characterized by the development of multiple basal cell carcinomas (BCCs) throughout life. Cumulative surgery, cryotherapy and other conventional interventions can result in significant disfigurement by middle age. Radiotherapy is contra-indicated because the mutated gene underlying the syndrome, ‘PTCH’, increases sensitivity to ionising radiation, so there is significant likelihood of inducing further tumours in and around the irradiated area. Photodynamic therapy offers a non-invasive treatment option for patients with this condition, with the added advantage of causing minimal scarring.  相似文献   
16.
17.
We describe a case of a palatal tic resembling palatal tremor (PT) in a young female patient with a previously unrecognized mild Tourette syndrome. At the time of her visit, the patient complained about ear clicks that were audible to others. We discuss the differential diagnoses of hyperkinetic palatal movements emphasizing the ongoing discussion about essential PT representing a more heterogeneous disorder than previously thought.  相似文献   
18.
We thank Geluk and Zijlstra for their kind words as well astheir considerations and proposals. The latter hits right intothe heart of the issue: should one stick to the ‘anatomic’paradigm urging us to detect and treat coronary stenoses andcalcifications rather than follow  相似文献   
19.
20.
BACKGROUND: Changes in the hypothalamic-pituitary-adrenal (HPA) axis, as evidenced by patterns of cortisol secretion, have been of interest in understanding depression and anxiety disorders across the life span. Previous studies of pediatric depression have pointed to the period around sleep onset as a key time point for observing alterations in cortisol secretion associated with affective disorders. Evidence also indicates that pubertal development may influence the expression of HPA dysregulation. We hypothesized that adolescents with depression and youth with anxiety disorders exhibit elevated peri-sleep-onset cortisol. METHODS: Plasma cortisol was sampled every 20 min around sleep onset from children and adolescents with major depressive disorder (n = 116), anxiety disorders (n = 32), or no history of psychiatric disorder (control; n = 76). Sleep onset was determined by polysomnography. Classification of participants as children or adolescents was based on Tanner staging of pubertal maturation. RESULTS: Children with anxiety disorders had higher peri-sleep-onset cortisol than children with depression or control children. Adolescents with depression had marginally higher peri-sleep-onset cortisol than control adolescents and significantly higher peri-sleep-onset cortisol than children with depression. CONCLUSIONS: Depression and anxiety are associated with altered cortisol secretion around sleep onset, and these changes appear to be influenced by pubertal maturation.  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