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   156篇
  免费   10篇
耳鼻咽喉   3篇
儿科学   5篇
妇产科学   2篇
基础医学   28篇
口腔科学   5篇
临床医学   11篇
内科学   29篇
皮肤病学   2篇
神经病学   11篇
特种医学   2篇
外科学   24篇
预防医学   10篇
眼科学   6篇
药学   11篇
肿瘤学   17篇
  2023年   1篇
  2022年   1篇
  2021年   5篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   3篇
  2016年   2篇
  2015年   5篇
  2014年   2篇
  2013年   5篇
  2012年   4篇
  2011年   10篇
  2010年   4篇
  2009年   9篇
  2008年   5篇
  2007年   3篇
  2006年   5篇
  2005年   1篇
  2004年   3篇
  2003年   6篇
  2002年   6篇
  2001年   13篇
  2000年   12篇
  1999年   11篇
  1998年   5篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1991年   2篇
  1987年   1篇
  1986年   2篇
  1981年   2篇
  1980年   1篇
  1976年   1篇
  1974年   2篇
  1973年   3篇
  1972年   4篇
  1971年   5篇
  1970年   1篇
  1967年   1篇
  1966年   2篇
  1965年   1篇
  1962年   3篇
  1961年   1篇
  1926年   1篇
  1912年   1篇
排序方式: 共有166条查询结果,搜索用时 31 毫秒
1.
BACKGROUND: In most examined populations the RET germline polymorphism S836S is found in about 3.6% of the normal population but in about 9% of patients suffering from sporadic C-cell hyperplasia or medullary thyroid carcinoma. The polymorphism S836S is thought to be involved in the development of sporadic medullary thyroid carcinoma. CASE PRESENTATION: We report a 48-year-old woman suffering from primary hyperparathyroidism (parathormone 121-166 pg/ml, normal <72), bilateral diffuse and nodular C-cell hyperplasia (calcitonin after pentagastrin administration 156 pg/ml, normal <4.6), and papillary thyroid carcinoma. Two commercial analyses of RET did not reveal any germline mutation within the known hot spots. However, sequencing revealed the presence of the RET polymorphism S836S. Following total thyroidectomy and removal of two hyperplastic parathyroid glands parathormone decreased to 51 pg/ml and calcitonin was no longer detected. CONCLUSIONS: The pathogenetic importance of the RET polymorphism S836S is still obscure. However, according to the published overrepresentation of the RET polymorphism S836S in patients suffering from apparent sporadic medullary thyroid carcinoma, it is conceivable that it also plays a role in multiglandular endocrine disease.  相似文献   
2.
We investigated the influence of the adenosine antagonist theophylline on the degree of hippocampal cell damage in the Mongolian gerbil following brief periods of forebrain ischemia. Male gerbils were randomly divided into nine groups. Ten minutes before surgery, four groups, which were later subjected to 1, 2, 3, or 5 min of bilateral carotid occlusion under halothane anesthesia, received theophylline (30 mg/kg, p.o.). Four groups served as nontreated ischemic controls; the ninth group was used to measure theophylline serum concentration. Neurological symptoms were classified by using a behavioral score. Fourteen days after ischemia, the brains were removed, and the hippocampus was histologically examined "blind" for the degree of cell damage in the CA1 sector, which was expressed as a semiquantitative histopathological score. There were no behavioral or histological abnormalities in either the control or theophylline group with 1 min of ischemia. With increasing duration of ischemia, the neurological symptoms worsened and the number of necrotic pyramidal cells increased significantly. The pretreatment with theophylline only moderately aggravated the neurological symptoms, whereas it enhanced the ischemic cell damage significantly. The results are discussed with respect to recent findings that theophylline may block putatively protective effects of endogenous adenosine, whose concentration in the brain is known to rise significantly during ischemia.  相似文献   
3.
Prevention Science - There is evidence that universal school-based mindfulness training (SBMT) can have positive effects for young people. However, it is unknown who benefits most from such...  相似文献   
4.
5.
Although suicidal ideation is one of the most consistent symptoms across recurrent episodes of depression, the mechanisms underpinning its maintenance are poorly understood. In order to develop effective treatments for suicidally depressed patients, understanding what maintains suicidal distress is critical. We hypothesised that Thought–Action Fusion (TAF), i.e., to assume that having a thought has real world consequences, originally described in Obsessive–Compulsive Disorder, might be a bias in recurrently suicidally depressed people. To assess this, we revised the original TAF scale, and assessed TAF in three samples: healthy controls, recurrently depressed individuals with no history of suicidality (D-NS) and individuals with a history of recurrent suicidal depression (D-S). Exploratory and confirmatory factor analyses indicated a three-factor solution of TAF: (1) TAF for uncontrollable events, (2) self-suicidal TAF for suicidal acts related to oneself, and (3) TAF for positive controllable events. Compared to healthy controls, the D-NS group reported significantly higher total TAF, TAF uncontrollable, and TAF self-suicidal subscales, whilst positive controllable TAF was lower compared to healthy controls. Both D-S and D-NS samples reported higher TAF for suicidal thought compared to healthy controls, i.e., believing that having suicidal thoughts means they will act on them, however in the context of low mood this became more pronounced for the D-S group. These findings suggest that targeting TAF both in suicidal and non-suicidal depression has merit.  相似文献   
6.
Primary pulmonary rhabdomyosarcoma is a rare entity and the histological differential diagnosis can be difficult. We report on a 43-year old female patient, smoker (25 pack-years), in whom a large solitary brain metastasis was diagnosed and enucleated. Histological examination revealed a typical small cell carcinoma and histological examination of biopsies obtained from a tumor in the left upper lobe of the lung was compatible with a small cell carcinoma. Despite chemotherapy there was a progressive tumor growth. Bronchial biopsies again showed a small cell tumor, although immunohistochemistry proved it to be a pleomorphic rhabdomyosarcoma. Due to the progressive tumor growth with necrosis and superinfection and a lack of further metastases lobectomy of the left upper lobe was performed, complicated by postoperative pleural empyema, limiting the possibilities of adjuvant therapy. Early relapse occurred with pleural, pulmonary, chest wall and spinal metastases. Laminectomy and extirpation of the spinal metastases, local radiotherapy and chemotherapy with iphosphamide and doxorubicine led to partial remission and clinical improvement for few months only. The patient died from metastatic primary rhabdomyosarcoma of the lung. This rare tumor mimicked small cell lung cancer. Appraisal of the atypical clinical course and a close dialogue between pathologists and clinicians enabled the correct diagnosis.  相似文献   
7.
The fact that the transmission and processing of visual information in the brain takes time presents a problem for the accurate real-time localization of a moving object. One way this problem might be solved is extrapolation: using an object''s past trajectory to predict its location in the present moment. Here, we investigate how a simulated in silico layered neural network might implement such extrapolation mechanisms, and how the necessary neural circuits might develop. We allowed an unsupervised hierarchical network of velocity-tuned neurons to learn its connectivity through spike-timing-dependent plasticity (STDP). We show that the temporal contingencies between the different neural populations that are activated by an object as it moves causes the receptive fields of higher-level neurons to shift in the direction opposite to their preferred direction of motion. The result is that neural populations spontaneously start to represent moving objects as being further along their trajectory than where they were physically detected. Because of the inherent delays of neural transmission, this effectively compensates for (part of) those delays by bringing the represented position of a moving object closer to its instantaneous position in the world. Finally, we show that this model accurately predicts the pattern of perceptual mislocalization that arises when human observers are required to localize a moving object relative to a flashed static object (the flash-lag effect; FLE).SIGNIFICANCE STATEMENT Our ability to track and respond to rapidly changing visual stimuli, such as a fast-moving tennis ball, indicates that the brain is capable of extrapolating the trajectory of a moving object to predict its current position, despite the delays that result from neural transmission. Here, we show how the neural circuits underlying this ability can be learned through spike-timing-dependent synaptic plasticity and that these circuits emerge spontaneously and without supervision. This demonstrates how the neural transmission delays can, in part, be compensated to implement the extrapolation mechanisms required to predict where a moving object is at the present moment.  相似文献   
8.
9.
Genetic testing for RET germline mutations affords rapid identification of germline carriers, offering the prospect of cure before C-cell hyperplasia (CCH) has progressed to medullary thyroid carcinoma (MTC). Although nonindex RET mutation carriers have a better prognosis than do the index patients, it remains to be ascertained whether age represents a risk factor for MTC when screening patients. The current institutional study (October 1994 through June 1999) was set up to compare asymptomatic nonindex patients who were grouped by age: < 20 years and ≥ 20 years. Inclusion criteria were confirmed RET mutations in the germline, with no MTC being more advanced than pT1pN1M0. Adult patients (≥ 20 years) had MTC significantly more often (84% vs. 43%), significantly larger tumors (5 mm vs. 3 mm), and significantly higher basal calcitonin levels preoperatively (78.0 vs. 9.7 pg/ml) than their pediatric/adolescent counterparts (< 20 years). There was a close correlation between pT1 MTC and an elevated basal serum calcitonin level (r= 0.67; Spearman's rho). All three patients with lymph node metastases from MTC had elevated basal calcitonin levels. The two groups did not differ in terms of multifocality of MTC (pT1b), lymph node involvement (pN1) or bilateral lymph node metastasis (pN1b), or preoperative stimulated and postoperative basal and stimulated serum calcitonin. Prophylactic thyroidectomy should not be postponed beyond the age of 20, and it should be performed before basal serum calcitonin has turned positive. Pathologic conversion of stimulated serum calcitonin obviously marks the time in carriers of RET germline mutations when surgery should be scheduled at the latest to be prophylactic.  相似文献   
10.
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