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   4709篇
  免费   202篇
  国内免费   20篇
耳鼻咽喉   172篇
儿科学   218篇
妇产科学   208篇
基础医学   670篇
口腔科学   44篇
临床医学   286篇
内科学   1115篇
皮肤病学   63篇
神经病学   435篇
特种医学   95篇
外科学   286篇
综合类   34篇
一般理论   1篇
预防医学   395篇
眼科学   86篇
药学   564篇
中国医学   12篇
肿瘤学   247篇
  2024年   6篇
  2023年   39篇
  2022年   245篇
  2021年   364篇
  2020年   128篇
  2019年   142篇
  2018年   178篇
  2017年   140篇
  2016年   143篇
  2015年   181篇
  2014年   206篇
  2013年   257篇
  2012年   402篇
  2011年   436篇
  2010年   195篇
  2009年   131篇
  2008年   259篇
  2007年   293篇
  2006年   265篇
  2005年   261篇
  2004年   249篇
  2003年   211篇
  2002年   136篇
  2001年   4篇
  2000年   4篇
  1999年   6篇
  1998年   7篇
  1997年   8篇
  1996年   8篇
  1995年   7篇
  1994年   3篇
  1993年   1篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1985年   2篇
  1984年   2篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1978年   2篇
  1976年   1篇
排序方式: 共有4931条查询结果,搜索用时 15 毫秒
71.
72.

Introduction

In normal conditions follicle-stimulating hormone receptors (FSHR) are expressed in the ovary and the testis. They can also be expressed in gonadal tumors. However, recently we have found FSHR immunostaining in pituitary adenomas, adrenal tumors and neuroendocrine tumors (carcinoids). The aim of this study was to determine whether the same occurs in thyroid tumors.

Material and methods

Thirty-six samples of surgically excised thyroids were examined. Follicle-stimulating hormone receptors immunostaining was performed on paraffin sections using the rabbit anti-human FSHR polyclonal antibody raised against a 1-190 amino acid sequence from the human FSHR (sc-13935, Santa Cruz).

Results

Normal thyroid follicles do not show immunopositivity for FSHR. The same concerns the majority of benign lesions, diagnosed as hyperplasia nodularis or thyroid adenomas. However, positive FSHR immunostaining in some follicles was observed. In all but one thyroid cancer (15 papillary, 10 follicular cancers and one case of anaplastic thyroid cancer) 10–100% of tumor cells exhibit positive FSHR immunostaining. In about 40% of samples FSHR immunoreactivity can be observed also in the endothelia of intrathyroidal blood vessels. This immunopositivity was more frequent in the samples of thyroid cancers (13/27) than in benign lesions (2/9).

Conclusions

Ectopic positive FSHR immunostaining is also present in thyroid cancers, and, to a lesser degree, in benign lesions but not in the normal thyroid epithelium.  相似文献   
73.
Lung ultrasound (LUS) has been increasingly used in diagnosing and monitoring of various pulmonary diseases in children. The aim of the current study was to evaluate its usefulness in children with persistent tachypnea of infancy (PTI). This was a controlled, prospective, cross‐sectional study that included children with PTI and healthy subjects. In patients with PTI, LUS was performed at baseline and then after 6 and 12 months of follow‐up. Baseline results of LUS were compared to (a) baseline high‐resolution computed tomography (HRCT) images, (b) LUS examinations in control group, and (c) follow‐up LUS examinations. Twenty children with PTI were enrolled. B‐lines were found in all children with PTI and in 11 (55%) control subjects (P < .001). The total number of B‐lines, the maximal number of B lines in any intercostal space, the distance between B‐lines, and pleural thickness were significantly increased in children with PTI compared to controls. An irregularity of the pleural line was found in all patients with PTI and in none of the healthy children. There were no significant changes in LUS findings in patients with PTI during the study period. The comparison of HRCT indices and LUS findings revealed significant correlations between the mean lung attenuation, skewness, kurtosis and fraction of interstitial pulmonary involvement, and the number of B‐lines as well as the pleural line thickness. LUS seems to be a promising diagnostic tool in children with PTI. Its inclusion in the diagnostic work‐up may enable to reduce the number of costly, hazardous, and ionizing radiation‐based imaging procedures.  相似文献   
74.
75.
76.
77.
78.
79.
AIM: To determine the prevalence and characteristics of additional primary malignancies in gastric cancer (GC) patients.METHODS: GC patients (862 total; 570 men, 292 women; mean age 59.8 ± 12.8 years) diagnosed at the Department of Gastroenterology at Pomeranian Medical University over a period of 23 years were included in this retrospective analysis of a prospectively maintained database. Mean follow-up time was 31.3 ± 38.6 mo (range 1-241 mo). The following clinicopathological features of patients with synchronous tumors were compared to those with metachronous tumors: age, sex, symptom duration, family history of cancer, tumor site, stage (early vs advanced), histology, and blood group. GC patients with and without a second tumor were compared in terms of the same clinicopathological features.RESULTS: Of 862 GC patients, 58 (6.7%) developed a total of 62 multiple primary tumors, of which 39 (63%) were metachronous and 23 (37%) synchronous. Four (6.9%) of the 58 multiple GC patients developed two or more neoplasms. The predominant tumor type of the secondary neoplasms was colorectal (n = 17), followed by lung (n = 9), breast (n = 8), and prostate (n = 7). Age was the only clinicopathological feature that differed between GC patients with synchronous vs metachronous malignancies; GC patients with synchronous neoplasms were older than those with metachronous neoplasms (68.0 ± 10.3 years vs 59.9 ± 11.1 years, respectively, P = 0.008). Comparisons between patients with and without a second primary cancer revealed that the only statistically significant differences were in age and blood group. The mean age of the patients with multiple GC was higher than that of those without a second primary tumor (63.4 ± 11.4 years vs 59.5 ± 13.0 years, respectively, P = 0.026). GC patients with a second primary tumor were more commonly blood group O than those without (56.2% vs 31.6%, respectively, P = 0.002).CONCLUSION: GC patients may develop other primary cancers; appropriate preoperative and postoperative diagnostic modalities are thus required, particularly if patients are older and blood group O.  相似文献   
80.

Aims/hypothesis

Fetal programming plays an important role in the pathogenesis of type 2 diabetes. The aim of the present study was to investigate whether maternal metabolic changes during OGTT influence fetal brain activity.

Methods

Thirteen healthy pregnant women underwent an OGTT (75 g). Insulin sensitivity was determined by glucose and insulin measurements at 0, 60 and 120 min. At each time point, fetal auditory evoked fields were recorded with a fetal magnetoencephalographic device and response latencies were determined.

Results

Maternal insulin increased from a fasting level of 67?±?25 pmol/l (mean ± SD) to 918?±?492 pmol/l 60 min after glucose ingestion and glucose levels increased from 4.4?±?0.3 to 7.4?±?1.1 mmol/l. Over the same time period, fetal response latencies decreased from 297?±?99 to 235?±?84 ms (p?=?0.01) and then remained stable until 120 min (235?±?84 vs 251?±?91 ms, p?=?0.39). There was a negative correlation between maternal insulin sensitivity and fetal response latencies 60 min after glucose ingestion (r?=?0.68, p?=?0.02). After a median split of the group based on maternal insulin sensitivity, fetuses of insulin-resistant mothers showed a slower response to auditory stimuli (283?±?79 ms) than those of insulin-sensitive mothers (178?±?46 ms, p?=?0.03).

Conclusions/interpretation

Lower maternal insulin sensitivity is associated with slower fetal brain responses. These findings provide the first evidence of a direct effect of maternal metabolism on fetal brain activity and suggest that central insulin resistance may be programmed during fetal development.  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