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   1422篇
  免费   126篇
  国内免费   30篇
耳鼻咽喉   1篇
儿科学   97篇
妇产科学   18篇
基础医学   222篇
口腔科学   51篇
临床医学   145篇
内科学   280篇
皮肤病学   17篇
神经病学   33篇
特种医学   270篇
外科学   132篇
综合类   22篇
预防医学   93篇
眼科学   11篇
药学   99篇
中国医学   13篇
肿瘤学   74篇
  2023年   4篇
  2022年   11篇
  2021年   25篇
  2020年   11篇
  2019年   18篇
  2018年   29篇
  2017年   25篇
  2016年   27篇
  2015年   30篇
  2014年   36篇
  2013年   32篇
  2012年   37篇
  2011年   38篇
  2010年   49篇
  2009年   39篇
  2008年   39篇
  2007年   57篇
  2006年   46篇
  2005年   39篇
  2004年   32篇
  2003年   45篇
  2002年   32篇
  2001年   36篇
  2000年   27篇
  1999年   27篇
  1998年   65篇
  1997年   76篇
  1996年   80篇
  1995年   49篇
  1994年   40篇
  1993年   44篇
  1992年   19篇
  1991年   23篇
  1990年   27篇
  1989年   51篇
  1988年   50篇
  1987年   41篇
  1986年   35篇
  1985年   44篇
  1984年   16篇
  1983年   13篇
  1982年   16篇
  1981年   13篇
  1980年   14篇
  1979年   10篇
  1978年   7篇
  1977年   16篇
  1976年   15篇
  1975年   7篇
  1973年   3篇
排序方式: 共有1578条查询结果,搜索用时 125 毫秒
991.
The aim of this study is to demonstrate the spectrum of mammographic appearances of mammary duct ectasia that mimic carcinoma in a breast cancer screening programme. Between February 1989 and March 1993, 40 003 women underwent screening mammography as part of the Western Australia Women's Cancer Prevention Unit screening programme. Fine needle aspiration or excisional biopsy was performed on 1437 women, and 12 cases of cytologically or histologically confirmed mammary duct ectasia were detected. A total of 14 mammographic abnormalities from 12 asymptomatic female patients were biopsied, and confirmed to represent mammary duct ectasia. The mammographic spectrum included eight areas of microcalcification (two of which were extensive), three spiculated masses and three lobulated, partially smooth masses. Five of these women showed no other mammographic stigmata of mammary duct ectasia in either breast. Additional features of mammary duct ectasia, including nipple retraction, retro-areolar duct dilatation or macrocalcification were identified in seven women. Mammographic features of mammary duct ectasia are frequently detected in asymptomatic women undergoing screening mammography and cause no diagnostic dilemma. Occasionally mammary duct ectasia will have a mammographic appearance that is indistinguishable from carcinoma, necessitating breast biospy. In this study 40% of those women with mammary duct ectasia that were submitted for biopsy had no other feature of mammary duct ectasia that could have suggested the pre-operative diagnosis.  相似文献   
992.
993.
1. Central serotonergic pathways are hypothesized to be involved in the stimulation of hypothalamic adrenocorticotropic hormone (ACTH) secretagogue release by both circadian- and stress-induced mechanisms. We aimed to investigate this hypothesis by measuring the effect of the highly specific serotonin re-uptake inhibitor fluoxetine (FX) on ACTH and Cortisol release in the morning and in the afternoon in humans, both by itself and in combination with the opioid antagonist naloxone (Nal). Naloxone causes ACTH release in humans by removing an endogenous inhibitory opioid tone on central noradrenergic pathways stimulatory to hypothalamic corticotropin-releasing hormone (CRH) secretion. Serotonergic agents may act directly or indirectly through these central noradrenergic pathways and, if so, would be expected to be additive to or synergistic with Nal in causing ACTH and Cortisol release. 2. Oral FX (40 mg) was given at approximately 07.00 or 11.00 h, either alone or with intravenous Nal 3 h later, to normal human volunteers. Plasma ACTH and Cortisol levels were measured for 5 h after FX dosing. 3. Fluoxetine produced a small but non-significant increase in Nal-stiimilated ACTH and Cortisol release in both morning and afternoon studies. Naloxone alone did not cause different ACTH and Cortisol responses in the morning and afternoon. 4. These results suggest that serotonergic pathways are not major regulators of the hypothalamic-pituitary-adrenal axis in humans or that FX has counteracting acute inhibitory effects on the axis, such as inhibition of hypothalamic arginine vasopressin secretion, which has been demonstrated in chronic animal studies.  相似文献   
994.
Loss of genetic material from chromosome arm 8p occurs commonly in breast carcinomas, suggesting that this region is the site of one or more tumor-suppressor genes (TSGs). Comparative genomic hybridization analysis showed that 8p loss is more common in breast cancers from pre-menopausal compared with post-menopausal patients, as well as in high-grade breast cancers, regardless of the menopausal status. Subsequent high-resolution gene expression profiling of genes mapped to chromosome arm 8p, on an extended cohort of clinical tumor samples, indicated a similar dichotomy of breast cancer clinicopathologic types. Some of these genes showed differential downregulation in early-onset and later-onset, high-grade cancers compared with lower-grade, later-onset cancers. Three such genes were analysed further by in situ technologies, performed on tissue microarrays representing breast tumor and normal tissue samples. PCM1, which encodes a centrosomal protein, and DUSP4/MKP-2, which encodes a MAP kinase phosphatase, both showed frequent gene and protein loss in carcinomas. In contrast, there was an excess of cases showing loss of expression in the absence of reduced gene copy number of SFRP1, which encodes a dominant-negative receptor for Wnt-family ligands. These candidate TSGs may constitute some of the molecular drivers of chromosome arm 8p loss in breast carcinogenesis.  相似文献   
995.
996.
Both congestive heart failure and chronic obstructive pulmonary disease are more common among Māori than non-Māori people, and the cultural acceptability of home-based remote monitoring technology has not been tested. We conducted a 12-month pilot trial of home telemonitoring. Patients were randomly assigned to the control and intervention groups. Patients in the control group showed no clear differences in quality of life at the end of the trial. The telehealth group showed a consistent trend towards improved quality of life on several instruments, including the SF-36, the St George Respiratory Questionnaire and the K10 questionnaire; the improvement in the latter was significant. Hospitalizations were reduced in both the control (-19%) and telehealth group (-25%). Patient interviews indicated that the technology was acceptable to most patients and their families, including the Māori. The results from the pilot trial suggest that wider implementation with a cost benefit evaluation could be worthwhile.  相似文献   
997.

Introduction

The gold standard for assessing neck lumps is a one-stop clinic with an on-site cytopathologist who can provide an immediate fine needle aspiration (FNA) report. However, this has considerable resource implications and is not available in all units. In our department, surgeons perform FNAs guided by palpation. The FNA is evaluated for specimen adequacy by an on-site cytotechnician. This study evaluated the impact of the cytotechnician on the adequacy of neck lump FNA.

Methods

FNA performed between June 2010 and February 2012 was examined. The FNA performed at a neck lump clinic with an assessment of adequacy by an on-site cytotechnician were considered the test group. All other neck lump FNAs from other sources without an assessment of adequacy by an on-site cytotechnician were considered the control group.

Results

Of the FNAs, 134 met the inclusion criteria for this study. Of these, 87 FNAs (65%) were analysed for adequacy by the on-site cytotechnician and the remaining 47 (35%) were not. The results demonstrated an FNA inadequacy with and without on-site cytotechnician assessment of 29.9% and 40.4% respectively. This is equivalent to an absolute risk reduction of an inadequate FNA of 10.5%, which equates to a number needed to treat of 9.5, ie the cytotechnician needs to assess 9.5 (ie the cytotechnician […] specimen).

Conclusions

In neck lump clinics where on-site cytopathology is not available, an on-site cytotechnician is a compromise measure that does reduce the number of inadequate FNAs.  相似文献   
998.
999.
1000.
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