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   474篇
  免费   17篇
  国内免费   22篇
儿科学   27篇
基础医学   43篇
口腔科学   9篇
临床医学   52篇
内科学   73篇
皮肤病学   3篇
神经病学   1篇
特种医学   184篇
外科学   24篇
综合类   2篇
预防医学   14篇
眼科学   7篇
药学   44篇
肿瘤学   30篇
  2023年   1篇
  2021年   4篇
  2020年   1篇
  2019年   1篇
  2018年   4篇
  2017年   1篇
  2015年   2篇
  2014年   2篇
  2013年   12篇
  2012年   2篇
  2011年   4篇
  2010年   11篇
  2009年   9篇
  2008年   8篇
  2007年   22篇
  2006年   8篇
  2005年   13篇
  2004年   7篇
  2003年   6篇
  2002年   3篇
  2001年   9篇
  2000年   5篇
  1999年   3篇
  1998年   32篇
  1997年   44篇
  1996年   25篇
  1995年   27篇
  1994年   19篇
  1993年   12篇
  1992年   3篇
  1991年   8篇
  1990年   10篇
  1989年   19篇
  1988年   25篇
  1987年   16篇
  1986年   18篇
  1985年   22篇
  1984年   10篇
  1983年   8篇
  1982年   16篇
  1981年   7篇
  1980年   15篇
  1979年   6篇
  1978年   7篇
  1977年   8篇
  1976年   14篇
  1975年   4篇
排序方式: 共有513条查询结果,搜索用时 389 毫秒
81.
CT模拟结肠镜在结肠病灶诊断中的应用   总被引:2,自引:0,他引:2  
结肠癌是常见的消化道肿瘤,上海等地区的发病率有明显增高的趋势。在发达国家,结肠癌占肿瘤死亡率第二位,且与大肠腺瘤关系密切。如能早期发现有恶变先兆的息肉并切除之,可以预防结肠癌发生。目前,对结肠癌发病高危人群并未作大规模普查,部分由于患者缺乏早期主诉,或是由于现有普查手段不够有效。大便隐血试验只能发现30%~40%结肠肿瘤,乙状结肠镜不能进入近端结肠,并有10%~15%乙状结肠肿瘤漏诊。钡剂灌肠和结肠镜能检查全结肠,但有10%~15%患者行结肠镜检查失败,并且结肠镜可能使10%~20%病灶遗漏,尚…  相似文献   
82.
83.
输血是挽救创伤患者生命而普遍使用的治疗方法,但其又存在着明显和潜在的危险性。当今,经血液传播传染病和输血反应很少发生,但仍然存在。尽管在临床治疗中试图控制创伤患者休克的发展及损伤的严重度,但其输血后细菌感染、多脏器功能衰竭、死亡的发生率仍较高。  相似文献   
84.
ObjectiveTo ascertain the socio-cultural factors influencing the rate of utilization of insecticide treated bed nets (ITNs) in a malaria endemic city of Makurdi, north central Nigeria.MethodsThe study was cross-sectional in nature using systematic sampling method to identify households. Both quantitative and qualitative data was generated from adult women using structured and semi structured questionnaires, and focused group discussions (FGDs) to obtain information on rate and patterns of utilization of ITNs. Information such as age, educational level, marital status, awareness or otherwise of the existence of malaria, and factors influencing rate of ownership and utilization of ITNs were obtained. FGDs were used to obtain qualitative information on rate of utilization of ITNs not captured in the questionnaires. Data obtained was analysed using Epi Info 6 statistical software.ResultsAmong the respondents interviewed, 97.0% (2 013/2 075) were aware of existence of malaria and 87.0% of these (1 751/2 013) would associate it with mosquitoes. The rate of ownership of any bed net, ITNs and untreated bed nets (UTNs) was 25.1%, 17.0% and 8.3%, respectively. Utilization of ITNs among children was 30.0% (112/373) and UTNs 12.9% (48/373). Positive contributors to ITNs utilization were literacy, enhanced economy, experience of marriage, and being gainfully employed (P<0.05); while negative contributors were ignorance, poverty and some cultural beliefs and values.ConclusionsA more synchronized advocacy should be carried out on the potential benefits of ITNs utilization and sustained. Also ITNs should be made available to the people of the community at minimal or no cost.  相似文献   
85.

Background

Clomiphene citrate (CC) is first line treatment in women with World Health Organization (WHO) type II anovulation and polycystic ovary syndrome (PCOS). Whereas 60% to 85% of these women will ovulate on CC, only about one half will have conceived after six cycles. If women do not conceive, treatment can be continued with gonadotropins or intra-uterine insemination (IUI). At present, it is unclear for how many cycles ovulation induction with CC should be repeated, and when to switch to ovulation induction with gonadotropins and/or IUI.

Methods/Design

We started a multicenter randomised controlled trial in the Netherlands comparing six cycles of CC plus intercourse or six cycles of gonadotrophins plus intercourse or six cycles of CC plus IUI or six cycles of gonadotrophins plus IUI.Women with WHO type II anovulation who ovulate but did not conceive after six ovulatory cycles of CC with a maximum of 150 mg daily for five days will be included.Our primary outcome is birth of a healthy child resulting from a pregnancy that was established in the first eight months after randomisation. Secondary outcomes are clinical pregnancy, miscarriage, multiple pregnancy and treatment costs. The analysis will be performed according to the intention to treat principle. Two comparisons will be made, one in which CC is compared to gonadotrophins and one in which the addition of IUI is compared to ovulation induction only. Assuming a live birth rate of 40% after CC, 55% after addition of IUI and 55% after ovulation induction with gonadotrophins, with an alpha of 5% and a power of 80%, we need to recruit 200 women per arm (800 women in total).An independent Data and Safety Monitoring Committee has criticized the data of the first 150 women and concluded that a sample size re-estimation should be performed after including 320 patients (i.e. 80 per arm).

Discussion

The trial will provide evidence on the most effective, safest and most cost effective treatment in women with WHO type II anovulation who do not conceive after six ovulatory cycles with CC with a maximum of 150 mg daily for five days. This evidence could imply the need for changing our guidelines, which may cause a shift in large practice variation to evidence based primary treatment for these women.

Trial registration number

Netherlands Trial register NTR1449
  相似文献   
86.
OBJECTIVES: The popularity of snuff especially among adolescents is rising. The association between long-term snuff use and oral cancer discovered in epidemiological studies has prompted a variety of preventive measures to be taken to reduce snuff use and prevent adoption of the habit. In this study, the effect of a recent (I March, 1995) snuff sales ban introduced in Finland was investigated. Further, the rates of smoking, snuff use, alcohol use and drug experimenting were investigated before the introduction of the ban to characterize the study population.
DESIGN AND SUBJECTS: Two questionnaire studies were carried out. The first was carried out 3 months prior to the ban in 1994 and the second 9 months after the ban in 1995 in a senior high school population in southwestern Finland. The participants were 793 students (aged 15–22 years) in the first survey and 545 students (aged 16–23) in the second. Associations between variables were analyzed using cross-tabulation and stepwise logistic regression. The effects of the ban were determined on the basis of direct questions in the second questionnaire relating to the snuff sales ban.
RESULTS: Snuff was used by 9% of the students participating in the first study. The results of the second questionnaire indicate that the implementation of the snuff sales ban reduced the rate of snuff use by 1% in the study population. The majority of the snuff users (76%) reported that they had maintained their snuff habit. Of those reporting that they were snuff users before implementation of the snuff sales ban, 12% had switched to smoking and 5% to drugs.
CONCLUSIONS: The results of the present study suggest that the snuff sales ban in this population with a high rate of snuff use had little effect on snuff use rates and may have some short-term negative consequences as some snuff users switch to other substitutes, such as smoking, with known adverse health effects.  相似文献   
87.

Introduction

Previous studies indicate that overexpression of the membrane-associated mucin MUC4 is potently anti-adhesive to cultured tumor cells, and suppresses cellular apoptotic response to a variety of insults. Such observations raise the possibility that MUC4 expression could contribute to tumor progression or metastasis, but the potential involvement of MUC4 in breast cancer has not been rigorously assessed. The present study aimed to investigate the expression of the membrane mucin MUC4 in normal breast tissue, primary breast tumors and lymph node metastases, and to evaluate the role of MUC4 in promoting the malignant properties of breast tumor cells.

Methods

MUC4 expression levels in patient-matched normal and tumor breast tissue was initially examined by immunoblotting lysates of fresh frozen tissue samples with a highly specific preparation of anti-MUC4 monoclonal antibody 1G8. Immunohistochemical analysis was then carried out using tissue microarrays encompassing patient-matched normal breast tissue and primary tumors, and patient-matched lymph node metastases and primary tumors. Finally, shRNA-mediated knockdown was employed to assess the contribution of MUC4 to the cellular growth and malignancy properties of JIMT-1 breast cancer cells.

Results

Immunoblotting and immunohistochemistry revealed that MUC4 levels are suppressed in the majority (58%, p < 0.001) of primary tumors relative to patient-matched normal tissue. On the other hand, lymph node metastatic lesions from 37% (p < 0.05) of patients expressed higher MUC4 protein levels than patient-matched primary tumors. MUC4-positive tumor emboli were often found in lymphovascular spaces of lymph node metastatic lesions. shRNA-mediated MUC4 knockdown compromised the migration, proliferation and anoikis resistance of JIMT-1 cells, strongly suggesting that MUC4 expression actively contributes to cellular properties associated with breast tumor metastasis.

Conclusions

Our observations suggest that after an initial loss of MUC4 levels during the transition of normal breast tissue to primary tumor, the re-establishment of elevated MUC4 levels confers an advantage to metastasizing breast tumor cells by promoting the acquisition of cellular properties associated with malignancy.  相似文献   
88.

OBJECTIVE

To assess, in the newborn, the efficacy of a standard taping treatment used in children for two selected congenital toe abnormalities (curly/varus/underlapping toes and overlapping toes), and compare the outcome with the available world literature.

METHODS

All children referred by their family physician between January 2004 and January 2006 were included. The newborns were reviewed by one author (WGS) within 10 days of birth, assessed for severity, and the toes were taped in a standard manner if the abnormalities met the study criteria. After one and two months, the same author reviewed the children, and retaped the toes. The children’s toes were photographed before the taping and then after three months when the tape was removed permanently. After six months, the children, with their pictures, were sent to a second author (JTS), and were scored for the grade of severity and improvement using standard criteria.

RESULTS

The world literature and standard textbooks indicate a 25% spontaneous improvement of these abnormalities. The recommendation is for surgical correction at a later date because intervention with taping has not shown success after the newborn period. No prior studies have been undertaken in the newborn. In the present study of 84 toes, the abnormality occurred in 2.8% of newborns, and 94% of the toes were improved or cured with no complications related to the technique.

CONCLUSION

A simple, office-friendly technique of taping underlapping and overlapping toes in the newborn proved successful in 94% of the toes.  相似文献   
89.
Aim : To determine what New Zealand ophthalmologists, general practitioners and optometrists consider important ophthalmic topic areas requiring emphasis in the medical undergraduate curriculum. Method : A total of 793 questionnaires related to the content and teaching of undergraduate ophthalmology were sent to ophthalmologists, general practitioners and optometrists. Results were analysed separately for the three respondent groups and as a whole. Results : Four hundred and fourteen questionnaires were returned (52% return rate). Overall responses of the three participant groups were similar and agreed favourably with the current curriculum. The ability to measure visual acuity (97%) and pupillary reflexes (93%), perform ophthalmoscopy (92%), and assess visual fields (68%) were regarded as ‘important or essential’ by the majority of respondents. Only 53% of respondents consider the ability to diagnose chronic open angle glaucoma as important. The respondents stressed the importance of the diagnosis of predominantly anterior segment disease contrasting with the traditional bias towards the teaching of ophthalmoscopy and posterior segment disease. The majority of respondents stressed the importance of graduating medical students being able to treat bacterial and allergic conjunctivitis, styes, blepharitis, corneal abrasion, and corneal and conjunctival foreign bodies, areas present but not normally emphasized in current curricula. Conclusion : The findings of this study provided additional data to facilitate curriculum design and illustrated the value of an integrated problem‐based learning approach in ophthalmology undergraduate teaching.  相似文献   
90.
目的提高医院临时处方溃结Ⅰ号保留灌肠剂的稳定性,并对其中的主要成分含量进行控制。方法制备时加入助悬剂,用沉降容积比和再分散性选择适宜的助悬剂及其最佳助悬浓度,并用紫外分光光度法对主要成分柳氮磺吡啶的含量进行测定。结果在制剂中加入卡波母作为助悬剂0.15%就可以达到良好的助悬效果,而且制备的制剂再分散性好。结论加入卡波母作为助悬剂制备的制剂稳定,再分散性好,便于使用和保存。  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