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   6288篇
  免费   565篇
  国内免费   73篇
耳鼻咽喉   72篇
儿科学   127篇
妇产科学   187篇
基础医学   790篇
口腔科学   86篇
临床医学   604篇
内科学   1276篇
皮肤病学   54篇
神经病学   490篇
特种医学   211篇
外科学   1341篇
综合类   185篇
一般理论   3篇
预防医学   388篇
眼科学   203篇
药学   382篇
中国医学   52篇
肿瘤学   475篇
  2024年   6篇
  2023年   78篇
  2022年   75篇
  2021年   168篇
  2020年   160篇
  2019年   209篇
  2018年   194篇
  2017年   166篇
  2016年   208篇
  2015年   219篇
  2014年   275篇
  2013年   344篇
  2012年   480篇
  2011年   506篇
  2010年   319篇
  2009年   272篇
  2008年   410篇
  2007年   389篇
  2006年   382篇
  2005年   362篇
  2004年   354篇
  2003年   286篇
  2002年   293篇
  2001年   114篇
  2000年   95篇
  1999年   78篇
  1998年   47篇
  1997年   46篇
  1996年   32篇
  1995年   23篇
  1994年   27篇
  1993年   23篇
  1992年   37篇
  1991年   41篇
  1990年   29篇
  1989年   26篇
  1988年   12篇
  1987年   17篇
  1986年   6篇
  1985年   12篇
  1984年   7篇
  1983年   12篇
  1980年   8篇
  1979年   16篇
  1978年   5篇
  1974年   10篇
  1973年   6篇
  1972年   6篇
  1971年   8篇
  1970年   7篇
排序方式: 共有6926条查询结果,搜索用时 15 毫秒
71.

Purpose

The purpose of this study was to determine whether alfentanil given by a pharmacokinetic-based target controlled infusion (TCI) system under patient control is a suitable analgesic technique for extracorporeal shock wave lithotripsy (ESWL).

Methods

The design was an open, unblinded, noncomparative, prospective study. Forty outpatients undergoing ESWL were given patient maintained alfentanil TCI. Pain, nausea and sedation were assessed every 300 shocks. Vital signs were recorded every three minutes, pulse oximetry and electrocardiography being monitored continuously. Blood alfentanil concentration was measured for comparison with the predicted value.

Results

Alfentanil consumption (median 1.34 mg, range 0.8–3.6) and measured levels following treatment (median 60 ng·ml?1, range 15.6–134.3) varied widely. The precision of the TCI system and the median prediction error (bias) were both 49%. The median of pain scores recorded during treatment was 4 (range 0–8). The median respiration rate was 15 bpm (range 10–23), three patients required oxygen (SaO2 < 92%) Cardiovascular measurements were stable and there was no excessive sedation. The incidence of nausea was 15%. All patients were ready for hospital discharge within one hour following treatment.

Conclusions

Patient maintained alfentanil TCI provides good analgesia for ESWL in the majority of patients with little sedation. Respiratory depression is uncommon but supplementary oxygen should be given prophylactically. There is considerable interindividual variation in demand for alfentanil indicating the usefulness of the patient control method. The TCI system underestimated alfentanil blood concentrations but this did not affect its clinical usefulness.  相似文献   
72.
PURPOSE: This study examined the effectiveness of early and prolonged mu4D5 (the murine form of trastuzumab/Herceptin) treatment in transgenic mice that overexpress human HER2 (huHER2), under the murine mammary tumor virus promoter, as a model of huHER2-overexpressing breast cancer. EXPERIMENTAL DESIGN: Mice were randomly assigned to one of three treatment groups and received i.p. injections from 17 weeks of age until either 52 weeks of age or morbidity. Fourteen mice received 100 mg/kg mu4D5, 14 mice received 100 mg/kg antiherpes simplex virus glycoprotein D control antibody, and 11 mice received a diluent control. RESULTS: High levels of huHER2 expression were detectable in mammary glands of young virgin founder mice. Mammary adenocarcinomas were frequently found in female founders and progeny at an average age of 28 weeks, with some progressing to metastatic disease. The incidence of mammary tumors was significantly reduced, and tumor growth inhibition was observed in mice receiving mu4D5 compared with control mice. In addition, Harderian gland neoplasms, highly associated with overexpression of huHER2 in this transgenic line, were entirely absent in the mu4D5 treatment group, indicating down-regulation of huHER2 in vivo activity. CONCLUSIONS: Early intervention with mu4D5 was of benefit in our transgenic mice at high risk for developing huHER2-overexpressing breast cancer. This study suggests a potential benefit of early treatment with Herceptin in HER2-positive primary breast cancer.  相似文献   
73.
74.
75.
BACKGROUND/OBJECTIVE: The incidence of head/neck trauma preceding cervical dystonia (CD) has been reported to be 5-21%. There are few reports comparing the clinical characteristics of patients with and without a history of injury. Our aim was to compare the clinical characteristics of idiopathic CD (CD-I) to those with onset precipitated by trauma (CD-T). METHODS: We evaluated 114 consecutive patients with CD over a 9-month period. All patients were interviewed using a detailed questionnaire and had a neurological examination. Their clinical charts were also reviewed. RESULTS: Fourteen patients (12%) had mild head/neck injury within a year preceding the onset of CD. Between the two groups (CD-I and CD-T), the gender distribution (F:M of 3:2), family history of movement disorders (32% vs. 29%), the prevalence of gestes antagonistes (65% vs. 64%), and response to botulinum toxin were similar. There were non-specific trends, including an earlier age of onset (mean ages 43.3 vs. 37.6), higher prevalence of neck pain (86% vs. 100%), head tremor (67% vs. 79%), and dystonia in other body parts (23% vs. 36%) in CD-T. CONCLUSIONS: CD-I and CD-T are clinically similar. Trauma may be a triggering factor in CD but this was only supported by non-significant trends in its earlier age of onset.  相似文献   
76.
荨麻水溶性化学成分研究   总被引:13,自引:0,他引:13       下载免费PDF全文
王梦月  李外  李晓波 《中国药学杂志》2005,40(24):1853-1855
 目的 研究荨麻的水溶性化学成分。方法 运用大孔树脂、聚酰胺柱色谱、硅胶柱色谱等方法对荨麻水溶性化学成分 进行分离;运用UV,IR,MS,NMR等方法进行结构鉴定。结果 从荨麻全草中分离并鉴定了7个化合物,分别为硝酸钾(potassi- um nitrate,Ⅰ)、异鼠李素(isorhamnetin,Ⅱ)、山柰酚-7-O-β-D-吡喃葡萄糖苷(kaempferol-7-O-β-D-glucopyranoside,Ⅲ)、槲皮素-7-O-β-D-吡喃葡萄糖苷(quercetin-7-O-β-D-glucopyranoside,Ⅳ)、异鼠李素-3-O-β-D-芸香糖苷(isorhamnetin-3-O-β-rutinoside,Ⅴ)、3,5-二 咖啡酰奎宁酸(3,5-di-O-caffeoylquinic acid,Ⅵ)、芦丁(rutin,Ⅶ)。结论 化合物Ⅱ-Ⅶ均为首次从荨麻中分得,其中Ⅳ,Ⅴ为首 次从荨麻属中分得。  相似文献   
77.
Horizontal stereotactic core biopsy can be used in the investigation of clinically occult mammographic abnormalities especially when breast thickness is less than 3 cm. We designed a 6-mm plastic slot that can be inserted between the bushing and the biopsy gun to enhance the accuracy of needle placement within the lesion. With this device, the centre of the lesion can be targeted at the centre of the biopsy trough. We advocate the use of this piece of small, simple and inexpensive instrument in every case of horizontal stereotactic core biopsy.  相似文献   
78.
国际多中心临床试验的监查   总被引:2,自引:0,他引:2  
为贯彻临床试验管理规范,保证多中心临床试验的质量。本文以ADVANCE多中心临床试验为例,简介监查的程序和方法。提出监查员应当具有医药知识和临床试验经验,应当按程序到研究点去核查CRF,研究文件和有关资料。标准化的监查有助于提高多中心临床试验的质量。  相似文献   
79.
80.
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