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   6129篇
  免费   547篇
  国内免费   20篇
耳鼻咽喉   74篇
儿科学   188篇
妇产科学   143篇
基础医学   836篇
口腔科学   130篇
临床医学   595篇
内科学   1308篇
皮肤病学   98篇
神经病学   347篇
特种医学   210篇
外科学   964篇
综合类   156篇
一般理论   5篇
预防医学   599篇
眼科学   150篇
药学   358篇
中国医学   10篇
肿瘤学   525篇
  2022年   40篇
  2021年   130篇
  2020年   60篇
  2019年   104篇
  2018年   162篇
  2017年   110篇
  2016年   113篇
  2015年   130篇
  2014年   186篇
  2013年   250篇
  2012年   384篇
  2011年   363篇
  2010年   222篇
  2009年   212篇
  2008年   344篇
  2007年   353篇
  2006年   308篇
  2005年   334篇
  2004年   360篇
  2003年   276篇
  2002年   289篇
  2001年   117篇
  2000年   123篇
  1999年   95篇
  1998年   61篇
  1997年   58篇
  1996年   69篇
  1995年   54篇
  1994年   49篇
  1993年   45篇
  1992年   85篇
  1991年   98篇
  1990年   67篇
  1989年   82篇
  1988年   70篇
  1987年   85篇
  1986年   62篇
  1985年   58篇
  1984年   50篇
  1983年   49篇
  1982年   56篇
  1981年   39篇
  1980年   44篇
  1979年   40篇
  1978年   41篇
  1977年   40篇
  1975年   29篇
  1974年   30篇
  1972年   29篇
  1970年   26篇
排序方式: 共有6696条查询结果,搜索用时 31 毫秒
81.
We reviewed the results of percutaneous intervention of hilar biliary malignancy over a 10‐year period at a single institution: the Royal Melbourne Hospital. Ninety‐nine patients (100 treated in total) were included. Information was retrieved by retrospective examination of patient notes and radiology, combined with interviews with family and relevant physicians. Sixty‐nine patients were treated with insertion of semipermanent stents, 19 had external drain tubes, and 25 received percutaneous access for Iridium brachytherapy. Adequate drainage was achieved in 87% of the patients stented, and percutaneous access was successful in 96% of patients planned for brachytherapy. Of those patients undergoing endoprosthesis insertion, early complications occurred in 39% and late complications in 23%. Average survival for the entire patient population was 227.3 days, with a median of 167 days. Longer survival times (213 vs 142 days) and lower complication rates (44 vs 64%) are observed with metal stents in comparison with plastic stents. Percutaneous intervention is an important treatment option in hilar biliary malignancy, particularly in patients unfit for surgery. Reasonable survival with good palliation is the most common outcome, and most patients do not require further intervention.  相似文献   
82.
83.
To examine whether endogenous androgens influence the occurrence of prostate cancer, we conducted a nested case-control study among participants enrolled in the Carotene and Retinol Efficacy Trial. We analyzed serum samples of 300 cases diagnosed between 1987 and 1998, and 300 matched controls. Higher concentrations of testosterone (T) were not associated with increased prostate cancer risk. Relative to men with levels in the lowest fourth of the distribution, men in the upper fourth of total T had a risk of 0.82 [95% confidence interval (CI), 0.52-1.29]. The corresponding relative risks for free T (0.72; 95% CI, 0.45-1.14), percentage of free T (0.74; 95% CI, 0.46-1.19), and total T:sex hormone binding globulin ratio (0.52; 95% CI, 0.32-0.83) similarly were not elevated. Higher concentrations of androstenedione, dehydroepiandrosterone sulfate, and 3 alpha-androstanediol glucuronide were weakly associated with risk. Relative risks associated with being in the highest fourth for androstenedione, dehydroepiandrosterone sulfate, and 3 alpha-androstanediol glucuronide were 1.20 (95% CI, 0.76-1.89), 1.38 (95% CI, 0.86-2.21), and 1.27 (95% CI, 0.80-2.00), respectively. Men in the upper fourth of total estradiol (E2), free E2 and percentage of free E2 had relative risks of 0.71 (95% CI, 0.42-1.13), 0.52 (95% CI, 0.33-0.82), and 0.65 (95% CI, 0.40-1.05), respectively. The inverse association between E2 and prostate cancer risk was largely restricted to men with blood collection within 3 years of diagnosis. Our results add to the evidence that serum testosterone is unrelated to prostate cancer incidence. The suggestions that intraprostatic androgen activity may increase risk and that serum estrogens may decrease risk, warrant additional study.  相似文献   
84.
Although transjugular liver biopsies are frequently performed in patients with impaired blood coagulation, their impact on effecting changes in clinical management has not been assessed. We reviewed our experience with 43 consecutive transjugular liver biopsies performed over 3 years (1998?2000) at Westmead Hospital, Sydney, Australia. The technical success, procedural complication rates and subsequent management of these patients were ascertained from the medical case records. Forty‐two (28 men) patients were studied. The indications for liver biopsy were as follows: assessment of hepatitis/cirrhosis status (n = 21), evaluation of liver dysfunction following bone marrow transplantation (n = 19) and miscellaneous (n = 2). All liver biopsies were performed with a Cook 20‐G transjugular cutting needle device. Adequate histological samples were obtained in 42 (98%) of the 43 biopsies performed. The pre‐biopsy diagnoses were confirmed by histology in 28 cases (65%). A change in clinical diagnosis was observed in 12 (28%) patients, and there were changes to subsequent management in all 12 patients. Four patients developed procedural complications, including small neck haematomas in two patients and a self‐limiting biliary fistula in one. The only major complication was an extracapsular bleed from a hepatic laceration. This patient required emergency surgery but recovered. Transjugular liver biopsies can be effectively and safely performed in high‐risk patients with impaired coagulation. They aid accurate histological appraisal of liver dysfunction in these patients and influence clinical decision‐making.  相似文献   
85.
86.
Patients who are approached to participate in clinical studies just before delivery may have insufficient time to make an informed decision and/or may feel pressured into participation. This study was designed to examine factors that influence parturients to consent or decline participation in an anesthesia study related to their delivery. Parturients who had been approached to participate in a continuing clinical obstetric anesthesia study were subsequently given a questionnaire that documented their reasons for consenting or declining participation. There were no demographic differences among the consenters (n = 166) and nonconsenters (n = 109). The most important factors in the patient's decision to consent were related to their understanding and perceived importance of the study and the potential benefit to other women. Forty-one (40. 6%) nonconsenters strongly considered their pain/discomfort a factor in declining participation. Only one patient felt some pressure to consent, suggesting that the overall environment was noncoercive. Logistic regression analysis demonstrated that patients who read the consent form completely, those who had participated in a previous research study, and those who were less anxious about participating were more likely to consent. Implications: Obtaining informed consent for obstetric anesthesia studies presents a challenge to the anesthesiologist. Results from this study suggest that the environment in which consent for obstetric studies is sought is not coercive. However, it is important that the anesthesiologist ensures that the patient fully understands the study and develops a rapport with the patient to allay any anxiety associated with her participation as a potential research subject.  相似文献   
87.
88.
89.
90.
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