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   814篇
  免费   46篇
  国内免费   2篇
儿科学   61篇
妇产科学   9篇
基础医学   84篇
口腔科学   13篇
临床医学   99篇
内科学   159篇
皮肤病学   18篇
神经病学   34篇
特种医学   178篇
外科学   60篇
综合类   15篇
预防医学   62篇
眼科学   6篇
药学   35篇
肿瘤学   29篇
  2023年   5篇
  2021年   5篇
  2019年   4篇
  2018年   13篇
  2017年   12篇
  2016年   8篇
  2015年   6篇
  2014年   16篇
  2013年   26篇
  2012年   14篇
  2011年   21篇
  2010年   29篇
  2009年   25篇
  2008年   15篇
  2007年   17篇
  2006年   28篇
  2005年   27篇
  2004年   15篇
  2003年   24篇
  2002年   17篇
  2001年   15篇
  2000年   22篇
  1999年   19篇
  1998年   33篇
  1997年   34篇
  1996年   26篇
  1995年   29篇
  1994年   30篇
  1993年   21篇
  1992年   12篇
  1991年   16篇
  1990年   18篇
  1989年   24篇
  1988年   23篇
  1987年   25篇
  1986年   18篇
  1985年   25篇
  1984年   13篇
  1983年   10篇
  1982年   21篇
  1981年   14篇
  1980年   11篇
  1978年   6篇
  1977年   8篇
  1976年   16篇
  1975年   13篇
  1974年   3篇
  1973年   6篇
  1971年   3篇
  1970年   6篇
排序方式: 共有862条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: According to the Center for Disease Control and Prevention (CDC), an estimated 30 million people ride horses each year in the United States. Horseback riding related injuries are common, with an estimated 50,000 emergency room visits annually. The popularity of recreational horseback riding has increased in South Florida and the incidence of associated traumatic injuries is a reflection of this. MATERIAL AND METHODS: Retrospective review of patients admitted to a state designated Level I trauma center that sustained horseback riding associated injuries between January 2000 and December 2003. Information extracted from the Trauma Center's data base included demographics, mechanism of injury and toxicology screening. RESULTS: During the review period, twenty-seven patients were identified. There were 12 men and 15 women. The average age was 36 years. The injuries occurred during pleasure riding in 23 patients and thoroughbred related activities in 4 patients. Multiple severe injuries were common and documented in 24 patients. All patients required hospitalization with an average stay of 5 days. Five patients had a positive toxicology screen on admission. No deaths were documented in this review. CONCLUSION: Horseback riding related injuries tends to be serious. Alcohol and recreational drugs may contribute to exacerbate the extent of these injuries. The use of proper protective equipment, instructions for safe riding, and discouraging drug and alcohol use during riding activities should be emphasized.  相似文献   
2.
OBJECTIVES: To determine if experienced clinical educators (CEs) can improve their teaching by incorporating 4 literature-based teaching methods into their instruction. METHODS: We trained 7 experienced CEs on the teaching methods during a monthly faculty development program. Each CE recorded use of these methods during 10 months on a personal digital assistant. We compared the CEs' teaching evaluations with those of nonparticipating faculty by analysis of variance at baseline, during the study period, and for 1 year after the study. RESULTS: Reported use of 2 teaching methods (priming and feedback) increased significantly over use at baseline; use of 2 other methods (teaching in the patient's presence and 1-2 focal teaching points) remained constant. Scores on the CEs' teaching evaluations were significantly higher during the study period on 1 item, whereas the comparison group showed no changes. The changes persisted during the follow-up period. CEs reported that the teaching methods focused the learner and teacher, making subsequent encounters more productive. They also found that the act of entering data daily prompted them to reflect on their teaching. CONCLUSIONS: Experienced teachers can be persuaded to incorporate new methods into their daily teaching. Reflection on teaching is enhanced with group support and daily reminders. With these interventions, teaching effectiveness of these experienced educators improved.  相似文献   
3.
Acute appendicitis: CT and US correlation in 100 patients   总被引:19,自引:1,他引:18  
  相似文献   
4.
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm.  相似文献   
5.
We evaluated the effects of unsharp masking and highly efficient scatter rejection on film-screen chest radiographs of cancer patients. Unsharp masking significantly improved the detectability of lung nodules and visibility of anatomic structures in poorly penetrated areas of the chest. Highly efficient scatter rejection by an improved antiscatter grid provided only modest additional benefits. The study supports the conclusion that nodule detection in poorly penetrated areas on conventional chest radiographs is limited primarily by display contrast, whereas in the well-penetrated lung fields it is limited primarily by confusing background structures, rather than inadequate contrast. A method for analyzing clinical nodule detection data by transforming the FROC data to ROC coordinates also is demonstrated.  相似文献   
6.
7.
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.  相似文献   
8.
9.
Adolescence is the most formative time in the lives of women. During this time girls are making choices that have implications for the rest of their lives. Adolescence also can be a time when the negative impact of sexual and physical abuse from childhood begins to take its toll, contributing to adolescent pregnancy and substance abuse. In the last decade the incidences of pregnancy and drug use in the adolescent population have increased, with 80% of teenagers reported being sexually active by the age of 19 years and 80% of high school seniors reporting use of alcohol; 64% reporting smoking; and 41 % reporting marijuana use in 1995. Nurses working with pregnant adolescents must screen for substance abuse problems and physical abuse. If problems are identified, the nurse should refer the adolescent for counseling.  相似文献   
10.
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