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   12620篇
  免费   1293篇
  国内免费   42篇
耳鼻咽喉   261篇
儿科学   374篇
妇产科学   291篇
基础医学   1642篇
口腔科学   338篇
临床医学   1528篇
内科学   2734篇
皮肤病学   188篇
神经病学   942篇
特种医学   494篇
外科学   1752篇
综合类   353篇
一般理论   7篇
预防医学   1315篇
眼科学   207篇
药学   897篇
中国医学   6篇
肿瘤学   626篇
  2021年   176篇
  2020年   132篇
  2019年   185篇
  2018年   190篇
  2017年   178篇
  2016年   153篇
  2015年   221篇
  2014年   255篇
  2013年   393篇
  2012年   535篇
  2011年   540篇
  2010年   285篇
  2009年   271篇
  2008年   464篇
  2007年   534篇
  2006年   497篇
  2005年   498篇
  2004年   477篇
  2003年   500篇
  2002年   454篇
  2001年   389篇
  2000年   468篇
  1999年   354篇
  1998年   179篇
  1997年   139篇
  1996年   151篇
  1995年   131篇
  1994年   123篇
  1993年   105篇
  1992年   299篇
  1991年   296篇
  1990年   273篇
  1989年   290篇
  1988年   247篇
  1987年   229篇
  1986年   267篇
  1985年   237篇
  1984年   193篇
  1983年   148篇
  1982年   131篇
  1979年   186篇
  1978年   118篇
  1977年   124篇
  1976年   103篇
  1975年   118篇
  1974年   145篇
  1973年   136篇
  1972年   141篇
  1971年   121篇
  1970年   110篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
The techniques specific to peroperative fluorocholangiography are discussed based on an experience of 632 cholangiograms and an estimation has been made of the associated radiation doses to staff and patients. Rapid and accurate information can be obtained during fluorocholangiography using appropriate techniques with acceptably low radiation hazards.  相似文献   
12.
13.
14.
After nearly a year of preparation, 'Therapeutic Communication', the first nursing unit in our new Bachelor of Nursing degree was taught for the first time in 1988. The unit has developed and grown since this time, with both educational and financial factors determining such things as design of student materials and assessment mode. The geographically scattered--and often isolated--students are formally recognised for their individuality and their personal and professional life experiences, and given choices within the unit of what they want to learn and how they will present this material, through introduction of a learning contract as part of the unit assessment. Difficulties encountered by these students in maintaining their self-esteem when moving from the demanding and complex world of clinical nursing to the arena of tertiary study are discussed. The provision of speedy, comprehensive feedback with general as well as specific guidance with essay writing and referencing, focuses on the process skills many nurses lack as they enter this unit. The applicability of therapeutic communication to clinical practice and the diversity of projects undertaken by students within the limits of the unit demonstrate its appeal to a wide range of registered nurses. Some of the often ignored or minimised factors that differentiate external study from on-campus work are highlighted for both students and unit facilitator, and the creation of an in-house booklet to assist students in developing their skills in external study is outlined.  相似文献   
15.
The development of the brachial spinal cord was studied in the marsupial Macropus eugenii (tammar wallaby) on postnatal days 1-34. On day 1 the spinal cord was histologically immature, with a deep central canal, proliferating neuroepithelium and roof and floor plates. The lateral motor column had formed, and forelimb muscles contained primary myotubes. The spinal cord gradually attained a mature appearance between days 1-34. The results confirm the suitability of the wallaby spinal cord for studies of early mammalian development.  相似文献   
16.
17.
18.
PURPOSETo document differences in the cerebral proton MR spectra of patients with early and late stages of human immunodeficiency virus (HIV) infection.METHODWe studied the relative N-acetyl-aspartate (NAA) levels by localized proton spectroscopy of the parietooccipital region of the brain in 43 HIV-seropositive patients, including 26 with an acquired immunodeficiency syndrome (AIDS)-defining diagnosis, and in eight control subjects.RESULTSReduced relative NAA levels were shown in those HIV-1-seropositive patients: 1) with AIDS against HIV-1-seropositive patients without AIDS (P < .04); 2) with HIV-1-associated cognitive/motor complex against neurologically healthy patients (P < .007); 3) with encephalopathic changes on MR against those with normal imaging (P < .001); and 4) on follow-up against their results on initial study (P < .03).CONCLUSIONSBy clinical (Centers for Disease Control classification) and radiologic (MR evidence of white-matter disease) criteria indicating late-stage HIV infection, reduced relative levels of NAA have been demonstrated. Spectroscopic abnormalities can be quantitatively tracked with time. This paper demonstrates the clinical use of detecting NAA as a putative in vivo measure of the neuronal loss that has been demonstrated in postmortem studies of patients with AIDS. This neuronal loss, which is believed to underlie the HIV-1-associated cognitive/motor complex, is thought to be attributable directly or indirectly to the presence of HIV in the brain. Proton spectroscopy may serve as a quantitative noninvasive indicator of this aspect of cerebral involvement in HIV disease.  相似文献   
19.
Summary We enrolled children with acute lymphoblastic leukemia (ALL) in a Pediatric Oncology Group (POG) pilot study to monitor erythrocyte (RBC) methotrexate (MTX) and folate (F) levels before and during treatment. The mean value for RBCF at diagnosis was 0.86±0.46 nmol/ml RBC in the 214 patients who achieved remission and 1.21±0.74 nmol/ml RBC in the 10 patients who did not (P=0.020). Folate levels tended to increase during remission induction, but they dropped following an intensive consolidation with methotrexate to levels that were sustained throughout chemotherapy treatment. Methotrexate levels reached mean values of approximately 0.15 nmol/ml RBC at the end of an intensive methotrexate consolidation, then fell to levels that were sustained throughout maintenance therapy. There was a weak correlation between improved event-free survival and higher RBCMTX levels after consolidation, but no correlation was found between improved survival and the level of RBCMTX or RBCF during maintenance therapy. A larger study with more complete data is needed to determine whether RBCMTX or RBCF might be useful in predicting event-free survival in patients with ALL.This work was supported in part by grants from the National Cancer Institute and the National Institute of Health (CA-30969, CA-28476, CA29139, CA-159-89, and CA-33587)  相似文献   
20.
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