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   12318篇
  免费   837篇
  国内免费   39篇
耳鼻咽喉   108篇
儿科学   409篇
妇产科学   235篇
基础医学   1467篇
口腔科学   255篇
临床医学   1298篇
内科学   2787篇
皮肤病学   83篇
神经病学   1097篇
特种医学   397篇
外科学   1964篇
综合类   174篇
一般理论   3篇
预防医学   995篇
眼科学   523篇
药学   677篇
中国医学   26篇
肿瘤学   696篇
  2022年   60篇
  2021年   144篇
  2020年   103篇
  2019年   184篇
  2018年   196篇
  2017年   139篇
  2016年   176篇
  2015年   219篇
  2014年   323篇
  2013年   459篇
  2012年   631篇
  2011年   789篇
  2010年   430篇
  2009年   395篇
  2008年   712篇
  2007年   806篇
  2006年   808篇
  2005年   767篇
  2004年   796篇
  2003年   778篇
  2002年   656篇
  2001年   113篇
  2000年   96篇
  1999年   110篇
  1998年   146篇
  1997年   137篇
  1996年   115篇
  1995年   119篇
  1994年   99篇
  1993年   94篇
  1992年   111篇
  1991年   84篇
  1990年   69篇
  1989年   70篇
  1988年   62篇
  1987年   91篇
  1986年   87篇
  1985年   87篇
  1984年   120篇
  1983年   115篇
  1982年   133篇
  1981年   115篇
  1980年   125篇
  1979年   56篇
  1978年   66篇
  1977年   77篇
  1976年   61篇
  1975年   44篇
  1974年   55篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
OBJECTIVE: We evaluated the utility of neopterin and quinolinic acid (QUIN) as surrogate measures of disease activity in juvenile idiopathic inflammatory myopathies (IIMs). METHODS: Plasma and first morning void urine samples were measured for neopterin and QUIN using commercial ELISA, HPLC, or gas chromatography-mass spectrometry in 45 juvenile IIM patients and 79 healthy controls. Myositis disease activity assessments were obtained. RESULTS: Plasma and urine neopterin and QUIN concentrations were increased in juvenile IIM patients compared with healthy controls (P <0.017). Urine neopterin and QUIN highly correlated with each other (r(s) = 0.73; P <0.0001). Urine neopterin and QUIN correlated moderately with myositis disease activity assessments, including physician and parent global activity assessments, muscle strength testing, functional assessments (Childhood Myositis Assessment Scale, Childhood Health Assessment Questionnaire), skin global activity, and edema on magnetic resonance imaging (r(s) = 0.42-0.62; P <0.05), but generally not with muscle-associated enzymes in serum. Urine neopterin or QUIN, in combination with either serum lactate dehydrogenase (LD) or aspartate aminotransferase (AST), significantly predicted global disease activity (R(2) =0.40-0.56; P <0.002), and both were more sensitive to change than these serum enzymes (standardized response means, -0.41 to -0.48). CONCLUSIONS: Urinary neopterin and QUIN are candidate measures of disease activity in juvenile IIM patients and add significantly to the prediction of global disease activity in combination with serum LD or AST values. Measurement of these markers in first morning void urine specimens appears to be as good as, or possibly better than, measurements of their concentrations in plasma.  相似文献   
993.
994.
A procedure has been developed for the determination of the concentration of infective Newcastle disease virus (NDV) based on the enumeration of singly infected and distributed HeLa cells which are visualized by staining with fluorescent antibody. Infective virus assayed by the fluorescent cell-counting procedure is expressed in terms of cell-infecting units (CIU). Adsorption of NDV to HeLa cell monolayers reached a plateau 1 to 1.5 hours after inoculation of coverslip cultures, and 12 per cent of the infective particles inoculated failed to adsorb. The half-life of NDV in protein-free Eagle's medium at 37°C. was 2.1 hours. There was a linear relationship between virus concentration and the number of infected cells. The coefficient of variation of the mean of replicate determinations of infective NDV was 8.2 per cent. The distribution of single infected HeLa cells in the monolayer corresponded to the Poisson distribution. With NDV the cell-infecting unit (CIU) determined in HeLa cells is equivalent to the plaque-forming unit in chick embryo cells and the egg infective dose. In experiments on the mechanism of dissemination of NDV in monolayer cultures of HeLa cells, NDV was found to spread from cell to cell through the extracellular milieu.  相似文献   
995.
996.
997.
998.
INTRODUCTION: On 21 September, 1999, an earthquake measuring 7.3 on the Richter scale, struck central Taiwan near the town of Chi-Chi. The event resulted in 2,405 deaths and 11,306 injuries. Ad hoc emergency medical assistance teams (EMATs) from Taiwan assumed the responsibility for initiating early assessments and providing medical care. OBJECTIVE: To determine whether the EMATs served a key role in assisting critically injured patients through the assessment of number and level of hospitals responding, training background, timeliness of response, and acuity of patient encounters. METHODS: Local and national health bureaus were contacted to identify hospitals that responded to the disaster. A comprehensive questionnaire was piloted and then, sent to those major medical centers that dispatched EMATs within the first 72 hours following the quake. In-depth interviews also were conducted with team leaders. RESULTS: A total number of 104 hospitals/clinics responded to the disaster, including nine major medical centers and 12 regional hospitals. Each of the major medical centers/regional hospitals that dispatched EMATs during the first 72 hours following the quake were surveyed. Also, 20 individual team leaders were interviewed. Seventy-nine percent of the EMATs from the hospitals responded spontaneously to the scene, while only 21% were dispatched directly by national or local health authorities. Combining the phases of the disaster response, it is estimated that only 7% of EMATs were providing on-site care within the first 12 hours following the earthquake, 17% within < 18 hours, and 20% within < 24 hours. Thus, 80% of these EMATs required > 24 hours to respond to the site. Based on a ED I-IV triage system (Level-I, highest acuity; Level-IV, lowest acuity), the vast majority of patient encounters consisted of Level-III and Level-IV patients. Fewer than 16% of teams encountered > 10 Level-I patients, and < 28% of teams evaluated > 10 Level-II patients. CONCLUSIONS: 1. The response from EMATs was impressive, but largely uncoordinated in the absence of a pre-existing dispatching mechanism. 2. Most of the EMATs required > 24 hours to reach the disaster sites, and generally, did not arrive in time of affect the outcome of victims with preventable deaths. Therefore, there is an urgent need to strengthen local prehospital care. 3. A central governmental body that ensures better horizontal and vertical integration, and a comprehensive emergency management system is required in order to improve future disaster response and mitigation efforts.  相似文献   
999.
Samples in prior studies examining attachment theory in the military have been predominantly composed of male combat veterans. Given the rates of sexual trauma among female veterans and differences in the association between attachment and posttraumatic stress disorder (PTSD) severity for sexual trauma survivors, it was necessary to consider the attachment characteristics of veterans within a mixed‐sex sample. Participants were a mixed‐sex veteran sample seeking inpatient trauma‐related treatment (N = 469). Using independent samples t tests, we examined sex differences in attachment. Consistent with our hypothesis, women reported a higher level of attachment anxiety than did men, t(351) = ?2.12, p = .034. Women also reported a higher level of attachment avoidance, t(351) = ?2.44, p = .015. Using hierarchical regression, we examined the contribution of attachment anxiety and avoidance to PTSD severity, partialing out variance accounted for by demographic variables and traumatic experiences. Consistent with our hypotheses, attachment avoidance predicted PTSD severity on the Clinician‐Administered PTSD Scale for DSM‐IV (CAPS), β = .20, p < .001, and the PTSD Checklist–Civilian Version (PCL‐C), β = .18, p < .001. Attachment anxiety did not predict CAPS severity but did predict PCL‐C severity, β = .11, p = .020. These results suggest the association between attachment avoidance and PTSD is not exclusive to combat trauma and may apply more generally to the larger veteran population. Higher levels of attachment anxiety and avoidance among female veterans potentially implicate the presence of greater attachment fearfulness among this particular subpopulation of veterans.  相似文献   
1000.
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