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   648篇
  免费   40篇
  国内免费   34篇
儿科学   42篇
妇产科学   6篇
基础医学   69篇
口腔科学   24篇
临床医学   102篇
内科学   157篇
皮肤病学   15篇
神经病学   12篇
特种医学   119篇
外科学   44篇
综合类   15篇
预防医学   28篇
眼科学   2篇
药学   63篇
肿瘤学   24篇
  2022年   4篇
  2021年   6篇
  2020年   4篇
  2019年   6篇
  2018年   11篇
  2017年   4篇
  2016年   8篇
  2015年   13篇
  2014年   23篇
  2013年   27篇
  2012年   17篇
  2011年   11篇
  2010年   26篇
  2009年   37篇
  2008年   11篇
  2007年   29篇
  2006年   17篇
  2005年   11篇
  2004年   10篇
  2003年   8篇
  2002年   16篇
  2001年   8篇
  2000年   15篇
  1999年   25篇
  1998年   35篇
  1997年   34篇
  1996年   38篇
  1995年   24篇
  1994年   35篇
  1993年   21篇
  1992年   8篇
  1991年   7篇
  1990年   7篇
  1989年   20篇
  1988年   25篇
  1987年   12篇
  1986年   16篇
  1985年   10篇
  1984年   10篇
  1983年   7篇
  1982年   12篇
  1981年   13篇
  1980年   12篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   8篇
  1975年   7篇
  1957年   1篇
  1873年   2篇
排序方式: 共有722条查询结果,搜索用时 250 毫秒
51.
52.
An enquiry into sudden infant death syndrome (SIDS) in 1987 furnished us with detailed epidemiological data for 281 cases that underwent a thorough post-mortem examination. This analysis uses these data to evaluate the role the autopsy plays in explaining sudden death. The cases were classified into three diagnostic groups: explained causes of death (group 1), unexplained deaths with anomalies (group 2), and no anomaly (group 3). These 281 cases show the three essential features that characterize SIDS: over-representation of males, increased deaths during the second and third months of life, and increased deaths during winter. The autopsy examination revealed that many of these deaths had a medical explanation. Almost half were assigned to group 1. At the time of autopsy, no precise pathology could be diagnosed for 147 deaths; of these, 140 showed histological anomalies. There were only seven sudden deaths for which no abnormal sign was evident at the autopsy. These results are compared with those of similar studies and discussed in connection with three factors: the initial selection of cases, the nature and degree of the investigations, and the possible interpretations of the symptoms uncovered.  相似文献   
53.
54.
Studies on the development of automatic postural responses in both typically developing children and children with cerebral palsy were performed. With the appearance of "pull-to-stand" behavior, typically developing children first began to show muscle responses to platform movements in mainly the ankle muscles. With increased development, additional agonist muscles were added to the response pattern and a consistent distal to proximal sequence began to emerge. Well-organized responses were seen with the onset of independent stance and walking, along with the reduction of antagonist muscle co-activation. The older children with cerebral palsy who were pre-walkers had immature muscle activation patterns like those seen in the typically developing children at the pull-to- stand stage of development. These included disorganized muscle responses and increased frequency of coactivation of both proximal–distal and agonist–antagonist muscles. In order to determine if musculoskeletal constraints contributed to these response patterns, normal children were asked to stand in a crouched posture similar to that of children with CP. This caused postural muscle response patterns to more closely approximate those of children with spastic diplegia.  相似文献   
55.
Between 1991 and 1993, 106 newly diagnosed cases of Hirschsprung's disease (HD) were prospectively analyzed for the association of HD and intestinal neuronal dysplasia (IND) at ten pediatric surgical departments in central Europe. Hirschsprung-associated IND (HaIND) was found in 40% of cases. IND was disseminated in one-third and localized in two-thirds of the patients. Initial clinical symptoms were related to the length of the aganglionic segment, but not to the presence of HaIND. An enterostomy performed in 72 cases (67.9%) was located in a segment of pathologically innervated bowel in 50% of all cases, but in 72% of cases of HaIND. The proximal margin of the resected bowel showed pathological innervation in 44% of cases. Supplemental biopsies from the intestine (apart from diagnostic suction biopsies and biopsies at the enterostomy site) led to the first identification or definition of length of associated IND in 17.9% of cases. Postoperatively, the presence of long-segment aganglionosis or associated IND implied a delay in the restoration of normal defecation. Persistent constipation was found in 40% of patients with associated disseminated IND at follow-up at 6 months, compared to 20.6% in patients with isolated HD. These children needed secondary interventions more often than patients with associated localized IND or isolated HD. HaIND thus has clinical implications for the postoperative course if IND is disseminated. Accepted: 25 April 1999  相似文献   
56.
57.
58.
59.
60.
Background--Currently, the reporting and archiving of echocardiographic data suffer from the difficulty of representing heart motion on printable 2-dimensional (2D) media. Methods and Results--We studied the capability of holography to integrate motion into 2D echocardiographic prints. Images of normal human hearts and of a variety of mitral valve function abnormalities (mitral valve prolapse, systolic anterior motion of the mitral leaflets, and obstruction of the mitral valve by a myxoma) were acquired digitally on standard echocardiographic machines. Images were processed into a data format suitable for holographic printing. Angularly multiplexed holograms were then printed on a prototype holographic "laser" printer, with integration of time in vertical parallax, so that heart motion became visible when the hologram was tilted up and down. The resulting holograms displayed the anatomy with the same resolution as the original acquisition and allowed detailed study of valve motion with side-by-side comparison of normal and abnormal findings. Comparison of standard echocardiographic measurements in original echo frames and corresponding hologram views showed an excellent correlation of both methods (P<0.0001, r2=0.979, mean bias=2.76 mm). In this feasibility study, both 2D and 3D holographic images were produced. The equipment needed to view these holograms consists of only a simple point-light source. Conclusions--Holographic representation of myocardial and valve motion from echocardiographic data is feasible and allows the printing on a 2D medium of the complete heart cycle. Combined with the recent development of online holographic printing, this novel technique has the potential to improve reporting, visualization, and archiving of echocardiographic imaging.  相似文献   
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