首页 | 官方网站   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   24548篇
  免费   2101篇
  国内免费   35篇
医药卫生   26684篇
  2023年   233篇
  2022年   160篇
  2021年   936篇
  2020年   553篇
  2019年   860篇
  2018年   997篇
  2017年   618篇
  2016年   626篇
  2015年   716篇
  2014年   980篇
  2013年   1493篇
  2012年   1768篇
  2011年   1707篇
  2010年   903篇
  2009年   749篇
  2008年   1195篇
  2007年   1234篇
  2006年   1107篇
  2005年   963篇
  2004年   967篇
  2003年   749篇
  2002年   709篇
  2001年   449篇
  2000年   511篇
  1999年   425篇
  1998年   188篇
  1997年   159篇
  1996年   147篇
  1995年   125篇
  1994年   108篇
  1993年   114篇
  1992年   292篇
  1991年   272篇
  1990年   261篇
  1989年   280篇
  1988年   274篇
  1987年   232篇
  1986年   291篇
  1985年   200篇
  1984年   185篇
  1983年   155篇
  1982年   112篇
  1981年   130篇
  1980年   119篇
  1979年   203篇
  1978年   134篇
  1977年   95篇
  1976年   109篇
  1975年   100篇
  1974年   105篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
We report the attempt to set up a mini sports medicine clinic in a health centre resourced by a Department of Community Medicine. The type of problems seen are similar to those reported by other clinics. On the results of this pilot project, we believe it would be possible to establish similar clinics in health centres elsewhere in the United Kingdom. The National Health Service resources required are minimal, but the benefits to local communities are considerable.  相似文献   
72.
D Ryan 《Military medicine》1992,157(5):266-268
The expansion of technology has allowed patients to receive intravenous therapy at home. This case study discusses the problems of a patient with diabetes mellitus and malignant otitis externa. This patient received intravenous therapy for the last 3 years of his life. In spite of several hospitalizations, he was able to return and remain home until his death. Management of the patient's discharge and home care seemed to be a major factor in his ability to remain in the community.  相似文献   
73.
Chronic low back pain: comparison of bone SPECT with radiography and CT   总被引:1,自引:0,他引:1  
Ryan  PJ; Evans  PA; Gibson  T; Fogelman  I 《Radiology》1992,182(3):849
  相似文献   
74.
Male cricket frogs (Acris crepitans) produce a broad-band, high frequency advertisement call with a single spectral peak (the dominant frequency). We measured the dominant frequencies of male calls from six populations in central Texas and one from Indiana and compared them to the tuning of basilar papilla afferents in males and females. Averaging over all populations, mean call dominant frequency was 3.69 kHz, mean male basilar papilla tuning was 3.63 kHz, and mean female basilar papilla tuning was 3.17 kHz. Among populations, mean dominant frequency varied from 3.56 kHz to 3.82 kHz. Dominant frequencies were slightly higher in the more eastern Texas populations occupying pine forest habitats than in the more western populations occupying open grassland habitats. Changes in dominant frequency in a population coincided with changes in tuning of both male and female basilar papillae. Furthermore, within populations females were tuned on average lower than males and lower than the mean dominant frequency of calls in their own population. We suggest that the coincident changes in calls and basilar papilla tuning plus the sexual difference in tuning indicate that female mate choice would be directed toward males from her home population with low frequency calls or toward males from foreign populations with average calls lower in frequency than those in her home population. This in turn suggests that any gene flow between populations would be biased from east to west and from forest to open habitats.  相似文献   
75.
This study reviewed a series of patients with Crohn's disease managed by surgeons of the Department of Colon and Rectal Surgery, St Vincent's Hospital, Melbourne, since 1978. There were 306 patients: 171 males and 135 females. The mean age at diagnosis was 33.4 years (range 11–93). The distribution of the disease was small bowel 32.3%, small bowel and colon 26.5%, colon 39.9%, and anal disease alone 1.6%. A total of 416 abdominal operations were performed on 204 patients. The commonest indications for surgery were failed medical therapy (21.9%), small bowel obstruction (15.9%), enteric tistula (10.1%), and intra-abdominal abscess (10.1%). The most frequently performed procedures were ileocolic resection with anastomosis (28.8%), small bowel resection (9.4%), and total colectomy and ileostomy (7.0%). Postoperative complications included anastomotic leaks in 4.0%. intra-abdominal abscess formation in 3.6%, and enterocutaneous fistulae developed in 6%. Three patients died during the review period. During follow up (mean 84.4). 30% of patients developed recurrence requiring further surgery at a mean of 72.7 months postoperatively. The most frequent site for a recurrence was the pre-anastomotic terminal ileum (61.7%). In conclusion. the majority of patients with Crohn's disease will require resectional surgery at some stage. This can be performed with a low mortality and morbidity, and a recurrence rate of around 5% per year.  相似文献   
76.
Formation of drusen in the human eye   总被引:3,自引:0,他引:3  
Light and electron microscopy of drusen formation in the human eye showed yellow-white spots in the fundus with two morphologic patterns: that of typical drusen and a nodular accumulation of cellular components beneath the retinal pigment epithelial cells. By electron microscopy, the progression of drusen formation could be classified into four stages. Stage I showed budding or evagination of retinal pigment epithelial cells into the subpigment epithelial space. This evaginated portion was connected to the retinal pigment epithelial cell cytoplasm and was surrounded by its basement membrane. In Stage II the evaginated portion of the cell was completely separate from the cytoplasm of its parent retinal pigment epithelial cell. In Stage III, the evaginated portion showed degeneration and disintegration. Finally, in Stage IV, an accumulation of vesicular, granular, tubular, and linear material was seen free within the nodular space beneath the retinal pigment epithelial cell.  相似文献   
77.
Diagnosis of dementia needs to be complemented by precise determination of disease severity across the broad spectrum of disease progression. The Mini-Mental State Exam (MMS), the Activities-of-Daily-Living assessment (ADL) and the Clinical Dementia Rating scale (CDR) were modified for direct comparability and administered to 112 outpatients and 45 nursing home residents with a range of dementia severity from mild to profound. The scales showed the highest correlations for the probable Alzheimer's disease patient group (62) (Global Assessment of Dementia; GAD vs. ADL: r = 0.91; Extended Mini-Mental Assessment; EMA vs. GAD: r = 0.91; ADL vs. EMA: r = 0.86). For these patients, scores on the individual scales tended to be similar. Disparity among the three scores for individual cases was associated with the presence of comorbidities. The high correlations and correspondence among these scales demonstrate their reliability, validity, and utility in the assessment of dementia severity. The use of an average of these measures, with their increased precision, may give a more accurate indication of dementia severity over a broader range of impairment.  相似文献   
78.
目的 了解上海地区学生午餐营养及供应链状况,为改善学生午餐营养状况,保障食品供应安全提供参考。方法 分析上海市学生午餐的营养、卫生、供应链、加工工艺等状况,采用定期抽检的方法,应用SNHAS对营养素、食品安全、感官进行综合评价。结果 各单位样本综合评价均合格,其中热量、蛋白质、脂肪均能达到或超过DRIs供给量的要求,但矿物质中Ca(仅为AI的32%)、视黄醇当量(仅为AI的57%)供给量较低。对供应链及卫生状况的分析表明,大型企业对各个环节控制严格,产品质量较好,但也存在保存时间过长等问题。结论 应进一步完善供应体系,建立高效的质量控制体系,推广营养配膳系统。  相似文献   
79.
Macrophage infiltration is frequent in the early stages of various proliferative eye disorders, including subretinal neovascularization. In this study, we set out to establish the origin of macrophages found in an animal model of laser-induced subretinal neovascularization. One primate received several intravenous injections of a colloidal carbon suspension. We then applied standard argon laser lesions to the retina of both eyes, which were enucleated eight days later and sectioned serially for histological examination. A quantitative estimate of carbon-laden and non-laden leukocytes was made based on morphological criteria. Mononuclear leukocytes accumulated in the laser lesions and the percentage of carbon-laden mononuclear leukocytes in relation to the total leukocyte number was higher in the extravascular area of the laser sites than in the systemic circulation. These findings indicate that the majority of mononuclear leukocytes that accumulate at the sites of laser lesions are derived from the systemic circulation.  相似文献   
80.
Collaborative Practice provides a forum for healthcare professionals to share expertise and enhance communication.  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-23

京公网安备 11010802026262号