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   971篇
  免费   74篇
  国内免费   7篇
耳鼻咽喉   3篇
儿科学   57篇
妇产科学   10篇
基础医学   112篇
口腔科学   30篇
临床医学   166篇
内科学   204篇
皮肤病学   13篇
神经病学   38篇
特种医学   243篇
外科学   50篇
综合类   21篇
预防医学   33篇
眼科学   7篇
药学   33篇
中国医学   5篇
肿瘤学   27篇
  2024年   3篇
  2023年   8篇
  2021年   10篇
  2020年   9篇
  2019年   6篇
  2018年   26篇
  2017年   14篇
  2016年   18篇
  2015年   21篇
  2014年   27篇
  2013年   24篇
  2012年   15篇
  2011年   17篇
  2010年   36篇
  2009年   54篇
  2008年   25篇
  2007年   9篇
  2006年   13篇
  2005年   5篇
  2004年   7篇
  2003年   13篇
  2002年   10篇
  2001年   15篇
  2000年   10篇
  1999年   13篇
  1998年   49篇
  1997年   52篇
  1996年   64篇
  1995年   48篇
  1994年   43篇
  1993年   47篇
  1992年   15篇
  1991年   7篇
  1990年   15篇
  1989年   38篇
  1988年   31篇
  1987年   34篇
  1986年   35篇
  1985年   25篇
  1984年   18篇
  1983年   10篇
  1982年   22篇
  1981年   14篇
  1980年   8篇
  1979年   6篇
  1978年   6篇
  1977年   13篇
  1976年   14篇
  1975年   15篇
  1970年   3篇
排序方式: 共有1052条查询结果,搜索用时 15 毫秒
51.
It has been suggested that proliferation of enterobacteriaceae and/or anaerobes in the duodenum of some children with acute diarrhoea determines whether the episode becomes persistent. A review of published studies and the comparison of cultures of duodenal aspirates from Peruvian children with acute and persistent diarrhoea and diarrhoea-free children did not support this hypothesis. Although many children had enterobacteriaceae and/or anaerobes cultured there was no correlation with clinical and nutritional outcome. Age, nutritional status, the environment and the aetiology of the episode were determinants of the duodenal microflora independent of diarrhoea. Culture of the duodenal aspirates did not increase the yield of enteropathogens which were isolated more frequently from stools than from the duodenum. Despite the presence of a single strain or serotype of enterobacteriaceae suggesting that these bacteria were colonizing the duodenum, we were unable to demonstrate any adherence mechanisms in the majority of them. Two often bacteria with no other evidence of virulence caused diarrhoea in the RITARD rabbit model.  相似文献   
52.
Very-low-birthweight (VLBW) neonates are more prone to complications and death than term infants are. In a 15-year period, 19 neonates with VLBW were operated on for necrotizing enterocolitis (NEC). Indications for operation were pneumoperitoneum in 12 and deterioration of general condition in 7. Bowel resection and intestinal diversion was performed in 12, a lateral enterostomy at the site of perforation was created in 5, and 2 neonates with necrosis of the whole bowel underwent an exploratory laparotomy without any further surgical treatment. Surgical complications were found in one-third of the patients. The mortality rate was significantly higher when the ileum was affected. The survival rate was 68%. Prior to 1984 the survival rate was 37% (3/8); subsequently, it has improved to 91% (10/11) as a result of improved intensive therapy.  相似文献   
53.
54.
An examination of the early events in the infection of cultured mouse embryo fibroblasts using both chymotrypsin-treated (chymo+) and untreated (chymo?) polyoma virus has shown that exposure to the protease has no effect on the ability of the virions to attach to, penetrate into, and enter the nuclei of cells. Uncoating, which our data indicate takes place exclusively in the nuclei, appears to be somewhat delayed in the case of the chymo+ virions. The only identifiable product of uncoating is a DNA protein complex having a sedimentation coefficient of the order of 52–55 S. Stimulation of cellular and viral DNA synthesis was found to be greatly reduced in cells infected with chymo+ virions relative to those infected with chymo- virions, but the specific infectivities of DNAs isolated from chymo+ and chymo? virions were found to be precisely the same.  相似文献   
55.
56.
57.
BACKGROUND: Through the 1990s, governments across Canada shifted health care funding allocation and organizational foci toward a community-based population health model. Major concerns of reform based on this model include ensuring equitable access to health and health care, and enhancing preventive and community-based resources for care. Reforms may act differentially relative to specific conditions and services, including those geared to chronic versus acute conditions. The present study therefore focuses on health service utilization, specifically cancer hospitalizations, in British Columbia during a decade of health system reform. METHODS: Data were drawn from the British Columbia Linked Health Data resource; income measures were derived from Statistics Canada 1996 Census public use enumeration area income files. Records with a discharge (separation) date between 1 January 1991 and 31 December 1998 were selected. All hospitalizations with ICD-9 codes 140 through 208 (except skin cancer, code 173) as principal diagnosis were included. Specific cancers analyzed include lung; colorectal; female breast; and prostate. Hospitalizations were examined in total (all separations), and as divided into first and all other hospitalizations attributed to any given individual. Annual trends in age-sex adjusted rates were analyzed by joinpoint regression; longitudinal multivariate analyses assessing association of residence and income with hospitalizations utilized generalised estimating equations. Results are evaluated in relation to cancer incidence trends, health policy reform and access to care. RESULTS: Age-sex adjusted hospitalization rates for all separations for all cancers, and lung, breast and prostate cancers, decreased significantly over the study period; colorectal cancer separations did not change significantly. Rates for first and other hospitalizations remained stationary or gradually declined over the study period. Area of residence and income were not significantly associated with first hospitalizations; effects were less consistent for all and other hospitalizations. No interactions were observed for any category of separations. CONCLUSIONS: No discontinuities were observed with respect to total hospitalizations that could be associated temporally with health policy reform; observed changes were primarily gradual. These results do not indicate whether equity was present prior to health care reform. However, findings concur with previous reports indicating no change in access to health care across income or residence consequent on health care reform.  相似文献   
58.
59.
Factor V deficiency has been identified in 8 of 8 patients 7--20 yr of age, with Philadelphia-positive (Ph1+) chronic myelogenous leukemia (CML). In these 8 patients, factor V deficiency was not due to hepatic dysfunction, factor V inhibitors, or disseminated intravascular coagulation. In 3 patients, factor V activity rose 10%--12% (0.10--0.12 U/ml) after the infusion of 28--31 ml/kg body weight of fresh frozen plasma (FFP). The rise persisted less than 14 hr. The mean measured postinfusion rise in factor V was 18% of the expected rise calculated from the volume of FFP infused in the patients' plasma volume. In 4 patients, a small transient rise in factor V activity occurred after splenectomy or plateletpheresis. Factor V deficiency was completely corrected after a marked reduction in bone marrow cellularity in 2 patients with Ph1+ CML treated with extensive chemotherapy, total body irradiation, and bone marrow transplantation. Factor V deficiency was retrospectively observed in 6 of 20 patients, ages 20--80 yr, with Ph1+ CML and 3 of 6 patients with other myeloproliferative disorders. The factor V deficiency appears to be associated with the large myeloid- megakaryocytic cell mass characteristic of CML and other myeloproliferative disorders.  相似文献   
60.
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