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   1629篇
  免费   67篇
  国内免费   3篇
耳鼻咽喉   12篇
儿科学   27篇
妇产科学   16篇
基础医学   182篇
口腔科学   346篇
临床医学   83篇
内科学   287篇
皮肤病学   18篇
神经病学   91篇
特种医学   57篇
外科学   158篇
综合类   6篇
预防医学   240篇
眼科学   47篇
药学   86篇
中国医学   18篇
肿瘤学   25篇
  2023年   14篇
  2022年   16篇
  2021年   58篇
  2020年   39篇
  2019年   40篇
  2018年   46篇
  2017年   38篇
  2016年   31篇
  2015年   38篇
  2014年   56篇
  2013年   86篇
  2012年   101篇
  2011年   132篇
  2010年   83篇
  2009年   58篇
  2008年   90篇
  2007年   102篇
  2006年   91篇
  2005年   73篇
  2004年   64篇
  2003年   58篇
  2002年   57篇
  2001年   28篇
  2000年   29篇
  1999年   18篇
  1998年   20篇
  1997年   17篇
  1996年   11篇
  1995年   9篇
  1994年   7篇
  1993年   13篇
  1992年   7篇
  1991年   8篇
  1990年   8篇
  1989年   12篇
  1988年   12篇
  1987年   11篇
  1986年   6篇
  1985年   20篇
  1984年   6篇
  1981年   5篇
  1979年   8篇
  1975年   9篇
  1973年   8篇
  1972年   4篇
  1970年   4篇
  1969年   5篇
  1968年   6篇
  1967年   8篇
  1965年   4篇
排序方式: 共有1699条查询结果,搜索用时 125 毫秒
1.
2.
The authors present a synthesis of the proposals put forth by the health sector of Venezuela during the framing of the new Venezuelan Constitution. They summarize the background to the National Constituent Assembly and the legal framework typical of the health sector at that time, identify the methodological aspects that substantiated the health topics included in the new Constitution, and analyze the articles that shape the current constitutional health framework in Venezuela, summarizing their most important features and comparing them with neoliberal health proposals.  相似文献   
3.
4.
5.
6.
To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.  相似文献   
7.
Autopsy findings of missed diagnoses that would probably have changed management or prognosis occur in up to 29% of cases in general hospitals. Such proportions may be higher in subsets of patients with complex diseases. We reviewed 2908 consecutive autopsies performed over a period of 29 months in a large-volume hospital, analyzing 118 autopsies of patients with hematological malignancies or severe aplastic anemia. A review of macroscopic reports as well as microscopic examination of tissue samples was performed. Medical records were reviewed for clinical diagnoses. Discordances between clinical and autopsy diagnoses were classified using Goldmans criteria. Additionally, we searched for clinical parameters correlated with occurrence of class-I discrepancy using a multivariate method. Median age was 46.5 years, and 25.4% had received a hematopoietic stem-cell transplant. Overall, 11.9% (6.6–19.1%) of patients died before conclusion of the hematological diagnosis and 33% (24.6–42.3%) died with no active hematological disease. We found class-I discrepancy in 31.3% (23.1–40.5 %) of cases. The most common among these diagnoses were hematological disease, pneumonia and gastrointestinal bleeding. In a univariate analysis, being elderly (P=0.04) was positively correlated with the finding of class-I discrepancies; while, having received previous specific hematological treatment (P=0.0005) or hematopoietic stem-cell transplants (P=0.013), or being admitted to a specialized hematology unit (P=0.0006) were negatively correlated to the occurrence of such discrepancies. Multivariate analysis showed that care in a specialized hematology unit (OR 0.34, 0.12–0.93) was independently associated with lower occurrence of discrepancies. We concluded that critical diagnoses are often missed in highly complex hematological patients especially in the absence of admission to specialized hematology units.  相似文献   
8.
Nine different inbred strains of mice inoculated intraperitoneally with yeast cells of Paracoccidioides brasiliensis showed significantly varying patterns of susceptibility. The A/SN strain was found to be the most resistant, while BIOD2/nSn, BIO.A and BIOD2/oSn the most susceptible strains. These susceptibility differences were not dependent on the size of challenge inocula and sex of animals. All strains studied showed a mean survival time proportional to the size of inocula used. Although almost all infected male mice presented a shorter survival time when compared with females, significant mortality differences between sexes were found only in two of the strains studied, namely BALB/c and BIOD2/nSn. The H-2 region did not influence the susceptibility pattern since the A/SN and BIO.A strains share the same H-2 haplotype and were respectively highly resistant and susceptible to P. brasiliensis. Furthermore, the presence of C5 and unresponsiveness to lipopolysaccharide had no influence on the mortality data observed. Specific antibodies were detected only in a small number of animals and titres were consistently low, appearing later in the resistant (A/SN) than in a susceptible strain (BIO.A). Omentum, spleen and liver were the most affected organs in both strains, but the susceptible mice had more granulomatous lesions and earlier dissemination of the fungus.  相似文献   
9.
O. G. Bier  H. C. Passos    M. Siqueira 《Immunology》1968,14(2):291-298
In guinea-pigs injected intradermally with a small amount of antibody and challenged 2 hours later, by the intravenous route, with a mixture of homologous antigen and aggregated γ-globulin, haemorrhagic reactions of the Arthus type develop at the sites of intradermal sensitization. This effect was obtained with γ-globulins of different species (human, rabbit and horse) by using different techniques for aggregation (heat, mercaptoethanol—urea and bis-diazobenzidine) and was always correlated with the ability of the aggregated globulin to fix complement.

Fluorescein labelled aggregates of γ-globulin were detectable in the wall of vessels at sensitized sites.

In experiments performed with guinea-pig antibodies, the localizing effect was observed only with γ1, whereas the γ2, Arthus-producing fraction proved completely ineffective.

Histamine and histamine liberators are not sufficient for eliciting the effect obtained with sensitizing antibody plus homologous antigen. It is postulated, therefore, that other effects occurring at the site of specific sensitization may also be responsible for the phenomenon.

  相似文献   
10.
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