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   2502篇
  免费   16篇
  国内免费   4篇
电工技术   4篇
综合类   2篇
化学工业   97篇
金属工艺   8篇
机械仪表   41篇
建筑科学   13篇
能源动力   6篇
轻工业   77篇
水利工程   1篇
无线电   29篇
一般工业技术   67篇
冶金工业   2065篇
原子能技术   4篇
自动化技术   108篇
  2023年   4篇
  2022年   14篇
  2021年   22篇
  2020年   9篇
  2019年   9篇
  2018年   11篇
  2017年   14篇
  2016年   12篇
  2015年   15篇
  2014年   11篇
  2013年   19篇
  2012年   14篇
  2011年   21篇
  2010年   24篇
  2009年   24篇
  2008年   27篇
  2007年   23篇
  2006年   21篇
  2005年   22篇
  2004年   15篇
  2003年   19篇
  2002年   21篇
  2001年   11篇
  2000年   19篇
  1999年   83篇
  1998年   623篇
  1997年   359篇
  1996年   228篇
  1995年   144篇
  1994年   104篇
  1993年   130篇
  1992年   14篇
  1991年   19篇
  1990年   16篇
  1989年   17篇
  1988年   24篇
  1987年   15篇
  1986年   16篇
  1985年   18篇
  1984年   2篇
  1983年   7篇
  1982年   8篇
  1981年   20篇
  1980年   28篇
  1978年   7篇
  1977年   69篇
  1976年   160篇
  1975年   4篇
  1964年   1篇
  1955年   3篇
排序方式: 共有2522条查询结果,搜索用时 0 毫秒
11.
Hyperferremia is shown to affect antioxidant system of the body, oxidation-reduction reactions in the cells seen as shifts in lymphocyte chemiluminescence. Dynamic changes in lymphocyte chemiluminescence reflect the level of hyperferremia.  相似文献   
12.
PURPOSE: Histology has been identified as an important prognostic factor in Hodgkin's disease (HD) in adults. Information regarding the impact of histology on outcome in childhood HD is scarce. This study determines the effect of histology on the overall survival (OS) or progression-free survival (PFS) in a national series of children treated in a standardized manner. PATIENTS AND METHODS: The results of treatment of 331 assessable patients, treated between January 1, 1982 and June 30, 1992, in the United Kingdom Children's Cancer Study Group (UKCCSG) Hodgkin's study I were reviewed to evaluate OS, PFS, and deaths according to stage and histology. Treatment was either involved-field radiation alone (stage IA) or chlorambucil, vinblastine, procarbazine, and prednisolone (ChlVPP) chemotherapy with or without mediastinal radiation. All were clinically staged at diagnosis. RESULTS: Nodular sclerosing (NS) HD was the most common histologic subtype (155 of 331 patients [47%]) and was uniformly distributed through all stages. Lymphocyte-depletion (LD) HD was extremely uncommon (< 1%). Mixed-cellularity (MC) HD had the highest relapse rate, but this was only significant (P < .05) in stage I patients who received local irradiation alone. There was no other statistically significant difference in OS and PFS between the various histologic subtypes. Multivariate analysis for PFS and OS confirmed that stage was the most important prognostic factor and that histology did not have an effect after stratification by stage. CONCLUSION: This study demonstrates that with effective multiagent chemotherapy, histologic subtype does not influence outcome. The high relapse rates in stage I MC subtype indicates that MC HD is biologically aggressive and systemic treatment with or without local irradiation may be indicated. The high relapse rate in stage IV patients appeared to be independent of histology.  相似文献   
13.
Obesity is a major risk factor for cardiovascular disease. However, a direct link between these two states is difficult to establish, since obesity frequently occurs with other disease states such as diabetes, hypertension and atherosclerosis. Clinical studies have clearly shown that uncorrected obesity is associated with cardiac hypertrophy and compromised ventricular function. A number of rodent models of obesity have been studied in terms of cardiovascular adaptations. Cardiac function of the obese Zucker rat appears to be normal at a younger age. Only after several months is depression in cardiac function discernable. These animals are mildly hypertensive, but do not exhibit the characteristic increase in cardiac output associated with human obesity. A unique characteristic of JCR:LA-cp rat is that they develop atherosclerotic and myocardial lesions. Hearts from these animals will maintain normal function when perfused with physiological levels of calcium. At higher calcium concentrations, however, mechanical function becomes impaired. Dietary-induced obese rats exhibit many of the hemodynamic alterations associated with human obesity, but there is no evidence to-date that these animals will develop severe cardiac depression. Short-term weight reduction apparently has beneficial cardiovascular effects, but weight cycling may be harmful. Given the widespread occurrence of obesity, further studies are warranted to characterize the cardiac manifestations of this condition.  相似文献   
14.
15.
16.
17.
18.
19.
We report a case of typical chronic eosinophilic pneumonia (CEP), in a female of 27 years-old suffering bronchial asthma light. Although the initial answer to the treatment with steroids was satisfactory, the patient develop difficult to control asthma (DCA). DCA is a clinical situation which requires careful investigation of several potential factors which can be solved. We suggest a protocol of treatment for patients affected with DCA.  相似文献   
20.
BACKGROUND: X-linked severe combined immunodeficiency (SCIDXI) is an inherited immune defect which leads to death in infancy from severe infections. The defect is caused by mutations of the IL-2RG gene that encodes for the common gamma chain shared by several cytokine receptors. The disease is characterised by lack of T and NK cells with normal numbers of B cells. SCIDXI can be cured by bone marrow transplantation (BMT) or prevented by abortion after prenatal diagnosis. METHODS: A male fetus was diagnosed as having SCIDXI by molecular, immunophenotypic, and functional analyses. The fetus was injected intraperitoneally under ultrasound guidance with CD34 haematopoietic progenitor cells purified from paternal bone marrow and T-cell depleted by E rosetting. Chimerism analysis was by HLA-DQ alpha typing and gamma-chain staining on cord blood. FINDINGS: A healthy 3.6 kg boy was delivered by caesarean section at 38 weeks of gestation with no clinical or laboratory signs of graft-versus-host disease. Engraftment of donor-derived CD2 cells was found at birth. At 3.5 months of age the infant is well and his T-cell counts and function are normal. INTERPRETATION: In-utero transplantation of haematopoietic progenitor cells allowed immune reconstitution of a fetus with SCIDXI and may be an alternative to elective abortion. Our report should encourage applications of this method to other inherited disorders curable by BMT.  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