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   83342篇
  免费   3707篇
  国内免费   256篇
电工技术   940篇
综合类   734篇
化学工业   13072篇
金属工艺   1417篇
机械仪表   1828篇
建筑科学   2181篇
矿业工程   503篇
能源动力   1383篇
轻工业   8853篇
水利工程   981篇
石油天然气   245篇
武器工业   9篇
无线电   3841篇
一般工业技术   10385篇
冶金工业   28951篇
原子能技术   377篇
自动化技术   11605篇
  2023年   593篇
  2022年   638篇
  2021年   1277篇
  2020年   990篇
  2019年   1157篇
  2018年   2159篇
  2017年   2328篇
  2016年   2751篇
  2015年   2061篇
  2014年   2057篇
  2013年   3680篇
  2012年   4483篇
  2011年   4860篇
  2010年   2564篇
  2009年   2571篇
  2008年   2320篇
  2007年   2201篇
  2006年   1704篇
  2005年   4194篇
  2004年   3338篇
  2003年   2822篇
  2002年   1652篇
  2001年   1349篇
  2000年   786篇
  1999年   1132篇
  1998年   8334篇
  1997年   5287篇
  1996年   3483篇
  1995年   2102篇
  1994年   1553篇
  1993年   1657篇
  1992年   490篇
  1991年   534篇
  1990年   483篇
  1989年   460篇
  1988年   478篇
  1987年   377篇
  1986年   340篇
  1985年   339篇
  1984年   209篇
  1983年   192篇
  1982年   280篇
  1981年   333篇
  1980年   356篇
  1979年   155篇
  1978年   176篇
  1977年   894篇
  1976年   1911篇
  1975年   160篇
  1973年   130篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
941.
Hemostasis of 100 patients with severe diphtheria infection was studied throughout the disease. The patients were found to have marked procoagulant, anticoagulant and fibrinolytic disorders. Antithrombogenic activity of the vascular wall was also abnormal. The above impairments correlated with the symptoms severity and are interpreted as DIC syndrome which ran subclinically or as hemorrhagic syndrome. The majority of the patients underwent a hyperhypocoagulant phase of DIC syndrome.  相似文献   
942.
943.
We have performed immunohistochemical staining for p53 and c-erbB-2 on formaldehyde-fixed, paraffin-embedded primary invasive ductal carcinomas from 112 patients, with a minimal follow-up time of 60 months. All of them had received postoperative chemoradiation therapy. We have analyzed the association of these factors with epidemiologic risk factors, histopathologic features and hormonal receptor status and the influence on prognosis. Our results indicate that the expression of c-erbB-2 protein defines a group of node-negative patients with poor prognosis. The overexpression of c-erbB-2 has shown a significant association with estrogen receptor status (those tumors expressing c-erbB-2 are usually estrogen receptor negative), presence of fibrosis and lymphoplasmacytoid infiltrates. P53 expression has shown no relation either with prognosis or with any other histopathologic or clinical feature. The only factors with prognostic influence in our series have been tumor size, the presence of node metastases, TNM stage and the prognostic morphometric index (Baak's index), apart from c-erbB-2 in node-negative patients. However, only the TNM stage showed an independent association with prognosis after a multivariate analysis. In summary, in our experience the expression of p53 protein has no prognostic influence on breast carcinoma, and TNM stage remains to be as the most powerful prognostic factor in these patients.  相似文献   
944.
One hundred and eighty-one consecutive patients with standard-risk leukaemia were transplanted with HLA-identical sibling grafts depleted of lymphocytes using counter-flow centrifugation. In 116 patients, standard conditioning was intensified by the addition of anthracyclines. Multivariate analysis revealed significantly more acute GVHD > or = grade 2 and a trend towards more chronic GVHD in patients conditioned with the addition of anthracyclines. For all patients the risk for chronic GVHD, but not for acute GVHD increased with a higher number of T cells in the graft. The projected 5-year probability of relapse was significantly lower in the group of patients conditioned with anthracyclines; 26% versus 52% (P = 0.015). In multivariate analysis the addition of anthracyclines to the conditioning regimen was the only significant factor contributing to a lower probability of relapse. The projected 5-year probability of leukaemia-free survival [LFS] in the patients conditioned with and without the addition of anthracyclines was 56% and 36%, respectively (P = 0.004). In multivariate analysis the addition of anthracyclines to the conditioning regimen correlated significantly with a lower number of mixed chimaeras in patients at 6 and 12 months after BMT. Mixed chimaerism at 6 months after transplantation did not significantly correlate with a higher incidence of relapse in further follow-up. In contrast, mixed chimaerism at 12 months after BMT was significantly associated with higher relapse rate. We conclude that the addition of anthracyclines to the conditioning regimen improves outcome of BMT using T-cell-depleted grafts.  相似文献   
945.
946.
The last decades of the twentieth century are witness of increased interest in the study of scientific heritage in the Islamic world. The already established opinion of Islamic science as only intermediary between classical Greece and Latin West is seriously challenged. The reason for this are original sources from which the historians of our century have extracted solid evidence of high level of originality achieved by Muslim scientists in the past. Through their work in Bagdad, Buhara, Samarkand, Reyy, Kairo, Maraga, Damascus, Kordova they have shown that Islamic sciences including medicine had theoretical and practical answers to the problems characteristic of their times. Throughout its History Bosnia and Herzegovina itself has been exposed to various cultural influences from the West as well as from the Islamic East. When we try to study the history of medicine and health profession generally, we have to take into account the early Arabic sources of which short survey is given in this paper. With this in mind, one can make one preliminary conclusion at least; Islamic medicine has reached respectable level of practical and theoretical achievements while the volume of books and number of people engaged in its practice produced series of biographies and bibliographies as clear proof of its growth and level it has attained.  相似文献   
947.
948.
In Slovakia, similarly as in the Czech Republic, marked changes in the pharmaceutical services have gradually been taking place since 1990. Principal legal and organizational changes have been connected also with the extent and standard of provided pharmaceutical services. The present paper reports the results of a questionnaire research regarding the evaluation of the standard of pharmaceutical services in the year 1995 where there existed both state-owned and private public pharmacies. The questionnaire research was carried out in 20 pharmacies of the Region of West Slovakia, 407 questionnaires were evaluated. The questionnaires were evaluated from the viewpoint of sociological classification of respondents (economically active persons, old-age pensioners) as well as the sex of pharmacy customers. The results confirmed relatively little significant differences between the satisfaction with pharmaceutical services either according to the sex or the social position of the respondents. A relatively significant proportion of the respondents have expressed critical views about the participation of the patient in covering the costs of drugs and slow execution of order of drugs.  相似文献   
949.
The efficacy of continuous methods of renal substitute therapy (RST) in patients with multiple organ failure is assessed. The patients were divided in 2 groups administered different types of PST. Group 1 were 16 patients subjected to RST by peritoneal dialysis, in group 2 (n = 16) GP and/or GDP were used. Hemodynamics, hematological and biochemical values, and clearance of inflammation mediators were monitored and hemohydrobalance and complications of therapy assessed in the course of RST. Both RST methods proved to be highly effective. The possibility of differentiated use of peritoneal dialysis and GP/GDP permits an individual approach to treatment, and equally high efficacy of both methods solves the problem of treating total renal insufficiency in the majority of patients with multiple organ failure following cardiovascular surgery.  相似文献   
950.
The antiphlogistic Ibuprofen incorporated in liposomes caused a decrease of the inflammatory edema induced by Carrageenan in the distal part of the rat's hind leg after both the intramuscular and percutaneous administration. The antiphlogistic effect of free Ibuprofen in the cream was weaker. Intramuscular administration of empty liposomes slowed down in the initial stages the development of inflammation and slightly diminished the size of edema.  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