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   1029篇
  免费   13篇
  国内免费   2篇
电工技术   61篇
综合类   2篇
化学工业   246篇
金属工艺   25篇
机械仪表   21篇
建筑科学   30篇
矿业工程   1篇
能源动力   51篇
轻工业   56篇
水利工程   1篇
无线电   70篇
一般工业技术   172篇
冶金工业   207篇
原子能技术   27篇
自动化技术   74篇
  2023年   4篇
  2022年   14篇
  2021年   19篇
  2020年   7篇
  2019年   11篇
  2018年   7篇
  2017年   11篇
  2016年   13篇
  2015年   11篇
  2014年   23篇
  2013年   36篇
  2012年   27篇
  2011年   50篇
  2010年   37篇
  2009年   45篇
  2008年   55篇
  2007年   24篇
  2006年   36篇
  2005年   32篇
  2004年   28篇
  2003年   42篇
  2002年   33篇
  2001年   33篇
  2000年   22篇
  1999年   27篇
  1998年   88篇
  1997年   52篇
  1996年   44篇
  1995年   30篇
  1994年   20篇
  1993年   36篇
  1992年   15篇
  1991年   7篇
  1990年   12篇
  1989年   11篇
  1988年   4篇
  1987年   8篇
  1986年   3篇
  1985年   4篇
  1984年   15篇
  1983年   6篇
  1982年   3篇
  1981年   5篇
  1980年   3篇
  1978年   4篇
  1977年   3篇
  1976年   8篇
  1974年   3篇
  1973年   4篇
  1972年   3篇
排序方式: 共有1044条查询结果,搜索用时 15 毫秒
991.
The patient was a 68-year-old male, who underwent total gastrectomy for giant leiomyosarcoma of the stomach and then had multiple hepatic metastases one year and six months later. Thus, transarterial hepatic chemo-embolization therapy with Lipiodol, adriamycin and gelfoam was given. Moreover, using a reservoir catheter and infusion arterial port, intermittent arterial infusion therapy with adriamycin, cyclophosphamide, and vincristine was attempted. In the metastasis lesion where there were rich blood vessels, Lipiodol was accumulated and the tumor was reduced on abdominal CT. The result indicated the efficacy of this treatment.  相似文献   
992.
The Resonant Frequency (RF) of the tibia is proportional to its stiffness. As a fractured tibia heals, its RF should increase. The RF was serially determined in 74 fractured tibias (205 examinations). These were subdivided by fracture location and fixation. Fast Fourier transform software generates the RF from data obtained with an instrumented impactor and accelerometer. The RF was normalized by expressing it as a ratio of the intact tibia. This ratio is called the tibial stiffness index (TSI). A 20 point tibial fracture score (TFS) quantitated the clinical and radiographic signs of healing. For each group the paired TSI and TFS were compared by regression analysis. Except for those fractures limited to the proximal fourth of the tibia, the TSI was found to correlate significantly (p = 0.0001) with the TFS. Fractures without fixation and those with unlocked, unreamed tibial nails showed very significant correlation of TSI with TFS (p = 0.0001). RF analysis was not useful in fractures with locked or reamed tibial nails. Examination of tibia with external fixation showed significant correlation (p = 0.02) of the TSI with the TFS.  相似文献   
993.
994.
OBJECTIVES: To examine an association between specific IgE to methyltetrahydrophthalic anhydride (MTHPA) and exposure time, atopic history, smoking habits, and total IgE concentrations. METHODS: A cross sectional survey was carried out on a population of 148 workers from two condenser plants using epoxy resin with MTHPA, an acid anhydride curing agent known to cause allergy. RESULTS: Using a Pharmacia CAP system with a MTHPA human serum albumin conjugate, specific IgE antibody was detected in serum from 97 (66%) out of the 148 workers exposed to MTHPA. Stepwise multiple linear regression analysis showed a striking relation between log concentrations of specific and total IgE (P < 0.0001). Furthermore, when the workers were divided into two groups according to a cut-off point (100 IU/ml) between low and high total IgE, current smoking was significantly (P = 0.025) associated with specific IgE production only in the group with low total IgE (< 100 IU/ml). CONCLUSIONS: Smoking is the most significant risk factor for raising specific IgE to MTHPA in the group with low total IgE concentrations.  相似文献   
995.
996.
OBJECTIVE: Our objectives were to study delayed xenograft rejection and the effectiveness of pretransplantation total lymphoid irradiation combined with immunosuppression on rejection in a pig-to-baboon cardiac xenograft model. METHODS: Baboons were treated with pretransplantation total lymphoid irradiation, cyclosporine A (INN: ciclosporin), and methotrexate. Orthotopic pig-to-baboon cardiac transplantations were performed after depletion of circulating xenoreactive natural antibody by pretransplantation donor organ hemoperfusion. Tissue samples were collected for immunologic and immunopathologic evaluation. RESULTS: Pig cardiac xenografts survived more than 18 and 19 days without evidence of hyperacute rejection. Immunologic analysis of serum samples demonstrated that circulating xenoreactive natural antibody levels did not return to pretransplantation levels. The production of xenoreactive natural antibodies from the recipient's splenocytes was inhibited completely. Histologic examination of xenografts showed the feature of acute vascular rejection. Immunohistochemical studies demonstrated infiltration of cardiac xenografts by large numbers of macrophages, small numbers of natural killer cells, and a few T cells. The infiltrating macrophages also showed expression of interleukin-1 and tumor necrosis factor. Diffuse deposition of immunoglobulin G, C1Q, C3, and fibrin on xenograft vasculature was observed. Interleukin-2 expression was not found in rejected cardiac xenografts. Xenograft endothelial cells also showed evidence of activation (expression of cytokines interleukin-1 and tumor necrosis factor). CONCLUSIONS: This study demonstrates prolonged discordant cardiac xenograft survival and delayed xenograft rejection in a pig-to-baboon model. The delayed xenograft rejection is mediated by both humoral and cellular mechanisms. Pretransplantation total lymphoid irradiation combined with cyclosporine A and methotrexate can inhibit xenoreactive natural antibody production but not elicited antipig antibody production and the xenoreactivity of macrophages.  相似文献   
997.
In this paper, an attempt is made to develop a decision-making supporting system for the aesthetic design of dam structures. The present system is based on genetic algorithm and computer graphics. Genetic algorithm is able to produce many design alternatives, whereas computer graphics is useful to prepare their view simulations. In order to evaluate the alternatives, the analytical hierarchy process method is used to reflect the preference of designers. A numerical example of coloring a dam structure is presented to demonstrate the applicability of the system developed here.  相似文献   
998.
999.
1000.
A charge pumping method is proposed for the direct measurement of the hot-carrier-induced fixed charge near the drain junction of p-MOSFETs. By holding the rising and falling slopes of the gate pulse constant and then varying the highest and lowest levels, the local threshold and local flatband voltages are readily obtained. The spatial distribution of fixed charges is directly calculated from the changes that occur in these curves after the application of stress. This method is quite simple and, specifically, requires no information about impurity concentrations in the substrate. The validity and reliability of the method have been supported by computer simulations  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