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   348篇
  免费   3篇
电工技术   8篇
化学工业   85篇
金属工艺   6篇
机械仪表   5篇
能源动力   13篇
轻工业   13篇
石油天然气   1篇
无线电   20篇
一般工业技术   51篇
冶金工业   106篇
原子能技术   18篇
自动化技术   25篇
  2022年   6篇
  2021年   9篇
  2020年   2篇
  2019年   1篇
  2018年   6篇
  2017年   3篇
  2016年   6篇
  2015年   4篇
  2014年   13篇
  2013年   13篇
  2012年   11篇
  2011年   20篇
  2010年   10篇
  2009年   15篇
  2008年   15篇
  2007年   14篇
  2006年   11篇
  2005年   7篇
  2004年   8篇
  2003年   7篇
  2002年   10篇
  2001年   3篇
  2000年   4篇
  1999年   5篇
  1998年   23篇
  1997年   26篇
  1996年   25篇
  1995年   15篇
  1994年   11篇
  1993年   12篇
  1992年   2篇
  1991年   4篇
  1989年   1篇
  1988年   2篇
  1987年   5篇
  1986年   3篇
  1985年   2篇
  1984年   9篇
  1982年   1篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1970年   1篇
排序方式: 共有351条查询结果,搜索用时 15 毫秒
111.
112.
Several plasma components, such as complement (C) components, play a role in the clearance of liposomes from the circulation. The interactions between liposomes and the C system were investigated in this study. Multilamellar vesicle (MLV) liposomes, which were damaged by activation of the complement, became susceptible depending on the density of cetylmannoside (Man) on the liposome membrane, and activation proceeded through the alternative C pathway as observed for liposomes without Man (PC-MLV) (K. Funato et al., Biochim. Biophys. Acta 1103:198-204, 1992). In addition, the capacity of Man-modified liposomes (Man-MLV) to activate the alternative C pathway was abolished by preadsorption of plasma with Man-MLV but not with PC-MLV. The results suggest that a specific plasma factor adsorbed with Man-MLV was responsible for the augmentation of the C activation and, further, that the rapid clearance of Man-MLV from the circulation is caused by both enhanced C-mediated liposome permeability and enhanced C-mediated phagocytosis of liposomes.  相似文献   
113.
We described our experiences with intraoperative spinal cord monitoring in 6 cases of spinal cord tumor. During the operation, spinal cord evoked potential following unilateral spinal cord stimulation was recorded from subdural monitoring electrodes. This series included two cases of intradural extramedullary tumor (one case each of neurinoma and of meningioma) and four cases of intramedullary tumor (2 cases of cavernous angioma, one case each of ependymoma, and of glioblastoma multiforme). Before the removal of the tumor, the spinal cord evoked potential showed lower amplitude or no response on the more affected side in all 6 cases. During the operation, the different intraoperative changes were shown on each side. The authors think that the detection of unilateral damage to the spinal cord is possible in spinal cord evoked potential using unilateral spinal cord stimulation.  相似文献   
114.
Phosphotetradecavanadate (PV14) was dispersed on a silica gel chemically modified with a silane coupling agent (AnPS-SiO2) by an equilibrium adsorption method. The PV14 contents approximately correlated with the V(IV) spin contents by ESR. PV14 dispersed on AnPS-SiO2 resulted in a quite high selectivity for formaldehyde such as 97% in methanol oxidation.  相似文献   
115.
The Gaussian Thermal Flux model is a fast thermal radiation sub-model which operates with minimal input and predicts flux on sloped surfaces for both clear and cloudy days. This paper presents the model's theoretical basis. It is distinguished from empirical models by its detailed two dimensional treatment of clouds, its computation of air layer transmissivity above and below cloud layers and its consideration of cloud height effects. The model improves upon existing flux emissivity and multi-band or line models by being independent of soundings and by its use of gaussian quadrature to speed the numerical integrations. It may be input entirely from standard screen level meteorological measurements.  相似文献   
116.
117.
In Okinawa, a subtropical island in southern Japan, squamous cell carcinoma (SCC), especially the well-differentiated form, is prevalent, while this form is relatively rare in both the mainland and other countries (e.g. United States of America). More patients with SCC from Okinawa, moreover, were positive for human papillomavirus (HPV) DNA by polymerase chain reaction (PCR) (79%), and harbored HPV types 6, 16 and 18, in combination. On the other hand, less than 30% of the mainland patients were positive for HPV DNA by PCR. Those patients who were positive all harbored only one HPV type. Furthermore, in Okinawa, there were a significant number of cases with adenosquamous carcinoma, and they too were positive for HPV DNA. The SCC and the adenocarcinoma cells adjacent to the SCC component in these cases were also positive for HPV DNA, and such adenocarcinoma cells were enlarged in size with relatively wide cytoplasm. The authors postulate that HPV infects adenocarcinoma cells and changes them to enlarged cells, followed by squamous metaplasia. In this report, HPV DNA was transfected to adenocarcinoma cells (cultured cell lines) and this showed that HPV causes squamous metaplasia. In addition, aberrant expression of p53 was demonstrated in a large number of the SCC cases in Okinawa. The enlarged adenocarcinoma cells adjacent to the SCC components in adenosquamous carcinomas also showed aberrant expression of p53. The recent advances in the studies of anti-oncogenes, p53, etc. and oncogenes are outlined. It is to be noted that the molecular mechanisms of carcinogenesis in the lung have been studied in general, classifying lung tumors into two groups, namely, small cell carcinoma (SCLC) and non-small cell carcinoma (NSCLC). However, because human lung cancer is represented by a wide variety of histologic types, molecular genetic studies according to a more detailed histological subclassification is needed.  相似文献   
118.
A carrot gene homologous to the ABI3 gene of Arabidopsis was isolated from a carrot somatic embryo cDNA library and designated C-ABI3. The sequence of C-ABI3 was very similar to those of ABI3 of Arabidopsis and VP1 of maize in certain conserved regions. The expression of C-ABI3 was detected specifically in embryogenic cells, somatic embryos and developing seeds. Thus, expression of C-ABI3 was limited to tissues that acquired desiccation tolerance in response to endogenous or exogenous abscisic acid (ABA). Endogenous levels of ABA in seeds increased transiently and then desiccation of seeds started. The expression of C-ABI3 in developing seeds was observed prior to the increase in levels of endogenous ABA that was followed by desiccation of seeds. In transgenic mature leaves in which C-ABI3 was ectopically expressed, expression of ECP31, ECP63 and ECP40 was induced by treatment with ABA, which indicates that the expression of ECP genes was controlled by the pathway(s) that involved C-ABI3 and ABA. This suggests that C-ABI3 has the same function as VP1/ABI3 factor in carrot somatic embryos.  相似文献   
119.
A position sensitive detector system composed of a channel plate, a vidicon TV camera, and a computer is utilized for multichannel detection of ESCA spectra. It is demonstrated that the system achieves a marked improvement of measurement speed, S/N ratio, and sensitivity. The system also realized an improvement of spatial resolution while retaining energy resolution.  相似文献   
120.
Spherical mesoporous SiO2 and SiO2–TiO2 particles were synthesized by sol–gel method using W/O emulsion under microwave irradiation. In SiO2 system, W/O emulsion was prepared by mixing partially hydrolyzed Si(OC2H5)4 aqueous solution including C18TAC as template with n-hexane solution including polyglycerol polyricinalate as emulsifier. In SiO2–TiO2 system, Ti(OC2H5)4 capped by acetylacetone was added to the aqueous phase. In both cases, spherical products were synthesized by heating of W/O emulsion for 30 min under microwave irradiation. The specific surface area and pore size of spherical products were 800 m2/g and 1.6 nm, respectively, which indicates that the spherical products are mesoporous. These results suggest that sol–gel reaction in water phase proceeds rapidly because microwave quickly and selectively heats up the aqueous solution.  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