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   1457篇
  免费   10篇
  国内免费   2篇
电工技术   55篇
综合类   1篇
化学工业   303篇
金属工艺   32篇
机械仪表   21篇
建筑科学   11篇
能源动力   57篇
轻工业   117篇
水利工程   1篇
石油天然气   4篇
无线电   232篇
一般工业技术   219篇
冶金工业   260篇
原子能技术   26篇
自动化技术   130篇
  2024年   4篇
  2023年   6篇
  2022年   10篇
  2021年   27篇
  2020年   9篇
  2019年   13篇
  2018年   7篇
  2017年   13篇
  2016年   27篇
  2015年   19篇
  2014年   23篇
  2013年   56篇
  2012年   50篇
  2011年   79篇
  2010年   58篇
  2009年   70篇
  2008年   55篇
  2007年   55篇
  2006年   64篇
  2005年   48篇
  2004年   55篇
  2003年   49篇
  2002年   37篇
  2001年   31篇
  2000年   34篇
  1999年   34篇
  1998年   130篇
  1997年   75篇
  1996年   46篇
  1995年   41篇
  1994年   22篇
  1993年   30篇
  1992年   13篇
  1991年   13篇
  1990年   18篇
  1989年   13篇
  1988年   11篇
  1987年   8篇
  1986年   16篇
  1985年   15篇
  1984年   13篇
  1983年   7篇
  1982年   9篇
  1981年   9篇
  1980年   5篇
  1979年   4篇
  1977年   9篇
  1976年   13篇
  1975年   4篇
  1932年   2篇
排序方式: 共有1469条查询结果,搜索用时 15 毫秒
101.
102.
MRI was performed in 13 patients who had microwave coagulation therapy (MCT) for hepatocellular carcinoma. Six of them underwent surgery after MRI. The area (including tumor) treated by MCT showed low to high intensity on T1WI, and low to isointensity on T2WI. No enhancement was obtained on dynamic MRI. Histologically, this area was supposed to be coagulation necrosis. On T1WI, only tumor showed high intensity within the MCT area in 8 patients, and nearly uniform intensity was observed in 5 patients. Histologically, residual cell nuclei were observed in the former, and nearly uniform coagulation necrosis in the latter. The marginal part of the MCT area exhibited low intensity on T1WI, and high intensity on T2WI. Strong enhancement was obtained on dynamic MRI, and histologically, granulation tissue was noted. In the hepatic parenchyma around the MCT area, a ring-or wedge-shaped high intensity part was observed in 7 patients on T2WI, and that part was enhanced on dynamic MRI. This finding was considered to reflect changes such as hepatic hyperperfusion. In terms of the capability of visualizing residual tumor after MCT, MRI was superior to CT. Furthermore, a clear distinction was seen between the MCT area and non-MCT area on T2WI and dynamic MRI. Thus, MRI was useful in the determination of additional therapy.  相似文献   
103.
It has been ascertained whether or not the model capable of predicting the stress-strain relation of plain carbon steels, previously proposed, is applicable to the estimation of mill loads in the finishing process (consisting of six mill stands) of a hot strip mill. An appreciably good agreement with the predicted and measured mill load values has been obtained in the earlier passes where the strip microstructure is regarded to have completed static recrystallization, and the predicted mill loads in the later passes have been far less than the measured load owing to the effect of the strain accumulated in the previous rolling process. Then, a simple model to predict the accumulated strain has been constructed and introduced into the calculation of mill loads. As a result, the predicted mill loads have been fairly improved over the whole passes in the finishing process.  相似文献   
104.
Type I diabetes susceptibility genes have been identified within the major histocompatibility complex (MHC) on chromosome 6p21.3 and near the VNTR/insulin region on chromosome 11p15.5. We have used polymorphic dinucleotide repeat markers to search the human genome for additional susceptibility genes in 162 type I diabetic families with an affected sibling pair. We report that an additional susceptibility gene is located on chromosome 2q31 near HOXD8 (P < 10(-5), maximum logarithm of odds score = 4.8) in an analysis of affected sibling pairs having specific human leukocyte antigen (HLA) and hypervariable nucleotide tandem repeat (VNTR)/insulin gene haplotypes (absence of high-risk HLA-DR3/4 haplotypes and presence of homozygous high-risk class I VNTR alleles). These results suggest the interaction of a minimum of three genes in the pathogenesis of type I diabetes in humans.  相似文献   
105.
Low-temperature (290°C) area-selective regrowth by molecular layer epitaxy (MLE) was applied for the fabrication of an ultra-shallow sidewall (50 nm) GaAs tunnel junction. Fabricated tunnel junctions have shown a record peak current density up to 35,000 A/cm2. It is shown that the tunnel junction characteristics are strongly dependent on the sidewall orientation and the AsH3 surface treatment conditions just prior to regrowth. The effects of AsH3 surface treatment are discussed in view of the control of surface stoichiometry.  相似文献   
106.
This quad-issue processor achieves 1-GHz operation through improved dynamic circuit techniques in critical paths and a more extensive on-chip memory system which scales in both bandwidth and latency. Critical logic paths use domino, delayed clocked domino, and logic embedded in dynamic flip-flops for minimum delay. A 64-KB sum-addressed memory data cache combines the address offset add with the cache decode, allowing the average memory latency to scale by more than the clock ratio. Memory bandwidth is improved by using wave pipelined SRAM designs for on-chip caches and a write cache for store traffic. Memory power is controlled without increased latency by use of delayed-reset logic decoders. The chip operates at 1000 MHz and dissipates less than 80 W from a 1.6-V supply. It contains 23 million transistors (12 million in RAM cells) on a 244 mm2 die  相似文献   
107.
108.
Flow and deformation of fresh concrete   总被引:1,自引:0,他引:1  
The results of studies made from the standpoint of rheology on methods of predicting flows and deformations of fresh concrete and mortar as basic research for rationalization of concrete construction are described. This paper contains as follows:
  1. method of measuring viscosity of fresh concrete and mortar;
  2. method of estimating deformation of fresh concrete due to its own weight;
  3. proposal of the “Inclined Pipe Test Method” as a new method of testing consistency of grout mortar.
  相似文献   
109.
The effect of nine transition elements on the morphology, distribution and composition of MC carbides (MCs) in a nickel-base superalloy, IN-100, was investigated by differential thermal analysis (DTA), microstructural observation and X-ray microanalysis. The doping with tantalum, tungsten and molybdenum caused a significant change in the morphology and distribution of MCs as well as the profile of DTA curve of IN-100. The compositions of the MC in IN-100 were TiC and (Ti0.80Mo0.17V0.03) C, and the doping with niobium, tantalum and tungsten changed significantly the composition of MC. On the other hand, the doping with chromium, vanadium, hafnium and zirconium scarcely changed the composition. In addition to TiC and (Ti, Mo, V) C, zirconium- and hafnium-rich MCs were found in the zirconium- and hafnium-doped alloys, respectively. The effect of the dopants on the composition of MCs could be explained by a relationship between the metallic radius and the free energy of formation for the MC.  相似文献   
110.
Ohara H  Konno H  Sasaki M  Suzuki M  Murata K 《Applied optics》1996,35(22):4476-4480
The 360° profilometry of a three-dimensional (3-D) diffuse object by use of the light intersection and its image reconstruction by surface shading are presented. The lack of data in one direction, which was due to occlusion, was compensated by the projection of two lines of light from different directions. Some experiments to profile objects and their reconstruction by computer are shown. The entire surface model was constructed, and a real shading image was obtained by means of computer graphics.  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