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   205篇
  免费   3篇
电工技术   8篇
化学工业   18篇
金属工艺   1篇
机械仪表   4篇
建筑科学   10篇
能源动力   3篇
轻工业   7篇
水利工程   3篇
无线电   42篇
一般工业技术   27篇
冶金工业   62篇
原子能技术   4篇
自动化技术   19篇
  2024年   1篇
  2022年   4篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   4篇
  2016年   9篇
  2015年   3篇
  2014年   3篇
  2013年   3篇
  2012年   2篇
  2011年   8篇
  2010年   3篇
  2009年   3篇
  2008年   8篇
  2007年   7篇
  2006年   4篇
  2005年   10篇
  2004年   3篇
  2003年   10篇
  2002年   6篇
  2001年   6篇
  2000年   7篇
  1999年   3篇
  1998年   25篇
  1997年   13篇
  1996年   8篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
  1981年   5篇
  1980年   2篇
  1978年   1篇
  1976年   3篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1971年   1篇
排序方式: 共有208条查询结果,搜索用时 0 毫秒
101.
102.
We have developed a laser‐addressed full‐color photographic quality rewritable sheet. The sheet was composed of a vertically stacked Cyan/Magenta/Yellow‐thermochromic system with a mixture of leuco dyes, developers and photothermal conversion agents in a polymer matrix. The sheet was simply manufactured by roll‐to‐roll (R2R) processes. Writing and erasing were performed by scan of near‐infrared laser light. It achieved full‐color photographic quality images with a wide color gamut with 70% coverage of the Specifications for Web Offset Publications (SWOP) standards and a high resolution of 426 ppi. Clear rewritability has also been confirmed. Non‐contact laser writing has other advantages in that it can create an image under a protection film, and it has form factor flexibility. We have developed a reliability model for high‐temperature storage and a light fastness test. This model showed a good agreement with experimental data, and the lifetime of an image was estimated to be over 8 years under ambient conditions. This technology will create applications for on‐demand rewritable image design while saving power and reducing the use of paper, which will eventually contribute to a sustainable society.  相似文献   
103.
The purpose of this study is to establish a tumor marker that can be applied for the early detection and follow-up of oral cancer patients. Employing the proteomic approach using MALDI TOF-MS, 2-DE, patient's sera and culturing cell lines, the serum autoantibodies (autoAbs) were screened and the serum levels were estimated by ELISA. Targeting the tumor cell invasion into the surrounding stromal tissues, MRC-5 human fibroblasts were employed as the target cells and a mitochondrial membrane protein, sideroflexin 3 (SFXN3), was identified. The serum anti-SFXN3-autoAb levels elevated in patients with the oral squamous cell carcinoma significantly: with 77% sensitivity and 89% specificity against control samples. The serum anti-SFXN3-autoAb levels were mildly correlated with the primary tumor sizes, however, the levels were slightly highly elevated in T1 early cancer. An immunohistochemical analysis revealed that the SFXN3 protein is expressed in the stromal fibroblasts between the caner nests and also in the basal layer of the squamous epithelium. Changes in the serum anti-SFXN3-autoAb levels after therapy correlated with the clinical tumor burden. These findings demonstrated that the serum anti-SFXN3-autoAb is worthy of clinical evaluation as a potentially of the novel tumor maker for the early detection of oral squamous cell carcinoma.  相似文献   
104.
Endothelin (ET)-1 reduced heparin-releasable lipoprotein lipase (LPL) activity in 3T3-L1 adipocytes in a concentration-dependent manner. However, a selective ETB receptor agonist, [Ala1,3,11,15]ET-1, did not act like ET-1. The ET-1-induced decrease in LPL activity was suppressed by a selective ETA receptor antagonist, BQ-123: the concentration-response curve for the ET-1 reduction of LPL activity was shifted to the right in the presence of BQ-123 in a concentration-dependent manner. This antagonistic effect of BQ-123 clarifies that the ETA receptor is responsible for the ET-1-induced reduction of LPL activity in 3T3-L1 adipocytes, which suggests that there is therapeutic potential for ETA antagonists in LPL-related lipoprotein disorders.  相似文献   
105.
Software code review, i.e., the practice of having other team members critique changes to a software system, is a well-established best practice in both open source and proprietary software domains. Prior work has shown that formal code inspections tend to improve the quality of delivered software. However, the formal code inspection process mandates strict review criteria (e.g., in-person meetings and reviewer checklists) to ensure a base level of review quality, while the modern, lightweight code reviewing process does not. Although recent work explores the modern code review process, little is known about the relationship between modern code review practices and long-term software quality. Hence, in this paper, we study the relationship between post-release defects (a popular proxy for long-term software quality) and: (1) code review coverage, i.e., the proportion of changes that have been code reviewed, (2) code review participation, i.e., the degree of reviewer involvement in the code review process, and (3) code reviewer expertise, i.e., the level of domain-specific expertise of the code reviewers. Through a case study of the Qt, VTK, and ITK projects, we find that code review coverage, participation, and expertise share a significant link with software quality. Hence, our results empirically confirm the intuition that poorly-reviewed code has a negative impact on software quality in large systems using modern reviewing tools.  相似文献   
106.
In recent years, attempts have been made to make multistage centrifugal pumps smaller in size and more efficient. However, such designs are known to cause positive-slope phenomena in the Q-H curve, especially under low-flow conditions. These phenomena, which have thus far been studied experimentally and numerically, stem from flow instability in the pump. However, their mechanisms have not yet been clarified because it depends on various parameters. In this study, we focused on diffuser rotating stall, observed in positive Q-H characteristics. This study elucidates the mechanism of positive-slope generation through experimental results and two-dimensional numerical analysis.  相似文献   
107.
When a human user interacts with an adaptive agent to achieve human-agent collaboration, active adaptation is considered to be one of the critical characteristics of the agent. In order to investigate the principal features of active adaptation, we developed a human-agent collaborative experimental environment called WAITER (waiter agent interactive training experimental restaurant) and conducted two types of experiments, a Wizard of OZ (WOZ) agent experiment and an autonomous agent experiment. The objective of these experiments is to observe how human users perceive the agents and change their instructions when interacting with adaptive agents. The results indicate that humans can recognize changes in the agent’s actions and change their instruction methods accordingly. This implies that active adaptation of the agents may encourage the adaptation of the human users and help to build an adaptation loop between them. The experimental results also suggest that active adaptation may play an important role in a human-agent collaborative task.  相似文献   
108.
Serious arsenic contamination of groundwater in Bangladesh has been frequently reported and is of great concern. In this research, repeated water sampling from the same 10 tubewells in Nawabganj municipality, Bangladesh, was conducted and analysed, focusing on the seasonal variation of water quality and the relationship among arsenic and other metals and ions. For the seasonal variation of water quality, arsenic and iron concentrations were higher in the rainy season in general although the tendency was not consistent and it depended on the tubewell and the time. Correlation between arsenic and iron could not be observed in this study (r = -0.01) when using all cases. This was because no correlation was observed in the higher arsenic concentration range. Arsenic removal by co-precipitation with coexisting iron is known as one of the locally applicable techniques in Bangladesh, but the result from this study suggests that some additional treatments such as the extra injection of iron should be performed in some cases, especially where the arsenic concentration is high. The correlation between arsenic and other substances was also analysed. As a result, manganese (r = 0.37), molybdenum (r = 0.33) and sulfate ion (r = -0.33) significantly correlated with arsenic (p < 0.05). The negative correlation between arsenic and sulfate ion implies the dissolution of arsenic into groundwater under reductive conditions although there are some exceptional cases.  相似文献   
109.
Efficient ethanol production from lignocellulosic napiergrass (Pennisetum purpureum Schumach) was examined by the combination of the simultaneous saccharification and fermentation (SSF) with commercial cellulase and Saccharomyces cerevisiae NBRC 2044 and subsequent pentose fermentation (PF) by Escherichia coli KO11. Under the optimized conditions, the combination of the SSF and PF processes resulted in the production of 144 mg g(-1) of ethanol from the non-pretreated napiergrass powder. The ethanol yield was 44.2% of the theoretical yield based on the hexose (37.5 g) and pentose (26.5 g) derived from 100 g of dry powdered napiergrass.  相似文献   
110.
SnO2 single crystals have short prismatic habits bounded by well-developed {110} and {111} faces in a pure SnO2–Cu2O flux system. When trivalent cations are added to the system, the habits drastically change to needle, acicular, or whisker forms with large aspect ratios. The addition of trivalent cations also greatly increases the nucleation rate and drastically decreases the crystal size. SEM observations and EPMA investigations reveal that the flat {111} faces transform to rounded or rough { hkl } faces by the addition of trivalent cations. This roughening transition of {111} faces, keeping {110} faces unchanged, is the cause of drastic habit modification that is attributed to the breaking of the periodic bond chain in {111} faces by impurity cations.  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