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   333篇
  免费   16篇
  国内免费   7篇
电工技术   5篇
综合类   1篇
化学工业   43篇
金属工艺   8篇
机械仪表   7篇
建筑科学   22篇
矿业工程   1篇
能源动力   6篇
轻工业   79篇
水利工程   4篇
石油天然气   1篇
无线电   31篇
一般工业技术   48篇
冶金工业   29篇
原子能技术   11篇
自动化技术   60篇
  2023年   1篇
  2022年   3篇
  2021年   6篇
  2020年   1篇
  2019年   8篇
  2018年   11篇
  2017年   4篇
  2016年   11篇
  2015年   8篇
  2014年   20篇
  2013年   24篇
  2012年   14篇
  2011年   26篇
  2010年   19篇
  2009年   22篇
  2008年   23篇
  2007年   14篇
  2006年   17篇
  2005年   8篇
  2004年   14篇
  2003年   14篇
  2002年   11篇
  2001年   4篇
  2000年   5篇
  1999年   6篇
  1998年   6篇
  1997年   7篇
  1996年   6篇
  1995年   3篇
  1994年   7篇
  1993年   6篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   6篇
  1983年   2篇
  1982年   1篇
  1981年   3篇
  1979年   2篇
  1978年   2篇
  1976年   1篇
  1970年   1篇
排序方式: 共有356条查询结果,搜索用时 15 毫秒
21.
Abstract

In 2010, the Finnish Ministry of the Environment launched a re-evaluation and revision of the 1993 inventory of Nationally Valuable Landscape Areas (NVLAs). While the inventory works for implementation of the National Land Use Guidelines, it also showcases the use of landscapes in Finnish national heritage policy. Based on critical readings of three influential Finnish administrative landscape policy reports, I claim that NVLAs, as tools of heritage policy, are based on the approaches and methodologies that have supported Finland’s development into a modern nation state by providing tools for intellectual governance of the national past and territory. Rather than meeting the diversity of landscape conceptions, as defined in the European Landscape Convention, the NVLAs run a risk of being in conflict with citizens and actors that do not share the administrative assumption of landscapes as public containers of national heritage.  相似文献   
22.
It was hypothesized that human mesenchymal stromal cell (hMSC) can be guided by patterned and plain amorphous diamond (AD), titanium (Ti), tantalum (Ta) and chromium (Cr) coatings, produced on silicon wafer using physical vapour deposition and photolithography. At 7.5 h hMSCs density was 3.0–3.5× higher (P < 0.0003, except Ti) and cells were smaller (68 vs. 102 μm, P 0.000006–0.02) on patterns than on silicon background. HMSC-covered surface of the background silicon was lower on Ti than AD patterns (P = 0.015), but at 5 days this had reversed (P = 0.006). At 7.5 h focal vinculin adhesions and actin cytoskeleton were outgoing from pattern edges so cells assumed geometric square shapes. Patterns allowed induced osteogenesis, but less effectively than plain surfaces, except for AD, which could be used to avoid osseointegration. All these biomaterial patterns exert direct early, intermediate and late guidance on hMSCs and osteogenic differentiation, but indirect interactions exist with cells on silicon background.  相似文献   
23.
The aim of the study was to screen any possible synergistic effect available with combination of plant oils and boron compounds to decrease boron leaching and improve thermal degradation of wood by means of dual treatment. In order to reduce the leachability of boron compounds, sapwood of beech and Scots pine samples were treated with oils to create a hydrophobic layer on the wood cells that may prevent water uptake. Increase (%) of boron retained in double-treated samples after leaching was approximately 20% compared to boron-treated samples without oil. The most promising results on boron leaching obtained in the case of using waste and sunflower oil. Thermogravimetric residues were increased by the higher loading of boron compounds in double-treated samples. Spectra of FTIR-Photoacoustic spectrometer showed some deformation of lignin and cellulose followed by degradation of hemicelluloses of treated wood samples due to heat effect at 160 °C.  相似文献   
24.
OBJECTIVES: Reactive joint complications triggered by salmonella gastroenteritis are increasingly reported, but the outcome and long term prognosis of the patients is incompletely known. This study looked at the prognosis of salmonella arthritis in patients hospitalised in 1970-1986. METHODS: Hospital records from two hospitals in southern Finland were screened for patients with the discharge diagnosis of salmonellosis or reactive, postinfectious arthritis or Reiter's disease. For the patients with confirmed diagnosis of reactive salmonella arthritis, data about the acute disease were collected from the hospital records. A follow up study was performed. RESULTS: There were 63 patients (28 women, 35 men, mean age 36.5 years) with salmonella arthritis. Urethritis occurred in 27%, eye inflammation in 13%, and low back pain in 44% of the patients. HLA-B27 was present in 88%. More men than women were HLA-B27 positive. HLA-B27 positive patients had higher erythrocyte sedimentation rate (mean 80.9 v 46.5 mm 1st h, p = 0.0180). Also, extra-articular features and radiological sacroiliitis were seen only in HLA-B27 positive patients. A follow up study was performed on 50 patients mean 11.0 (range 5-22 years) later. Twenty patients had recovered completely. Ten patients had mild joint symptoms, 11 patients had had a new acute transient arthritis, and five acute iritis. Eight patients had developed chronic spondyloarthropathy. Radiological sacroiliitis was seen in six of 44 patients, more frequently in male than in female patients (32% v 0%; p = 0.0289). Recurrent or chronic arthritis, iritis or radiological sacroiliitis developed only in HLA-B27 positive patients. CONCLUSION: Joint symptoms are common after reactive salmonella arthritis. HLA-B27 contributes to the severity of acute disease and to the late prognosis.  相似文献   
25.
26.
27.
Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90Sr β-source. The n-side has been studied using a laser.  相似文献   
28.
Samples of a low alloy steel piping material taken from the full scale corrosion fatigue test loop of the Heissdampfreaktor (HDR) plant have been tested at 240°C in high oxygen reactor water. The small-scale specimens (CT25) were exposed to a similar loading spectrum to that which has been used in the full-scale corrosion fatigue tests at the HDR-plant. During the autoclave tests cyclic crack growth rates were determined. Fracture surface investigations were performed not only for the laboratory test specimens but also for the fracture surface of a sample taken from the HDR test loop piping after the full scale test. In this paper the autoclave testing results and fracture surface observations are presented and compared to those obtained in the HDR piping tests.  相似文献   
29.
This paper presents a theoretical overview and analysis of clock jitter in a switched capacitor (SC) Sigma-Delta (ΣΔ) Analog-to-Digital Converter (ADC). We start by defining three different types of jitter effects and proceed to analyze their impact, both mathematically and by simulations. The main jitter assumption throughout this analysis is that it is stochastic white Gaussian noise. Using this assumption, the ΣΔ performance is characterized in terms of Signal-to-Jitter-Noise-Ratio (SJNR) for each jitter effect. Non-uniform sampling effects have, to some extent, been characterized in litterature (S.R. Norsworthy, R. Schreier and G.C. Temes, Delta-Sigma Data ConvertersTheory, Design and Simulation, IEEE Press, New Jersey, 1997). However, varying phase-length effects are also a main focus in this work since they can have a significant impact on the total ADC performance depending on settling accuracy and characteristic. Furthermore, because SC circuits usually operate on a two-phase clock, jitter may give rise to a secondary effect, phase overlap, which does not appear when dealing with a single-phase clock. This effect severely degrades the resolution of a ΣΔ and therefore a thorough understanding of the interaction of jitter on the two phases is necessary.  相似文献   
30.
The protein of distal halves of barley kernels or small meal samples was extracted with ethanolic sodium hydroxide solution. After dilution, the protein content was estimated with a spectrophotometer by measurements at 215 and 225 nm. The tryptophan content was estimated from the same extract by a spectrophotofluorimeter. The methods showed high correlations with those used for control. The presented methods can be used in screening kernels in segregating ears or selecting single plants.  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