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   276篇
  免费   0篇
电工技术   2篇
化学工业   61篇
金属工艺   1篇
机械仪表   3篇
建筑科学   24篇
能源动力   2篇
轻工业   59篇
水利工程   1篇
无线电   7篇
一般工业技术   56篇
冶金工业   28篇
自动化技术   32篇
  2023年   1篇
  2022年   6篇
  2021年   9篇
  2020年   5篇
  2019年   2篇
  2018年   1篇
  2016年   7篇
  2015年   3篇
  2014年   4篇
  2013年   10篇
  2012年   17篇
  2011年   23篇
  2010年   9篇
  2009年   16篇
  2008年   15篇
  2007年   8篇
  2006年   14篇
  2005年   16篇
  2004年   6篇
  2003年   9篇
  2002年   5篇
  2001年   7篇
  2000年   3篇
  1999年   4篇
  1998年   3篇
  1997年   6篇
  1996年   7篇
  1995年   1篇
  1994年   4篇
  1993年   6篇
  1992年   4篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1986年   4篇
  1985年   1篇
  1984年   2篇
  1983年   4篇
  1982年   4篇
  1981年   2篇
  1980年   5篇
  1979年   1篇
  1978年   1篇
  1977年   4篇
  1976年   3篇
  1974年   2篇
  1973年   2篇
  1966年   1篇
排序方式: 共有276条查询结果,搜索用时 0 毫秒
51.
Layered and homogeneous gelatin gels with controlled rheological properties were compared for their sensory characteristics, specifically sweetness, hardness, breakdown behaviour and frothing. All gels and layers had a gelatin/water concentration of 5%. The total sugar concentration was 9% in the layered samples and 0, 9, 15 or 22.5% in the homogeneous samples. These concentrations corresponded to the concentrations in the single layers.A seven-layered sample with different sugar concentrations in the layers gave a higher early sweetness intensity than a homogeneous gel with the same mean total sugar concentration. All layered gels were similar in hardness, breakdown behaviour and frothing; for the homogenous samples, sensory hardness was decreased in samples with much sugar. These gels also fell into smaller pieces than the sugarless sample. This study shows that it is possible by controlling the sugar distribution within a sample to produce sweeter gels while the sugar content is maintained.  相似文献   
52.
The passivation of copper anode in sulphuric acid industrial electrolyte at 65 °C was investigated by electrochemical noise (EN) technique using three imposed anodic currents 153, 180 and 210 mA cm−2 (galvanostatic or chronopotentiometric technique). The wavelet transforms and power spectral density (PSD) analyses have been employed to analyse the EN data. It has been found that during active dissolution the electrode surface is dominated by long time scale process and the change of the position of the maximum relative energy from D7 to D8 could be an indication of future passivation. This is associated in fast Fourier transform analyses by the disappearance of the low frequency plateau (white noise). During anodic dissolution the electrode surface was mainly undertaking general corrosion and the relative energy distribution was concentrated on large timescale crystals (D7-D8) with range of scale between 25.6 and 12.6 s. During passivation the electrode surface was dominated by short time scale process (D3), and during trans-passivation by medium (D4) followed by short time scale process (D2) with range of scale between 0.8 and 0.4 s, 1.6 and 0.8 s and 0.4 and 0.2 s, respectively. Crystals D2 and D3 could be related to metastable pitting and crystal D4 to localized corrosion.  相似文献   
53.
The ability of bacterial species to colonize and infect host organisms is critically dependent upon their capacity to adhere to cellular surfaces of the host. Adherence to cell surfaces is known to be essential for the activation and delivery of certain virulence factors, but can also directly affect host cell signaling to aid bacterial spread and survival. In this review we will discuss the recent advances in the field of bacterial adhesion, how we are beginning to unravel the effects adhesins have on host cell signaling, and how these changes aid the bacteria in terms of their survival and evasion of immune responses. Finally, we will highlight how the exploitation of bacterial adhesins may provide new therapeutic avenues for the treatment of a wide range of bacterial infections.  相似文献   
54.
This study was conducted in France within the context of waste classification (Hazardous Waste Council Directive 91/689/EEC), and focused on "ecotoxic" property (H14). In 1998, an experimental test strategy was developed to assess ecotoxicological properties of wastes using a battery of six standardized bioassays. This combined direct and indirect approaches integrating two solid-phase tests: emergence and growth inhibition of Lactuca sativa (14 days), mortality of Eisenia fetida (14 days) and four standardized tests performed on water extracts from wastes: growth inhibition of Pseudokirchneriella subcapitata (3 days), inhibition of mobility of Daphnia magna (48 h), inhibition of reproduction of Ceriodaphnia dubia (7 days), inhibition of light emission of Vibrio fischeri (30 min). This study aimed to set up preliminary conclusions on relevancy of this experimental test strategy, based on data obtained since 1998. Results were analyzed from the combined use of Hierarchical Cluster Analysis, Principal Component Analysis and Nonlinear Mapping. These multivariate analyses clearly showed that it was possible to reduce this number of tests without changing the typology of the wastes. A battery of bioassays including one solid phase test and two tests performed on water extracts (L. sativa, V. fischeri and C. dubia) was found as an optimal solution for characterizing the toxicity of the studied wastes. This optimal battery represents a good basis for determining the H14 property.  相似文献   
55.
56.
Stem cells for regenerative medicine purposes offer therapeutic benefits, but disadvantages are still ill defined. The benefit of stem cells may be attributed to their secretion of growth factors (GFs), cytokines (CKs), and extracellular vesicles (EVs), including exosomes. We present a novel cell-free stem cell-derived extract (CCM), formulated from human progenitor endothelial stem cells (hPESCs), characterized for biologically active factors using ELISA, nanoparticle tracking analysis and single particle interferometric reflectance imaging sensing. The effect on fibroblast proliferation and ability to induce stem cell migration was analyzed using Alamar Blue proliferation and Transwell migration assays, respectively. GFs including IGFBP 1, 2, 3, and 6, insulin, growth hormone, PDGF-AA, TGF-α, TGF-β1, VEGF, and the anti-inflammatory cytokine, IL-1RA were detected. Membrane enclosed particles within exosome size range and expressing exosome tetraspanins CD81 and CD9 were identified. CCM significantly increased cell proliferation and induced stem cell migration. Analysis of CCM revealed presence of GFs, CKs, and EVs, including exosomes. The presence of multiple factors including exosomes within one formulation, the ability to promote cell proliferation and induce stem cell migration may reduce inflammation and pain, and augment tissue repair.  相似文献   
57.
58.
When loss of graft function occurs more than six months after transplantation, allograft nephrectomy is not routinely performed at the time of graft failure. It is usually performed only on those patients who subsequently develop specific complications. However, little is known about the characteristics that make patients more likely to require allograft nephrectomy. The purpose of our study was to identify risk factors for the subsequent need for allograft nephrectomy in patients with graft failure occurring more than 6 months after transplantation. Forty-one patients were studied. Inclusion criteria were: loss of graft function > or = 6 months after transplantation, resumption of dialysis and initiation of weaning from immunosuppression. Thirty patients were treated with cyclosporine + prednisone +/- azathioprine and 11 with azathioprine + prednisone. Mean follow-up time was 17.8 months, ranging from 6 months to 6.1 years. Recipient age, sex and race, original renal disease, donor, donor source (cadaveric vs living related), HLA compatibility, levels of panel reactive antibodies, occurrence of initial delayed graft function, causes of graft failure and tapering of immunosuppression were similar in patients with and without allograft nephrectomy. Using univariate analysis, allograft nephrectomy was found to be significantly more frequent in patients with a history of 2 or more episodes of acute rejection than in patients with no rejection episode: 83% vs 30% (p = 0.03). In addition, allograft nephrectomy was found to be significantly more frequent if the immunosuppressive regimen included cyclosporine (62% vs 27.3%; p = 0.04). Using multivariate analysis however, the number of previous episodes of rejection was found to be the only significant predictor for allograft nephrectomy. None of the other variables considered in the multivariate analysis, including the type of immunosuppressive therapy, was identified as a significant predictor for the need to perform allograft nephrectomy. In summary, the need for late allograft nephrectomy was correlated with the number of previous episodes of acute rejection. Patients with a history of numerous rejection episodes should thus be considered more likely to require allograft nephrectomy once immunosuppression is withdrawn. Possible interventions to reduce or prevent the need for nephrectomy include more gradual tapering of immunosuppression at the time of graft failure or indefinite low-dose immunosuppressive therapy.  相似文献   
59.
Narratives are important tools in constructing an organization, and individual and collective narratives about key actors and critical events compete in defining the organization and making sense of the challenges faced in organizational change processes. This article introduces narrative interviewing and narrative analysis as qualitative methods relevant to international business research, with illustrations from a case study of a cross-border merger.  相似文献   
60.
What happens when agile methods are introduced in global outsourcing set-ups? Agile methods are designed to empower IT developers in decision-making through self-managing collocated teams. We studied how agile methods were introduced into global outsourcing from the Indian IT vendor’s perspective. We explored how agile processes in global outsourcing impacts work conditions of the Indian IT developers, and were surprised to find that agile methodologies, even after 3 years of implementation, created a stressful and inflexible work environment negatively impacting their personal lives. Many of the negative aspects of work, which agile methodologies were developed to reduce, were evident in the global agile outsourcing set-up. We propose translocality to repudiate the dichotomy of global/local reminding us that methodologies and technologies must be understood as immediately localized and situated. Translocality helps us to explain why we cannot determine the impact of global agile as a methodology independent of how it unfolds at particular sites. Instead, we must attend to concrete practices of use when evaluating the impact of new methods.  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