全文获取类型
收费全文 | 1187篇 |
免费 | 91篇 |
国内免费 | 42篇 |
专业分类
电工技术 | 21篇 |
综合类 | 46篇 |
化学工业 | 238篇 |
金属工艺 | 67篇 |
机械仪表 | 79篇 |
建筑科学 | 75篇 |
矿业工程 | 28篇 |
能源动力 | 59篇 |
轻工业 | 88篇 |
水利工程 | 25篇 |
石油天然气 | 29篇 |
无线电 | 158篇 |
一般工业技术 | 148篇 |
冶金工业 | 66篇 |
原子能技术 | 31篇 |
自动化技术 | 162篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 43篇 |
2021年 | 51篇 |
2020年 | 41篇 |
2019年 | 31篇 |
2018年 | 43篇 |
2017年 | 33篇 |
2016年 | 44篇 |
2015年 | 41篇 |
2014年 | 58篇 |
2013年 | 78篇 |
2012年 | 75篇 |
2011年 | 89篇 |
2010年 | 65篇 |
2009年 | 72篇 |
2008年 | 65篇 |
2007年 | 34篇 |
2006年 | 34篇 |
2005年 | 43篇 |
2004年 | 49篇 |
2003年 | 49篇 |
2002年 | 67篇 |
2001年 | 58篇 |
2000年 | 28篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有1320条查询结果,搜索用时 15 毫秒
71.
P Bang J Nygren C Carlsson-Skwirut A Thorell O Ljungqvist 《Canadian Metallurgical Quarterly》1998,83(7):2509-2515
Increased serum insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) proteolytic activity (IGFBP-3-PA) has been demonstrated in a number of clinical states of insulin resistance, including severe illness, after surgery, and in noninsulin-dependent diabetes mellitus. In the present study we assessed the role of insulin sensitivity in expression of IGFBP-3-PA in serum. In 18 patients studied, a significant increase in IGFBP-3-PA (P < 0.005) was demonstrated after colo-rectal surgery. Eight patients receiving an oral glucose load before surgery demonstrated a significant greater relative increase in IGFBP-3-PA compared with 10 patients not receiving glucose (32.9 +/- 7.1% vs. 8.6 +/- 6.7%, respectively; P < 0.05). Both groups had reduced insulin sensitivity after surgery (-58 +/- 4%; P < 0.0001; n = 18), as determined by hyperinsulinemic, normoglycemic clamps; however, the group not receiving glucose displayed 18% less insulin sensitivity than the oral glucose load group (P < 0.05). Multiple regression analysis demonstrated that the relative changes in IGFBP-3-PA and C peptide levels were inversely correlated (P < 0.05), suggesting that increased IGFBP-3-PA, presumably increasing IGF bioavailability, may be associated with decreased insulin demands. Interestingly, insulin infusion during the 4-h hyperinsulinemic, normoglycemic clamp performed 24 h after surgery (post-op) resulted in a further increase in IGFBP-3-PA in both groups (P < 0.005), whereas no significant responses could be demonstrated during the pre-op clamp. The expression of increased IGFBP-3-PA was accompanied by conversion of endogenous intact 39/42-kDa IGFBP-3 into its 30-kDa fragmented form as determined by Western immunoblotting, and this conversion was virtually complete after the 4-h post-op clamp in patients displaying marked increases in IGFBP-3-PA. Characterization of the IGFBP-3-PA demonstrated that it was specific for IGFBP-3, as no degradation of IGFBP-1 and -2 was detected, and the use of various protease inhibitors demonstrated that serine proteases and possibly matrix metalloproteinases contribute to the increased IGFBP-3-PA level after surgery. We propose that IGF bioavailability may be increased by the induction of IGFBP-3-PA in insulin-resistant subjects, and that insulin regulates IGFBP-3-PA in this state. 相似文献
72.
This paper describes a novel method for heat-up phase control of an industrial batch polymerization reactor where heat transfer characteristics change with batches due to fouling of the polymer products on the reactor wall. The main objective of the control is to settle the reactor temperature on a target value within ± 0.1°C in a minimum possible time. To achieve this goal utilizing the repetitive nature of batch operation, the control problem was defined as a tracking problem and feedback-assisted iterative learning control (FBALC) was employed as the underlying control technique. The proposed control method was applied to an industrial batch reactor polymerizing ABS resin. After on-site evaluation for an extended period of time, it was found that the proposed method gives a pronounced improvement in heat-up phase operation. Consistent heat-up profiles with a minimized settling time are obtained. 相似文献
73.
The transfer function of the model of imperfectly mixed tanks in series, involving the three parameters p, m and n, is presented. It is thus possible to evaluate easily the residence time distribution curve E(θ) and the output response for a given input. This model is compared to the axial dispersion model, through the variance of the curve for E(θ) and the average absolute error between theoretical values and experimental data. A graphical representation relates the Péclet number of the axial dispersion model to the parameters of the p, m, n model and also to the variance of the curve for E(θ). The p, m, n model gives a good approximation of experimental data; it is shown to be more versatile than the axial dispersion model. 相似文献
74.
This paper presents a decision support system, named the CLG-DSS model, which makes it possible for decision makers to assess various uncertainties in project appraisal in a systematic and explicit way. This model, a decision support system (DSS) developed within the Danish Centre for Logistics and Freight Transport (CLG) is based on cost-benefit analysis (CBA) embedded in a wider multi-criteria analysis (MCA) by the use of some principles for composite modelling assessment (COSIMA). The CLG-DSS model is set up to make use of scenario analysis (SA) and Monte Carlo simulation (MCS). A particular concern in the model is the handling of varying information across the assessment criteria and the application of SA to inform the MCS parameter setting. After the presentation of the modelling principles some ex-post case calculations for the Øresund Fixed Link are illuminating different aspects of appraisal uncertainty and thereby, at the same time, demonstrate the features of the CLG-DSS model as a useful decision support tool. It is finally concluded that appraisal of large infrastructure projects can be effectively supported by dealing with uncertainty issues in accordance with the principles described. 相似文献
75.
Dong-Hak Kim Ki-Seog Seo Ju-Chan Lee Kyoung-Sik Bang Chun-Huung Cho Sang Jin Lee Chang Yeal Baeg 《Annals of Nuclear Energy》2007
A spent fuel storage cask is required to prove the safety of its canister under a hypothetical accidental drop condition which means that the canister is assumed to be free dropped on to a pad of the storage cask during the loading of the canister into a storage cask. In this paper, finite element analyses and verifying tests for a shock-absorbing effect of a pad in a spent fuel dry storage cask were carried out to improve the structural integrity of the canister under a hypothetical accidental drop condition. The pad of the storage cask was originally designed as cylindrical steel structure filled with concrete. The pad was modified by using the structure composed of steel and polyurethane-foam instead of the quarter of the upper concrete as an impact limiter. The effects of the shape and the thickness of the steel structure and the density of the polyurethane-foam which was used in between steel structures were studied. As the optimized pad of a spent fuel dry storage cask, the quarter of the upper concrete was replaced with 12 mm thick circular steel structure and polyurethane-foam whose density was 85 kg/m3. The drop tests of a 1/3 scale model for the canister on to the original pad and the optimized pad were conducted. The effect of the pad structure was evaluated from the drop tests. The optimized pad has a greater shock-absorbing effect than the original pad. In order to verify the analysis results, strains and accelerations in the time domain by the analytical methods were compared with those by a test. The numerical method of simulating the free drop test for a dry storage cask was verified and the numerical results were found to be reliable. 相似文献
76.
The computer mouse is rarely used for drawing due to its body-fixed coordinate system, which creates a stroke that differs from the user’s original hand movement. In this study, we resolve this problem by implementing a new mouse called StereoMouse, which eliminates the rotational disturbance of the coordinate system in real-time. StereoMouse is a special mouse with two optical sensors, and its coordinate orientation at the beginning of a stroke is maintained throughout the movement by measuring and compensating for the angular deviation estimated from those sensors. The drawing performance of StereoMouse was measured by means of having users perform the task of repeatedly drawing a basic shape. The results of this experiment showed that StereoMouse eliminated the horizontal drift typically observed in a stroke drawn by a normal mouse. Consequently, StereoMouse allowed the users to draw shapes at a 10.6% faster mean speed with a 10.4% shorter travel time than a normal mouse would. Furthermore, StereoMouse showed 37.1% lower chance of making incorrect gesture input than the normal mouse. 相似文献
77.
78.
报道了 MBE外延生长的 Gax In1 - x Asy Sb1 - y四元混晶的拉曼散射谱与远红外反射谱 ,并从拉曼散射谱中观察到了 Gax In1 - x Asy Sb1 - y四元混晶的晶格振动四模行为 ;从实验中还观察到低于 180 cm- 1的若干散射峰 ,提出它们可能是与次近邻原子间相互作用的晶格振动模式有关 ;从拉曼散射谱和红外反射谱中观察到了与 Gax In1 - xAsy Sb1 - y四元混晶多声子吸收过程的有关的现象 相似文献
79.
EM Pinholt E Solheim O Talsnes TB Larsen G Bang OJ Kirkeby 《Canadian Metallurgical Quarterly》1994,33(2):193-197
The development of approaches to screening of hospital patients for harmful drinking frequently encounters resistance from both patients and hospital staff. A contributing factor could be the discomfort both feel about talking specifically about drinking. One approach to reducing this discomfort has been to mask concern about alcohol consumption into a general focus on other health and lifestyle issues. One-hundred and eighty-two patients admitted to an emergency department were presented randomly with either a straight alcohol screening questionnaire or a general health and lifestyle questionnaire with alcohol questions embedded amongst items on smoking exercise and diet. The number of returns was equal for both questionnaires which suggests the masked questionnaire does not improve the acceptability of alcohol screening in hospital environments. 相似文献
80.
J. H. Chen Y. Ren J. Seow T. Liu W. S. Bang H. G. Yuk 《Comprehensive Reviews in Food Science and Food Safety》2012,11(2):119-132
Abstract: This article reviews current and future techniques that are applied in the meat industry to ensure product safety. Consumer demand for high‐quality food and raised economic standards have triggered the development of emergent technologies to replace traditional well‐established preservation processes. Some promising nonthermal and thermal technologies, such as chemical and biological interventions, high hydrostatic pressure (HHP), irradiation, active packaging, natural antimicrobials and microwave, radiofrequency, and steam pasteurization, are under consideration for the preservation of meat products. All these alternative technologies are designed to be mild, energy‐conserving, environmentally friendly, and maintaining natural appearance and flavor, while eliminating pathogens and spoilage microorganisms. Their combination, as in the hurdle theory, may improve their effectiveness for decontamination. The objective of this article is to reflect on the possibilities and especially the limitations of the previously mentioned technologies. 相似文献