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排序方式: 共有269条查询结果,搜索用时 31 毫秒
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Heron Faggion Cristina Benincá Daniele Naviglio Fernando Augusto Pedersen Voll 《Chemical Engineering Communications》2017,204(3):406-413
A set of seven extraction experiments was performed to investigate the influence of pressure cycles on the kinetics of solute removal from leaves of mate dispersed in water. The mass ratio of liquid to dry solid (40), the temperature (32°C), and time of extraction (3600?s) were not varied. Five extraction runs were under cyclic pressurization (1?cycle?=?300?s at 91.4?kPa?+?300?s at 182.8?kPa) and stirring speeds (S) of 0, 150, 500, 1500, and 2000?rpm, while the two other ones were at constant pressure (182.8?kPa) and S close to 1500 and 2000?rpm. Based on seven pairs of parameters of a reliable second-order kinetic model (R2?≥?0.967), cyclic pressurization had no effect on equilibrium and kinetics of extraction (p?>?0.05) when the role of convection on solute transfer was negligible (S?≥?500?rpm). In the stirring speed range from 500 to 2000?rpm, the operation was controlled by diffusion (Bi >?1.7?×?103), so a transient two-dimensional diffusion model was able to describe correctly the changes of solute concentration with time. Below 500?rpm, solute transfer was governed by a combination of diffusion and convection with the external resistance to mass transfer as a function of S (16?≤?Bi?≤?28). 相似文献
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孔朝辉 《石油化工腐蚀与防护》2021,(1):22-25
在苯乙烯装置吸收塔顶的尾气中,氢气体积分数超过90%,为了更好地回收利用氢气,在尾气出装置前设置尾气增压系统进行4级压缩,每级压缩后采用水冷器降温.在大修期间检查发现,水冷器气体侧的壳体内壁局部发生严重坑蚀.分析认为,该系统的腐蚀是由二氧化碳引起的.建议对该系统进行材质升级或在水冷器的壳体液相发生腐蚀的区域衬一层厚度1... 相似文献
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Comparison of high pressure treatment and thermal pasteurization effects on the quality and shelf life of guava puree 总被引:3,自引:0,他引:3
The effects of high pressures and thermal pasteurization on the survival of microorganisms, enzyme inactivation and quality changes of guava puree during storage at 4°C were investigated and compared with untreated samples. After treatment at a pressure of 600MPa and 25°C for 15 min, the microorganisms in guava puree were inactivated to less than 10 cfu mL−1 and the product exhibited no change in colour, pectin, cloud and ascorbic acid content as compared with fresh samples. The inactivation of enzymes in guava puree by thermal pasteurization was greater than by high pressures. The microbial count in guava puree reduced to 200 cfu mL−1 and the product showed marked changes in viscosity, turbidity and colour when heated at 88–90°C for 24s. The content of pectin, cloud and ascorbic acid as well as colour in untreated and high pressurized (400MPa) guava puree gradually decreased, whereas these changes were not observed in pasteurized (88–90°C) and high pressurized (6000MPa) puree during storage at 4°C for 60 days. The guava puree treated at 600MPa and 25°C for 15 min retained good quality similar to the freshly extracted puree after storage at 4°C for 40 days. 相似文献
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针对快速变压吸附制氧浓度和回收率低问题,提出了用于提高产氧浓度和回收率的中间气两步充压的快速真空变压吸附流程,并对该流程进行了研究。结果表明:在快速真空变压吸附制氧过程中,中间气先在出气端充压可以有效提高产氧浓度,之后再在进气端充压可提高氧气回收率。出气端充压前中间气压力及氧浓度和进气端充压后床层压力是影响产氧浓度和回收率提高的关键参数。当吸附和解吸压力分别为240、60 kPa时,循环氧气回收率为34.57%,且每天产单位吨氧需吸附剂量为61.18 kg·TPD-1。 相似文献
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Kensuke Konishi Jun-Ichi Toyooka Kenji Kamiyama Ikken Sato Shigenobu Kubo Shoji Kotake Kazuya Koyama Alexander D. Vurim Valery A. Gaidaichuk Alexander V. Pakhnits Yuri S. Vassiliev 《Nuclear Engineering and Design》2007,237(22):2165-2174
The WF (wall failure) test of the EAGLE program, in which 2 kg of uranium dioxide fuel-pins were melted by nuclear heating, was successfully conducted in the IGR (Impulse Graphite Reactor) of NNC/Kazakhstan. In this test, a 3 mm-thick stainless steel (SS) wall structure was placed between fuel pins and a 10 mm-thick sodium-filled channel (sodium gap). During the transient, fuel pins were heated, which led to the formation of a fuel-steel mixture pool. Under the transient nuclear heating condition, the SS wall was strongly heated by the molten pool, leading to wall failure. The time needed for fuel penetration into the sodium-filled gap was very short (less than 1 s after the pool formation). The result suggests that molten core materials formed in hypothetical LMFBR core disruptive accidents have a certain potential to destroy SS-wall boundaries early in the accident phase, thereby providing fuel escape paths from the core region. The early establishment of such fuel escape paths is regarded as a favorable characteristic in eliminating the possibility of severe re-criticality events. A preliminary interpretation on the WF test results is presented in this paper. 相似文献
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塔河油田盐下探井三开长裸眼井壁稳定问题的探讨 总被引:2,自引:2,他引:2
塔河油田盐下探井设计井深在6300 m左右,三开φ 311.1 mm井段为井深3000~5300 m.在这一井段面临的井眼稳定问题主要是:①侏罗系-三叠系、石炭系上部硬脆性泥岩及二叠系玄武岩地层易剥落和掉块、坍塌,扩径严重;②需要解决裸眼段多个地层压力系统共存和地层岩性差异较大的漏失问题,目前承压堵漏工艺技术还不过关;③巨厚盐膏层的塑性变形极易导致发生缩径卡钻,由于含盐膏泥页岩中的盐溶解及泥页岩的水化分散作用易造成井壁的不稳定性.近期在φ 311.1 mm井段发生了多起事故,例S106-3井、T761井下复合套管卡钻;TK1102井、TK1103井承压堵漏后,在盐膏层钻进中又发生井漏事故等等.因此提出盐下探井三开井段井壁稳定是全井钻井液技术的关键,并针对目前三开井段存在的问题,提出了稳定该井段井壁的技术思路和措施. 相似文献
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滩坝砂岩是东营凹陷西部沙四上亚段的重要沉积储层,超压对滩坝砂岩油气成藏具有明显的控制作用。利用测井参数对超压的响应特征建立了超压成因的判别方法并对超压成因进行了分析,认为东营凹陷沙四上亚段深湖相沉积物的快速沉积埋藏使得欠压实成为超压形成重要因素;沙四上亚段优质烃源岩的广泛发育及热演化使得生烃增压成为超压形成的另一个重要原因。建立了东营凹陷西部增压模式,将超压的演化分为正常压实阶段、欠压实及早期生烃增压阶段以及大量生、排烃增压三个阶段,在超压发育的不同阶段,欠压实与生烃增压先后成为最重要的因素。 相似文献
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针对抽水蓄能机组充水保压蜗壳联合承载结构的受力特性,考虑到钢蜗壳与外包混凝土间的接触传力关系,基于ABAQUS程序平台,引入一种新的不同材料交界面接触单元模型,对某水电站机组蜗壳结构进行非线性接触分析,并将其计算结果与传统简化模型的有限元计算成果及实测资料作比对分析。结果表明:接触单元模型计算成果与实测值较吻合,其更符合工程实际,较好地揭示了充水保压蜗壳复合结构的真实力学行为规律,验证了考虑接触单元模型的合适性,亦为蜗壳结构的优化设计提供了可靠的科学依据。 相似文献