全文获取类型
收费全文 | 297篇 |
免费 | 19篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 73篇 |
金属工艺 | 2篇 |
机械仪表 | 6篇 |
建筑科学 | 9篇 |
能源动力 | 19篇 |
轻工业 | 48篇 |
水利工程 | 2篇 |
无线电 | 19篇 |
一般工业技术 | 80篇 |
冶金工业 | 20篇 |
原子能技术 | 2篇 |
自动化技术 | 32篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 17篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 18篇 |
2013年 | 15篇 |
2012年 | 22篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1983年 | 6篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有316条查询结果,搜索用时 15 毫秒
51.
Bhanjan Debnath K. Kesava Rao Prabhu R. Nott 《American Institute of Chemical Engineers》2017,63(12):5482-5489
The discrete element method has been used to study the lift FL on a stationary disc immersed coaxially in a slowly rotating cylinder containing a granular material. In a tall granular column, FL rises with the immersion depth h, but reaches a roughly constant asymptote at large h, in agreement with previous studies. Our results indicate that the argument in some earlier studies that FL is proportional to the static stress gradient is incorrect. Instead, our results show that the lift is caused by an asymmetry in the dilation and shear rate between the regions above and below the disc. We argue that the cause of the lift is similar to that in fluids, namely that it arises as a result of the disturbance in the velocity and density fields around the body due to its motion relative to the granular bed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5482–5489, 2017 相似文献
52.
A. N. Spector Lay James Gibson Ashok K. Dutt William F. Hyde Paul B. Sherman Hans-Jurg Buttler Bernard Malamud Robert N. Anderson M. Penouil R. W. Keyes Lee R. McPheters William R. Eadington Kurt Puchinger Arthur E. Kartman Charles E. Starnes J. Barry Riddell Erick Sheppard Leon E. Zonn Craig Moore Neil S. Grigg K. Shimizu Daniel A. Griffith Noel D. Uri Micheal Ross Jack E. Adams Robert G. Fletcher Karol J. Krotki Peter D. Beaulieu Fred E. Case W. Edwin Derrick Barry D. Solomon Debnath Mookherjee John E. Keith Yuk Lee Andrew A. Dzurik W. W. Hall Jr. Lloyd W. Klemke Ted J. Adamczyk 《The Annals of Regional Science》1981,15(3):82-146
53.
Philip J. Bourque Dominique Gambier Raymond J. Burby III Jack E. Adams Jeffrey B. Nugent D. van der Werf William J. Serow Edward L. Prill Willard Tim Chow R. J. Johnston Craig Zumbrunnen Kingsley E. Haynes Nolin Masih Robert Hines Wilson Philip S. Morrison Debnath Mookherjee Robin Flowerdew Noel D. Uri Panayotis H. Mavrakis Leo E. Zonn Joseph A. Ziegler J. S. L. McCombie Ronald A. Oliveira Jacob J. van Duijn Douglas M. Brown Robert G. Fletcher Lawrence Hugg W. T. Trulove Alene Anderson Bruce Domazllcky 《The Annals of Regional Science》1978,12(1):105-164
54.
55.
Bing Guan Ning Zhou Cheng-Yang Wu Songye Li Yu-An Chen Sashi Debnath Mia Hofstad Shihong Ma Ganesh V. Raj Dalin He Jer-Tsong Hsieh Yiyun Huang Guiyang Hao Xiankai Sun 《International journal of molecular sciences》2021,22(23)
Neuroendocrine prostate cancer (NEPC) is an aggressive and lethal variant of prostate cancer (PCa), and it remains a diagnostic challenge. Herein we report our findings of using synaptic vesicle glycoprotein 2 isoform A (SV2A) as a promising marker for positron emission tomography (PET) imaging of neuroendocrine differentiation (NED). The bioinformatic analyses revealed an amplified SV2A gene expression in clinical samples of NEPC versus castration-resistant PCa with adenocarcinoma characteristics (CRPC-Adeno). Importantly, significantly upregulated SV2A protein levels were found in both NEPC cell lines and tumor tissues. PET imaging studies were carried out in NEPC xenograft models with 18F-SynVesT-1. Although 18F-SynVesT-1 is not a cancer imaging agent, it showed a significant uptake level in the SV2A+ tumor (NCI-H660: 0.70 ± 0.14 %ID/g at 50–60 min p.i.). The SV2A blockade resulted in a significant reduction of tumor uptake (0.25 ± 0.03 %ID/g, p = 0.025), indicating the desired SV2A imaging specificity. Moreover, the comparative PET imaging study showed that the DU145 tumors could be clearly visualized by 18F-SynVesT-1 but not 68Ga-PSMA-11 nor 68Ga-DOTATATE, further validating the role of SV2A-targeted imaging for noninvasive assessment of NED in PCa. In conclusion, we demonstrated that SV2A, highly expressed in NEPC, can serve as a promising target for noninvasive imaging evaluation of NED. 相似文献
56.
Thiuram disulfides form synergistic combinations with thiazole and thiazole-based accelerators, namely, N-cyclohexy-2-benzothiazole sulfenamide (CBS), 2-mercaptobenzothiazole(MBT), and 2-mercaptobenzothiazyl disulfide (MBTS). Unfortunately, widely used thiuram disulfides (TD) generate carcinogenic N-nitrosoamine. It is reported that the nitrosamines from N-methylpiperazine and dibenzylamine are free from this menace. So, some investigations were carried out with the binary combinations of each of bis(N-methylpiperazino)thiuram disulfide (MPTD), tetrabenzylthiuram disulnde (TBzTD), and tetramethyl-thiuram disulfide (TMTD) separately with CBS, MBT, and MBTS. It was observed that all the TD are activated by the CBS, MBT, or MBTS in the combinations studied. The intensity of activation is manifested in the enhancement of torque, modulus, tensile strength, cure rate, hardness, and decrease of elongation at break values and is very much dependent upon the ratio of the accelerators used. Considering the torque, modulus, tensile strength, and the elongation at break values, it apears that MPTD and TBzTD are capable of competing with the hitherto unbeaten TMTD as suitable accelerators for the vulcanization of rubber. Some investigations in respect to heat- and age-resistance behavior have also been carried out and the observed differences in the activities of various binary combinations have been explained through a mechanism. The results obtained with filled vulcanizates indicate that the binary systems comprising TD and MBTS provide fruitful results of which the TBzTD–MBTS combination seems to give the best cure and physical data for practical vulcanizates. © 1996 John Wiley & Sons, Inc. 相似文献
57.
Spectrally resolved white-light phase-shifting interference microscopy can be used for rapid and accurate measurements of the thickness profile of transparent thin-film layers deposited upon patterned structures exhibiting steps and discontinuities. We examine the sensitivity of this technique and show that it depends on the thickness of the thin-film layer as well as its refractive index. The results of this analysis are also valid for any other method based on measurements of the spectral phase such as wavelength scanning or white-light interferometry. 相似文献
58.
59.
Zhitomirsky D Kramer IJ Labelle AJ Fischer A Debnath R Pan J Bakr OM Sargent EH 《Nano letters》2012,12(2):1007-1012
The size-effect tunability of colloidal quantum dots enables facile engineering of the bandgap at the time of nanoparticle synthesis. The dependence of effective bandgap on nanoparticle size also presents a challenge if the size dispersion, hence bandgap variability, is not well-controlled within a given quantum dot solid. The impact of this polydispersity is well-studied in luminescent devices as well as in unipolar electronic transport; however, the requirements on monodispersity have yet to be quantified in photovoltaics. Here we carry out a series of combined experimental and model-based studies aimed at clarifying, and quantifying, the importance of quantum dot monodispersity in photovoltaics. We successfully predict, using a simple model, the dependence of both open-circuit voltage and photoluminescence behavior on the density of small-bandgap (large-diameter) quantum dot inclusions. The model requires inclusion of trap states to explain the experimental data quantitatively. We then explore using this same experimentally tested model the implications of a broadened quantum dot population on device performance. We report that present-day colloidal quantum dot photovoltaic devices with typical inhomogeneous linewidths of 100-150 meV are dominated by surface traps, and it is for this reason that they see marginal benefit from reduction in polydispersity. Upon eliminating surface traps, achieving inhomogeneous broadening of 50 meV or less will lead to device performance that sees very little deleterious impact from polydispersity. 相似文献
60.
Hybrid passivated colloidal quantum dot solids 总被引:1,自引:0,他引:1
AH Ip SM Thon S Hoogland O Voznyy D Zhitomirsky R Debnath L Levina LR Rollny GH Carey A Fischer KW Kemp IJ Kramer Z Ning AJ Labelle KW Chou A Amassian EH Sargent 《Nature nanotechnology》2012,7(9):577-582
Colloidal quantum dot (CQD) films allow large-area solution processing and bandgap tuning through the quantum size effect. However, the high ratio of surface area to volume makes CQD films prone to high trap state densities if surfaces are imperfectly passivated, promoting recombination of charge carriers that is detrimental to device performance. Recent advances have replaced the long insulating ligands that enable colloidal stability following synthesis with shorter organic linkers or halide anions, leading to improved passivation and higher packing densities. Although this substitution has been performed using solid-state ligand exchange, a solution-based approach is preferable because it enables increased control over the balance of charges on the surface of the quantum dot, which is essential for eliminating midgap trap states. Furthermore, the solution-based approach leverages recent progress in metal:chalcogen chemistry in the liquid phase. Here, we quantify the density of midgap trap states in CQD solids and show that the performance of CQD-based photovoltaics is now limited by electron-hole recombination due to these states. Next, using density functional theory and optoelectronic device modelling, we show that to improve this performance it is essential to bind a suitable ligand to each potential trap site on the surface of the quantum dot. We then develop a robust hybrid passivation scheme that involves introducing halide anions during the end stages of the synthesis process, which can passivate trap sites that are inaccessible to much larger organic ligands. An organic crosslinking strategy is then used to form the film. Finally, we use our hybrid passivated CQD solid to fabricate a solar cell with a certified efficiency of 7.0%, which is a record for a CQD photovoltaic device. 相似文献