全文获取类型
收费全文 | 416篇 |
免费 | 30篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 96篇 |
金属工艺 | 8篇 |
机械仪表 | 9篇 |
建筑科学 | 10篇 |
能源动力 | 9篇 |
轻工业 | 51篇 |
无线电 | 37篇 |
一般工业技术 | 87篇 |
冶金工业 | 77篇 |
原子能技术 | 2篇 |
自动化技术 | 56篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 18篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 33篇 |
2012年 | 15篇 |
2011年 | 31篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 10篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 338 毫秒
31.
Rosario Barón Manuel Mayen Julieta Merida M. Medina 《European Food Research and Technology》1997,205(6):474-478
Changes in the concentrations of hydroxybenzoic acids, hydroxycinnamic acids and their esters, monomeric and dimeric derivatives
of flavan-3-ol, and flavonols, as well as in the UV-visible absorbances of pale Sherry wines were studied. The wines were
subjected to four different fining treatments: casein + bentonite, casein + bentonite + activated charcoal, casein + bentonite
+ polyvinylpyrrolidone (PVPP) and casein + bentonite + Riduxhigh. Based on the results, the treatments including activated
charcoal and PVPP were the most effective at decreasing the overall concentration phenolic compounds, with no significant
difference between them. Likewise, these treatments provided the best results in relation to wine colour in the visible spectral
region, and particularly at 420 nm, at which wavelength browning compounds are usually measured.
Received: 24 March 1997 / Revised version: 11 June 1997 相似文献
32.
33.
Teaching inter‐disciplinary material poses special challenges due to the diversity of student backgrounds. This problem is compounded if the material being taught is intended for both undergraduate and graduate students. Mechanical Engineering faculty members from three universities have come together to address this problem using a layered, multimedia delivery mechanism via the Internet. This has resulted in the first‐ever, live, full‐duplex, Internet course taught at any of the three partner universities: Auburn University, the University of Maryland, and the University of Minnesota. With the addition of colleagues from industrial sites such as Philips in the Netherlands and three other universities in Japan, Singapore, and Australia, the next offering will expand to become an international course. The authors hope to illustrate that a course delivered over the Internet adds significantly to the learning process in a cost‐effective manner . 相似文献
34.
35.
Sean Poust James Piety Dr. Arren Bar‐Even Dr. Catherine Louw Prof. Dr. David Baker Prof. Dr. Jay D. Keasling Prof. Dr. Justin B. Siegel 《Chembiochem : a European journal of chemical biology》2015,16(13):1950-1954
An enzyme that catalyzes the formose reaction, termed “formolase”, was recently engineered through a combination of computational protein design and directed evolution. We have investigated the kinetic role of the computationally designed residues and further characterized the enzyme's product profile. Kinetic studies illustrated that the computationally designed mutations were synergistic in their contributions towards enhancing activity. Mass spectrometry revealed that the engineered enzyme produces two products of the formose reaction—dihydroxyacetone and glycolaldehyde—with the product profile dependent on the formaldehyde concentration. We further explored the effects of this product profile on the thermodynamics and yield of the overall carbon assimilation from the formolase pathway to help guide future efforts to engineer this pathway. 相似文献
36.
Mobile Design as Neighborhood Acupuncture: Activating the Storytelling Networks of South Los Angeles
AbstractA delicate touch is required to empower neighborhoods using civic media. Funding is persistently scarce. Especially in marginalized neighborhoods, blunt designs can be counterproductive and even entrench complex problems. New metaphors may be needed to guide design and empower local neighborhoods. Urban acupuncture is used as the basis for this study, emphasizing a light-touch strategy that has shown success in Brazil with urban transit, and more recently in Europe with urban design. We specifically propose “neighborhood acupuncture” to address the local level, tapping the sociology of place-based communication. To investigate the implications for systematic design, a case study is probed in South Los Angeles using mobile media for community mapping. Using qualitative methods, three tactics were investigated for the potential to “poke” the network into action, including one to bridge diverse storytelling networks. Each tactic ultimately seeks to build the capacity for collective action around neighborhood issues. Acupuncture is broadly argued to sustain two design shifts: first to help approach neighborhoods as ecosystems, and second, to design for circulation rather than any single technology platform. 相似文献
37.
Petr Ptáček Tomáš Opravil František Šoukal Jaromír Wasserbauer Jiří Másilko Jan Baráček 《Journal of the European Ceramic Society》2013,33(13-14):2793-2799
The structural order of kaolinite is an important factor that shows a substantial effect on the processes which take place during the thermal treatment of kaolin. The influence of structural order on the dehydroxylation process was investigated by simultaneous thermogravimetry and differential thermal analysis (TG-DTA). The thermal analysis was performed on the samples with gradually decreasing structural order prepared by milling procedure. The apparent activation energy of dehydroxylation process decreases with decreasing structural order according to the exponential function. The extrapolation of experimental data leads to the estimation of apparent activation energy of 76.6 kJ mol?1 and of frequency factor of 0.12 × 104 s?1 related to completely disordered form of kaolinite, while the ordered form shows the apparent activation energy of 216.17 kJ mol?1 and the frequency factor of 9.26 × 104 s?1. The relationships between features such as the infrared pattern of treated material, the degree of structural order and the apparent activation energy were established. 相似文献
38.
A flow injection analysis method for the determination of glycine, based on the reaction with ortho-phtalaldehyde and N-acetylcysteine in a basic buffer, was optimised. In the first step screening of the variables, to select the most important ones, was performed using: (i) a half-fraction factorial design and (ii) a quarter-fraction factorial design, for five factors at two levels. The effects of the factors on the peak height were calculated from both screening designs and compared. For the half-fraction factorial design (resolution IV), the significance of the factor effects on the peak height was checked by: (i) comparing them with a critical effect, calculated from two-factor interactions and based on a t-test, (ii) using a non parametric approach and (iii) drawing a normal probability plot. For the quarter-fraction factorial design (resolution III) the significance of the effects of the factors on the peak height was checked using: (i) a randomization test method, (ii) the non parametric method and (iii) a normal probability plot. In the second step, the factor found to be of importance was optimised using the uniplex method. 相似文献
39.
Pavel Kagan Anath Fischer Pinhas Z. Bar‐Yoseph 《International journal for numerical methods in engineering》2003,57(8):1145-1175
This article presents two new methods for adaptive refinement of a B‐spline finite element solution within an integrated mechanically based computer aided engineering system. The proposed techniques for adaptively refining a B‐spline finite element solution are a local variant of np‐refinement and a local variant of h‐refinement. The key component in the np‐refinement is the linear co‐ordinate transformation introduced into the refined element. The transformation is constructed in such a way that the transformed nodal configuration of the refined element is identical to the nodal configuration of the neighbour elements. Therefore, the assembly proceeds as with classic finite elements, while the solution approximation conforms exactly along the inter‐element boundaries. For the h‐refinement, this transformation is introduced into a construction that merges the super element from the finite element world with the hierarchical B‐spline representation from the computational geometry. In the scope of developing sculptured surfaces, the proposed approach supports C0 as well as the Hermite B‐spline C1 continuous shapes. For sculptured solids, C0 continuity only is considered in this article. The feasibility of the proposed methods in the scope of the geometric design is demonstrated by several examples of creating sculptured surfaces and volumetric solids. Numerical performance of the methods is demonstrated for a test case of the two‐dimensional Poisson equation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
40.
PJ Cagnoni Y Nieto EJ Shpall SI Bearman AE Barón M Ross S Matthes SE Dunbar RB Jones 《Canadian Metallurgical Quarterly》1998,16(5):1661-1668
PURPOSE: To evaluate the feasibility of high-dose chemotherapy (HDC) with autologous hematopoietic progenitor-cell support (AHPCS) as part of combined modality therapy (CMT) in patients with inflammatory breast cancer (IBC). PATIENTS AND METHODS: From April 1993 to March 1997, 30 patients with IBC were treated at our program. Twenty-three patients received neoadjuvant chemotherapy (NAC) before HDC; 18 patients also received adjuvant chemotherapy following surgery, but before HDC. All patients received HDC with high-dose cyclophosphamide, cisplatin, and carmustine (BCNU) with AHPCS. Every patient underwent surgery either before (27 patients) or after (three patients) HDC. Patients received radiotherapy after HDC in addition to tamoxifen if their tumors were estrogen receptor-positive. RESULTS: Thirteen patients experienced grade 3 or 4 nonhematologic noninfectious toxicities. In 12 patients (40%), this represented drug-induced lung injury, which in all cases responded to a 10-week course of corticosteroids. The only treatment-related death was secondary to hemolytic-uremic syndrome (HUS). Another patient suffered grade 4 CNS toxicity, which was completely reversible. All patients engrafted promptly. Eight patients relapsed, five of whom had a poor pathologic response to NAC. Relapses were local (five patients), local plus systemic (one), or systemic only (two). Median follow-up time from diagnosis and HDC is 23.5 (range, 7 to 49) and 19 (range, 4 to 44) months, respectively. Twenty-one patients (70%; 95% confidence interval [CI], 51% to 86%) remain alive and free of disease 4 to 44 months after HDC. Median disease-free survival (DFS) and overall survival have not yet been reached. CONCLUSION: HDC as part of CMT is feasible in patients with IBC. The toxicity of this treatment program is significant, but tolerable. Despite the short follow-up duration, the promising DFS observed in this group of patients warrants randomized studies that include a HDC-containing arm in patients with IBC. 相似文献