全文获取类型
收费全文 | 467篇 |
免费 | 39篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 240篇 |
金属工艺 | 4篇 |
机械仪表 | 4篇 |
建筑科学 | 17篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 44篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 17篇 |
一般工业技术 | 78篇 |
冶金工业 | 29篇 |
自动化技术 | 57篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 93篇 |
2021年 | 76篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 17篇 |
2017年 | 21篇 |
2016年 | 30篇 |
2015年 | 14篇 |
2014年 | 20篇 |
2013年 | 30篇 |
2012年 | 19篇 |
2011年 | 30篇 |
2010年 | 26篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1982年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有506条查询结果,搜索用时 15 毫秒
161.
Manaenkov Oleg V. Matveeva Valentina G. Sulman Esther M. Filatova Anastasia E. Makeeva Olga Yu. Kislitza Olga V. Sidorov Alexander I. Doluda Valentin Yu. Sulman Mikhail G. 《Topics in Catalysis》2014,57(17):1476-1482
In this paper Ru-containing catalysts based on hypercrosslinked polystyrene (MN-270) and its functional analogues (MN-100 and MN-500) were studied for the first time in cellulose hydrolytic hydrogenation. The catalysts were characterized using transmission electron microscopy (TEM), high resolution TEM, and porosity measurements. Catalytic studies demonstrated that the catalyst containing 1.0 % Ru and based on MN-270 is the most active. The total yield of sorbitol and mannitol was 50 % on the average at 85 % cellulose conversion.
相似文献162.
Vincent Kuek Anastasia M. Hughes Rishi S. Kotecha Laurence C. Cheung 《International journal of molecular sciences》2021,22(13)
In recent decades, the conduct of uniform prospective clinical trials has led to improved remission rates and survival for patients with acute myeloid leukaemia and acute lymphoblastic leukaemia. However, high-risk patients continue to have inferior outcomes, where chemoresistance and relapse are common due to the survival mechanisms utilised by leukaemic cells. One such mechanism is through hijacking of the bone marrow microenvironment, where healthy haematopoietic machinery is transformed or remodelled into a hiding ground or “sanctuary” where leukaemic cells can escape chemotherapy-induced cytotoxicity. The bone marrow microenvironment, which consists of endosteal and vascular niches, can support leukaemogenesis through intercellular “crosstalk” with niche cells, including mesenchymal stem cells, endothelial cells, osteoblasts, and osteoclasts. Here, we summarise the regulatory mechanisms associated with leukaemia–bone marrow niche interaction and provide a comprehensive review of the key therapeutics that target CXCL12/CXCR4, Notch, Wnt/b-catenin, and hypoxia-related signalling pathways within the leukaemic niches and agents involved in remodelling of niche bone and vasculature. From a therapeutic perspective, targeting these cellular interactions is an exciting novel strategy for enhancing treatment efficacy, and further clinical application has significant potential to improve the outcome of patients with leukaemia. 相似文献
163.
Anastasia Gizetdinova ;Svetlana Skornikova ;Sergey Kolesnikov ;Marina Tseljutina ;Irina Reznichenko 《化学与化工:英文版》2014,(5):453-460
This paper deals with the method of zeolites BEA (beta) and MOR (mordenite) synthesis and the co-crystallization method of zeolites BEA/MOR. Synthesized zeolites were studied based on the SEM (scanning electron microscopy), XRD (x-ray diffraction) and chemical analysis. The porous structure of these zeolites was investigated by nitrogen low-temperature adsorption. It has been illustrated that regulation of the BEA/MOR co-crystalline zeolites phase composition is possible due to variations of the initial alumosilicate gels composition and hydrogen ions concentration. Zeolites containing the co-crystalline phases of BEA/MOR could to be attractive in the processes using the catalysts, which based on the pure phases BEA or MOR zeolites. 相似文献
164.
Jeronimo Castrillon Stefan Sch��rmans Anastasia Stulova Weihua Sheng Torsten Kempf Rainer Leupers Gerd Ascheid Heinrich Meyr 《Analog Integrated Circuits and Signal Processing》2011,69(2-3):173-190
With the advent of multi-processor systems on chip (MPSoCs) and due to the complexity and variety of modern wireless standards, academia and industry are moving towards software defined radio (SDR) solutions. It is the goal of the SDR approach to allow designers to describe a radio standard or waveform by means of a high level language. This allows faster waveform development cycles and makes it easier to migrate waveforms across different platforms. Out of many software paradigms, component-based software engineering (CBSE) is an attractive match for SDR, especially for baseband applications. It abstracts waveforms in the traditional way algorithm designers think of their applications and guarantees a high degree of portability. However, existing CBSE approaches for SDR have not been able to close the gap between specification and implementation so as to achieve the computational performance and the energy efficiency of handcrafted solutions. The main reason for this gap is that these flows rely on traditional compilers to lower the high level specification to the platform. The work presented in this paper builds on the Nucleus Concept (Ramakrishnan et al., IEEE Military Communications Conference (MILCOM 2009) [28]) in which computationally intensive kernels and their implementation characteristics on the target platform are known. This information allows a tool to close the performance gap, and thus enables efficient component-based SDR development. In this paper we present such a flow and its supporting environment, which includes state-of-the-art tools for system level design. The flow is demonstrated on a MIMO OFDM transceiver. 相似文献
165.
166.
The exposure of electrospray droplets to vapors of reagents of various base strengths affects protein negative charge state distributions independent of initial solution conditions. Volatile bases are introduced into the counter-current nitrogen drying gas of an electrospray interface to interact with charged droplets as they undergo desolvation/disintegration, shifting charge state distributions of proteins to higher, more negative, charge states. Alterations of charge state distributions can implicate protein folding/unfolding phenomena. Species bound by relatively weak interactions can be preserved, at least to some extent, allowing for the observation of high charge states of protein-ligand complexes, such as high negative charge states of holomyoglobin. The binding of carbonic anhydrase with its Zn(2+) cofactor is apparently preserved when the holo-form of the protein is exposed to basic vapors (i.e., the Zn(2+) ion remains associated with the protein), but this prevents the appearance of charge states higher than -17. Charge state distributions of proteins containing disulfide bonds shift slightly with the leak-in of basic vapors, but when these disulfide bonds are reduced with dithiothreitol in solution, charge states higher than the number of acidic sites (Asp, Glu, and C-terminus) are observed. Since there is no observed change in the distributions of buffered proteins exposed to these reagent vapors, the charge state changes are attributed largely to a pH affect. High pK(a) and highly volatile reagents have been found to be the most effective in terms of observing the maximum negative charge state of the biomolecule of interest. 相似文献
167.
Anastasia Loukaitou-Sideris 《Journal of the American Planning Association. American Planning Association》2013,79(3):198-217
Problem, research strategy, and findings: College campuses are multimodal settings with very high levels of walking and biking in conjunction with high levels of vehicular traffic, which increases risks for bicyclists and pedestrians. In this study, we examine crash data (both police reported and self-reported) and urban form data from three U.S. campuses to understand the spatial and temporal distribution of crashes on the campuses and their immediate periphery. To account for underreporting of pedestrian and bicycle crashes, we developed and circulated an online survey, which helped identify collision hotspots across the three campuses. We then studied these locations to determine their characteristics, generate a typology of campus danger zones, and recommend design and policy changes that could improve pedestrian and cycling safety. We find a significant underreporting of crashes, and unequal spatial and temporal distributions of campus crashes. We identify three particular types of danger zones for pedestrians and cyclists: campus activity hubs, campus access hubs, and through traffic hubs. Injuries tended to be more serious for those crashes taking place on campus peripheries.Takeaway for practice: The intermingling of motorized and non-motorized modes creates significant opportunities for crashes. Planners should be aware of the existing underreporting and give special attention to the three types of danger zones. In addition to the recommendations of the literature for the creation of campus master plans for walking and biking, campuses should conduct safety audits and surveys to identify hotspots and consider specific design improvements for each of the three danger zones to lessen modal conflict. 相似文献
168.
Anastasia Loukaitou-Sideris Martin Wachs Miriam Pinski 《Journal of the American Planning Association. American Planning Association》2013,79(4):482-500
Problem, research strategy, and findings: People older than 65 are the most rapidly growing segment of the U.S. population, yet our cities and transportation systems are not age friendly. Low-income, minority, older adults residing in inner-city neighborhoods are largely transit dependent, rely significantly on walking for transportation, and thus have particular mobility needs. We used a mixed-methods approach that drew information from the California Household Travel Survey but also from direct interaction (through focus groups, interviews, and neighborhood walking audits) with 81 low-income, inner city–living older adults to understand their travel patterns and mobility challenges and needs. We find that despite some positive mobility indicators in the inner city (mixed-use environment, frequent bus service, and short travel distances), these elders face significant mobility challenges because of a deteriorated built environment, heavy traffic, homelessness, and crime. A limitation of this research is that the small sample did not allow the study of possible gender or race/ethnicity differentiation in the travel patterns and needs of older adults.Takeaway for practice: Planners should not rely only on information from the census and other aggregate data sources to understand the mobility needs of older adults but should complement this information with direct interaction with the communities for which they are planning. Although some social problems limiting the mobility of older adults are difficult to tackle, environmental and streetscape improvements can significantly enhance their mobility. 相似文献
169.
The effects of goal setting and self-monitoring during self-regulated practice on the acquisition of a complex motoric skill were studied with 90 high school girls. It was hypothesized that girls who shifted goals developmentally from process to outcome goals would surpass classmates who adhered to only process goals who, in turn, would exceed classmates who used only outcome goals in posttest dart-throwing skill, self-reactions, self-efficacy perceptions, and intrinsic interest in the game. Support for all hypotheses derived from the developmental model was found. The girls' self-reactions to dart-throwing outcomes and self-efficacy perceptions about dart skill were highly correlated with their intrinsic interest in the game. It was also found that self-recording, a formal form of self-monitoring, enhanced dart-throwing skill, self-efficacy, and self-reaction beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
170.
E Tragni M Marinovich P Ciuffreda M Anastasia A Ferrari C L Galli 《Food Additives & Contaminants》1990,7(1):1-7
An in vitro system consisting of a bacterial suspension of human or rat faecal microflora brought about the biological reduction of the red azo dye [14C]carmoisine to 1-naphthyl-amine-4-sulphonic acid (NA) and 2-amino-1-naphthol-4-sulphonic acid (ANA). These metabolites have been unequivocally identified by radio-HPLC, spectroscopic methods, dilution with cold authentic standards and evidence that the specific activity of the diluted compounds remained constant throughout repeated crystallization, acetylation and purification. The results clearly indicated that samples derived from anaerobic incubations have to be processed for analysis in the complete absence of oxygen. In the presence of oxygen, the formation of a complex pattern of compounds in addition to NA was observed as a consequence of the chemical decomposition of ANA. 相似文献