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491.
ABSTRACT: Water sorption properties, effects of proteins on glass transition temperature, and time-dependent lactose crystallization of spray-dried lactose and lactose in lactose/WPI (3:1), lactose/Na-caseinate (3:1), lactose/albumin (3:1), and lactose/gelatin (3:1) mixtures were investigated. Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were used to model water sorption. Lactose/protein mixtures sorbed high amounts of water at low relative vapor pressure (RVP) up to 23.1%. Above 23.1% RVP levels, water sorbed by pure lactose was higher, up to 44.1% RVP, except in the case of the lactose/gelatin mixture. Lactose/ gelatin also sorbed a high amount of water at 33.2% RVP. Loss of sorbed water resulting from crystallization of amorphous lactose was observed. Crystallization of pure lactose and lactose crystallization in lactose/protein mixtures occurred at RVP ≥ 44.1% within 24 h. After crystallization at RVP ≥ 54.5%, water contents remained higher for lactose/protein mixtures than for pure lactose. The rate of lactose crystallization was less in all lactose/protein mixtures than was observed for pure lactose. WPI had the lowest effect on lactose crystallization. Crystallization occurred most slowly in lactose/gelatin mixtures. Both GAB and BET models fitted to water sorption data up to 0.441 aw. It seems that different proteins interact with lactose differently. Water sorption and time-dependent lactose crystallization of lactose/protein mixtures have important consequences to processing and storage behavior of lactose-protein based products.  相似文献   
492.
This paper examines the impact of community based fish culture in seasonal floodplains on fish production, consumption, income, and food security of the participating households in Bangladesh. An analysis was performed using a randomly selected 46 % of the households from the three project and control floodplains; data were collected using longitudinal surveys on a seasonally, quarterly and monthly basis for the years 2007, 2008 and 2009. Fish production, income and food security of the participating households was improved due to the adoption of an equitable and inclusive multi-stakeholder approach introduced by the project. Average fish production increased from 124 kg/ha/yr. to 464 kg/ha/yr. The introduced community-based fish culture approach generated 3.74 times more fish income for households in the project sites in comparison to the control sites. Per capita monthly fish consumption increased from 1.26 kg to 2.31 kg in the project sites, which was 32 % higher than the control sites. Project implementation reduced the vulnerability of local beneficiaries, particularly of the landless and poor fishermen, by creating additional fishing opportunity for up to 6 months of the year. Promotion of the community based fish culture in seasonal floodplains may thus be useful in bringing about positive changes in the overall floodplain productivity and livelihood gains for the poor people of Bangladesh.  相似文献   
493.
Ruminant production systems are important contributors to anthropogenic methane (CH4) emissions, but there are large uncertainties in national and global livestock CH4 inventories. Sources of uncertainty in enteric CH4 emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH4 emission factors. There is also significant uncertainty associated with enteric CH4 measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF6) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH4 emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH4 emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH4 prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH4 emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH4 prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH4 emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.  相似文献   
494.
The paper presents results on strength development and durability of 35 and 50 MPa total lightweight and 50 MPa normal weight concretes exposed to hot marine exposure conditions for a period of two years. An initial water curing of 7 days and subsequent seaside exposure is more beneficial for the strength development of light-weight concrete than it is for normal weight concrete. One day initial curing and subsequent seaside exposure was not very conductive for the strength development of both lightweight and normal weight concretes. The water penetrability of total lightweight concretes was found higher than the normal weight concrete under all the initial curing conditions and on subsequent exposure to the hot-marine environment. In the same vein, the depth of carbonation for the total lightweight concretes was more than that of the normal weght concrete. On the overall, the results suggest that the higher the water penetrability of a given concrete, the more is the penetration of the damaging species like carbon dioxide, sulphate and chloride ions into a concrete.  相似文献   
495.
Lightweight concrete in hot coastal areas   总被引:5,自引:0,他引:5  
An experimental study was carried out to examine different mixtures made with selected lightweight aggregates for the purpose of producing lightweight concrete. A relatively suitable product is sought in order to provide good quality building materials that can satisfy the conditions of hot coastal environments. Three ways of producing lightweight concrete were used, i.e., lightweight crushed bricks, lightweight expanded clay aggregate (LECA), and no-fines concrete. Physical and mechanical properties of the mixtures were examined to ascertain the suitability and applicability of the three concretes. The results of this pilot study suggest that there are possibilities of producing structural lightweight concrete using crushed bricks with the condition of further refinements in the mixture design.  相似文献   
496.
This paper provides information encompassing the recent discovery of the High Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC) focusing on systems requirement. To have a reliable power production and higher durability level, a proper system must be applied in both normal and especially in transient operations. To date many issues of HT-PEMFC especially in durability and performance still unsolved. This article is written to provide clear information about the research undergo and must be the focus in order to produce an efficient performance. Information about the advantages towards Low Temperature Proton Exchange Membrane Fuel Cell (LT-PEMFC), the main components, and the mode of operation also discussed. In-depth research needs to be conducted into the innovative design and development of HT-PEMFC components and its system since these are the key factors for optimum performance.  相似文献   
497.
Parkinson’s disease (PD) is a neurodegenerative disease characterized by the loss of dopamine neurons and the deposition of misfolded proteins known as Lewy bodies (LBs), which contain α-synuclein (α-syn). The causes and molecular mechanisms of PD are not clearly understood to date. However, misfolded proteins, oxidative stress, and impaired autophagy are believed to play important roles in the pathogenesis of PD. Importantly, α-syn is considered a key player in the development of PD. The present study aimed to assess the role of Ellagic acid (EA), a polyphenol found in many fruits, on α-syn aggregation and toxicity. Using thioflavin and seeding polymerization assays, in addition to electron microscopy, we found that EA could dramatically reduce α-syn aggregation. Moreover, EA significantly mitigated the aggregated α-syn-induced toxicity in SH-SY5Y cells and thus enhanced their viability. Mechanistically, these cytoprotective effects of EA are mediated by the suppression of apoptotic proteins BAX and p53 and a concomitant increase in the anti-apoptotic protein, BCL-2. Interestingly, EA was able to activate autophagy in SH-SY5Y cells, as evidenced by normalized/enhanced expression of LC3-II, p62, and pAKT. Together, our findings suggest that EA may attenuate α-syn toxicity by preventing aggregation and improving viability by restoring autophagy and suppressing apoptosis.  相似文献   
498.
Non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation eventually develop resistance to EGFR-targeted tyrosine kinase inhibitors (TKIs). Treatment resistance remains the primary obstacle to the successful treatment of NSCLC. Although drug resistance mechanisms have been studied extensively in NSCLC, the regulation of these mechanisms has not been completely understood. Recently, increasing numbers of microRNAs (miRNAs) are implicated in EGFR-TKI resistance, indicating that miRNAs may serve as novel targets and may hold promise as predictive biomarkers for anti-EGFR therapy. MicroRNA-506 (miR-506) has been identified as a tumor suppressor in many cancers, including lung cancer; however, the role of miR-506 in lung cancer chemoresistance has not yet been addressed. Here we report that miR-506-3p expression was markedly reduced in erlotinib-resistant (ER) cells. We identified Sonic Hedgehog (SHH) as a novel target of miR-506-3p, aberrantly activated in ER cells. The ectopic overexpression of miR-506-3p in ER cells downregulates SHH signaling, increases E-cadherin expression, and inhibits the expression of vimentin, thus counteracting the epithelial–mesenchymal transition (EMT)-mediated chemoresistance. Our results advanced our understanding of the molecular mechanisms underlying EGFR-TKI resistance and indicated that the miR-506/SHH axis might represent a novel therapeutic target for future EGFR mutated lung cancer treatment.  相似文献   
499.
Growing application of distributed generation units at remote places has led to the evolution of microgrid (MG) technology. When an MG system functions independently, i.e., in autonomous mode, unpredictable loads and uncertainties emerge throughout the system. To obtain stable and flexible operation of an autonomous MG, a rigid control mechanism is needed. In this paper, a robust high-performance controller is introduced to improve the performance of voltage tracking of an MG system and to eliminate stability problems. A combination of a resonant controller and a lead-lag compensator in a positive position feedback path is designed, one which obeys the negative imaginary (NI) theorem, for both single-phase and three-phase autonomous MG systems. The controller has excellent tracking performance. This is investigated through considering various uncertainties with different load dynamics. The feasibility and effectiveness of the controller are also determined with a comparative analysis with some well-known controllers, such as linear quadratic regulator, model predictive and NI approached resonant controllers. This confirms the superiority of the designed controller.  相似文献   
500.
The natural substance class of terpenoids covers an extremely wide range of different structures, although their building block repertoire is limited to the C5 compounds DMAPP and IPP. This study aims at the characterization of methyltransferases (MTases) that modify these terpene precursors and the demonstration of their suitability for biotechnological purposes. All seven enzymes tested accepted IPP as substrate and altogether five C6 compounds and six C7 compounds were formed within the reactions. A high selectivity for the deprotonation site as well as high stereoselectivity could be observed for most of the biocatalysts. Only the enzyme from Micromonospora humi also accepted DMAPP as substrate, converting it into (2R)-2-methyl-IPP in vitro. In vivo studies demonstrated the production of a C8 compound and a hydride shift step within the MTase-catalyzed reaction. Our study presents IPP/DMAPP MTases with very different catalytic properties, which provide biosynthetic access to many novel terpene-derived structures.  相似文献   
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