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91.
Thermal degradation of Athabasca oil sands, bitumen, and its fractions have been investigated in N2and in air, at 25–600 °C and at pressures up to 6.9 MPa, using thermogravimetry (TG) and high pressure differential scanning calorimetry (PDSC). These conditions are likely to occur during in-situ recovery of bitumen by underground combustion processes. Two regions of weight loss are detected using both gases. The endothermic low temperature volatilization reactions (150–400 °C) absorbed +26 mJ mg?1 for oil sand to +2319 mJ mg?1 for medium oil. The heats of reaction for high-temperature cracking and volatilization reactions (400–550 °C) were similar. The heats of reaction for the low-temperature oxidation reactions (150–375 °C) were ?405 mJ mg?1 for oil sand to ?30200mJ mg?1 for medium oil. Values for the high-temperature oxidation reactions (400–550 °C) were slightly higher. Increasing the pressure of nitrogen and air caused an increase in the endothermicity and exothermicity of the respective reactions. 相似文献
92.
Mahmoud MOUSTAFA Saad ALAMRI Hoida ZAKI Naglaa LOUTFY Tarek TAHA Ali SHATI Mohamed ALKAHTANI Sajda SIDDIQI 《Biocell》2019,43(2):81-88
The present research reports of quick and marked changes induced by plant extract of Euryops arabicus in the
gene expression of 49-kDa apyrases, cytoskeletal proteins, ATPases, ADPase and amount of amino acid of pea (Pisum
sativum L. var. Alaska). Pellets of cytoskeletals proteins (27000 xg) were probed with anti-apyrase antibody, biotinylated
anti-rat, actin and alpha and beta-tubulin for Western blotting. ATPase and ADPase activities were determined based
on the hydrolytic efficacy of adenine triphosphate and adenine diphosphate. By 72 hours, the abundance of apyrases,
cytoskeletal proteins and amount of amino acid in pellets of 27000 xg of germinated pea seeds in E. arabicus extracts
were sharply increased than those sown in distilled water. All the samples exhibited that the stems had more amount
from apyrases, cytoskeletal proteins, amino acids and ATPase and ADPase activities than primary leaves and primary
roots that were germinated either on E. arabicus water extract or in distilled water. Based on the enzyme’s capability to
hydrolyse nucleotide triphosphate and nucleotide diphosphate as well as the direct association between expression of
49-kDa apyrase and cytoskeletal proteins, E. arabicus water extract had an important effect on plant germinations. 相似文献
93.
94.
Rejab Hajlaoui Eesa Alsolami Tarek Moulahi Herv Guyennet 《International Journal of Communication Systems》2019,32(12)
Recently, the routing problem in vehicular ad hoc networks is one of the most vital research. Despite the variety of the proposed approaches and the development of communications technologies, the routing problem in VANET suffers from the high speed of vehicles and the repetitive failures in communications. In this paper, we adjusted the well‐known K‐medoids clustering algorithm to improve the network stability and to increase the lifetime of all established links. First, the number of clusters and the initial cluster heads will not be selected randomly as usual, but based on mathematical formula considering the environment size and the available transmission ranges. Then the assignment of nodes to clusters in both k‐medoids phases will be carried out according to several metrics including direction, relative speed, and proximity. To the best of our knowledge, our proposed model is the first that introduces the new metric named “node disconnection frequency.” This metric prevents nodes with volatile and suspicious behavior to be elected as a new CH. This screening ensures that the new CH retains its property as long as possible and thus increases the network stability. Empirical results confirm that in addition to the convergence speed that characterizes our adjusted K‐medoids clustering algorithm (AKCA), the proposed model achieves more stability and robustness when compared with most recent approaches designed for the same objective. 相似文献
95.
Because of the superior photocatalytic activities of nanocrystalline TiO2 and ZnO under UV irradiation, they were embedded into the glass system (SiO2, TiO2, ZnO, B2O3, Na2O, K2O, P2O5, Li2O and BaO) to provide easy separation from the aqueous system. Different contents of TiO2 and ZnO have been investigated. Conversion to glass-ceramic materials was carried out by heat treatment at 450 °C, which is the onset of the nucleation peak according to the differential thermal analysis (DTA) result, for different times. This heat treatment regime preserves the transparency of the prepared materials in the visible region and good absorption in the UV region. The high content of TiO2 or ZnO caused an improvement of microhardness of the prepared materials, though the presence of the two oxides with the same ratio decreased the microhardness values. Photocatalytic activity of the prepared glass-ceramic materials was investigated according to their efficiency for the degradation of humic acid (HA), the major precursor of disinfection by-products (DBPs), from water. All samples were proved to be photoactive with different extents. Four hours heat treatment at 450 °C appears to be the best conditions for the development of TiO2 and ZnO crystals leading to better photocatalytic activity. 相似文献
96.
97.
Shaimaa M. Aboukhatwa Dr. Thomas W. Hanigan Taha Y. Taha Dr. Jayaprakash Neerasa Dr. Rajeev Ranjan Dr. Eman E. El-Bastawissy Dr. Mohamed A. Elkersh Prof. Dr. Tarek F. El-Moselhy Prof. Dr. Jonna Frasor Prof. Dr. Nadim Mahmud Prof. Dr. Alan McLachlan Prof. Dr. Pavel A. Petukhov 《ChemMedChem》2019,14(11):1096-1107
Histone deacetylase (HDAC) activity is modulated in vivo by post-translational modifications and formation of multiprotein complexes. Novel chemical tools to study how these factors affect engagement of HDAC isoforms by HDAC inhibitors (HDACi) in cells and tissues are needed. In this study, a synthetic strategy to access chemically diverse photoreactive probes (PRPs) was developed and used to prepare seven novel HDAC PRPs 9 – 15 . The class I HDAC isoform engagement by PRPs was determined in biochemical assays and photolabeling experiments in live SET-2, HepG2, HuH7, and HEK293T cell lines and in mouse liver tissue. Unlike the HDAC protein abundance and biochemical activity against recombinant HDACs, the chemotype of the PRPs and the type of cells were key in defining the engagement of HDAC isoforms in live cells. Our findings suggest that engagement of HDAC isoforms by HDACi in vivo may be substantially modulated in a cell- and tissue-type-dependent manner. 相似文献
98.
99.
Youcef Djebloun Mabrouk Hecini Tarek Djoudi Belhi Guerira 《Journal of Natural Fibers》2019,16(3):357-367
The present study is an attempt to valorize local vegetable fibers by evaluating thire effectiveness as a new composite biomaterial. Our aim was to determine the mechanical characteristics, namely the elastic modulus and Poisson’s coefficient, of a fiber, locally called “Lif,” that is a natural material extracted from different date palm tree varieties in Biskra, a region situated in southeastern Algeria. This study compares the mechanical characteristcs of the Lif date palm tree fiber with other synthetic and plant fibers studied previously. 相似文献
100.
Hassan Ijaz Muhammad Zain-ul-abdein Waqas Saleem Muhammad Asad Tarek Mabrouki 《Machining Science and Technology》2018,22(3):522-542
Turning modeling and simulation of different metallic materials using the commercially available Finite Element (FE) softwares is getting prime importance because of saving of time and money in comparison to the costly experiments. Mostly, the numerical analysis of machining process considers a purely isotropic behavior of metallic materials; however, the literature shows that the elastic crystal anisotropy is present in most of the ‘so-called’ isotropic materials. In the present work, the elastic anisotropy is incorporated in the FE simulations along with the effect of grain size. A modified Johnson-Cook ductile material model based on coupled plasticity and damage evolution has been proposed to model the cutting process. The simulation results were compared with experimental data on the turning process of Aluminum alloy (AA2024). It was found that the elastic anisotropy influences the average cutting force up to 5% as compared to the isotropic models while the effect of grain size was more pronounced up to 20%. 相似文献