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排序方式: 共有343条查询结果,搜索用时 15 毫秒
111.
Hrvoje Juretić Slaven Dobrović Nikola Ružinski Josip Lovrić Marijana Pećarević Josip Mikuš 《臭氧:科学与工程》2011,33(1):3-13
A pilot-plant study was conducted in the Republic of Croatia to determine the applicability of ozonation for inactivation of non-indigenous species and to provide necessary information regarding use of ozone as a ballast water treatment option. Nauplii of the brine shrimp Artemia salina were used as model organisms to investigate the efficacy of ozonation at three different ozone dosages (2.4, 3.7 and 10.9 mg L?1). Mortality of Artemia nauplii at 98.6%, was achieved after 3 h of exposure in ozone-treated water with the highest ozone dosage. Our results indicated that ozonation is a promising treatment for controlling non-indigenous and potentially invasive species; however, to draw more general conclusions, several species with higher level of resistance to ozone are required and will be studied in the future. 相似文献
112.
Petr Mlejnek Petr Dolezel Eva Kriegova Nikola Pastvova 《International journal of molecular sciences》2021,22(23)
N-acetylcysteine (NAC), often used as an antioxidant-scavenging reactive oxygen species (ROS) in vitro, was recently shown to increase the cytotoxicity of other compounds through ROS-dependent and ROS-independent mechanisms. In this study, NAC itself was found to induce extensive ROS production in human leukemia HL-60 and U937 cells. The cytotoxicity depends on ROS-modulating enzyme expression. In HL-60 cells, NAC activated NOX2 to produce superoxide (O2•−). Its subsequent conversion into H2O2 by superoxide dismutase 1 and 3 (SOD1, SOD3) and production of ClO− from H2O2 by myeloperoxidase (MPO) was necessary for cell death induction. While the addition of extracellular SOD potentiated NAC-induced cell death, extracellular catalase (CAT) prevented cell death in HL-60 cells. The MPO inhibitor partially reduced the number of dying HL-60 cells. In U937 cells, the weak cytotoxicity of NAC is probably caused by lower expression of NOX2, SOD1, SOD3, and by the absence of MOP expression. However, even here, the addition of extracellular SOD induced cell death in U937 cells, and this effect could be reversed by extracellular CAT. NAC-induced cell death exhibited predominantly apoptotic features in both cell lines. Conclusions: NAC itself can induce extensive production of O2•− in HL-60 and U937 cell lines. The fate of the cells then depends on the expression of enzymes that control the formation and conversion of ROS: NOX, SOD, and MPO. The mode of cell death in response to NAC treatment bears apoptotic and apoptotic-like features in both cell lines. 相似文献
113.
Recent interest in natural refrigerants has created a new impetus for studies of CO2 as a working fluid in vapour compression systems for refrigeration and air conditioning. Two major drawbacks to its use are the very high pressure differences required across the compressor and the large efficiency losses associated with the throttling process in the refrigeration cycle. It is shown how these disadvantages can be minimised by the use of a screw machine both to compress the gas and use the expansion process to recover power. Both these functions can be performed simultaneously, using only one pair of rotors, in a configuration that partially balances out the forces induced by the pressure difference and hence, reduces the bearing loads to an acceptable level. A further feature is the use of rotors, which seal on both contacting surfaces so that the same profile may be used for the expander and the compressor sections. This enables the rotors performing both these functions to be machined or ground in the same cutting operation and then separated by machining a parting slot in them. Computational Continuum Mechanics comprising both, fluid flow and structural analysis is used in this paper for the investigation of fluid-solid interaction in such machines. 相似文献
114.
Nikola Segudovic Radivoje Vukovic Vjera Kuresevic Frank E. Karasz William J. Macknight 《Polymer International》1993,31(2):197-205
The weight-average molecular weights (M?w) of nominally random, unfractionated copolymers of ortho- and para-fluorostyrene and ortho- and para-chlorostyrene were determined by light scattering measurements in tetrahydro-furan, toluene, carbon tetrachloride and chloroform. It was shown that there is no significant variation in measured M?w in the various solvents, a finding indicating that the copolymers are not compositionally heterogeneous. Intrinsic viscosity measurements in the same solvents established a consistent relationship between [n] and M?w despite the differences in copolymer compositions. It was not possible to establish a similar relationship between the second virial coefficient A2 and M?w. It was concluded that measurements of the specific refractive index increment could be used for determining copolymer composition if the measurements were performed in thermodynamically poorer solvents. The results established for the Mark-Houwink constant α, intrinsic viscosity, and A2 values indicated that these solvated copolymer molecules are in a less expanded conformation than are polystyrene molecules of similar molecular weights in a given solvent. 相似文献
115.
The crystallization and hydrogen desorption of pre-charged amorphous Cu33Ti67 alloy have been studied by differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). The effect of the SEM electron beam on the desorption process was analyzed. It was found that small amounts of absorbed hydrogen do not influence on the thermal stability of the glass, but significantly reduce its crystallization enthalpy. At higher hydrogen concentrations the thermal stability of the glass was strongly reduced (with about 250 K), as the low-temperature crystallization product was mainly extremely fine nanocrystalline Cu2Ti, formed as a result of the Cu enrichment of the amorphous phase after hydriding. Combining DSC, TG and SEM it was proved that during the electron beam exposure the weaker bonded hydrogen, which desorbs thermally at 430–500 K, releases. Annealing at higher temperatures (> 500 K) showed clearly the existence of nanocrystalline Cu2Ti and TiH2 phases. Only after the TiH2 decomposition (at ~ 680 K) the equilibrium crystalline phase (Ti2Cu) was formed, but with finer microstructure. 相似文献
116.
Shaoning Pang Ilkka Havukkala Yingjie Hu Nikola Kasabov 《Neural computing & applications》2007,16(6):527-539
Consistency modelling for gene selection is a new topic emerging from recent cancer bioinformatics research. The result of
operations such as classification, clustering, or gene selection on a training set is often found to be very different from
the same operations on a testing set, presenting a serious consistency problem. In practice, the inconsistency of microarray
datasets prevents many typical gene selection methods working properly for cancer diagnosis and prognosis. In an attempt to
deal with this problem, this paper proposes a new concept of classification consistency and applies it for microarray gene
selection problem using a bootstrapping approach, with encouraging results. 相似文献
117.
Rezensionen
Nikola Biller-Andorno (2001) Gerechtigkeit und Fürsorge. Zur Möglichkeit einer integrativen MedizinethikKultur der Medizin, Bd. 2; zugl.: Göttingen, Habilschrift, 2000; Campus, Frankfurt, New York, 196 S., ISBN 3-593-36854-4, Euro 29,90 相似文献118.
Mohan D Pasa-Tolić L Masselon CD Tolić N Bogdanov B Hixson KK Smith RD Lee CS 《Analytical chemistry》2003,75(17):4432-4440
This work focuses on the development of a multidimensional electrokinetic-based separation/concentration platform coupled with electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) for achieving the high resolution and ultrasensitive analysis of complex protein/peptide mixtures. A microdialysis junction is employed as the interface for on-line combination of capillary isoelectric focusing (CIEF) with transient capillary isotachophoresis/zone electrophoresis (CITP/CZE) in an integrated platform. Besides the excellent resolving power afforded by both CIEF and CZE separations, the electrokinetic focusing/stacking effects of CIEF and CITP greatly enhance the dynamic range and detection sensitivity of MS for protein identification. The constructed multidimensional separation/concentration platform is demonstrated for the analysis of Shewanella oneidensis proteome, which has considerable implications toward the bioremediation of environmental pollutants. The electrokinetic-based platform offers the overall peak capacity comparable to those obtained using multidimensional chromatography systems, but with a much shorter run time and no need for column regeneration. Most importantly, a total of 1174 unique proteins, corresponding to 26.5% proteome coverage, are identified from the cytosolic fraction of S. oneidensis, while requiring <500 ng of proteolytic digest loaded in the CIEF capillary. The ultrasensitive capabilities of electrokinetic-based proteome approach are attributed to the concentration effect in CIEF, the electrokinetic stacking of CITP, the nanoscale peak volume in CZE, the "accurate mass tag" strategy for protein/peptide identification, and the high-sensitivity, high-resolution, and high-mass measurement accuracy of FTICR-MS. 相似文献
119.
Nikola Drenchev Tony Spassov Stoyan Bliznakov 《Journal of Alloys and Compounds》2008,450(1-2):288-292
Mg2−xSnxNi (x = 0, 0.1, 0.3) alloys were synthesized by reactive ball milling under protective Ar atmosphere and liquid n-heptane. The microstructure and the morphology of the powders were determined by X-ray diffraction and scanning electron microscopy. The as-milled alloys consist of Mg2Ni nanocrystals with an average grain size in the range 3–7 nm, depending on the alloy composition. Sn containing phases were not detected even in the Sn-rich alloy. Obviously, Sn is dissolved in the Mg2Ni intermetallic compound. Gas phase sorption of hydrogen was not observed in the alloys containing Sn (Mg2−xSnxNi; x = 0.1, 0.3). It was suggested that Sn impedes the process of hydrogen molecules decomposition. The as-milled alloys absorbed reversibly hydrogen electrochemically. Mg2Ni alloy showed the highest discharge capacity of 300 mAh/g. The capacity of Mg1.9Sn0.1Ni and Mg1.7Sn0.3Ni was about 260 mAh/g. It was found that Sn improved the cycle life of the electrode. 相似文献
120.
Clean Technologies and Environmental Policy - The paper shows the process of the development of the sustainable energy action plan (SEAP) for the city of Zagreb and analysis of the interaction... 相似文献