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排序方式: 共有409条查询结果,搜索用时 296 毫秒
101.
Daria Brambilla Cesare Mancuso Mariagrazia Rita Scuderi Paolo Bosco Giuseppina Cantarella Laurence Lempereur Giulia Di Benedetto Salvatore Pezzino Renato Bernardini 《Nutrition journal》2008,7(1):29
This review will discuss some issues related to the risk/benefit profile of the use of dietary antioxidants. Thus, recent
progress regarding the potential benefit of dietary antioxidants in the treatment of chronic diseases with a special focus
on immune system and neurodegenerative disorders will be discussed here. It is well established that reactive oxygen species
(ROS) play an important role in the etiology of numerous diseases, such as atherosclerosis, diabetes and cancer. Among the
physiological defense system of the cell, the relevance of antioxidant molecules, such as glutathione and vitamins is quite
well established. Recently, the interest of researchers has, for example, been conveyed on antioxidant enzyme systems, such
as the heme oxygenase/biliverdin reductase system, which appears modulated by dietary antioxidant molecules, including polyphenols
and beta-carotene. These systems possibly counteract oxidative damage very efficiently and finally modulate the activity of
oxidative phenomena occurring, for instance, during pathophysiological processes. Although evidence shows that antioxidant
treatment results in cytoprotection, the potential clinical benefit deriving from both nutritional and supplemental antioxidants
is still under wide debate. In this line, the inappropriate assumption of some lipophylic vitamins has been associated with
increased incidence of cancer rather than with beneficial effects. 相似文献
102.
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104.
Ilenia Rossetti Cesare Biffi Gian Franco Tantardini Mario Raimondi Edoardo Vitto Davide Alberti 《International Journal of Hydrogen Energy》2012
A power unit constituted by a reformer section, a H2 purification section and a fuel cell stack is being tested c/o the Dept. of Physical Chemistry and Electrochemistry of Università degli Studi di Milano, on the basis of a collaboration with HELBIO S.A. Hydrogen and Energy Production Systems, Patras (Greece), supplier of the unit, and some sponsors (Linea Energia S.p.A., Parco Tecnologico Padano and Provincia di Lodi, Italy). The system size allows to co-generate 5 kWe (220 V, 50 Hz a.c.) + 5 kWt (hot water at 65 °C) as peak output. Bioethanol, obtainable by different non-food-competitive biomass, is transformed into syngas by a pre-reforming and reforming reactors couple and the reformate is purified from CO to a concentration below 20 ppmv, suitable to feed a proton exchange membrane fuel cell (PEMFC) stack that will be integrated in the fuel processor in a second step of the experimentation. This result is achieved by feeding the reformate to two water gas shift reactors, connected in series and operating at high and low temperature, respectively. CO concentration in the outcoming gas is ca. 0.4 vol% and the final CO removal to meet the specifications is accomplished by two methanation reactors in series. The second methanation step acts merely as a guard, since ca. 15 ppmv of CO are obtained already after the first reactor. 相似文献
105.
Mauro Vasconi Fabio Caprino Federica Bellagamba Maria Letizia Busetto Cristian Bernardi Cesare Puzzi Vittorio Maria Moretti 《Lipids》2015,50(3):283-302
In this study, the proximate and fatty acid compositions of the muscle tissue of 186 samples of fish belonging to fifteen species of freshwater fish harvested in subalpine lakes (bleak, shad, crucian carp, whitefish, common carp, pike, black bullhead, burbot, perch, Italian roach, roach, rudd, wels catfish, chub and tench) were investigated. Most of the fish demonstrated a lipid content in the fillet lower than 2.0 g 100 g?1 wet weight (range 0.6–9.7). A strong relationship between feeding behavior and fatty acid composition of the muscle lipids was observed. Planktivorous fish showed the lowest amounts of n‐3 fatty acids (p < 0.05), but the highest monounsaturated fatty acid (MUFA) contents, in particular 18:1n‐9. Conversely, carnivorous fish showed the highest amounts of saturated fatty acids and n‐3 fatty acids (p < 0.05), but the lowest MUFA contents. Omnivorous fish showed substantial proportions of n‐3 fatty acids and the highest contents of n‐6 fatty acids. Principal component analysis showed a distinct separation between fish species according to their feeding habits and demonstrated that the most contributing trophic markers were 18:1n‐9, 18:3n‐3, 22:6n‐3 and 20:4n‐6. The quantitative amounts n‐3 polyunsaturated fatty acid in muscle tissues varied depending on the fish species, the lipid content and the feeding habits. Some species were very lean, and therefore would be poor choices for human consumption to meet dietary n‐3 fatty acid requirements. Nevertheless, the more frequently consumed and appreciated fish, shad and whitefish, had EPA and DHA contents in the range 900–1,000 mg 100 g?1 fresh fillet. 相似文献
106.
Prudenzano F Mescia L Palmisano T Surico M De Sario M Righini GC 《Applied optics》2012,51(9):1420-1430
Different strategies for designing optical couplers, optimized to enhance the pump absorption in the rare-earth-doped core of microstructured fiber lasers, are illustrated. Three kinds/configurations of optical couplers have been designed and compared as examples of the different design strategies which can be followed. Their effectiveness to enhance the performance of an ytterbium-doped, double cladding, microstructured optical fiber laser has been accurately simulated. They consist of a suitable cascade of multiple long-period gratings (MLPGs) inscribed in the fiber core region. The characteristics of the MLPG couplers have been simulated via a homemade computer code based on both rate equations and an extended coupled mode theory. The proposed MLPG couplers seem particularly useful in the case of low rare-earth concentration but, even for a middle-high ytterbium concentration, as N(Yb)=5×10(25) ions/m(3), the slope efficiency S can be increased up to 20%, depending on the fiber length. 相似文献
107.
In vitro fertilisation with frozen-thawed bovine sperm sexed by flow cytometry and validated for accuracy by real-time PCR 总被引:1,自引:0,他引:1
Puglisi R Vanni R Galli A Balduzzi D Parati K Bongioni G Crotti G Duchi R Galli C Lazzari G Aleandri R 《Reproduction (Cambridge, England)》2006,132(3):519-526
The methodologies used for cytometric sorting of fresh spermatozoa never allowed a clear resolution of sexual chromosomes of frozen-thawed semen. To devise a novel method for the production of bovine predefined sexed embryos using frozen-thawed semen, sorting efficiency of different protocols was studied using a new quantitative real-time PCR method to verify the purity of sexed semen. To this aim, after Percoll separation, frozen-thawed samples were stained at different temperatures and concentrations of Hoechst 33342 using a short-incubation time. The concentration of Hoechst 33342 of 500 mug/ml at a temperature of 37 degrees C provided good and stable fluorescence signals. Preventing the sperm clustering by adding 0.6% BSA in the 90% Percoll fraction led to X-bearing sperms purity of 91+/-2%. Thereafter, sorted sperms were used for in vitro fertilisation (IVF). Despite the lower cleavage rates reported in the sorted groups when compared with the control groups (40 vs 48%, P<0.01), blastocyst formation in the sorted and control groups was not different (27 vs 24% of the cleaved respectively). The PCR analysis of 30 blastocysts confirmed 26 embryos to be correctly sexed (87%). Transfer of two embryos per recipient into six synchronised heifers resulted in four pregnancies. Two abortions occurred at day 60, while two pregnancies went to term delivering two female calves. In conclusion, high purity and repeatability of sorting was obtained with frozen-thawed bull semen that was subsequently used for IVF giving rise to viable embryos and offspring. In addition, real-time PCR revealed to be an optimal support for these studies, providing a rapid and reliable estimation of flow cytometric efficiency. 相似文献
108.
Giampaolo E. DErrico 《Measurement》2009,42(10):1478-1481
Null Hypothesis Significance Testing (NHST) is a well known tool in statistical inference. NHST has a wide potential applicability in experimental research, for instance in treatment of outlying observations. However, rational of NHST and inter-pretations of results of significance tests are debated. In the present paper, principles and applications of NHST are presented and discussed in the framework of Bayesian statistics, focusing on perspectives of metrological interest. 相似文献
109.
Impact of Turbidity Currents on Reservoir Sedimentation 总被引:4,自引:0,他引:4
All lakes created on natural rivers are subjected to reservoir sedimentation. The construction of a dam significantly modifies the flow conditions of natural streams inside and downstream of an artificial lake. The sediment concentration is often high during the flood season, and the entering flow shows a greater density than the ambient fluid. Suspended load can therefore be carried along the reservoir bottom to the dam in the form of turbidity currents. This paper presents research results that help to better understand this physical phenomenon, which contributes to reservoir sedimentation. It is based on in situ measurements, a laboratory scale model of turbidity currents and numerical flow simulations. The study of a thousand-year flood in the Luzzone Reservoir in the Swiss Alps using the developed computer model revealed the potential of such a tool. In particular, the impact on the sediment deposits was analyzed. A valuable evaluation of the incidence of such a turbidity flow is presented and its effects are compared to observations. Significant progress has been made in understanding the importance of turbidity currents in reservoir sedimentation. 相似文献
110.
Elena Vismara Lucio Melone Giuseppe Gastaldi Cesare Cosentino Giangiacomo Torri 《Journal of hazardous materials》2009,170(2-3):798-808
Cellulose material C1 was prepared by grafting of glycidyl methacrylate (GMA) in the presence of Fenton-type reagent. This one-pot procedure provided C1 with glycidyl isobutyrate branches. Glycidyl epoxide ring opening with water turned C1–C2 material branched with glycerol isobutyrate. So, C1 surface bears hydrophobic branches ending with the glycidyl group, while C2 surface presents hydrophilic branches ending with the glycerol group. The adsorption of aromatic polluting substances like phenol (Ph), 4-nitrophenol (pNPh), 2,4-dinitrophenol (dNPh), 2,4,6-trinitrophenol (picric acid, tNPh) and 2-naphtol (BN) from their water solutions was tested with C1, C2 and with the untreated cellulose material C0. Phenol adsorption did not occur. All the other aromatic molecules were removed in different amount both by C1 and C2. C1 and C2 showed different affinities towards nitrophenols and 2-naphtol. While C1 was much more effective for removing the hydrophobic 2-naphtol, C2 had higher adsorption capacity towards the hydrophilic nitrophenols, in agreement with their branches polarity, respectively. 相似文献