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排序方式: 共有1041条查询结果,搜索用时 15 毫秒
991.
Zusammenfassung Frische Moosbeeren, die im Laufe der Monate November 1931–Februar 1932 untersucht wurden, zeigten durchschnittlich eine antiskorbutische Aktivität, die zwischen 100 und 200 Einheiten in 1 Liter Saft oder 80–160 Einheiten in 1 kg Produkt liegt. Es wurde kein Unterschied in der antiskorbutischen Wirkung des Saftes und der Moosbeeren—in Mengen, die dem Safte entsprechen—gefunden.bedeutet mit Abbildungen. 相似文献
992.
Inflammatory processes are involved in the etiology of diseases. We analyzed the effect of resveratrol, piceatannol, synthetic tri-acetoxystilbene (TAS), and genistein (Bonistein(TM)) on the production of inflammatory mediators including prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha), interleukins, and chemokines, which participate in the progression of inflammation. In order to induce inflammatory responses, human peripheral blood mononuclear and/or polymorphonuclear leukocytes were stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN(gamma)) and the production of PGE2, interleukin-8 (IL-8), and TNF-alpha was determined. In response to the stimuli, genes were substantially activated within < 2 h (e. g., TNF-alpha, IL-1alpha), or at a later stage, (e. g., COX-2, IL-6, IL-8). Unlike genistein, resveratrol and related compounds dose-dependently reduced PGE2 production. Genistein, piceatannol, and TAS diminished secretion of TNF-alpha, and IL-8. TAS reduced mRNA levels of COX-2, TNF-alpha, IL-8, IL-6, and IL-1alpha, while resveratrol impaired early expression of IL-8 and TNF-alpha. Piceatannol out-performed resveratrol, yet without matching TAS. Genistein downregulated TNF-alpha and IL-8 expression. These substances altered the LPS/IFNgamma-induced gene expression in mononuclear cells rather than in polymorphonuclear leukocytes. Immunoblot analyses corroborated the distinct activity pattern of resveratrol and genistein. In conclusion, resveratrol and their derivatives attenuated the inflammatory response of PBLs at several levels, whereas genistein acts on cytokines and pro-inflammatory interleukins. 相似文献
993.
Yu Y Ding C Wang E Chen X Li X Zhao C Fan Y Wang L Beaujean N Zhou Q Jouneau A Ji W 《Reproduction (Cambridge, England)》2007,133(5):947-954
Even though it generates healthy adults, nuclear transfer in mammals remains an inefficient process. Mainly attributed to abnormal reprograming of the donor chromatin, this inefficiency may also be caused at least partly by a specific effect of the cloning technique which has not yet been well investigated. There are two main procedures for transferring nuclei into enucleated oocytes: fusion and piezoelectric microinjection, the latter being used mostly in mice. We have, therefore, decided to compare the quality and the developmental ability, both in vivo and in vitro, of embryos reconstructed with electrofusion or piezoelectric injection. In addition, the effect of piezo setups of differing electric strengths was investigated. Along with the record of the rate of development, we compared the nuclear integrity in the blastomeres during the first cleavages as well as the morphological and cellular quality of the blastocysts. Our results show that the piezo-assisted micromanipulation can induce DNA damage in the reconstructed embryos, apoptosis, and reduced cell numbers in blastocysts as well as a lower rate of development to term. Even if piezo-driven injection facilitates a faster and more efficient rate of reconstruction, it should be used with precaution and with as low parameters as possible. 相似文献
994.
Maha Mezghani-Khemakhem Dhia Bouktila Nathalie Casse Houcine Maaroufi Mohamed Makni Hanem Makni 《International journal of molecular sciences》2012,13(11):14446-14450
Using an enriched library method, seven polymorphic microsatellite loci were isolated from the barley stem gall midge, Mayetiola hordei. Polymorphism at loci was surveyed on 57 individual midges collected on barley in Tunisia. Across loci, polymorphism ranged from two to six alleles per locus. The observed heterozygosity varied between 0.070 and 0.877. Based on the number of alleles detected and the associated levels of heterozygosity, we believe that these loci will prove useful for population genetic studies on M. hordei. 相似文献
995.
Nathalie De Clercq Sabine Danthine Mai Tuyet Nguyen Veronique Gibon Koen Dewettinck 《Journal of the American Oil Chemists' Society》2012,89(2):219-229
Interesterification is an important modification technique for fats and oils resulting in the redistribution of the fatty
acids among the glycerol backbone and thus changing the physico-chemical properties of the modified fat. In this study palm
oil, palm olein and soft palm mid fraction (PMF) were subjected to both enzymatic (batchwise) and chemical interesterification.
The reaction products were characterized before, during and after interesterification by HPLC, pulsed NMR (p-NMR) and differential
scanning calorimetry (DSC). Interesterification led to more uniform triacylglycerol (TAG) compositions with smaller differences
in final physico-chemical properties between the studied substrates. The degree of interesterification was evaluated on the
basis of TAG composition and solid fat content (SFC). Significant differences between both methods were observed. The degree
of interesterification based on SFC is therefore a better tool to evaluate the rate constant of the reaction as the TAG composition
method does not take into consideration the formation of positional isomers at the end of the enzymatic process. 相似文献
996.
Electroleaching and electrodeposition of zinc in a single-cell process for the treatment of solid waste 总被引:2,自引:1,他引:1
This work deals with zinc beneficiation of industrial solid waste by an electrochemical technique combining electroleaching and electrodeposition in a single-cell process. This technique is based on leaching of the solid waste by the protons generated at the anode and migration of the resulting ions toward the cathode where deposition takes place. A laboratory cell was built for testing the method. It consisted of three compartments, two electrode compartments and a solid waste chamber placed between these. Catholyte and anolyte were sulphuric/sulphate solutions at optimised concentrations. Experiments were first carried out using a zinc solution and an inert matrix in the central compartment, then using a synthetic waste prepared by dispersing zinc oxide in silicon dioxide. Best performance was obtained with treatment duration of 6h, at 4.5Adm(-2) and with catholyte circulation. In this case, a 97% of zinc oxide lixiviation and 75% of zinc-plated were achieved. 相似文献
997.
998.
Marie B Luquet G Bédouet L Milet C Guichard N Medakovic D Marin F 《Chembiochem : a European journal of chemical biology》2008,9(15):2515-2523
The formation of the molluscan shell is finely tuned by macromolecules of the shell organic matrix. Previous results have shown that the acid-soluble fraction of the nacre matrix of the freshwater paleoheterodont bivalve Unio pictorum shell displays a number of remarkable properties, such as calcium-binding activity, the presence of extensive glycosylations and the capacity to interfere at low concentration with in vitro calcium carbonate precipitation. Here we have found that the nacre-soluble matrix exhibits a carbonic anhydrase activity, an important function in calcification processes. This matrix is composed of three main proteinaceous discrete fractions. The one with the highest apparent molecular weight is a 95 kDa glycoprotein that is specific to the nacreous layer. P95, as it is provisionally named, is enriched in Gly, Glx and Asx and exhibits an apparent pI value of approximately 4, or approximately 7 when chemically deglycosylated. Furthermore, its glycosyl moiety, consisting of sulfated polysaccharides, is involved in calcium binding. Purified fractions of the three main proteins were digested with trypsin, and the resulting peptides were analysed by mass spectrometry. Our results suggest that identical peptides are constitutive domains of the different proteins. Partial primary structures were obtained by de novo sequencing and compared with known sequences from other mollusc shell proteins. Our results are discussed from an evolutionary viewpoint. 相似文献
999.
Nathalie Di Miceli Raimondi Christophe Gourdon Patrick Cognet 《Chemical engineering science》2008,63(22):5522-5530
Microreactors for the development of liquid-liquid processes are promising technologies since they are supposed to offer an enhancement of mass transfer compared to conventional devices due to the increase in the surface/volume ratio. But impact of the laminar flow should be negative and the effect is still to be evaluated. The present work focuses on the study of mass transfer in microchannels by means of 2D direct numerical simulations. We investigated liquid-liquid slug flow systems in square channel of depth. The droplet velocity ranges from 0.0015-0.25 m/s and the ratio between the channel depth and the droplet length varies between 0.4 and 11.2. Droplet side volumetric mass transfer coefficients were identified from concentration field computations and the evolution of these coefficients as a function of the flow parameters and the channel size is discussed. This study reveals that mass transfer is strongly influenced by the flow structure inside the droplet. Moreover, it shows that the confinement of the droplets due to the channel size leads to an enhancement of mass transfer compared to cases where the droplets are not constrained by the walls. 相似文献
1000.
This paper describes successful electrodeposition of very homogeneous, adherent and well-crystallized thin layers of birnessite on a cheap transparent semiconductor substrate, SnO2, in neutral sulphate solutions. Birnessite, a layered manganese oxide, plays an important role in environmental chemistry due to its large surface area. A coupled approach based on electrochemical measurements and pH measurements allowed us to give information about electrodeposition mechanism of birnessite. An intermediary Mn(III) compound, α-MnOOH (groutite), is formed in deaerated solutions leading to mixed thin layers of birnessite and groutite. But, thin layers of pure birnessite can be efficiently electrodeposited in aerated solutions due to the oxidation of groutite by dissolved oxygen in such solutions. Thin layers of pure birnessite are well suitable for studies devoted to environmental applications as hazardous waste remediation or chemical sensors but also as electrode material for energy storage. 相似文献