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901.
Annika Nebel Betreuer: Prof. Dr. Gerd Hamscher Prof. Dr. Dr. Reinhard B. Dettmeyer 《食品化学》2023,77(Z2):S2-033-S2-035
Gamma-Hydroxybutyrate (GHB) has been subject of scientific research due to its endogenous occurrence in humans and at the same time sedating effect after exogenous uptake, whether intentional or not. Of particular interest in this context is the distinction between possible endogenous GHB-concentrations and those that were in hair after a (single) exogenous uptake. In the present study, methods of extraction and quantification by LC-MS/MS for GHB and its metabolites glycolic acid, 2,4-dihydroxybutanoic acid (2,4-DHB), 3,4-dihydroxybutanoic acid (3,4-DHB) and 4-(sulfooxy)butanoic acid (GHB-sulf) were established. After validation of those methods, hair samples of persons without known exogenous GHB uptake were analysed to define an endogenous reference range for each substance. Subsequently hair samples were analysed after single or regular uptake of GHB. GHB-concentrations of 928 hair samples from persons without known uptake of GHB were between < 0.1 and 6.3 ng/mg. Only 29 samples showed concentrations higher than 3.0 ng/mg. Interestingly, hair samples that were stored for two to eight years showed significantly higher GHB-concentrations between 1.5 and 130 ng/mg, with 48 of 52 analysed segments showing concentrations above 3.0 ng/mg. Thus, storing seems to have a greater effect on the observed GHB-concentration than the quantity of GHB taken. In accordance with that, of 136 analysed hair samples of persons with a daily uptake of 3 to 9 g GHB, only 25 of the measured concentrations were above 3.0 ng/mg and only three outside of the prior defined endogenous reference range. The association between the quantity of exogenous GHB-uptake and the observed GHB-concentration in hair was found to be very weak. In agreement with those results, no raise in GHB-concentration was observed in hair samples after a single uptake of GHB. All concentrations were in the lower range of the prior defined endogenous reference range. Regarding the four analysed GHB-metabolites, the following endogenous reference ranges (including outliers) were defined: glycolic acid 0.39 - 11 (24) ng/mg, GHB-sulf < 0.40 - 1.7 (12) ng/mg, 3,4-DHB < 0.10 - 0.63 (4.7) ng/mg and 2,4-DHB < 0.20 - 0.45 (0.65) ng/mg. In hair samples from persons with regular uptake of GHB, at least one metabolite was found to be elevated (i.e., above the prior defined endogenous reference range) in the average of each hair strand, in contrast to the observed GHB-concentrations. In four of eleven hair strands even all four metabolites were above their endogenous reference range. Nevertheless, no statistically significant association between the quantity of GHB-uptake and the observed concentration in hair was found. Hair strands examined after a single GHB-uptake partially showed elevated concentrations of GHB-metabolites. The elevated segments, however, were not in each case those one would expect assuming the average hair growth rate of 1 cm/month. In the present study, it was shown that the exogenous uptake of GHB does not necessarily result in an elevated GHB-concentration in hair. Thus, the sole quantification of GHB will most likely not allow a clear decision whether or not GHB has been taken up exogenously. Thus, the here developed analytical methods do not yield legal certainty. However, in combination with the detection of one or more elevated GHB-metabolite concentrations, a better evaluation of this issue seems possible. 相似文献
902.
903.
Niklas Netsch Jonas Vogt Frank Richter Dr. Grazyna Straczewski Dr. Gerd Mannebach Dr. Volker Fraaije Dr. Salar Tavakkol Dr. Shahram Mihan Prof. Dr.-Ing. Dieter Stapf 《化学,工程师,技术》2023,95(8):1305-1313
Catalytic pyrolysis of post-industrial and post-consumer waste is studied in an auger-type reactor at pilot scale by applying two different zeolites and an amorphous silica-alumina catalyst in-situ at 400–550 °C. Contrary to thermal pyrolysis, of polyolefin-rich waste, high gaseous pyrolysis product yields of approx. 85 wt % are achieved with C2–C4 olefin contents of up to 67 wt %. After deactivation by coke deposition catalyst regeneration is proved feasible for maintaining the gaseous product yield and composition. Waste feedstocks with significant nitrogen and halogen heteroatom content are not suitable for in-situ catalytic pyrolysis. 相似文献
904.
Hexaazapolycycles by Selective Multimethylenations with Dichloromethane and Base or with Hexamethylenetetramine Multiple methylenations of 2-aminomethylbenzimidazole with dichloromethane and methylamine or ammonia or with hexamethylenetetramine lead to highly selective formations of 6 new single bonds to give only a polycyclic bis-spiro-1,5-diazocine 2 or only a polycyclic spiro-1,3,6-triazonine 4 or only a polycyclic 1,3,6,8-tetrazecine derivative 6 . 4 and 6 may be equally well obtained starting with 2-chloromethyl-benzimidazole. All of these selectively formed products are concave cryptands with 6 amino nitrogen atoms. No template metals are used in their syntheses. The reasons for the unusual changes in selectivity are investigated using semi-empirical PM3 calculations and mechanistic considerations. Experimental and spectroscopic details are given. 相似文献
905.
906.
Manfred Schulz Gerd West Reiner Radeglia 《Advanced Synthesis \u0026amp; Catalysis》1976,318(6):955-958
Photochemical Reactions of 3-Pyrazolidone Betains. VII. Photochemical Dimerization of 3-Pyrazolidone Azomethinimines UV irradiation of 3-pyrazolidone azomethinimines 1 in methanol results in low yields in photochemical head-tail-dimerization of 1 to the hexahydrotetrazines 3 . The structure of 3 is elucidated by chemical and spectroscopic methods (IR, 1H-, 13NMR). 相似文献
907.
Zeno Fldes-Papp Gerhard Gerber Reinhard Stsser Gerd Schneider 《Advanced Synthesis \u0026amp; Catalysis》1991,333(2):293-301
The decomposition of tert-butyl hydroperoxide by photochemically induced reactions in DMSO 1 Abbreviations used: DMSO, dimethyl sulfoxide; DMSO-d6, completely deuterium labelled dimethyl sulfoxide; cw-ESR, continuous-wave Electron Spin Resonance; u. v., ultra violet; DMPO, 5, 5-dimethyl-I-pyrroline N-oxide; TMPO, 3, 3, 5, 5-tetramethyl-l-pyrroline N-oxide. and water was investigated by cw-e.s.r. spectroscopy. The products tert-butylperoxyl, methyl and sulfur-centered free radicals were identified. The tert-butoxyl free radical is involved in the primary process as shown by time-resolved e.s.r. technique. On the basis of directly identified radical species, a mechanism for the photochemically induced reactions of tert-butyl hydroperoxide in DMSO is proposed. At concentrations below 0.8 mol · l−1 the radical formation from tert-butyl hydroperoxide proceeds by cleavage of the O O bond rather than by hydrogen abstraction. 相似文献
908.
909.
Dr. Paola Martinelli Dr. Otmar Schaaf Dr. Andreas Mantoulidis Dr. Laetitia J. Martin Dr. Julian E. Fuchs Dr. Gerd Bader Dr. Andreas Gollner Bernhard Wolkerstorfer Dr. Catherine Rogers Dr. Esra Balıkçı Dr. Jesse J. Lipp Dr. Nikolai Mischerikow Sandra Doebel Dr. Thomas Gerstberger Dr. Wolfgang Sommergruber Dr. Kilian V. M. Huber Dr. Jark Böttcher 《ChemMedChem》2023,18(6):e202200686
910.
Linda Schäker-Hübner Reza Haschemi Dr. Thomas Büch Fabian B. Kraft Birke Brumme Andrea Schöler Dr. Robert Jenke Prof. Dr. Jens Meiler Prof. Dr. Achim Aigner Prof. Dr. Gerd Bendas Prof. Dr. Finn K. Hansen 《ChemMedChem》2022,17(9):e202100755
Herein we report the structure-activity and structure-physicochemical property relationships of a series of class I selective ortho-aminoanilides targeting the “foot-pocket” in HDAC1&2. To balance the structural benefits and the physicochemical disadvantages of these substances, we started with a set of HDACi related to tacedinaline (CI-994) and evaluated their solubility, lipophilicity (log D7.4) and inhibition of selected HDAC isoforms. Subsequently, we selected the most promising “capless” HDACi and transferred its ZBG to our previously published scaffold featuring a peptoid-based cap group. The resulting hit compound 10 c ( LSH-A54) showed favorable physicochemical properties and is a potent, selective HDAC1/2 inhibitor. The following evaluation of its slow binding properties revealed that LSH-A54 binds tightly to HDAC1 in an induced-fit mechanism. The potent HDAC1/2 inhibitory properties were reflected by attenuated cell migration in a modified wound healing assay and reduced cell viability in a clonogenic survival assay in selected breast cancer cell lines. 相似文献