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11.
End-labeled free-solution electrophoresis of DNA 总被引:1,自引:0,他引:1
Meagher RJ Won JI McCormick LC Nedelcu S Bertrand MM Bertram JL Drouin G Barron AE Slater GW 《Electrophoresis》2005,26(2):331-350
DNA is a free-draining polymer. This subtle but "unfortunate" property of highly charged polyelectrolytes makes it impossible to separate nucleic acids by free-flow electrophoresis. This is why one must typically use a sieving matrix, such as a gel or an entangled polymer solution, in order to obtain some electrophoretic size separation. An alternative approach consists of breaking the charge to friction balance of free-draining DNA molecules. This can be achieved by labeling the DNA with a large, uncharged molecule (essentially a hydrodynamic parachute, which we also call a drag-tag) prior to electrophoresis; the resulting methodology is called end-labeled free-solution electrophoresis (ELFSE). In this article, we review the development of ELFSE over the last decade. In particular, we examine the theoretical concepts used to predict the ultimate performance of ELFSE for single-stranded (ssDNA) sequencing, the experimental results showing that ELFSE can indeed overcome the free-draining issue raised above, and the technological advances that are needed to speed the development of competitive ELFSE-based sequencing and separation technologies. Finally, we also review the reverse process, called free-solution conjugate electrophoresis (FSCE), wherein uncharged polymers of different sizes can be analyzed using a short DNA molecule as an electrophoretic engine. 相似文献
12.
[reaction: see text]. Commercially available cyanoethyl phosphoramidites derived from T, d(C), d(A), and d(G) were hydrolyzed (1H-tetrazole, MeCN/H2O) to give the corresponding H-phosphonates in excellent yields. Palladium(0)-catalyzed cross-coupling of each of these with the thymidine-derived vinylbromide 2 afforded the corresponding vinylphosphonate-linked dimers TT, d(C)T, d(A)T, and d(G)T in modest to good yields. The TT dimer was further elaborated to give a 5'-DMT-TT-3'-CEP building block, and this was used in the automated synthesis of the TpTTpT tetramer. 相似文献
13.
Summary This paper describes techniques for separation and purification of steroids on the thin-layer plate. Two or more operations can be performed on the same plate in order to avoid loss of material and product.When a steroid diketone (progesterone) is treated with 2,4-dinitrophenylhydrazine on silica gel, three products are obtainable. These compounds can be readily purified on the same thin-layer plate and converted to the parent steroid by means of stannous chloride in dilute hydrochloric acid.
Zusammenfassung Trennung und Reinigung von Steroiden auf der Dünnschichtplatte werden beschrieben. Zwei oder mehr Operationen lassen sich, um Substanzverluste zu vermeiden, auf derselben Platte ausführen.Wird ein Diketosteroid (Progesteron) mit 2,4-Dinitrophenylhydrazin auf Kieselgel behandelt, so erhält man drei Reaktionsprodukte, die auf derselben Platte leicht gereinigt und mit Zinn(II)-chlorid in verd. Salzsäure in das entsprechende Ausgangssteroid zurückverwandelt werden können.相似文献
14.
R. Bertram 《Fresenius' Journal of Analytical Chemistry》1966,222(2):189-200
Zusammenfassung Es wird über Aufbau und Leistungsfähigkeit eines neuen oscillometrischen Meßverfahrens zur Verfolgung von Reaktionsabläufen berichtet. Dabei befindet sich die mit dem Reaktionsgut gefüllte Meßzelle in einer speziellen Schaltstrecke, die so mit dem übrigen Schaltkreis gekoppelt ist, daß die sich einstellende Frequenz ein eindeutiges Maß für die in der Zelle ablaufenden Änderungen darstellt. Diese im Bereich zwischen 50 Hz und 1 MHz auftretenden Frequenzen werden mit Hilfe eines angepaßten Überlagerungsverfahrens mit hoher Empfindlichkeit zur Anzeige gebracht. Ein nachgeschalteter Schnellschreiber sorgt für eine momentane, lückenlose Registrierung. Das Verfahren ist im gesamten ionalen Leitfähigkeitsbereich sowohl für Zellen mit als auch ohne direkten Elektrodenkontakt verwendbar. Die Leistungsfähigkeit wird durch registrierte Meßkurven belegt. Unter anderem wurden schnellablaufende Verseifungsreaktionen von Trifluoressigsäurephenylester sowie langdauernde Adsorptionsvorgänge von Natronlauge an Quarzpulver untersucht. Schließlich wurde das Verfahren zur Aufzeichnung bislang unbekannter Auflösungsreaktionen von geschmolzenem Blei in einer Cadmiumchloridschmelze benutzt. Trotz der verzögerungsfreien Anzeige wird eine bisher von keiner Leitfähigkeitsmeßmethode erreichte Relativgenauigkeit von 10–3% gewährleistet.
Besonderer Dank gebührt der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie, die diese Arbeit durch Forschungsbeihilfen unterstützt haben. 相似文献
Summary In the field of oscillometry chemical reactions are recorded by means of measuring the electrical properties of the reaction medium. Thus, mainly changes in conductivity and dielectric constant are determined. In case of the method discussed the measuring cell filled with the reaction medium is placed in a special circuit, which is coupled with the main circuit in that way that the resulting frequency represents an unambiguous measure for the changes occurring in the cell. These frequencies in the range between 50 and 106 c/s are recorded with high sensitivity by means of an adapted heterodyne frequency method. The method is applicable in the whole ionic conductivity range for cells with and without direct electrode contact. The efficiency of the method is proved by measuring curves. For example, fast saponification reactions as well as long lasting adsorption reactions of NaOH on quartz powder were recorded. Also the method was applied to investigate the dissolution reactions of molten lead in molten cadmium chloride, that are not yet known. Although the reactions are recorded without delay, a relative accuracy of 10–3% is granted. This accuracy is not reached by any other conductivity method for the time being.
Besonderer Dank gebührt der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie, die diese Arbeit durch Forschungsbeihilfen unterstützt haben. 相似文献
15.
Bead cellulose derivatives as supports for immobilization and chromatographic purification of proteins 总被引:3,自引:0,他引:3
H F Boeden K Pommerening M Becker C Rupprich M Holtzhauer F Loth R Müller D Bertram 《Journal of chromatography. A》1991,552(1-2):389-414
Characteristic data are presented for Divicell, a macroporous bead cellulose with excellent flow parameters. The preparation of Divicell derivatives and their properties are described with respect to their application as chromatographic supports. The ion exchangers Divicell DEAE and Divicell CM were manufactured in two types with different exclusion limits and an available capacity for proteins of up to 100 mg/ml gel. Divicell Blue is a bead cellulose with covalently bound Cibacron Blue F3G-A and was found to be a very suitable adsorbent for the selective separation and purification of human serum albumin. Activation of Divicell with sodium periodate, epichlorohydrin and 5-norbornene-2,3-dicarboximido carbonochloridate provided activated supports used for immobilization of ligands in organic solvents and in aqueous solutions. Coupling of amines, diamines, amino acids, carbohydrates and proteins is described. The immobilized ligands retained their biological activity as determined by their specific adsorption of proteins. Divicell alkyl derivatives were tested in hydrophobic interaction chromatography with bovine serum albumin as a model. Examples are presented of the application of Divicell derivatives to the purification of biomacromolecules such as immunoglobulins and lectins by affinity chromatography. The results were comparable to those obtained using the corresponding Sepharose-derived absorbents. 相似文献
16.
17.
Ramona Hoffmann Bertram Taetz Markus Miezal Gabriele Bleser Sigrid Leyendecker 《PAMM》2016,16(1):89-90
This work investigates the combination of optical motion capturing data with optimal control simulations of human motion, which can be important in a wide range of applications in the professional as well as the private sector, ranging from health and ergonomics over human-machine-interaction to sports and games [1–3]. There are methodically very different approaches to include optical measurement data in the simulation of human motion, see e.g. [4–6]. Two different approaches to combine data and simulation are investigated in this work. Either we use a soft constraints approach, where the difference of simulated and measured marker positions is part of the objective function (1), or we formulate an hard constraints approach with nonlinear constraints that set an upper bound on this difference (2), while the objective function is purely physiologically motivated. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
19.
Abazov VM Abbott B Abdesselam A Abolins M Abramov V Acharya BS Adams DL Adams M Ahmed SN Alexeev GD Alves GA Amos N Anderson EW Arnoud Y Baarmand MM Babintsev VV Babukhadia L Bacon TC Baden A Baldin B Balm PW Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bauer D Bean A Beaudette F Begel M Belyaev A Beri SB Bernardi G Bertram I Besson A Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Blazey G Blessing S Boehnlein A Bojko NI Borcherding F Bos K Brandt A Breedon R 《Physical review letters》2002,88(17):171802
We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of pp events corresponding to 108.3 pb(-1) of data collected with the D0 detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, t-->b chi+1 and t-->blnu, no evidence for signal is found. We derive cross-section limits as a function of stop ( t ), chargino ( chi+1), and sneutrino ( nu) masses. 相似文献
20.
Bertram HC Rasmussen M Busk H Oksbjerg N Karlsson AH Andersen HJ 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,157(2):267-276
This study investigates the effects of developmental stage and muscle type on the mobility and distribution of water within skeletal muscles, using low-field (1)H-NMR transverse relaxation measurements in vitro on four different porcine muscles (M. longissimus dorsi, M. semitendinosus, M. biceps femoris, M. vastus intermedius) from a total of 48 pigs slaughtered at various weight classes between 25 kg and 150 kg. Principal component analysis (PCA) revealed effects of both slaughter weight and muscle type on the transverse relaxation decay. Independent of developmental stage and muscle type, distributed exponential analysis of the NMR T(2) relaxation data imparted the existence of three distinct water populations, T(2b), T(21), and T(22), with relaxation times of approximately 1-10, 45-120, and 200-500 ms, respectively. The most profound change during muscle growth was a shift toward faster relaxation in the intermediate time constant, T(21). It decreased by approx. 24% in all four muscle types during the period from 25 to 150 kg live weight. Determination of dry matter, fat, and protein content in the muscles showed that the changes in relaxation time of the intermediate time constant, T(21), during growth should be ascribed mainly to a change in protein content, as the protein content explained 77% of the variation in the T(21) time constant. Partial least squares (PLS) regression revealed validated correlations in the region of 0.58 to 0.77 between NMR transverse relaxation data and muscle development for all the four muscle types, which indicates that NMR relaxation measurements may be used in the prediction of muscle developmental stage. 相似文献