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101.
In the presence of a stabilising colloid Malachite Green and phosphododekamolybdate acid form a dyestuff salt. When the excess of the Malachite Green has reacted in acid solution to colourless products, the remaining colour is a measure for the phosphate quantity. The method permits the determination of 10–1200 μg of phosphate/l.  相似文献   
102.
Zusammenfassung Mit Hilfe des Weissenberg-Rheogoniometers wurden an 107 pathologischen Kniegelenkspunktaten (47 nicht entzündliche, 60 entzündliche) das viskose Fließverhalten, Normalkräfte und anhand von Anlaufmessungen ein Schermodul zur Berechnung der Anzahl molekularer Verhängungen bestimmt. Viskoses und elastisches Verhalten der entzündlichen Gelenkergüsse unterscheiden sich zwar deutlich von dem der nichtentzündlichen Ergüsse, die hohe Streuung der Werte weist jedoch darauf hin, daß verschiedene pathogenetische Vorgänge zu den gleichen rheologischen Eigenschaften der Synovia führen können. Daher ist der differentialdiagnostische Aussagewert der rheologischen Untersuchungsergebnisse gering.Hyaluronsäure-Konzentrationsänderungen sind nur zum Teil für die pathologische Rheologie der Synovia verantwortlich. Die Anwendung einer Normierungsmethode auf die Viskosität der Synovia läßt Unterschiede im Polymerisationsgrad der Hyaluronsäure in entzündlichen und nicht entzündlichen Ergüssen erkennen.
Summary In 107 pathological synovial fluid samples of knee joints (47 non-inflammatory, 60 inflammatory) the Weissenberg-Rheogoniometer is used for measurements of viscosity, normal force and a shear modulus obtained by prestationary measurements to calculate the number of molecular entanglements.Viscosity and elasticity of the inflammatory synovial fluids are clearly different from the non-inflammatory group, but the high scattering of the values shows that various pathological conditions lead to the same rheological properties of the synovial fluid. Therefore the rheological results have little diagnostic signification.Variation of the hyaluronic acid concentrations are responsible only in part for the pathological synovial fluid rheology. A normalization method for the synovial fluid viscosity suggests differences in the polymerisation of the hyaluronic acid in inflammatory and non-inflammatory synovial fluids.


Mit 6 Abbildungen und 1 Tabelle  相似文献   
103.
The analysis of polyphenols from solid plant or food samples usually requires laborious sample preparation. The liquid extraction of these compounds from the sample is compromised by apolar matrix interferences, an excess of which has to be eliminated prior to subsequent purification and separation. Applying pressurized liquid extraction to the extraction of polyphenols from hops, the use of different solvents sequentially can partly overcome these problems. Initial extraction with pentane eliminates hydrophobic compounds like hop resins and oils and enables the straightforward automated on-line solid-phase extraction as part of an optimized LC-MS analysis.  相似文献   
104.
Angle-resolved photoemission is used to determine the change in the electronic states of Ni induced by doping with Fe and Cr. Well-defined spin and k states are selected using high energy and k resolution combined with single crystal alloys. Iron suppresses the mean free path of minority spins only, while chromium suppresses both spins and decreases the magnetic splitting. The strong variation of these effects from one impurity to the other supports the concept of magnetic doping.  相似文献   
105.
106.
The word-stock of a language is a complex dynamical system in which words can be created, evolve, and become extinct. Even more dynamic are the short-term fluctuations in word usage by individuals in a population. Building on the recent demonstration that word niche is a strong determinant of future rise or fall in word frequency, here we introduce a model that allows us to distinguish persistent from temporary increases in frequency. Our model is illustrated using a 108-word database from an online discussion group and a 1011-word collection of digitized books. The model reveals a strong relation between changes in word dissemination and changes in frequency. Aside from their implications for short-term word frequency dynamics, these observations are potentially important for language evolution as new words must survive in the short term in order to survive in the long term.  相似文献   
107.
A new convergent total synthesis of the marine macrolide mandelalide A ( 1 ) has been developed that is based on macrocyclic ring closure by a Shiina‐type macrolactonization and the construction of the requisite precursor seco acid by a highly efficient Sonogashira cross‐coupling reaction between two fragments of comparable complexity. Key steps in the elaboration of the acid building block were the enantioselective, catalytic addition of a protected acetylene to crotonaldehyde and the construction of the tetrahydropyran unit that is embedded in the macrocycle by means of an acid‐catalyzed Prins reaction. The synthesis of the alcohol fragment features the formation of the trisubstituted tetrahydrofuran ring through an acetal cleavage/epoxide opening cascade reaction and a rarely used radical alkynylation of a primary alkyl iodide. Intriguingly, the dihydroxylation of a terminal double bond as part of the synthesis of this building block gave the same major product for both the α‐ and β‐AD‐mix reagents, albeit with moderate or low selectivity. Synthetic mandelalide A ( 1 ) was a potent proliferation inhibitor of A549, HT460, and H1299 human lung cancer cells in vitro, but not of SK‐N‐SH neuroblastoma cells. However, in no case did we observe complete cell kill even at the highest compound concentration tested (5 μm ).  相似文献   
108.
Abstract

The photoinduced cationic crosslinking of α, ω-terminated disiloxanes (epoxy, vinyl ether, propenyl ether) has been investigated by means of Real-Time IR spectroscopy. A lipophilic iodonium salt and three lipophilic sulfonium salts were used as photoinitiator. The crosslinking rate is influenced by the type of α, ω-terminated disiloxane used and differed by a factor of more than 100 from the aliphatic epoxy to the vinyl ether derivatives. Moreover, the sulfonium salts were found to have a lower initiation efficiency than the lipophilic iodonium salt in the various systems studied. These results are in good agreement with the quantum yield of proton formation in a hexamethyldisiloxane/dimethoxyethane mixture. The final degree of conversion is larger with the ene derivatives than with the epoxy derivatives. The application of a kinetic method allows us to estimate the rate constant of the termination step (kt and for the propenyl derivative the rate constant of the propagation step kp. The termination step can be described by means of a first order reaction. kt was found to depend on the light intensity and the type of initiators used, whereas kp is independent of the initiator used.  相似文献   
109.
Porous polymer membranes made via electrostatic complexation are fabricated from a water‐soluble poly(ionic liquid) (PIL) for the first time. The porous structure is formed as a consequence of simultaneous phase separation of the PIL and ionic complexation with an acid, which occurred in a basic solution of a nonsolvent for the PIL. These membranes have a stimuli‐responsive porosity, with open and closed pores in isopropanol and in water, respectively. This property is quantitatively demonstrated in filtration experiments, where water is passing much slower through the membranes than isopropanol.

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110.
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