Abstract:
Compounds are provided that generally have the structure BCH.sub.2 CH(R)OCH.sub.2 P(O)(OH).sub.2, wherein B is a purinyl or pyrimidinyl base and R is C.sub.1-2 alkyl substituted with azido or amino, straight or branched alkenyl of 2-6 carbon atoms or alkynyl of 2-6 carbon atoms, together with the monester and diesters of such compounds with a C.sub.1-5 alkanol, and the corresponding salts, hydrates, solvates, the (R) or (S) isomers and the racemic (RS) mixtures thereof. The compounds have desirable antiviral activity.
Abstract:
The present invention relates to a compound of formula I ##STR1## or a nontoxic pharmaceutically acceptable salt, physiologically hydrolyzable ester or solvate thereof, in whichX is --O--CO--, --NH--CO--, --CS--NH--, --CO--O--, --CO--NH--, --COS--, --SCO--, --SCH.sub.2 --, --CH.sub.2 --CH.sub.2 --, --C.tbd.C--, --CH.sub.2 --NH--, --COCH.sub.2 --, --NHCS--, --CH.sub.2 S--, --CH.sub.2 O--, --OCH.sub.2 --, --NHCH.sub.2 -- or --CR.sup.5 .dbd.CR.sup.6 --;R.sup.m and R.sup.k are independently hydrogen, halogen, C.sub.1-6 alkyl, hydroxy, C.sub.1-6 alkyloxy or nitro;n is zero or one;R.sup.4 is --(CH.sub.2).sub.t --Y, C.sub.1-6 alkyl, or C.sub.3-6 cycloalkyl;R.sup.1 is --CO.sub.2 Z, C.sub.1-6 alkyl, CH.sub.2 OH, --CONHR.sup.y, or CHO;R.sup.2 and R.sup.3 are independently hydrogen or C.sub.1-6 alkyl;R.sup.a and R.sup.b are independently hydrogen or C.sub.1-6 alkyl; but when n is one, R.sup.a and R.sup.b together can form a radical of the formula ##STR2## Y is naphthyl or phenyl, both radicals can be optionally substituted with one to three same or different C.sub.1-6 alkyl or halogen;Z is hydrogen or C.sub.1-6 alkyl;R.sup.5, R.sup.6 and R.sup.y are independently hydrogen or C.sub.1-6 alkyl; andt is zero to six.
Abstract:
An apparatus feeds raw material bars to a furnace body of a melting furnace, and includes an enclosure body provided with a vertical feed passage to be disposed above an open top side of the furnace body. A feeding unit includes a push mechanism extending into an upper part of the feed passage, and a material retarder extending into a lower part of the feed passage. A transferring unit transfers a raw material bar to the feed passage in a manner that the raw material bar extends vertically in the feed passage. The push mechanism pushes the raw material bar in the feed passage downwardly, and the material retarder retards downward movement of the raw material bar out of the feed passage and into the furnace body.
Abstract:
A control mechanism for a high-voltage generator for supplying voltage and current to an electronic radiation source in high-temperature environments is provided, the control mechanism including at least one voltage feedback loop for monitoring the output of the generator; at least one environmental temperature monitor; a control bus; and at least one control processor. A method of controlling a high-voltage generator that powers an electronic radiation source in high-temperature environments is also provided, the method including at least: measuring the output voltage of the generator; measuring the temperature within the generator's environment, using a control mechanism to modify a driving frequency, and using a control mechanism to modify a driving pulse-train, such that changes in properties of the electronic components of the generator as a result of changes in environmental temperature are characterized and the generator's driving signals modified to maintain optimally efficient input parameters for a specific environmental temperature.
Abstract:
A segmented magneto-conductive structure applied in rotating machines comprises a rotor assembly and a stator assembly. The rotor assembly includes a rotor yoke component and a plurality of rotor teeth components. The rotor yoke component is made of non-oriented silicon steel. The rotor teeth components are made of grain-oriented silicon steel. The stator assembly includes a plurality of stator yoke components and a plurality of stator teeth components. The stator yoke components and the stator teeth components are made of grain-oriented silicon steel. Thereby, an operational efficiency of a motor applying the segmented magneto-conductive structure is enhanced.
Abstract:
An electronic load for testing stability of a power voltage of a power source under test (PSUT) includes a voltage supply device, a field effect transistor (FET), an amplification circuit, and a current sampling resistor. The amplification circuit includes a first input, a second input, and an output. The voltage supply device is connected to the first input. The second input is connected to a source electrode of the FET. The output is connected to a gate electrode of the FET. A drain electrode of the FET is connected to the PSUT. One end of the current sampling resistor is grounded, and the other end of the current sampling resistor is connected to the source electrode of the FET and the second input. The voltage supply device outputs a control voltage. The amplification circuit amplifies the control voltage and drives the FET using the amplified control voltage.
Abstract:
A resistance-measuring circuit includes a controller for outputting a PWM signal and further for adjusting the duty cycle of the PWM signal, and a sampling circuit for processing the PWM signal and transmitting the processed PWM signal to the sensor. The sampling circuit samples the signal outputted from the sensor to generate a sampled signal with the voltage thereof changing according to any change in the duty cycle of the PWM signal, and further transmits the sampled signal to the controller. The controller obtains the real-time duty cycle of the PWM signal when the voltage of the sampled signal reaches a threshold voltage, and further calculates the exact resistance of the sensor according to the obtained real-time duty cycle of the PWM signal and the threshold voltage. An electronic device with the resistance-measuring circuit is also provided.
Abstract:
An ADC includes an analog signal input port for receiving analog signals, a reference voltage generation circuit for producing a reference voltage, a controllable switch, a control unit including a counter, an integral circuit, and a comparison circuit. The control unit outputs an on or off signal to turn on or turn off the controllable switch, the counter starts to count when the control unit outputs the off signal. The integral circuit executes an integral action to integrate the reference voltage and output a voltage enhanced gradually when the controllable switch is turned off. The comparison circuit outputs an interrupt signal to cause the counter to stop counting when comparing the voltage output by the integral circuit is higher than the voltage of the analog signals. The control unit determines a digital value corresponding to the analog signals according to a count value of counted by the counter.
Abstract:
A sensing circuit includes a plurality of sensors, a controller, a multiway switch, a linear optocoupler, and a logical control unit. The plurality of sensors are capable of measuring physical quantity, and each of the plurality of sensors is capable of generating a sensing signal in accordance with the physical quantity. The controller is capable of receiving and analyzing the sensing signals, and transforming the sensing signals into sensing events. The multiway switch is capable of selectively connecting one of the plurality of sensors to the controller. The linear optocoupler is connected between the plurality of sensors and the controller. The logical control unit is capable of controlling the multiway switch to selectively connect one of the plurality of sensors to the optocoupler, and generating a control signal to the controller, wherein the control signal indicating the one of the plurality of sensors connected to the controller.
Abstract:
A charging circuit includes a battery pack having a plurality of serially connected batteries and being connected to a power supply; a changeover switch being serially connected to and between any two adjacent batteries; and a precision voltage detector being parallelly connected to each of the batteries for independently detecting a voltage of the connected battery and sending out a detected result to a charging control circuit for controlling the ON/OFF of the changeover switch corresponding to the battery. When a battery is detected by a corresponding precision voltage detector as having been fully charged, the corresponding charging control circuit sets the changeover switch corresponding to the battery to OFF to stop charging the battery. The remaining batteries that are subsequently fully charged are disconnected from the power source one by one until all the batteries in the battery pack have been fully charged. Thus, all the batteries are balance-charged.