China's basic scientific research has made much progress despite very difficult financial conditions. In high-energy physics, it has established its own research base for high-energy physics, has a positive-negative electron collider best suited to work in the energy region of charmed-particle physics, has installed an ultrahigh-energy emulsion chamber at Gambala Mountain at an altitude of 5,500 meters, and has gained such achievements as the discovery of the anti-Sigma negative tachyon, the laminar model of particle physics, and the pseudo-vectorial part of the flow conservation laws and the calibration of the tauon mass, among other achievements.
In nuclear physics, a 1.5-meter heavy-ion gas pedal was built, research on low-energy heavy-ion nuclear physics was carried out, and the transuranic element californium was synthesized for the first time, among others. In addition, 1.5 mega-electron volt linear induction gas pedal, synchrotron radiation device, isotope separator, controlled fusion device and scanning tunneling microscope and other scientific research equipment, as well as large aperture reflecting telescope, solar magnetic field telescope, 13.7 millimeter-wave radio telescope, hydrogen atomic clock and other astronomical instruments were built.
In the field of basic research has achieved a number of important results, such as Goldbach's Conjecture in the field of mathematics and science, the standard algorithm of the finite element method, the machine proof of mathematical theorems, the stability of differential dynamical systems, the theoretical method of molecular orbital graphs, the theory of warm cloud precipitation, the discovery of the Earth's inner core rotating a little faster, the synthesis of bovine insulin in the field of life sciences, the synthesis of yeast alanine transfer Ribonucleic Acid (RNA), the study of the relationship between structure and function in insulin, and the study of the relationship between structure and function of proteins. structure-function relationship study, protein function gene modification, rice gene physical mapping, as well as the discovery of comets and asteroids, the discovery of quasi-crystals, the discovery of ancient fossils of plants and animals such as the Chengjiang fossil group, and there are numerous harvests in the study of biological nitrogen fixation and photosynthesis, the study of the atmospheric circulation in East Asia, the study of the paleoclimate and the paleoNova, the exploration of the source of the Yellow River, the Yarlung Zangbo River exploration, as well as expeditions to the Antarctic and the Arctic, and other aspects.
An important sign of technological progress is the ability to master high technology. Chinese scientists and engineers have mastered nuclear technologies such as the manufacture of atomic bombs, hydrogen bombs, nuclear power generation and nuclear radiation, as well as the launching of long-range carrier rockets, artificial Earth satellites for various purposes and even spaceships, and the manufacture of electronic computers such as the 1-billion-times gigantic machine, the 10-million-times vector machine. Millions of times ultra-small machine and Shuguang 1 and Shuguang 1000 and other high-performance parallel machines, the development of temporal logic language, Chinese language information processing system, Chinese language conversion system and other software systems, the development of the Chinese language intelligent interfaces and high-density information storage devices, in the quantum computation and quantum communication has also been the principle of quantum error-avoidance and quantum cryptomorphic experiments promising progress.
In the field of laser technology, we have developed high-power laser devices such as "Shenguang", semiconductor quantum trap lasers, free-electron laser devices and 1.35-micron semiconductor lasers and other laser systems, and mastered high-speed optical fiber communication technology. The original dual-ion beam epitaxial machine, the breakthrough of the 3-micron integrated circuit process, as well as the manufacture of nuclear industry robots, six-dimensional robots, wall-climbing robots and other robots, and the success of the 6,000-meter underwater robots to explore the sea experiments, representing our progress in precision manufacturing.
In biotechnology, there have been remarkable achievements in biotechnology, such as nitrogen fixation in corn and soybeans, insect-resistant cotton flowers, genetically engineered vaccines, test-tube babies and test-tube sheep, expression of human genes in plants and cloning of higher animals. In materials science, research on high-temperature superconductor materials and nanomaterials, high-performance solid propellants, nonlinear crystals, and laser crystals have all made promising achievements.
In technical sciences, there are also influential theoretical achievements such as the theory of compound combustion, the theory of ternary flow of impeller machinery, the equation of state of cold pressure, the theory of overall error in gear dynamics, and the optimal control of nonlinear systems.
Engineering progress is highlighted in the manufacturing capacity of large-scale equipment, China has been able to manufacture 125,000 kilowatts of double water-cooled turbine generator sets, 175,000 kilowatts of low head generator sets, 500,000 kilowatts of high-voltage transmission equipment, 200-ton electroslag remelting furnaces, 15,000 tons of polyester drawing equipment, 240,000 tons of urea production, 300,000 tons of ammonia equipment, 10 million tons of open-pit mining equipment. 10 million tons of open-pit mining equipment.
The Yangtze River bridges at Wuhan and Nanjing, the Gezhouba Dam on the Yangtze River and Xiaolangdi on the Yellow River, and the Three Gorges Project under construction represent bridge and dam construction capabilities, while the progress in transportation is shown by the construction of megaships, 7 passenger planes, highway construction, and speeding up of trains.
The successful development of the Daqing oil field fully demonstrates the strength of China's self-reliance policy, while air-jet spinning and synthetic rubber show the ability to absorb and innovate technology.
The contribution of science and technology to agricultural progress has reached 35 percent, and great progress has been made in the promotion of good seeds and the reform of farming systems. Indica hybrid rice, Lu cotton 1 cotton, Tiefeng 1 and Dongnong 36 soybeans and wheat and the promotion of good seeds has played a huge role in increasing crop yields, crop varieties have been replaced four or five times in the past 51 years, each time increasing yields by 20% to 30%, the main crops of good seed coverage has reached 80%, afforestation survival rate increased by 20%, the replanting index increased by 25%.
In the field of medicine and health, microsurgery and early diagnosis of cancer show the progress of medical technology, genetically engineered peptide drugs, wizard drugs and antibody engineering have made promising progress, the hepatitis B genetically engineered vaccine has replaced the blood-borne vaccine on the market, and there are also the accomplishments of acupuncture anesthesia and yang jinhua anesthesia as well as anti-malarial artemisinin drugs in traditional Chinese medicine, and the achievements of the theory of family planning and population Successes in family planning and population theory have caught the world's attention.
Here are some basic knowledge ideas for grades 3-6:
Objects sink and float in water, and there are certain criteria for determining whether an object is sinking or floating.
Objects made of the same material do not change their sinking and floating status by changing their weight and volume.
The sinking and floating of an object is related to its own weight and volume.
Objects made of different materials tend to sink if they are of the same volume if they are heavy, or if they are of the same weight if they are small.
Submarines apply the principle of sinking and floating of objects in water.
Changing the amount of water an object displaces, the sinking and floating of the object in water may change.
The reason a boat made of steel floats on water is because it discharges a large volume of water.
The same weight of playdough floats more easily the greater the volume of water in which it is submerged, and its loading capacity increases.
Science and technology are closely linked and they have made great contributions to human development.
Pressing the boat and the Styrofoam block into the water, the hand can feel that the water has an upward force on the boat and the Styrofoam block, which we call the buoyancy of the water.
Both floating and sinking objects are buoyant in the water, and we can feel the buoyant force and measure it with a dynamometer.
Objects are buoyant in water, and the greater the volume of an object immersed in water, the greater the buoyant force.
Objects float when the buoyant force in the water is greater than the force of gravity; they sink when the buoyant force in the water is less than the force of gravity); objects that float on the surface of the water have buoyancy equal to the force of gravity.
The sinking and floating of objects in water is related to the nature of the materials and liquids that make them up.
The nature of the liquid can change the sinking and floating of an object.
It takes a certain concentration of liquid to change the sinking and floating of an object, and there are many such liquids.
Different liquids have different magnitudes of buoyancy effects on objects.
Objects heavier than the same volume of water sink in water, and objects lighter than the same volume of water float in water.
Objects heavier than the same volume of liquid, sink in the liquid, and objects lighter than the same volume of liquid, float in the liquid.
There are several ways to produce heat.
Adding clothes makes the body feel hot, but it is not the clothes that add heat to the body.
Water increases in volume when it is heated, while its weight remains the same.
Water expands when it is heated and shrinks when it is cooled, and we call this change in the volume of water thermal expansion.
Many liquids increase in volume when they are heated and decrease in volume when they are cold.
The change in volume of an object from cold to hot or from hot to cold can be felt by our senses or observed by certain devices and experiments.
Gases expand when they are heated and shrink when they are cold.
Common objects are made up of particles, which are always in constant motion. The thermal expansion and contraction of an object is related to the motion of the particles.
Many solids and liquids have the property of thermal expansion and contraction, as do gases.
Some solids and liquids are heat-expanding and cold-expanding under certain conditions, for example, the metals antimony and bismuth are heat-expanding and cold-expanding.
Heat is a form of energy, and heat can be transferred from the hotter end of an object to the cooler end, and from the hotter object to the cooler one, until both are the same temperature.
Heat transfer occurs mainly by three means: heat conduction, convection, and heat radiation.
The method of heat transfer by which heat is transferred from one object to another, or from one part of an object to another, by direct contact is called heat conduction.
Objects that conduct heat well like metals are called good conductors of heat; while objects that conduct heat poorly like plastics and wood are called bad conductors of heat.
Bad conductors of heat slow down the dissipation of heat from an object.
Our subjective perception of the same amount of time will be different in different situations, but time is extending at a constant rate.
With the help of things or phenomena in regular motion in nature, we can estimate time.
Time can be measured by observing the cycles of the sun's motion and the shadows formed by its casting, and some devices with regular motion have been used to measure time.
The direction and length of an object's shadow in sunlight changes slowly. Sundials and gui watches are timepieces made from the length of the sun's shadow.
With a certain device, running water can be used to tell time because a drip keeps water flowing downhill at a steady rate for a certain amount of time.
There are two ways to time dripping water: one is to use a special container to record the time it takes for the water to finish leaking (the drain type); the other is a container with no opening at the bottom, which records the amount of time it takes to catch the water to the top (the receiving type).
People have long sought precise timekeeping methods, and as science and technology have developed, people have made increasingly accurate timekeeping tools.
While some simple clocks like sundials and water clocks, as well as fuel clocks and hourglasses, can already give us an idea of the approximate time, people always want more accurate clocks. The advent of the pendulum clock greatly improved the accuracy of clocks.
The same pendulum takes the same amount of time to swing once. Based on the isochronous nature of the pendulum, pendulum clocks were made to make the measurement of time even less inaccurate.
The speed of a pendulum's swing is related to the length of its string. For the same pendulum, the longer the string, the slower the swing, and the shorter the string, the faster the swing.
The speed of the pendulum is related to the length of the pendulum.
In the same pendulum, the longer the length of the pendulum, the slower it swings, and the shorter the length of the pendulum, the faster it swings.
Note that the length of the pendulum rope is not equal to the length of the pendulum; the length of the pendulum is the distance from the support to the center of gravity of the pendulum.
Mechanical pendulum clocks are pendulums working in conjunction with a gear manipulator.
There are a number of possible explanations for the phenomenon of alternating day and night.
The phenomenon of day and night is related to the relative circular motion of the earth and the sun.
When the Foucault pendulum swings, the dial on the ground is deflected from the direction of the pendulum's swing, which can prove that the Earth is rotating. The Foucault pendulum is the key piece of historical evidence that proves that the Earth rotates.
The eastward rise and westward fall of celestial bodies is a phenomenon that occurs as a result of the Earth's rotation.
The difference in longitude in which different regions are located determines the time difference between regions.
People use the longitude of the Earth as a standard to divide the Earth into 24 time zones. The longitude line that passes through Greenwich Observatory in London, England, is designated as the 0-degree meridian. From the 0 degree meridian to the east 180 degrees belongs to the east longitude, to the west 180 degrees belongs to the west longitude. Every 15 degrees of the meridian is a time zone, and the time difference between two neighboring time zones is one hour.
The stars in the sky rotate clockwise around Polaris, and Polaris is relatively "motionless", a phenomenon produced by the rotation of the Earth.
From the position of Polaris in the sky, it can be inferred that the Earth's axis is tilted.
The annual parallax of the stars proves that the Earth is indeed rotating around the Sun. Other evidence supports this.
When rotating around an object, visual positional differences are observed at different locations in the rotational orbit for objects near and far.
The formation of the seasons is related to the rotation of the Earth and the tilt of its axis.
The phenomena of extreme day and night are related to the rotation of the Earth, the rotation of the Earth, and the tilt of the Earth's axis.