1. When writing the famous work "The Evergreen Tree of Life", Xu Chi not only conducted in-depth interviews with Mr. Cai Xitao, but also traveled thousands of miles and traveled long distances, visiting Xishuangbanna three times. There, he saw all kinds of strange trees, which was an eye-opener. Xu Chi recorded the shapes, colors, and properties of these trees in his notebook one by one, and made full use of them when writing, so that the work vividly reflected the lofty spirit of scientists who were dedicated to their careers and constantly explored. 2. The story of Xu Chi's "three trips to Xishuangbanna" gives us profound inspiration: writing cannot rely solely on one's own subjective imagination, but must go into life and master first-hand materials, so as to make the article vivid and true and attract readers. 3. Feats in the Navigation Industry In human history, at the end of the century, Portuguese navigator Vasco da Gama completed the first voyage from Western Europe around the southern tip of Africa to India. His voyage opened up an east-west sea channel and had a significant impact on the development of world history. After the Portuguese navigator Dias discovered the Cape of Good Hope on his maiden voyage in 1488 AD, in July 1497, Vasco da Gama led a fleet to embark on an earth-shattering and ghostly shipping feat. Vasco da Gama's fleet arrived at the port of Malindi in Kenya shortly after passing through Mozambique. According to historical records, as early as 1417, Zheng He, the famous navigator of the Ming Dynasty of China, led his fleet to arrive at this port and left a permanent commemorative mark here. After Vasco da Gama discovered a merchant ship from India in Malindi Port, he took advantage of the southwest monsoon and sailed continuously for twenty-three days to reach the important town of Kahekut in India, completing this unprecedented feat of voyage. 4. Use your son as the first experimenter. In the 18th century, smallpox spread like a terrible plague in Europe and Asia. Almost everyone in Britain was infected with the disease sooner or later. Many adults had ugly scars on their faces and bodies. Thousands of people became blind or mad and died every year because of the severity of the disease. There are countless people. The discoverer of immunization, the British Jenner, was still a young engineer at that time, and he was determined to fight smallpox. Through observation and experiments, he found that smallpox could be prevented by artificial vaccination of animals with cowpox. So, what was the result of the experiment on humans? At the risk of killing his son, and enduring all kinds of criticism from relatives and friends, Jenner planted acne slurry on his son's arm, and two months later he planted pus from a smallpox patient. The liquid was planted on his son, and he did not contract smallpox. His experiment was a success. 5. “Isn’t the human chest similar to a wine barrel?” In the mid-18th century, there was a doctor named Ambrugger in Vienna, the capital of Austria. Once, he treated a patient who had chest pain, shortness of breath, and fever. However, he could not find out the crux of the problem and it was difficult to take medication. The patient died soon after. After an autopsy, it was discovered that the chest cavity was filled with pus. The doctor thought, what should he do if he encounters this kind of patient in the future? He suddenly remembered that when his father was running the wine business, he often rapped wooden wine barrels with his knuckles: after listening to the sound, he could estimate the amount of wine in the barrel. How much wine. "Isn't the human chest a long barrel? Can a diagnosis be made based on the sound of tapping the patient's chest with his hands?" So he repeatedly observed cases and performed pathological anatomy to explore the relationship between chest diseases and percussion sound changes. Due to the relationship, he finally wrote the medical paper "A New Method for Detecting Internal Thoracic Diseases by Percussing the Human Chest" and invented the diagnostic method of "percussion". 6. The birth of Ohm’s law Georg Simon Ohm (1787-1854) was a German physicist. Born in Erlangen, Bavaria. Ohm's father was a skilled locksmith who was very interested in philosophy and mathematics. Ohm studied mathematics and received training in mechanical skills under his father's education since he was a child, which was of great help to his later research work, especially homemade instruments. He received a classical education in middle school in 1800. In 1803, he was admitted to the University of Erlangen and taught in a middle school before graduating. In 1811 Ohm returned to Erlangen to complete his university studies and passed the examination to obtain a doctorate in philosophy in 1813. In 1817, his "Textbook of Geometry" was published. In the same year, he applied to teach physics and mathematics at the preparatory course of the University of Cologne. In the school's well-equipped laboratories, a large number of experimental studies were conducted and a series of important inventions were completed. His most important contribution was the experimental discovery of the formula for electric current, later known as Ohm's law. In 1826, he wrote these research results into a paper titled "Determination of the Laws of Conductivity of Metals" and published it in the German "Journal of Chemistry and Physics". Ohm theoretically derived Ohm's law in his book "Mathematical Research on Power Circuits" published in 1827. In addition, he also made contributions to acoustics. In 1833, he went to the Nuremberg Polytechnic as a professor of physics. In 1841, Ohm won the Coheli Medal of the Royal Society of London, England, and the next year he was elected as a foreign member of the society. In 1852, he was appointed professor at the University of Munich. To commemorate him, people named the unit of resistance ohms. Its definition is: when a steady current of 1 ampere passes between two points in the circuit, if the voltage between the two points is 1 volt, then the resistance of the conductor between the two points is defined as 1 ohm. In 1805, Ohm entered the University of Ireland to study, but was forced to drop out in 1806 due to family financial difficulties. Through self-study, he returned to the University of Ireland in 1811 and successfully obtained a doctorate.

After graduating from college, Ohm made a living by teaching. From 1820 onwards, he began to study electromagnetism. Ohm's research work was carried out under very difficult conditions. Not only did he have to be busy with teaching work, but he also lacked books, materials and instruments. He could only use his spare time to design and make instruments by himself to conduct relevant experiments. In 1826, Ohm discovered an important law in electricity - Ohm's law, which was his greatest contribution. This law seems simple to us today, but its discovery process is not as simple as most people imagine. Ohm worked very hard for this. At that time, people were not very clear about the concepts of current intensity, voltage, resistance, etc., especially the concept of resistance. Of course, there was no way to accurately measure them; besides, Ohm himself was very important in his research process. He had almost no opportunity to contact the physicists of his time, so he made this discovery independently. Ohm's initial experiments were mainly to study the conductivity of various metal wires, using various conductors to observe the deflection angle of the magnetic needle. Later, while experimenting with changing the electromotive force on the circuit, he discovered the dependence between the electromotive force and resistance. This is Ohm's law. This law can be expressed in two forms: one is Ohm's law for a partial circuit, the current passing through the partial circuit is equal to the voltage across the partial circuit divided by the resistance of the partial circuit; the other is Ohm's law for the whole circuit, that is, through The current in a closed circuit is equal to the electromotive force of the source in the circuit divided by the total resistance in the circuit. When Ohm's research results were first announced, they did not attract the attention of the scientific community and were attacked by some people. It was not until 1841 when the Royal Society awarded Ohm the Kopler Medal that Ohm's work was generally recognized. The Kopler Prize was the highest honor in science at the time. In July 1854, Ohm died in Mannach, Germany.