Onion is a kind of stimulating vegetable. People who like it are like it. People who don’t like it are very repulsive. Because the onion is spicy and pungent, the taste is strong. Many children don’t particularly like onions. Onions are native to Central Asia or West Asia and are widely distributed in China. They are cultivated in all parts of the country. They are one of the main vegetables in China. China's onion originates mainly in Fujian, Shandong, Gansu, Inner Mongolia and Xinjiang. The onions currently available on the market are generally of three kinds: Purple onion, White onion and Yellow onion. The nutrition of three kinds of onions is almost the same. Purple onions have slightly higher nutrition. Three kinds of onions have slightly different taste. Purple onions Rich flavor, suitable for cooking, white onion juice, juicy, light spicy, suitable for salads eaten raw, yellow onion is suitable for cooking with seafood. Onion is a very good health vegetable, rich in nutrients and health-care ingredients. Each 100g of onion contains: Heat (39 kcal) Phosphorus (39 mg) Calcium (24 mg) Magnesium (15 mg) Iron (0.6 mg) Potassium (147 mg) Sodium (4.4 mg) Selenium (0.93 μg) Copper (0.05 mg) Manganese (0.14 mg) Zinc (0.22 mg) Fat (0.2g) Protein (1.1 g) Carotene (20 micrograms) Thiamine (0.03 mg) Riboflavin (0.03 mg) Carbohydrates (9 grams) Niacin (0.30 mg) Dietary fiber (0.9 g) Vitamin C (8.00 mg) Vitamin A (3 micrograms) Vitamin E (0.14 mg) In addition, onions also contain quercetin and prostaglandin A, as well as caffeic acid, sinapinic acid, cinnamic acid, citrates, polysaccharides, and various amino acids. Volatile oil is rich in allicin, thiol, trisulfide and so on. Flower buds, pollen, anthers, etc. all contain carotene. The tearing ingredient of onion is alliin, and the S-propenyl-L-hemisteine ​​hydrosulfide contained in the onion is a precursor of the ring alliin. Under alkaline conditions, the ring can be synthesized Amino acid. It is because of so many special substances that make onions have a lot of health benefits: Onions can prevent cancer The cortex and selenium contained in the onion can stimulate the body's immune response, inhibit the division and growth of cancer cells, and at the same time reduce the toxicity of carcinogens. It can help prevent cancers such as colon cancer, laryngeal cancer and ovarian cancer. Onions can lower blood pressure Onion is currently known, the only vegetable containing prostaglandin A, prostaglandin A is a natural blood thinner, can help dilate blood vessels, reduce blood viscosity, can reduce peripheral blood vessels and increase coronary blood flow, effectively prevent the formation of thrombus . At the same time, prostaglandin A can also act as a booster substance in the human body, catecholamines, and promote the excretion of sodium salts. It is a good food for hypertension, high blood lipids, and health care of patients with cardiovascular and cerebrovascular diseases. Onion can lower blood sugar, diuretic detoxification Onion also contains flavonoids, similar to the hypoglycemic agent sulfamoxine, which can form quercetin in the body. It has a strong diuretic effect and can prevent diabetes and renal edema. Diabetic patients eat 25-30 grams of onions a day, can play a good role in lowering blood sugar and diuretic effect. Onion sulfur components in the large intestine or the intestinal bacteria binding protein, stroke hydrogen sulfide can promote intestinal peristalsis, onions can stimulate intestinal dietary fiber can improve constipation, help detoxification. Onions can increase appetite and help digestion Onion contains onion because it contains garlic, so the onion contains a strong pungent odor, some people think that this smell is not good, but people like the onion and that is very fragrant, it is this smell that can stimulate the secretion of gastric acid, increase Food, onions can also improve the gastrointestinal tension, promote gastrointestinal motility, effectively improve the lack of gastric motility, indigestion caused by loss of appetite. Onions can bactericidal against colds Phytoncide and allicin contained in onion have strong bactericidal ability, can effectively fight cold virus, influenza virus, prevent colds, and these phytoncides are excluded from the body's respiratory tract, urinary tract, sweat glands, can play a role in The role of diuretic and sweating is a good food for fighting germs at the beginning of a cold. Onion or diet food Onions can help lower blood sugar, break down cholesterol, and the onion itself has very low calories. When you enjoy high-fat foods, onions can effectively prevent the body from eating too much cholesterol, which is a good helper for weight loss. Onion or beauty talent Onion rich in vitamin C and nicotinic acid can help the formation of interstitial cells and the repair of damaged cells, making the skin smooth and ruddy and elastic, and effectively prevent the formation of age spots, is a beautiful and inexpensive beauty food. The effectiveness of onions is so much that not everyone is suitable to eat. Onions are not suitable for patients suffering from skin diseases. Onions stimulate the secretion of gastric acid to stimulate the intestines. People with gastrointestinal problems are not suitable for eating onions, which can easily lead to aggravation of the disease. Finally, onions and other spicy vegetables are unsuitable for people with eye diseases and are prone to aggravation. Camera Kits System With 8 Camera The intelligent analysis of intelligent high-definition cameras is mainly aimed at accurate analysis, judgment and alarm of common camera failures such as black screen, blurring, out of control PTZ, picture freezing, and video signal interference such as scene change, items left/disappeared, etc. Camera Kits System With 8 Camera,Wireless Nvr Kit Surveillance system,Retail Store Camera System,8 Channel cctv set,NVR Security Camera Kits System 8Channel Shenzhen Fuvision Electronics Co., Ltd. , https://www.outdoorsolarcameras.com
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Lamp panel
The lamp panel is divided into ordinary infrared lamps (Dingyuan and Guanglei) and array lamps. The array camera is also divided into 1W, 2W and 3W. Therefore, when choosing infrared lamps, if it is an ordinary infrared lamp, try to choose Dingyuan and 3W array lamps. Since the appearance of infrared lamps is generally invisible, some cottage cameras are filled with Guanglei and 1W array cameras are filled with 3W array cameras. Therefore, try to choose a large brand when choosing cameras.
Maximum Aperture
The real value of the maximum aperture is to improve the light intake under low light conditions, so as to achieve the best exposure combination. In general, the ability to visualize the lens is not required for shooting landscapes. In addition, the lens caliber is not required for shooting landscapes except in particularly dark places. However, when the 70-200mm zoom lens is equipped with a 2-fold zoom lens to make the telephoto section become 400mm and AF is used for automatic focusing, it is better to choose a lens with the largest aperture of F2.8. Large aperture is conducive to accurate focusing in dark conditions. When shooting people with a large aperture lens, even in places where the light is weak, the handset can also use natural light to shoot. In addition, the lens with the largest aperture can bring fast shutter speed, so sports photography also needs a large aperture lens.
Another reason for requiring the lens aperture to be large is to be able to visualize the background freely and ensure the quality of visualization. When the aperture of the lens with the maximum aperture of F1.4 is reduced to F2, both the imaging quality and the blurring quality of the background are better than those of the lens with the maximum aperture of F2. Therefore, it is of great value to reduce the aperture of a large aperture lens by one stop. Any photographer should be good at using the lens.
focal length
The first thing to pay attention to when selecting a lens is the focal length of the lens. In fact, focal length is a matter of perspective. Different focal lengths and perspectives are different. In addition, users should be clear about what is the main purpose of buying lenses? Is it for scenery or people. As we all know, it is better to use a wide-angle lens when shooting landscapes, and a telescopic lens when shooting people. Therefore, you should first decide the focal length of the lens you want to buy according to the purpose of photography.
The best focal sections for shooting scenery are 24 mm wide angle focal section and 200 mm telescopic focal section (both are based on 35 mm specifications, the same below). When the wide-angle focus segment of the standard zoom lens evolves from 28mm to 24mm, the viewing angle becomes larger, and the range of scenery that can be stored is greatly expanded. Generally speaking, the maximum aperture of the lens is not required for shooting landscapes. If you are mainly shooting landscapes, a wide angle focal length of 24mm is basically enough when you select a zoom lens. As for the telephoto section, it must be at least 200mm. If the telephoto section is 300mm or 400mm, it is more ideal, and the degree of freedom will be greatly improved. The telephoto focus segment of traditional zoom lens is 300 mm, which is 450 mm for digital SLR. The focal length has been expanded by 1.5 times, which makes it more enjoyable to use. This is the value of digital SLR. The wide-angle focal section of the digital special ultra wide-angle lens produced is generally 12mm, equivalent to 18mm of 35mm, which is nearly 1.5 times larger than the 28mm focal section of 35mm, thus greatly widening the left and right range of the scenic scene.
The best focal length for shooting people is 85mm. In terms of 35mm standard, 85mm focal length is basically used as the standard for shooting characters. The portrait taken by the 85mm focal section is basically close to the picture effect taken by the medium frame camera. It is not only suitable for the distance, but also the face of the person looks very natural. The distance between the camera and the person being photographed can basically be kept at the normal speaking distance. The 85mm focal length can also effectively blur the background and prominent characters. In order to obtain good visualization effect, the lens with the largest aperture should be selected. The 85mm focal length is about 135mm on the digital SLR. Although the sense of distance of the shot is a little weak, it is basically OK, so the focal length of the person lens should be at least about 85mm.
A 100mm macro lens is enough for traditional SLR to shoot flowers. The 100mm macro lens can be used for equal magnification photography, which can make the flowers very large. However, when taking equal magnification photography or near equal magnification photography, due to the depth of the long focus scene, it is easy to shake, so anti shake measures should be considered when taking photos. From this point of view, 50mm macro lens is easier to use on digital SLR.