银。具有原子符号ag的元素 silver. an element with the atomic symbol ag, 原子序数47 atomic number 47, 和原子量107.87。它是一种软金属，用于医疗器械 and atomic weight 107.87. it is a soft metal that is used medically in surgical instruments, 假牙 dental prostheses, 和合金。长时间连续使用银盐会导致一种中毒形式，称为银精症。在金属之间 and alloys. long-continued use of silver salts can lead to a form of poisoning known as argyria. Among metals, 纯银具有最高的导热率（非金属金刚石和超流体氦ii更高），也是最高的光学反射率之一。 （在可见光谱的某些部分，铝略胜于银 pure silver has the highest thermal conductivity (the non-metal diamond and superfluid helium II are higher) and one of the highest optical reflectivity. (Aluminium slightly outdoes silver in parts of the visible spectrum, 石竹香粉花丁香粉丁香花粉紫丁香花香粉丁香粉紫罗兰花粉丁香粉石竹粉花粉金宝花石竹粉花粉桃金娘粉从干燥得到的粉 and silver is a poor reflector of ultraviolet light). Silver also has the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for their ability to record a latent image that can later be developed chemically. Silver is stable in pure air and water, 但是当暴露于空气或含有臭氧或硫化氢的水中会失去光泽，形成黑的硫化银层，可用稀盐酸将其清除。银最常见的氧化态是+1（例如 but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide to form a black layer of silver sulfide which can be cleaned off with dilute hydrochloric acid. The most common oxidation state of silver is +1 (for example, silver nitrate: agno3）;此外 AgNO3); in addition, +2种化合物（例如 +2 compounds (for example, 氟化银 silver(II) fluoride: agf2）和+3化合物（例如 AgF2) and +3 compounds (for example, 四氟精酸potassium tetrafluoroargentate: k [agf4]）是已知的。希波克拉底 K[AgF4]) are known.; Hippocrates, the "父亲 father of 药物 medicine", 写道，银具有有益的愈合和抗疾病特性 wrote that silver had beneficial healing and anti-disease properties, 以及曾经用来储存水的腓尼基 and the Phoenicians used to store water, 葡萄酒 wine, and 醋 vinegar in silver 瓶子 bottles to 避免 prevent 宠坏 spoiling. In the 早 early 1900s people 将 would put silver 美元 dollars in 牛奶 milk 瓶子 bottles to 延长 prolong the 牛奶 milk's 新鲜 新鲜 freshness. its Its 杀菌的 germicidal 效果 effects 增加 increased its value in 餐具 utensils and as 首饰 jewellery. The 精确 exact 处理 process of silver's 杀菌的 germicidal effect is 仍然 still not well 被理解 understood, 尽管理论存在。其中之一是微动力效应 although theories exist. One of these is the oligodynamic effect, 解释了对微生物的作用，但没有解释抗 作用。珠宝和银器传统上是由纯银（标准银）制成 which explains the effect on microorganisms but would not explain antiviral effects.; Jewellery and silverware are traditionally made from sterling silver (standard silver), 一种由92.5％的银与7.5％的铜组成的合金。在美国 an alloy of 92.5% silver with 7.5% copper. In the United States, only an 合金 alloy 组成 consisting of at 最小 least 92.5% fine silver can be 上市 marketed as "silver". 英镑 Sterling silver is 更难 harder than pure silver, 熔点（893？c）比纯银或纯铜低。不列颠尼亚白银是一种替代的标志性质量标准，其中含有95.8％的白银 and has a lower melting point (893 �C) than either pure silver or pure copper. Britannia silver is an alternative hallmark-quality standard containing 95.8% silver, 常用于制作银色餐具和锻制盘子。加上锗 often used to make silver tableware and wrought plate. With the addition of germanium, 形成获得专利的改性合金纯银 the patented modified alloy Argentium Sterling Silver is formed, 具有改善的性能，包括耐火垢性。溴化银为黄 with improved properties including resistance to firescale.; Silver bromide is a yellow, 低硬度盐。银是一种化学元素，化学符号为a（拉丁 low hardness salt.; Silver is a chemical element with the chemical symbol Ag (Latin: 阿根廷）和原子序数47。 argentum) and atomic number 47. A soft, 白 white, 有光泽的过渡金属 lustrous transition metal, 它具有所有元素中最高的电导率和所有金属中最高的热导率。金属纯净地自然存在 it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. The metal occurs naturally in its pure, 自由形式（本机银） free form (native silver), 作为与金（电子）和其他金属的合金 as an alloy with gold (electrum) and other metals, 以及诸如银辉石和绿泥石的矿物。大多数银是铜的副产品 and in minerals such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, 和锌精炼。银几乎是所有有色克拉金合金和克拉金焊料的成分 and zinc refining.; Silver is a constituent of almost all colored carat gold alloys and carat gold solders, 使合金的颜色更浅，硬度更高。 9克拉白黄金包含62.5％的银和37.5％的金 giving the alloys paler colour and greater hardness. White 9 carat gold contains 62.5% silver and 37.5% gold, 4-氨基丁酸γ-氨基丁酸γ-氨基丁酸天然4-氨基丁酸4-氨基丁酸g-氨基-正丁酸γ-氨基-正丁酸4-氨基丁酸γ-氨基丁酸4-氨基丁酸g-氨基丁酸γ -氨基丁酸（gaba）丁酸 while 22 carat gold contains up to 8.4% silver or 8.4% copper.; Silver is a very ductile and malleable (slightly harder than gold) monovalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, 甚至比铜高 even higher than copper, 但其较高的成本和失去光泽性使其无法广泛用于代替铜用于电气目的 but its greater cost and tarnishability have prevented it from being widely used in place of copper for electrical purposes, 虽然13 though 13,fda 131部分-牛奶和奶油b部分-特定标准化牛奶和Creamsec的要求。 131.111酸化的牛奶。fda第131部分-牛奶和奶油b子部分-特定标准化牛奶和Creamsec的要求。 131.112养殖牛奶.fda第131部分-牛奶和奶油子部分b-特定标准化牛奶和Creamsec的要求。 131.170 eggnog.fda第131部分-牛奶和奶油b部分-特定标准化牛奶和Creamsec的要求。 131.200酸奶.fda第131部分-牛奶和奶油t b-特定标准化牛奶和Creamsec的要求。 131.203低脂酸奶.fda第131部分-牛奶和奶油b部分-特定标准化牛奶和Creamsec的要求。 131.206脱脂酸奶。 540 tons were used in the electromagnets used for enriching uranium during World War II (mainly because of the wartime shortage of copper). Another notable exception is in high-end audio cables.; Silver is commonly used in catheters. Silver alloy catheters are more effective than standard catheters for reducing bacteriuria in adults in hospital having short term catheterisation.This meta-analysis clarifies discrepant results among trials of silver-coated urinary catheters by revealing that silver alloy catheters are significantly more effective in preventing urinary tract infections than are silver oxide catheters. Though silver alloy urinary catheters cost about $6 more than standard urinary catheters, 他们 they may be 价值 worth the 额外 extra 成本 cost since 导管相关 catheter-related infection is a common 原因 cause of 医院的 nosocomial infection and 菌血症 bacteremia.; Silver is widely 分散式 distributed in the earth's crust and is 发现 found in 泥 soil, 淡水和海水 fresh and sea water, 和空气。它很容易通过食物和饮料以及吸入途径被 体吸收 and the air. It is readily absorbed into the human body with food and drink and through inhalation, 但是血液中通常存在少量的银（ but the low levels of silver commonly present in the bloodstream (< 2.3 b.mu g/L) and in key tissues like liver and kidney have not been associated with any disease or disability. Silver is not an acknowledged trace element in the human body and fulfills no physiological or biochemical role in any tissue even though it interacts with several essential elements including zinc and calcium. Physiologically, it exists as an ion in the body. Silver has a long history in the treatment of human diseases, including epilepsy, neonatal eye disease, venereal diseases, and wound infections. It has been employed in water purification and is currently used to safeguard hospital hot water systems against Legionella infections. Principle routes of human exposure to silver nowadays are through its widespread use as an antimicrobial agent in wound care products and medical devices, including in-dwelling catheters, bone cements, cardiac valves and prostheses, orthopedic pins, and dental devices. In each case, the antimicrobial properties of silver are dependent upon release of biologically active silver ion (Ag*) from metallic silver (including nanocrystalline forms), silver nitrate, silver sulfadiazine, and other silver compounds incorporated in the various devices, and its lethal effect on pathogenic organisms.; Experience has shown that a large proportion of the silver ion released from medical devices not required for antimicrobial action is disseminated into tissue fluids and exudates, where it combines with albumins and macroglobulins. These silver-protein complexes are absorbed into the systemic circulation to be deposited in key soft tissues, including the skin, liver, kidney, spleen, lungs, and brain. As a xenobiotic material, silver must be presumed to present a health risk to exposed persons under some circumstances. Unlike the well-documented neurotoxic metals including lead and mercury, silver does not appear to be a cumulative poison and is eliminated from the body through the urine and feces. Excretion of silver by these routes may be a measure of mean daily intake, but since this view is based largely on the clinical use of silver nitrate and silver sulfadiazine used in burn wound therapy, its true relevance in the metabolism of silver used in the wider context of medical devices is questionable.; Argyria is the most widely publicized clinical condition associated with silver accumulation in blood and soft tissues. It commonly occurs in individuals exposed to high levels of silver occupationally (metallurgy, photography, and mining industries), or consuming or inhaling silver hygiene products (including colloidal silver products) for long periods. Silver is absorbed into the body and deposited in the perivascular regions of the skin and other soft tissues as black granules of silver sulfide or silver selenide. The resulting slate grey discoloration of the skin occasionally associated with melanogenic changes, is semipermanent and cosmetically undesirable but is not known to be life-threatening. (PMID: 17453933); The price of silver is important in Judaic Law. The lowest fiscal amount that a Jewish court, or Beth Din, can convene to adjudicate a case over is a shova pruta (value of a Babylonian pruta coin). This is fixed at 1/8 of a gram of pure, unrefined silver, at market price.