Agar was first introduced into the laboratory in 1881. Since then, microbiologists have depended on agar to create strong jellies. When microorganisms are streaked or plated onto this jellied surface and incubated, individual cells multiply into distinct colonies that scientists can easily observe, select, and propagate for further experiments. Many of the most important findings in biological research of the last 150 years or so — including the discovery of the CRISPR/Cas9 gene-editing tool — have been enabled by agar.4 Agarose, a derivative of agar, is also essential in molecular biology techniques like gel electrophoresis, where its porous gel matrix separates DNA fragments by size, enabling researchers to analyze and isolate specific genetic sequences.
《乡愁》是日记中浓墨重彩的一笔，也是塔可夫斯基人生的重要转折点。拍摄期间是勃列日涅夫执政后期，苏联的改革趋于保守，经济发展陷于停滞，文化政策一再缩紧，艺术被视作服务于政治的宣传工具。莫斯科电影制片厂的体制化管理和官僚化做派，让塔可夫斯基的创作空间被不断挤压。他在1973年10月的日记中写下的压抑和不甘，成为那段岁月的写照：“在我们国家，人们沉默不语。就好像我不存在，是个空白……做一个无用之人太难受了。我不想碌碌无为。我想完全填满生活，让生命完整。可我觉得局促，灵魂在身体里憋得慌，我需要一个容身之地。”在日记中，他多次记录与制片厂领导层的尖锐矛盾，尤其是与苏联国家电影委员会主席菲利普・叶尔马什的对立——叶尔马什梦想打造“苏维埃好莱坞”，偏爱擅长宏大叙事、创作立场鲜明的导演，而追求艺术本真、不向政治妥协的塔可夫斯基从未入他的眼。
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公安机关应当将传唤的原因和依据告知被传唤人。对无正当理由不接受传唤或者逃避传唤的人，经公安机关办案部门负责人批准，可以强制传唤。
Yet, until now, the United States never installed an outspoken vaccine critic like Robert F. Kennedy Jr. as a top health official with the power to upend federal childhood vaccine recommendations. Health and Human Services Secretary Kennedy and other top officials in the Trump administration have waged an “unprecedented attack on the nation’s evidence-based childhood immunization schedule,” a lawsuit, filed by 15 states, charged on Tuesday. Their actions will make people sicker and strain state resources, the suit claims.