The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen.

最好的信号不仅取决于它的亮度，还取决于它与背景的对比度。

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CLIA using acridinium ester derivatives as chemiluminescent label has advantages of low background and high signal-to-noise ratio.

以吖啶酯衍生物为发光标记物的CLIA的特点是：自然本底低和信噪比高。

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The bright colors on the blue background indicate that an anomalous signal was received here on Earth by a radio telescope involved in a Search for Extraterrestrial Intelligence (SETI).

在蓝色背景上的明亮颜色表明在地球上收到了一个不寻常的信号，它来自于搜寻地外文明计划（SETI）的一台射电望远镜。

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The clock face, which uses a red second hand resembling a railway signal on a monochrome background, was designed for the SBB in 1944 by engineer and designer Hans Hilfiker while the rest of Europe was focusing on other matters.

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"His engagement would send a very strong signal to people who are wavering" that supporting expanded background checks would be, "if not a safe vote, then not as dangerous a vote as the conventional wisdom might hold, " said Kristin Goss, a professor at Duke University's Sanford School of Public Policy.

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We turned on a American Idol rerun just for background but it was frustrating to know that CSI was just one ATSC signal away, but we just could not watch it.

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