阅读下面文字，筛选、整合相关信息，为“光活化农药”下一个定义。
20世纪初，人们研究了吖啶、荧光素等染料在光照下的杀虫作用。70年代，约荷等人又研究了卤代荧光素对家蝇的光动力作用，将光活化农药的研究推向一个新的高潮。研究中人们发现，一些物质平时并没有毒性，但进入生物体内以后在光诱导的作用下，会变得有毒，从而对家蝇、大蚁、象鼻虫等害虫起到毒害作用。这些物质还具有在自然界迅速降解为无害物质的特性，因此很适合制成农药。近年来，光活化农药的优点和应用前景正引起人们的广泛关注。
光活化农药是__________________________________________。
光活化农药是用某些平时无毒，但进人生物体后在光照下产生毒性，又可以迅速自然降解为无害物质的物质制成的一种杀虫药（农药）。（意对即可）
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| In a memory-based competition between you and a chimp(猩猩); who do you think would win? If you put yourself on top, you might want to guess again. In a test that challenged participants to remember numbers, a young chimp performed better than Japanese college students. Here's how the test worked. At Kyoto University in Japan, human students and chimpanzee participants sat in front of a computer. Five numbers, ranging from 1 to 9, were combined with one another and then, they appeared at random places on the screen. The numbers stayed on the screen for less than a second. In the first test, for example, participants saw the numbers for 650 milliseconds(about two-thirds of a second). Then, each number disappeared and they saw a white square instead. Participants had to touch the squares in numerical order, based on the numbers that had been there a moment before. In this test, the students touched the boxes in the correct order about 80 percent of the time. A young chimp named Ayumu performed equally well. During a harder test, participants were only able to see the numbers for 210 milliseconds. This time, students only succeeded in putting the boxes in the correct order about 40 percent of the time. But Ayumu still could select the boxes in the fight order nearly 80 percent of the time. Some people have what's called a "photographic memory," which allows them to remember a surprising number of details after just a quick glimpse of something. Ayumu's memory might work in a similar way says lead researcher Tetsuro Matsuzawa. The chimp's young age might have something to do with his impressive performance, too. In previous tests, the Japanese researchers found that young chimps performed better than their mothers. The scientists are interested to see whether Ayumu loses his strong memory as he grows older. They already know that young children sometimes have sharp memories when offered something photographical, but they lose this ability over time.
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