名校
1 . 化学平衡是指在一定条件下,可逆反应的正反应速率和逆反应速率相等时,体系所处的状态.根据计算系统的吉布斯自由能变化
的热力学公式Gibbs-Helmholtz方程和Van’tHoff方程,可以得到温度
与可逆反应的平衡常数
的关系式:
式中
为焓变(在一定温度变化范围内视为定值),
为熵变,R为气体常数.利用上述公式,我们可以处理不同温度下,有关多重可逆反应的平衡常数之间关系的计算.已知当温度为
时,可逆反应的平衡常数为
;当温度为
时,可逆反应的平衡常数为
.则
( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3c46bf5416873a5a9c22e240b7ef4ddc.png)
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2 . 新冠疫情防控常态化,核酸检测应检尽检!核酸检测分析是用荧光定量
法,通过化学物质的荧光信号,对在
扩增进程中成指数级增加的靶标
实时检测,在
扩增的指数时期,荧光信号强度达到阈值时,
的数量
与扩增次数
满足:
,其中
为扩增效率,
为
的初始数量.已知某被测标本
扩增5次后,数量变为原来的10倍,那么该标本的扩增效率
约为( )(参考数据:
,
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab8a2c4e50f3a0318a3ef4aa89ed4eab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ab8a2c4e50f3a0318a3ef4aa89ed4eab.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/59b98020deb38157a0d38373b6c822a9.png)
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A.0.369 | B.0.415 | C.0.585 | D.0.631 |
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3 . 从
到
通信,网络速度提升了
倍.其中,香农公式
是被广泛公认的通信理论基础和研究依据,它表示:在受噪声干扰的信道中,最大信息传递率
取决于信道带宽
、信道内信号的平均功率
、信道内部的高斯噪声功率
的大小,其中
叫做信噪比.根据香农公式,以下说法正确的是__________ .
①若不改变信噪比
,而将信道带宽
增加一倍,则
增加一倍;
②若不改变信道带宽
和信道内信号的平均功率
,而将高斯噪声功率
降低为原来的一半,则
增加一倍;
③若不改变带宽
,而将信噪比
从
提升至
,
增加了
;
④若不改变带宽
,而将信噪比
从
提升至
,
大约增加了
.(参考数据:
)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e1bea758006164d7d614c230243e10e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/47248d88a8876e1177cbd3ba43b11bea.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b72ac611ae66b86761e080761d9aabc.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b629d0b15ee3a7d3123bd63b722b51fd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91edc7e2d4811f5ea6c01284cf00393a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60c91fa27331e9958df48fd5633432e4.png)
①若不改变信噪比
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60c91fa27331e9958df48fd5633432e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91edc7e2d4811f5ea6c01284cf00393a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
②若不改变信道带宽
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91edc7e2d4811f5ea6c01284cf00393a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cf231f8f86fb922df4ca0c87f044cec3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
③若不改变带宽
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91edc7e2d4811f5ea6c01284cf00393a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60c91fa27331e9958df48fd5633432e4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d13d3dba8d3376f684c3ff8c9a10c726.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1d525d7572797092de16f9b4724da7c7.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3e2fa2c62d988b9c016b77a1f4be70e9.png)
④若不改变带宽
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/91edc7e2d4811f5ea6c01284cf00393a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60c91fa27331e9958df48fd5633432e4.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f4500e95a6c2a77e0ccb418518c3f6c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/030e7e934455277a8f3c7763a3a2226f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ec074b5edcfb70d7c3a3c9fb17a721e.png)
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3卷引用:北京市石景山区2021届高三上学期数学期末试题
北京市石景山区2021届高三上学期数学期末试题(已下线)专题9.3 期中押题检测卷(考试范围:第1-4章)3(难)【满分计划】2021-2022学年高一数学阶段性复习测试卷(苏教版2019必修第一册)重庆市求精中学2021-2022学年高一上学期第二次月考数学试题
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4 . 渔民出海打鱼,为了保证获得的鱼新鲜,鱼被打上船后,要在最短的时间内将其分拣、冷藏,若不及时处理,打上来的鱼会很快失去新鲜度.已知某种鱼失去的新鲜度
与其出水后时间
(分)满足的函数关系式为
.若出水后
分钟,这种鱼失去的新鲜度为
,出水后
分钟,这种鱼失去的新鲜度为
.那么若不及时处理,打上来的这种鱼在多长时间后开始失去全部新鲜度(已知
,结果取整数)( )
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3eabd5f3a86afe49dcd70571e2b96cfd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36a1b09c653185842513e24ebba60bb3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6fba21bd28c91c57d2564dd7e4980b74.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d07ae0b4264da6a8812454ffd2f20d94.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3de0640bc12a9b2ffd7247fa20f1dafd.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/23466fd31d0666cb9f65dced41188359.png)
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河北省衡水市冀州区第一中学2021届高三上学期期末数学试题(已下线)黄金卷12-【赢在高考·黄金20卷】备战2021年高考数学全真模拟卷(山东高考专用)(已下线)必刷卷04-2021年高考数学考前信息必刷卷(江苏专用)湖北省武汉市华中师大一附中2020-2021学年高三上学期期中数学试题(已下线)第2讲 基本初等函数、函数与方程(讲)-2022年高考数学二轮复习讲练测(新教材·新高考地区专用)