请登录

免费注册

首页购物车我的订单会员中心

联系客服

823711899

点击QQ咨询

400-618-9990

拨打电话咨询

购物车 0

上传BOM

产品分类

找货询价

QQ咨询

会员中心

购物车

技术支持

售后咨询

图片源于供应商或网络,实物可能存在差异,请以实物为准

5015KL-04W-B39-E00

价格阶梯

售价

折合1管

75+

¥ 396.035691

显示更多 ▼

购买数量

总价金额：￥ 29702.676825

加入购物车

立即购买

样品申购

详细描述：风扇

产品参数

产品属性	属性值
制造商	NMB Technologies Corporation
包装	盒
系列	-
零件状态	在售

PDF描述：风扇

暂无产品概述

购物指南

支付方式

配送服务

售后服务

发票须知

优惠券使用规则

代理产品

代理品牌

代理器件

特色服务

PCBA制造

国产品牌推荐

国产料号替代

质量保证

技术资料

行业资讯

关于我们

关于壹壹捌

联系我们

服务热线：400-618-9990

企业邮箱：sales@ic118.com

服务时间：周一至周六 8:30-17:30

壹壹捌官方微信号

PDF索引：

IC型号索引：

深圳网络警察报警平台

公共信息安全网络监察

经营性网站备案信息

不良信息举报中心

工商网监电子标识

全国公安机关备案

基本文件流程错误 SQL 调试用户

/www/wwwroot/www.ic72.com/public/index.php ( 0.79 KB )
/www/wwwroot/www.ic72.com/vendor/autoload.php ( 0.73 KB )
/www/wwwroot/www.ic72.com/vendor/composer/autoload_real.php ( 1.63 KB )
/www/wwwroot/www.ic72.com/vendor/composer/platform_check.php ( 1.01 KB )
/www/wwwroot/www.ic72.com/vendor/composer/ClassLoader.php ( 15.99 KB )
/www/wwwroot/www.ic72.com/vendor/composer/autoload_static.php ( 12.68 KB )
/www/wwwroot/www.ic72.com/vendor/ralouphie/getallheaders/src/getallheaders.php ( 1.60 KB )
/www/wwwroot/www.ic72.com/vendor/symfony/deprecation-contracts/function.php ( 0.99 KB )
/www/wwwroot/www.ic72.com/vendor/guzzlehttp/guzzle/src/functions_include.php ( 0.16 KB )
/www/wwwroot/www.ic72.com/vendor/guzzlehttp/guzzle/src/functions.php ( 5.55 KB )
/www/wwwroot/www.ic72.com/vendor/adbario/php-dot-notation/src/helpers.php ( 0.57 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/helper.php ( 8.34 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/stubs/load_stubs.php ( 0.16 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Exception.php ( 1.69 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Facade.php ( 2.71 KB )
/www/wwwroot/www.ic72.com/vendor/yansongda/supports/src/Functions.php ( 1.53 KB )
/www/wwwroot/www.ic72.com/vendor/hyperf/engine/src/Functions.php ( 0.83 KB )
/www/wwwroot/www.ic72.com/vendor/symfony/polyfill-mbstring/bootstrap.php ( 8.26 KB )
/www/wwwroot/www.ic72.com/vendor/symfony/polyfill-mbstring/bootstrap80.php ( 9.77 KB )
/www/wwwroot/www.ic72.com/vendor/yansongda/artful/src/Functions.php ( 2.38 KB )
/www/wwwroot/www.ic72.com/vendor/phpseclib/phpseclib/phpseclib/bootstrap.php ( 0.72 KB )
/www/wwwroot/www.ic72.com/vendor/symfony/var-dumper/Resources/functions/dump.php ( 1.49 KB )
/www/wwwroot/www.ic72.com/vendor/yansongda/pay/src/Functions.php ( 19.32 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/App.php ( 14.29 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Container.php ( 15.39 KB )
/www/wwwroot/www.ic72.com/vendor/psr/container/src/ContainerInterface.php ( 1.02 KB )
/www/wwwroot/www.ic72.com/app/provider.php ( 0.19 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Http.php ( 6.04 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/helper/Str.php ( 7.29 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Env.php ( 4.52 KB )
/www/wwwroot/www.ic72.com/app/common.php ( 107.36 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/helper.php ( 18.47 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Config.php ( 4.62 KB )
/www/wwwroot/www.ic72.com/config/api.php ( 0.59 KB )
/www/wwwroot/www.ic72.com/config/app.php ( 2.86 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/facade/Env.php ( 1.67 KB )
/www/wwwroot/www.ic72.com/config/cache.php ( 1.07 KB )
/www/wwwroot/www.ic72.com/config/console.php ( 0.37 KB )
/www/wwwroot/www.ic72.com/config/cookie.php ( 2.06 KB )
/www/wwwroot/www.ic72.com/config/database.php ( 5.02 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/facade/Config.php ( 1.37 KB )
/www/wwwroot/www.ic72.com/config/email.php ( 2.34 KB )
/www/wwwroot/www.ic72.com/config/filesystem.php ( 0.68 KB )
/www/wwwroot/www.ic72.com/config/lang.php ( 0.82 KB )
/www/wwwroot/www.ic72.com/config/log.php ( 1.35 KB )
/www/wwwroot/www.ic72.com/config/middleware.php ( 0.19 KB )
/www/wwwroot/www.ic72.com/config/payment.php ( 0.00 KB )
/www/wwwroot/www.ic72.com/config/route.php ( 1.54 KB )
/www/wwwroot/www.ic72.com/config/session.php ( 0.70 KB )
/www/wwwroot/www.ic72.com/config/trace.php ( 0.58 KB )
/www/wwwroot/www.ic72.com/config/view.php ( 0.96 KB )
/www/wwwroot/www.ic72.com/app/event.php ( 0.26 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Event.php ( 6.97 KB )
/www/wwwroot/www.ic72.com/app/service.php ( 0.13 KB )
/www/wwwroot/www.ic72.com/app/AppService.php ( 0.44 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Service.php ( 1.64 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Lang.php ( 7.22 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/lang/zh-cn.php ( 13.27 KB )
/www/wwwroot/www.ic72.com/app/lang/zh-cn.php ( 0.08 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/initializer/Error.php ( 3.27 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/initializer/RegisterService.php ( 1.33 KB )
/www/wwwroot/www.ic72.com/vendor/services.php ( 0.17 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/service/PaginatorService.php ( 1.52 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/service/ValidateService.php ( 0.99 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/service/ModelService.php ( 1.75 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-multi-app/src/Service.php ( 1.08 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-trace/src/Service.php ( 0.77 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Middleware.php ( 6.65 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/initializer/BootService.php ( 0.77 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/Paginator.php ( 11.71 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Validate.php ( 46.61 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/Model.php ( 26.86 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/Attribute.php ( 19.12 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/RelationShip.php ( 26.44 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/ModelEvent.php ( 2.58 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/TimeStamp.php ( 5.69 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/AutoWriteId.php ( 1.44 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/concern/Conversion.php ( 10.85 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/contract/Arrayable.php ( 0.09 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/contract/Jsonable.php ( 0.13 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Db.php ( 2.88 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/DbManager.php ( 8.33 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Log.php ( 6.27 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Manager.php ( 3.92 KB )
/www/wwwroot/www.ic72.com/vendor/psr/log/src/LoggerTrait.php ( 2.69 KB )
/www/wwwroot/www.ic72.com/vendor/psr/log/src/LoggerInterface.php ( 2.68 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Cache.php ( 4.91 KB )
/www/wwwroot/www.ic72.com/vendor/psr/simple-cache/src/CacheInterface.php ( 4.71 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/helper/Arr.php ( 16.08 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/cache/driver/File.php ( 7.60 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/cache/Driver.php ( 8.17 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/contract/CacheHandlerInterface.php ( 1.99 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Console.php ( 22.64 KB )
/www/wwwroot/www.ic72.com/app/Request.php ( 0.09 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Request.php ( 54.27 KB )
/www/wwwroot/www.ic72.com/app/middleware.php ( 0.32 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Pipeline.php ( 2.61 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-trace/src/TraceDebug.php ( 2.94 KB )
/www/wwwroot/www.ic72.com/app/middleware/AccessLog.php ( 2.59 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-multi-app/src/MultiApp.php ( 7.06 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Route.php ( 23.25 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/RuleName.php ( 5.31 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/Domain.php ( 5.53 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/RuleGroup.php ( 13.56 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/Rule.php ( 23.18 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/RuleItem.php ( 9.19 KB )
/www/wwwroot/www.ic72.com/route/app.php ( 0.77 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/facade/Route.php ( 4.68 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/dispatch/Url.php ( 3.42 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/dispatch/Controller.php ( 6.61 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/route/Dispatch.php ( 6.07 KB )
/www/wwwroot/www.ic72.com/app/controller/Stock.php ( 67.97 KB )
/www/wwwroot/www.ic72.com/app/controller/Api.php ( 13.19 KB )
/www/wwwroot/www.ic72.com/app/BaseController.php ( 2.04 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/facade/Db.php ( 0.93 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/connector/Mysql.php ( 4.33 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/PDOConnection.php ( 51.60 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/Connection.php ( 8.79 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/ConnectionInterface.php ( 4.86 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/builder/Mysql.php ( 16.56 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/Builder.php ( 22.26 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/BaseBuilder.php ( 27.29 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/Query.php ( 15.19 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/BaseQuery.php ( 41.48 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/TimeFieldQuery.php ( 7.43 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/AggregateQuery.php ( 3.26 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/ModelRelationQuery.php ( 19.29 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/ParamsBind.php ( 3.66 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/ResultOperation.php ( 6.98 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/Transaction.php ( 2.77 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/WhereQuery.php ( 18.79 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/JoinAndViewQuery.php ( 6.96 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/concern/TableFieldInfo.php ( 2.46 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/log/driver/File.php ( 6.17 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/contract/LogHandlerInterface.php ( 0.86 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/log/Channel.php ( 3.88 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/event/LogRecord.php ( 0.86 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/facade/Cookie.php ( 1.48 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Cookie.php ( 5.97 KB )
/www/wwwroot/www.ic72.com/app/model/Type.php ( 0.45 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/model/Collection.php ( 6.96 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-helper/src/Collection.php ( 16.48 KB )
/www/wwwroot/www.ic72.com/app/model/Cart.php ( 15.85 KB )
/www/wwwroot/www.ic72.com/app/model/Api.php ( 11.18 KB )
/www/wwwroot/www.ic72.com/app/controller/Index.php ( 24.67 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/facade/View.php ( 1.70 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/View.php ( 4.33 KB )
/www/wwwroot/www.ic72.com/app/model/Stock.php ( 64.65 KB )
/www/wwwroot/www.ic72.com/app/model/StockPra.php ( 0.78 KB )
/www/wwwroot/www.ic72.com/app/model/StockPrice.php ( 1.52 KB )
/www/wwwroot/www.ic72.com/app/model/StockUnit.php ( 0.78 KB )
/www/wwwroot/www.ic72.com/app/model/StockWarehouse.php ( 0.91 KB )
/www/wwwroot/www.ic72.com/app/model/Pdf.php ( 3.09 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-orm/src/db/Raw.php ( 1.22 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-view/src/Think.php ( 8.00 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-template/src/Template.php ( 46.61 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-template/src/template/driver/File.php ( 2.41 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-template/src/template/contract/DriverInterface.php ( 0.86 KB )
/www/wwwroot/www.ic72.com/runtime/temp/995a9576ac15c40d17b616c95da56580.php ( 96.98 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/Response.php ( 8.65 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/framework/src/think/response/Html.php ( 0.97 KB )
/www/wwwroot/www.ic72.com/vendor/topthink/think-trace/src/Html.php ( 4.49 KB )

CONNECT:[ UseTime:0.000703s ] mysql:host=127.0.0.1;port=3306;dbname=ic72com;charset=utf8
SHOW FULL COLUMNS FROM `visit_log` [ RunTime:0.002120s ]
INSERT INTO `visit_log` SET `ip` = '216.73.217.46' , `useragent` = 'Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)' , `reffer` = '' , `host` = 'https://www.ic118.com/stock/detail&id=33069342' [ RunTime:0.002397s ]
SHOW FULL COLUMNS FROM `product_type` [ RunTime:0.002182s ]
SELECT `id`,`typeid`,`name`,`typestr` FROM `product_type` WHERE `id` NOT IN (11,12,13,14,15) AND `id` <= 750 [ RunTime:0.000587s ]
SHOW FULL COLUMNS FROM `o_cart` [ RunTime:0.003231s ]
SELECT COUNT(*) AS think_count FROM `o_cart` WHERE ( `userId` = 0 AND `visitIP` = '216.73.217.46' ) [ RunTime:0.008328s ]
SHOW FULL COLUMNS FROM `ad` [ RunTime:0.002127s ]
SELECT * FROM `ad` WHERE `isDisplay` = 1 [ RunTime:0.008973s ]
SHOW FULL COLUMNS FROM `stock` [ RunTime:0.002539s ]
SELECT `s`.*,`u`.`company`,`t`.`name` FROM `stock` `s` LEFT JOIN `user` `u` ON `u`.`id`=`s`.`userid` LEFT JOIN `product_type` `t` ON `t`.`id`=`s`.`categoryid` WHERE `s`.`id` = '33069342' LIMIT 1 [ RunTime:0.009678s ]
SHOW FULL COLUMNS FROM `stock_pra` [ RunTime:0.002465s ]
SELECT * FROM `stock_pra` WHERE `stockid` = 33069342 [ RunTime:0.002699s ]
SHOW FULL COLUMNS FROM `stock_price` [ RunTime:0.002103s ]
SELECT * FROM `stock_price` WHERE `stockid` = 33069342 ORDER BY `minOrder` ASC [ RunTime:0.004081s ]
SHOW FULL COLUMNS FROM `stock_unitquantity` [ RunTime:0.002926s ]
SELECT * FROM `stock_unitquantity` WHERE `stockid` = 33069342 ORDER BY `unit` DESC [ RunTime:0.003510s ]
SHOW FULL COLUMNS FROM `stock_warehousequantity` [ RunTime:0.003440s ]
SELECT * FROM `stock_warehousequantity` WHERE `stockid` = 33069342 [ RunTime:0.005683s ]
SELECT `name` FROM `product_type` WHERE `id` = 0 LIMIT 1 [ RunTime:0.006717s ]
SELECT * FROM `stock_price` WHERE `stockid` = 33069342 ORDER BY `minOrder` ASC [ RunTime:0.006478s ]
CONNECT:[ UseTime:0.000872s ] mysql:host=127.0.0.1;port=3306;dbname=ic72com_pdf;charset=utf8
select * from pdf where partno='5015KL-04W-B39-E00' and brandshort='NMB Technologies Corporation' limit 1 [ RunTime:0.018195s ]
SHOW FULL COLUMNS FROM `pdf` [ RunTime:0.002634s ]
SELECT `id`,`partno`,`note`,`note_cn` FROM `pdf` WHERE `partno` = '5015KL-04W-B39-E00' LIMIT 1 [ RunTime:0.016306s ]
SHOW FULL COLUMNS FROM `stock_pra_lib` [ RunTime:0.002963s ]
SELECT `pra` FROM `stock_pra_lib` WHERE ( ( `partno` = '5015KL-04W-B39-E00' OR `brand` LIKE 'NMB Technologies Corporation%' ) ) LIMIT 1 [ RunTime:0.003683s ]
SELECT `id` FROM `stock` WHERE `id` <> 33069342 AND `partno` = '5015KL-04W-B39-E00' AND `lockUser` = 0 AND ( LOWER(brand) LIKE '%nmb technologies corporation%' ) [ RunTime:0.003956s ]
SELECT * FROM `stock_pra` WHERE `stockid` = 18593312 [ RunTime:0.000976s ]
SELECT `note` FROM `stock` WHERE `id` = 18593312 LIMIT 1 [ RunTime:0.009297s ]
SELECT `description` FROM `stock` WHERE `id` = 18593312 LIMIT 1 [ RunTime:0.017058s ]
SHOW FULL COLUMNS FROM `icreplace` [ RunTime:0.004470s ]
SELECT `r`.*,`b`.`brandshort`,`b`.`brandcn` FROM `icreplace` `r` LEFT JOIN `stock_brand` `b` ON `b`.`id`=`r`.`icbrandid` WHERE `r`.`partno` = '5015KL-04W-B39-E00' ORDER BY `r`.`id` DESC LIMIT 5 [ RunTime:0.021876s ]

0.411951s

5015KL-04W-B39-E00

购买数量

总价金额： ￥ 29702.676825

推荐替代

详细描述：风扇

产品参数

PDF描述： 风扇

总价金额：￥ 29702.676825

PDF描述：风扇