下载百度汉语App

名师好课免费看

梦秦氏赠言

【作者】曹雪芹【朝代】清

拼音

{"ret_array":[{"shangxi_ext":[],"type":["poem"],"means_kv_list":[],"literature_author":[{"people_height":[""],"people_family_members":[],"people_sex":["\u7537"],"show":[""],"people_yingshizuoping":[],"dynasty":[""],"people_measurement":[""],"baike_url":[],"display_name":["\u66f9\u96ea\u82b9"],"people_teacher":[""],"id":["7592e34d337c48c8aad1b24b97cb122e"],"basic_tag":["\u4e2d\u56fd\u6587\u5b66","\u7ea2\u697c\u68a6","\u6587\u5b66\u5bb6","\u5c0f\u8bf4\u5bb6","\u56db\u5927\u540d\u8457"],"basic_name_chs":["\u66f9\u96ea\u82b9"],"people_graduate_school":[""],"basic_sublemmtitle":["\u6e05\u4ee3\u5c0f\u8bf4\u5bb6"],"source":[""],"people_weight":[""],"baike_id":["14919"],"people_blood_type":[""],"people_active_state":["\u4e2d\u56fd"],"people_young_brother":[""],"mtime":["1593682578928"],"people_hao":[],"people_young_sister":[""],"name":["\u66f9\u96ea\u82b9"],"baike_name":["\u66f9\u96ea\u82b9"],"basic_aliasname":["\u82b9\u6eaa","\u96ea\u82b9","\u82b9\u5703","\u66f9\u6cbe","\u82b9\u6eaa\u5c45\u58eb","\u66f9\u82b9\u6eaa"],"real_name":["\u66f9\u96ea\u82b9"],"sid":["7592e34d337c48c8aad1b24b97cb122e"],"basic_piclink":["http:\/\/t11.baidu.com\/it\/u=3027739840,748335441&fm=58","http:\/\/t11.baidu.com\/it\/u=1774174162,3939489204&fm=58","http:\/\/t11.baidu.com\/it\/u=3264135469,3705867750&fm=58","http:\/\/t11.baidu.com\/it\/u=2687455336,2470060605&fm=58"],"people_relationactor":[],"people_son":[],"ts":["1593682578928"],"people_sister":[""],"people_monicker":[""],"voiceactor_of_video":[],"basic_classification":["\u6587\u5316\u4eba\u7269","\u4eba\u7269","\u5c0f\u8bf4\u5bb6"],"people_friend":[],"people_wife":[""],"people_specialty":[""],"name_pinyin":["c\u00e1o xu\u011b q\u00edn"],"people_xiangnian":[""],"basic_description":["\u66f9\u96ea\u82b9\uff0c\u540d\u6cbe\uff0c\u5b57\u68a6\u962e\uff0c\u53f7\u96ea\u82b9\uff0c\u53c8\u53f7\u82b9\u6eaa\u3001\u82b9\u5703\u3002\u6e05\u4ee3\u8457\u540d\u6587\u5b66\u5bb6\uff0c\u5c0f\u8bf4\u5bb6\u3002\u5148\u7956\u4e3a\u4e2d\u539f\u6c49\u4eba\uff0c\u6ee1\u6d32\u6b63\u767d\u65d7\u5305\u8863\u51fa\u8eab\u3002\u7d20\u6027\u653e\u8fbe\uff0c\u66fe\u8eab\u6742\u4f18\u4f36\u800c\u88ab\u94a5\u7a7a\u623f\u3002\u7231\u597d\u7814\u7a76\u5e7f\u6cdb\uff1a\u91d1\u77f3\u3001\u8bd7\u4e66\u3001\u7ed8\u753b\u3001\u56ed\u6797\u3001\u4e2d\u533b\u3001\u7ec7\u8865\u3001\u5de5\u827a\u3001\u996e\u98df\u7b49\u3002\u4ed6\u51fa\u8eab\u4e8e\u4e00\u4e2a\u201c\u767e\u5e74\u671b\u65cf\u201d\u7684\u5927\u5b98\u50da\u5730\u4e3b\u5bb6\u5ead\uff0c\u56e0\u5bb6\u5ead\u7684\u8870\u8d25\u9971\u5c1d\u4eba\u4e16\u8f9b\u9178\uff0c\u540e\u4ee5\u575a\u97e7\u4e0d\u62d4\u4e4b\u6bc5\u529b\uff0c\u5386\u7ecf\u591a\u5e74\u8270\u8f9b\u521b\u4f5c\u51fa\u6781\u5177\u601d\u60f3\u6027\u3001\u827a\u672f\u6027\u7684\u4f1f\u5927\u4f5c\u54c1\u300a\u7ea2\u697c\u68a6\u300b\u3002"],"basic_piclink_old":["http:\/\/imgsrc.baidu.com\/baike\/pic\/item\/3c6d55fbb2fb431696ab756022a4462309f7d370.jpg","http:\/\/img3.douban.com\/img\/celebrity\/large\/12836.jpg","http:\/\/hiphotos.baidu.com\/zhixin\/pic\/item\/3853ad1bb051f819098a6bb8dbb44aed2f73e752.jpg","http:\/\/hiphotos.baidu.com\/zhixin\/pic\/item\/78701455b319ebc4f166d40b8326cffc1f1716c2.jpg"],"people_zodiac":[""],"gushiwen_pv":["13351"],"people_age":[""],"people_birth_die":["1715 \u81f3 1763"],"people_yundongxiangmu":[""],"people_xueli":[""],"basic_originalname":[],"director_of_video":[],"people_dynasty":[],"people_zi":[],"people_nianhao":[],"people_deathplace":[""],"people_guojiadiqu":[""],"people_disciple":[""],"people_religion":[""],"people_constellation":[""],"people_spouse":[],"people_mother":[""],"people_unit":[""],"people_career":["\u5c0f\u8bf4\u5bb6","\u7f16\u5267"],"people_representative_work":["\u7ea2\u697c\u68a6"],"people_works":["\u7ea2\u697c\u68a6"],"people_relationrole":["\u66f9\u96ea\u82b9_\u5eb9\u5b97\u534e_\u66f9\u96ea\u82b9"],"pv":[13351],"cate":["\u4f5c\u8005"],"people_province":["\u6c5f\u82cf","\u8fbd\u5b81","\u6cb3\u5317"],"basic_system":["\u533b\u5fb7\u9ad8\u5c1a","\u5434\u627f\u6069","\u77ff\u7269","eference@@10","\u65b0\u5b89\u540f","\u6c49\u65cf\u8bf4","\u4e7e\u9686\u5e74\u8868\u4e2d","\u5173\u7fbd\u522e\u9aa8\u7597\u6bd2","\u66f9\u6cbe","\u4e0e\u5e7f\u6cc9\u5bfa","\u7ea2\u697c\u68a6\u7684\u6545\u4e8b","\u66f9\u82b9\u6eaa","5586","\u66f9\u96ea\u82b9--\u4e2d\u56fd\u53e4\u5178\u5c0f\u8bf4\u5de8\u5320","\u7578\u7b0f\u53df","\u76f8\u5173\u4eba\u7269","\u4eba\u7269\u7b80\u4ecb","eference@@7","\u6b66\u9633\u8bf4","\u4e7e\u9686\u5e74\u8868\u4e0b","\u4e7e\u9686\u5e74\u8868\u4e0a","\u675c\u752b","\u660e\u6e05\u5bab\u85cf\u5730\u9707\u6863\u6848","\u5434\u656c\u6893","\u65cf\u5c5e\u8fa8\u6790","\u66f9\u96ea\u82b9\u5893\u7891\u62d3\u672c","\u6866\u53f6\u8ff0\u95fb","\u6e05\u4ee3\u5c0f\u8bf4\u5bb6","\u674e\u56fd\u79cb","\u4e73\u5c71\u8bf4","\u6c49\u65cf","\u66f9\u96ea\u82b9","\u7ea2\u697c\u68a6\u65b0\u8bc1","\u7ea2\u697c\u68a6","\u6587\u5b66\u5bb6","\u8eab\u4e16\u7c4d\u8d2f","\u7edb\u8605\u79cb\u5e8f","\u4f3d\u5229\u7565\u00b7\u4f3d\u5229\u96f7","\u5bb6\u65cf\u6e0a\u6e90","\u4e09\u56fd\u6f14\u4e49","\u751f\u5e73\u5e74\u8868\u8d44\u6599\u6765\u6e90","\u9c81\u8fc5","\u5df4\u5c14\u624e\u514b","\u53f2\u8fdb","\u6797\u9edb\u7389","\u5224\u8bcd","\u94b1\u8d77","\u7eaa\u5ff5\u5c55\u9986","\u5c24\u4e09\u59d0","\u540d\u5b57\u7531\u6765","\u5218\u4e49\u5e86","\u6c34\u6d52\u4f20","UPDATE","\u9646\u539f","\u4e2d\u56fd\u6587\u5b66","\u9ad8\u9e57","6213182","\u4e2d\u6587\u540d\\t\u66f9\u6cbe\u522b\u540d\\t\u96ea\u82b9\u3001\u82b9\u5703\u3001\u82b9\u6eaa\u3001\u82b9\u6eaa\u5c45\u58eb\u56fd\u7c4d\\t\u6e05\u6c11\u65cf\\t\u6c49\u65cf\u51fa\u751f\u5730\\t\u6c5f\u5b81\uff08\u4eca\u6c5f\u82cf\u5357\u4eac\uff09\u51fa\u751f\u65e5\u671f\\t\u5eb7\u7199\u4e94\u5341\u56db\u5e74\u3001\u96cd\u6b63\u4e8c\u5e74\u901d\u4e16\u65e5\u671f\\t\u58ec\u5348\u9664\u5915\u3001\u7678\u672a\u9664\u5915\u3001\u7532\u7533\u521d\u6625\u804c\u4e1a\\t\u5c0f\u8bf4\u5bb6\u4e3b\u8981\u6210\u5c31\\t\u521b\u4f5c\u300a\u7ea2\u697c\u68a6\u300b\u4ee3\u8868\u4f5c\u54c1\\t\u300a\u7ea2\u697c\u68a6\u300b\u65d7\u7c4d\\t\u6ee1\u6d32\u6b63\u767d\u65d7\u7956\u7c4d\\t\u6cb3\u5317\u4e30\u6da6\u3001\u8fbd\u5b81\u94c1\u5cad\u3001\u8fbd\u5b81\u8fbd\u9633","\u751f\u5e73","\u8bd7\u4eba","\u846c\u82b1","\u57fa\u672c\u60c5\u51b5","\u6570\u4f4d\u8868","\u8102\u6279","\u5173\u6c49\u537f","\u6770\u5f17\u96f7\u00b7\u4e54\u53df","\u8eab\u4e16\u8003\u8bc1","\u4f3d\u5229\u7565\u536b\u661f","\u864e\u95e8\u7ecf\u5386","\u4e0e\u767d\u5bb6\u7583","\u4e9a\u91cc\u58eb\u591a\u5fb7","\u7a7a\u7a7a\u9053\u4eba","\u6e05\u4eba\u7b14\u8bb0\u8bb0\u95fb","\u516b\u65d7\u753b\u5f55","\u5f20\u5b9c\u6cc9","\u96cd\u6b63\u5e74\u8868","\u9999\u83f1\u5b66\u8bd7","ADD","\u56db\u5927\u540d\u8457","\u9898\u7ea2\u697c\u68a6","5957","\u5c0f\u8bf4\u521b\u4f5c","\u6566\u8bda","eference@@9","\u7ea6\u7ff0\u00b7\u6c83\u5c14\u592b\u5188\u00b7\u51af\u00b7\u6b4c\u5fb7","\u8463\u592a\u540e","\u5415\u4e91\u6240","\u7f57\u8d2f\u4e2d","\u4f20\u8bf4\u4e8b\u8ff9","\u5f20\u5927\u590d","\u968f\u56ed\u8bd7\u8bdd","1","\u540d\u8457","\u8fbd\u9633\u7eaa\u5ff5\u9986\u66f9\u96ea\u82b9\u5750\u50cf\u6765\u6e90","\u9676\u6e0a\u660e","\u5217\u592b\u00b7\u5c3c\u53e4\u62c9\u8036\u7ef4\u5947\u00b7\u6258\u5c14\u65af\u6cf0","\u5c0f\u8bf4\u5bb6","\u65bd\u8010\u5eb5","\u4eba\u7269","\u67a3\u7a97\u95f2\u7b14","\u7c73\u5f00\u6717\u57fa\u7f57","\u542c\u7956\u8f88\u4eec\u8bb2\u66f9\u96ea\u82b9\u7684\u6545\u4e8b","\u5eb7\u7199\u5e74\u8868","\u88ab\u201c\u6ee1\u65cf\u201d\u7684\u66f9\u96ea\u82b9","\u66f9\u96ea\u82b9\u751f\u5352\u846c\u5730\u7c4d\u8d2f\u6210\u8c1c","\u6ee1\u65cf\u8bf4","\u53cb\u4eba\u76f8\u5173\u8bd7\u4f5c","1706291","\u6566\u654f"],"people_sourcefrom":[""],"people_residence":[""],"people_living_time":[""],"trust":["1593682578928"],"people_ancestralhome":["\u6cb3\u5317\u4e30\u6da6"],"basic_name":["\u66f9\u96ea\u82b9"],"basic_source_url":["https:\/\/baike.baidu.com\/item\/%E6%9B%B9%E9%9B%AA%E8%8A%B9\/14919"],"people_nationality":[],"people_designation":[],"type":["author"],"people_hobby":[],"people_parents":[],"people_marital_status":[""],"people_native_place":["\u6cb3\u5317\u4e30\u6da6"],"tag":[],"people_birthday":[""],"whether_show_author":["1"],"people_sibling":[],"people_children":[],"cts":["1571635476441"],"people_deathday":[""],"people_brother":[],"people_yundongdui":[""],"people_jobposition":[""],"author_of_video":[""],"basic_foreignname":["Tsao Hsueh-Chin"],"people_nation":["\u6c49\u65cf"],"dts":["1593682578928"],"people_politics_status":[""],"update_time":[""],"people_husband":[""],"people_birthplace":["\u6c5f\u5b81\uff08\u4eca\u6c5f\u82cf\u5357\u4eac\uff09"],"people_lingmu":[""],"people_father":[""],"people_shihao":[""],"people_templename":[],"people_team":[""],"people_position":[],"sect":[""],"people_brokerage_company":[""],"people_faith":[],"people_old_brother":[],"baike_video":["https:\/\/tiku-data.cdn.bcebos.com\/hanyuvideo\/author\/7592e34d337c48c8aad1b24b97cb122e.mp4?auth_key=2318653097-0-0-acdcf5c1ad7fc7a4af4b61f43faa1e1d"],"baike_video_cover":["https:\/\/edu-public.cdn.bcebos.com\/hanyucover\/author\/7592e34d337c48c8aad1b24b97cb122e"],"_score":1}],"about":[],"form_type":["\u8bd7","\u53e4\u4ee3\u8bd7"],"voice_info":[],"body":["\u4e09\u6625\u53bb\u540e\u8bf8\u82b3\u5c3d\uff0c\u5404\u81ea\u987b\u5bfb\u5404\u81ea\u95e8\u3002"],"display_name":["\u68a6\u79e6\u6c0f\u8d60\u8a00"],"basic_source_url":["http:\/\/m.shicimingju.com\/chaxun\/list\/46051.html"],"baike_name":[""],"beautiful_line":[],"zhushi":[],"poemlines":[{"paragraph":1,"long_pos":0,"is_important":"1","short_pos":0,"pinyin":"s\u0101n ch\u016bn q\u00f9 h\u00f2u zh\u016b f\u0101ng j\u01d0n","gushiwen_pv":0,"pv":158,"name":"\u4e09\u6625\u53bb\u540e\u8bf8\u82b3\u5c3d","web_pv":158,"start_pos":0,"punc":"\uff0c"},{"paragraph":1,"long_pos":0,"is_important":"1","short_pos":1,"pinyin":"g\u00e8 z\u00ec x\u016b x\u00fan g\u00e8 z\u00ec m\u00e9n","gushiwen_pv":0,"pv":58,"name":"\u5404\u81ea\u987b\u5bfb\u5404\u81ea\u95e8","web_pv":58,"start_pos":8,"punc":"\u3002"}],"zhushi_kv_list":[],"dynasty":["\u6e05"],"background":[],"name":[{"is_important":"2","@value":"\u68a6\u79e6\u6c0f\u8d60\u8a00"}],"poem_format":[""],"baike_id":["8603237"],"shangxi":[{"link":"http:\/\/m.shicimingju.com\/chaxun\/list\/46051.html","text":"\u3010\u6ce8\u91ca\u3011\uff1a[\u8bc4\u4ecb]\u8fd9\u662f\u79e6\u53ef\u537f\u4e34\u6b7b\u524d\u5728\u7ed9\u51e4\u59d0\u6258\u7684\u68a6\u4e2d\u7559\u4e0b\u7684\u6700\u540e\u8d60\u8a00\u3002\u5b83\u9884\u793a\u7740\u8d3e\u5e9c\u76db\u6781\u800c\u8870\uff0c\u6811\u5012\u7322\u72f2\u6563\u7684\u7ed3\u5c40\u3002\u79e6\u53ef\u537f\u4e3a\u8fd9\u4e2a\u5373\u5c06\u5d29\u6e83\u7684\u5927\u5bb6\u65cf\u7b56\u5212\u540e\u4e8b\uff0c\u5b89\u6392\u9000\u8def\u3002\u5979\u544a\u8beb\u51e4\u59d0\uff1a\u201c\u8981\u77e5\u9053\uff0c\u4e5f\u4e0d\u8fc7\u662f\u77ac\u606f\u7684\u7e41\u534e\uff0c\u4e00\u65f6\u7684\u6b22\u4e50\uff0c\u4e07\u4e0d\u53ef\u5fd8\u4e86\u90a3\u2018\u76db\u7b75\u5fc5\u6563\u2019\u7684\u4fd7\u8bed\u3002\u6b64\u65f6\u82e5\u4e0d\u65e9\u4e3a\u540e\u8651\uff0c\u4e34\u671f\u53ea\u6050\u540e\u6094\u65e0\u76ca\u4e86\u3002\u201d\u5b9e\u9645\u4e0a\u8fd9\u53ea\u4e0d\u8fc7\u662f\u79e6\u53ef\u537f\u7684\u4e00\u79cd\u613f\u671b\u548c\u5e7b\u60f3\uff0c\u5c01\u5efa\u793e\u4f1a\u7684\u8870\u843d\u662f\u5386\u53f2\u53d1\u5c55\u7684\u5fc5\u7136\u89c4\u5f8b\uff0c\u90a3\u662f\u65ad\u7136\u4e0d\u80fd\uff0c\u4e5f\u662f\u65e0\u6cd5\u201c\u7597\u7ee7\u201d\u7684\u3002 ","source":"\u8bd7\u8bcd\u540d\u53e5\u7f51"}],"columbus":["0"],"sid":["29ad218633ba2bd6a6dcb51e7f7711a4"],"align":"left"}],"extra":{"entity-num":1,"return-num":1},"related_poems":[{"sid":"ce790335f57411e5a538c8e0eb15ce01","name":"\u846c\u82b1\u541f","author":"\u66f9\u96ea\u82b9","dynasty":"\u6e05"},{"sid":"ce7a86fdf57411e5a2b2c8e0eb15ce01","name":"\u4e94\u7f8e\u541f\u00b7\u897f\u65bd","author":"\u66f9\u96ea\u82b9","dynasty":"\u6e05"},{"sid":"ce77e775f57411e5984dc8e0eb15ce01","name":"\u7ec8\u8eab\u8bef","author":"\u66f9\u96ea\u82b9","dynasty":"\u6e05"},{"sid":"0e96370c78884eb0b52ecbf015cf7c94","name":"\u4ee3\u522b\u79bb\u00b7\u79cb\u7a97\u98ce\u96e8\u5915","author":"\u66f9\u96ea\u82b9","dynasty":"\u6e05"},{"sid":"ce7af285f57411e5a9d2c8e0eb15ce01","name":"\u8299\u84c9\u5973\u513f\u8bd4","author":"\u66f9\u96ea\u82b9","dynasty":"\u6e05"}],"recommend_poems":[{"sid":"5069e2eea3d84fd3a7f13871c578638f","name":"\u5929\u51c0\u6c99\u00b7\u79cb\u601d","author":"\u9a6c\u81f4\u8fdc","dynasty":"\u5143"},{"sid":"50a1f9619dd0a5384146462d5e14a4d8","name":"\u4e00\u4e2a\u6df1\u591c\u7684\u8bb0\u5fc6","author":"\u9c81\u85dc","dynasty":"\u73b0\u4ee3"},{"sid":"d68bb774aa644f37a101a2fc3197bc82","name":"\u6625\u671b","author":"\u675c\u752b","dynasty":"\u5510"},{"sid":"7ce02b8ee97749d7b691f2cdaeec4675","name":"\u7edd\u53e5","author":"\u675c\u752b","dynasty":"\u5510"},{"sid":"20d94c03f5efc5b91998ae506cc65487","name":"\u79cb\u9882","author":"\u6d4e\u6148","dynasty":"\u73b0\u4ee3"}],"pinyin_means_kv_list":{"pinyin_translate_flag":0,"pinyin_info":[[{"punc":"\uff0c","details":[{"ziList":[{"pinyin":"s\u0101n","text":"\u4e09"}],"zhushi":""},{"ziList":[{"pinyin":"ch\u016bn","text":"\u6625"}],"zhushi":""},{"ziList":[{"pinyin":"q\u00f9","text":"\u53bb"}],"zhushi":""},{"ziList":[{"pinyin":"h\u00f2u","text":"\u540e"}],"zhushi":""},{"ziList":[{"pinyin":"zh\u016b","text":"\u8bf8"}],"zhushi":""},{"ziList":[{"pinyin":"f\u0101ng","text":"\u82b3"}],"zhushi":""},{"ziList":[{"pinyin":"j\u01d0n","text":"\u5c3d"}],"zhushi":""}],"translate":null},{"punc":"\u3002","details":[{"ziList":[{"pinyin":"g\u00e8","text":"\u5404"}],"zhushi":""},{"ziList":[{"pinyin":"z\u00ec","text":"\u81ea"}],"zhushi":""},{"ziList":[{"pinyin":"x\u016b","text":"\u987b"}],"zhushi":""},{"ziList":[{"pinyin":"x\u00fan","text":"\u5bfb"}],"zhushi":""},{"ziList":[{"pinyin":"g\u00e8","text":"\u5404"}],"zhushi":""},{"ziList":[{"pinyin":"z\u00ec","text":"\u81ea"}],"zhushi":""},{"ziList":[{"pinyin":"m\u00e9n","text":"\u95e8"}],"zhushi":""}],"translate":null}]]},"ad":{"banner":[],"text":[]},"suggestion":["\u674e\u767d\u7684\u8bd7","aabb\u5f0f\u7684\u8bcd\u8bed","\u518d\u522b\u5eb7\u6865","\u665f\u7684\u62fc\u97f3","\u72b9\u8c6b\u7684\u8fd1\u4e49\u8bcd","\u6625\u534e\u79cb\u5b9e","\u63cf\u5199\u6625\u5929\u7684\u53e4\u8bd7","\u542b\u6709\u5f00\u7684\u6210\u8bed","\u4e0d\u8fa8\u83fd\u7c9f"],"userImage":null}

sān

三

chūn

春

qù

去

hòu

后

zhū

诸

fāng

芳

jǐn

尽

，

gè

各

zì

自

xū

须

xún

寻

gè

各

zì

自

mén

门

。

三春去后诸芳尽，各自须寻各自门。

赏析

【注释】：[评介]这是秦可卿临死前在给凤姐托的梦中留下的最后赠言。它预示着贾府盛极而衰，树倒猢狲散的结局。秦可卿为这个即将崩溃的大家族策划后事，安排退路。她告诫凤姐：“要知道，也不过是瞬息的繁华，一时的欢乐，万不可忘了那‘盛筵必散’的俗语。此时若不早为后虑，临期只恐后悔无益了。”实际上这只不过是秦可卿的一种愿望和幻想，封建社会的衰落是历史发展的必然规律，那是断然不能，也是无法“疗继”的。诗词名句网>>

作者介绍

曹雪芹，名沾，字梦阮，号雪芹，又号芹溪、芹圃。清代著名文学家，小说家。先祖为中原汉人，满洲正白旗包衣出身。素性放达，曾身杂优伶而被钥空房。爱好研究广泛：金石、诗书、绘画、园林、中医、织补、工艺、饮食等。他出身于一个“百年望族”的大官僚地主家庭，因家庭的衰败饱尝人世辛酸，后以坚韧不拔之毅力，历经多年艰辛创作出极具思想性、艺术性的伟大作品《红楼梦》。百科详情>>

热门推荐

© Baidu 使用百度前必读百度首页站内搜索问题反馈商务合作关注微博