²é¿´: 4114  |  »Ø¸´: 51
¡¾½±Àø¡¿ ±¾Ìû±»ÆÀ¼Û46´Î£¬×÷ÕßdcbaabÔö¼Ó½ð±Ò 36 ¸ö
µ±Ç°Ö»ÏÔʾÂú×ãÖ¸¶¨Ìõ¼þµÄ»ØÌû£¬µã»÷ÕâÀï²é¿´±¾»°ÌâµÄËùÓлØÌû

dcbaab

Ìú¸Ëľ³æ (СÓÐÃûÆø)


[×ÊÔ´] ²âÁ¿ÒDZíÓë²âÁ¿¼¼Êõ_Ô­ÊéµÚ¶þ°æ_£¨ÃÀ£©ROBERT B.NORTHROP_»úе¹¤Òµ³ö°æÉç_2009.06

ÄÚÈݼò½é
    ¡¶²âÁ¿ÒDZíÓë²âÁ¿¼¼Êõ£¨Ô­ÊéµÚ2°æ£©¡·ÄÚÈÝÉæ¼°²âÁ¿ÏµÍ³µÄ»ù´¡ÖªÊ¶¡¢»ù±¾Ô­Àí¡¢Éè¼Æ·½·¨ÓëÓ¦ÓÃʵÀý£¬Ñ¡²Äʱ¼ä¿ç¶È´ó¡¢¸²¸ÇÃæ¹ã£¬³ä·Ö·´Ó³ÁËÏÖ´ú²âÁ¿ÀíÂÛÒÔ¼°¼¯³Éµç·¡¢¹â×Óʽ´«¸ÐÆ÷¡¢Î¢ÐÍ´«¸ÐÆ÷¡¢Ðźŵ÷Õû¡¢ÔëÉù¡¢Êý×Ö½Ó¿ÚºÍÊý×ÖÐźŴ¦Àí£¨DsP£©µÈ×îм¼Êõ³É¹ûÔÚ²âÁ¿ÒDZíÖеÄÓ¦ÓᣴËÍ⣬¡¶²âÁ¿ÒDZíÓë²âÁ¿¼¼Êõ£¨Ô­ÊéµÚ2°æ£©¡·Éæ¼°µØÇòÎïÀíѧÒÇ±í¡¢»¯Ñ§ÒDZíºÍ¹âѧÒDZíµÈÖî¶àÁìÓò£¬Äܹ»·´Ó³³öÏÖ´ú¼¼Êõ¶Ô²âÁ¿ÏµÍ³µÄÓ°Ïì¡£¡¶²âÁ¿ÒDZíÓë²âÁ¿¼¼Êõ£¨Ô­ÊéµÚ2°æ£©¡·¼È¿É×÷Ϊ¿ÆÑÐÔºËù¡¢¸ßµÈ¹¤¿ÆÔºÐ£µÈÏà¹Ø×¨ÒµµÄ½Ì²Ä»ò½Ìѧ²Î¿¼Ê飬Ҳ¿É×÷Ϊ²âÁ¿ÒDZíÉè¼Æ¡¢ÖÆÔì¡¢¼ì²âÓëάÐÞÈËÔ±µÈµÄ¼¼ÊõÖ¸ÄÏ»ò¹¤¾ßÊé¡£
Ŀ¼
ÒëÕßÐò
ǰÑÔ
µÚ1Õ ²âÁ¿ÏµÍ³
1.1 ÒýÑÔ
1.2 ²âÁ¿ÏµÍ³µÄ½á¹¹
1.2.1 ´«¸ÐÆ÷µÄ¶¯Ì¬ÌØÐÔ
1.2.2 Ðźŵ÷ÕûС½á
1.3 ²âÁ¿Îó²î
1.3.1 ¹ýʧÎó²î
1.3.2 ϵͳÎó²î
1.4 ²âÁ¿±ê×¼
1.4.1 µçÆø±ê×¼
1.4.1.1 µçλ²î
1.4.1.2 µç×è
1.4.1.3 µçÁ÷ºÍµçºÉ
1.4.1.4 µçÈÝ
1.4.1.5 µç¸Ð
1.4.2 ʱ¼äºÍƵÂÊ
1.4.3 ÎïÀí±ê×¼
1.4.3.1 ÖÊÁ¿
1.4.3.2 ³¤¶È
1.4.3.3 ζÈ
1.4.3.4 ¹ú¼Êµ¥Î»ÖƵĻù±¾µ¥Î»
1.5 ±¾ÕÂС½á
ϰÌâ

µÚ2Õ ģÄâÐźŵ÷Õû
2.1 ÒýÑÔ
2.2 ²î¶¯·Å´óÆ÷
2.2.1 ²î¶¯·Å´óÆ÷ÌØÐÔ·ÖÎö
2.2.2 ¹²Ä£ÒÖÖÆ±È
2.2.3 ¹²Ä£ÒÖÖÆ±È¡¢ADºÍAcµÄ²âÁ¿
2.2.4 ÄÚ×費ƽºâ¶Ô¹²Ä£ÒÖÖÆ±ÈµÄÓ°Ïì
2.3 ÔËËã·Å´óÆ÷
2.3.1 ÔËËã·Å´óÆ÷µÄ·ÖÀà
2.3.2 ÀûÓÃÔËËã·Å´óÆ÷Éè¼Æ»ù±¾µÄ¿í´ø·Å´óÆ÷
2.3.2.1 ͬÏà·Å´óÆ÷
2.3.2.2 ·´Ïà·Å´óÆ÷¼°¼Ó·¨Æ÷
2.3.3 µçÁ÷·´À¡ÐÍÔËËã·Å´óÆ÷
2.4 ÀûÓÃÆÕͨÔËËã·Å´óÆ÷¹¹³ÉÄ£ÄâÓÐÔ´Â˲¨Æ÷
2.4.1 ÒýÑÔ
2.4.2 Ä£ÄâÓÐÔ´Â˲¨Æ÷½á¹¹
2.4.2.1 ÊÜ¿ØÔ´ÓÐÔ´Â˲¨Æ÷
2.4.2.2 ËÄ´ÎÓÐÔ´Â˲¨Æ÷
2.4.2.3 ͨÓÃ×迹±ä»»Æ÷ÓÐÔ´Â˲¨Æ÷
2.4.2.4 ¸ß½×ÓÐÔ´Â˲¨Æ÷
2.4.3 ÔËËã·Å´óÆ÷»ý·ÖÆ÷ºÍ΢·ÖÆ÷
2.4.4 С½á
2.5 ²âÁ¿·Å´óÆ÷
2.5.1 ²ÉÓÃÔËËã·Å´óÆ÷¹¹³ÉµÄ²âÁ¿·Å´óÆ÷
2.5.2 ¸ôÀë·Å´óÆ÷
2.5.3 ×Ô¶¯µ÷ÁãÐÍ·Å´óÆ÷
2.5.4 ¾ø¶Ô¸ôÀë·½°¸
2.5.5 С½á
2.6 ÀûÓÃÔËËã·Å´óÆ÷ºÍÌØÊ⺯ÊýÄ£ÐͽøÐзÇÏßÐÔÄ£ÄâÐźŴ¦Àí
2.6.1 ÒýÑÔ
2.6.2 ¾«Ãܾø¶ÔÖµµç·
2.6.3 ¶à¹¦ÄÜת»»Æ÷
2.6.4 ÕæÓÐЧֱֵÁ÷ת»»Æ÷
2.6.5 ƽ·½¸ùµç·ºÍ³ý·¨Æ÷µç·
2.6.6 ·åÖµ¼ì²âÆ÷ºÍ¸ú×ÙÒ»±£³Öµç·
2.6.7 ¶ÔÊý±ÈºÍÈý½Çº¯Êý¼¯³Éµç·
2.6.8 С½á
2.7 µçºÉ·Å´óÆ÷
2.7.1 ÓÃ×÷ѹµç´«¸ÐÆ÷µÄµçºÉ·Å´óÆ÷
2.7.2 ÓÃ×÷»ý·ÖµçÁ¿¼ÆµÄµçºÉ·Å´óÆ÷
2.7.3 С½á
2.8 ÏàÃô¼ì²¨Æ÷
2.8.1 Ë«±ß´øÒÖÖÆÔØ²¨µ÷ÖÆ
2.8.2 ÀûÓÃÄ£Äâ³Ë·¨Æ÷½âµ÷DsBscMÐźÅ
2.8.3 ÆäËûÏàÃô¼ì²¨Æ÷Éè¼Æ
2.8.4 Ëø¶¨·Å´óÆ÷
2.8.4.1 ÒýÑÔ
2.8.4.2 ÀûÓÃËø¶¨·Å´óÆ÷Ìá¸ßµÄÐÅÔë±È¼ÆËã
2.8.5 С½á
2.9 ±¾ÕÂС½á
ϰÌâ

µÚ3Õ ²âÁ¿ÖеÄÔëÉùºÍÏà¸É¸ÉÈÅ
3.1 ÒýÑÔ
3.2 µç·ÖеÄËæ»úÔëÉù
3.2.1 ¸ÅÂÊÃܶȺ¯Êý
3.2.2 ¹¦ÂÊÃÜ¶ÈÆ×
3.2.3 Ðźŵ÷ÕûϵͳÖеÄÔëÉùÔ´
3.2.3.1 µç×èÆ÷ÔëÉù
3.2.3.2 ÓÐÔ´Æ÷¼þµÄÁ½Ô´ÔëÉùÄ£ÐÍ
3.2.3.3 JFETÖеÄÔëÉù
3.2.3.4 JFETÖеÄÔëÉù
3.3 ¸ß˹ÔëÉùͨ¹ýÏßÐÔÂ˲¨Æ÷µÄ´«²¥
3.4 ·Å´óÆ÷µÄ¿í´øÔëÉùÒòÊýºÍÔëÉùϵÊý
3.5 µãÔëÉùÒòÊýºÍµãÔëÉùϵÊý
¡­¡­
µÚ4Õ ֱÁ÷Áãλ²âÁ¿·¨
µÚ5Õ ½»Á÷Áãλ²âÁ¿·¨
µÚ6Õ ´«¸ÐÆ÷
µÚ7Õ ÎïÀíÁ¿²âÁ¿Öд«¸ÐÆ÷µÄÓ¦ÓÃ
µÚ8Õ »ù±¾µÄµçÆø²âÁ¿
µÚ9Õ ²âÁ¿ÏµÍ³µÄÊý×Ö½Ó¿Ú
µÚ10Õ Êý×ÖÐźŵ÷Õûµ¼ÂÛ
µÚ11Õ ²âÁ¿ÏµÍ³Éè¼ÆÊµÀý
¸½Â¼³£ÓüÆÁ¿µ¥Î»¼°Æä»»Ëã±í
²Î¿¼ÎÄÏ×
ÊÕÆðÈ«²¿
ǰÑÔ
    ÏÖ´ú¼¼ÊõµÄ·¢Õ¹£¬ÌرðÊÇÏÖ´úµç×Ó¼¼ÊõÓëÖÆÔ칤Òյķ¢Õ¹£¬´ßÉú²¢Íƶ¯×ŲâÁ¿ÒDZíÓë²âÁ¿¼¼ÊõµÄ²»¶Ï¸üÐÂÓë¿ìËÙ·¢Õ¹£¬Ê¹ÆäÔÚ»úе¡¢µç×Ó¡¢²â¿Ø¡¢×Ô¶¯»¯µÈÁìÓòÒÔ¼°¹ú·À²¿ÃÅÖлñµÃ´óÁ¿Ó¦Ó㬸ߵȹ¤¿ÆÔºÐ£»úе¡¢²âÁ¿»òÒDZíµÈרҵµÄÔÚУѧÉúÒÔ¼°´ÓʲâÁ¿ÒDZíÓë²âÁ¿¼¼Êõ¿ÆÑС¢Éú²ú¡¢Ó¦Óõȹ¤×÷µÄ¹¤³Ì¼¼ÊõÈËÔ±ÆÈÇÐÐèÒªÒ»±¾Äܹ»ÊÊÓ¦ºÍ·´Ó³²âÁ¿ÒDZíÓë²âÁ¿¼¼Êõ¾ç±äµÄרҵ½Ì¿ÆÊéºÍ¼¼Êõ²Î¿¼×ÊÁÏ¡£¼øÓÚ´Ë£¬»úе¹¤Òµ³ö°æÉ缰ʱÒý½øÁ˱¾ÊéµÄÓ¢ÎÄÔ­°æ£¬¿ÉνÓëʱ¾ã½ø¡£
    ±¾Êé¹²·Ö11Õ£¬µÚ1Õ½éÉܲâÁ¿ÏµÍ³µÄ»ù±¾¸ÅÄµÚ2Õ½éÉÜÄ£ÄâÐźŵ÷Õû£»µÚ3ÕÂÉîÈëÌÖÂÛÔëÉùºÍ´®ÈŸø²âÁ¿½á¹û´øÀ´µÄÓ°Ï죻µÚ4Õº͵Ú5Õ·ֱð½éÉÜÁË´«Í³µÄÖ±Á÷ƽºâ²âÁ¿·¨ºÍ½»Á÷ƽºâ²âÁ¿·¨£»µÚ6ÕÂÖ÷Òª½éÉÜ´«¸ÐÆ÷£»µÚ7Õ¸ø³öÁË´«¸ÐÆ÷ÔÚÎïÀíÁ¿²âÁ¿ÖеÄÓ¦Ó㻵Ú8ÕÂÃèÊöÁË»ù±¾µÄµçÆø²âÁ¿£»µÚ9ÕÂÖ÷Òª¶Ô²âÁ¿ÏµÍ³µÄÊý×Ö½Ó¿Ú½øÐзÖÎö£»µÚ10Õ½éÉÜÊý×ÖÐźŵ÷Õû£»µÚ11Õ¸ø³öÁ˲âÁ¿ÏµÍ³µÄÉè¼ÆÊµÀý¡£±¾ÊéÂß¼­²ã´ÎÇåÎú£¬Í¼ÎIJ¢Ã¯£¬Êýѧ·ÖÎöÍ»³ö¡£±¾Êé¾ßÓÐÒÔÏÂÌØÉ«£º
    ϵͳÐÔ£º±¾Êé²Î¿¼×ÊÁÏÑ¡²ÄµÄʱ¼ä¿ç¶È´Ó20ÊÀ¼Í50Äê´úÒ»Ö±ÑÓÐøÖÁ½ñ£¬¼ÈÏêϸ½éÉÜÁ˲âÁ¿ÏµÍ³µÄ»ù´¡ÖªÊ¶£¬ÓÖ½éÉÜÁ˲âÁ¿ÏµÍ³µÄÓ¦ÓÃÓëÉè¼ÆÊµÀý£¬¸²¸ÇÃæ¼«¹ã£¬³ä·Ö·´Ó³ÁËÏÖ´ú²âÁ¿ÀíÂÛºÍ×îм¼Êõ³É¹ûÔÚ²âÁ¿ÒDZíÖеÄÓ¦Óá£Í¨¹ýÔĶÁ±¾Ê飬¿ÉÒÔ°ïÖú¶ÁÕß¼ÈÁ˽â²âÁ¿ÏµÍ³µÄ·¢Õ¹£¬ÓÖÄܳä·ÖѧϰÏÖ´ú²âÁ¿ÀíÂÛºÍ×îм¼Êõ³É¹û¡£
    ʵÓÃÐÔ£º±¾Êé²ûÊöÁ˳£ÓõIJâÁ¿ÏµÍ³µÄÔ­ÀíºÍÉè¼Æ·½·¨£¬½éÉÜÁ˲âÁ¿ÏµÍ³Ð¼¼Êõ¼°ÆäÉè¼ÆÊµÀý£¬¸ÅÄîÔ­Àí½²½âÓëÓ¦ÓÃʵÀý½éÉÜÏศÏà³É£¬²¢ÅäÓÐϰÌ⣬¼ÈÀûÓÚ½Ìѧ£¬ÓÖ±ãÓÚ×Ôѧ¡£Í¨¹ýÔĶÁ±¾Ê飬¿ÉÒÔ°ïÖú¶ÁÕ߾߱¸²âÁ¿ÏµÍ³·½ÃæµÄ»ù´¡ÖªÊ¶ºÍÓ¦ÓÃÉè¼ÆÄÜÁ¦¡£
»Ø¸´´ËÂ¥

» ±¾Ìû¸½¼þ×ÊÔ´Áбí

» ÊÕ¼±¾ÌûµÄÌÔÌûר¼­ÍƼö

Ä£Äâ¼ÆËã Mechanical Relevant Æû³µ½ÚÄÜÓë»·±£ lgzxÊÕ²Ø
»úе Metal Technology ×ÊÁÏÊÕ¼¯ ÊÔÑé·½·¨²âÁ¿Ïà¹Ø

» ²ÂÄãϲ»¶

» ±¾Ö÷ÌâÏà¹Ø¼ÛÖµÌùÍÆ¼ö£¬¶ÔÄúͬÑùÓаïÖú:

ÒÑÔÄ   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

Ä˸¶

гæ (³õÈëÎÄ̳)


¡ï¡ï¡ï ÈýÐǼ¶,Ö§³Ö¹ÄÀø

Ò»Ö±Ïë¿´¿´£¬¾ÍÊÇûÓÐÕÒµ½¡£Ð»Ð»·ÖÏí

[ ·¢×ÔСľ³æ¿Í»§¶Ë ]
9Â¥2014-06-12 22:58:10
ÒÑÔÄ   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
²é¿´È«²¿ 52 ¸ö»Ø´ð

dcbaab

Ìú¸Ëľ³æ (СÓÐÃûÆø)


²âÁ¿Êǹ¤¿Æ×¨Òµ¶¼Ó¦¸ÃÁ˽âµÄ£¬ÏàÐŶÔÒÔºóµÄ¹¤×÷ѧϰ¶¼»áÓаïÖú
4Â¥2014-05-06 18:57:56
ÒÑÔÄ   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû

tiger308

гæ (³õÈëÎÄ̳)


¡ï¡ï¡ï¡ï¡ï ÎåÐǼ¶,ÓÅÐãÍÆ¼ö

¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡ºÃÊ飡£¡£¡
8Â¥2014-06-12 22:48:05
ÒÑÔÄ   ¹Ø×¢TA ¸øTA·¢ÏûÏ¢ ËÍTAºì»¨ TAµÄ»ØÌû
¼òµ¥»Ø¸´
yihongshi2Â¥
2014-04-30 09:40  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
2014-04-30 22:15  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
2014-05-18 19:45  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
shihj6Â¥
2014-05-19 14:10  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
leiqhd10Â¥
2014-06-27 11:21  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
nieqiue11Â¥
2014-07-02 07:02  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
supervb12Â¥
2014-07-02 07:19  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
liulius13Â¥
2014-07-15 21:43  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
ÓÚʯ1114Â¥
2014-08-01 18:19  
ÎåÐÇºÃÆÀ  ¶¥Ò»Ï£¬¸Ðл·ÖÏí£¡
×î¾ßÈËÆøÈÈÌûÍÆ¼ö [²é¿´È«²¿] ×÷Õß »Ø/¿´ ×îºó·¢±í
[¿¼ÑÐ] 310Çóµ÷¼Á +3 baibai1314 2026-03-16 3/150 2026-03-21 03:56 by JourneyLucky
[¿¼ÑÐ] 303Çóµ÷¼Á +5 î£08 2026-03-17 7/350 2026-03-21 03:11 by JourneyLucky
[¿¼ÑÐ] 278Çóµ÷¼Á +6 ÑÌ»ðÏÈÓÚ´º 2026-03-17 6/300 2026-03-21 01:57 by JourneyLucky
[¿¼ÑÐ] Ò»Ö¾Ô¸»ªÖпƼ¼´óѧ£¬080502£¬354·ÖÇóµ÷¼Á +5 ÊØºòϦÑôCF 2026-03-18 5/250 2026-03-21 01:06 by JourneyLucky
[¿¼ÑÐ] 274Çóµ÷¼Á +10 S.H1 2026-03-18 10/500 2026-03-20 23:51 by JourneyLucky
[¿¼ÑÐ] 287Çóµ÷¼Á +7 ³¿»èÏßÓëÐǺ£ 2026-03-19 8/400 2026-03-20 22:19 by JourneyLucky
[¿¼ÑÐ] Ò»Ö¾Ô¸ËÕÖÝ´óѧ²ÄÁÏÇóµ÷¼Á£¬×Ü·Ö315£¨Ó¢Ò»£© +5 sbdksD 2026-03-19 5/250 2026-03-20 22:10 by luoyongfeng
[¿¼ÑÐ] 329Çóµ÷¼Á +9 ÏëÉÏѧ߹߹ 2026-03-19 9/450 2026-03-20 22:01 by luoyongfeng
[¿¼ÑÐ] Çóµ÷¼Á +3 @taotao 2026-03-20 3/150 2026-03-20 19:35 by JourneyLucky
[¿¼ÑÐ] ²ÄÁÏÓ뻯¹¤×¨Ë¶µ÷¼Á +7 heming3743 2026-03-16 7/350 2026-03-20 19:31 by zhukairuo
[¿¼ÑÐ] 286·ÖÈ˹¤ÖÇÄÜרҵÇëÇóµ÷¼ÁÔ¸Òâ¿ç¿¼£¡ +3 lemonzzn 2026-03-17 4/200 2026-03-20 11:04 by lemonzzn
[¿¼ÑÐ] Ò»Ö¾Ô¸Öйúº£Ñó´óѧ£¬ÉúÎïѧ£¬301·Ö£¬Çóµ÷¼Á +5 1ËïÎò¿Õ 2026-03-17 6/300 2026-03-19 23:46 by zcl123
[¿¼ÑÐ] 085601²ÄÁϹ¤³Ìר˶Çóµ÷¼Á +10 Ľº®mio 2026-03-16 10/500 2026-03-19 15:26 by ¶¡¶¡*
[¿¼ÑÐ] 328Çóµ÷¼Á£¬Ó¢ÓïÁù¼¶551£¬ÓпÆÑо­Àú +4 ÉúÎ﹤³Ìµ÷¼Á 2026-03-16 12/600 2026-03-19 11:10 by ÉúÎ﹤³Ìµ÷¼Á
[¿¼ÑÐ] ²ÄÁÏ£¬·ÄÖ¯£¬ÉúÎ0856¡¢0710£©£¬»¯Ñ§ÕÐÉúÀ² +3 Eember. 2026-03-17 9/450 2026-03-18 10:28 by Eember.
[¿¼ÑÐ] 11408 Ò»Ö¾Ô¸Î÷µç£¬277·ÖÇóµ÷¼Á +3 zhouzhen654 2026-03-16 3/150 2026-03-17 07:03 by laoshidan
[¿¼ÑÐ] 326Çóµ÷¼Á +4 ŵ±´¶û»¯Ñ§½±êéê 2026-03-15 7/350 2026-03-16 17:11 by ŵ±´¶û»¯Ñ§½±êéê
[¿¼ÑÐ] 318Çóµ÷¼Á +3 Yanyali 2026-03-15 3/150 2026-03-16 16:41 by houyaoxu
[¿¼ÑÐ] 304Çóµ÷¼Á +3 ÂüÊâ2266 2026-03-14 3/150 2026-03-16 16:39 by houyaoxu
[¿¼ÑÐ] 080500£¬²ÄÁÏѧ˶302·ÖÇóµ÷¼ÁѧУ +4 ³õʶ¿ÉÀÖ 2026-03-14 5/250 2026-03-14 21:08 by peike
ÐÅÏ¢Ìáʾ
ÇëÌî´¦ÀíÒâ¼û