購買 R-8204 | R-8204數據表 | Heisener.com
聯繫我們
SalesDept@heisener.com +86-755-83210559 ext. 809

R-8204

R-8204

R-8204

僅供參考

零件編號 R-8204
製造商 TE Connectivity Measurement Specialties
描述 SENSOR PRESSURE
數據表
封裝 -
ECAD
庫存 4,842 piece(s)
單價 Request a Quote
交貨期 待確認
預計送達時間 十二月 27 - 一月 1 (選擇速遞服務)
請求報價
支付方式
送貨服務
  • 我們提供的 R-8204 具有全球市場競爭力的價格,如有需要請發送詢價單給我們。謝謝!
  • 添加 R-8204 及其數量至BOM以便提交您的報價請求。 Heisener.com 無需註冊便可以提交 R-8204 的報價請求。

R-8204參數

製造商TE Connectivity Measurement Specialties
類別感測器、傳感器 - 溫度感測器 - 電阻溫度偵測器 (RTD)
封裝-
ECAD
系列-
抵抗性100 Ohms
公差±0.5%
當前-
安裝類型-
包/箱-
熱敏電阻類型RTD
電壓-
溫度-50°C ~ 180°C
準確性-

R-8204 Packaging

Customized Labels
Sealing
Packing
Insepction

R-8204 FAQ

  • 1. How to order R-8204 on Heisener?
    Currently, Heisener only provide peer-to-peer order processing. While you submit the RFQ, our professional agent will contact you with the competitive prices in the global market, and our agent will prompt you to finish the order if you accept our offers.
  • 2. How does Heisener guarantee that R-8204 is from the original manufacturer or authorized agents?
    We have a professional and experienced quality control team to strictly verify and test the R-8204. All suppliers must pass our qualification reviews before they can publish their products including R-8204 on Heisener; we pay more attention to the channels and quality of R-8204 products than any other customer. We strictly implement supplier audits, so you can purchase with confidence.
  • 3. Are the R-8204 price and inventory displayed accurate?
    The price and inventory of R-8204 fluctuates frequently and cannot be updated in time, it will be updated periodically within 24 hours. And, our quotation usually expires after 5 days.
  • 4. What forms of payment are accepted?
    Wire Transfer, PayPal, Alipay, Wechat, Credit Card, Western Union, MoneyGram, and Escrow are all acceptable.
    Warm Tips: Some orders in certain payment forms may require handling fee.
  • 5. How is the shipping arranged?
    Customers can choose industry-leading freight companies, including DHL, UPS, FedEx, TNT, and Registered Mail. Shipping insurance is also available.
    Once your order has been processed for shipment, our salesperson will send you an email advising you of the shipping status and tracking number.
    Warm Tips: It may take up to 24 hours for the carriers to display tracking information. Usually, express delivery takes 3-5 days, and registered mail takes 25-60 days.
  • 6. What is the process for return or replacement of R-8204?
    All goods will implement Pre-Shipment Inspection (PSI), selected at random from all batches of your order to do a systematic inspection before arranging the shipment. If there is something wrong with the R-8204 we delivered, we will accept the replacement or return of the R-8204 only when all of the below conditions are fulfilled:
    (1)Such as a deficiency in quantity, delivery of wrong items, and apparent external defects (breakage and rust, etc.), and we acknowledge such problems.
    (2)We are informed of the defect described above within 90 days after the delivery of R-8204.
    (3)The PartNo is unused and only in the original unpacked packaging.
    Two processes to return the products:
    (1)Inform us within 90 days
    (2)Obtain Requesting Return Authorizations
  • 7.How to contact us to get technical supports, such as R-8204 pin diagram, R-8204 datasheet?
    If you need any after-sales service, please do not hesitate to contact us.

R-8204相關產品

2220Y5000180KCR 2220Y5000180KCR Knowles Syfer, CAP CER 2220, -, - 查看
MAL212854109E3 MAL212854109E3 Vishay BC Components, CAP ALUM 10UF 20% 10V RADIAL, Radial, - 查看
ISL6520AIR-T ISL6520AIR-T Intersil, IC REG CTRLR BUCK 16QFN, 16-VQFN Exposed Pad, - 查看
PT8A3300BWE PT8A3300BWE Diodes Incorporated, IC HEATING CONTROLLER 8SOIC, -, - 查看
hotLM335AMX/NOPB LM335AMX/NOPB Texas Instruments, SENSOR TEMP ANLG VOLT 8-SOIC, 8-SOIC (0.154", 3.90mm Width), - 查看
hotMW7IC930NR1 MW7IC930NR1 NXP, IC PWR AMP RF 900MHZ TO-270-16, TO-270-16 Variant, Flat Leads, - 查看
RNCF0603DKE91K0 RNCF0603DKE91K0 Stackpole Electronics Inc., RES SMD 91K OHM 0.5% 1/10W 0603, 0603 (1608 Metric), - 查看
ERJ-1TYF102U ERJ-1TYF102U Panasonic Electronic Components, RES SMD 1K OHM 1% 1W 2512, 2512 (6432 Metric), - 查看
850-10-014-30-135101 850-10-014-30-135101 Preci-Dip, CONN HDR 14POS 1.27MM SMD, -, - 查看
DW-10-14-L-S-367 DW-10-14-L-S-367 Samtec Inc., .025" BOARD SPACERS, -, - 查看
1106436-7 1106436-7 TE Connectivity AMP Connectors, CONN HOOD SIDE ENTRY SZ4 M25, -, - 查看
TC7MPB9307FK(EL) TC7MPB9307FK(EL) Toshiba Semiconductor and Storage, X34 DUAL-SUPPLY LEVEL SHIFT BUS, 20-VFSOP (0.118", 3.00mm Width), - 查看

R-8204 保證

Service Guarantee

服務保證

我們保證100%的客戶滿意度。

我們經驗豐富的銷售團隊和技術支持團隊支持我們的服務以滿足所有客戶。

Quality Guarantee

質量保證

我們提供90天保修。

如果您收到的物品質量不合格,我們將負責您的退款或更換,但物品必須以原始狀態退回。

全球供應鏈-可靠的授權分銷商資源

零件編號 製造商 描述 庫存

R-8204

D# V99:2348_17023865

TE Connectivity

Resistance Temperature Detector Thermistor

0

CC0603KRX7R7BB154

D# V72:2272_07128631

YAGEO Corporation

Cap Ceramic 0.15uF 16V X7R 10% Pad SMD 0603 125°C T/R

RoHS: Compliant
0
零件編號 製造商 描述 庫存

CC0603KRX7R7BB154

D# CC0603KRX7R7BB154

YAGEO Corporation

Cap Ceramic 0.15uF 16V X7R 10% SMD 0603 125°C Paper T/R - Tape and Reel (Alt: CC0603KRX7R7BB154)

0

SRF0504-302Y

D# 05R8204

Bourns Inc

Electromechanical Filter 1000Ohm 5uH 0.5A - Bulk (Alt: 05R8204)

0

CRCW04025R10FKED

D# 83R8204

Vishay Intertechnologies

Res Thick Film 0402 5.1 Ohm 1% 1/16W ±100ppm/°C Molded SMD SMD Paper T/R - Tape and Reel (Alt: 83R8204)

RoHS: Compliant
0

R-8204

D# 03AC1724

TE Connectivity

Temp Sensor Analog Serial (3-Wire) - Bulk (Alt: 03AC1724)

RoHS: Compliant
0

E2A-M30LS15-WP-B3 2M

D# E2AM30LS15WPB32M

OMRON Corporation

M30 LSD NPB 15MM PNP NO+NC 2M - Bulk (Alt: E2AM30LS15WPB32M)

0

HXR8204-DNG

D# HXR8204-DNG

Integrated Device Technology Inc

28G - 4 CHANNEL TIA+PA RECEIVER - Gel-pak, waffle pack, wafer, diced wafer on film (Alt: HXR8204-DNG)

0
零件編號 製造商 描述 庫存

CRCW04025R10FKED

D# CRCW04025R10FKED

Vishay Intertechnologies

Res Thick Film 0402 5.1 Ohm 1% 1/16W ±100ppm/°C Molded SMD SMD Paper T/R (Alt: CRCW04025R10FKED)

RoHS: Compliant
0
零件編號 製造商 描述 庫存

R-8204

D# R-8204

TE Connectivity

Temp Sensor Analog Serial (3-Wire) (Alt: R-8204)

RoHS: Compliant
0

CC0603KRX7R7BB154

D# CC0603KRX7R7BB154

YAGEO Corporation

Cap Ceramic 0.15uF 16V X7R 10% SMD 0603 125°C Paper T/R - Tape and Reel (Alt: CC0603KRX7R7BB154)

0

HXR8204-DNT

D# HXR8204-DNT

Renesas Electronics Corporation

RX Optical Fiber 28Gbps DIE (Alt: HXR8204-DNT)

0
零件編號 製造商 描述 庫存

MBR820401.T3

ON Semiconductor

500

CRCW04025R10FKED

Vishay Intertechnologies

28561

CC0603KRX7R7BB154

YAGEO Corporation

20000
零件編號 製造商 描述 庫存

2455R82040033

Honeywell Sensing and Control

COMMERCIAL THERMAL

0

2455R 82040033

Honeywell Sensing and Control

COMMERCIAL THERMAL

0

CRCW04025R10FKED

Vishay Intertechnologies

CRCW Series 0402 0.063 W 5.1 Ohm ?1 % ?100 ppm/K SMT Thick Film Chip Resistor

20000

CC0603KRX7R7BB154

YAGEO Corporation

Multilayer chip capacitors

20000

E2A-M30LS15-WP-B3 2M

OMRON Americas

M30 LSD NPB 15MM PNP NO+NC 2M

0
零件編號 製造商 描述 庫存

CC0603KRX7R7BB154

YAGEO Corporation

150nF ±, 10% 16V X7R 0603 Multilayer Ceramic Capacitors MLCC - SMD/SMT RoHS

22700

FR8204S6CTR

Fitipower Integrated Technology Inc

18V 2A SOT-23-6 DC-DC Converters RoHS

4345
零件編號 製造商 描述 庫存

CRCW04025R10FKED

D# 541-5.10LLTR-ND

Vishay Dale

RES SMD 5.1 OHM 1% 1/16W 0402

0

2455R82040033

D# 2455R82040033-ND

Honeywell Sensing and Control

THERMOSTAT CYLINDER W/ FLANGE QC

0

CC0603KRX7R7BB154

D# 311-1799-1-ND

YAGEO Corporation

CAP CER 0.15UF 16V X7R 0603

22986

HXR8204-DNT

D# 800-HXR8204-DNT-ND

Renesas Electronics Corporation

DIE SALE (PRICE IN GOOD DIE)-WAF

0

E2A-M30LS15-WP-B3 2M

D# E2A-M30LS15-WP-B32M-ND

OMRON Industrial Automation

SENSOR PROX INDUCTIVE 15MM CYL

0

R-8204

D# 223-1635-ND

TE Connectivity

SENSOR RTD 100OHM 0.5%

96
零件編號 製造商 描述 庫存

FR8204S6CTR

Fitipower Integrated Technology Inc

In stock shipping within 2days

24450
零件編號 製造商 描述 庫存

M8744120 BK001

D# 3251003

Alpha Wire

SHLD MULTIPAIR, 12 PAIR, 2.08MM2, 305M

RoHS: Compliant
Min Qty: 1
Container: Reel
0

2CCS573103R8204

D# 3379122

ABB Low Voltage Products and Systems

S403M-C20NP TP&PN MCB C20A 10KA

RoHS: Not Compliant
Min Qty: 1
Container: Each
0

R-8204

D# 3270321

TE Connectivity

RTD,STRR,P100,385,.5%,.030T,H / BOX

RoHS: Not Compliant
Min Qty: 1
Container: Each
3

2CCS571103R8204

D# 3379120

ABB Low Voltage Products and Systems

S401M-C20NP SP&PN MCB C20 10KA

RoHS: Not Compliant
Min Qty: 1
Container: Each
0

CRCW04025R10FKED

D# 2614298

Vishay Intertechnologies

RES, 5R1, 1%, 0.063W, 0402, THICK FILM

RoHS: Compliant
Min Qty: 10000
Container: Reel
0
零件編號 製造商 描述 庫存

CC0603KRX7R7BB154

YAGEO Corporation

0603 0.15 uF 16 V ±10 % Tolerance X7R SMT Multilayer Ceramic Capacitor

RoHS: Compliant
pbFree: Yes
104000

CRCW04025R10FKED

Vishay Intertechnologies

CRCW Series 0402 0.063 W 5.1 Ohm ±1 % ±100 ppm/K SMT Thick Film Chip Resistor

RoHS: Compliant
pbFree: Yes
0

R-8204

TE Connectivity

Pressure Sensor

RoHS: Compliant
pbFree: Yes
0
零件編號 製造商 描述 庫存

CRCW04025R10FKED

Vishay Intertechnologies

OEM/CM QUOTES ONLY | NO BROKERS

19815
零件編號 製造商 描述 庫存

R8204

TE Connectivity

OEM/CM ONLY

37
零件編號 製造商 描述 庫存

R-8204

D# TSSR-8204

TE Connectivity

RTD,STRR,P100,385,.5%,.030T,H TEMPERATURE

0
零件編號 製造商 描述 庫存

FR8204S6CTR

D# C172766

Fitipower Integrated Technology Inc

1835

CC0603KRX7R7BB154

D# C107065

YAGEO Corporation

22700
零件編號 製造商 描述 庫存

CC0603KRX7R7BB154

YAGEO Corporation

0603 0.15UF 10% 16V X7R SURFACE MOUNT MLCC ..........ALT: SPECIALIST IN OFFERING DIRECT EQUIVALENT PARTS FOR MOST MAJOR BRANDS TO REDUCE COSTS AND DELIVERY TIMES.

0
零件編號 製造商 描述 庫存

FR8204S6CTR

Fitipower Integrated Technology Inc

OEM/CM Immediate delivery

25000
零件編號 製造商 描述 庫存

R-8204

D# 824-R-8204

TE Connectivity

Industrial Temperature Sensors RTD,STRR,P100,385,.5%,.030T,H

RoHS: Compliant
15

CC0603KRX7R7BB154

D# 603-CC603KRX7R7BB154

YAGEO Corporation

Multilayer Ceramic Capacitors MLCC - SMD/SMT 150nF 16V X7R 10%

RoHS: Compliant
8326
零件編號 製造商 描述 庫存

CC0603KRX7R7BB154

D# XSFP00000197254

YAGEO Corporation

0603 0.15 uF 16 V 10 % Tolerance X7R SMT Multilayer Ceramic Capacitor

84000
零件編號 製造商 描述 庫存

TSW-132-06-F-T-LL

D# 02R8204

Samtec Inc

HEADER, 2.54MM, THOUGH HOLE VERTICAL, 96 POSITION, Connector Systems:Board-to-Board, Pitch Spacing:2.54mm, No. of Rows:3Rows, No. of Contacts:96Contacts, Contact Termination Type:Through Hole, Product Range:TSW Series, Gender:Header RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 1
Container: Bulk
0

NC1V-1111F-10AM

D# 69R8204

IDEC Corporation

CIRCUIT BREAKER, HYD-MAG, 1P, 250V, 10A, Product Range:NC1V Series, Current Rating:10A, No. of Poles:1 Pole, Input Voltage VAC:250V, Interrupting Capacity:2.5kA, Trip Time:600s, Dielectric Strength:2kV, Voltage Rating VDC:65V RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 1
Container: Bulk
0

15-38-9162

D# 57R8204

Molex

SL FFC/FPC Opt D Male Tin 16Ckt

RoHS: Not Compliant
Min Qty: 780
Container: Bulk
0

RN73C2A37R4BTG

D# 20R8204

TE Connectivity

RES, THIN FILM, 37R4, 0.1%, 0.1W, 0805, Resistance:37.4ohm, Resistance Tolerance:± 0.1%, Power Rating:100mW, Resistor Case Style:0805 [2012 Metric], Resistor Technology:Thin Film, Resistor Type:Precision, Product Range:RN73 Series RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 250
Container: Cut Tape
0

39543-7018

D# 59R8204

Molex

5.0MM EUROBLOCK PC VERT BLK 11A 18CKT

RoHS: Not Compliant
Min Qty: 252
Container: Bulk
0

TSW-207-18-T-S

D# 03R8204

Samtec Inc

HEADER, 5.08MM, THROUGH HOLE VERTICAL, 7 POSITION, Connector Systems:Board-to-Board, Pitch Spacing:5.08mm, No. of Rows:1Rows, No. of Contacts:7Contacts, Contact Termination Type:Through Hole, Product Range:TSW Series, Gender:Header RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 1
Container: Bulk
0

CRCW04025R10FKED

D# 83R8204

Vishay Intertechnologies

RES, THICK FILM, 5R1, 1%, 0.063W, 0402, REEL, Resistance:5.1ohm, Resistance Tolerance:± 1%, Power Rating:62.5mW, Resistor Case Style:0402 [1005 Metric], Resistor Technology:Thick Film, Resistor Type:General Purpose, No. of Pins:2 RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 20000
Container: TAPE & REEL - FULL
0

R-8204

D# 03AC1724

TE Connectivity

RTD,STRR,P100,385,.5%,.030T,H / BOX

RoHS: Not Compliant
Min Qty: 1
Container: Bulk
3

20021122-00024T4LF

D# 82R8204

Amphenol Fiber Systems International

20021122-00024T4LF-HD RA SMT / Tube RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 1260
Container: Bulk
0

E2A-M30LS15-WP-B3 2M

D# 08R8204

OMRON Industrial Automation

M30 LSD NPB 15mm PNP NO+NC 2M

RoHS: Not Compliant
Min Qty: 1
Container: Bulk
0

6010-0147-P1

D# 51R8204

PACE Worldwide

HANDPIECE, TD-100, INTELLIHEAT, Supply Voltage V AC:230V, Output Power:-, Heat Temperature Max:-, Product Range:-, Plug Type:-, SVHC:No SVHC (15-Jan-2018) RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 1
Container: Bulk
0

TAJA225K010SNJ

D# 73R8204

AVX Corporation

TANTALUM CAPACITOR, 2.2UF, 10V, 1206 10%, Capacitance:2.2µF, Voltage Rating:10V, Tantalum Capacitor Case:1206 [3216 Metric], Product Range:TAJ Series, Capacitance Tolerance:± 10%, Operating Temperature Min:-55°C, ESR:7ohm RoHS Compliant: Yes

RoHS: Compliant
Min Qty: 8000
Container: Cut Tape
0

75235-2215

D# 56R8204

Molex

GBX BACKPLANE 4 Pair 25 Col Left End Ass

RoHS: Not Compliant
Min Qty: 40
Container: Bulk
0

M8744120 BK001

D# 89R8204

Alpha Wire

AE TRAY CABLE BK 1 1000 FT EACH

RoHS: Not Compliant
Min Qty: 5
Container: Spool
0
零件編號 製造商 描述 庫存

2455R82040033

D# NS-2455R82040033

Honeywell Sensing and Control

OEM/CM ONLY

1153

CRCW04025R10FKED

D# NS-CRCW04025R10FKED

Vishay Dale

OEM/CM ONLY

40066

E2A-M30LS15-WP-B3 2M

D# NS-E2A-M30LS15-WP-B3 2M

OMRON Industrial Automation

OEM/CM ONLY

7378
零件編號 製造商 描述 庫存

CRCW04025R10FKED

Vishay Intertechnologies

RESISTOR, METAL GLAZE/THICK FILM, 0.063 W, 1 %, 100 PPM, 5.1 OHM, SURFACE MOUNT, 0402, LEAD FREE

8263
零件編號 製造商 描述 庫存

R-8204

D# 000000000005396614

TE Connectivity

Industrial Temperature Sensors RTD,STRR,P100,385,.5%,.030T,H

0

2455R 82040033

D# 000000000002156825

Honeywell Sensing and Control

Thermostats COMMERCIAL THERMAL

0
零件編號 製造商 描述 庫存

IBM FAN FRU:42R7657 / FOR 8204E8A

OEM/CM ONLY

3011

FR8204S6CTR

Fitipower Integrated Technology Inc

OEM/CM ONLY

27011

FR8204S6GTR

Fitipower Integrated Technology Inc

OEM/CM ONLY

30011

MBR820401.T3

OEM/CM ONLY

516

HC62R82.048MHZ

ILSI America LLC

OEM/CM ONLY

1414

S15R82.048000

CONNOR

OEM/CM ONLY

49

R8204

TE Connectivity

OEM/CM ONLY

166

CRCW04025R10FKED

Vishay Intertechnologies

OEM/CM ONLY

102222

TR8204

OEM/CM ONLY

145

CC0603KRX7R7BB154

YAGEO Corporation

OEM/CM ONLY

69631
零件編號 製造商 描述 庫存

FR8204S6CTR

Fitipower Integrated Technology Inc

IN stock Immediate delivery

24985
零件編號 製造商 描述 庫存

R-8204

TE Connectivity

Industrial Temperature Sensors RTD,STRR,P100,385,.5%,.030T,H

0

SRF0504-302Y

Bourns Inc

Common Mode Chokes / Filters 6 uH 500mA 30-150MHz

pbFree: Pb-Free
0

CRCW04025R10FKED

Vishay Intertechnologies

Thick Film Resistors - SMD 1/16watt 5.1ohms 1%

pbFree: Pb-Free
0

CC0603KRX7R7BB154

YAGEO Corporation

Multilayer Ceramic Capacitors MLCC - SMD/SMT 150nF 16V X7R 10%

pbFree: Pb-Free
0
零件編號 製造商 描述 庫存

FR8204AS6CTR

Fitipower Integrated Technology Inc

shipping today

9999

FR8204S6CTR

Fitipower Integrated Technology Inc

shipping today

59999
零件編號 製造商 描述 庫存

CRG0805-R-8204FT

VENKEL LTD

RoHS 6/6 Green CR, 0805, 1/8W, 8.2M, 1%

RoHS: Compliant
0
零件編號 製造商 描述 庫存

R-8204

D# 25622230

TE Connectivity

Resistance Temperature Detector Thermistor

0

CC0603KRX7R7BB154

D# 50954139

YAGEO Corporation

Cap Ceramic 0.15uF 16V X7R 10% Pad SMD 0603 125°C T/R

RoHS: Compliant
0
零件編號 製造商 描述 庫存

FR8204S6CTR

Fitipower Integrated Technology Inc

70580
零件編號 製造商 描述 庫存

R-8204

D# 3270321

TE Connectivity

RTD,STRR,P100,385,.5%,.030T,H / BOX

RoHS: Not Compliant
Min Qty: 1
Container: Each
13

CRCW04025R10FKED

D# 2616739

Vishay Intertechnologies

RES, 5R1, 1%, 0.063W, 0402, THICK FILM

RoHS: Compliant
Min Qty: 10
Container: Cut Tape
440

Quick Inquiry

R-8204

質量認證

黑森爾對質量的承諾,塑造了我們的採購、測試、運輸流程以及它們之間的每一步。這個基準是我們所銷售的每一個元器件的基礎。

ISO9001:2015, ICAS, IAF, UKAS

查看證書

聯繫我們

您有關於 R-8204 的問題嗎?

R-8204 QRCode

掃描以查看此頁面

推薦產品

LM137K

IC REG LINEAR NEG ADJ 1.5A TO3

ADM1021ARQ

IC SENSOR TEMP DUAL3/5.5V 16QSOP

LTC1844ES5-2.5#TRMPBF

IC REG LIN 2.5V 150MA TSOT23-5

S202T01

RELAY SSR 240VAC 2A TRIAC 4-SIP

B3S-1002P

SWITCH TACTILE SPST-NO 0.05A 24V

WSL0805R0500FEA

RES SMD 0.05 OHM 1% 1/8W 0805

PC28F256P30TFE

IC FLASH 256MBIT 100NS 64EASYBGA

PIC16F77-I/P

IC MCU 8BIT 14KB FLASH 40DIP

CK45-R3DD102KAVRA

CAP CER DISC RADIAL

MAX6370KA+T

IC TIMER WATCHDOG SOT23-8

更多 »

R-8204 Tags

  • R-8204
  • R-8204 PDF
  • R-8204 數據表
  • R-8204 規格
  • R-8204 圖片
  • TE Connectivity Measurement Specialties
  • TE Connectivity Measurement Specialties R-8204
  • 買R-8204
  • R-8204 價格
  • R-8204 經銷商
  • R-8204 供應商
  • R-8204 批發

R-8204可用於