首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This study was conducted to investigate the effects of increasing levels of extracts of Byrsonima crassifolia, Celtis pallida, Enterolobium cyclocarpum, Fraxinus excelsior, Ficus trigonata, Phoradendrom brevifolium and Prunus domestica on in vitro gas production (GP) and ruminal fermentation of a high concentrate diet. Plant extracts were prepared at 1 g dry matter (DM)/8 mL of solvent mixture (methanol : ethanol : water, 1:1:8) and added at levels of 0, 0.6, 1.2 and 1.8 mL/g DM of a high concentrate diet. In vitro GP was recorded at 2, 4, 6, 8, 10, 12, 24, 48 and 72 h of incubation. Increasing addition of extracts linearly increased (P < 0.001), the GP24, GP48 and GP72 (mL/g DM), and linearly decreased (P < 0.001), the discrete GP lag time. Moreover, increasing extract doses linearly increased (P < 0.001) the asymptotic GP and decreased (P < 0.001) the rate of GP. GP6 was not impacted by treatments and GP12 increased linearly (P = 0.01) with increasing addition of extracts. Rumen pH declined linearly (P < 0.05) with increasing doses of extracts added. As no interactions (P > 0.05) occurred between the extracts and doses, it could be conclude that all extracts positively modified rumen fermentation at doses of 1.2 to 1.8 mL extract/g diet DM.  相似文献   

2.
Gum arabic (GA) has potential rumen modifier functions. This is the first study to investigate the in vitro ruminal fermentation characteristics of GA. Rumen fluid was collected from ruminal fistulated wethers; rolled barley and ryegrass straw were used as substrates for concentrate and forage conditions, respectively. Besides incubating with the substrates alone (control), GA or potato starch (PS) was added at 0.2%, 1.0%, and 2.0% along with substrates. Under the concentrate substrate condition, GA treatments showed higher total gas production in 24-h incubation, but lower methane production in 24- and 48-h incubation compared with PS treatments (p < 0.05). The 1.0% and 2.0% GA and 0.2% and 1.0% PS treatments showed higher dry matter and neutral detergent fiber digestibility and lower NH3-N, and higher short chain fatty acid concentrations compared with the control at 24-h incubation (p < 0.05). The GA treatments also showed a lower acetate/propionate ratio than PS treatments at 48-h incubation (p < 0.01). Under the forage substrate condition, the treatment effects were not significant, except for a higher proportion of propionate with GA than with PS at 24 and 48 h of incubations. We thus concluded that GA supplement may exert potential rumen modifier effects particularly under concentrate feeding condition.  相似文献   

3.
在精粗比为50∶50的滩羊日粮中,添加不同比例的裂壶藻粉(0,1%,2%,3%)进行了体外批次发酵培养,测定不同时间点的产气量、pH、中性洗涤纤维(NDF)、氨态氮浓度(NH3-N)、微生物蛋白(MCP)和挥发性脂肪酸(VFA)含量,计算不同组合的单项组合效应指数(SFAEI)和多项组合效应指数(MFAEI),探讨裂壶藻粉藻在瘤胃中最佳的添加比例。结果表明:添加比例为3%裂壶藻粉组产气量、pH及NH3-N浓度最高(P<0.05),2%裂壶藻粉组NDF消化率、VFA浓度最高(P<0.05),1%裂壶藻粉组MCP浓度最高(P<0.05)。研究结果显示,在精粗比为50∶50的日粮条件下,裂壶藻粉在滩羊日粮中的适宜添加比例为2%。  相似文献   

4.
The effects of doses CTL (0 mg), 30, 300 and 3000 mg/L of extracts from Stryphnodendron adstringens (Mart.) Coville (SA), Lafoensia pacari A. St.-Hil (LP), Copaifera spp. (CO) and Pterodon emarginatus Vogel (PE) on ruminal fermentation were investigated in eight experiments conducted in randomized complete block designs. The in vitro system contained four fermentation vessels. Each treatment was allocated in one vessel in each run. Incubation was run four and five times with diets 50:50 and 10:90 (roughage to concentrate ratio) respectively. Incubation vessel was the experimental unit, and each incubation run was a block. All plant extracts negatively affected DM degradation at 3000 mg/L. In diet 50:50, SA-3000 increased the molar proportion of propionate (p < 0.05), yet it decreased the concentration of fermentation products (p < 0.05); LP-300 reduced ruminal ammonia nitrogen (NH3-N; 98 vs. 120 mg/dl for LP-300 and average of CTL and LP-30, respectively) and isobutyrate (p < 0.05); CO-300 reduced (p < 0.05) NH3-N (98 vs. 123 mg/dl for CO-300 and average of CTL and CO-30, respectively); and P. emarginatus had no positive effects on rumen fermentation (p > 0.05). In diet 10:90, SA-300 reduced (p < 0.001) NH3-N and total volatile fatty acids (VFA); LP-30 increased (p < 0.05) total VFA (85 vs. 63 mM for LP-30 and CTL, respectively), molar proportions of acetate and propionate, and had lower C2:C3 than CTL (3.6 vs. 4.3, respectively); CO-300 decreased acetate and increased propionate, reducing C2:C3 (p < 0.001; 2.8 vs. 3.6 for CO-300 and average of other doses, respectively); PE-30 and PE-300 reduced NH3-N by 14% and increased total VFA by 29% compared with CTL (p < 0.05). Further in vivo investigations may consider L. pacari (LP-30), Copaifera spp. (CO-300) oleoresin and P. emarginatus oleoresin (PE-30 and PE-300) in diets with high inclusion of concentrate.  相似文献   

5.
Methane (CH4) can be mitigated through directly inhibiting methanogen activity and starving methanogens by hydrogen (H2) sink. Three types of mechanism (i.e. bromoethanesulphonate (BES), nitrate and emodin) and doses of CH4 mitigation agents were employed to investigate their pathways of CH4 inhibition. Results indicated that both BES and emodin inhibited CH4 production and altered H2 balance, which could be accompanied by decreased dry matter disappearance (DMD), fractional rate of gH2 formation, volatile fatty acid (VFA) production, ability to produce and use reducing equivalences and molecular H2, and increased final asymptotic gH2 production, time to the peak of gH2, discrete lag time of gH2 production and fermentation efficiency. However, emodin decreased gas volume produced by rapidly fermentable components of substrate and the rate of fermentation at early stage of incubation, while BES supplementation inhibited gas volume produced by both rapidly and slowly fermentable components of substrate and the rate of fermentation at middle or late stage of incubation. The nitrate supplementation inhibited CH4 production without affecting VFA profile, because of its dual role as H2 sink and being toxic to methanogens. Nitrate supplementation had more complicated pattern of fermentation, VFA production and profile and H2 balance in comparison to BES and emodin supplementation.  相似文献   

6.
甘草提取物对绵羊瘤胃体外发酵及甲烷产量的影响   总被引:3,自引:0,他引:3  
本试验旨在研究不同水平的甘草提取物对绵羊瘤胃体外发酵及甲烷产量的影响。选择3只安装有永久性瘤胃瘘管的卡拉库尔羊作为瘤胃液供体,通过体外产气法进行甘草提取物添加水平的筛选试验。以绵羊基础饲粮为底物,其中分别添加0(对照组)、0.5%、1.0%、3.0%、5.0%、7.0%的甘草提取物,分别培养6、9、12、15、18、21、24 h,研究其对瘤胃发酵参数(产气量、培养液pH、挥发性脂肪酸浓度、氨态氮浓度及甲烷产量)的影响,并应用多项指标综合指数进行评定。结果表明:24 h发酵结束时,5.0%组、7.0%组的产气量均显著低于对照组(P<0.05);甘草提取物对培养液pH和氨态氮浓度无显著影响(P>0.05);试验组乙酸、丙酸浓度(除0.5%组21 h)均低于对照组;发酵24 h结束时,7.0%组甲烷产量显著低于对照组(P<0.05);多项指标综合指数1.0%组>0.5%组>7.0%组>3.0%组>5.0%组。结果显示:本试验条件下,添加1.0%甘草提取物最有利于体外发酵。  相似文献   

7.
Effects of β‐cyclodextrin diallyl maleate (CD‐M) on methane production, ruminal fermentation and digestibility were studied both in vitro and in vivo. In in vitro study, diluted ruminal fluid (30 mL) was incubated anaerobically at 38°C for 6 and 24 h with or without CD‐M using hay plus concentrate (1.5:1) as a substrate. The CD‐M was added at different concentrations (0, 1.25, 2.5, 5.0 and 7.5 g/L). The pH of the medium and numbers of protozoa were not affected by the addition of CD‐M. Total volatile fatty acids were increased and ammonia‐N was decreased, molar proportion of acetate was decreased and propionate was increased (P < 0.05) by CD‐M. Methane was inhibited (P < 0.05) by 14–76%. The effect of CD‐M on methane production and ruminal fermentation was further investigated in vivo using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay and concentrate mixture (1.5:1) with or without CD‐M (2% of feed dry matter) as a supplement. Ruminal proportion of acetate tended to decrease and that of propionate was increased (P < 0.05) 2 h after CD‐M dosing. Total viable counts, cellulolytic, sulfate reducing, acetogenic bacteria and protozoa were unaffected while methanogenic bacteria were decreased (P < 0.05) by CD‐M. The plasma concentration of glucose was increased, whereas that of urea‐N was decreased (P < 0.05). Methane was inhibited (P < 0.05) from 36.4 to 30.1 L/kg dry matter intake by the addition of CD‐M. Apparent digestibilities of dry matter and neutral detergent fiber were not affected while that of crude protein was increased (P < 0.05) in the medicated steers. These data suggested that dietary supplementation of CD‐M decreased methane production and improved nutrient use.  相似文献   

8.
本试验以精料、青干草和单宁酸作为发酵底物,研究添加不同水平单宁酸对绵羊体外发酵参数和甲烷产量、干物质和粗蛋白质降解率的影响,以期为体内试验筛选适宜的单宁酸浓度,为富含单宁的粗饲料资源应用于反刍动物日粮配制及减少反刍动物养殖过程种甲烷排放提供科学依据。采用体外批次培养法开展研究,发酵底物为精料、青干草和单宁酸,设置底物的精粗比为3∶7。根据单宁酸添加量分为6组,单宁酸添加量分别为0、0.5%、1.0%、1.5%、2.0%、3.0%,发酵时间设置为3、6、12和24 h,每个处理3个重复,测定各培养时间pH、氨氮(NH3-N)浓度、挥发性脂肪酸(VFA)浓度、总产气量、甲烷产量、干物质和粗蛋白质降解率。结果显示,培养至3 h时,1.0%和2.0%单宁酸添加组pH显著高于对照组(P<0.05),其他时间点各组pH无显著差异(P>0.05);1.0%、2.0%和3.0%单宁酸添加组NH3-N浓度显著低于对照组(P<0.05);培养至6和24 h时,各处理组NH3-N浓度均显著低于对照组(P<0.05)。培养至6 h时,2.0%单宁酸添加组乙酸、丙酸、丁酸和总VFA浓度均显著低于对照组(P<0.05);培养至24 h时,1.0%、1.5%和3.0%单宁酸添加组的丙酸、丁酸和总VFA浓度均显著低于对照组(P<0.05);各单宁酸添加组4个时间点丙酸、丁酸、总VFA浓度的平均值均显著低于对照组(P<0.05)。培养至12、24 h时,各处理组总产气量与对照组差异不显著(P>0.05);培养至12 h时,2.0%组甲烷产量显著低于对照组、0.5%组和1.0%组(P<0.05);培养至24 h时,2.0%和3.0%组的甲烷产量显著低于对照组(P<0.05)。因此,添加单宁酸会显著降低体外发酵的NH3-N浓度,抑制VFA的产量,添加1.5%、2.0%的单宁酸能够显著降低瘤胃发酵甲烷产量,添加单宁酸的处理组粗蛋白质降解率显著低于对照组。  相似文献   

9.
The objective of this study was to investigate the effects of different sodium nitrate and disodium fumarate ratios on ruminal methane production, fermentation parameters, fatty acids profiles and microbial population in water buffalo in vitro in presence of α-linolenic acid. Three female water buffaloes (body weight of (650±50) kg) with permanent rumen fistula were selected as the donors of rumen contents. Treatments additives were prepared as sodium nitrate and disodium fumarate mixtures at ratios of 2:1, 1:1, 1:2. Control group without any sodium nitrate or disodium fumarate. All groups were added with 0.25 mg·mL-1 α-linolenic acid. The concentration of sodium nitrate and disodium fumarate mixtures was 1 mg·mL-1. The results showed that mehtane production were reduced with different ratios of sodium nitrate and disodium fumarate mixture, the average decrease was 90.63%. The total volatile fatty acid (TVFA) concentration and most rumen microorganisms population were significantly reduced (P<0.05), but the concentration of acetate, EPA and CLA, ratios of acetate to propionate ratio and UFA/SFA were significantly increased (P<0.05) with sodium nitrate and disodium fumarate mixtures at ratio of 2:1. 3) Sodium nitrate and disodium fumarate mixtures at ratio of 1:2 had no significant effect on TVFA content, fatty acid content and rumen microbial populaiton(P>0.05). 4) The concentrations of EPA, CLA and UFA/SFA ratio were increased (P<0.05) with sodium nitrate and disodium fumarate mixtures at ratio of 1:1, but Butyrivibrio fibrisolvens and atypical butyrivibrio populations were decreased. It can be concluded that different proportion of sodium nitrate and sodium fumarate mixture can cause methane reduction, the adverse effect of sodium nitrate on rumen fermentation can be alleviated by the increased proportion of disodium fumarate.  相似文献   

10.
本试验旨在研究体外条件下不同比例硝酸钠和延胡索酸二钠混合物对水牛瘤胃甲烷产量、体外发酵参数、脂肪酸组成及瘤胃微生物数量的影响。选取3头体重约为(650±50) kg安装永久性瘤胃瘘管的母水牛作为瘤胃液的供体动物。试验共设4个组,每组5个重复,硝酸钠和延胡索酸二钠的添加比例分别为2:1、1:1、1:2,对照组不添加任何两者混合物。每组均添加0.25 mg·mL-1的α-亚麻酸,试验组硝酸钠和延胡索酸二钠混合物浓度为1 mg·mL-1。结果表明:1)添加不同比例硝酸钠和延胡索酸二钠混合物均可显著降低甲烷含量(P<0.05),平均降幅为90.63%;2)高剂量硝酸钠与低剂量延胡索酸二钠(2:1)混合添加时会导致总挥发性脂肪酸(TVFA)含量和大部分瘤胃微生物的数量显著降低(P<0.05),乙酸含量、乙酸/丙酸、花生戊烯酸(EPA)含量、共轭亚油酸(CLA)含量和不饱和脂肪酸/饱和脂肪酸(UFA/SFA)显著升高(P<0.05);3)低剂量硝酸钠与高剂量延胡索酸二钠(1:2)混合时对TVFA含量、脂肪酸含量和瘤胃微生物数量无显著影响(P>0.05);4)添加硝酸钠延胡索酸二钠同剂量(1:1)能显著升高EPA、CLA含量和UFA/SFA(P<0.05),但显著降低了水牛瘤胃溶纤维丁酸弧菌和非典型丁酸弧菌数量。由此可见,添加不同比例硝酸钠和延胡索酸二钠混合物均可降低甲烷产量,随着延胡索酸二钠添加比例的增加可以缓解硝酸钠对瘤胃发酵的不利影响。  相似文献   

11.
本研究旨在探讨添加无患子皂甙(SAD)对瘤胃发酵及甲烷产量的影响。通过体外培养法,以玉米粉、羊草粉(50∶50)为底物,设置对照组(无添加)、添加底物量1.5%的茶皂素组(TS,正对照)和SAD(与TS相同皂甙量),测定培养12、24 h后各组产气量和甲烷产量,以及24 h培养液的pH值、挥发性脂肪酸浓度、氨态氮浓度和原虫数。结果表明:在12 h和24 h时,SAD组产气量均提高(P<0.01和P<0.05)。12 h时,SAD和TS组甲烷产量均显著降低(P<0.05),24 h时达到极显著(P<0.01)。SAD和TS组总挥发性脂肪酸浓度提高(P<0.01和P<0.05),SAD组乙酸和丙酸浓度增加(P<0.05和P<0.01),TS组丙酸浓度提高(P<0.05)。SAD组氨态氮浓度及培养液中原虫数极显著降低(P<0.01),TS组显著降低(P<0.05)。上述结果表明,添加SAD可促进瘤胃发酵,抑制原虫生长,减少甲烷产生。  相似文献   

12.
优化日粮配方是减少反刍动物甲烷产生的最有效途径.本研究利用体外瘤胃液发酵技术,对14种饲料原料(糠麸、植物蛋白和谷物)体外发酵性能相关性及产甲烷潜力进行评估.根据各成分的产甲烷量将饲料配方分为高产、中产和低产类型,然后进行体外发酵,以确定实际产甲烷量及其对消化率的影响.结果:3类原料中总可消化养分水平最高的分别是棕榈粕...  相似文献   

13.
本研究旨在通过体外发酵试验研究蜜蜂肽对瘤胃发酵参数及甲烷气体排放量的影响。本试验选用健康、体重[(40±3)kg]相近的高山美利奴羊(n=4)作为瘤胃液供体。试验采用单因子试验设计,共3个处理,在每千克干物质基础上,分别添加0、0.75、1.50 mg的蜜蜂肽,每个处理7个重复。发酵24 h后,冰水终止发酵,收集产气和发酵液,测定瘤胃发酵液pH,确定蜜蜂肽对发酵液气体产量、挥发性脂肪酸浓度以及部分微生物数量的影响。结果表明:体外发酵24 h,与不添加蜜蜂肽相比,添加0.75 mg蜜蜂肽能显著提高瘤胃内乙酸比例和乙酸/丙酸(P<0.05),显著降低丙酸比例(P<0.05),显著提高甲烷产量(P<0.05),有提高瘤胃pH(P=0.080)和普雷沃氏菌数量(P=0.078)的趋势。综上所述,在体外发酵24 h条件下,蜜蜂肽对绵羊瘤胃发酵有一定影响,能够调节绵羊瘤胃发酵模式。  相似文献   

14.
The relationship between in vitro rumen CH4 production of grass silages, using the gas production technique, and in vivo data obtained with the same cows and rations in respiration chambers was investigated. Silages were made from grass harvested in 2013 on May 6th, May 25th, July 1st and July 8th. The grass silages were used to formulate four different rations which were fed to 24 cows in early and late lactation, resulting in a slightly different dry matter intake (DMI; 16.5 kg/day vs. 15.4 kg/day). The experimental rations consisted of 70% grass silage, 10% maize silage, and 20% concentrates on a dry matter basis. Cows were adapted to the rations for 17 days before rumen fluid was collected via oesophageal tubing, and in vitro gas and CH4 production were analysed. In vitro total gas and CH4 production of the (ensiled) grass expressed as ml/g OM decreased with advancing maturity of the grass. The in vitro CH4 production after 48 hr of incubation expressed in ml/g OM did not correlate with the in vivo CH4 production expressed in g/kg organic matter intake or g/kg DMI (R2 = .00–.18, p ≥ .287). The differences in CH4 emission per unit of intake observed in vivo were rather small between the different rations, which also contributed to the observed poor relationship. Utilizing stepwise multiple regression improved the correlation only slightly. In vitro gas and CH4 production varied based on whether donor cows were previously adapted to the respective ration or not, suggesting that careful adaption to the experimental diet should be envisaged in in vitro gas and CH4 production experiments.  相似文献   

15.
体外法研究异麦芽寡糖对生长绵羊瘤胃发酵功能的影响   总被引:1,自引:0,他引:1  
采用批次培养的方法,研究了体外条件下日粮添加异麦芽寡糖对生长绵羊瘤胃发酵功能的影响。异麦芽寡糖的添加水平分别为0%(对照组)、0.20%、0.40%、0.60%、0.80%、1.00%。结果表明,日粮添加异麦芽寡糖可以提高培养液中挥发性脂肪酸(VFA)含量,降低培养液中的氨氮(NH3-N)含量和培养残渣中中性洗涤纤维(NDF)含量,但对培养液中菌体蛋白(BCP)含量的影响不确定。研究初步证明,日粮添加异麦芽寡糖可以在一定程度上提高生长绵羊的瘤胃发酵功能。  相似文献   

16.
以3只瘘管羊作为瘤胃液供体,用体外法研究可溶性淀粉和纤维素与滤纸纤维不同NSC/SC水平组合的体外发酵规律。底物使用可溶性淀粉与纯纤维素、可溶性淀粉与滤纸纤维,NSC/SC比例为:100∶0、70∶30、50∶50、30∶70、0∶100。结果表明:不同的NSC/SC水平组合比较,以70∶30组发酵状态最佳;滤纸纤维较纤维素总体发酵水平为低。  相似文献   

17.
旨在探讨利用体外产气法研究不同瘤胃降解蛋白平衡日粮(RDPB,g·kg-1 DM)对瘤胃发酵、总产气量和甲烷产量的影响.试验选用美国Ankom产气系统,采用随机区组试验设计,配置6种不同瘤胃降解蛋白平衡日粮,分别为日粮1(-20 g· kg-1 DM),日粮2(-10 g· kg-1 DM),日粮3(0 g· kg-1 DM),日粮4(10g·kg-1DM),日粮5(20 g·kg-1 DM)和日粮6(30 g· kg-1 DM),每组2个重复,培养期为24 h.结果表明:(1)本研究中6种类型日粮发酵液的pH、乙酸/丙酸、产气量和CH4产生量表现为日粮3(P<0.01)或日粮4(P<0.01)值最低.(2)挥发性脂防酸乙酸、丙酸、丁酸以及氨氮的浓度随着瘤冒降解平衡值的增加而增加,表明改变日粮瘤胃降解蛋白平衡可以影响瘤胃发酵.而瘤胃降解蛋白平衡对总挥发性脂肪酸以及原虫数量无显著影响.(3)日粮瘤胃降解蛋白平衡值影响不同时间点甲烷的浓度和24 h甲烷产量.其中以日稂4(P<0.05)甲烷总产量最低.由此可见,在体外培养条件下,改变日粮RDPB影响了瘤胃发酵液pH、氨态氮(NH3-N)及挥发性脂肪酸(VFA)浓度、总产气量、CH4产生量,综合考虑其对瘤胃发酵和甲烷产量等指标的影响,体外产气条件下适宜的RDPB水平为0~10g·kg-1 DM.  相似文献   

18.
纤维素、滤纸纤维分别与淀粉混合瘤胃体外发酵的比较   总被引:1,自引:0,他引:1  
以3只瘘管羊作为瘤胃液供体,用体外法研究可溶性淀粉和纤维素与滤纸纤维不同NSC/SC水平组合的体外发酵规律.底物使用可溶性淀粉与纯纤维素、可溶性淀粉与滤纸纤维,NSC/SC比例为:100:0、70:30、50:50、30:70、0:100.结果表明:不同的NSC/SC水平组合比较,以70:30组发酵状态最佳;滤纸纤维较纤维素总体发酵水平为低.  相似文献   

19.
日粮中添加延胡索酸对奶牛体外瘤胃发酵的影响   总被引:1,自引:0,他引:1  
利用体外培养试验,通过测定培养24h后培养液pH值、BCP、NH3-N、乙酸、丙酸、丁酸和TVFA等各项指标,综合评定了奶牛日粮中添加延胡索酸后对瘤胃发酵功能的影响。结果表明,与对照组比较,添加4mmol/L、7mmol/L的延胡索酸试验组的培养液pH值显著提高(P<0.05);添加4mmol/L和10mmol/L延胡索酸试验组BCP含量显著提高(P<0.05)。添加各剂量延胡索酸对培养液NH3-N含量均没有显著的影响。添加4mmol/L、7mmol/L处理组均提高了培养液的乙酸(P<0.05)和丙酸(P<0.05),添加10mmol/L处理组提高了丙酸(P<0.05)浓度,降低了丁酸(P<0.05)。  相似文献   

20.
利用体外培养试验,通过测定培养24h后培养液pH值、BCP、NH3-N、乙酸、丙酸、丁酸和TVFA等各项指标,综合评定了奶牛日粮中添加延胡索酸后对瘤胃发酵功能的影响.结果表明,与对照组比较,添加4mmol/L、7mmol/L的延胡索酸试验组的培养液pH值显著提高(P<0.05);添加4mmol/L和10mmol/L延胡索酸试验组BCP含量显著提高(P<0.05).添加各剂量延胡索酸对培养液NH3-N含量均没有显著的影响.添加4mmol/L、7mmol/L处理组均提高了培养液的乙酸(P<0.05)和丙酸(P<0.05),添加10mmol/L处理组提高了丙酸(P<0.05)浓度,降低了丁酸(P<0.05).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号