首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   588篇
  免费   71篇
  国内免费   37篇
林业   4篇
农学   3篇
  1篇
综合类   116篇
农作物   16篇
水产渔业   21篇
畜牧兽医   480篇
园艺   55篇
  2023年   9篇
  2022年   17篇
  2021年   31篇
  2020年   44篇
  2019年   41篇
  2018年   24篇
  2017年   34篇
  2016年   23篇
  2015年   18篇
  2014年   35篇
  2013年   30篇
  2012年   32篇
  2011年   35篇
  2010年   23篇
  2009年   20篇
  2008年   31篇
  2007年   17篇
  2006年   29篇
  2005年   36篇
  2004年   24篇
  2003年   23篇
  2002年   8篇
  2001年   12篇
  2000年   17篇
  1999年   13篇
  1998年   17篇
  1997年   6篇
  1996年   4篇
  1995年   4篇
  1994年   4篇
  1993年   3篇
  1992年   9篇
  1990年   1篇
  1989年   4篇
  1987年   3篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1981年   1篇
  1980年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1956年   4篇
排序方式: 共有696条查询结果,搜索用时 15 毫秒
1.
The effects of intramuscularly administered medetomidine and butorphanol (MB), and medetomidine, butorphanol, atropine (MBA) on glomerular filtration rate (GFR) were determined in six dogs as measured by 99m-Tc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) nuclear scintigraphy. Direct systolic, diastolic, and mean arterial blood pressures and heart rate were measured at regular time intervals before, during, and after GFR calculations. The mean GFR measurement following MB was significantly greater (4.44 ml/min/kg) than following MBA (3.82 ml/min/kg) or saline treatment (3.41 ml/min/kg). There was no significant difference between the mean GFR measurements following MBA injection and following saline injection. Diastolic and mean arterial pressures following MBA injection were significantly higher than the values recorded after either MB or saline alone. Heart rate following MB administration was significantly lower than that recorded for dogs receiving MBA or saline alone. The results of this study indicate that the administration of medetomidine in combination with butorphanol significantly increases total GFR in healthy dogs, while the administration of the combination of medetomidine, butorphanol, and atropine does not.  相似文献   
2.
将12只2~3岁健康绵羊分为Ⅰ组(3只)、Ⅱ组(6只)和Ⅲ组(3只),分别按2.5,5.0,10.0 g/kg体重的剂量,向瘤胃内注入50%D—L消旋体乳酸溶液,各处理组均出现酸中毒症状.乳酸酸中毒时,肾脏的损伤程度与瘤胃内注入乳酸的剂量水平有关.各处理组瘤胃内注入乳酸后,尿素氮显著升高.第Ⅰ组尿液pH下降迅速,恢复亦快;第Ⅱ组尿液pH下降和回升均较缓慢,而且出现大量蛋白质和血液;第Ⅲ组尿液除见第Ⅰ、Ⅱ组的变化外,还出现肌红蛋白、酮体和尿胆素原.  相似文献   
3.
2种组胺受体拮抗剂对低温诱发的肉鸡肺动脉高压的影响   总被引:1,自引:3,他引:1  
为探讨组胺H1受体拮抗剂扑尔敏和H2受体拮抗剂西咪替丁对低温诱发的肉鸡肺动脉高压的影响,并由此推测组胺在低温诱发的肉鸡肺动脉高压形成过程中的作用。140只17日龄AA肉鸡随机分为4组。(1)常温组:40只在常温条件下饲养(22~23℃),每日注射生理盐水2次;(2)低温组:40只在低温环境中饲养(9~11℃),每日注射生理盐水2次;(3)扑尔敏组:40只在低温环境中饲养(9~11℃),每日注射扑尔敏2次;(4)西咪替丁组:20只在低温环境中饲养(9~11℃),于24日龄至38日龄期间每日注射西咪替丁2次。分别于低温处理后1周(24日龄)、2周(31日龄)、3周(38日龄)、4周(45日龄)从常温组,低温组,扑尔敏组中各随机抽取10只,西咪替丁组在低温处理后2周(31日龄)、3周(38日龄)各随机抽取10只,称取体重,然后利用右心导管法测定肺动脉压(PAP),并测定红细胞压积(PCV),腹水心脏指数(AHI)。结果发现:(1)24日龄、31日龄、38日龄时,低温组肺动脉收缩压,舒张压显著高于(P<0105)或极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组肺动脉收缩压显著低于(P<0105)同日龄低温组。38日龄时西咪替丁组肺动脉收缩压,舒张压极显著低于(P<0101)同日龄低温组。(2)24日龄、31日龄、38日龄、45日龄时,低温组PCV极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组  相似文献   
4.
内毒素介导动物急性肾功能衰竭机理的试验研究   总被引:2,自引:0,他引:2  
为了阐明内毒素介导急性肾功能衰竭的机理,观察了内毒素性肾功能衰竭家兔血液凝固性变化和肾脏的病理形态学变化。与对照组家兔比较,模型组家兔血小板计数和血浆纤维蛋白原含量极显著降低(P<0 01),出血时间、凝血时间、凝血酶原时间和白陶土部分凝血活酶生成时间显著或极显著延长(P<0 05,P<0 01)。另一方面,内毒素注射在全部模型组家兔导致了弥漫性血管内凝血,71.4%的肾小球中发现了微血栓,肾小球纤维素密度指数达60 6%。此外,96.2%的肾小管上皮细胞变性坏死,84.1%的肾小管中有管型形成。对照组家兔均未发现这些病理变化。上述试验结果揭示,内毒素引发了弥漫性血管内凝血,而肾小球毛细血管内广泛形成的微血栓阻断了肾小球毛细血管血流,从而导致肾小球滤过率降低,这是内毒素介导急性肾功能衰竭的首要机理。此外,肾小管上皮细胞的变性、坏死可损害其重吸收和分泌功能,管型形成可阻塞肾小管管腔并增大肾球囊内的压力,这些也都是在内毒素介导急性肾功能衰竭发生发展过程中起重要作用的因素。  相似文献   
5.
This study investigated the effects of intrauterine growth restriction during late pregnancy on the ovine fetal renal function and renal antioxidant capacity. Eighteen ewes pregnant were randomly divided into control group (CG, ad libitum, 0.67 MJ ME·BW−0.75·day−1, n = 6), restricted group 1 (RG1, 0.18 MJ ME·BW−0.75·day−1, n = 6), and restricted group 2 (RG2, 0.33 MJ ME·BW−0.75·day−1, n = 6). At 140 days, the fetal blood, allantoic fluid and kidney tissue were collected to determinate fetal renal function and renal antioxidant capacity. The results showed that the fetal weight, kidney weight, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), aquaporin-2 (AQP-2) and aquaporin-3 (AQP-3), and total antioxidant capacity (T-AOC) in RG1 group were decreased compared with the CG (P < 0.05), but the contents of β2-Microglobulin (β 2-MG), cystatin C (Cys-C), filtered sodium excretion fraction (FENa), malondialdehyde (MDA), and hydroxyl radical (OH) in RG1 group were increased (P < 0.05). The impaired ovine fetal renal growth, antioxidant imbalance and dysfunction of glomerulus ultrafiltration, and the renal tubules reabsorption were induced by maternal malnutrition during late pregnancy.  相似文献   
6.
在培养液中加入不同浓度的Cd(10、20、40μmol/L)、Pb(10、20、40μmol/L)和Pb-Cd联合(分别为5、10、20μmol/L),来探讨铅镉对肾细胞的作用及可能机制。在显微镜下观察细胞形态、测定细胞凋亡率和细胞周期及上清液脂质过氧化指标。结果表明:20μmol/L以上染毒组细胞皱缩、体积变小,表面有细胞碎片,甚至呈泡沫状或树枝状;铅、镉单独和联合染毒组GSH—Px、SOD活性随染毒剂量的增加,呈逐渐下降趋势(P〈0.05).而MDA含量和凋亡率则呈升高趋势(P〈0.05),并存在剂量和时间效应。镉和铅也能使细胞周期停滞。Pb、Cd联合可加剧细胞损伤。  相似文献   
7.
A variety of laboratory tests are available to assist the clinician in the assessment of kidney health and function. The majority of widely used tests are indicative of altered renal function, not becoming abnormal until function is significantly compromised. These include serum urea and creatinine concentrations, serum electrolyte concentrations, urine specific gravity (USG), fractional electrolyte excretion ratios and symmetric dimethylarginine (SDMA) concentrations. Some of these parameters may also be affected by nonrenal disease. The results of a further group of tests can indicate renal damage, but do not reflect renal function. These include urine tubular enzyme concentrations, urine protein concentrations, urine neutrophil gelatinase-associated lipocalin (NGAL) concentrations and cytological abnormalities.  相似文献   
8.
本研究旨在评估短链脂肪酸在慢性肾衰竭患犬和健康犬中的水平,探究短链脂肪酸变化的原因及其对肾功能的影响。选取22例轻度慢性肾衰患犬(M-CRF组)、29例重度慢性肾衰患犬(S-CRF组)和26例健康对照犬(HC组),用16S rDNA测序技术分析肠道菌群多样性,气相色谱法检测粪中短链脂肪酸浓度。通过粪菌移植和补充丁酸钠给5/6肾摘除犬,观察肠道菌群及丁酸钠对肾功能影响。结果显示:1)S-CRF组肠道菌群多样性指标观察物种数及Simpson指数低于HC组(P<0.05),PCoA分析显示,S-CRF组肠道菌群与M-CRF、HC组有差异。2)LEfSe分析显示,S-CRF组和HC组间大量差异菌群,拟杆菌科、拟杆菌属及假单胞菌科等7个菌种富集于S-CRF组,普氏杆菌科、梭菌科、普氏杆菌属及普拉梭菌属等11个菌种富集于HC组。CCA分析发现富集于S-CRF组菌种丰度与肾功能指标呈正相关。3)S-CRF组粪中乙酸、丙酸及丁酸浓度均显著低于HC组和M-CRF组,M-CRF组丁酸浓度显著低于HC组(P<0.05),且丁酸浓度与血中胱抑素C(Cys-c)、肌酐(Cr)及尿素氮(BUN)等肾功能指标呈负相关(r值分别为-0.451、-0.583和-0.514,P<0.01)。4)与慢性肾衰模型组(5/6 Nx组)比较,慢性肾衰犬给与丁酸钠8周后,血清Cr和BUN显著降低(P<0.05);粪菌移植8周后,血清Cr和BUN显著升高(P<0.05),丁酸钠可回调血清Cr和BUN水平。综上表明,慢性肾衰竭患犬肠道菌群多样性降低,菌群结构及丰度改变,粪中短链脂肪酸浓度降低,这些变化可加剧肾功能障碍。为犬慢性肾衰竭的防治提供新的理论依据。  相似文献   
9.
A 20-year-old Warmblood gelding presented for evaluation and treatment of ventral oedema and azotaemia of unknown aetiology. On presentation, a diastolic heart murmur was appreciated and echocardiography revealed moderate aortic insufficiency due to chronic degenerative valve disease. The horse was hospitalised and failed to respond to oral and i.v. fluids and diuretics. Following discontinuation of all fluid and diuretic therapy, the horse became acutely agitated and developed monomorphic ventricular tachycardia. The ventricular tachycardia spontaneously converted to normal sinus rhythm, however the heart murmur changed in timing to a right basilar continuous murmur and bounding jugular pulses were noted. Repeat echocardiogram revealed an aorto-cardiac fistula with dissection into the basilar interventricular septum and left-sided chamber volume overload that was not previously present. Attempts at stabilisation were unsuccessful and euthanasia was elected. Post-mortem examination confirmed chronic renal disease of unknown aetiology in addition to an aorto-cardiac fistula originating from the right sinus of Valsalva with subsequent dissection into the basilar interventricular septum.  相似文献   
10.
ObjectiveTo compare induction times and physiological effects of etorphine–azaperone with etorphine–midazolam immobilization in African buffaloes.Study designRandomized crossover study.AnimalsA group of 10 adult buffalo bulls (mean body weight 353 kg).MethodsEtorphine–azaperone (treatment EA; 0.015 and 0.15 mg kg–1, respectively) and etorphine–midazolam (treatment EM; 0.015 and 0.15 mg kg–1, respectively) were administered once to buffaloes, 1 week apart. Once in sternal recumbency, buffaloes were instrumented and physiological variables recorded at 5 minute intervals, from 5 minutes to 20 minutes. Naltrexone (20 mg mg–1 etorphine dose) was administered intravenously at 40 minutes. Induction (dart placement to recumbency) and recovery (naltrexone administration to standing) times were recorded. Arterial blood samples were analysed at 5 and 20 minutes. Physiological data were compared between treatments using a general linear mixed model and reported as mean ± standard deviation. Time data were compared using Mann-Whitney U test and reported as median (interquartile range) with p ≤ 0.05.ResultsActual drug doses administered for etorphine, azaperone and midazolam were 0.015 ± 0.001, 0.15 ± 0.01 and 0.16 ± 0.02 mg kg–1, respectively. Induction time for treatment EA was 3.3 (3.6) minutes and not different from 3.2 (3.2) minutes for treatment EM. The overall mean arterial blood pressure was significantly lower for treatment EA (102 ± 25 mmHg) than that for treatment EM (163 ± 18 mmHg) (p < 0.001). The PaO2 for treatment EA (37 ± 12 mmHg; 5.0 ± 1.6 kPa) was not different from that for treatment EM (43 ± 8 mmHg; 5.8 ± 1.1 kPa). Recovery time was 0.8 (0.6) minutes for treatment EA and did not differ from 1.1 (0.6) minutes for treatment EM.Conclusions and clinical relevanceTreatment EA was as effective as treatment EM for immobilization in this study. However, systemic arterial hypertension was a concern with treatment EM, and both combinations produced clinically relevant hypoxaemia. Supplemental oxygen administration is recommended with both drug combinations.  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