全文获取类型
收费全文 | 1571篇 |
免费 | 169篇 |
国内免费 | 155篇 |
专业分类
林业 | 59篇 |
农学 | 39篇 |
基础科学 | 11篇 |
36篇 | |
综合类 | 466篇 |
农作物 | 38篇 |
水产渔业 | 282篇 |
畜牧兽医 | 873篇 |
园艺 | 76篇 |
植物保护 | 15篇 |
出版年
2024年 | 5篇 |
2023年 | 25篇 |
2022年 | 61篇 |
2021年 | 77篇 |
2020年 | 67篇 |
2019年 | 107篇 |
2018年 | 46篇 |
2017年 | 98篇 |
2016年 | 90篇 |
2015年 | 63篇 |
2014年 | 60篇 |
2013年 | 106篇 |
2012年 | 111篇 |
2011年 | 98篇 |
2010年 | 82篇 |
2009年 | 66篇 |
2008年 | 64篇 |
2007年 | 74篇 |
2006年 | 68篇 |
2005年 | 70篇 |
2004年 | 63篇 |
2003年 | 48篇 |
2002年 | 42篇 |
2001年 | 42篇 |
2000年 | 28篇 |
1999年 | 23篇 |
1998年 | 18篇 |
1997年 | 27篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 14篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有1895条查询结果,搜索用时 0 毫秒
1.
Jamie S. Harmon Kim G. Michelsen Dr. Mark A. Sheridan 《Fish physiology and biochemistry》1991,9(4):361-368
Trialcylglycerol (TG) lipase was isolated and partially purified from rainbow trout liver. Triacylglycerol lipase activity was assayed by measuring14C-oleic acid release from14C-triolein.14C-oleic acid release was linear for up to two hours. Optimal activity occurred at pH 7.0 and 15°C. Most of the lipase activity was recovered in the cytosolic fraction. A 27,000-fold purification was achieved after Sepharose (Bio-gel A 0.5 M, 200–400 mesh) chromatography of a resuspended 20% ammonium sulfate fraction. The molecular weight of the trout hepatic lipase as determined by size-exclusion chromatography and by SDS-polyacrylamide gel electrophoresis was 40–43 kD. Lipase-mediated hydrolysis of TG resulted in the production of diacylglycerols, monoacylglycerols, and fatty acids. Kinetic analysis indicated that Vmax=0.016 nmol/h/mg protein and that Km=0.28 mM triolein. Lipolytic activity was enhanced in the presence of cAMP/ATP-Mg2+. These results suggest that the liver of trout possesses a neutral TG lipase that is responsible for mobilizing stored TG and is catalytically activated by phosphorylation.A part of this work was presented at the Annual Meeting of the American Society of Zoologists, December 26–30, 1990, San Antonio, TX. 相似文献
2.
3.
4.
[目的]对浙江省山区河道护坡植物枫杨进行耐淹性研究。[方法]分别测定生长在河岸和河道水流中的枫杨叶片的气孔导度和膜保护酶活性。[结果]枫杨树种在淹水条件下气孔导度比旱生条件下增加了52.89%,SOD和POD活性分别减少了17.1%和25.8%,MDA含量增加了18.48%。[结论]枫杨植株在山区河道消落带中具有较强的耐淹性。 相似文献
5.
才项吉 《青海畜牧兽医杂志》2012,42(3):7-8
应用硝氯粉和肝蛭净两种药物,采取口服投药方式,分不同剂量,在绵羊肝片吸虫驱虫方面做了对比试验。结果表明:硝氯粉按5mg/kg体重驱虫,肝片吸虫虫卵减少率96.85%;肝蛭净按12mg/kg体重驱虫,虫卵减少率96.74%;二者的驱虫效果差异不大,但在实际操作中,硝氯粉剂量稍大会出现中毒反应,剂量过小则效果不佳,硝氯粉剂量较难控制。建议养畜户在绵羊肝片吸虫驱虫时最好用肝蛭净。 相似文献
6.
Extract Scouring syndromes constitute a major disease group in dairy calves in New Zealand. 相似文献
7.
FREDRIK E. HOPPE DVM PHD DAVE A. HAGER DVM PAUL W. POULOS JR. DVM PHD STINA EKMAN DVM P. G. LINDGREN MD PHD 《Veterinary radiology & ultrasound》1986,27(4):99-101
A manual, ultrasound-guided biopsy technique was compared to a new automatic method using a new biopsy device. The liver and the left kidney of 10 dogs were biopsied using the two methods. The specimens from the biopsies were compared for size and quality. Results demonstrate that larger and higher quality samples were obtained with the new automatic method. 相似文献
8.
MARTIN GUILLOT MARC-ANDRÉ D'ANJOU KATE ALEXANDER CHRISTIAN BÉDARD MICHEL DESNOYERS GUY BEAUREGARD JÉRÔME R. E. DEL CASTILLO 《Veterinary radiology & ultrasound》2009,50(5):513-518
While abdominal ultrasound and ultrasound-guided fine-needle aspiration cytology are often combined to help determine the type of liver disease in dogs, little is known about the relationship that may exist between the results of these tests. We hypothesized that specific sonographic findings, or combinations of findings, may predict results of liver ultrasound-guided fine-needle aspiration cytology. Hepatic and extrahepatic sonographic findings were recorded prospectively using a standardized form in 70 dogs with clinically suspected liver disease and in which liver ultrasound-guided fine-needle aspiration cytology was performed. The predictive value of sonographic findings in regard to the category of cytology results was assessed with stepwise logistic regression analysis. Sonographic detection of a hepatic mass (≥3 cm; risk ratio [RR] 3.83, 95% Wald confidence intervals [95% CI] 2.42–3.93, P =0.0036), ascites (RR 3.82, 95% CI 1.94–4.28, P =0.0044), abnormal hepatic lymph node(s) (RR 3.01, 95% CI 1.22–4.88, P =0.0262), and abnormal spleen (RR 3.26, 95% CI 1.20–3.85, P =0.0274) were the most predictive of liver neoplasia on cytology. Conversely, sonographic detection of hepatic nodules (<3 cm; RR 1.97, 95% CI 0.95–2.96, P =0.0666) was most predictive of vacuolar hepatopathy on cytology. In dogs with suspected liver disease, several sonographic findings, alone or combined, are thus predictive of liver ultrasound-guided fine-needle aspiration cytology results. In the light of the fact that ultrasound-guided fine-needle aspiration cytology of the liver has limitations, these predictabilities could influence the selection of diagnostic tests to reach a reliable diagnosis. 相似文献
9.
10.
研究云南松松塔乙醇提取物(PEA)和碱水提取醇沉物(PED)对H22实体瘤小鼠的抑瘤作用。建立H22实体瘤小鼠模型,随机分组,灌胃给药,1次/d,给药10d。末次给药24h后,取血检测γ干扰素(IFN-γ)、白细胞介素-2(IL-2)、白细胞介素-4(IL-4)和白细胞介素-10(IL-10)含量;剥离肿瘤组织并称重,计算抑瘤率;检测肿瘤组织匀浆中环氧化酶-2(COX-2)和前列腺素E2(PGE2)含量;石蜡包埋HE染色观察肿瘤细胞病理组织学变化。结果显示,PEA和PED各剂量组小鼠平均肿瘤重量较模型组显著减小;最大抑瘤率分别达46.11%和58.05%。PEA和PED各剂量组小鼠外周血中IFN-γ和IL-2含量较模型组显著升高;IL-4和IL-10含量较模型组显著降低。PEA和PED各剂量组小鼠肿瘤组织中COX-2和PGE2含量较模型组显著减少;给药组正常肿瘤组织减少,有出血和坏死,脂肪组织增多。结果表明,PEA和PED可抑制H22实体瘤小鼠的肿瘤生长,其机制与调节Th1/Th2细胞平衡和抑制COX-2与PGE2的表达有关。 相似文献