全文获取类型
收费全文 | 40755篇 |
免费 | 4717篇 |
国内免费 | 121篇 |
专业分类
林业 | 2003篇 |
农学 | 1576篇 |
基础科学 | 248篇 |
7508篇 | |
综合类 | 3983篇 |
农作物 | 1555篇 |
水产渔业 | 4476篇 |
畜牧兽医 | 20207篇 |
园艺 | 466篇 |
植物保护 | 3571篇 |
出版年
2021年 | 564篇 |
2020年 | 891篇 |
2019年 | 1440篇 |
2018年 | 1620篇 |
2017年 | 1775篇 |
2016年 | 1722篇 |
2015年 | 1374篇 |
2014年 | 1567篇 |
2013年 | 2452篇 |
2012年 | 1997篇 |
2011年 | 2109篇 |
2010年 | 1666篇 |
2009年 | 1296篇 |
2008年 | 1723篇 |
2007年 | 1540篇 |
2006年 | 1357篇 |
2005年 | 1278篇 |
2004年 | 1112篇 |
2003年 | 1154篇 |
2002年 | 989篇 |
2001年 | 1064篇 |
2000年 | 1081篇 |
1999年 | 813篇 |
1998年 | 323篇 |
1997年 | 342篇 |
1995年 | 294篇 |
1992年 | 477篇 |
1991年 | 556篇 |
1990年 | 481篇 |
1989年 | 456篇 |
1988年 | 439篇 |
1987年 | 447篇 |
1986年 | 406篇 |
1985年 | 435篇 |
1984年 | 379篇 |
1983年 | 320篇 |
1982年 | 264篇 |
1979年 | 416篇 |
1978年 | 322篇 |
1977年 | 322篇 |
1976年 | 311篇 |
1975年 | 327篇 |
1974年 | 357篇 |
1973年 | 347篇 |
1972年 | 320篇 |
1971年 | 272篇 |
1969年 | 301篇 |
1968年 | 274篇 |
1967年 | 331篇 |
1966年 | 310篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
By the radiographic examination of pet and wild birds, veterinary clinicians may relatively easily obtain additional information that can be used routinely in their everyday diagnostic and therapeutic work. The first part of the present review summarizes the basic technical conditions of radiological examinations, analyses the radiographic features of healthy birds, and describes the procedure and radiological indications of contrast radiography. 相似文献
92.
93.
M I Banton S S Nicholson P L Jowett M B Brantley C L Boudreaux 《Journal of the American Veterinary Medical Association》1987,191(7):827-828
Cattle from 2 herds developed copper toxicosis after the ingestion of chicken litter. The affected animals were adult Holstein cows and crossbred steers that ate 9 to 16 kg of litter/day. These cattle developed a sudden onset of weakness, depression, anorexia, icteric mucous membranes, and dark reddish brown urine. Liver copper concentrations in 2 cattle (1 from each herd) were 436 and 730 ppm. Results of copper analyses of chicken litter ranged from 620 to 920 ppm. Sodium molybdate and sodium thiosulfate were added to the ration of the dairy herd. Two cows with clinical signs of copper toxicosis recovered after being given additional sodium molybdate and thiosulfate supplements, orally. 相似文献
94.
95.
1. The endogenous avian leukosis virus (ev) loci present in 9 lines of domestic fowls have been partially characterised and the average heterozygosity of the loci in each line calculated. 2. Using these data an estimate of the coefficient of inbreeding of the lines was derived; this estimate of the extent of inbreeding is compared with the mating history of the lines. 3. This method provides the first means of directly assessing the degree of inbreeding of fowl lines: assumptions implicit in the method are discussed. 相似文献
96.
Caspe SG Moore DP Leunda MR Cano DB Lischinsky L Regidor-Cerrillo J Alvarez-García G Echaide IG Bacigalupe D Ortega Mora LM Odeón AC Campero CM 《Veterinary parasitology》2012,189(2-4):171-181
The Nc-Spain 7 isolate of Neospora caninum, which was newly obtained from an asymptomatic congenitally infected calf, demonstrated a similar virulence as Nc-1 strain in mouse models. The aim of this study was to characterize the pathogenesis of Nc-Spain 7 isolate in cattle after experimental infection at 65 days of gestation. For this purpose, thirteen pregnant heifers were divided into three groups as follows: group A: 7 heifers inoculated with 1×10(8) tachyzoites of Nc-Spain 7 isolate; group B: 4 heifers inoculated with 1×10(8) tachyzoites of Nc 1 strain; and group C: 2 heifers received PBS. Serum samples were collected weekly and heparinized blood samples were collected three times (0, 28 and 42 days after inoculation) by jugular venipuncture. Placenta and fetal tissue samples were collected at time of necropsy. Specific antibody response in the dams was tested by IFAT, indirect ELISA, and rNcGRA7 and rNcSAG4 based-ELISA. Specific antibody response in fetal fluids was tested by IFAT. IFN-γ production was measured after in vitro culture of PBMC and the supernatant was assessed using a commercial kit (BOVIGAM). A significant increase in N. caninum antibody responses was detected in groups A and B by IFAT and by i-ELISA from day 14 after inoculation onwards. Besides, antibody response against rNCGra7 protein was also detected in all inoculated heifers by rNcGra7-based ELISA. Four fetuses from group A and one from group B were aborted between 3 and 5 weeks after infection. In the recovered fetuses, only 3 out of 4 fetal fluids from fetuses of group A and 1 out of 3 of group B were seropositive by IFAT, but all of them were positive by PCR. Transplacental transmission could be determined in all fetuses from groups A and B by PCR and/or IHC. Heifers of group C and their fetuses remained negative by all techniques. The results of this study demonstrate that the NC-Spain 7 isolate could be transmitted transplacentally, and produced fetal death and abortion in cattle. 相似文献
97.
González Canga A Sahagún Prieto AM José Diez Liébana M Martínez NF Vega MS Vieitez JJ 《Veterinary journal (London, England : 1997)》2009,179(1):25-37
The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species. 相似文献
98.
Atrial fibrillation is a disorder of cardiac rhythmicity, and its importance in the horse depends on the underlying cause and the function of the horse. Before the decision is taken to start treatment, it has first to be ascertained whether treatment is worthwhile and whether the horse is an appropriate candidate for treatment. This article gives a short overview of current opinion on the cause and treatment of atrial fibrillation in the horse. The most used treatment at the moment, oral chinidine sulphate, is discussed. The hemodynamic consequences of atrial fibrillation and the response of a patient to treatment with chinidine sulphate are also discussed. 相似文献
99.
JiíMLKOVSK 《中国鸟类》2011,2(2)
山麻雀是一种广布的小型鸣禽,拉丁学名通常为Passer rutilans (Temminck).经作者考证,该种名发表于1836年12月31日,但在此之前,Gould已于1836年4月8日发表了该种并命名为Passer cinnamomeus.因此,根据动物命名法中的优先原则,该种应称作Passer cinnamomeus (Gould,1836).其公认的3个亚种也应分别称作P.cinamomeus rutilans (Temminck,1836),P.cinnamomeus intensior Rothschild,1922及P.cinnamomeus cinnamomeus (Gould,1836). 相似文献
100.
Tecles F Martínez Subiela S Bernal LJ Cerón JJ 《Veterinary journal (London, England : 1997)》2000,160(3):242-249
Whole blood has been compared with erythrocytes and plasma for spectrophotometric cholinesterase determination in the dog. Cholinesterase activity was characterized using two substrates: acetylthiocholine and butyrylthiocholine. Acetylcholinesterase was the only form of cholinesterase present on erythrocytes and hydrolysed only acetylthiocholine. Butyrylcholinesterase (pseudocholinesterase) was predominant in plasma, hydrolysing mainly butyrylthiocholine. Based on these results, a method based on the use of two substrates (acetylthiocholine for monitoring acetylcholinesterase and butyrylthiocholine for determining butyrylcholinesterase) in the same whole blood sample is recommended for canine cholinesterase analysis. This way of monitoring both enzymes can be easily automated, yielding good within (CVs < 5%) and between-run (CVs < 7%) precision. 相似文献