全文获取类型
收费全文 | 220484篇 |
免费 | 11846篇 |
国内免费 | 148篇 |
专业分类
林业 | 9272篇 |
农学 | 7287篇 |
基础科学 | 1387篇 |
28507篇 | |
综合类 | 34961篇 |
农作物 | 8640篇 |
水产渔业 | 11281篇 |
畜牧兽医 | 113414篇 |
园艺 | 3043篇 |
植物保护 | 14686篇 |
出版年
2020年 | 1871篇 |
2019年 | 2236篇 |
2018年 | 3261篇 |
2017年 | 3705篇 |
2016年 | 3399篇 |
2015年 | 2938篇 |
2014年 | 3683篇 |
2013年 | 8940篇 |
2012年 | 6612篇 |
2011年 | 8131篇 |
2010年 | 5401篇 |
2009年 | 5455篇 |
2008年 | 8000篇 |
2007年 | 7663篇 |
2006年 | 7172篇 |
2005年 | 6615篇 |
2004年 | 6341篇 |
2003年 | 6493篇 |
2002年 | 5957篇 |
2001年 | 7002篇 |
2000年 | 6973篇 |
1999年 | 5646篇 |
1998年 | 2388篇 |
1997年 | 2323篇 |
1996年 | 2163篇 |
1995年 | 2586篇 |
1994年 | 2241篇 |
1993年 | 2167篇 |
1992年 | 4362篇 |
1991年 | 4601篇 |
1990年 | 4550篇 |
1989年 | 4556篇 |
1988年 | 4166篇 |
1987年 | 4144篇 |
1986年 | 4195篇 |
1985年 | 3995篇 |
1984年 | 3249篇 |
1983年 | 2904篇 |
1982年 | 1986篇 |
1979年 | 2926篇 |
1978年 | 2339篇 |
1977年 | 1974篇 |
1976年 | 1983篇 |
1975年 | 2096篇 |
1974年 | 2487篇 |
1973年 | 2559篇 |
1972年 | 2441篇 |
1971年 | 2191篇 |
1970年 | 2222篇 |
1969年 | 2135篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
171.
A P Davidson 《Veterinary Clinics of North America: Small Animal Practice》2001,31(2):411-420
The practice of small animal theriogenology is rewarding, but frustrations exist concerning technologic advances as compared with other species. Reproductive clinicians striving to practice good quality medicine readily identify topics of common concern: causes that are not identified or therapeutics that are not available or applicable. Improved collaboration among theriogenologists specializing in small animal practice is evidenced by growing attendance at national and international scientific meetings, increased scientific publications, and internet communications. 相似文献
172.
Y Sugawara K Hirasawa M Takeda J S Han K Doi 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1991,53(3):463-468
One-month-old Syrian hamsters of the APA and Std: golden strains were inoculated intraperitoneally with 10(5) PFU/head of the D variant of encephalomyocarditis (EMC) virus and examined virologically and pathologically up to 7 days after inoculation. APA hamsters developed apparent hyperglycemia due to pancreatic islet cell damage while Std:golden hamsters did not. Hamsters of both strains showed clear histopathologic changes in the testis with prominent viral replication as well as in the brain, heart and exocrine pancreas. The susceptibility to EMC virus-infection was higher in males than in females and in APA than in Std: golden hamsters. 相似文献
173.
L.E. Young D.H. Bartram M. Diamond A. Gregg R.S. Jones 《Veterinary anaesthesia and analgesia》1991,18(Z1):171-174
174.
The association between ocular squamous cell tumors and various measures of solar radiation was evaluated for 2,775 contemporaneous Hereford cattle. The animals were from 34 herds located in 21 states in the United States and in one Canadian province. Examinations and photographs were made of the eyes of all cows and heifers in a herd; 33 herds were examined between June and August 1957 and 1 herd was examined in 1958. Solar radiation was measured by altitude and mean annual hours of sunshine applying to an individual herd, and global radiation, a cloudiness index, and elevation of nearby National Weather Service stations. All measures of solar radiation provided evidence of a significant association between increasing risks of developing cancer eye and increasing levels of radiation; adjustments were made for possible confounding effects of age and corneoscleral pigmentation. Associations were evident whether affliction was defined as the occurrence of any type of tumor (ie, plaque, papilloma, or carcinoma), or as the occurrence of only papilloma or carcinoma. Average ages of affected cattle also tended to be lower at high radiation levels than at low levels, further supporting the hypothesis that solar radiation has an important role in the development of this disease. In view of the heritability of eye pigmentation and its inhibitory effect on lesions, cancer eye may be controlled by selective breeding for increased pigmentation in and around the eye to afford protection against the harmful effects of incident UV radiation. 相似文献
175.
176.
177.
L A Janssens 《Veterinary surgery : VS》1991,20(4):274-278
Seven foci of pain (trigger points) were identified in the triceps brachii, infraspinatus, adductor-pectineus, peroneus longus, gluteus medius, ileocostorum lumborum, and quadriceps femoris muscles in 48 lame dogs. The dogs had been lame for 1 day to 150 weeks (mean, 24 weeks). Thirty-one dogs had been treated unsuccessfully with corticosteroids, nonsteroidal anti-inflammatory drugs, analgesics, or acupuncture. Palpating the trigger points induced severe pain. Treatment consisted of weekly stimulation of the trigger points by needling or injection of a local anesthetic. The mean treatment period was 2.8 weeks. Excellent results and complete recovery were observed in 34 dogs (60%). 相似文献
178.
An ammonium sulfate fraction of Taenia hydatigena cyst fluid (ThFAS) was further fractionated by hydrophobic interaction chromatography, using alkylagarose and omega-amino alkylagarose columns, in an effort to isolate and purify a specific diagnostic antigen in the ThFAS preparation. The less than 12 kDa antigen was found to have an affinity for immobilized alkanes with chain length of six carbons or greater. The antigen was recovered in an ethylene glycol eluate from a hexylagarose column then analyzed by Western blot; it reacted with bovine and human cysticercosis infection sera and with specific monoclonal antibodies but not with control sera or fascioliasis infection sera. When the eluate was used as coating antigen in a plate ELISA assay no false positive reactions were seen in sera from cattle infected with Fasciola hepatica; false positive reactions were observed for the unfractionated ThFAS antigen preparation. 相似文献
179.
Thyroid scintigraphy in small animals 总被引:1,自引:0,他引:1
180.