全文获取类型
收费全文 | 31253篇 |
免费 | 1321篇 |
国内免费 | 10篇 |
专业分类
林业 | 1119篇 |
农学 | 905篇 |
基础科学 | 181篇 |
4715篇 | |
综合类 | 4123篇 |
农作物 | 1214篇 |
水产渔业 | 1194篇 |
畜牧兽医 | 16965篇 |
园艺 | 362篇 |
植物保护 | 1806篇 |
出版年
2021年 | 239篇 |
2020年 | 277篇 |
2019年 | 342篇 |
2018年 | 611篇 |
2017年 | 680篇 |
2016年 | 580篇 |
2015年 | 377篇 |
2014年 | 570篇 |
2013年 | 1687篇 |
2012年 | 894篇 |
2011年 | 1162篇 |
2010年 | 836篇 |
2009年 | 781篇 |
2008年 | 1116篇 |
2007年 | 1100篇 |
2006年 | 930篇 |
2005年 | 745篇 |
2004年 | 754篇 |
2003年 | 686篇 |
2002年 | 608篇 |
2001年 | 756篇 |
2000年 | 760篇 |
1999年 | 563篇 |
1998年 | 253篇 |
1997年 | 237篇 |
1995年 | 277篇 |
1992年 | 417篇 |
1991年 | 434篇 |
1990年 | 454篇 |
1989年 | 457篇 |
1988年 | 356篇 |
1987年 | 364篇 |
1986年 | 400篇 |
1985年 | 356篇 |
1984年 | 341篇 |
1983年 | 318篇 |
1979年 | 489篇 |
1978年 | 336篇 |
1977年 | 378篇 |
1976年 | 476篇 |
1975年 | 495篇 |
1974年 | 527篇 |
1973年 | 492篇 |
1972年 | 455篇 |
1971年 | 363篇 |
1970年 | 399篇 |
1969年 | 448篇 |
1968年 | 450篇 |
1967年 | 457篇 |
1966年 | 447篇 |
排序方式: 共有10000条查询结果,搜索用时 42 毫秒
991.
The percentual composition of unesterified fatty acids in M. longissimus dorsi was determined by means of gas chromatography, and its correlations with the given genotype and pork condition were studied. Polyene fatty acids recorded from the Piétrain race deviated (C-18:2, C-18:3, C-20:4) from values recorded from large white and improved land race pigs. Animals of PSE nature were like Piétrain probands, in that their monoene acids were higher and diene acids lower by percentage than the comparable values in animals of normal pork condition. 相似文献
992.
993.
PAMELA C. WAGNER M.S. D.V.M. GEORGE W. BAGBY M.D. § BARRIE D. GRANT D.V.M. M.S. ANTHONY GALLINA D.V.M. PH.D. † MARC RATZLAFF D.V.M. PH.D. ‡ RON SANDE D.V.M. PH.D. 《Veterinary surgery : VS》1979,8(1):7-12
The Cloward technique for intervertebral fusion was utilized on 12 horses ranging from 3 months to 2 years of age. Of the 12 horses, 9 had been diagnosed as having equine cervical vertebral malformation (CVM) or "wobbles," and 3 were normal controls. A large hole was drilled from the ventral border of the vertebral bodies spanning the intervertebral disc and the vertebral end plates of the 2 articulating vertebrae. Frozen homologous bone dowels of slightly larger diameter from equine cadaver ilia were inserted in the holes. No adverse postoperative complication arose. Clinical improvement was seen in all horses with CVM. Three months postoperatively, partial or complete fusion was evident radiographically in 11 of the 12 horses. Necropsies were performed 3–6 months postoperatively to evaluate the quality of the fusion. Cadaver manipulation demonstrated reduced intervertebral movement at the operative site in all cases. The articulations of the equine cervical spine can be operatively fused by the Cloward technique, and surgically induced trauma is minimal. This technique can be used for stabilizing subluxations and may be applicable for treating fractures and osteolytic processes that have weakened vertebrae. 相似文献
994.
DAVID STOLOFF D.V.M. M.S… ‡ HUGH C. BUTLER D.V.M. M.S. § MARK M. GUFFY D.V.M. M.S. † § HORST W. LEIPOLD D.V.M. PH.D. § 《Veterinary surgery : VS》1979,8(2):38-45
An 18-week study was conducted to evaluate orthotopic osteochondral transplantation of the proximal femur in the dog. Eighteen dogs were divided into 3 groups of 6 each. The first group received autografts, the second received fresh allografts, and the third received grafts that had been frozen in a bone bank for 24–28 days. The grafts were fixed in position using dynamic compression plates. The grafted limbs were maintained in a sling and thus were nonfunctional and non-weight bearing throughout the 18-week study. Postoperatively the dogs were given oral tetracycline to assess osteo- cyte viability. The dogs were radiographed at 2–week intervals and 1 dog in each group was euthanatized every 3 weeks. The femurs were examined using standard histopathologic and fluorescent labeling techniques. All femoral heads were luxated by the 2nd postoperative week. The bones of all the femoral heads underwent avascular necrosis and degenerative changes were present in the transplanted cartilage by the 6th postoperative week. During the first 18 weeks following transplantation there was little radiographic and histologic difference among the 3 types of grafts regarding the nature and rate of bone healing. Based on the data obtained from techniques utilized in this study, the femoral head, neck, and articular cartilage did not survive, while the femoral diaphysis did survive the transplantation process. Different techniques may alter to some degree the results obtained. 相似文献
995.
996.
ISOLATION OF
CHLAMYDIA PSITTACI
FROM CATS WITH CONJUNCTIVITIS 总被引:1,自引:0,他引:1
SUMMARY Chlamydia psittaci was repeatedly demonstrated in stained smears of conjunctival scrapings from a group of cats in a single household and in 5 instances the organism was isolated by yolk sac inoculation of 6-day-old specific pathogen free, embryonated hen eggs. Thirteen of 15 cats in the cattery developed conjunctivitis at various times over a 9-month period. The outstanding features of the disease were its severity, chronicity and refractoriness to treatment. Prolonged (2 week) treatment with tetracycline was required to effect clinical recovery. Nine of 14 cats in the household developed significant complement-fixing (CF) antibody titres (>128) to the chlamydia group antigen. A single serum from the owner had a titre of 32 although no associated illness was recognised. Of 134 serums collected from random source cats aged 1 month to 16 years, 17 (12.7%) also contained CF antibody to chlamydia group antigen. This is the first report of the isolation of chlamydia from cats with conjunctivitis outside North America and the first report to indicate general incidence figures for chlamydia infection of cats where vaccination is not used. 相似文献
997.
998.
999.
1000.