全文获取类型
收费全文 | 9406篇 |
免费 | 748篇 |
国内免费 | 10篇 |
专业分类
林业 | 217篇 |
农学 | 239篇 |
基础科学 | 48篇 |
733篇 | |
综合类 | 330篇 |
农作物 | 190篇 |
水产渔业 | 197篇 |
畜牧兽医 | 7660篇 |
园艺 | 110篇 |
植物保护 | 440篇 |
出版年
2023年 | 105篇 |
2021年 | 40篇 |
2020年 | 245篇 |
2019年 | 66篇 |
2018年 | 207篇 |
2017年 | 233篇 |
2016年 | 163篇 |
2015年 | 202篇 |
2014年 | 307篇 |
2013年 | 439篇 |
2012年 | 351篇 |
2011年 | 434篇 |
2010年 | 340篇 |
2009年 | 407篇 |
2008年 | 360篇 |
2007年 | 275篇 |
2006年 | 254篇 |
2005年 | 244篇 |
2004年 | 290篇 |
2003年 | 286篇 |
2002年 | 334篇 |
2001年 | 287篇 |
2000年 | 235篇 |
1999年 | 223篇 |
1998年 | 220篇 |
1997年 | 213篇 |
1996年 | 197篇 |
1995年 | 194篇 |
1994年 | 182篇 |
1993年 | 201篇 |
1992年 | 255篇 |
1991年 | 220篇 |
1990年 | 264篇 |
1989年 | 203篇 |
1988年 | 155篇 |
1987年 | 203篇 |
1986年 | 101篇 |
1985年 | 134篇 |
1984年 | 141篇 |
1983年 | 131篇 |
1982年 | 88篇 |
1981年 | 41篇 |
1980年 | 38篇 |
1979年 | 39篇 |
1978年 | 46篇 |
1977年 | 47篇 |
1976年 | 43篇 |
1974年 | 41篇 |
1971年 | 34篇 |
1969年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
981.
Triacylglycerols are the most concentrated storage form of energy for the mammalian organism. These lipids are synthesized and secreted by the liver and serve as a fuel for other tissues. This paper presents a brief review of the regulation of hepatic triacylglycerol synthesis and secretion. Particular attention will be given to the dissociation of the synthesis of triacylglycerols from that of the metabolically closely related nitrogenous phospholipids. Recent evidence is presented which suggests that triacylglycerol synthesis (and secretion) is regulated, at least partially, at the diacylglycerol branchpoint. 相似文献
982.
983.
The Effects of Fixation of the Ulna to the Radius in Young Foals 总被引:1,自引:0,他引:1
MICHAEL F. CLEM DVM MS RICHARD M. DeBOWES DVM MS Diplomateacvs JAMES P. DOUGLASS DVM MS Diplomateacvr HORST W. LEIPOLD DrMedVet PhD JAMES A. CHALMAN DVM 《Veterinary surgery : VS》1988,17(6):338-345
The effects of radioulnar fixation were studied in 21 Quarter horse foals by applying a bone plate to the caudal aspect of the proximal part of the ulna, with screws engaging both the radius and the ulna. The plates were applied at 1 month of age in six foals (group I), 5 months of age in six foals (group II), and 7 months of age in three foals (group III). Six foals underwent sham operations at 1 month of age to serve as controls (group IV). Ulnar dysplasia and elbow subluxation developed in all treated foals. The magnitude of ulnar dysplasia was inversely related to the patient's age at fixation and was accompanied by degenerative joint disease and lameness in foals undergoing fixation at 1 and 5 months of age. Removal of the fixation appliances 16 weeks after implantation in three foals from each of groups I and II failed to reverse the degree of ulnar dysplasia. Although foals undergoing fixation at 7 months of age (group III) were not lame, radiographic evidence of subluxation and subtle degenerative changes in the articular cartilage of the treated elbow did develop. Recommendations for avoidance of radioulnar fixation were developed from these observations. 相似文献
984.
985.
J. E. Van Dijk A. Fledderus J. M. V. M. Mouwen C. Holzhauer 《Veterinary research communications》1988,12(1):47-59
The significance of food allergy as a primary cause for gastrointestinal disturbances in domestic animals, especially calves and piglets, is discussed. The immunological backgrounds and pathogenesis are described in some detail. The clinical and pathological manifestations in animals are related to those in man. Diagnostic possibilities, therapy and prevention, as far as known in animals, are mentioned and, based on human experiences, further extensions are proposed. 相似文献
986.
Long-Term Follow-up of Partial Limb Amputation in 13 Horses 总被引:1,自引:0,他引:1
GREGORY R. CRAWLEY DVM MS BARRIE D. GRANT DVM MS DiplomateACVs MELINDA K. KRPAN DVM MS MICHAEL D. MAJOR DVM 《Veterinary surgery : VS》1989,18(1):52-55
Thirteen cases of partial limb amputation in horses were reviewed. Nine horses (69%) survived 18 to 111 months (mean, 41 months). Four unsuccessfully treated horses were euthanatized within 21 days of surgery. The horses' ages at amputation were 4 to 13 years (mean, 7.3 years). There was no predilection for the left or right limb nor for fore or hind limb involvement. Osteomyelitis in six horses (46%) was the most common cause for amputation. Severe, open, comminuted fractures of the third metacarpal bone that were impossible to stabilize by any currently available technique in four horses (31%) were the second most common cause for amputation. One gelding was salvaged because of his sentimental value, two horses were used as breeding stallions, and six were broodmares. One stallion lived 30 months, completed two breeding seasons, and started a third. The other stallion began breeding, but became sterile. Three of the mares have produced five foals. One mare died while in foal. One mare aborted near-term twin fetuses and died of uterine hemorrhage. One mare aborted twice before the femoral head ligament on the contralateral limb ruptured, and she was euthanatized. 相似文献
987.
988.
The Importance of Egg Protein in Reduced Protein Diets Designed for Dogs With Renal Failure 总被引:1,自引:0,他引:1
David J. Polzin DVM PhD Carl A. Osborne DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1988,2(1):15-21
The effects of two reduced-protein diets and a canine maintenance diet on renal function, nutrition, serum and urine acid-base and electrolyte values, and divalent ion metabolism were compared in Beagle dogs with induced chronic renal failure. Two reduced-protein (18%) diets differed in their protein sources. One 18% protein diet was formulated using egg protein as the only protein source. The other 18% protein diet was formulated using a mixture of animal and vegetable proteins. The 42% protein diet contained a mixture of animal and vegetable protein sources. Results of this study indicate that the egg-based and mixed protein-based diets had similar effects on most clinical and laboratory evaluations in dogs with chronic renal failure. However, the egg protein diet appeared to promote hyperchloremic metabolic acidosis. Both reduced-protein diets were beneficial in reducing azotemia, polyuria, hypermagnesemia, and fractional excretion of phosphorus compared with the 42% protein diet. 相似文献
989.
JAMES K. ROUSH DVM MS JAMES W. WILSON DVM MS DiplomateACVS 《Veterinary surgery : VS》1989,18(3):190-196
Osteotomies were created in the left body of the mandible of nine dogs and immediately stabilized with either a six hole dynamic compression bone plate or an intramedullary pin. Cortical bone healing and vascular supply were evaluated at weeks 2, 5, and 10 by microradiography, microangiography, and correlated histology of selected mandibular slices. Perforating arterioles from the buccal mucosa maintained vascular supply to rostral mandibular segments. The mandibular body rostral to the osteotomy site and caudal to the canine tooth suffered an interruption of vascular supply that was replaced by a temporary extraosseous supply during healing of the osteotomy. Intramedullary pin placement resulted in destruction of rostral teeth. There was an inflammatory response around the rostral portion of all intramedullary pins. Osteotomy sites involving tooth roots resulted in no disruption of the normal vascular or neural structures of the tooth pulp. 相似文献
990.
C M Cameron B J Van Biljon W J Botha P C Knoetze 《The Onderstepoort journal of veterinary research》1983,50(3):229-231
Immunization of ewes with oil emulsion toxoid followed by an aluminium phosphate-adsorbed toxoid both containing 10 Lf per dose, resulted in a very high antitoxin level in their lambs. Two injections of aluminium phosphate-adsorbed toxoid also imparted a passive immunity to lambs which is considered to be adequate to protect them against tetanus for 4 weeks after birth. 相似文献