全文获取类型
收费全文 | 76012篇 |
免费 | 4158篇 |
国内免费 | 42篇 |
专业分类
林业 | 3425篇 |
农学 | 2781篇 |
基础科学 | 542篇 |
9343篇 | |
综合类 | 11689篇 |
农作物 | 2817篇 |
水产渔业 | 3811篇 |
畜牧兽医 | 39361篇 |
园艺 | 992篇 |
植物保护 | 5451篇 |
出版年
2018年 | 1134篇 |
2017年 | 1205篇 |
2016年 | 1137篇 |
2015年 | 974篇 |
2014年 | 1235篇 |
2013年 | 3005篇 |
2012年 | 2302篇 |
2011年 | 2743篇 |
2010年 | 1825篇 |
2009年 | 1876篇 |
2008年 | 2853篇 |
2007年 | 2597篇 |
2006年 | 2537篇 |
2005年 | 2314篇 |
2004年 | 2403篇 |
2003年 | 2350篇 |
2002年 | 2230篇 |
2001年 | 2542篇 |
2000年 | 2540篇 |
1999年 | 2069篇 |
1998年 | 952篇 |
1997年 | 861篇 |
1996年 | 815篇 |
1995年 | 908篇 |
1994年 | 869篇 |
1993年 | 804篇 |
1992年 | 1605篇 |
1991年 | 1626篇 |
1990年 | 1753篇 |
1989年 | 1585篇 |
1988年 | 1524篇 |
1987年 | 1405篇 |
1986年 | 1435篇 |
1985年 | 1392篇 |
1984年 | 1181篇 |
1983年 | 1059篇 |
1982年 | 651篇 |
1979年 | 1040篇 |
1978年 | 817篇 |
1977年 | 735篇 |
1976年 | 690篇 |
1975年 | 742篇 |
1974年 | 788篇 |
1973年 | 850篇 |
1972年 | 831篇 |
1971年 | 774篇 |
1970年 | 741篇 |
1969年 | 757篇 |
1967年 | 671篇 |
1966年 | 647篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Prassinos NN Papazoglou LG Adamama-Moraitou KK Galatos AD Gouletsou P Rallis TS 《The Veterinary record》2003,153(3):81-85
Congenital anorectal abnormalities were diagnosed in three male and three female dogs. One dog had anal stenosis, three had a persistent anal membrane, and the other two had an imperforate anus associated with a rectovaginal fistula. Five of the dogs were treated surgically, and four of them which were followed up for periods ranging from one to five years continued to pass faeces normally. 相似文献
992.
Dispas M Schynts F Lemaire M Letellier C Vanopdenbosch E Thiry E Kerkhofs P 《The Veterinary record》2003,153(7):209-212
During a field trial to evaluate the efficacy of repeated vaccinations with bovine herpesvirus type 1 (BHV-1) marker vaccines, a glycoprotein E (gE)-negative BHV-1 strain was isolated from the nasal secretions of two cows, eight months after vaccination with a gE-negative live-attenuated vaccine, initially given intranasally, then intramuscularly. The strain isolated was characterised using immunofluorescence, restriction analysis and PCR. All the techniques used identified the isolated virus as a gE-negative BHV-1 phenotypically and genotypically identical to the Za strain used as a control. 相似文献
993.
994.
Wilmink JM Veenman JN van den Boom R Rutten VP Niewold TA Broekhuisen-Davies JM Lees R Armstrong S van Weeren PR Barneveld A 《Equine veterinary journal》2003,35(6):561-569
REASONS FOR PERFORMING STUDY: Wound healing proceeds faster in ponies than in horses and complications during healing, such as wound infection, occur less frequently in ponies. Earlier studies suggested that this difference might be related to differences in the initial post traumatic inflammatory response. HYPOTHESIS: That polymorphonuclear leucocyte (PMN) function and profiles of humoral factors in local inflammatory processes are different in horses and ponies. METHODS: PMNs were isolated from venous blood of horses and ponies. Chemotaxis and reactive oxygen species (ROS) production was determined. Tissue cages were implanted in limbs and necks of horses and ponies and injected with carrageenan and, 3 weeks later, with LPS. In sequential samples of inflammatory exudate, the numbers of macrophages and PMNs and the production of PGE2, TNFalpha, IL-1, IL-6 and chemoattractants were determined. RESULTS: In vitro ROS production of PMNs was significantly higher in ponies than in horses, whereas in vitro PMN chemotaxis was significantly lower in ponies. In the tissue cages for both stimuli, the production of IL-1 and chemoattractants was significantly higher in ponies than in horses and remained so towards the end of the observation period in ponies. CONCLUSIONS: This study demonstrated a higher production of various inflammatory mediators by pony leucocytes. Despite the lower in vitro chemotaxis of pony PMNs, this higher in vivo production resulted in a stronger initial inflammatory response in ponies, as has been reported in studies on wound healing, through the attraction of leucocytes and triggering of the production of other cytokines. A stronger initial inflammation may promote healing by more rapid elemination of contaminants and earlier transition to repair. POTENTIAL RELEVANCE: Modulation of the initial inflammatory response might therefore be a valid option for therapeutic intervention in cases of problematic wound healing. Further, the intraspecies differences in leucocyte function may have an impact on many fields in equine medicine. 相似文献
995.
Kóbori L Németh T Nemes B Dallos G Sótonyi P Fehérvári I Patonai A Slooff MJ Járay J De Jong KP 《Acta veterinaria Hungarica》2003,51(4):529-537
Hepatic artery thrombosis is a major cause of graft failure in liver transplantation. Use of donor interponates are common, but results are controversial because of necrosis or thrombosis after rejection. Reperfusion injury, hypoxia and free radical production determinate the survival. The aim of the study was to create an 'ideal' arterial interponate. Autologous, tubular graft lined with mesothelial cells, prepared from the posterior rectus fascia sheath, was used for iliac artery replacement in eight mongrel dogs for six months under immunosuppression. Patency rate was followed by Doppler ultrasound. Eight grafts remained patent and another two are patent after one year. The patency rate was good (median Doppler flow: 370 cm/sec) and there was no necrosis, thrombosis or aneurysmatic formation. The grafts showed viable morphology with neoangiogenesis, appearance of elastin, smooth muscle and endothelial cells. Electron microscopy showed intact mitochondrial structures without signs of hypoxia. Tissue oxygenation was good in all cases with normal (< 30 ng/ml) myeloperoxidase production. In conclusion, this autologous graft presents good long-term patency rate. Viability, arterialisation and low thrombogenicity are prognostic factors indicating usability of the graft in the clinical practice without the risk of rejection. Further investigations such as cell cultures and standardisation are necessary. 相似文献
996.
Evaluation of flunixin meglumine as an adjunct treatment for diarrhea in dairy calves 总被引:2,自引:0,他引:2
Barnett SC Sischo WM Moore DA Reynolds JP 《Journal of the American Veterinary Medical Association》2003,223(9):1329-1333
OBJECTIVE: To assess the use of flunixin meglumine as an adjunct treatment for diarrhea in calves. DESIGN: Clinical trial. ANIMALS: 115 calves with diarrhea that were 1 to 21 days old at enrollment. PROCEDURE: Calves that developed diarrhea were randomly assigned to receive no flunixin meglumine (controls), a single dose of flunixin meglumine (2.2 mg/kg [1.0 mg/lb]), or 2 doses of flunixin meglumine administered 24 hours apart. Serum IgG concentration and PCV were measured prior to enrollment in the trial. Calves were evaluated daily to determine rectal temperature, fecal consistency, demeanor, and skin elasticity score. The primary analytic outcome was days of sickness (morbid-days). RESULTS: Calves with fecal blood and treated with a single dose of flunixin meglumine had fewer morbid-days and antimicrobial treatments, compared with controls. Although not significant, calves given 2 doses of flunixin meglumine in 24 hours had fewer morbid-days than untreated control calves. Regardless of severity of diarrhea, calves without fecal blood did not benefit from the use of flunixin. For calves with fecal blood, failure of passive transfer (low serum IgG concentration) was an independent risk factor for increased morbid-days. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with a single dose of flunixin meglumine resulted in fewer antimicrobial treatments and morbid-days in calves with fecal blood. As observed in other studies, calves with failure of passive transfer were at high risk for poor outcomes. This emphasizes the importance of developing and implementing effective colostrum delivery programs on dairy farms. 相似文献
997.
Several clinical variables were compared in two groups of 15 horses recovering from resection and anastomosis of a strangulated small intestine; 15 were treated with parenteral nutrition and 15 were starved routinely. There was some evidence that parenteral nutrition had a short-lived adverse effect on both the catheter sites and gastric emptying, but there were no marked adverse clinical effects and no evidence of any improvement in the horses' condition. 相似文献
998.
999.
1000.
OBJECTIVE: To investigate effects of intramammary infusion of beta-1,3-glucan or recombinant ovine interleukin-2 (rOvIL-2) on blood and mammary leukocyte subpopulations and their expression of various surface antigens in sheep. ANIMALS: 12 healthy multiparous, nonpregnant, nonlactating fine-wool Merino ewes. PROCEDURE: Beta-1,3-glucan in pyrogen-free saline solution (PFSS; n = 6), rOvIL-2 in PFSS (3), or PFSS (3) was infused on days 0 and 7 in 1 udder half of each ewe. Jugular vein blood and mammary secretion samples were taken before infusion and on days 2, 7, and 21 after infusion. Total and differential leukocyte counts were obtained, and blood and mammary cells were labeled for flow cytometry. RESULTS: Slight swelling of the mammary glands was observed on day 2 after rOvIL-2 but not after beta-1,3-glucan infusion. Both substances induced significant increase in mammary secretion leukocyte numbers, compared with controls. Beta-1,3-Glucan induced an influx of monocyte/macrophages, whereas neutrophils were the predominating cell population after rOvIL-2 infusion. Beta-1,3-glucan induced selection for CD4+, B-cell+, WC1+, and L-selectin+ lymphocytes on day 14 after infusion. By comparison, rOvIL-2 induced selection for B-cell+ and L-selectin+ lymphocytes on days 14 and 21 and depletion of CD8 and, to some degree, of IL-2R+ lymphocytes. Beta-1,3-Glucan induced an increase in the proportion of CD14+ leukocytes, indicating selective migration of monocyte/ macrophages to the nonlactating udder. CONCLUSION: Beta-1,3-Glucan and rOvIL-2 can modulate nonspecific immunity in the udder of sheep but may exert their effects by differing mechanisms. Clinical Relevance-Stimulation of the nonspecific defense against udder infections may improve control of mastitis. 相似文献