全文获取类型
收费全文 | 1436篇 |
免费 | 55篇 |
专业分类
林业 | 74篇 |
农学 | 36篇 |
基础科学 | 14篇 |
128篇 | |
综合类 | 242篇 |
农作物 | 92篇 |
水产渔业 | 59篇 |
畜牧兽医 | 731篇 |
园艺 | 12篇 |
植物保护 | 103篇 |
出版年
2021年 | 17篇 |
2020年 | 20篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 23篇 |
2014年 | 19篇 |
2013年 | 64篇 |
2012年 | 48篇 |
2011年 | 53篇 |
2010年 | 49篇 |
2009年 | 27篇 |
2008年 | 52篇 |
2007年 | 46篇 |
2006年 | 47篇 |
2005年 | 57篇 |
2004年 | 54篇 |
2003年 | 47篇 |
2002年 | 35篇 |
2001年 | 34篇 |
2000年 | 38篇 |
1999年 | 26篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 17篇 |
1995年 | 20篇 |
1994年 | 12篇 |
1992年 | 22篇 |
1991年 | 24篇 |
1990年 | 24篇 |
1989年 | 27篇 |
1988年 | 20篇 |
1987年 | 17篇 |
1986年 | 22篇 |
1985年 | 25篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1979年 | 14篇 |
1977年 | 16篇 |
1976年 | 18篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1973年 | 23篇 |
1972年 | 20篇 |
1971年 | 15篇 |
1948年 | 12篇 |
1947年 | 13篇 |
排序方式: 共有1491条查询结果,搜索用时 0 毫秒
981.
Neuroaxonal dystrophy in a rottweiler pup 总被引:1,自引:0,他引:1
M G Evans T P Mullaney C T Lowrie 《Journal of the American Veterinary Medical Association》1988,192(11):1560-1562
An 8-month-old Rottweiler pup was evaluated for neurologic disorder. Clinical signs included ataxia, hypermetria of all 4 limbs, intention tremors of the head, lack of a menace reflex bilaterally, and mild proprioceptive deficits. The pup was euthanatized because of the progressive nature of the disease. Histopathologic findings consisted of decreased numbers of Purkinje cells in the cerebellum and moderate numbers of axonal spheroids in the nucleus cuneatus. This latter finding confirmed the diagnosis of neuroaxonal dystrophy. 相似文献
982.
Plasma lactate measurements in healthy beagle dogs 总被引:1,自引:0,他引:1
G O Evans 《American journal of veterinary research》1987,48(1):131-132
Plasma lactate concentrations were determined in venous blood samples collected from 60 healthy Beagles aged 5 to 9 months. The range of values (0.42 to 3.58 mmol/L) obtained with an enzymatic method in the present study was similar to values reported in smaller studies with the colorimetric procedures. 相似文献
983.
J A Hawkins R R Evans C E Taylor C E Couvillion E F Illyes C P Wilkins M H Johnson-Delivorias T D Tyler 《American journal of veterinary research》1987,48(5):848-851
From Nov 22, 1983 through May 15, 1984, 36 crossbred steers were allotted into 3 treatment groups (12/group) and were grazed on separate 3.4-hectare pastures. On Nov 22, 1983, the steers were administered a single morantel sustained-release bolus (MSRB), orally (group 1), or a single dose of thiabendazole (TBZ; 66 mg/kg of body weight, orally; group 2), or were left untreated (group 3; controls). Animal weights, nematode egg counts in fecal specimens, and plasma pepsinogen concentrations were monitored monthly. At the termination of the study, 4 steers from each treatment group were slaughtered and necropsied and worm counts were determined. A set of parasite-free tracer calves (3/treatment group) were grazed with each treatment group for 1 month, beginning on Nov 22, 1983; a second set of tracer calves (3/group) were grazed with each treatment group for 1 month, beginning Apr 3, 1984. At the end of their respective grazing periods, tracer calves were held for 3 weeks and then were slaughtered and necropsied and their worm counts were determined. Mean nematode egg counts in fecal specimens of group 1 (MSRB treated) were significantly lower (P less than 0.05) than that of the TBZ-treated or nontreated steers. Differences in worm counts were not found between treatment groups. Differences in worm counts of tracer calves were not found among the 3 groups for November 1983 nor for April 1984. Steers treated with the MSRB had a higher mean weight gain (P less than 0.06) than did the control or TBZ-treated steers. 相似文献
984.
Rostral mandibulectomy in five horses. 总被引:1,自引:0,他引:1
D W Richardson L H Evans E P Tulleners 《Journal of the American Veterinary Medical Association》1991,199(9):1179-1182
Rostral mandibulectomy with primary gingival closure was performed in 5 horses with rapidly growing or bleeding mandibular tumors. The technique involved preservation of the most caudal portion of the mandibular symphysis to maintain stability. There were no surgical complications or recurrences, and the cosmetic and functional results were good. The histopathologic diagnosis of all the tumors was ossifying fibroma. Rostral mandibulectomy affords a simple and effective technique of treating tumors of the rostral portion of the mandible in horses. 相似文献
985.
The uptake by roots from solution, and subsequent translocation to shoots in barley, of two series of non-ionised chemicals, O-methylcarbamoyloximes and substituted phenylureas, were measured, Uptake of the chemicals by roots was greater the more lipophilic the chemical, and fell to a lower limiting value for polar chemicals. Translocation to the shoots was a passive process, and was most efficient for compounds of intermediate polarity. Both processes had reached equilibrium within 24h of treatment. The reported behaviour of many pesticides in various plant species agrees with the derived relationships, but the detailed mechanisms of these processes are unknown. 相似文献
986.
987.
A J Evans D W Bannister C C Whitehead W G Siller P A Wight 《Research in veterinary science》1977,23(3):275-279
Plasma glucose, free fatty acid and triglyceride levels were measured during the onset of fatty liver and kidney syndrome in chicks. Intial studies indicated that behavioural and clinical changes characteristically associated with the syndrome were observed only during the 24 h preceding death. A more detailed examination of the blood changes was made on fasted birds. Typically, affected birds could be distinguished from healthy fasted birds by a hypoglycaemia which developed within 2.5 h of the removal of food, and a slightly higher and more sustained elevation of free fatty acid levels. Triglyceride values were not generally different from those found in normal birds. Although moderate to large amounts of lipid were occasionally observed in the kidneys of healthy fasted birds, only in affected birds was significant lipid infiltration of the kidneys associated with a similar level of lipid infiltration of the liver. In extreme cases death from fatty liver and kidney syndrome could occur within 4 h of the removal of food. 相似文献
988.
J E Evans W Zontine E Grain 《Journal of the American Veterinary Medical Association》1985,186(1):78-80
Atypical prostatic adenocarcinoma was diagnosed in a castrated dog. The gland was of normal size, contrary to what has been reported in most other cases in dogs. Metastases were not seen, even though radiography suggested metastasis to the external iliac lymph nodes and histologic examination revealed the neoplasm to have a moderately malignant character. Even though hormones have been implicated as a cause of prostatic adenocarcinoma in man, the development of such a neoplasm in dogs castrated at an early age, as exemplified by this case, may cast doubt on that hypothesis. 相似文献
989.
990.
Electroejaculation and artificial insemination in Vietnamese potbellied miniature pigs 总被引:1,自引:0,他引:1
A 15-month-old Vietnamese miniature boar was examined because of suspected infertility. A breeding soundness examination was conducted, using electroejaculation under anesthesia for semen collection. Semen values were normal despite a subpubic location of the testes. Artificial insemination of a gilt with extended semen resulted in the birth of a litter 111 days later. Vietnamese potbellied boars have small and sometimes nearly undetectable scrotal pouches, which may cause the producer to question the fertility of the boars. 相似文献