全文获取类型
收费全文 | 30293篇 |
免费 | 1282篇 |
国内免费 | 8篇 |
专业分类
林业 | 1070篇 |
农学 | 892篇 |
基础科学 | 174篇 |
4561篇 | |
综合类 | 3980篇 |
农作物 | 1165篇 |
水产渔业 | 1146篇 |
畜牧兽医 | 16481篇 |
园艺 | 335篇 |
植物保护 | 1779篇 |
出版年
2021年 | 224篇 |
2020年 | 265篇 |
2019年 | 331篇 |
2018年 | 600篇 |
2017年 | 664篇 |
2016年 | 566篇 |
2015年 | 364篇 |
2014年 | 552篇 |
2013年 | 1662篇 |
2012年 | 863篇 |
2011年 | 1114篇 |
2010年 | 808篇 |
2009年 | 761篇 |
2008年 | 1077篇 |
2007年 | 1053篇 |
2006年 | 890篇 |
2005年 | 713篇 |
2004年 | 721篇 |
2003年 | 661篇 |
2002年 | 584篇 |
2001年 | 744篇 |
2000年 | 743篇 |
1999年 | 544篇 |
1998年 | 244篇 |
1997年 | 227篇 |
1995年 | 269篇 |
1992年 | 400篇 |
1991年 | 415篇 |
1990年 | 432篇 |
1989年 | 440篇 |
1988年 | 344篇 |
1987年 | 353篇 |
1986年 | 383篇 |
1985年 | 342篇 |
1984年 | 331篇 |
1983年 | 303篇 |
1979年 | 481篇 |
1978年 | 328篇 |
1977年 | 370篇 |
1976年 | 468篇 |
1975年 | 485篇 |
1974年 | 523篇 |
1973年 | 480篇 |
1972年 | 438篇 |
1971年 | 354篇 |
1970年 | 372篇 |
1969年 | 434篇 |
1968年 | 441篇 |
1967年 | 446篇 |
1966年 | 438篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
D J Dreyfuss J B Madison V B Reef 《Journal of the American Veterinary Medical Association》1990,197(12):1629-1630
A 6-year-old multiparous Holstein cow was admitted for evaluation of progressive milk flow obstruction of one quarter of the udder. Physical examination findings suggested the presence of a mural teat abscess. Ultrasonography substantiated the physical examination findings and delineated the extent of the lesion. Surgical excision of the abscess en bloc yielded satisfactory functional and cosmetic results. 相似文献
62.
全球禽肉生产和贸易中的沙门菌风险评估与控制 总被引:1,自引:0,他引:1
G.Mead A.M.Lammerding N.Cox M.P.Doyle F.Humbert A.Kulikocskiy A.Panin V.P.do Nascimento M.Wierup 《中国家禽》2011,33(5)
1 禽源沙门菌对公共卫生的影响
在许多国家,沙门菌仍是引发食源性肠道疾病的主要原因.沙门菌通常存在于家畜、家禽中,也可在啮齿类、爬行类和鸟类等野生动物中发现.当农场的禽群感染沙门菌后,通常会有一部分家禽的消化道中携带沙门菌,但并无症状.随后,沙门菌可能会通过粪便污染感染动物屠体. 相似文献
63.
编者按:在家禽养殖中,饲料是支撑家禽生长的最基本元素.除去营养需要外,高度加工处理的饲料从一开始着眼于提高家禽的生产性能,以达到效率最优化. 相似文献
64.
Verster RS Botha CJ Naidoo V Van Schalkwyk OL 《Journal of the South African Veterinary Association》2004,75(4):177-181
A survey of aldicarb poisoning in companion animals was conducted by posting questionnaires to all private practitioners in Gauteng Province, South Africa. The survey was designed to determine the percentage of aldicarb cases seen, treatment regimen, clinical signs observed, proposals for preventative actions and more effective treatments. Other questions included duration of treatment, survival rate, cost to clients, post mortem findings and reasons for poisonings. 相似文献
65.
Data from 1,909 purebred, F1, backcross and F2 and F3 inter se combinations of Angus and Hereford were used to estimate average individual, maternal and grandmaternal genetic effects, individual and maternal heterosis, dominance and epistatic genetic effects. Models for evaluating heterosis and epistatic or recombination effects were discussed. Average individual effects indicate that Angus, compared with Hereford, had calves that were born earlier, had lighter birth weights, lower pre- and postweaning gains and lower pregnancy rates. Angus also produced lighter weight carcasses with more fat cover and marbling. Maternal effects of Angus were in the direction of reduced birth weight, greater calving ease, higher preweaning but lower postweaning growth rate and increased fatness when contrasted with Hereford. There was a tendency for opposite direction of maternal and grandmaternal effects for traits influenced by preweaning maternal environment. When additive X additive effects were ignored, total heterosis was significant for earlier day born, heavier birth weight, preweaning and postweaning gain, and heavier and fatter carcasses. Heterosis retained in F3 inter se vs F1 generation crosses indicated that net epistatic effects were relatively negligible for date of calving, birth weight, weaning gain and fat cover. There was a greater reduction of heterosis effects than expected from dominance alone for survival, pregnancy and marbling score. Loss of heterosis in F3 was less than expected for postweaning gain, carcass weight and rib eye area. Except for survival, pregnancy and marbling, these deviations from dominance expectations, or lack of them, are favorable for F3 composite populations. 相似文献
66.
G. Sahoo T. More V.K. Singh 《Comparative immunology, microbiology and infectious diseases》1998,21(4):319-325
In the present study the level of enzyme hydrolases (alkaline phosphatase, myeloperoxidase, elastase, arginase, lysozyme and β-galactosidase) of polymorphonuclear cell (PMN) granules in different ruminant species and their release in response to activation was studied. Buffalo PMN alkaline phosphatase activity was higher (P < 0.01) than in PMNs of cattle and goats. Interestingly, myeloperoxidase was higher in cattle PMNs and least in goat PMNs (P < 0.01), a similar pattern was observed in the distribution of enzyme arginase. As far as lysozyme is concerned, its activity was significantly higher (P < 0.01) in PMNs of buffaloes than in the case of cattle and goat PMNs. On activation, these cells released MPO and elastase, in all the species studied, while lysozyme was secreted only in buffalo PMN cells. Activity of certain enzymes related to oxidant defence systems such as glutathione peroxidase and glutathione reductase were higher in cattle and goats compared to that in buffaloes. These observations are likely to have bearing on immunodefense roles played by PMNs and reflected differences among the ruminant species studied. 相似文献
67.
68.
69.
70.
Kumar V Madabushi R Lucchesi MB Derendorf H 《Journal of veterinary pharmacology and therapeutics》2011,34(2):130-135
Kumar, V., Madabushi, R., Lucchesi, M. B. B., Derendorf, H. Pharmacokinetics of cefpodoxime in plasma and subcutaneous fluid following oral administration of cefpodoxime proxetil in male beagle dogs. J. vet. Pharmacol. Therap. 34 , 130–135. Pharmacokinetics of cefpodoxime in plasma (total concentration) and subcutaneous fluid (free concentration using microdialysis) was investigated in dogs following single oral administration of prodrug cefpodoxime proxetil (equivalent to 5 and 10 mg/kg of cefpodoxime). In a cross over study design, six dogs per dose were utilized after a 1 week washout period. Plasma, microdialysate, and urine samples were collected upto 24 h and analyzed using high performance liquid chromatography. The average maximum concentration (Cmax) of cefpodoxime in plasma was 13.66 (±6.30) and 27.14 (±4.56) μg/mL with elimination half‐life (t1/2) of 3.01 (±0.49) and 4.72 (±1.46) h following 5 and 10 mg/kg dose, respectively. The respective average area under the curve (AUC0–∞) was 82.94 (±30.17) and 107.71 (±30.79) μg·h/mL. Cefpodoxime was readily distributed to skin and average free Cmax in subcutaneous fluid was 1.70 (±0.55) and 3.06 (±0.93) μg/mL at the two doses. Urinary excretion (unchanged cefpodoxime) was the major elimination route. Comparison of subcutaneous fluid concentrations using pharmacokinetic/pharmacodynamic indices of fT>MIC indicated that at 10 mg/kg dose; cefpodoxime would yield good therapeutic outcome in skin infections for bacteria with MIC50 upto 0.5 μg/mL while higher doses (or more frequent dosing) may be needed for bacteria with higher MICs. High urine concentrations suggested cefpodoxime use for urinary infections in dogs. 相似文献