全文获取类型
收费全文 | 81463篇 |
免费 | 4359篇 |
国内免费 | 96篇 |
专业分类
林业 | 3358篇 |
农学 | 2121篇 |
基础科学 | 479篇 |
9069篇 | |
综合类 | 15796篇 |
农作物 | 3265篇 |
水产渔业 | 3666篇 |
畜牧兽医 | 42639篇 |
园艺 | 925篇 |
植物保护 | 4600篇 |
出版年
2019年 | 773篇 |
2018年 | 1148篇 |
2017年 | 1265篇 |
2016年 | 1117篇 |
2015年 | 943篇 |
2014年 | 1261篇 |
2013年 | 2722篇 |
2012年 | 2234篇 |
2011年 | 2763篇 |
2010年 | 1710篇 |
2009年 | 1806篇 |
2008年 | 2738篇 |
2007年 | 2563篇 |
2006年 | 2458篇 |
2005年 | 2278篇 |
2004年 | 2228篇 |
2003年 | 2282篇 |
2002年 | 2066篇 |
2001年 | 2415篇 |
2000年 | 2469篇 |
1999年 | 1898篇 |
1998年 | 757篇 |
1997年 | 746篇 |
1996年 | 742篇 |
1995年 | 834篇 |
1993年 | 761篇 |
1992年 | 1580篇 |
1991年 | 1771篇 |
1990年 | 1654篇 |
1989年 | 1667篇 |
1988年 | 1485篇 |
1987年 | 1552篇 |
1986年 | 1608篇 |
1985年 | 1566篇 |
1984年 | 1199篇 |
1983年 | 1078篇 |
1982年 | 716篇 |
1979年 | 1157篇 |
1978年 | 910篇 |
1977年 | 765篇 |
1975年 | 787篇 |
1974年 | 1039篇 |
1973年 | 1030篇 |
1972年 | 1046篇 |
1971年 | 995篇 |
1970年 | 990篇 |
1969年 | 906篇 |
1968年 | 813篇 |
1967年 | 807篇 |
1966年 | 739篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
972.
973.
974.
975.
976.
977.
A Field Trial of a Pilated Moraxella bovis Bacterin for the Prevention of Infectious Bovine Keratoconjunctivitis 下载免费PDF全文
Bateman KG Leslie KE Scholl TP 《The Canadian veterinary journal. La revue veterinaire canadienne》1986,27(1):23-27
Two field trials were conducted to evaluate the efficacy of a Moraxella bovis bacterin in the control of infectious bovine keratoconjunctivitis. The bacterin did not affect the incidence of infectious bovine keratoconjunctivitis in either trial but did appear to reduce the severity of lesions, treatments required and withdrawals from pasture required in one trial. Possible reasons for the apparently contradictory results are offered. It is suggested that the bacterin may be of some value when used in conjunction with other preventive measures. 相似文献
978.
D W Vogt M R Ellersieck W E Deutsch B Akremi M N Islam 《American journal of veterinary research》1986,47(1):188-191
Fourteen instances of meningocele-encephalocele in an experimental herd were recorded over a 5-year period. Thirteen of these affected animals were subjected to extensive pedigree analyses. Familial associations were strong, and clearly the meningocele-encephalocele in this herd was under genetic influence. However, additional studies are needed to clarify the mode of inheritance and, perhaps, to identify other factors that might be involved. 相似文献
979.
Poxvirus infections are common in domestic birds in Germany, but they are rare in birds of prey. Only species of falconidae imported from Arabian or Asian countries have so far tested positive for poxvirus, and, among these, only raptors kept for falconry. As part of a reintroduction programme in the northern county of Mecklenburg-Western Pomerania, which is adjacent to the Baltic Sea, 21 young peregrine falcons were released into the wild; six of them died and one was examined postmortem, its tissues being examined by light and electron microscopy. In addition, an ELISA for fowlpox, pigeonpox and canarypox was applied. No virus could be isolated and propagation in culture failed, but virus particles were detected by electron microscopy in lesions from its skin and tongue. 相似文献
980.
Burkholder WJ Lees GE LeBlanc AK Slater MR Bauer JE Kashtan CE McCracken BA Hannah SS 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2004,18(2):165-175
Young adult heterozygous (carrier) female dogs with X-linked hereditary nephropathy (XLHN) have glomerular proteinuria but are otherwise healthy. Because data regarding dietary influences on the magnitude of proteinuria in dogs with spontaneous glomerular disease are not available, 12 such dogs were studied in a double crossover experiment intended to determine effects of altering dietary protein intake for up to 6 weeks. Dogs were blocked by urine protein : creatinine ratio (UPC) and randomly assigned to receive 2 diets: high protein (34.6% dry matter [DM], HP) or low protein (14.1% DM, LP) fed in HP-LP-HP or LP-HP-LP sequence. Food intake was measured daily, body weight (BW) was measured twice weekly, and UPC, plasma creatinine, blood urea nitrogen, phosphorus, albumin, and protein concentrations were measured at 2-week intervals. Nutrient digestibility was measured during the third treatment period. Diet had a significant effect (P < .0001) on all measured variables except plasma phosphorus (P > .5), but unintended differences in digestibility of protein and energy (P < or = .01) prevented assignment of the diet effect exclusively to protein. Proteinuria was greater (UPC 4.7 +/- 2.2 versus 1.8 +/- 1.1, P < .0001) when the HP diet was fed, but the LP diet did not maintain starting BW or plasma albumin concentration within the normal reference range. Diet greatly affects the magnitude of proteinuria in XLHN carrier females. Dietary protein restriction can reduce proteinuria in dogs with glomerular disease, but BW and blood protein concentrations may not be maintained if the restriction is too severe. 相似文献