全文获取类型
收费全文 | 721篇 |
免费 | 37篇 |
专业分类
林业 | 17篇 |
农学 | 27篇 |
基础科学 | 1篇 |
56篇 | |
综合类 | 80篇 |
农作物 | 36篇 |
水产渔业 | 47篇 |
畜牧兽医 | 447篇 |
园艺 | 9篇 |
植物保护 | 38篇 |
出版年
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2016年 | 12篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 24篇 |
2012年 | 23篇 |
2011年 | 29篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 26篇 |
2007年 | 23篇 |
2006年 | 34篇 |
2005年 | 37篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 34篇 |
2001年 | 24篇 |
2000年 | 30篇 |
1999年 | 24篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 20篇 |
1985年 | 16篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 9篇 |
1971年 | 4篇 |
1970年 | 7篇 |
1968年 | 4篇 |
1966年 | 5篇 |
1933年 | 3篇 |
排序方式: 共有758条查询结果,搜索用时 0 毫秒
91.
Sows were immunised subcutaneously with a live Salmonella cholerae suis (SCS) vaccine prior to farrowing. Serological tests demonstrated a high level of SCS colostral antibodies at parturition. Piglet sera negative for antibodies at birth contained a high level of SCS antibodies 24 h after the ingestion of vaccinated sow colostrum. Experiments were carried out to establish if these maternally derived antibodies could protect the piglets against an intranasal (IN) challenge with a field isolate of SCS. It was concluded that pregnant sows could be safely immunised with a live SCS vaccine thus providing their piglets with a passive immunity which protected them against an intranasal challenge. 相似文献
92.
A double blind controlled trial was carried out on four commercial dairy herds, to investigate the effect of one 50 mg injection of selenium, 10 days before parturition, on the incidence of weak calves. Although the treatment marginally increased the selenium status of treated calves it did not decrease the incidence of the weak calf syndrome. 相似文献
93.
94.
L E Perryman D R Leach W C Davis W D Mickelsen S R Heller H D Ochs J A Ellis E Brummerstedt 《Veterinary immunology and immunopathology》1989,21(3-4):239-248
Lymphocyte numbers and activities were evaluated at 2, 4, 8 and 12 weeks of age in two calves with lethal trait A46 (A46), a genetic disorder affecting intestinal zinc absorption. Plasma zinc concentrations declined to subnormal by 3 weeks of age, after which anorexia, diarrhea, alopecia and hyperkeratosis occurred. Lymphocyte response to phytohemagglutinin-P (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) stimulation was variably reduced. CD4+ T-lymphocytes were subnormal on at least one observation period following onset of zinc deficiency, and relative numbers of B lymphocytes were decreased at 8 weeks. Secondary antibody responses to bacteriophage phi X 174 were significantly reduced. The results demonstrate that calves homozygous for the A46 trait have normal numbers of functional lymphocyte subpopulations at birth, and that the activity of their lymphocytes is altered once the calves become zinc deficient. 相似文献
95.
96.
Antibody production in rainbow trout to extracellular antigens was investigated. The following antigen preparations and immunisation regimes were used: native extracellular products (ECP) in Freund's complete adjuvant (FCA), intraperitoneally (i.p.) with and without booster; formalinized ECP in FCA, i.p. with and without booster; washed, formalinized A. salmonicida cells in FCA, i.p., with booster; native ECP in saline, i.m., four weekly injections at two different doses, 45 micrograms and 6 micrograms each injection (after the protocol of Shieh, 1985). Using crossed normal rainbow trout serum, i.p., single injection (after the protocol of Sakai, 1985). Using crossed immunoelectrophoresis all antisera contained precipitating antibodies to three to five ECP components except that from fish immunised i.m. with 6 micrograms protein where antibodies were undetectable. In no case were specific antibodies to ECP protease or haemolysin detected. In a rabbit immunised with formalinized ECP in FCA under a similar regime to the rainbow trout, antibodies to at least 15 ECP components, including protease and haemolysin, were detected. The assumption of a specific immune response to the protease, at least in respect of antibody production, in recent reports of protection afforded by vaccines composed of either crude ECP or partially purified protease (Shieh, 1985) or partially purified protease inactivated by normal serum (Sakai, 1985) is not supported by the present findings. 相似文献
97.
98.
Coastal bermudagrass hay was labeled with Cr by the Cr-mordant procedure and with 177Lu applied to the same fiber. Neutral detergent fiber prepared from the same Coastal bermudagrass hay was labeled with Yb, 169Yb, Tb and 160Tb by soaking overnight following by thorough washing and drying. Wood chips were similarly labeled with Sm or La, and Solka Floc was labeled with 147Nd and 141Ce. The carriers, labels and times of administration to cattle were: bermudagrass fiber with both Cr and 177Lu, bermudagrass fiber with 169Yb and Solka Floc labeled with 147Nd at 0 h; bermudagrass fiber with Yb, Solka Floc with 141Ce and wood chips with Sm at 24 h; wood chips with La at 48 h; and bermudagrass fiber labeled with 160Tb at the beginning and labeled with Tb at the end of a meal. Fecal collection followed and passage characteristics were determined with a two-compartment, age-dependent model. Markers labeling the different fiber sources had different (P less than .01) passage rates (Solka Floc greater than Coastal bermudagrass greater than wood chips), but there was no difference within fiber source for rare earth passage. There also was no difference between the passage characteristics of Cr-mordant and 177Lu. However, passage rate of particles administered at the beginning of the meal (160Tb) was 42% higher than for particles at the end of the meal (Tb).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
99.
Leptospira interrogans serovar bratislava was recovered from 2 of 10 sows examined from an Iowa slaughterhouse. Isolations were made from the kidney and genital tract of each sow. Serovar bratislava is not included in vaccines because it has not been previously isolated in the United States. 相似文献
100.