全文获取类型
收费全文 | 91898篇 |
免费 | 5717篇 |
国内免费 | 828篇 |
专业分类
林业 | 4230篇 |
农学 | 2908篇 |
基础科学 | 770篇 |
12106篇 | |
综合类 | 17122篇 |
农作物 | 3456篇 |
水产渔业 | 4412篇 |
畜牧兽医 | 46181篇 |
园艺 | 1406篇 |
植物保护 | 5852篇 |
出版年
2021年 | 947篇 |
2020年 | 1003篇 |
2019年 | 1122篇 |
2018年 | 1800篇 |
2017年 | 2016篇 |
2016年 | 1783篇 |
2015年 | 1666篇 |
2014年 | 1892篇 |
2013年 | 3473篇 |
2012年 | 3662篇 |
2011年 | 4176篇 |
2010年 | 2693篇 |
2009年 | 2503篇 |
2008年 | 3695篇 |
2007年 | 3554篇 |
2006年 | 3124篇 |
2005年 | 3058篇 |
2004年 | 2734篇 |
2003年 | 2752篇 |
2002年 | 2540篇 |
2001年 | 2698篇 |
2000年 | 2712篇 |
1999年 | 2120篇 |
1998年 | 850篇 |
1997年 | 763篇 |
1995年 | 791篇 |
1994年 | 700篇 |
1993年 | 700篇 |
1992年 | 1595篇 |
1991年 | 1772篇 |
1990年 | 1688篇 |
1989年 | 1630篇 |
1988年 | 1513篇 |
1987年 | 1565篇 |
1986年 | 1611篇 |
1985年 | 1436篇 |
1984年 | 1220篇 |
1983年 | 1036篇 |
1982年 | 692篇 |
1979年 | 1085篇 |
1978年 | 845篇 |
1976年 | 725篇 |
1975年 | 757篇 |
1974年 | 1024篇 |
1973年 | 1000篇 |
1972年 | 969篇 |
1971年 | 897篇 |
1970年 | 870篇 |
1969年 | 820篇 |
1967年 | 713篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
991.
992.
A.M. O'Connor J.M. Sargeant I.A. Gardner J.S. Dickson M.E. Torrence consensus meeting participants: C.E. Dewey I.R. Dohoo R.B. Evans J.T. Gray M. Greiner G. Keefe S.L. Lefebvre P.S. Morley A. Ramirez W. Sischo D.R. Smith K. Snedeker J. Sofos M.P. Ward R. Wills 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(1):57-64
The conduct of randomized controlled trials in livestock with production, health, and food-safety outcomes presents unique challenges that might not be adequately reported in trial reports. The objective of this project was to modify the CONSORT (Consolidated Standards of Reporting Trials) statement to reflect the unique aspects of reporting these livestock trials. A 2-day consensus meeting was held on November 18–19, 2008 in Chicago, IL, to achieve the objective. Before the meeting, a Web-based survey was conducted to identify issues for discussion. The 24 attendees were biostatisticians, epidemiologists, food-safety researchers, livestock production specialists, journal editors, assistant editors, and associate editors. Before the meeting, the attendees completed a Web-based survey indicating which CONSORT statement items would need to be modified to address unique issues for livestock trials. The consensus meeting resulted in the production of the REFLECT (Reporting Guidelines for Randomized Control Trials) statement for livestock and food safety and 22-item checklist. Fourteen items were modified from the CONSORT checklist, and an additional subitem was proposed to address challenge trials. The REFLECT statement proposes new terminology, more consistent with common usage in livestock production, to describe study subjects. Evidence was not always available to support modification to or inclusion of an item. The use of the REFLECT statement, which addresses issues unique to livestock trials, should improve the quality of reporting and design for trials reporting production, health, and food-safety outcomes. 相似文献
993.
994.
995.
Shirley Chu Sherry L. Myers Brent Wagner Elisabeth C.R. Snead 《The Canadian veterinary journal. La revue veterinaire canadienne》2013,54(8):743-747
Uncinaria stenocephala hookworm dermatitis (uncinariosis) was diagnosed on fecal examination and macerated skin biopsy in a 1.5-year-old greyhound dog from Saskatchewan. This is the first reported case in Canada. Treatment with moxidectin cleared gastrointestinal and dermal infections. 相似文献
996.
K. Matilainen E.A. Mäntysaari M.H. Lidauer I. Strandén R. Thompson 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2012,129(6):457-468
Multiple‐trait and random regression models have multiplied the number of equations needed for the estimation of variance components. To avoid inversion or decomposition of a large coefficient matrix, we propose estimation of variance components by Monte Carlo expectation maximization restricted maximum likelihood (MC EM REML) for multiple‐trait linear mixed models. Implementation is based on full‐model sampling for calculating the prediction error variances required for EM REML. Performance of the analytical and the MC EM REML algorithm was compared using a simulated and a field data set. For field data, results from both algorithms corresponded well even with one MC sample within an MC EM REML round. The magnitude of the standard errors of estimated prediction error variances depended on the formula used to calculate them and on the MC sample size within an MC EM REML round. Sampling variation in MC EM REML did not impair the convergence behaviour of the solutions compared with analytical EM REML analysis. A convergence criterion that takes into account the sampling variation was developed to monitor convergence for the MC EM REML algorithm. For the field data set, MC EM REML proved far superior to analytical EM REML both in computing time and in memory need. 相似文献
997.
998.
999.
Capece BP Castells G Pérez F Arboix M Cristòfol C 《Veterinary research communications》2000,24(5):339-348
Benzimidazole anthelmintic drugs are widely used in veterinary practice. Albendazole sulphoxide (ABZSO) is a benzimidazole drug with two enantiomers, as a consequence of a chiral centre in the sulphoxide group. The kinetics of these enantiomers were studied in male and female sheep. Plasma samples were obtained from the animals between 0.5 and 72 h after oral administration of 7.5 mg/kg of a racemic formulation of ABZSO (total-ABZSO). After a liquid–liquid extraction, the samples were analysed by HPLC to determine the concentrations of total-ABZSO and of the sulphone metabolite (ABZSO2). During the chromatographic analysis, the ABZSO peak was collected and reanalysed by an HPLC technique using a Chiral AGP column to quantify the enantiomeric proportion therein. After kinetic analysis, the AUCs obtained for the (+)-ABZSO were 5.8 and 4.0 times higher than those for the (–)-ABZSO in male and female animals, respectively. The mean residence times were 23.4 and 16.1 h for (+)-ABZSO and 22.2 and 17.4 h for (–)-ABZSO for male and female animals, respectively. The only significant difference between the sexes (p<0.05) was in the T
max of the (–)-ABZSO. Comparing both enantiomers within each sex, significant differences were found in all the kinetic parameters. Finally, no kinetic differences were found between sex for total-ABZSO or ABZSO2. 相似文献
1000.
Platt SR Helmick KE Graham J Bennett RA Phillips L Chrisman CL Ginn PE 《Journal of the American Veterinary Medical Association》1999,214(8):1218-20, 1200
Clinical, electromyographic, and pathologic findings characteristic of lead toxicosis were detected in a turkey vulture (Cathartes aura). The bird had generalized lower motor neuron dysfunction that progressed over 5 days. Electromyography revealed diffuse denervation potentials and a presumed decrement in the sciatic-tibial nerve conduction velocity. Histologic examination of peripheral nerves obtained at necropsy revealed changes that could be compatible with lead-induced neuropathy. Lead toxicosis was confirmed by determination of blood lead concentrations. Lead toxicosis causing neurologic disorders in birds has been described. However, this report emphasizes the effects of lead on the peripheral nervous system and demonstrates the use of electromyography for diagnosis of peripheral neuropathy in birds. 相似文献