全文获取类型
收费全文 | 81910篇 |
免费 | 5046篇 |
国内免费 | 770篇 |
专业分类
林业 | 3139篇 |
农学 | 2489篇 |
基础科学 | 674篇 |
9787篇 | |
综合类 | 16380篇 |
农作物 | 3020篇 |
水产渔业 | 3739篇 |
畜牧兽医 | 42466篇 |
园艺 | 1121篇 |
植物保护 | 4911篇 |
出版年
2021年 | 718篇 |
2020年 | 797篇 |
2019年 | 977篇 |
2018年 | 1346篇 |
2017年 | 1551篇 |
2016年 | 1377篇 |
2015年 | 1320篇 |
2014年 | 1495篇 |
2013年 | 2896篇 |
2012年 | 2854篇 |
2011年 | 3449篇 |
2010年 | 2277篇 |
2009年 | 2162篇 |
2008年 | 3070篇 |
2007年 | 2948篇 |
2006年 | 2653篇 |
2005年 | 2574篇 |
2004年 | 2297篇 |
2003年 | 2350篇 |
2002年 | 2201篇 |
2001年 | 2484篇 |
2000年 | 2528篇 |
1999年 | 1939篇 |
1998年 | 789篇 |
1997年 | 705篇 |
1995年 | 740篇 |
1993年 | 664篇 |
1992年 | 1526篇 |
1991年 | 1716篇 |
1990年 | 1640篇 |
1989年 | 1588篇 |
1988年 | 1472篇 |
1987年 | 1526篇 |
1986年 | 1572篇 |
1985年 | 1396篇 |
1984年 | 1187篇 |
1983年 | 1015篇 |
1982年 | 679篇 |
1979年 | 1055篇 |
1978年 | 829篇 |
1977年 | 672篇 |
1976年 | 711篇 |
1975年 | 746篇 |
1974年 | 1003篇 |
1973年 | 984篇 |
1972年 | 951篇 |
1971年 | 878篇 |
1970年 | 851篇 |
1969年 | 804篇 |
1967年 | 701篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Parelaphostrongylus tenuis Cerebrospinal Nematodiasis in a Horse with Cervical Scoliosis and Meningomyelitis 下载免费PDF全文
N.S. Mittelman T.J. Divers J.B. Engiles R. Gerhold S. Ness P.V. Scrivani T. Southard A.L. Johnson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2017,31(3):890-893
There are reports of horses with acute onset acquired cervical scoliosis and cutaneous analgesia. The underlying dorsal gray column myelitis that produces these neurologic signs has been only presumptively attributed to migration of Parelaphostrongylus tenuis within the spinal cord. Despite previous confirmation brain by polymerase chain reaction testing, of P. tenuis within the brain of horses by polymerase chain reaction testing, genetic testing has failed to definitively identify the presence of this parasite in cases of equine myelitis. This case report provides molecular confirmation via polymerase chain reaction of P. tenuis within the cervical spinal cord of a horse with scoliosis and cutaneous analgesia. 相似文献
994.
Pharmacokinetics and dynamics of mycophenolate mofetil after single‐dose oral administration in juvenile dachshunds 下载免费PDF全文
M. Grobman D. M. Boothe H. Rindt B. G. Williamson M. L. Katz J. R. Coates C. R. Reinero 《Journal of veterinary pharmacology and therapeutics》2017,40(6):e1-e10
Mycophenolate mofetil (MMF) is recommended as an alternative/complementary immunosuppressant. Pharmacokinetic and dynamic effects of MMF are unknown in young‐aged dogs. We investigated the pharmacokinetics and pharmacodynamics of single oral dose MMF metabolite, mycophenolic acid (MPA), in healthy juvenile dogs purpose‐bred for the tripeptidyl peptidase 1 gene (TPP1) mutation. The dogs were heterozygous for the mutation (nonaffected carriers). Six dogs received 13 mg/kg oral MMF and two placebo. Pharmacokinetic parameters derived from plasma MPA were evaluated. Whole‐blood mitogen‐stimulated T‐cell proliferation was determined using a flow cytometric assay. Plasma MPA Cmax (mean ± SD, 9.33 ± 7.04 μg/ml) occurred at <1 hr. The AUC0–∞ (mean ± SD, 12.84±6.62 hr*μg/ml), MRTinf (mean ± SD, 11.09 ± 9.63 min), T1/2 (harmonic mean ± PseudoSD 5.50 ± 3.80 min), and k/d (mean ± SD, 0.002 ± 0.001 1/min). Significant differences could not be detected between % inhibition of proliferating CD5+ T lymphocytes at any time point (p = .380). No relationship was observed between MPA concentration and % inhibition of proliferating CD5+ T lymphocytes (R = .148, p = .324). Pharmacodynamics do not support the use of MMF in juvenile dogs at the administered dose based on existing therapeutic targets. 相似文献
995.
996.
E. Treggiari L. Ressel G. A. Polton J. Benoit I. Desmas L. Blackwood 《Veterinary and comparative oncology》2017,15(1):i-i
The cover image, by E. Treggiari et al., is based on the Original Article Clinical outcome, PDGFRß and KIT expression in feline histiocytic disorders: a multicentre study, DOI: 10.1111/vco.12142 .
997.
Indicators of success for smart law enforcement in protected areas: A case study for Russian Amur tiger (Panthera tigris altaica) reserves 下载免费PDF全文
Michiel H. H. HÖTTE Igor A. KOLODIN Sergei L. BEREZNUK Jonathan C. SLAGHT Linda L. KERLEY Svetlana V. SOUTYRINA Galina P. SALKINA Olga Y. ZAUMYSLOVA Emma J. STOKES Dale G. MIQUELLE 《Integrative zoology》2016,11(1):2-15
Although considerable conservation resources have been committed to develop and use law enforcement monitoring and management tools such as SMART, measures of success are ill‐defined and, to date, few reports detail results post‐implementation. Here, we present 4 case studies from protected areas with Amur tigers (Panthera tigris altaica) in Russia, in which indicators of success were defined and evaluated at each. The ultimate goal was an increase in tiger numbers to 1 individual/100 km2 at each site. We predicted that improvements in law enforcement effectiveness would be followed by increases in prey numbers and, subsequently, tiger numbers. We used short‐term and long‐term indicators of success, including: (i) patrol team effort and effectiveness; (ii) catch per unit effort indicators (to measure reductions in threats); and (iii) changes in target species numbers. In addition to implementing a monitoring system, we focused on improving law enforcement management using an adaptive management process. Over 4 years, we noted clear increases in patrol effort and a partial reduction in threats. Although we did not detect clear trends in ungulate numbers, tiger populations remained stable or increased, suggesting that poaching of tigers may be more limiting than prey depletion. Increased effectiveness is needed before a clear reduction in threats can be noted, and more time is needed before detecting responses in target populations. Nonetheless, delineation of concrete goals and indicators of success provide a means of evaluating progress and weaknesses. Such monitoring should be a central component of law enforcement strategies for protected areas. 相似文献
998.
999.
1000.