全文获取类型
收费全文 | 30628篇 |
免费 | 1299篇 |
国内免费 | 8篇 |
专业分类
林业 | 1079篇 |
农学 | 895篇 |
基础科学 | 175篇 |
4576篇 | |
综合类 | 4017篇 |
农作物 | 1169篇 |
水产渔业 | 1173篇 |
畜牧兽医 | 16725篇 |
园艺 | 338篇 |
植物保护 | 1788篇 |
出版年
2021年 | 226篇 |
2020年 | 266篇 |
2019年 | 333篇 |
2018年 | 605篇 |
2017年 | 664篇 |
2016年 | 567篇 |
2015年 | 364篇 |
2014年 | 553篇 |
2013年 | 1684篇 |
2012年 | 866篇 |
2011年 | 1123篇 |
2010年 | 815篇 |
2009年 | 765篇 |
2008年 | 1086篇 |
2007年 | 1067篇 |
2006年 | 898篇 |
2005年 | 721篇 |
2004年 | 736篇 |
2003年 | 672篇 |
2002年 | 598篇 |
2001年 | 757篇 |
2000年 | 749篇 |
1999年 | 565篇 |
1998年 | 245篇 |
1997年 | 235篇 |
1995年 | 273篇 |
1992年 | 410篇 |
1991年 | 424篇 |
1990年 | 438篇 |
1989年 | 451篇 |
1988年 | 354篇 |
1987年 | 359篇 |
1986年 | 392篇 |
1985年 | 346篇 |
1984年 | 338篇 |
1983年 | 309篇 |
1979年 | 488篇 |
1978年 | 330篇 |
1977年 | 372篇 |
1976年 | 469篇 |
1975年 | 488篇 |
1974年 | 526篇 |
1973年 | 483篇 |
1972年 | 442篇 |
1971年 | 359篇 |
1970年 | 375篇 |
1969年 | 441篇 |
1968年 | 442篇 |
1967年 | 450篇 |
1966年 | 439篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Dabrin A. Bégorre C. Bretier M. Dugué V. Masson M. Le Bescond C. Le Coz J. Coquery M. 《Journal of Soils and Sediments》2021,21(2):1256-1274
Journal of Soils and Sediments - Suspended particulate matter (SPM) transport through rivers is a major vector of nutrients and pollutants to continental shelf areas. To develop efficient sediment... 相似文献
992.
Spyrou V Papanastassopoulou M Psychas V Billinis Ch Koumbati M Vlemmas J Koptopoulos G 《Veterinary microbiology》2003,95(1-2):49-59
There appears to be a lack of information concerning responses of mules to natural infection or experimental inoculation with equine infectious anemia virus (EIAV). In the present study EIAV was isolated from mules, for the first time, and its pathogenicity in naturally infected and experimentally inoculated animals was investigated. Two naturally infected (A and B) and three EIAV free mules (C, D and E) were used for this purpose. Mule A developed clinical signs, whereas mule B remained asymptomatic until the end of the study. Mules C and D were each inoculated with 10ml of blood from mule A and developed signs of the disease; they were euthanatized or died at day 22 and 25 post-inoculation, respectively. Mule E served as a negative control. The virus was isolated from the plasma samples of mules with clinical signs of the disease (A, C and D), but not from the asymptomatic mule B. Both proviral DNA and viral RNA were amplified from blood and tissues of the infected animals by nested polymerase chain reaction (nPCR). Antibodies were not detected in the two experimentally infected mules until their natural death or euthanasia. Clinicopathological and laboratory findings showed that, in mules, EIAV produced clinical signs similar to those observed in horses and ponies. Nested PCR proved to be a rapid, sensitive and specific diagnostic method for the detection of EIAV, regardless of the disease stage. 相似文献
993.
Bailiff NL Norris CR Seguin B Griffey SM Ling GV 《Journal of the American Animal Hospital Association》2004,40(1):69-74
Pancreatolithiasis has been documented to occur naturally in humans and cattle. It has been associated with chronic pancreatitis in humans, and, when found, it may signify the presence of chronic pancreatic disease. This is the first report of a case involving a cat that had both an apparent obstruction with pancreatolithiasis as well as concurrent evidence of chronic pancreatic changes on histopathological evaluation. Additionally, this case documents the presence of a suspected congenital abnormality of a feline exocrine pancreas. 相似文献
994.
995.
996.
997.
S. Gilbert V. K. Affolter P. Schmidt S. Kosten P. M. Kramme T. L. Gross P. Ihrke P. F. Moore 《Veterinary dermatology》2004,15(Z1):24-24
A previous study described cutaneous lymphocytosis (CL) in 23 cats. The process resembles cutaneous pseudolymphoma in humans, a heterogeneous group of benign reactive proliferations of well‐differentiated lymphocytes in the skin of humans. Morphological and immunophenotypic characteristics do not offer reliable criteria to accurately predict the clinical outcome of feline CL or pseudolymphoma in humans. Presence of clonal cell populations is more consistent with a neoplastic process. In a previous study, feline CL lesions (20 cats) were evaluated for clonality using PCR, and only two cats had monoclonal T‐cell populations. Because false‐negative results may occur, the purpose of this study was to repeat the PCR using a revised primer set based on analysis of additional feline T‐cell receptor γ (TCRγ) sequences. DNA was isolated from 29 skin lesions and six internal organs of 20 cats. DNA integrity was assessed by glyceraldehyde‐3‐phosphate dehydrogenase PCR. Polymerase chain reaction clonality was performed using the revised primer set specific for feline TCRγ, and duplicate samples were evaluated. The PCR products were assessed by heteroduplex analysis. Clonal rearrangement of TCRγ was detected in 14 cats (24 of 35 tissues: 21 of 29 skin lesions and three of six internal organs); eight of these cats are still alive and six were euthanized. Monoclonal populations were seen in three of five cats that had involvement of internal organs. These findings indicate that feline CL is best considered as a slowly progressive process which may be reactive, but often evolves into a low‐grade indolent lymphoma. Funding: George H. Muller Fund for Research in Dermatology. 相似文献
998.
To estimate the prevalence of enteric parasites and selected vector-borne agents of dogs and cats in San Isidro de El General, Costa Rica, fecal and serum samples were collected from animals voluntarily undergoing sterilization. Each fecal sample was examined for parasites by microscopic examination after fecal flotation and for Giardia and Cryptosporidium using an immunofluorescence assay (IFA). Giardia and Cryptosporidium IFA positive samples were genotyped after PCR amplification of specific DNA if possible. The seroprevalence rates for the vector-borne agents (Dirofilaria immitis, Borrelia burgdorferi, Ehrlichia canis, and Anaplasma phagocytophilum) were estimated based on results from a commercially available ELISA. Enteric parasites were detected in samples from 75% of the dogs; Ancylostoma caninum, Trichuris vulpis, Giardia, and Toxocara canis were detected. Of the cats, 67.5% harbored Giardia spp., Cryptosporidium spp., Ancylostoma tubaeforme, or Toxocara cati. Both Cryptosporidium spp. isolates that could be sequenced were Cryptosporidium parvum (one dog isolate and one cat isolate). Of the Giardia spp. isolates that were successfully sequenced, the 2 cat isolates were assemblage A and the 2 dog isolates were assemblage D. D. immitis antigen and E. canis antibodies were identified in 2.3% and 3.5% of the serum samples, respectively. The prevalence of enteric zoonotic parasites in San Isidro de El General in Costa Rica is high in companion animals and this information should be used to mitigate public health risks. 相似文献
999.
Anthelmintics for the control of nematode infections in the brushtail possum (Trichosurus vulpecula)
AIMS: To determine the efficacy of eprinomectin, doramectin and a combination of albendazole and levamisole in suppressing or eliminating nematode infections or faecal egg counts (FEC) in possums naturally or experimentally infected with Parastrongyloides trichosuri, Paraustrostrongylus trichosuri and Trichostrongylus colubriformis. METHODS: To establish an effective dose of eprinomectin, groups of naturally infected possums were treated with 0, 0.5, 2.5, 5.0 or 7.5 mg/kg liveweight (LW) eprinomectin pour-on (n=6 possums/group) and changes in FEC and nematode worm counts at necropsy determined, 18 days later. Efficacy of the 7.5 mg/kg dose was re-examined in a second group of naturally infected possums (n=12) by monitoring FEC weekly for 28 days post-treatment. Persistence of the anthelmintic effect of doramectin injection was tested using nematode-free possums treated with 0, 0.2, 0.4, 0.6 or 0.8 mg/kg LW (n=3 possums/ group), which were experimentally infected 14 days later with T. colubriformis, Paraustrostrongylus trichosuri and Parastrongyloides trichosuri infective larvae. Response to treatment was assessed by FEC and nematode worm counts at necropsy, 42 days posttreatment. Efficacy of a 1.0 mg/kg dose of doramectin was subsequently examined using naturally infected possums (n=11) by monitoring FEC weekly for 28 days post-treatment. To determine the efficacy of a levamisole-albendazole combination drench, possums with naturally acquired nematode infections (n=6) were treated orally with 37.5 mg/kg LW levamisole plus 23.75 mg/kg LW albendazole on 2 occasions, 7 days apart, and response to treatment was assessed by monitoring FEC for 57 days. RESULTS: Eprinomectin 7.5 mg/kg LW reduced Paraustrostrongylus trichosuri worm counts by 98 % (p<0.05). Doramectin 0.6 mg/kg LW reduced Parastrongyloides trichosuri and Trichostrongylus spp worm counts by 99% (p<0.05) and 0.8 mg/kg LW reduced Paraustrostrongylus trichosuri by 100% (p<0.05), in possums challenged with larvae 14 days after treatment. Treating possums with a levamisole-albendazole combination orally, twice, 7-days apart, reduced FEC by 99%. CONCLUSIONS: The doses of anthelmintics required to effectively control nematodes in possums were higher than those recommended for animals for which they are currently registered. Possums tolerate the high dose rates of anthelmintics used in this study without apparent adverse effects. 相似文献
1000.