全文获取类型
收费全文 | 16867篇 |
免费 | 3833篇 |
国内免费 | 111篇 |
专业分类
林业 | 1177篇 |
农学 | 875篇 |
基础科学 | 95篇 |
4097篇 | |
综合类 | 478篇 |
农作物 | 688篇 |
水产渔业 | 3321篇 |
畜牧兽医 | 7739篇 |
园艺 | 203篇 |
植物保护 | 2138篇 |
出版年
2023年 | 88篇 |
2022年 | 152篇 |
2021年 | 405篇 |
2020年 | 737篇 |
2019年 | 1230篇 |
2018年 | 1298篇 |
2017年 | 1349篇 |
2016年 | 1334篇 |
2015年 | 1117篇 |
2014年 | 1185篇 |
2013年 | 1587篇 |
2012年 | 1296篇 |
2011年 | 1239篇 |
2010年 | 1054篇 |
2009年 | 658篇 |
2008年 | 823篇 |
2007年 | 685篇 |
2006年 | 607篇 |
2005年 | 585篇 |
2004年 | 512篇 |
2003年 | 480篇 |
2002年 | 411篇 |
2001年 | 293篇 |
2000年 | 324篇 |
1999年 | 208篇 |
1998年 | 52篇 |
1997年 | 67篇 |
1996年 | 42篇 |
1995年 | 39篇 |
1994年 | 27篇 |
1993年 | 28篇 |
1992年 | 60篇 |
1991年 | 46篇 |
1990年 | 55篇 |
1989年 | 54篇 |
1988年 | 42篇 |
1987年 | 43篇 |
1986年 | 51篇 |
1985年 | 54篇 |
1984年 | 41篇 |
1983年 | 37篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1979年 | 35篇 |
1978年 | 37篇 |
1977年 | 33篇 |
1974年 | 28篇 |
1973年 | 46篇 |
1972年 | 32篇 |
1971年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Valeria F. Del Coco María Alejandra Córdoba Gladys Bilbao Pinto de Almeida Castro Juan Angel Basualdo Mónica Santín 《Veterinary parasitology》2014,199(1-2):112-115
Fecal specimens were obtained from a total of 70 dairy calves less than two months old on 11 municipalities in Buenos Aires, Argentina. After removal of fecal debris by sieving and sucrose flotation, specimens were subjected to PCR to detect the presence of Enterocytozoon bieneusi. PCR revealed a 14.3% of prevalence for E. bieneusi with 10 positive calves from 7 municipalities. Gene sequence analysis conducted in all samples positives by PCR revealed the presence of six genotypes; four previously reported in cattle as well as humans (D, I, J, and BEB4), one never reported in cattle before but previously reported in humans (EbpC), and one novel genotype (BEB10). These results constitute the first molecular characterization of E. bieneusi in Argentina, and suggest a potential risk of zoonotic transmission in this area. 相似文献
962.
963.
964.
A.‐H. K. Osman S. M. Farouk H. Eidaroos L. C. Abbott A. A. Ahmed 《Anatomia, histologia, embryologia》2014,43(2):141-152
The present investigation examined histogenesis of epithelial, stromal and angiogenic elements of the prenatal camel permanent or metanephric kidney. The primitive metanephros was first observed at the 13‐mm crown vertebral rump length (CVRL) stage as an ovoid structure composed of a centrally located epithelial ureteric bud and peripheral circumscribed masses of undifferentiated mesenchymal cells. The first morphological evidence of glomerulogenesis was observed at the 28‐mm CVRL stage. Developing renal corpuscles became obvious at the 35‐mm CVRL stage. At the 60‐mm CVRL stage, the epithelial renal pelvis gave rise to tubular branches that extended towards the cortical zone. These branches represented the presumptive collecting ducts. Differentiation of renal tubules into the proximal and distal convoluted tubules was observed at the 95‐mm CVRL stage. At the 130‐mm CVRL stage, the renal medulla was clearly delineated into medullary pyramids, which in association with the corresponding cortical caps formed the morphological basis of the renal lobar formation. A gradual nephrogenic decline was noticed from the 940‐mm CVRL on; however, the process of nephrogenesis persisted throughout all the studied foetal stages. 相似文献
965.
Jessica Maria Leite dos Santos Jomar Patrício Monteiro Wesley Lyeverton Correia Ribeiro Iara Tersia Freitas Macedo Ana Lourdes Fernandes Camurça-Vasconcelos Luiz da Silva Vieira Claudia Maria Leal Bevilaqua 《Veterinary parasitology》2014,199(3-4):160-164
Haemonchus contortus is the most prevalent nematode in Brazil. The objective of this study was to select 6 populations of H. contortus of known or suspected benzimidazole resistance status and characterize these using quantitative real-time polymerase chain reaction (qPCR) for single nucleotide polymorphisms (SNPs) F200Y, F167Y and E198A in the β-tubulin isotype 1 gene. qPCR was performed using DNA from a pool of 10 adult male H. contortus from a single animal per farm. Faecal egg count reduction test (FECRT) and egg hatch test (EHT) were used to determine the resistance status. Samples were obtained from 6 farms located in 5 counties in the Ceará State: Tauá, Boa Viagem, Quixadá, Santa Quitéria and Solonópole. The inbred-susceptible-Edinburgh (ISE) isolate was used as reference for comparative purposes in the qPCR. Benzimidazole resistance was detected by FECRT on all farms with efficacy values ranging from 0 to 51%. EC50 values as determined by EHT were all above 1.49 μg/ml. High frequencies of the resistant SNPs F200Y and F167Y alleles were detected but no resistance was detected at SNP E198A. Our results suggest that the SNPs F167Y and F200Y are both important for benzimidazole resistance in the studied populations. 相似文献
966.
A. Çevik‐Demirkan 《Anatomia, histologia, embryologia》2014,43(1):31-35
This study aimed to document the detailed features of the morphological structure and the innervation areas of the brachial plexus in Merlin (Falco columbarius). The skin and muscles of five adult male Merlins were dissected under the stereo microscope. The Merlin had two plexus trunks. The accessory brachial plexus consisted of ventral rami C10 and C11. C11 was divided into two branches: the cranial and caudal. The brachial plexus was composed of a rather complex network involving the ventral rami of C11‐C13, T1 and T2. In addition, a thin branch from the last two cervical sympathetic nerves participated in the plexus formation. C12, C13 and T1 had rather thick trunk. C12, C13 and T1 were also involved in the formation of the brachial plexus emerging after 1 cm from the foramen inter‐vertebrale as three trunk roots. 相似文献
967.
I. François F.‐X. Lalèyê M. Micat K. Benredouane K. Portier 《Equine veterinary journal》2014,46(5):596-600
968.
969.
970.
R. Smith W. McIlwraith R. Schweitzer K. Kadler J. Cook B. Caterson S. Dakin D. Heinegård H. Screen S. Stover N. Crevier‐Denoix P. Clegg M. Collins C. Little D. Frisbie M. Kjaer R. van Weeren N. Werpy J.‐M. Denoix A. Carr A. Goldberg L. Bramlage M. Smith A. Nixon 《Equine veterinary journal》2014,46(1):4-9