全文获取类型
收费全文 | 6882篇 |
免费 | 3366篇 |
专业分类
林业 | 200篇 |
农学 | 451篇 |
基础科学 | 3篇 |
1364篇 | |
综合类 | 37篇 |
农作物 | 229篇 |
水产渔业 | 2508篇 |
畜牧兽医 | 4180篇 |
园艺 | 12篇 |
植物保护 | 1264篇 |
出版年
2023年 | 4篇 |
2022年 | 18篇 |
2021年 | 141篇 |
2020年 | 473篇 |
2019年 | 1028篇 |
2018年 | 914篇 |
2017年 | 942篇 |
2016年 | 948篇 |
2015年 | 836篇 |
2014年 | 821篇 |
2013年 | 1002篇 |
2012年 | 498篇 |
2011年 | 520篇 |
2010年 | 614篇 |
2009年 | 267篇 |
2008年 | 265篇 |
2007年 | 108篇 |
2006年 | 132篇 |
2005年 | 102篇 |
2004年 | 106篇 |
2003年 | 98篇 |
2002年 | 118篇 |
2001年 | 77篇 |
2000年 | 112篇 |
1999年 | 13篇 |
1998年 | 2篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 4篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Cesar Consuegra Francisco Crespo Jesús Dorado Maria Diaz‐Jimenez Blasa Pereira Manuel Hidalgo 《Reproduction in domestic animals》2019,54(Z4):86-89
Lipids and proteins can be used for sperm vitrification to preserve the integrity of sperm membranes or to increase the viscosity of the medium. This study evaluated the effect of low‐density lipoproteins (LDL) and milk serum proteins (Pronexcell) for stallion sperm vitrification. Hippex extender (Barex Biochemical Products, The Netherlands), plus 1% of bovine serum albumin and 100 mM of trehalose, was used as control for sperm vitrification. In experiment 1, different concentrations of LDL (L1 = 0.25, L2 = 0.5, L3 = 1%) and in experiment 2 of Pronexcell (P1 = 1, P2 = 5, P3 = 10%) were added to control extender. Vitrification was performed in 0.25‐ml straws directly plunged into liquid nitrogen. Total motility (TM, %) and progressive motility (PM, %) were analysed by CASA, and plasma membrane (IMS, %) and acrosome membrane integrity (AIS, %) were assessed under epifluorescence microscopy. Post‐warmed sperm parameters were compared between treatments by ANOVA. Results were expressed as mean ± SEM. In both experiments, the minimum concentration of LDL and Pronexcell obtained significantly higher values (p < 0.01) than the control extender for TM (L1 = 52.95 ± 4.4; P1 = 58.99 ± 4.6; C = 30.88 ± 3.0), PM (L1 = 36.79 ± 5.5; P1 = 47.25 ± 4.3; C = 19.20 ± 2.4), IMS (L1 = 68.88 ± 3.6; P1 = 47.25 ± 4.3; C = 52.81 ± 2.6) and AIS (L1 = 45.88 ± 3.6; P1 = 47.25 ± 4.3; C = 26.00 ± 2.1). No differences in sperm parameters were found among different concentrations of LDL or Pronexcell. In conclusion, the addition of 0.25% LDL and 1% Pronexcell to the vitrification extender is recommended to improve the quality of stallion sperm after vitrification. 相似文献
92.
Rose L. Cherry Kryssa L. Johnson Adrien‐Maxence Hespel Karen M. Tobias Daniel A. Ward 《Veterinary ophthalmology》2019,22(3):353-359
A 2‐year‐old, male castrated German shepherd dog was presented to the University of Tennessee Veterinary Medical Center (UTVMC) with periorbital swelling and conjunctival mucopurulent discharge 2 days following removal of a twig from the medial canthus by the owner. Diagnostic imaging was pursued due to the suspicion of a retrobulbar foreign body (FB). A cylindrical FB approximately 3.0 cm in length and 1.0 cm in diameter with concentric rings, suspected to be wooden material, was identified on computed tomography (CT) imaging. An attempt to remove the FB via a stab incision using ultrasound guidance was unsuccessful, and postmanipulation ultrasound confirmed the FB position was unchanged. An exploratory orbitotomy was performed, using the acquired CT images for guidance in locating the FB; however, the FB was not present at the predicted site. The CT imaging was repeated and showed that the FB had migrated rostrally approximately 3.0 cm, compared to the originally acquired study and its same location during attempted ultrasound‐guided removal. A combination of CT‐guided needle placement and contrast injection was then used with repeat imaging in an attempt to better localize the FB and its soft tissue tract. The dog was taken back into the operating room, and the wooden FB was successfully removed. 相似文献
93.
94.
PB Fernandes KO Marques FR de Araujo Neto DP de Oliveira NA Hurtado‐Lugo RR Aspilcueta‐Borquis H Tonhati 《Reproduction in domestic animals》2016,51(3):428-434
Because of the importance of reproduction in stock breeding systems, it is necessary to find selection criteria that increase reproductive efficiency. The aim of this study was to estimate genetic parameters for the probability of conception on first service (PROB) in Murrah heifers, and its association with other traits of economic interest [age at first calving (AFC), service period, calving interval and milk yield at 270 days], with the purpose of evaluating their use as selection criteria. Reproductive information and first lactation records of 1200 Murrah heifers were used to perform two‐trait analyses between PROB and the other characteristics. Bayesian inference was used to estimate the variance components, considering PROB as threshold and the other as linear factors. The results demonstrate that this trait has heritability of 0.15, indicating the possibility of a genetic gain by using it for selection. With respect to the genetic correlation estimates, the only high‐magnitude association was with AFC (?0.899), which is the current criterion indicating sexual precocity of females. In the light of the parameters estimated, the first‐service pregnancy rate is an alternative for indication of sexual precocity, although presenting a smaller genetic gain than the current standard AFC. Nevertheless, additional research should be conducted regarding this trait to assess the economic importance of its use in dairy buffalo production systems. 相似文献
95.
96.
97.
Differentiation between dogs with thrombosis and normal dogs using the overall hemostasis potential assay 下载免费PDF全文
Anna L. Dengate BVSc BMedSc Marie‐Christine Morel‐Kopp PhD Julia A. Beatty PhD BVetMed BSc Vanessa Barrs BVSc MVetClinStud Jody A. Braddock BVSc MVetClinStud Richard K. Churcher BVSc Bethany J. Wilson BVSc PhD Christopher M. Ward BMedSc MBChB PhD 《Journal of Veterinary Emergency and Critical Care》2016,26(3):446-452
98.
Rita M. Hanel DVM DACVIM DACVECC Lee Palmer DVM MS DACVECC NREMT‐T WEMT CCRP Janice Baker DVM DACVPM Jo‐Anne Brenner BA EMT‐I EMT‐T David Dorman DVM PhD DABVT John C. Gicking DVM DACVECC Brian Gilger DVM MS DACVO DABT Cynthia M. Otto DVM PhD DACVECC DACVSMR Elizabeth Rozanski DVM DACVECC DACVIM Brian Trumpatori DVM 《Journal of Veterinary Emergency and Critical Care》2016,26(2):166-233
99.
IMAGING DIAGNOSIS—MULTIMODALITY FINDINGS IN AN ADULT DOG WITH PRIMARY SARCOMA OF THE PULMONARY ARTERY AND MYOCARDIAL METASTASES 下载免费PDF全文
Susanne M. Stieger‐Vanegas Bryan Bottorff David Sisson Christiane V. Löhr 《Veterinary radiology & ultrasound》2016,57(4):E34-E41
Intravascular pulmonary artery sarcomas in combination with myocardial metastasis are rare in dogs. We describe the radiographic, echocardiographic, and electrocardiographic‐gated (ECG‐gated) computed tomographic angiography (CTA) findings in a dog with pulmonary artery sarcoma. All imaging studies demonstrated severe main pulmonary artery enlargement. Echocardiography and ECG‐gated CTA revealed a mass occluding the lumen of the right pulmonary artery. In addition, CTA revealed focal left ventricular myocardial contrast enhancement and parenchymal lung changes. Postmortem examination confirmed the presence of a large thrombus associated with arteriosclerosis and an intravascular sarcoma in the right pulmonary artery with metastases to the myocardium, lungs and brain. 相似文献
100.