全文获取类型
收费全文 | 6754篇 |
免费 | 559篇 |
国内免费 | 111篇 |
专业分类
林业 | 644篇 |
农学 | 296篇 |
基础科学 | 71篇 |
1795篇 | |
综合类 | 379篇 |
农作物 | 384篇 |
水产渔业 | 813篇 |
畜牧兽医 | 2301篇 |
园艺 | 142篇 |
植物保护 | 599篇 |
出版年
2023年 | 53篇 |
2022年 | 70篇 |
2021年 | 166篇 |
2020年 | 214篇 |
2019年 | 231篇 |
2018年 | 300篇 |
2017年 | 332篇 |
2016年 | 305篇 |
2015年 | 245篇 |
2014年 | 296篇 |
2013年 | 475篇 |
2012年 | 553篇 |
2011年 | 577篇 |
2010年 | 387篇 |
2009年 | 321篇 |
2008年 | 392篇 |
2007年 | 370篇 |
2006年 | 308篇 |
2005年 | 315篇 |
2004年 | 264篇 |
2003年 | 252篇 |
2002年 | 208篇 |
2001年 | 149篇 |
2000年 | 136篇 |
1999年 | 97篇 |
1998年 | 57篇 |
1997年 | 52篇 |
1996年 | 31篇 |
1995年 | 40篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 18篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1969年 | 3篇 |
1918年 | 5篇 |
1911年 | 2篇 |
1863年 | 2篇 |
排序方式: 共有7424条查询结果,搜索用时 364 毫秒
1.
2.
Mattana Efisio Peguero Brígido Di Sacco Alice Agramonte Wilvin Encarnación Castillo Wilkin Rafael Jiménez Francisco Clase Teodoro Pritchard Hugh W. Gómez-Barreiro Pablo Castillo-Lorenzo Elena Terrero Encarnación Marianny Way Michael J. García Ricardo Ulian Tiziana 《New Forests》2020,51(4):705-721
New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected... 相似文献
3.
4.
M D Pérez Alenza E Tabanera L Pe?a 《Journal of the American Veterinary Medical Association》2001,219(8):1110-1114
OBJECTIVE: To determine epidemiologic, clinical, and pathologic characteristics of inflammatory mammary carcinoma (IC) in dogs. DESIGN: Retrospective study. ANIMALS: 33 dogs with IC and 153 dogs with malignant mammary tumors other than IC. PROCEDURES: Medical records were reviewed, and signalment, history, physical examination findings, and results of thoracic radiography and necropsy were obtained. RESULTS: 33 of 436 (7.6%) dogs examined at a veterinary teaching hospital because of dysplasia or tumors of the mammary glands and 33 of 186 (17.7%) dogs with at least 1 malignant tumor had IC. Thirty-two of the 33 dogs were sexually intact. Dogs with IC were significantly older than were dogs with other malignant mammary tumors, and in dogs with IC, the tumor was initially noticed a mean of 52 days after the beginning of the last observed estrus, whereas in dogs with other mammary tumors, the tumor was initially noticed a mean of 137 days after the beginning of the last observed estrus. Dogs with IC were more likely to be anorectic and to have generalized weakness, weight loss, and thoracic metastases. Dogs with IC survived a mean of 25 days with palliative treatment. Histologically, involvement of dermal lymphatic vessels was identified in 14 of 19 (74%) dogs with IC. Two clinical forms of IC (primary and secondary) were identified. Dogs with primary IC had a worse clinical condition. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that IC is an uncommon but distinct entity in dogs. A histologic finding of dermal lymphatic involvement should be considered a hallmark for the pathologic diagnosis of IC in dogs. 相似文献
5.
6.
7.
M. P. Reche P. A. Jimnez F. Alvarez J. E. García de los Ríos A. M. Rojas P. De Pedro 《Zoonoses and public health》2003,50(1):42-44
A total of 595 faecal samples from raptorial birds, either captive or free‐living, residing in GREFA Wildlife Hospital were bacteriologically examined using various selective media and an Automated Diagnostic Assay System for Salmonella detection. Serotype and phage type of the strains identified as Salmonella was determined. In the captive group, of the 285 samples examined, 21 (7.36%) were positive for Salmonella. Serotyping revealed that most of the individuals were infected by Salmonella serotype Havana. This result suggested that there could be a source of contamination in the Hospital although it could not be established. In the wild free‐living group, over 310 samples examined (4.19%) were positive for Salmonella. The Salmonella isolates showed a major variety of serotypes: Enteritidis, Adelaide, Brandenburg, Newport, Typhimurium, Hadar, Saintpaul and Virchow. Most of them are similar to those commonly described in isolates from human and domestic animals. These results indicate that wild birds could be involved in the dissemination of Salmonella in humans or domestic animals or vice versa. 相似文献
8.
B Cancho Grande M S García Falcón M Rodríguez Comesa?a J Simal Gándara 《Journal of agricultural and food chemistry》2001,49(7):3145-3150
Sulfamethazine (SMZ) and trimethoprim (TMP) are antibacterials used in veterinary practice. This paper describes a method for their determination in veterinary liquid feed premixes that is based on liquid chromatography with diode array detection. Gradient elution with methanol and ammonium acetate achieved excellent separation of the two analytes within 15 min without any interference from the matrix. Absorbance of the column effluent was monitored at 264 nm for SMZ and at 230 nm for TMP. Detailed analyses of the uncertainties of determinations afford estimated expanded uncertainties of, respectively, 0.2 and 0.1 w/v % for typical SMZ and TMP concentrations of 10.7 and 2.1 w/v %, respectively. At the lower end of the calibrated range of the method, the dominant source of uncertainty is the preparation of standards and the construction of the calibration line. 相似文献
9.
10.