全文获取类型
收费全文 | 25654篇 |
免费 | 608篇 |
国内免费 | 8篇 |
专业分类
林业 | 6291篇 |
农学 | 1499篇 |
基础科学 | 171篇 |
4373篇 | |
综合类 | 945篇 |
农作物 | 2524篇 |
水产渔业 | 2352篇 |
畜牧兽医 | 4351篇 |
园艺 | 1227篇 |
植物保护 | 2537篇 |
出版年
2023年 | 61篇 |
2022年 | 71篇 |
2021年 | 130篇 |
2020年 | 152篇 |
2019年 | 83篇 |
2018年 | 2942篇 |
2017年 | 2943篇 |
2016年 | 1458篇 |
2015年 | 296篇 |
2014年 | 327篇 |
2013年 | 538篇 |
2012年 | 1283篇 |
2011年 | 2560篇 |
2010年 | 2347篇 |
2009年 | 1474篇 |
2008年 | 1670篇 |
2007年 | 1910篇 |
2006年 | 337篇 |
2005年 | 433篇 |
2004年 | 445篇 |
2003年 | 452篇 |
2002年 | 311篇 |
2001年 | 190篇 |
2000年 | 205篇 |
1999年 | 132篇 |
1997年 | 69篇 |
1996年 | 91篇 |
1995年 | 68篇 |
1994年 | 70篇 |
1993年 | 88篇 |
1992年 | 100篇 |
1991年 | 75篇 |
1990年 | 72篇 |
1989年 | 83篇 |
1988年 | 74篇 |
1987年 | 72篇 |
1986年 | 65篇 |
1985年 | 57篇 |
1984年 | 61篇 |
1983年 | 65篇 |
1982年 | 66篇 |
1981年 | 113篇 |
1980年 | 62篇 |
1979年 | 91篇 |
1953年 | 61篇 |
1938年 | 58篇 |
1933年 | 54篇 |
1932年 | 50篇 |
1926年 | 74篇 |
1925年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Dr.-Ing. Alexander Friedl 《Journal of pest science》1938,14(12):137-140
Ohne Zusammenfassung 相似文献
4.
Juan Pablo Zoffoli Bernardo A. Latorre Paulina Naranjo 《Postharvest Biology and Technology》2009,51(2):183-192
Over 54,600 ha of table grapes (Vitis vinifera), mainly cvs. ‘Thompson Seedless’, ‘Flame Seedless’ and ‘Redglobe’, are planted in Chile. Almost the entire production is exported to the USA, Europe, Asia, or one of several Latin American countries, which typically requires 15–40 d of maritime transportation. During this period, several physical, physiological, and pathological factors cause table grape deterioration. Because berry size is the main quality factor in international markets, farmers often overuse the growth regulators, gibberellic acid (GA3) and forchlorfenuron (CPPU), in an effort to increase berry size. We examined the effect of preharvest growth regulators on seedless (‘Thompson Seedless’, and ‘Ruby Seedless’) and seeded (‘Redglobe’) table grape cultivars during cold (0 °C) storage plus a shelf life period of 3 d at 20 °C. The overuse of GA3, eight instead of two GA3 applications on Thompson Seedless, and the use of one GA3 application on Redglobe and ‘Ruby Seedless’, increased berry pedicel thickness and lowered cuticle content but induced shatter and predisposed grapes to gray mold caused by Botrytis cinerea. In contrast, CPPU increased berry pedicel thickness and cuticle content but did not increase shatter or gray mold incidence. Clusters that were subjected to overuse of combined GA3 and CPPU were highly sensitive to shatter, had the thickest pedicel, and developed a high gray mold incidence during cold storage. Hairline, a fine cracking developed during cold storage, was induced on ‘Thompson Seedless’ and ‘Ruby Seedless’ by growth regulators, but no hairline occurred on ‘Redglobe’ table grapes. Therefore, berry quality during cold storage is greatly influenced by growth regulator management in the vineyard. 相似文献
5.
J L López-Rivero E Agüera J G Monterde J Vivo M V Rodríguez-Barbudo 《American journal of veterinary research》1992,53(5):847-850
The mean area and minimal diameter of 3 histochemically determined myofiber types (1, 2A, and 2B; myosin ATPase in acid buffer) were calculated in middle gluteal muscle biopsy specimens from 62 stallions, 47 Andalusians and 15 Arabians, ranging in age from 6 to 12 years. Fourteen Andalusians and 7 Arabians were untrained, and the remainder were actively endurance-trained. The 6-month training schedules involved walking, slow trotting, and cantering. Fourteen Andalusians were moderately endurance-trained, whereas the other 19 Andalusians and 8 Arabians were strongly endurance-trained. Significant differences were not recorded between untrained and endurance-trained Arabians with respect to the area (type 1, 3,194 +/- 869 microns 2 and 3,150 +/- 370 microns 2; type 2A, 3,819 +/- 890 microns 2 and 3,380 +/- 356 microns 2; and type 2B, 4,872 +/- 962 microns 2 and 4,417 +/- 646 microns 2) or minimal diameter (type 1, 52.2 +/- 7.4 microns and 52.8 +/- 3.1 microns; type 2A, 58.1 +/- 6.7 microns and 55.0 +/- 2.8 microns; and type 2B, 65.3 +/- 6.4 microns and 63.4 +/- 4.3 microns) of the 3 fiber types, nor between untrained and endurance-trained Andalusians with respect to the area (untrained, 3,990 +/- 690 microns 2; moderately endurance-trained, 3,882 +/- 347 microns 2; and strongly endurance-trained, 3,758 +/- 510 microns 2) and minimal diameter (untrained, 58.1 +/- 4.7 microns; moderately endurance-trained, 59.7 +/- 2.7 microns; and strongly endurance-trained, 58.7 +/- 4.5 microns) of 2A fibers.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
7.
8.
9.
Dr. Oskar Bernbeck 《European Journal of Forest Research》1911,33(4):210-211
10.
Martin Kramer Dr. Med. Vet Martin Gerwing Dr. Med. Vet Volker Hach Dr. Med. Vet Ernst Schimke Prof. Dr. Med. Vet 《Veterinary radiology & ultrasound》1997,38(2):139-149
Sonography of the musculoskeletal system in dogs and cats was undertaken to evaluate the application of this imaging procedure in orthopedics. In most of the patients a 7,5 MHz linear transducer was used because of its flat application surface and its resolving power. The evaluation of bone by sonography is limited, but sonography can provide addition information regarding the bone surface and surrounding soft tissue. Ultrasound is valuable for assessing joint disease. Joint effusion, thickening of the joint capsule and cartilage defects can be identified sonographically. It is also possible to detect bone destruction. Instabilities are often identified with the help of a dynamic examination. Soft tissue abnormalities of the musculoskeletal system lend themselves to sonographic evaluation. Partial or complete muscles or tendon tears are able to be differentiated and the healing process can be monitored. Most of the diseases that are in the area of the biceps or the achilles tendon, such as dislocation of the tendon, old injuries with scarification, free dissecates in the tendonsheath, tendinitis and/or tendosynovitis can be differentiated by sonography. In addition, with clinical and laboratory findings, it is often possible to make a correct diagnosis with ultrasound in patients with abscesses, foreign bodies, hematomas, soft tissue tumors and lipomas. 相似文献