全文获取类型
收费全文 | 129277篇 |
免费 | 7725篇 |
国内免费 | 651篇 |
专业分类
林业 | 5253篇 |
农学 | 4004篇 |
基础科学 | 917篇 |
15026篇 | |
综合类 | 24515篇 |
农作物 | 4600篇 |
水产渔业 | 6006篇 |
畜牧兽医 | 67761篇 |
园艺 | 1721篇 |
植物保护 | 7850篇 |
出版年
2019年 | 1313篇 |
2018年 | 1974篇 |
2017年 | 2202篇 |
2016年 | 1971篇 |
2015年 | 1856篇 |
2014年 | 2090篇 |
2013年 | 4997篇 |
2012年 | 4057篇 |
2011年 | 4934篇 |
2010年 | 3248篇 |
2009年 | 3132篇 |
2008年 | 4485篇 |
2007年 | 4359篇 |
2006年 | 4004篇 |
2005年 | 3754篇 |
2004年 | 3437篇 |
2003年 | 3538篇 |
2002年 | 3348篇 |
2001年 | 3815篇 |
2000年 | 3860篇 |
1999年 | 3033篇 |
1998年 | 1284篇 |
1997年 | 1188篇 |
1995年 | 1263篇 |
1994年 | 1147篇 |
1993年 | 1136篇 |
1992年 | 2479篇 |
1991年 | 2775篇 |
1990年 | 2605篇 |
1989年 | 2582篇 |
1988年 | 2414篇 |
1987年 | 2414篇 |
1986年 | 2491篇 |
1985年 | 2351篇 |
1984年 | 1979篇 |
1983年 | 1743篇 |
1982年 | 1168篇 |
1979年 | 1794篇 |
1978年 | 1424篇 |
1977年 | 1274篇 |
1976年 | 1306篇 |
1975年 | 1368篇 |
1974年 | 1695篇 |
1973年 | 1689篇 |
1972年 | 1625篇 |
1971年 | 1493篇 |
1970年 | 1500篇 |
1969年 | 1420篇 |
1968年 | 1208篇 |
1967年 | 1256篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Hege Kippenes DVM Patrick R. Gavin DVM PhD Susan L. Kraft DVM PhD Ronald D. Sande DVM MS PhD Russell L. Tucker DVM 《Veterinary radiology & ultrasound》2001,42(2):130-133
The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy. 相似文献
72.
B. Götz 《Journal of pest science》1938,14(8):92-93
Ohne Zusammenfassung 相似文献
73.
G. L. RICHARDSON dvm T. R. O'BRIEN dvm PhD Diplomateacvr J. R. PASCOE bvsc D. M. MEAGHER dvm PhD Dipiomateacvs 《Veterinary surgery : VS》1986,15(2):156-160
The medical records of 38 horses with puncture wounds of the navicular bursa were reviewed. Only 12 horses had a satisfactory outcome (breeding or riding). Of the remaining 26 horses, 19 were euthanized, five were sold due to persistent severe lameness, one died, and one was lost to long-term follow-up. Different combinations of conservative management prior to surgical debridement and drainage of the navicular bursa were unsuccessful in resolving the condition. Horses that were treated surgically within 1 week of the injury and had a hind leg affected had the best chance of a satisfactory outcome. Additional wound debridement was necessary in 15 horses after initial surgical treatment. The most common complications encountered were navicular bone osteomyelitis and sepsis of the deep digital flexor tendon. Thirteen of 14 horses that had rupture of the deep digital flexor tendon and subluxation of the distal interphalangeal joint had an unsatisfactory outcome. One mare subsequently developed ankylosis of the distal interphalangeal joint and was a useful brood mare. Two horses that had biaxial palmar digital neurectomy because of persistent lameness were later euthanized because of navicular bone fracture and rupture of the deep digital flexor tendon. Results from limited numbers of bacterial cultures and antibiotic sensitivities suggest that penicillin and an aminoglycoside antibiotic should be used as initial antibiotic therapy. Immediate surgical debridement and appropriate antibiotic treatment are recommended as the minimum therapy for penetrating wounds of the navicular bursa in horses. 相似文献
74.
Asymmetric illumination contrast: a method of image formation for video light microscopy 总被引:4,自引:0,他引:4
B Kachar 《Science (New York, N.Y.)》1985,227(4688):766-768
Images with high resolution and exceptionally broad gray scale can be obtained by the application of video contrast enhancement to an optimized procedure for imaging transparent objects with oblique rays of illumination. This technique is simple to set up. A conventional microscope with a light source whose position can be adjusted and a video camera with controls for gain and black level are the only essential components. Features such as high resolution, optical sectioning, control of contrast, and operation under low light intensity make this technique preferable, in several instances, to currently used video microscopy techniques. 相似文献
75.
Washed and unwashed red blood cells (RBC) from young calves, adult cattle, hamsters and humans were incubated with Leptospira interrogans serovars pomona and ballum. Washed cells suspended in saline were always haemolysed while unwashed cells and those which were washed and resuspended in plasma were never haemolysed, despite the presence of large numbers of organisms within the culture supernatant. Pomona produced greater haemolysis of cattle and human RBC than did ballum, but with hamster RBC ballum produced greater haemolysis than did pomona. A group of 6- to 9-month-old cattle infected with pomona showed no signs of clinical disease and RBC taken from them before infection and during the development of antibodies to pomona were haemolysed by pomona only after the cells were washed. Plasma therefore appears to have a protective function. This in vitro protective function of plasma even extended to plasma from young seronegative calves. 相似文献
76.
Softening process and total antioxidant activity were evaluated in kiwifruit differently exposed to light intensity and harvested at two different times (October 10 and November 14). Fruit was stored for 2 months at 0 °C (S1) and then maintained for a week at ambient temperature (S2). The results showed that fruit harvested later presented a faster softening rate during storage than fruit harvested earlier, even if antioxidant activity did not change. Light-exposed fruit showed higher flesh firmness than that of shaded ones. Polygalacturonase activity was higher in kiwifruit maintained for a week at ambient temperature after cool storage and, in particular the highest value was recorded in fruit harvested later. The behaviour of β-galactosidase was different: it did not show changes in fruit harvested later and significantly decreased in light- and shade-exposed fruit harvested earlier. 相似文献
77.
78.
79.
80.