全文获取类型
收费全文 | 507篇 |
免费 | 32篇 |
专业分类
林业 | 4篇 |
农学 | 1篇 |
14篇 | |
综合类 | 256篇 |
农作物 | 3篇 |
水产渔业 | 17篇 |
畜牧兽医 | 219篇 |
园艺 | 2篇 |
植物保护 | 23篇 |
出版年
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 17篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 15篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2004年 | 15篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1970年 | 21篇 |
1969年 | 30篇 |
1968年 | 32篇 |
1967年 | 28篇 |
1966年 | 28篇 |
1963年 | 44篇 |
1960年 | 2篇 |
1934年 | 3篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
91.
(E, E)-10,12-hexadecadienal (HDD) effectively attracted males ofEarias insulana (Boisduval) when released from polyethylene vials but not from rubber dispensers. Traps baited with 3 mg HDD/trap were as effective in luring males as traps baited with four virgin females. Funnel traps baited with either HDD or virgin females captured significantly more males than water traps baited with the same lures. 相似文献
92.
CASE HISTORY: A 14-year-old neutered male Bearded Collie was presented with a history of recurrent, intermittent urinary incontinence of 7 years duration. CLINICAL FINDINGS: A large, firm, non-painful mass was found in the mid-abdominal region on palpation. Ultrasonography of the mass revealed a compartmentalised structure with mixed echogenicity, and which did not appear to be associated with any of the abdominal organs. Ultrasound-guided fine needle aspirates contained several clusters of epithelial cells with cytological features of hepatocytes. At exploratory laparotomy, the mass was found in the gastrosplenic ligament within the greater omentum. PATHOLOGICAL FINDINGS AND DIAGNOSIS: Histopathologically, the mass consisted of sheets of hepatocytes, but without the characteristic hepatic architecture. The cells showed moderate variation in nuclear size and were sometimes binucle- ate. A diagnosis of hepatocellular carcinoma (HCC) in the mesentery was made. CLINICAL RELEVANCE: The presence of ectopic hepatic tissue has been reported rarely in man and cats, but not in the dog. Neoplastic transformation of ectopic hepatic tissue is seen in man. This is the first report of the presentation, clinical findings and treatment of a dog with ectopic HCC. 相似文献
93.
94.
95.
96.
Abstract – Alternative reproductive tactics are commonly reported for salmonids (Pisces) and typically involve large migratory and small resident individuals. Variation in migratory tendency should reflect the different benefits and costs that the two different phenotypes face with regard to fitness. Therefore, the effect of food availability on the adoption of a migratory tactic in brown trout was investigated. Fifty trout were placed in each of 12 tanks and fed at three different levels. Growth-related variables were measured regularly, and at the end of the experiment, the proportion of migrants and residents was recorded. Low food availability led to increased numbers of migratory fish. The expected sex-bias was also present, with a lower percentage of resident females than resident males. As all fish originated from the same gene pool, the changing proportions of the migratory tactics can be classified as phenotypic plasticity. The study provides evidence that the different phenotypes reflect alternative tactics within a conditional strategy. Some differences in growth-related variables were present between the sexes, and a very pronounced difference in condition factor was found between resident and migratory males, but not in females. Thus, the results provide evidence that different selective forces may be acting on the sexes. 相似文献
97.
Surgical resection of a dysgerminoma in a mare 总被引:1,自引:1,他引:0
A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin. 相似文献
98.
Equine amnionitis and fetal loss: The case definition for an unrecognised cause of abortion in mares
KH Todhunter NR Perkins RM Wylie C Chicken AJ Blishen DJ Racklyeft G Muscatello MC Wilson PL Adams JR Gilkerson WL Bryden AP Begg 《Australian veterinary journal》2009,87(1-2):35-38
A series of abortions occurred in mares in New South Wales during 2004 that involved similar and unusual findings on post mortem examination of aborted fetuses and fetal membranes. The term Equine Amnionitis and Fetal Loss (EAFL) was developed to describe the condition. This form of abortion had not been previously recognised in Australia. The pathology alone is not specific for EAFL and diagnosis requires demonstration of a combination of certain pathological and bacteriological features. The purpose of this paper is to describe patterns considered consistent with EAFL cases as a working case definition for use by veterinarians and veterinary pathologists in identifying future cases of EAFL. More detailed papers are in preparation to fully describe the epidemiological, histopathological, and microbiological aspects of EAFL. 相似文献
99.
Charlotte E. Matthews Christopher E. Moorman Cathryn H. Greenberg Thomas A. Waldrop 《Forest Ecology and Management》2009
Fuel hazards have increased in forests across the United States because of fire exclusion during the 20th century. Treatments used to reduce fuel buildup may affect wildlife, such as shrews, living on the forest floor, especially when treatments are applied repeatedly. From mid-May to mid-August 2006 and 2007, we used drift fences with pitfall traps to capture shrews in western North Carolina in 3 fuel reduction treatment areas [(1) twice-burned (2003 and 2006), (2) mechanical understory cut (2002), and (3) mechanical understory cut (2002) followed by 2 burns (2003 and 2006)] and a control. We captured 77% fewer southeastern shrews (Sorex longirostris) in mechanical + twice-burned treatment areas than in mechanical treatment areas in 2006, but southeastern shrew captures did not differ among treatment areas in 2007. Total shrew captures did not differ among treatment areas in either year. Decreases in leaf litter, duff depth, and canopy cover in mechanical + twice-burned treatment areas may have decreased ground-level moisture, thereby causing short-term declines in southeastern shrew captures. Prescribed fire or mechanical fuel reduction treatments in the southern Appalachian Mountains did not greatly affect shrew populations, though the combination of both treatments may negatively affect some shrew species, at least temporarily. 相似文献
100.