全文获取类型
收费全文 | 5551篇 |
免费 | 248篇 |
国内免费 | 4篇 |
专业分类
林业 | 423篇 |
农学 | 209篇 |
基础科学 | 35篇 |
1101篇 | |
综合类 | 877篇 |
农作物 | 231篇 |
水产渔业 | 344篇 |
畜牧兽医 | 2002篇 |
园艺 | 176篇 |
植物保护 | 405篇 |
出版年
2023年 | 33篇 |
2022年 | 54篇 |
2021年 | 84篇 |
2020年 | 135篇 |
2019年 | 126篇 |
2018年 | 135篇 |
2017年 | 121篇 |
2016年 | 130篇 |
2015年 | 110篇 |
2014年 | 131篇 |
2013年 | 260篇 |
2012年 | 303篇 |
2011年 | 383篇 |
2010年 | 224篇 |
2009年 | 171篇 |
2008年 | 315篇 |
2007年 | 318篇 |
2006年 | 294篇 |
2005年 | 290篇 |
2004年 | 266篇 |
2003年 | 272篇 |
2002年 | 257篇 |
2001年 | 65篇 |
2000年 | 71篇 |
1999年 | 82篇 |
1998年 | 57篇 |
1997年 | 54篇 |
1996年 | 55篇 |
1995年 | 41篇 |
1994年 | 47篇 |
1993年 | 49篇 |
1992年 | 41篇 |
1991年 | 47篇 |
1990年 | 46篇 |
1989年 | 42篇 |
1988年 | 38篇 |
1987年 | 39篇 |
1986年 | 54篇 |
1985年 | 32篇 |
1984年 | 43篇 |
1983年 | 35篇 |
1982年 | 36篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 23篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1975年 | 20篇 |
1973年 | 24篇 |
1972年 | 20篇 |
排序方式: 共有5803条查询结果,搜索用时 15 毫秒
131.
Thomas G. Nyland DVM Brett M. Kantrowitz DVM †Paul Fisher Harvey J. Olander DVM PHD‡ William J. Hornof DVM MS 《Veterinary radiology & ultrasound》1989,30(4):174-180
Canine kidney measurements were obtained in vivo using ultrasound before and after anesthesia and were compared with direct caliper measurements at laparotomy. Following excision, the kidney dimensions were also measured ultrasonically in a water bath and the results were used to calculate kidney -volume by a modified parallel planimetric method and three variations of a prolate ellipsoid method. The calculated volume was compared with actual kidney volume determined by volume displacement. All methods were found to underestimate actual volume so that a linear correction of ultrasonically calculated volume was required to predict actual volume. The modified parallel planimetric method and a prolate ellipsoid method using height and width determinations cranial and caudal to the renal pelvis were the best models. The prolate ellipsoid model was chosen for subsequent kidney volume calculations because of its simplicity. The noninvasive calculation of kidney volume using ultrasound was sufficiently accurate to be clinically useful, particularly when serially evaluating kidney size changes in the same dog. 相似文献
132.
Sakamoto K Lewbart GA Smith TM 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2001,30(2):50-52
Abstract: Blood samples were collected from 29 juvenile red pacu ( Piaractus brachypomus ), ornamental freshwater fish, to establish baseline blood chemistry values. Mean (minimum-maximum) values, obtained by automated bichromatic analysis and ion selective electrode analysis, were as follows: sodium, 150.4 (146–159) mmol/L; potassium, 3.93 (2.7–5.0) mmol/L; chloride, 138.7 (128–150) mmol/L; total CO2 , 7.5 (6–10) mmol/L; albumin, 0.86 (0.5–1.0) g/dL; lactate dehydrogenase, 237.8 (65–692) IU/L; aspartate aminotransferase, 49.1 (0–125) IU/L; creatinine, 0.31 (0.2–0.4) mg/dL; calcium, 10.80 (9.5–12.5) mg/dL; anion gap, 6.89 (1.2–12.5) mmol/L; and phosphorus, 7.29 (4.1–8.9) mg/dL. 相似文献
133.
134.
Six RH Clemence RG Thomas CA Behan S Boy MG Watson P Benchaoui HA Clements PJ Rowan TG Jernigan AD 《Veterinary parasitology》2000,91(3-4):291-309
A series of randomized, controlled and masked field studies was conducted in veterinary patients to evaluate the efficacy of selamectin, a novel avermectin, in the treatment of naturally occurring Sarcoptes scabiei infestations on dogs and Otodectes cynotis infestations on dogs and cats. A total of 342 dogs and 237 cats participated in these studies, which were conducted at 40 veterinary practices in the USA and Europe. Animals were randomly assigned to treatment with selamectin or a positive-control product (existing approved products). Selamectin was administered as a unit dose providing a minimum of 6mgkg(-1) (range: 6-12mgkg(-1)) in a topical preparation applied to the skin in a single spot on day 0 (O. cynotis in cats, n=144), or on days 0 and 30 (O. cynotis and S. scabiei in dogs, n=83 and n=122, respectively). The presence of parasites was assessed before treatment and at 30 days (for all studies) and 60 days (for O. cynotis and S. scabiei dog studies) after first treatment. The animals were also evaluated clinically at each assessment period. Based on skin scrapings, the efficacy of selamectin against S. scabiei infestations on dogs was >95% by day 30, and 100% by day 60. Against O. cynotis, selamectin eliminated mites in 94-100% of cats by day 30, and in 90% of dogs by day 60. The positive-control products achieved similar results. Thus, selamectin was safe and effective against ear mites in dogs and cats and sarcoptic mange in dogs when used in field (veterinary patient) studies in dogs and cats of a wide variety of ages and breeds. 相似文献
135.
136.
137.
Amir N Hamir Thomas Gidlewski Terry R Spraker Janice M Miller Lynn Creekmore Michelle Crocheck Thomas Cline Katherine I O'Rourke 《Journal of veterinary diagnostic investigation》2006,18(1):110-114
To compare the genetic susceptibility of elk (Cervus elaphus nelsoni) with various alleles of the PRNP gene, which encodes the normal cellular prion protein, to chronic wasting disease (CWD), eight 8-month-old elk calves of 3 genotypes (2 132MM, 2 132LM, and 4 132LL) were orally dosed with CWD-infected brain material from elk. During postinoculation (PI) month 23, both 132MM elk had lost appetite, developed clinical signs of weight loss and central nervous system (CNS) dysfunction, and were euthanized. Two other elk (both 132LM) developed similar clinical signs of disease and were euthanized during PI month 40. All 4 affected elk had microscopic lesions of spongiform encephalopathy (SE), and PrPres, the disease-associated form of the prion protein, was detected in their CNS and lymphoid tissues by use of immunohistochemical (IHC) and Western blot (WB) techniques. These findings indicate that elk with MM and LM at codon 132 are susceptible to orally inoculated CWD. All 4 LL elk are alive at PI year 4 and are clinically normal, which suggests that 132LL elk may have reduced susceptibility to oral infection with CWD-infected material or may have prolonged incubation time. 相似文献
138.
Cate E. Dewey W. Thomas Johnston Loriena Gould Terry L. Whiting 《Canadian journal of veterinary research》2006,70(3):161-167
A case-control study to investigate the contribution of postweaning multisystemic wasting syndrome (PMWS) and Porcine circovirus type 2 (PCV-2) to deaths among piglets of nursery age (19 to 68 d) in Manitoba indicated a significant positive association between PCV-2 infection and an increased mortality rate in nursery pigs. The clinical syndrome PMWS was seldom recognized in case or control herds; however, PCV-2 infection was widespread at the herd level. Other factors more strongly associated with increased piglet mortality rate than herd level PCV-2 infection were Mycoplasma hyopneumonia infection, porcine reproductive and respiratory syndrome (PRRS), and diarrhea caused by Eschericia coli K88. Management factors associated with case herd status included close proximity to other herds, larger number of sows supplying pigs to the nursery, larger range in age and weight going into the nursery, the moving of lightweight pigs into another nursery room at the end of the nursery fill, and not using spray-dried plasma in the 1st nursery ration. These results highlight the host-agent-environment triad leading to high nursery-barn mortality rates. 相似文献
139.
Jrme Van Biervliet DVM Dipl ACVIM Marc Kraus DVM Dipl ACVIM Brett Woodie DVM Dipl ACVS Thomas J. Divers DVM Dipl ACVIM Dipl ACVECC Anna Gelzer Dr. Med. Vet. Dipl ACVIM Dorothy Ainsworth DVM PhD Dipl ACVIM 《Journal of Veterinary Cardiology》2006,8(1):69-73
A 5-year-old Holstein cow, pregnant with a valuable calf, was presented with signs of heart failure (tachycardia, peripheral edema, and distended jugular veins) related to pericardial lymphoma and associated cardiac tamponade. In addition, pleural effusion was present in both hemithoraces. Medical treatment, which consisted of repeated pericardiocenteses, placement of indwelling pleural catheters, administration of intravenous fluid therapy, antibiotics and anti-inflammatory drugs, was ineffective in controlling recurrence of clinical signs despite a temporary improvement. A standing thoracoscopic pericardiotomy was performed in an attempt to reduce clinical signs of heart failure and to prolong life. Clinical signs of heart failure abated and no recurrence was seen. Standing thoracoscopic pericardiotomy along with possible corticosteroids can be recommended as palliative treatment in an effort to extend life for reproductive performance in genetically valuable animals. 相似文献
140.
Kurkure NV Pande VV Thomas F Bhandarkar AG 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2006,53(1):22-23
A case of seminoma in a monorchid adult guinea fowl (Numida meleagris) is described. Grossly, a right enlarged testis, which was soft in consistency, and white to pale in colour with few spots of haemorrhages was observed. Histologically, the testicle revealed diffusely spread sheets of tumour cells. The cells were large pleomorphic with eccentrically placed hyperchromic nuclei. Mitotic figures were evident. A scanty fibrous stroma, containing lymphocytes and histiocytes, separating the groups of tumour cells, along with few areas of haemorrhages were observed. Occurrence of seminoma in guinea fowl is unusual and hence reported. 相似文献