全文获取类型
收费全文 | 160581篇 |
免费 | 9081篇 |
国内免费 | 352篇 |
专业分类
林业 | 6628篇 |
农学 | 5584篇 |
基础科学 | 1110篇 |
21252篇 | |
综合类 | 23071篇 |
农作物 | 6071篇 |
水产渔业 | 8228篇 |
畜牧兽医 | 85184篇 |
园艺 | 2129篇 |
植物保护 | 10757篇 |
出版年
2020年 | 1444篇 |
2019年 | 1706篇 |
2018年 | 2671篇 |
2017年 | 2957篇 |
2016年 | 2738篇 |
2015年 | 2370篇 |
2014年 | 2919篇 |
2013年 | 6847篇 |
2012年 | 5081篇 |
2011年 | 6062篇 |
2010年 | 4149篇 |
2009年 | 4212篇 |
2008年 | 5997篇 |
2007年 | 5734篇 |
2006年 | 5399篇 |
2005年 | 4872篇 |
2004年 | 4702篇 |
2003年 | 4767篇 |
2002年 | 4368篇 |
2001年 | 5498篇 |
2000年 | 5347篇 |
1999年 | 4260篇 |
1998年 | 1736篇 |
1997年 | 1726篇 |
1996年 | 1573篇 |
1995年 | 1849篇 |
1994年 | 1550篇 |
1993年 | 1543篇 |
1992年 | 3207篇 |
1991年 | 3427篇 |
1990年 | 3316篇 |
1989年 | 3391篇 |
1988年 | 3061篇 |
1987年 | 3007篇 |
1986年 | 2996篇 |
1985年 | 2806篇 |
1984年 | 2277篇 |
1983年 | 1986篇 |
1982年 | 1344篇 |
1979年 | 2080篇 |
1978年 | 1620篇 |
1977年 | 1407篇 |
1976年 | 1385篇 |
1975年 | 1465篇 |
1974年 | 1723篇 |
1973年 | 1831篇 |
1972年 | 1735篇 |
1971年 | 1466篇 |
1970年 | 1528篇 |
1969年 | 1472篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
Heimann M Beco L Petein M Nishifuji K Amagai M Olivry T Olivry DT 《Veterinary pathology》2007,44(4):550-555
Pemphigus vegetans is a rare autoimmune blistering acantholytic dermatosis of humans that combines unusually hyperplastic and verrucous pustular skin lesions and mucosal erosions. We report herein the clinical, histopathologic, and immunologic findings in a dog whose lesions resembled, but were not identical to, those of human pemphigus vegetans. A 4-year-old male Greater Swiss Mountain Dog presented with multifocal cutaneous verrucous and crusted papules and pustules, as well as skin and mucosal erosions and ulcers. Microscopic lesions consisted of exophytic papillated epidermal hyperplasia, superficial and deep intraepidermal acantholytic neutrophilic and eosinophilic pustules, and suprabasal epidermal clefts leaving rounded basal keratinocytes at the bottom of the vesicles. Direct and indirect immunofluorescence revealed antikeratinocyte IgG autoantibodies. Immunoprecipitation immunoblotting and immunoabsorption experiments with recombinant canine desmogleins confirmed that autoantibodies recognized desmoglein-1. In this dog, clinical and histopathologic features resembled those of human pemphigus vegetans, while circulating autoantibodies against canine desmoglein-1 were solely identified. This antigen target is different from that of the human disease in which antidesmoglein-3 autoantibodies are detected most commonly. 相似文献
942.
Christopher J Bonar Ernesto O Boede Manuel García Hartmann Joanne Lowenstein-Whaley Esmeralda Mujica-Jorquera Scott V Parish James V Parish Michael M Garner Cynthia K Stadler 《Journal of zoo and wildlife medicine》2007,38(2):177-191
River dolphins are especially susceptible to negative human impacts. For their conservation, attempts of relocation or procreation ex situ may become important in the future to avoid their extinction. Additional knowledge and medical experiences of river dolphin management in captivity may aid such conservation efforts. The medical records and necropsy and histopathology reports on 123 captive Amazon River dolphins (Inia geoffrensis) were re-viewed. Of these 123 animals, 105 were necropsied and 70 necropsies were supported with histopathology. Eighteen animals were not necropsied. Among wild-born animals, mortality was highest in the first 2 mo immediately postcapture and transport, accounting for 32 of 123 deaths. Pneumonia and skin lesions (cutaneous and subcutaneous ulcerations and abscesses) were the most common findings, found in 44 of 105 (42%) and 38 of 105 (36%) of gross diagnoses, respectively. At least 10 of 44 cases of pneumonia diagnosed grossly included a verminous component. Cachexia, from a variety of causes, was a major gross finding in 21 animals. Fifteen animals had histologic evidence of significant renal pathology, and this was the primary cause of death in 13 cases. Hepatic pathology was found in 18 cases, and bacterial sepsis was confirmed via histology in 16 cases. Based on these findings, it may be concluded that keys to successful maintenance of this species include 1) prophylactic anthelminthic and antibiotic therapy immediately post-capture; 2) maintenance of animals in larger enclosures than in past attempts, in compatible groups, and in facilities capable of separating aggressive animals; 3) maintenance in microbiologically hygienic water quality at all times; and 4) a proactive program of preventive medicine during the immediate postcapture, quarantine, and maintenance period of captivity. 相似文献
943.
The California Milk Cell Test (CMCT) and somatic cell counts (SCC) on their own were not reliable methods in the identification of subclinical mastitis in the dairy goats studied and should be accompanied by microbiological tests. However, CMCT and SCC were indicators of irritation of the udder parenchyma. In healthy goats Spectrazol Milking Cow (Schering-Plough AH) caused the least and Curaclox LC (Norbrook (ARK AH)) the most irritation of parenchyma after intramammary treatment. The effects of Rilexine 200 LC (Logos Agvet (Virbac)) were intermediate. There was a highly significant difference (P < 0.001) in the mean log SCC between treated and control groups for goats treated with Curaclox LC and Rilexine 200 LC but no significant difference was present in the mean log SCC of treatment and control groups for goats treated with Spectrazol Milking Cow at the 07:00 and at 19:00 samplings. The CMCT was an indicator of the level of SCC in goat milk. The CMCT was more useful in confirming the absence of infection, rather than in diagnosing mastitis. 相似文献
944.
W.M. Muir 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2007,124(6):342-355
Accuracy of prediction of estimated breeding values based on genome-wide markers (GEBV) and selection based on GEBV as compared with traditional Best Linear Unbiased Prediction (BLUP) was examined for a number of alternatives, including low heritability, number of generations of training, marker density, initial distributions, and effective population size (Ne). Results show that the more the generations of data in which both genotypes and phenotypes were collected, termed training generations (TG), the better the accuracy and persistency of accuracy based on GEBV. GEBV excelled for traits of low heritability regardless of initial equilibrium conditions, as opposed to traditional marker-assisted selection, which is not useful for traits of low heritability. Effective population size is critical for populations starting in Hardy-Weinberg equilibrium but not for populations started from mutation-drift equilibrium. In comparison with traditional BLUP, GEBV can exceed the accuracy of BLUP provided enough TG are included. Unfortunately selection rapidly reduces the accuracy of GEBV. In all cases examined, classic BLUP selection exceeds what was possible for GEBV selection. Even still, GEBV could have an advantage over traditional BLUP in cases such as sex-limited traits, traits that are expensive to measure, or can only be measured on relatives. A combined approach, utilizing a mixed model with a second random effect to account for quantitative trait loci in linkage equilibrium (the polygenic effect) was suggested as a way to capitalize on both methodologies. 相似文献
945.
946.
Galuppi R. Avenoso A.M. Leotti G. Ostanello F. Poglayen G. Tampieri M. P. 《Veterinary research communications》2007,31(1):233-236
Veterinary Research Communications - Galuppi, R., Avenoso, A.M., Leotti, G., Ostanello, F., Poglayen, G. and Tampieri, M.P., 2007. Diagnosis of sarcoptic mange in slaughtered swine. Veterinary... 相似文献
947.
Synovial hemangioma was diagnosed in an 8-year-old castrated male Belgian Sheepdog with lameness of 3 months' duration. Pain, soft-tissue swelling, and hemarthrosis were localized to the left stifle joint. Projections of synovial membrane with reddish-purple nodules, excised via arthrotomy, were composed histologically of variably sized vascular channels that were lined by well-differentiated endothelial cells and separated by fibrous septa. Distension of some channels resulted in endothelial disruption, thrombosis, hemorrhage, necrosis, and focal spindle-cell proliferation. The limb was amputated to remove remaining neoplastic tissue. The hemangioma extended focally into the joint capsule and popliteal soft tissue but did not invade skeletal muscle or bone. The dog was free of detectable neoplasia 6 months after amputation. Synovial hemangioma is a rare benign vascular proliferation in people, most commonly in the knee, and should be included in the differential diagnosis for canine synovial tumors. 相似文献
948.
E J van der Molen J H van Lieshout M J Nabuurs F H Derkx A P Lamers A M Michelakis 《Research in veterinary science》1989,46(3):401-405
Carbadox is known to induce toxic effects on the adrenal cortex, resulting in hypoaldosteronism. To study the involvement of carbadox on the renin-angiotensin system, weaned piglets of five weeks old received feed supplemented with 0 (control group), 50, 100, 150 or 200 ppm carbadox. After four weeks the 100 and 150 ppm groups had significantly higher plasma renin activity levels than the control group and after nine weeks plasma renin activity levels of all treated groups were significantly higher than the control group. Five and 10 weeks after carbadox administration, three and two pigs, respectively, of all groups were necropsied and the kidneys were screened for immunohistochemically demonstrated renin. All dosed pigs demonstrated an increase of immunoreactive renin, which was dose- and time-related. From these results it is concluded that carbadox induces activation of the renin-angiotensin system, secondary to the suppressing effect on mineralocorticoid secretion and that these changes may be responsible for part of the clinical picture. 相似文献
949.
J N Nielsen C H Armstrong J J Turek N C Nielsen 《Journal of veterinary diagnostic investigation》1989,1(2):160-164
One hundred thirty-eight swine abortions were studied in detail in an effort to identify an etiologic agent. A viral agent was implicated in 7 cases. Bacteria were isolated in less than half of the examined cases: however, in 61% of the cases, motile, filamentous organisms were observed in tissues and fluids. Although swine sera from farms experiencing reproductive problems had a high reactor rate to Leptospira bratislava antigen, electron microscopy of the observed organism revealed a wall-free prokaryote morphologically typical of the class Mollicutes. 相似文献
950.
J C Lewis A J Fitzgerald F M Gulland C M Hawkey P Kertesz J K Kirkwood R A Kock 《The British veterinary journal》1989,145(4):394-396
Clinical experience of 73 cases of necrobacillosis in red-necked wallabies (Macropus rufogriseus) over a 6-year period is reviewed. Diagnostic methods and the medical and surgical treatment options are detailed. It is suggested that survival curves are necessary to assess the outcome of treatment. 相似文献