全文获取类型
收费全文 | 25701篇 |
免费 | 233篇 |
国内免费 | 163篇 |
专业分类
林业 | 1035篇 |
农学 | 233篇 |
基础科学 | 84篇 |
3580篇 | |
综合类 | 5864篇 |
农作物 | 829篇 |
水产渔业 | 221篇 |
畜牧兽医 | 13323篇 |
园艺 | 141篇 |
植物保护 | 787篇 |
出版年
2016年 | 43篇 |
2015年 | 52篇 |
2014年 | 64篇 |
2013年 | 60篇 |
2012年 | 2167篇 |
2011年 | 2478篇 |
2010年 | 515篇 |
2009年 | 361篇 |
2008年 | 2123篇 |
2007年 | 2177篇 |
2006年 | 1927篇 |
2005年 | 1923篇 |
2004年 | 1794篇 |
2003年 | 1643篇 |
2002年 | 1509篇 |
2001年 | 1013篇 |
2000年 | 1293篇 |
1999年 | 501篇 |
1998年 | 94篇 |
1997年 | 80篇 |
1996年 | 105篇 |
1995年 | 154篇 |
1994年 | 152篇 |
1993年 | 156篇 |
1992年 | 181篇 |
1991年 | 197篇 |
1990年 | 198篇 |
1989年 | 162篇 |
1988年 | 183篇 |
1987年 | 193篇 |
1986年 | 156篇 |
1985年 | 128篇 |
1984年 | 165篇 |
1983年 | 144篇 |
1982年 | 115篇 |
1981年 | 84篇 |
1980年 | 77篇 |
1979年 | 76篇 |
1978年 | 37篇 |
1976年 | 46篇 |
1974年 | 43篇 |
1973年 | 35篇 |
1970年 | 40篇 |
1963年 | 69篇 |
1960年 | 40篇 |
1959年 | 44篇 |
1958年 | 44篇 |
1957年 | 69篇 |
1954年 | 40篇 |
1953年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
991.
992.
Szmollény G Kostyák A Kovács S Speed K Jones Y László VG Gadó I Pászti J Wray C Nagy B 《Acta veterinaria Hungarica》2000,48(4):407-420
Reports on the internationally emerging significance of multiresistant zoonotic Salmonella in animals and man prompted studies to estimate the significance of multiresistant Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) phage type DT104 of animal origin in Hungary. A collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrofloxacin, nalidixic acid, streptomycin, tetracycline and sulphamethoxazole). Strains with resistance against 3 or more were defined as multiresistant. All strains were phage typed using Felix-Callow's S. Typhimurium phage typing system, and 91 of them (suspect DT104) were also typed according to Anderson's definitive typing (DT) system. In this study, 14% of animal strains from 1997-1998 was classified as DT104, for which turkey, pig and duck seemed to be the main carriers, and the multiresistant non-DT104 strains represented a further 6% of this collection. The prevalence of DT104 was highest among strains of turkey origin (50%), followed by strains of pig (29%), chicken (25%), duck (19%), and goose (3%) origin. The other DT104 related phage types (DT12 and U302) were only detected in the case of 4 strains (2 of porcine, and one each of turkey and of goose origin). The DT104 corresponded to the Felix-Callow types 2/3 or 2c/3 in each case, except in the case of 3 turkey strains where they corresponded to type 35/3. Nalidixic acid resistance was detected in all multiresistant turkey strains and in some of other animal origin but none of these strains were resistant to enrofloxacin. A retrospective analysis (based on the above relationship) indicated that S. Typhimurium strains corresponding to DT104 could be present and increase in the Hungarian farm animal population from about 2% to 20% between 1985 and 1990, in a manner similar to the emergence of human DT104, as reported elsewhere (Pászti et al., 2000). The 91 suspect DT104 strains were also tested for plasmid profile and for spvC gene indicating the presence of the large serotype specific plasmid (Ssp). No characteristic plasmid profile could be attributed to S. Typhimurium DT104. The serovar-specific large plasmid was detected by PCR for spvC in 100% of DT104 strains and in 77% of the non-DT104 strains. The virulence of two DT104 strains was tested in orally infected day-old chicks and compared with virulence of 4 non-DT104 strains. Higher colonizing virulence of DT104 strains could be established as compared to the other strains. 相似文献
993.
Drén CN Kant A Van Roozelaar DJ Hartog L Noteborn MH Koch G 《Acta veterinaria Hungarica》2000,48(4):455-467
The pathogenesis of chicken infectious anaemia virus (CAV) infection was studied in 6-week-old and one-day-old SPF chickens inoculated intramuscularly with graded doses of Cux-1 strain (10(6)-10(2) TCID50/chicken). Viraemia, virus shedding, development of virus neutralizing (VN) antibodies and CAV distribution in the thymus were studied by virus isolation, polymerase chain reaction (PCR), immunocytochemistry (IP) and in situ hybridization until postinfection day (PID) 28. In 6-week-old chickens infected with high doses of CAV, viraemia and VN antibodies could be detected 4 PID and onward without virus shedding or contact transmission to sentinel birds. However, virus shedding and contact transmission were demonstrated in one-day-old infected chickens. In the 6-week-old groups infected with lower doses, VN antibodies developed by PID 14, transient viraemia and virus shedding were detected. The thymus cortex of all 1-day-old inoculated chickens stained with VP3-specific mAb. Cells with positive in situ hybridization signal were fewer and scattered throughout the thymus tissue of the one-day-old inoculated chickens as compared to IP-positive cells. These results suggest that early immune response induced by high doses of CAV in 6-week-old chickens curtails viral replication and prevents virus shedding. 相似文献
994.
Pástorová B Staníková A Molnárová M Halagan J Buleca J 《Acta veterinaria Hungarica》2000,48(1):107-111
The influence of hormonal superovulatory preparations Folistiman (450 IU FSH, Spofa, Prague) and serum gonadotropin (1500 IU PMSG, Spofa, Prague) on monoamine oxidase (MAO), the degradative enzyme of catecholamines, was investigated in some areas of the brain regulating reproductive functions (area preoptica of the hypothalamus, pituitary gland, and pineal gland) in ewes with synchronized oestrus (20 mg chlorsuperlutin) during the oestrous period using a radiochemical method. After intramuscular administration of 1500 IU PMSG, marked increase of MAO activity was found in the area preoptica (p < 0.05) and in the pituitary gland (p < 0.01) in comparison with the control group. No change occurred in MAO activity after ovarian stimulation with FSH. Administration of the above superovulatory preparations failed to induce MAO activity in the pineal gland of sheep. 相似文献
995.
996.
From 1992 to 1995, 0.15% (n=3916) of the bovids (cattle and buffalo) in Sri Lanka were sampled, using a multi-stage sampling procedure. Serum antibodies for Brucella abortus were detected using the indirect enzyme-linked immunosorbent assay (ELISA). The age, the agroecological zone and the management system practiced in the farms of the sampled bovids were studied as risk factors for seropositivity.The overall seroprevalence of brucellosis in cattle was 4.7% (n=3076) and 4.2% in buffaloes (n=840). Bovids that were over 3 years of age, from the dry zone (annual rainfall 20-35 in.), and reared under an extensive management system had higher odds of being seropositive. Bovids from the dry zone were at approximately six times higher odds of being seropositive even after controlling for the possible effects of age and management system. Approximately 75% of the seropositive males were from the dry zone. Most bovids (84%) from the dry zone in this study were reared under an extensive management system (free grazing) which allows unrestricted contact between animals. These factors may have contributed to the spread of brucellosis in bovids in the dry zone.This infection might be an important cause of abortion in bovids in Sri Lanka. However, there is also evidence of other causes for abortion, repeat breeding and retained placenta. 相似文献
997.
A mailed questionnaire survey was done to study dog-owners' knowledge of canine inherited diseases and the present screening and control programs in Finland, as well as to study the importance of health-related matters and well-being to dog-owners. The purpose was also to study the owners' role in programs and the influence of health and well-being in their decision-making process and choices when purchasing a puppy. This study showed that dog-owners highly valued health-related matters and well-being. The present programs were considered to have a positive effect on the prevention of canine inherited diseases. Dog-owners estimated that their own knowledge could be better but they believed in veterinarians' and dog-breeders' ability to inform them. Inherited skeletal and ocular diseases were thought to be important to canine well-being; the importance of other diseases or behaviour problems was assessed to be lower. In choosing a suitable breed, behaviour and temperament were the most-important factors but health-related matters were essential in actually choosing a puppy's breeder and the litter. Well-being and health were also considered very important to the image of the dog hobby. 相似文献
998.
The effect was studied of an acute and non-persistent hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples. Five dogs were given glucose solution intravenously and blood samples were taken from each dog before and at 5, 15, 30, 60 and 120 min and 24 h after the infusion. There was an intense hyperglycaemia 5 min after the injection was given, but no statistically significant differences in the serum fructosamine and glycated haemoglobin were observed. It was concluded that an acute and transient hyperglycaemia does not cause significant changes in the glycated haemoglobin and fructosamine concentrations in healthy dogs. 相似文献
999.
Makrai L Fodor L Csivincsik A Varga J Senoner Z Szabó B 《Acta veterinaria Hungarica》2000,48(3):253-259
The cultural, morphological, biochemical, serological characteristics and antibiotic susceptibility of 25 Rhodococcus equi strains isolated from lungs and lung abscesses of pneumonic foals and 5 R. equi strains isolated from immuno-compromised human patients were examined. All R. equi strains showed common cultural, morphological and biochemical characteristics both with conventional tests and on the basis of their enzyme profile. The R. equi strains examined were resistant to penicillins with the exception of ampicillin, to sulphamethazine and several strains also to sulphamethoxazole-trimethoprim. All strains were susceptible to erythromycin and rifampicin. The strains isolated from humans showed somewhat higher rate of antibiotic resistance to penicillin, cefotaxime, kanamycin, streptomycin, lincomycin, and oxytetracycline. The overwhelming majority (96%) of the equine isolates belonged to serotype 1 in Prescott's serotyping system, while the human isolates could not be serotyped. 相似文献
1000.
Eighty-three canine cutaneous mast cell tumors were graded histologically and evaluated immunohistochemically for p53 tumor-suppressor protein expression. An avidin-biotin immunohistochemical protocol incorporated a rabbit polyclonal antibody (CM-1) directed against normal and mutant p53 protein. Positive staining was observed in 44.6% (37/83) of tumors and included 50% (12/24) of grade I (well differentiated) tumors, 46.9% (23/49) of grade II (intermediate differentiation) tumors, and 20% (2/10) of grade III (poorly differentiated) tumors. A statistically significantly higher proportion (P < 0.019) of tumors from the head and neck (83.3%, 10/12), stained positive for p53 than tumors from the thorax, back, abdomen, and axilla (39.4%, 13/33), legs (35.7%, 10/28), or prepuce, scrotal, or inguinal areas (44.4%, 4/9). No statistically significant difference between p53 labeling and histologic grade, breed, or tumor size was present. Survival data were available for 53/83 (63.9%) of dogs. Positive reactivity for p53 was observed in 47% (25/53) of tumors within this group, with 57.9% (11/19) of grade I, 43.3% (13/30) of grade II, and 25% (1/4) of grade III tumors labeled. Mean survival time for the 53 dogs was 12.1 months. The median survival time for dogs with grade III tumors or tumors >5 cm was statistically significantly shorter (P < 0.0001) than for dogs with grades I and II or smaller tumors. Although p53 protein abnormalities may play a role in tumor development or behavior in some canine cutaneous mast cell tumors, immunoreactivity was not associated with lack of tumor differentiation, tumor locations previously shown to demonstrate aggressive biological behavior, breed predisposition, or survival times. 相似文献