全文获取类型
收费全文 | 9205篇 |
免费 | 695篇 |
国内免费 | 3篇 |
专业分类
林业 | 834篇 |
农学 | 358篇 |
基础科学 | 58篇 |
2529篇 | |
综合类 | 247篇 |
农作物 | 453篇 |
水产渔业 | 945篇 |
畜牧兽医 | 3528篇 |
园艺 | 135篇 |
植物保护 | 816篇 |
出版年
2023年 | 76篇 |
2022年 | 111篇 |
2021年 | 227篇 |
2020年 | 212篇 |
2019年 | 146篇 |
2018年 | 466篇 |
2017年 | 464篇 |
2016年 | 459篇 |
2015年 | 360篇 |
2014年 | 400篇 |
2013年 | 608篇 |
2012年 | 726篇 |
2011年 | 640篇 |
2010年 | 379篇 |
2009年 | 299篇 |
2008年 | 525篇 |
2007年 | 532篇 |
2006年 | 427篇 |
2005年 | 426篇 |
2004年 | 367篇 |
2003年 | 323篇 |
2002年 | 266篇 |
2001年 | 198篇 |
2000年 | 200篇 |
1999年 | 171篇 |
1998年 | 30篇 |
1997年 | 35篇 |
1996年 | 27篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 17篇 |
1992年 | 56篇 |
1991年 | 40篇 |
1990年 | 40篇 |
1989年 | 47篇 |
1988年 | 36篇 |
1987年 | 40篇 |
1986年 | 46篇 |
1985年 | 47篇 |
1984年 | 35篇 |
1983年 | 34篇 |
1982年 | 19篇 |
1981年 | 14篇 |
1979年 | 31篇 |
1978年 | 30篇 |
1977年 | 27篇 |
1974年 | 26篇 |
1973年 | 45篇 |
1972年 | 30篇 |
1971年 | 25篇 |
排序方式: 共有9903条查询结果,搜索用时 31 毫秒
991.
The prevalence of Cryptosporidium, Giardia, and Enterocytozoon bieneusi in cats from Bogota (Colombia) was determined from fecal specimens and scrapings of duodenal and ileal mucosa screened by PCR. All PCR-positive specimens were sequenced to determine the genotype(s) present. Of 46 cats, 6 (13%) were positive for Cryptosporidium, 5 (11%) were infected with C. felis and one (2%) with C. muris. Three (6.5%) cats were infected with Giardia duodenalis Assemblage F. Eight (17%) cats were infected with four genotypes of E. bieneusi: genotype D-like (9%), K (4%), Peru 10 (2%), and Peru 5 (2%). This is the first report on the presence of zoonotic species/genotypes of Cryptosporidium and E. bieneusi in cats in Colombia. 相似文献
992.
García AT 《Veterinary parasitology》2006,138(1-2):97-102
Babesiosis is a world-wide zoonosis caused by tick-borne hematozoan parasites of the genus Babesia. Canine Babesidae have historically been classified as "large Babesia" (Babesia canis) and "small Babesia" (Babesia gibsoni) based on the size of their intraerythrocytic forms. Genetic sequencing technology using the polymerase chain reaction (PCR) has allowed further subdivision. B. gibsoni has three strains: "Asia", "California" and a recently identified small babesial-like parasite, Theileria annae. This newly recognised piroplasm appears to be hyperendemic in northwest Spain. In order to provide some insight into the situation, all the cases diagnosed in our laboratory (NW of Spain) during 2003 were evaluated. Our study (62 samples) shows the existence of a piroplasm morphologically different from B. canis and similar to B. gibsoni, which is genetically related to T. annae. Severe regenerative anemia and thrombocytopenia are almost constant characteristics of infection with T. annae in dogs. In many cases azotemia is found. Abnormally high serum concentrations of urea and creatinin, together with elevated concentrations of inorganic phosphorus, hypoalbuminemia, hypercholesterolemia, proteinuria, high protein/creatinin and presence of hyaline and granular casts in the microscopic examination of urine sediment suggest a glomerular component to the disease. We conclude that observational research and clinical trials should be conducted in order to improve our understanding of this emerging disease in order to provide some insight into the best therapeutic practices. 相似文献
993.
Cysticercosis is due to the establishment of the larval stage of the zoonotic cestode parasite Taenia solium. The infection causes substantial human morbidity and mortality, particularly in several Latin American countries and parts of Africa and Asia, as well as economic losses in pig husban dry due to condemnation of infected pork meat. The life cycle of T. solium includes human beings as definitive hosts and pigs as intermediate hosts. Cysticercosis is acquired by the ingestion of eggs released by human tapeworm carriers, who become infected after ingesting pork meat contaminated with cysticerci. Taenia solium transmission has been associated with poverty, lack of sanitary services and practices of rearing backyard pigs with free access to the areas that villagers use as toilets, as well as cultural behaviour. Nonetheless, due to the recent increase of migration and tourism, industrial countries are also reporting cases of human cysticercosis. There are many epidemiological studies that have been conducted mainly in Latin American countries that have evaluated intervention measures for control of cysticercosis including the development and testing of vaccines. Furthermore, the involvement of international agencies and institutions, such as the World Health Organization, the Food and Agriculture Organization and the International Livestock Research Institute, as well as the commitment of policymakers, scientists and field workers, are key means for the sustainable control and, hopefully, eradication of T. solium infections. 相似文献
994.
Vecerek V 《Journal of veterinary medical education》2006,33(2):197-205
This article describes the two separate programs of veterinary education offered at the University of Veterinary and Pharmaceutical Sciences in Brno, Czech Republic, which are directed to clinical veterinary medicine and to veterinary food safety, hygiene, and ecology, respectively. Both programs provide a level of training such that all graduates are competent for veterinary practice in any area of veterinary medicine; however, each offers an extended and deepened emphasis of training in clinical medicine, on the one hand, and food safety, on the other. A key feature is that the cohort of students for each program enters having pre-selected a career in one of these two areas. One of the important end results of this structure is that it fulfills the growing and important mission of providing a critical number of veterinarians in food safety and all of its allied fields. 相似文献
995.
del Río ML Navas J Martín AJ Gutiérrez CB Rodríguez-Barbosa JI Rodríguez Ferri EF 《Veterinary research》2006,37(1):49-59
Bacteria have evolved a set of highly specialized proteins to capture iron in iron-depleted environments. The acquisition and uptake of iron present in the extracellular milieu of eukaryotic organisms is indispensable for the growth and survival of microbial pathogens in the course of infection. Haemophilus parasuis is the causative agent of Gl?sser disease, which is responsible for considerable financial losses in pig-rearing worldwide. To gain insight into the mechanisms involved in siderophore-mediated iron uptake in H. parasuis, genes in the H. parasuis ferric hydroxamate uptake (Fhu) region were amplified in the work being reported here. As has been described in A. pleuropneumoniae, an Fhu genomic region was also present in H. parasuis, being composed of four potential consecutive open reading frames (ORF) designated as fhuC, fhuD, fhuB, and fhuA, respectively. By immunoblotting, using a cross-reactive polyclonal antibody raised against Actinobacillus pleuropneumoniae FhuA protein, it was demonstrated that this protein was constitutively expressed in H. parasuis and its level of expression was not modified under conditions of restricted iron availability. This is the first report describing the presence of the fhu genes in H. parasuis. Our results indicate that FhuA protein expression is not affected under iron-restricted conditions, however, it is one of the targets of the humoral immune response. 相似文献
996.
Ruiz A González JF Rodríguez E Martín S Hernández YI Almeida R Molina JM 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2006,53(8):399-402
A survey of Eimeria infections was performed in dairy goats and kids (<6 months old) of six farms from a dry desert area of Gran Canaria Island (Spain). The number of oocysts per gram of faeces (OPG) was determined by a modified McMaster technique over a total of 2,616 individual faecal samples taken from the rectum in monthly intervals. Eimeria oocysts were found in 96.1% of the samples with OPG ranging from 1 x 10(2) to 1.4 x 10(6). Kid goats had significantly (P < 0.001) higher OPG counts (46,496 +/- 5,228) than dairy females (2,225 +/- 287). Eight Eimeria species were identified, with Eimeria ninakohlyakimovae (30.0%), Eimeria arloingi (28.6%) and Eimeria alijevi (20.5%) being the most frequent species followed by Eimeria caprina (9.1%), Eimeria christenseni (4.5%), Eimeria jolchijevi (3.4%), Eimeria caprovina (3.2%) and Eimeria hirci (0.7%). Although significant differences were observed among goat groups and herds, the eight species were present in the six farms in both dairy goats and kids. The intensity of oocysts shedding was related to some factors such as the size of the herd and was further influenced by the prevailing climatic conditions of the area. The highest OPG counts were recorded during the hot season in dairy goats and close to weaning time in kids reared in small farms having no prophylactic treatments against eimeriosis. 相似文献
997.
Gómez-Villamandos RJ Domínguez JM Redondo JI Martín EM Granados MM Ruiz I Santisteban JM 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2006,53(9):471-475
The objective of this paper was to evaluate romifidine as a pre-medicant in dogs prior to propofol-isoflurane anaesthesia, and to compare it with medetomidine. For this, eight healthy dogs were anaesthetised. Each dog received three pre-anaesthetic protocols: R40 (romifidine, 40 microg/kg, IV), R80 (romifidine, 80 microg/kg, IV) or MED (medetomidine, 10 microg/kg, IV). Induction of anaesthesia was delivered with propofol and maintained with isoflurane. The following variables were studied before sedative administration and 10 min after sedative administration: heart rate (HR), mean arterial pressure (MAP), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) and respiratory rate (RR). During maintenance, the following variables were recorded at 5-min intervals: HR, MAP, SAD, DAP, arterial oxygen saturation (SpO(2)), end-tidal CO(2)(EtCO(2)), end-tidal concentration of isoflurane (EtISO) required for maintenance of anaesthesia and tidal volume (TV). Time to extubation, time to sternal recumbency and time to standing were also registered. HR and RR experimented a significantly decreased during sedation in all protocols respect to baseline values. Mean HR, MAP, SAP, DAP, SpO(2), EtCO(2), and TV during anaesthesia were similar for the three protocols. End tidal of isoflurane concentration was statistically similar for all protocols. Recovery time for R40 was significantly shorter than in R80 and MED. The studied combination of romifidine, propofol and isoflurane appears to be an effective drug combination for inducing and maintaining general anaesthesia in healthy dogs. 相似文献
998.
Cárceles CM Serrano JM Marín P Escudero E Fernández-Varón E 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2006,53(6):300-304
The pharmacokinetics (PK) of moxifloxacin in healthy white New Zealand rabbits was studied following intravenous (IV) and subcutaneous (SC) administration routes as well as a SC long-acting poloxamer 407 gel formulation (SC-P407). Moxifloxacin concentrations were determined by high-performance liquid chromatography assay with fluorescence detection. Mean half-life for IV, SC and SC-P407 routes was 2.15, 5.41 and 11.09 h. Clearance value after IV dosing was 0.78 l/kg/h. After SC administration, the mean absolute bioavailability was 117% and the C(max) was 1.61 +/- 0.49 mg/l. After SC-P407 administration, the bioavailability was 44% and the C(max) 1.83 was +/-0.62 mg/l. No adverse effects were observed in any of the rabbits following IV, SC and SC-P407 administration of moxifloxacin. Minimal inhibitory concentrations of moxifloxacin against different strains of Staphylococcus aureus from different european countries were used to compute the main pharmacodynamic (PD) surrogate markers of efficacy. The high tolerability of this SC-P407 formulation and the favourable PK behaviour such as the long half-life, acceptable bioavailability and excellent PK-PD ratios achieved indicate that it is likely to be effective in rabbits. 相似文献
999.
García-Fernández RA Pérez-Martínez C Alvarez JE Navarrete AJ García-Iglesias MJ 《Veterinary dermatology》2006,17(1):36-44
Epidermal morphogenesis was studied in vivo following prenatal exposure to retinoic acid (RA). In pregnant mice, a single oral dose of RA on day 11.5 of gestation failed to induce histological changes in fetal epidermal development except in epidermal thickness. Epidermal thickness increased from 16.5 days post-coitum (dpc) onwards, and temporal and spatial epidermal modifications in keratins K5 and K14 related to proliferative activity of keratinocytes were observed. An RA effect on cell proliferation was supported by a statistically significant increase in the number of epidermal S-phase cells, containing BrdU-incorporated DNA in RA-exposed mice compared with nonexposed animals. The prolonged in utero action of RA on epidermal proliferative activity in fetuses and newborns suggests a long-term RA effect that may play a role on the development and evolution of diseases in adult skin. 相似文献
1000.
Brazís P Barandica L García F Clough GF Church MK Puigdemont A 《Veterinary dermatology》2006,17(3):169-174
Dermal microdialysis, a relatively noninvasive technique, allows investigation of the changes in cellular mediators released during cutaneous allergic responses. This technique was used to evaluate the effect of cyclosporin A, an immunosuppressive drug used for treatment of canine atopic dermatitis, on the cutaneous release of two pro-inflammatory mediators following intradermal allergen challenge. Four beagle dogs spontaneously sensitized to Ascaris suum were treated for 1 month with oral cyclosporin A. At days 0, 15 and 30 of the treatment, dialysis probes were inserted into the skin of the back, and 20 microL of A. suum antigen was injected intradermally at each site. At timed intervals, dialysate was collected and assayed for histamine and prostaglandin D(2) and the wheal area was measured. Mean histamine concentration and wheal area were significantly lower at days 15 and 30 of treatment, compared with day 0. However, prostaglandin D(2) concentration was not significantly reduced. The inhibition in histamine release after intradermal challenge, by cyclosporin, confirms its anti-inflammatory action in the dog. Dermal microdialysis provides a useful tool for investigating canine allergic reactions and their modulation by drugs. 相似文献