全文获取类型
收费全文 | 129808篇 |
免费 | 7589篇 |
国内免费 | 804篇 |
专业分类
林业 | 5272篇 |
农学 | 4015篇 |
基础科学 | 918篇 |
15176篇 | |
综合类 | 24716篇 |
农作物 | 4678篇 |
水产渔业 | 6005篇 |
畜牧兽医 | 67843篇 |
园艺 | 1726篇 |
植物保护 | 7852篇 |
出版年
2019年 | 1346篇 |
2018年 | 1999篇 |
2017年 | 2207篇 |
2016年 | 1987篇 |
2015年 | 1879篇 |
2014年 | 2112篇 |
2013年 | 5013篇 |
2012年 | 4064篇 |
2011年 | 4942篇 |
2010年 | 3250篇 |
2009年 | 3133篇 |
2008年 | 4485篇 |
2007年 | 4358篇 |
2006年 | 4002篇 |
2005年 | 3756篇 |
2004年 | 3440篇 |
2003年 | 3538篇 |
2002年 | 3351篇 |
2001年 | 3820篇 |
2000年 | 3858篇 |
1999年 | 3031篇 |
1998年 | 1283篇 |
1997年 | 1190篇 |
1995年 | 1263篇 |
1994年 | 1148篇 |
1993年 | 1136篇 |
1992年 | 2478篇 |
1991年 | 2775篇 |
1990年 | 2609篇 |
1989年 | 2586篇 |
1988年 | 2410篇 |
1987年 | 2412篇 |
1986年 | 2489篇 |
1985年 | 2349篇 |
1984年 | 1978篇 |
1983年 | 1741篇 |
1982年 | 1167篇 |
1979年 | 1794篇 |
1978年 | 1423篇 |
1977年 | 1273篇 |
1976年 | 1306篇 |
1975年 | 1367篇 |
1974年 | 1694篇 |
1973年 | 1688篇 |
1972年 | 1625篇 |
1971年 | 1493篇 |
1970年 | 1501篇 |
1969年 | 1420篇 |
1968年 | 1209篇 |
1967年 | 1255篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Evaluation of iodophor skin preparation techniques and factors influencing drainage from ventral midline incisions in horses. 总被引:1,自引:0,他引:1
L D Galuppo J R Pascoe S S Jang N H Willits S L Greenman 《Journal of the American Veterinary Medical Association》1999,215(7):963-969
OBJECTIVE: To document natural bacterial flora on the ventral aspect of the equine abdomen, to compare 2 preparation techniques, and to identify potential risk factors that may contribute to incisional drainage. DESIGN: Prospective study. ANIMALS: 53 horses undergoing exploratory celiotomy. PROCEDURE: Group-1 horses (n = 26) were prepared with povidone-iodine and alcohol. Group-2 horses (27) were prepared with a film-forming iodophor complex. Numbers of bacterial colony-forming units (CFU) were measured before and after surgical scrub, following skin closure, and after recovery from general anesthesia. Swab specimens to identify normal skin bacterial flora and potential pathogens were obtained by swabbing a 4 x 4-cm area. Variables that might affect incisional drainage were also investigated. RESULTS: For both techniques, there was a significant reduction in bacterial numbers after skin preparation. Incisional drainage was observed in 14 (26%) horses (8 group-1 and 6 group-2 horses). Preexisting dermatitis, poor intraoperative drape adherence, high number of bacterial CFU obtained after recovery from anesthesia, and high number of CFU obtained from the surgery room environment were the main risk factors associated with subsequent incisional drainage. Bacillus spp, nonhemolytic Staphylococcus spp, Micrococcus spp, Corynebacterium spp, Streptomyces spp, other nonenteric genera, and nonhemolytic Streptococcus spp were the most common isolates obtained before surgical scrub. CONCLUSIONS AND CLINICAL RELEVANCE: Both skin preparation techniques were equally effective in reducing numbers of bacterial CFU by 99%, and a significant difference was not found in incisional drainage rate between groups. Protection of the wound during recovery from anesthesia and the immediate postoperative period may reduce incisional drainage after abdominal surgery in horses. 相似文献
992.
993.
F D Bastida-Corcuera K H Nielsen L B Corbeil 《Veterinary immunology and immunopathology》1999,71(2):143-149
Immunoglobulin binding proteins (IgBPs) are thought to be virulence factors which enable pathogens to evade the host's immune response. Since bovine IgG2 is important in protection against pyogenic infections, the binding characteristics of Staphylococcus aureus protein A (PrA), streptococcal protein G (PrG), or Haemophilus somnus high molecular weight IgBPs to the two bovine IgG2 allotypes were examined. For PrA or PrG binding of IgG2, guinea pig red blood cells coated with specific IgG2a or IgG2b antibodies were used in a competitive binding inhibition assay with unlabeled and horseradish peroxidase-labeled PrA or PrG. To determine which sizes of H. somnus. IgBPs bind to the two IgG2 allotypes, immunoblots with H. somnus culture supernatant were probed with anti-DNP IgG2a and IgG2b. This detects only Fc binding because anti-DNP does not cross-react with H. somnus antigens. Both IgG2 allotypes bound equally well to PrA and PrG. However, IgG2b but not IgG2a bound to H. somnus high molecular weight IgBPs. The lack of differential binding of bovine IgG2 allotypes to PrA and PrG means that these IgBPs can be considered to be unbiased reagents in assays for detection of bovine IgG2 or for immunoaffinity purification. The differential binding of H. somnus IgBPs to the IgG2 allotypes indicates that animals having one allotype may be more resistant to H. somnus infection than animals having the other allotype. 相似文献
994.
Steiss J Braund K Wright J Lenz S Hudson J Brawner W Hathcock J Purohit R Bell L Horne R 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1999,13(6):540-548
A condition colloquially referred to as "limber tail" and "cold tail" is familiar to people working with hunting dogs, primarily Pointers and Labrador Retrievers. The typical case consists of an adult dog that suddenly develops a flaccid tail. The tail either hangs down from the tail base or is held out horizontally for several inches from the tail base and then hangs straight down or at some degree below horizontal. Initially, the hair on the dorsal aspect of the proximal tail may be raised and dogs may resent palpation of the area 3-4 inches (8-10 cm) from the tail base. Most dogs recover spontaneously within a few days to weeks. Anecdotal reports suggest that anti-inflammatory drugs administered within 24 hours after onset hasten recovery. Less than one half of affected dogs experience a recurrence. Affected Pointers almost always have a history of prolonged cage transport, a hard workout the previous day, or exposure to cold or wet weather Most owners and trainers familiar with the condition do not seek veterinary assistance. In cases where people are not familiar with this disease, other conditions such as a fracture, spinal cord disease, impacted anal glands, or prostatic disease have been incorrectly diagnosed. We examined 4 affected Pointers and found evidence of coccygeal muscle damage, which included mild elevation of creatine kinase early after onset of clinical signs, needle electromyographic examination showing abnormal spontaneous discharges restricted to the coccygeal muscles several days after onset, and histopathologic evidence of muscle fiber damage. Specific muscle groups, namely the laterally positioned intertransversarius ventralis caudalis muscles, were affected most severely. Abnormal findings on thermography and scintigraphy further supported the diagnosis. 相似文献
995.
Botha CJ Schultz RA Van Der Lugt JJ Retief E Labuschagne L 《The Onderstepoort journal of veterinary research》1999,66(3):237-244
The plant Nierembergia hippomanica var. violacea has been incriminated in field outbreaks of neurotoxicity in calves in the Free State Province. Hepatotoxicity and electrocardiogram (ECG) deviations were induced in a sheep dosed with 5 g/kg dried plant material on four consecutive days. A calf dosed with 2.5 g/kg dried plant material, on two consecutive days, did not show overt clinical changes. Voluntary ingestion of approximately 30 g/kg fresh flowering plants by a second calf resulted in nervous signs characterized by chewing motions, protrusion of the tongue, dysphagia, hypermetria, ataxia, paresis and lateral recumbency. Salivation, dehydration and cardiac irregularities completed the clinical picture. Clinical chemistry changes revealed muscle damage and increased serum urea and creatinine concentrations indicative of kidney involvement. This is the first confirmed outbreak of Nierembergia hippomanica var. violacea intoxication of stock in South Africa. 相似文献
996.
S B James R A Cook B L Raphael M D Stetter P Kalk K MacLaughlin P P Calle 《Journal of zoo and wildlife medicine》1999,30(4):521-525
Twelve babirusa (Babyrousa babyrussa) (four females/eight males) were immobilized 30 times during a 4-yr interval. Significantly higher premedication and immobilizing doses were needed for females than for males (P < 0.05). An i.m. preanesthetic xylazine dose of 1.88 +/- 0.37 mg/kg (range = 1.20-2.12 mg/kg) was used for females and 1.22 +/- 0.16 mg/kg (range = 0.82-1.43 mg/kg) for males. After xylazine, the animals were induced with i.m. tiletamine/zolazepam; females received 2.20 +/- 0.47 mg/kg (range = 1.78-3.33 mg/kg) and males received 1.71 +/- 0.34 mg/kg (range = 1.08-2.05 mg/kg). Anesthesia was reversed with yohimbine (0.14 +/- 0.03 mg/kg; range = 0.07-0.20 mg/kg) and flumazenil (1 mg flumazenil/20 mg zolazepam) either i.m. or i.v. This anesthetic combination produced smooth induction, good relaxation, and sufficient immobilization to perform routine diagnostic and therapeutic procedures (venipuncture, hoof and tusk trims, transportation, radiographs, ultrasound examination, weight determinations, and skin biopsies). Supplemental ketamine HCl or isoflurane was administered to two animals to effectively deepen or prolong the anesthetic plane, with no resultant adverse effects. 相似文献
997.
T L Lightfoot 《Veterinary Clinics of North America: Exotic Animal Practice》1999,2(2):447-69, vii
Veterinarians in small animal practice are being presented with an ever-increasing number of exotic species. It has become critical that veterinarians expand their professional knowledge to include the basic procedures necessary for the proper diagnosis and therapy of these animals. Yet the husbandry, temperaments, physiology, and anatomy of many of these species make extrapolation from our well-developed techniques in dog and cat medicine inadequate. This article discusses some of the major species concerns and clinical findings of chinchillas, hedgehogs, prairie dogs, and sugar gliders presented to the veterinary practitioner. Practical techniques for evaluation of these animals with minimal stress (to the animal, the practitioner, and the client) and maximum efficiency are addressed. 相似文献
998.
A corneo-conjunctival dermoid is reported in a blue-fronted Amazon parrot ( Amazona aestiva ). After laminar keratectomy, histology showed the epidermis with feather follicles and dermal connective tissue with lymph follicles and sebaceous glands. 相似文献
999.
Philip J. Johnson BVSc MS MRCVS David A. Wilson DVM MS Kevin G. Keegan DVM MS Kristan L. Purcell DVM Lorie A. Moore DVM MS John M. Kreeger DVM PhD Rebecca L. Frankeny VMD MS Jimmy C. Lattimer DVM PhD 《Journal of Equine Veterinary Science》1999,19(3):190
We retrospectively evaluated the medical records and obtained follow-up information for nine horses which had been treated for cecocolic intussusception (CCI) between January 1982 and April 1998. During the 16-year study period, CCI was diagnosed in nine of 748 horses in which exploratory celiotomy was undertaken for abdominal pain, representing an incidence of 1.2%. Most affected horses (78%) were less than four years of age (median age was 12 months, age range was five months to 15 years). Cecocolic intussusception affected male horses (78%) more commonly than female horses. The most common clinical presentation was abdominal pain of a severe, acute nature or milder but recurrent signs of abdominal pain persisting in spite of conservative treatment for several days. Correction of CCI by either simple reduction or reduction followed by partial typhlectomy was successful if compromise of the intestine by devitalization and adhesion formation was not found at surgery. Definitive diagnosis of CCI necessitates exploratory celiotomy, although an ultrasonographic examination of the abdomen may confirm the diagnosis in some cases. When recognized early during the course of disease, surgical correction of CCI is associated with a favorable outcome; of the eight horses which underwent surgery in our series, five horses (63%) survived surgical correction of CCI. Handling of compromised gut during reduction of CCI necessitates extreme caution because the risk of intestinal tearing is quite high. 相似文献
1000.
A brief review of procedures and potential problems associated with the diagnosis of porcine reproductive and respiratory syndrome 总被引:6,自引:0,他引:6
Experience has shown that, for a number of reasons, a diagnosis of porcine reproductive and respiratory syndrome (PRRS) is sometimes difficult. In this review we discuss: (1) field observations and laboratory tests that are useful in arriving at a definitive diagnosis; (2) the impact of so-called atypical PRRS on diagnostic procedures in North America; (3) the means by which diagnostic problems can often be circumvented by appropriate sample selection; and (4) methods used for presumptive identification of PRRS virus strains. 相似文献