全文获取类型
收费全文 | 269958篇 |
免费 | 14650篇 |
国内免费 | 182篇 |
专业分类
林业 | 10901篇 |
农学 | 8635篇 |
基础科学 | 1770篇 |
32996篇 | |
综合类 | 47927篇 |
农作物 | 10472篇 |
水产渔业 | 13543篇 |
畜牧兽医 | 136574篇 |
园艺 | 3659篇 |
植物保护 | 18313篇 |
出版年
2019年 | 2425篇 |
2018年 | 3620篇 |
2017年 | 4037篇 |
2016年 | 3794篇 |
2015年 | 3238篇 |
2014年 | 4034篇 |
2013年 | 10553篇 |
2012年 | 7381篇 |
2011年 | 9124篇 |
2010年 | 6047篇 |
2009年 | 5948篇 |
2008年 | 8878篇 |
2007年 | 8587篇 |
2006年 | 8158篇 |
2005年 | 7539篇 |
2004年 | 7365篇 |
2003年 | 7402篇 |
2002年 | 7007篇 |
2001年 | 8407篇 |
2000年 | 8129篇 |
1999年 | 6550篇 |
1998年 | 2786篇 |
1997年 | 2763篇 |
1996年 | 2540篇 |
1995年 | 3053篇 |
1994年 | 2760篇 |
1993年 | 2767篇 |
1992年 | 5471篇 |
1991年 | 5711篇 |
1990年 | 5725篇 |
1989年 | 5820篇 |
1988年 | 5290篇 |
1987年 | 5443篇 |
1986年 | 5514篇 |
1985年 | 5259篇 |
1984年 | 4396篇 |
1983年 | 3957篇 |
1982年 | 2788篇 |
1981年 | 2569篇 |
1979年 | 3896篇 |
1978年 | 3219篇 |
1977年 | 2777篇 |
1976年 | 2607篇 |
1975年 | 2757篇 |
1974年 | 3439篇 |
1973年 | 3549篇 |
1972年 | 3414篇 |
1971年 | 3072篇 |
1970年 | 3039篇 |
1969年 | 2822篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
991.
992.
The objective of this study was to report our experience with an absorbable haemostatic gauze product in 20 horses with traumatic or surgical haemorrhage. The product is made from oxidised, regenerated cellulose (ORC) and is approved for external use and currently being studied to control internal bleeding in surgical settings in human subjects. Treated horses were from both practice and university settings. Signalment, anatomic location, underlying cause of bleeding and outcome were recorded in the medical record. The size of gauze, approximate time until bleeding stopped, and pre- and post-ORC adjunctive treatments were also recorded. The ORC was used in a variety of anatomic locations, including castration site, foot, flank incisions, distal limb, tooth extraction sites and the perineal region. The bleeding stopped or slowed dramatically within 90 s in 15 of 20 cases. There were no recorded complications in any of the cases. While this clinical report does not attempt to prove efficacy of the product in horses, it does show that this ORC product, which has been approved for use as a haemostatic agent in human subjects, is safe and of practical value, and may be a useful and viable option for the control of haemorrhage in a variety of equine clinical settings. 相似文献
993.
Electron microscopy of equine respiratory viruses in organ cultures of equine fetal respiratory tract epithelium 总被引:1,自引:0,他引:1
Organ cultures of equine fetal tracheal and nasal turbinate epithelium were inoculated with equine influenza virus-A1 (EIV-A1), equine herpesvirus-1 (EHV-1), or equine rhinovirus-1 (ERV-1). Infected organ cultures were processed for scanning and transmission electron microscopy at various intervals and were compared with noninfected controls. Organ cultures inoculated with ERV-1 appeared normal with the exception of rare island-like lesions in infected nasal turbinate. Virus particles were not seen in thin sections of organ cultures infected with ERV-1. The EHV-1 caused extensive loss of the epithelial layer in tracheal and nasal turbinate organ cultures. The classic stages of herpesvirus morphogenesis were seen in thin sections of organ cultures infected with EHV-1. The EIV-A1 caused a scattered loss of cilia that was only apparent in infected tracheal organ cultures. Cilia were also seen bound in bundles. In thin sections, EIV-A1 particles were seen budding from the bases of microvilli. 相似文献
994.
A comparison of three micro-assay detection systems for naturally occurring and experimentally induced rat antibody to Mycoplasma pulmonis was performed. The micro-enzyme linked immunoabsorbent assay was found superior to counter immunoelectrophoresis or complement fixation techniques when comparing sensitivity, duration of antibody response, or technical requirements. The primary immune response was routinely detected at 3 weeks after antigen exposure when using the enzyme linked or complement fixation assays. 相似文献
995.
Direct immunofluorescence on impression smears of brain and pharynx was compared with virus isolation in cell culture for the diagnosis of Aujeszky's disease in experimentally and naturally infected pigs. Pharyngeal impression smears were more sensitive than virus isolation in two pigs killed 10 and 12 days after experimental infection. Both methods were of similar sensitivity in the detection of virus from field cases of disease. Smears of brain and pharynx were more sensitive than virus isolation for tissue which had been stored at room temperature (approximately 20 degrees C) for up to 48 hours. Some reduction in the amounts of virus recovered from tissues and the intensity of fluorescent staining occurred in these samples. 相似文献
996.
Thirteen cases of botulism in horses fed big bale silage 总被引:2,自引:0,他引:2
S W Ricketts T R Greet P J Glyn C D Ginnett E P McAllister J McCaig P H Skinner P M Webbon D L Frape G R Smith 《Equine veterinary journal》1984,16(6):515-518
An outbreak of pharyngeal and limb paresis involving four horses and nine ponies in the south east of England is described. Nine of the animals died or were destroyed on humane grounds. The clinical features suggested a diagnosis of botulism and mouse innoculation tests confirmed the presence of type B toxin in the serum of one case. All animals were fed big bale silage. It is describe how, in plastic wrapped silage manufacture, conditions of fermentation may be inadequate to prevent the growth of Clostridium botulism. Examination of a sample of silage fed to the affected horses suggested that this was probably the source of the toxin. 相似文献
997.
998.
Effects of adrenergic agonists and antagonists on the blood pressure and heart rate of the pig fetus
The effects of adrenergic agonists and antagonists on blood pressure and heart rate were investigated in 18 chronically catheterised pig fetuses aged between 102 and 109 days of gestation (term is 114 days). One fetus had been decapitated in utero at 42 days of gestation. The alpha adrenergic agonist methoxamine produced a small but dose dependent hypertension and a dose related slowing in heart rate. The beta adrenergic agonist isoprenaline decreased mean arterial pressure in a dose related manner and produced tachycardia. Propranolol, a beta adrenergic blocker, increased mean arterial pressure and decreased heart rate. The response to subsequent alpha adrenergic blockade with phentolamine was hypotension and a slight bradycardia. Decapitation at 42 days of gestation did not seem to change the fetal responsiveness to adrenergic agonists but removed the blood pressure response to beta blockade. These observations indicate that the heart and circulation of the pig fetus are under adrenergic vasomotor control during late gestation. 相似文献
999.
E A Mahaffey A M Buonanno L M Cornelius 《American journal of veterinary research》1984,45(10):2126-2128
Glycosylated albumin and glycosylated protein in serum were measured in 4 well-controlled diabetic dogs, 4 poorly controlled diabetic dogs, and 21 nondiabetic dogs. Concentrations of both glycosylated components in the well-controlled dogs were similar to those in nondiabetic dogs. Serum concentrations of glycosylated albumin and protein in the poorly controlled diabetic dogs were higher (P less than 0.001) than those of the nondiabetic and well-controlled diabetic dogs. Because of the essentially irreversible nature of the glycosylation reaction and the relatively short turnover time of albumin and other serum proteins, measurements of glycosylated serum components may provide an index of glycemia during the preceding days or weeks. 相似文献
1000.
Multiple apparent Sarcocystis abortion in four bovine herds 总被引:1,自引:0,他引:1
Foetuses recovered from multiple abortions in four dairy herds had multifocal nonsuppurative encephalitis, myocarditis and hepatitis. Focal placentitis was usually present. Sarcocystis-like protozoa were found in the brains of foetuses from two of the outbreaks. Apart from excess salivation in a few cows in one herd, farmers reported no clinical abnormalities prior to the abortions, and all cows remained normal after the abortions. Dogs and cats fed an affected foetus and neonatal calves from the affected herds failed to excrete protozoa in their faeces. The identity of the protozoa in the foetal brain was not confirmed. 相似文献