全文获取类型
收费全文 | 1220篇 |
免费 | 78篇 |
国内免费 | 163篇 |
专业分类
林业 | 50篇 |
农学 | 95篇 |
基础科学 | 231篇 |
155篇 | |
综合类 | 385篇 |
农作物 | 21篇 |
水产渔业 | 57篇 |
畜牧兽医 | 423篇 |
园艺 | 22篇 |
植物保护 | 22篇 |
出版年
2024年 | 5篇 |
2023年 | 16篇 |
2022年 | 24篇 |
2021年 | 45篇 |
2020年 | 49篇 |
2019年 | 57篇 |
2018年 | 34篇 |
2017年 | 62篇 |
2016年 | 62篇 |
2015年 | 66篇 |
2014年 | 67篇 |
2013年 | 66篇 |
2012年 | 86篇 |
2011年 | 97篇 |
2010年 | 81篇 |
2009年 | 89篇 |
2008年 | 61篇 |
2007年 | 91篇 |
2006年 | 60篇 |
2005年 | 58篇 |
2004年 | 30篇 |
2003年 | 35篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 24篇 |
1999年 | 23篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 2篇 |
排序方式: 共有1461条查询结果,搜索用时 15 毫秒
101.
苏雷 《甘肃农业大学学报》1995,30(1):13-18
将55例大肠阻塞马骡分为4组,分别静脉输入5%、10%、50%葡萄糖溶液和2:1平衡液,实验表明:大肠阻塞马骡不宜补糖;采用一定剂量、速度和间隔时间对大肠阻塞马骡输入2:1平衡液可纠正其高血糖、脱水和酸中毒等症状。 相似文献
102.
通过引入泛复变量求解Navier-Stokes方程,得到不可压缩流体Navier-Stokes方程的一种泛复数解,即速度场和压强场的泛复数表示。 相似文献
103.
目的 :了解中枢神经系统 (CNS)感染性疾病患儿脑脊液中细胞因子水平对化脓性脑膜炎与病毒性脑炎的鉴别诊断价值。方法 :采用双抗体夹心ELISA法检测化脓性脑膜炎、病毒性脑炎和非CNS感染性疾病患儿脑脊液中的G CSF、TNF α、IL 8和sIL 2R水平 ,观察它们与粒细胞、蛋白含量和糖定量间的相关性并对它们在不同疾病组脑脊液中的水平进行比较。结果 :中枢神经系统 (CNS)感染性疾病患儿脑脊液中的G CSF、IL 8、sIL 2R与粒细胞计数呈正相关 (P均 <0 .0 5 ) ;化脓性脑膜炎组脑脊液中G CSF、IL 8明显高于病毒性脑炎组 (P均 <0 .0 1) ,而TNF α、sIL 2R与病毒性脑炎组的差异无显著性 (P均 >0 .0 5 )。病毒性脑炎组脑脊液中的TNF α、sIL 2R均高于对照组 (P均 <0 .0 1) ,而G CSF、IL 8与对照组的差异无显著性 (P均 >0 .0 5 )。结论 :脑脊液中G CSF、IL 8水平对化脓性脑膜炎与病毒性脑炎的鉴别诊断有一定的价值 相似文献
104.
105.
介绍了利用自行设计、建造的流体阻力环道测试装置,采用行业标准中减阻率测定的评价流体--0号柴油在环道的力学性能测试,确定了其作为胀塑性流体的有关流动参数,为评价流体的阻力定量计算提供了依据. 相似文献
106.
在合理模拟临跨的静态荷载以及质量影响的基础上.采用三维有限元对南水北调工程洺河大型渡槽典型槽段单跨渡槽进行结构地震动力分析.对于影响渡槽结构动力响应的盆式支座、槽内水体与结构的流固耦合作用以及桩基-土体的动力相互作用,参照相关规范的原则和相关研究成果,在尽可能反映其实际影响和合理简化的基础上进行模拟,研究了结构自振特性、结构各部位的动力位移、应力以及内力响应.计算结果表明:采用不同水体模拟方法和不同计算分析方法得到的动力响应规律是一致的,动力响应值比较接近. 相似文献
107.
Preliminary observations on the effects of Meloxicam in a new model for acute intra-articular inflammation in dogs 总被引:1,自引:0,他引:1
The effects of intra-articular injection, on two occasions, 3 weeks apart, of the contrast agent Urografin on the cytological and biochemical characteristics of synovial fluid (SF) were examined in two studies in dogs. The first study provided baseline data in two non-medicated dogs. The second study used a cross-over design whereby 4 dogs received a 7-day oral treatment with either a placebo or meloxicam (0.2 mg/kg body weight daily) with a washout period of 3 weeks, in order to determine the effect of this new non-steroidal anti-inflammatory drug (NSAID) on the response to Urografin injection. SF samples were collected under general anaesthesia prior to and at 24 and 72 h after each Urografin injection. The volume, relative viscosity, white blood cell count and concentrations of protein, lactate dehydrogenase (LDH) and hyaluronic acid of these samples were determined.The results from both studies indicate that intra-articular injection of Urografin provoked a mild local transient inflammatory response, the most dramatic evidence of which was an increase in the white blood cell count in the SF after 24 h. In the second study, comparison of the synovial fluid measurements of the placebo-treated dogs at 24 h after Urografin injection with those prior to injection revealed significant increases in SF volume, white blood cell count, protein concentration and LDH activity and a significant reduction in relative viscosity. At 72 h after injection, only the white blood cell count and relative viscosity were significantly different from the pre-injection values. All of these measurements were, however, associated with high coefficients of variation, which must be taken into account in assessing the usefulness of the model for drug-testing purposes. Nevertheless, the administration of meloxicam significantly reduced the SF volume and white blood cell count at 24 h relative to the effects of concurrent placebo treatment. The general health status of the animals was not disturbed at any time as assessed by clinical and haematological observations. No adverse reactions were observed.Abbreviations LDH
lactate dehydrogenase
- NSAID
non-steroidal anti-inflammatory drug
- SF
synovial fluid
- WBC
white blood cell count 相似文献
108.
Raymond K. Henley DVM David A. Hager DVM Norman Ackerman DVM 《Veterinary radiology & ultrasound》1989,30(3):121-124
The detection of small amounts of free peritoneal fluid in the canine patient can be a diagnostic dilemma. Ultrasonography and radiography have been advocated to detect intraabdominal fluid not detectable by physical exam. The purpose of this study was to determine the more sensitive method for detecting small amounts of free peritoneal fluid. Ultrasound examinations and radiographs were performed after increments (1 ml/lb body weight) of fluid were injected intraperitoneally. Ultrasonography detected fluid in one animal at 2 ml/lb. AH other animals had fluid detected at 3 ml/lb. With radiographs fluid could be detected with a high degree of accuracy at 4 ml/lb. The lateral view was more accurate than the ventrodorsal view in detecting fluid. The authors concluded that Ultrasonography is more sensitive than radiography and is the method of choice to detect small amounts of free peritoneal fluid. 相似文献
109.
应用双抗体夹心法ELISA检测IBDV的研究 总被引:1,自引:0,他引:1
从抗IBDV高免蛋黄液中提取IgG,用作包被抗体和酶标记,建立了检测IBDV的双抗体夹心法ELISA。经抗原阻断,无关病毒对照、取代、验证等项试验,并与常规AGP法比较,对来源不同的100多个样品进行检测,结果表明:该法对患鸡腔上囊、脾脏的检出率均为100%,比AGP法敏感100倍以上,用肉眼观察阳性与阴性之间颜色差异显著,不存在非特异性反应。试验证明该法具有满意的待异性、敏感性、快速性和稳定性,是IBD早期病原学诊断和流行病学调查的有效手段。 相似文献
110.
Titers of two systemic neonicotinoid insecticides in citrus trees were measured in conjunction with conventional evaluations of their impact on glassy-winged sharpshooter (Homalodisca coagulata (Say); GWSS) populations. Xylem fluid samples were collected at regular intervals and from multiple locations within field-grown citrus trees to determine imidacloprid and thiamethoxam concentrations using commercial ELISA kits. Uptake profiles varied considerably with peak mean titers of imidacloprid occurring 6-8 weeks after application compared with 2 weeks for thiamethoxam. The persistence of each compound also varied as near-peak levels of imidacloprid were sustained for another 6-10 weeks before gradually declining. In contrast, thiamethoxam titers declined more rapidly after the initial peak, possibly reflecting an application rate only one-quarter of that used for imidacloprid. Within-tree distributions were more similar for the two compounds, with no significant effect due to height of the sample (upper or lower half) or to the quadrant location within the tree, with the exception of one quadrant in the thiamethoxam-treated trees. Substantial reductions in GWSS nymphs and adults were observed in imidacloprid-treated trees during the 2001 trial and were sustained for 4-5 months after treatment. Treatment effects on nymphs were not as well pronounced in the 2002 trial, when overall GWSS infestations were much reduced from the previous year. However, consistently lower adult infestations were still observed in 2002 for both treatments compared with untreated trees. Information on the spatial and temporal profiles in citrus trees was obtained for both compounds to complement field impact data and improve understanding of their pest management potential. 相似文献