全文获取类型
收费全文 | 936篇 |
免费 | 100篇 |
国内免费 | 57篇 |
专业分类
林业 | 5篇 |
农学 | 20篇 |
基础科学 | 14篇 |
38篇 | |
综合类 | 217篇 |
农作物 | 18篇 |
水产渔业 | 70篇 |
畜牧兽医 | 694篇 |
园艺 | 14篇 |
植物保护 | 3篇 |
出版年
2024年 | 5篇 |
2023年 | 15篇 |
2022年 | 42篇 |
2021年 | 55篇 |
2020年 | 53篇 |
2019年 | 46篇 |
2018年 | 48篇 |
2017年 | 47篇 |
2016年 | 40篇 |
2015年 | 39篇 |
2014年 | 49篇 |
2013年 | 53篇 |
2012年 | 50篇 |
2011年 | 49篇 |
2010年 | 44篇 |
2009年 | 47篇 |
2008年 | 51篇 |
2007年 | 47篇 |
2006年 | 38篇 |
2005年 | 33篇 |
2004年 | 30篇 |
2003年 | 23篇 |
2002年 | 15篇 |
2001年 | 16篇 |
2000年 | 23篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 3篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1093条查询结果,搜索用时 31 毫秒
91.
Xie Weimin Wang Qunhui Yao Jie Ma Hongzhi Ohsumi Yukihide Ogawa Hiroaki I. 《Water, air, and soil pollution》2004,159(1):313-324
The adsorption of a fixed bed filled with bone char was investigated in terms of its efficiency and capacity by determining operational conditions for the purpose of further reduction of organic matter and removal of phosphorus using a continuous flow of real secondary effluent. Simultaneous removals of phosphorus and chemical oxygen demand (COD) were sufficiently achieved by this fixed-bed method. Stable performance was maintained even at a linear flow velocity (abbreviated as LV) of 1.5 m h–1. Appropriate backwashing and regeneration were required to operate the system continuously for a long period of time. During the regeneration, the use of treated water including Ca2+ ion was so effective that phosphorus removal efficiency increased from about 50 to 80%, and afterwards maintained over 65%, until inflow water of the volume up to 150 times as large as the volume of bone char had passed through. Even when the inflow water of the volume rose up to 200 times, the phosphorus removal efficiency could be maintained over 50%. During this operation, the adsorptions of phosphorus and COD onto the bone char surface were observed to be over 6.7 and 35 gL–1, respectively. 相似文献
92.
M. Risselada DMV M. Kramer DVM PhD H. van Bree DVM PhD 《Veterinary radiology & ultrasound》2003,44(2):214-220
The objective of this study was to identify access portals for ultrasonographic evaluation of canine long bones (humerus, radius, ulna, femur, and tibia). A 7.5 MHz linear transducer was used in five medium-sized dogs (range of 25-35 kg body weight). Good approaches could be identified for all long bones. For the proximal humerus, a cranial portal, and the distal humerus, a lateral portal is suggested. For the radius and ulna, a craniolateral approach seemed to be the best. In the hindlimb, a medial approach for the femur and a craniolateral approach for the tibia were the most effective approaches. 相似文献
93.
硒对STZ诱发糖尿病大鼠骨密度影响的研究初报 总被引:1,自引:0,他引:1
比较了在低硒饲料的基础上补充不同形态硒对糖尿病大鼠骨密度的影响。健康SD大鼠 1 2 8只 ,体重 50~ 60 g,随机分为 4组 ,每组 32只 ,雌雄各半 ,其中Ⅰ组为低硒对照组 (饲料含硒量 0 0 37mg/kg) ;Ⅱ组为补充亚硒酸钠组 (饲料含硒量 0 3mg/kg) ;Ⅲ组为补充富硒麦芽组(饲料含硒量 0 3mg/kg) ;Ⅳ组为补充富硒酵母组 (饲料含硒量 0 3mg/kg)。Ⅱ、Ⅲ、Ⅳ组的饲料均是在Ⅰ组低硒饲料的基础上分别添加适量的亚硒酸钠、富硒麦芽、富硒酵母后配制而成。喂饲 5周后 ,Ⅰ、Ⅱ、Ⅲ、Ⅳ组用链脲佐菌素 (streptozotocin ,STZ)按 60mg/kg腹腔注射诱发糖尿病 ,继续饲喂 6周。用单光子吸收法测定各组大鼠的肱骨、股骨、胫骨、桡骨的骨密度。结果表明 :①STZ致糖尿病大鼠的骨密度随时间的延长有逐渐下降的趋势。Ⅱ、Ⅲ、Ⅳ补硒组大鼠可以在一定时间内延缓STZ致糖尿病大鼠的骨密度下降。在此期间骨密度的下降以肱骨出现最早 ,股骨次之 ,桡骨、胫骨再次之。②饲料补硒组糖尿病大鼠的肱骨、股骨中硒的含量较饲料低硒组糖尿病大鼠的肱骨、股骨中硒的含量显著提高。③补充硒的形态 ,即有机硒 (富硒麦芽、富硒酵母 )或无机硒 (亚硒酸钠 )对糖尿病大鼠肱骨、股骨、胫骨、桡骨的骨密度影响差异不显著。 相似文献
94.
ColinB. Carrig BVSc PhD JeffreyA. Wortman DVM PhD† EarlL. Morris DVM‡ WilliamE. Blevins DVM MS§ CharlesR. Root DVM MS GriseldaF. Hanlon DVM¶ PeterF. Suter Dr med vet 《Veterinary radiology & ultrasound》1981,22(3):123-144
Radiographs of 14 dogs with ectrodactyly of the forelimb were evaluated and the defect classified according to the site of division of the longitudinal axis of the paw. The majority of separations occurred between metacarpal bones one and two, although separations were also noted between metacarpal bones two and three, two and four, and three and four. Other lesions noted in affected limbs included digit contracture, digit aplasia, metacarpal hypoplasia and metacarpal fusions. Bilateral involvement was noted in only one of 14 cases. No breed or sex predisposition was found and there was equal involvement of the left and right limbs. 相似文献
95.
Constance E. De Haan DVM Timothy R. O'Brien DVM PhD Philip D. Koblik DVM MS 《Veterinary radiology & ultrasound》1987,28(3):88-92
A retrospective study of carpal radiographs from 42 racing thoroughbreds with carpal lameness was performed. Radiographs from 50 carpal examinations were available for review. The radiographic findings pertaining to the third carpal bone were described. Fractures and/or sclerosis occurred almost exclusively within the radial fossa. The occurrence of sclerosis without fracture in 20 of the 50 carpal examinations was higher than anticipated, occurring in both the right and left third carpal bone with equal frequency. The right third carpal bone was more frequently fractured and more severely affected than the left. The sclerotic changes seen in the radial fossa of the third carpal bone may be stress-induced, possibly preceding more serious changes in the joint such as cartilage damage or gross fracture. Earlier recognition of sclerosis of the third carpal bone may help prevent more serious changes from occurring. 相似文献
96.
Tarsal radiographs of 134 trotters were made prior to training. Radiographs were evaluated for changes commonly associated with spavin. Spavin, if present, was graded as mild, moderate, or severe. Sone of the 134 horses were radiographed annually for one, two, or three years. Radiographs of the 134 horses were compared with radiographs of 141 additional horses in which spavin had been diagnosed clinically. Only 66 of the 134 trotters (50.4%) had normal tarsal radiographs at the time of initial examination; the other 65 had some radiographic evidence of spavin. The incidence and severity of radiographic changes identified in a group of horses in which spavin was diagnosed clinically. Thus, the present results suggest that tarsal radiography is of little value in establishing the diagnosis and prognosis of spavin in trotters. 相似文献
97.
B. A. Selcer 《Veterinary radiology & ultrasound》1983,24(6):243-250
Bone can be imaged by a variety of methods including survey radiography, stress radiography, contrast radiography, fluoroscopy, tomography, magnification radiography, xeroradiography, and nuclear imaging. Each of these imaging techniques and modalities is presented as it applies to diagnostic imaging of bone in veterinary medicine 相似文献
98.
From progeny lists of 30 Dutch Warmblood sires, 586 3-year-old females by these stallions were randomly selected, each progeny group aimed at 20 animals for statistical reasons. The front feet of the sires and female progeny were examined radiographically using lateromedial and dorsopalmar upright pedal projections. The radiological features associated with navicular disease were classified 0–4 using a standardised classification, grades 3 and 4 representing the more severe changes. The shape of the proximal articular border of the navicular bone outlined on the dorsopalmar view was classified 1–4: l=concave; 2=undulating; 3=straight; 4=convex. A significant shape-grade association was found, the highest grades 3 and 4 incidence associated with shape 1 and the lowest grades 3 and 4 incidence demonstrated by shape 4. In shapes 1 and 2, navicular bones grades 3 and 4 features were mainly characterised by inverted flask-shaped channels. In shape 3, navicular bones grades 3 and 4 were dominated by enthesiophytes. These findings indicate an apparent shape predisposition to radiological changes associated with navicular disease. The shape of the navicular bone in the offspring was on average the same as the sire, indicating an hereditary element in navicular bone shape. 相似文献
99.
100.
乌鸡的血清蛋白质多态性与其遗传关系的研究 总被引:13,自引:1,他引:12
采用聚丙烯酰胺凝胶和聚丙烯酰胺浓度梯度凝胶电泳法分析了我国三种乌鸡(泰和、略阳、雪峰)的血清蛋白质多态性,并以引进鸡种(来航、罗斯)作对照,以揭示三种乌鸡间的遗传关系。电泳结果表明,鸡血清蛋白质在前白蛋白(Pa)、白蛋白(Alb)、运铁蛋白(Tf)、脂酶(Es-1)、碱性磷酸酶(AKP,AKP-2)、诸位点显示多态。借助所测位点的基因频率,计算了群体平均基因杂合度和标准遗传距离。采用最短距离法对所研究鸡种进行了聚类分析。结果表明,我国三种乌鸡虽相对于外国鸡种具有较近的亲缘关系,但彼此之间呈现一定的遗传差异。结合体型外貌特征和地理隔离等因素综合考虑,它们似应看作独立的地方品种,不存在同种异名的问题。 相似文献