首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   688篇
  免费   56篇
林业   30篇
农学   46篇
基础科学   2篇
  96篇
综合类   30篇
农作物   152篇
水产渔业   57篇
畜牧兽医   286篇
园艺   6篇
植物保护   39篇
  2023年   5篇
  2022年   25篇
  2021年   25篇
  2020年   14篇
  2019年   18篇
  2018年   30篇
  2017年   26篇
  2016年   30篇
  2015年   27篇
  2014年   38篇
  2013年   48篇
  2012年   56篇
  2011年   63篇
  2010年   38篇
  2009年   37篇
  2008年   40篇
  2007年   50篇
  2006年   41篇
  2005年   32篇
  2004年   29篇
  2003年   27篇
  2002年   14篇
  2001年   18篇
  2000年   8篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
排序方式: 共有744条查询结果,搜索用时 15 毫秒
161.
A two-year-old male Pointer had been presented with anorexia, cachexia, and weight loss of 10-day duration. Upon physical examination, fever, lethargy, superficial lymph node enlargement, and tick infestation were noted. The only abnormality in CBC and serum chemistry analyses was mild hyperglobulinemia. Spleen was enlarged by radiography, and the lymph nodes showed neutrophilic lymphadenitis by cytological examination. A polymerase chain reaction test for babesiosis and commercial ELISA tests for Ehrlichia canis, heartworm, and Lyme disease was negative except for Lyme disease, which was verified by both an IFA-IgG test and a quantitative C6 assay. Doxycycline was administered for 2 weeks and the recovery was uneventful. Post-treatment C6 titer decreased to within normal limits.  相似文献   
162.
A 1.5-year-old female Persian cat was presented for inappetence and azotemia. Ultrasonography and urography revealed multiple abnormalities involving the genitourinary tract, including agenesis of the right kidney and ureter. Gross examination of the abnormal uterus revealed segmental aplasia of right caudal uterine horn causing cranial distension with fluid, a normal left uterine horn, and both normal ovaries. Microscopically, endometrial glands of the right uterine horn were markedly decreased in number. The right uterine horn was hemorrhagic suggesting estrus. This is the first report of this combination of urinary and uterus abnormalities in the veterinary literature.  相似文献   
163.
To evaluate the differences in graft survival and histopathological characteristics between full-thickness and lamellar orthotopic corneal xenotransplantation in a pig-to-rabbit model, we orthotopically transplanted a full-thickness or the anterior half of a pig's cornea onto the OD of 16 rabbits. As a result, the median survival were 16.83 and 29.07 days for the full-thickness and lamellar xenografts, respectively ( P  = 0.0005). Histologically, the full-thickness corneal xenografts had massive infiltration by eosinophils, whereas the lamellar xenografts showed predominantly mononuclear infiltrates ( P  < 0.05). Given these preliminary findings, lamellar corneal xenografts in rabbits survived longer than the full-thickness xenografts and each type of graft demonstrated different rejection mechanisms.  相似文献   
164.
To clarify nitrogen (N) sources, the overall N budget in a forested watershed in Kanagawa Prefecture, Central Japan was estimated by measuring dissolved inorganic N (DIN; NH4 + + NO3 + NO2 ) from Nov 2004 through Oct 2005. The estimated N budget (–1.43 kg N ha–1 year–1) showed that the N output rate (stream water N) was higher than the N input rate (bulk deposition N) in the watershed. The annual NO2 and NO3 input rates were 0.02 and 1.99 kg N ha–1 year–1, respectively. NH4 + was the predominant source in this forested watershed, accounting for 71% (4.99 kg N ha–1 year–1) of DIN input rate. In addition, this study estimated rainfall pH, air temperature, and wind direction, which were considered as controlling factors related to the atmospheric deposition rate of NH4 +. This study showed that the rainfall NH4 + was inversely proportional to the initial pH of the rainfall, which was calculated by adding the amount of H+ consumed by the dissociation process of NH3(aq) to the measured rainfall pH. This result implies that acid rain can elevate the solubility of NH3(g) and the dissociation capacity of NH4 + throughout the process of precipitation. Also, this study provides strong evidence that the high NH4 + deposition rate is mainly derived from NH3(g) emitted from livestock wastes under the NH3 transport condition of warm summer and favorable wind direction.  相似文献   
165.
Plant growth promoting rhizobacteria (PGPR) has been a focus of research for its potential as an eco-friendly alternative to chemical fertilizers in the agriculture industry. In current study, the effect of culture suspension (CS) of a novel gibberellins (GAs) producing bacterial strain Burkholderia sp. KCTC 11096BP, was observed on shoot length, shoot fresh and dry biomass, root fresh and dry biomass, chlorophyll contents, endogenous bioactive GAs (GA1 and GA4) and their immediate precursors, abscisic acid (ABA), soluble sugar contents and crude protein contents of cucumber (Cucumis sativus L.). We found that growth attributes of cucumber were significantly promoted by the application of CS of Burkholderia sp. KCTC 11096BP. The quantity of GA1 and GA4 and their immediate precursors GA20 and GA9 respectively, were also significantly promoted as compared to their respective controls. Contrary to GAs, the quantity of endogenous free ABA in cucumber leaves was much lower in bacterial CS treated plants. Soluble sugar contents and crude protein contents of cucumber leaves were also significantly higher in bacterial CS treatments as compared to control. It was concluded that Burkholderia sp. KCTC 11096BP can be used as an eco-friendly bio-fertilizer in our farming systems.  相似文献   
166.
Necrotic enteritis (NE) and gangrenous dermatitis (GD) are important infectious diseases of poultry. Although NE and GD share a common pathogen, Clostridium perfringens, they differ in other important aspects such as clinical signs, pathologic symptoms, and age of onset. The primary virulence factors of C perfringens are its four major toxins (alpha, beta, epsilon, iota) and the newly described NE B-like (NetB) toxin. While neutralizing antibodies against some C perfingens toxins are associated with protection against infection in mammals, the serologic responses of NE- and GD-afflicted birds to these toxins have not been evaluated. Therefore, we measured serum antibody levels to C perfringens alpha-toxin and NetB toxin in commercial birds from field outbreaks of NE and GD using recombinant toxin-based enzyme-linked immunosorbent assay (ELISA). Initially, we used this ELISA system to detect antibody titers against C perfringens alpha-toxin and NetB toxin that were increased in birds experimentally coinfected with Eimeria maxima and C perfringens compared with uninfected controls. Next, we applied this ELISA to field serum samples from flock-mated birds with or without clinical signs of NE or GD. The results showed that the levels of antibodies against both toxins were significantly higher in apparently healthy chickens compared to birds with clinical signs of NE or GD, suggesting that these antitoxin antibodies may play a role in protection against NE and GD.  相似文献   
167.
168.
In the present study, we demonstrated that heat shock protein 70 (Hsp70) was present in both canine reticulocytes and mature erythrocytes, and that the canine Hsp70 in reticulocytes was decreased along with the maturation of the cells into erythrocytes. These results suggest that the Hsp70 in canine reticulocytes might act as a chaperone to remove unnecessary proteins during reticulocyte maturation. We also demonstrated that Hsp70 was present in exosomes from reticulocytes during their maturation in in vitro culture. Furthermore, the concentration of Hsp70 in reticulocyte membranes was increased in proportion to an increase of the protein in exosomes until 48 hours after the incubation of reticulocytes in vitro. At 96 hours of the incubation, however, only a trace amount of Hsp70 was detected in the membrane, while a large amount of the protein was present in the exosomes. These results suggest that Hsp70 in canine reticulocytes might play an important role for exosome formation in reticulocytes, resulting in the maturation of the cells.  相似文献   
169.
cDNA of cyclin-dependent kinase 5 (Cdk5) was cloned based on its primary sequence homology to Cdc2 and Cdk2. Cdk5 requires the neuronal Cdk5 activators such as p35 or p39(nck5ai) (p39) for its activity. In this study, we examined post-natal changes in the p39 expression pattern during the development of the rat cerebellum. p39 began to express in somata and dendrites of Purkinje cells at post-natal day 3 (PD3). In particular, at PD12, parasagittal bands (stripes) with p39 immunoreactivity were weakly observed. At PD21, p39-immunoreactive stripes were developed when compared with the PD12 group. At this age stage, p39 immunoreactivity became weak in somata of Purkinje cells, not forming stripes. At PD28, a series of parasagittal bands were more distinct than those of the PD21 group, and p39 immunoreactivity disappeared in Purkinje cells, not forming p39 immunoreactive stripes. In the adults, p39 immunoreactivity in Purkinje cells was similar to that found in the PD28 group which showed that parasagittal bands were very narrow, and became progressively more slender. Therefore, we suggest that the post-natal changes of p39 expression in Purkinje cells in the cerebellum is an autonomous characteristic of Purkinje cells with a role of Cdk5 activators.  相似文献   
170.
Among many detrimental injuries, alcohol is implicated in hepatitis, fatty liver, hepatic fibrosis, and cirrhosis. The purpose of this study was to evaluate the protective effect of bio-active ceramic water on alcohol-induced hepatic injury in pigs. Twelve male Landrace pigs were divided into 3 groups. Groups 1, 2, and 3 were fed with bio-active ceramic water + normal liquid diet, bio-active ceramic water + liquid diet containing 15% ethanol, and tap water + liquid diet containing 15% ethanol for 12 weeks, respectively. For serological, histopathological, and immunohistochemical analysis, all pigs were sacrificed at week 12. In group 3, serum ALT and AST levels increased, and mild fatty change and moderate necrosis were detected in the liver. Collagen fibers, myofibroblasts, and CYP2E1 were also increased or activated in group 3. In group 2, there were mild hepatic injuries compared to group 3. However, injuries and activations were not observed in the liver in group 1. We suggest that the bio-active ceramic water used in the present study had protective capability against ethanol-induced hepatic injury and that having no toxic effect on the pig liver. The bio-active ceramic water might be useful as a therapeutic drinking water in patients suffering from alcoholic liver diseases.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号