全文获取类型
收费全文 | 11407篇 |
免费 | 640篇 |
国内免费 | 969篇 |
专业分类
林业 | 764篇 |
农学 | 855篇 |
基础科学 | 331篇 |
1707篇 | |
综合类 | 3489篇 |
农作物 | 1715篇 |
水产渔业 | 288篇 |
畜牧兽医 | 2248篇 |
园艺 | 1123篇 |
植物保护 | 496篇 |
出版年
2024年 | 93篇 |
2023年 | 241篇 |
2022年 | 426篇 |
2021年 | 486篇 |
2020年 | 428篇 |
2019年 | 579篇 |
2018年 | 529篇 |
2017年 | 418篇 |
2016年 | 675篇 |
2015年 | 918篇 |
2014年 | 1016篇 |
2013年 | 1013篇 |
2012年 | 992篇 |
2011年 | 708篇 |
2010年 | 570篇 |
2009年 | 573篇 |
2008年 | 467篇 |
2007年 | 496篇 |
2006年 | 561篇 |
2005年 | 426篇 |
2004年 | 215篇 |
2003年 | 156篇 |
2002年 | 130篇 |
2001年 | 114篇 |
2000年 | 140篇 |
1999年 | 77篇 |
1998年 | 85篇 |
1997年 | 48篇 |
1996年 | 44篇 |
1995年 | 74篇 |
1994年 | 43篇 |
1993年 | 34篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 32篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 27篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
111.
Mariarita Romanucci Paolo E. Crisi Maria Veronica Giordano Morena Di Tommaso Francesco Simeoni Leonardo Della Salda 《Journal of veterinary diagnostic investigation》2021,33(1):112
A 14-y-old spayed female Labrador Retriever was presented with an 8-mo history of chronic vomiting. Abdominal ultrasound and gastrointestinal endoscopy revealed a mass protruding into the gastric lumen, with cytologic features suggestive of sarcoma. A partial gastrectomy was performed; the gastric body and antrum were thickened, with a cerebriform appearance of the mucosal surface. Histologic examination revealed a submucosal neoplastic proliferation of fusiform cells variably arranged in irregular bundles and scattered whorls. Fusiform cells strongly reacted to antibodies against vimentin, S100, and neuron-specific enolase; glial fibrillary acidic protein was moderately and multifocally expressed. Pancytokeratin, KIT, α–smooth muscle actin, and desmin were nonreactive. Histologic and immunohistochemical findings suggested a diagnosis of gastric sarcoma with features referable to a non-GIST (gastrointestinal stromal tumor), non–smooth muscle NIMT (non-angiogenic, non-lymphogenic intestinal mesenchymal tumor). The overlying gastric mucosa was thickened by elongated and dilated gastric glands, predominantly lined by intensely periodic acid-Schiff–stained mucous cells. This altered mucosal architecture was suggestive of Ménétrier-like disease. Although this disease has been hypothesized to predispose to gastric adenocarcinoma in dogs, an association with gastric sarcoma has not been documented previously in the veterinary literature, to our knowledge. 相似文献
112.
本研究旨在利用原核表达系统表达新型鸭呼肠孤病毒(NDRV) DH13株重组σB蛋白,并检测其免疫原性,为NDRV基因工程疫苗研制等提供物质材料。采用RT-PCR方法扩增获得NDRV σB基因,构建原核表达重组质粒pET-30a-σB和pET-32a-σB,将2个重组质粒转化大肠杆菌BL21(DE3)感受态细胞,利用IPTG诱导获得相应的重组蛋白,通过SDS-PAGE分析重组蛋白的表达形式。纯化无His的σB蛋白,并以此蛋白作为免疫原免疫新西兰白兔,制备兔源多克隆抗体。利用Ni2+柱亲和层析法纯化含His的σB蛋白,以此蛋白作为检测原,通过间接ELISA方法测定兔源多克隆抗体效价;Western blotting鉴定多克隆抗体与重组蛋白的特异性识别能力。结果显示,PCR扩增获得大小约为1 100 bp的σB基因片段。SDS-PAGE结果显示,高效表达出了2种重组σB蛋白,大小分别约为41和46 ku,均以包涵体形式存在。间接ELISA结果显示,制备的多克隆抗体效价达1∶204 800,能特异性地识别原核表达的重组蛋白,表明重组无His的σB蛋白具有良好的免疫原性。Western blotting特异性鉴定结果显示,含His的σB蛋白和无His的σB蛋白均与制备的兔源多克隆抗体发生特异性反应,表明原核表达得到的重组σB蛋白具备良好的反应原性。本试验利用原核表达系统成功地表达出了重组σB蛋白,并证实了重组NDRV σB蛋白具有良好的免疫原性及反应原性,该结果将有助于后续对NDRV σB蛋白生物学功能的鉴定、NDRV诊断用抗原的制备及NDRV新型疫苗的研制。 相似文献
113.
The objective of this study was to develop equations for estimating ileal digestible crude protein (CP) and metabolizable energy (ME) contents of meat meal (MM) and meat and bone meal (MBM) as feed ingredients for pigs based on in vitro assays. Test ingredients were 4 sources of MM and 3 sources of MBM. Ash and CP contents of the ingredients ranged from 3.8% to 33.1% and 46.8% to 82.9% (as-is basis), respectively. In vitro ileal disappearance (IVID) of CP was determined and ileal digestible CP content was calculated by multiplying CP content by IVID of CP. In vitro total tract disappearance (IVTTD) of dry matter (DM) was determined and ME was calculated using gross energy, CP contents, and IVTTD of DM. The IVID of CP and IVTTD of DM ranged from 77.2% to 88.7% and from 82.7% to 92.4%, respectively. Calculated ileal digestible CP and ME contents ranged from 37.8% to 73.5% DM and 2,405 to 3,905 kcal/kg DM, respectively. Ash contents were negatively correlated (P < 0.001) with CP (r = −0.99), in vitro ileal digestible CP (r = −0.97), gross energy (r = −1.00), in vitro digestible energy (r = −0.97), and adjusted ME (r = −0.97). The most fitting equations for ileal digestible CP and adjusted ME were: ileal digestible CP (% DM) = 11.91 − 0.90 × Ash (% DM) + 0.74 × IVID of CP (%) (R2 = 0.99) and adjusted ME (kcal/kg DM) = 130.85 − 50.90 × ash (% DM) + 47.06 × IVTTD of DM (%) (R2 = 0.99). To validate the accuracy of the prediction equations for ME, mean bias and linear bias were determined using a regression analysis. Calculated ME values of MM and MBM were in a good agreement with data obtained from animal experiments based on a statistically insignificant bias in the models. In conclusion, ME concentrations of MM and MBM as swine feed ingredients can be calculated using ash concentration and in vitro disappearance of dry matter. 相似文献
114.
115.
运用ANSYS的优化设计模块对永磁电机转子冲片隔磁桥附近的结构进行优化设计,采用APDL参数化设计通过拓扑形状优化功能确定冲片优化的初始区域,在此基础上运用尺寸优化功能确定最优的形状尺寸参数,最终结合工程化要求确定转子冲片的施工结构尺寸。电机最后通过最高转速试验表明文章运用的结构优化设计方法切实可行,满足工程化生产要求。 相似文献
116.
机采棉技术是一项优质、高产、高效的综合机械化技术,大力推广机采棉技术,不仅解决了拾花难这一难题;而且提高了工作效率,降低了生产成本,实现了节本增效;使我区机采棉技术走上规模化生产、专业化管理、集约化发展道路。 相似文献
117.
Yeon Soo Chung Jae Won Song Dae Ho Kim Sook Shin Young Kyung Park Soo Jin Yang Suk Kyung Lim Kun Taek Park Yong Ho Park 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(2):199-206
Limited information is available regarding horse-associated antimicrobial resistant (AR) Escherichia (E.) coli. This study was designed to evaluate the frequency and characterize the pattern of AR E. coli from healthy horse-associated samples. A total of 143 E. coli (4.6%) were isolated from 3,078 samples collected from three national racetracks and 14 private horse-riding courses in Korea. Thirty of the E. coli isolates (21%) showed antimicrobial resistance to at least one antimicrobial agent, and four of the AR E. coli (13.3%) were defined as multi-drug resistance. Most of the AR E. coli harbored AR genes corresponding to their antimicrobial resistance phenotypes. Four of the AR E. coli carried class 1 integrase gene (intI1), a gene associated with multi-drug resistance. Pulsed-field gel electrophoretic analysis showed no genetic relatedness among AR E. coli isolated from different facilities; however, cross-transmissions between horses or horses and environments were detected in two facilities. Although cross-transmission of AR E. coli in horses and their environments was generally low, our study suggests a risk of transmission of AR bacteria between horses and humans. Further studies are needed to evaluate the risk of possible transmission of horse-associated AR bacteria to human communities through horse riders and horse-care workers. 相似文献
118.
Jee-Hoon Lee Ik-Jae Kang A-Reum Kim You-Sun Noh Hee-Chun Chung Bong-Kyun Park 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(2):253-256
This study was conducted to determine if humoral antibody response of foot-and-mouth disease (FMD) vaccine improved in 8-week-old growing pigs born to well-vaccinated sows pre-treated with 60 mg of poly-γ-glutamic acid (γ-PGA) three days before vaccination. Antibody against FMD virus serotype O was measured 0, 2, 4 and 6 weeks post-vaccination, using a PrioCHECK FMDV type O ELISA kit. The results showed that positive antibody reactions against FMDV serotype O antigen among a component of the vaccine significantly increased in response to pre-injection with γ-PGA. 相似文献
119.
Alisha Wehdnesday Bernardo Reyes Hannah Leah Tadeja Simborio Huynh Tan Hop Lauren Togonon Arayan Suk Kim 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(1):119-122
The Brucella mdh gene was successfully cloned and expressed in E. coli. The purified recombinant malate dehydrogenase protein (rMDH) was reactive to Brucella-positive bovine serum in the early stage, but not reactive in the middle or late stage, and was reactive to Brucella-positive mouse serum in the late stage, but not in the early or middle stage of infection. In addition, rMDH did not react with Brucella-negative bovine or mouse sera. These results suggest that rMDH has the potential for use as a specific antigen in serological diagnosis for early detection of bovine brucellosis. 相似文献
120.
Toru TACHIBANA Ken Takeshi KUSAKABE Sayuri OSAKI Takeshi KURAISHI Shosaku HATTORI Midori YOSHIZAWA Chieko KAI Yasuo KISO 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2016,78(1):161-165
The New World monkey Aotus spp. (night monkeys) are expected
for use of valuable experimental animal with the close species of Saimiri
spp. (squirrel monkeys). Saimiri is known to show spontaneous
hypercortisolemia, although few reports in Aotus. We compared basic
states of blood steroid hormones and histological structure of the adrenal glands in two
monkeys. Serum cortisol and ACTH levels were statistically lower in Aotus
than Saimiri. Conversely, Aotus adrenocortical area
showed significant enlargement, especially at the zona fasciculata. Electron microscopic
observation at Aotus fasciculata cells revealed notable accumulation of
large lipid droplets and irregular shapes of the mitochondrial cristae. These results
suggest potential differences in cellular activities for steroidogenesis between
Aotus and Saimiri and experimental usefulness in
adrenocortical physiology and pathological models. 相似文献