全文获取类型
收费全文 | 525篇 |
免费 | 45篇 |
国内免费 | 3篇 |
专业分类
林业 | 56篇 |
农学 | 17篇 |
基础科学 | 2篇 |
98篇 | |
综合类 | 67篇 |
农作物 | 29篇 |
水产渔业 | 36篇 |
畜牧兽医 | 194篇 |
园艺 | 15篇 |
植物保护 | 59篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 24篇 |
2020年 | 21篇 |
2019年 | 18篇 |
2018年 | 20篇 |
2017年 | 24篇 |
2016年 | 21篇 |
2015年 | 23篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 42篇 |
2011年 | 42篇 |
2010年 | 29篇 |
2009年 | 20篇 |
2008年 | 36篇 |
2007年 | 26篇 |
2006年 | 30篇 |
2005年 | 31篇 |
2004年 | 16篇 |
2003年 | 19篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1960年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有573条查询结果,搜索用时 31 毫秒
1.
The heterogenicity of Cowdria ruminantium stocks: cross-immunity and serology in sheep and pathogenicity to mice 总被引:2,自引:0,他引:2
J L Du Plessis L Van Gas J A Olivier J D Bezuidenhout 《The Onderstepoort journal of veterinary research》1989,56(3):195-201
Ten stocks of Cowdria ruminantium (Ball 3, Breed, Comoro, Germishuys, Kümm, Kwanyanga, Mali, Mara, Nonile and Welgevonden) were compared from a cross-immunity, serological and mouse pathogenicity point of view. They were found to differ in varying degrees. Except for the Ball 3, Comoro and Germishuys stocks that were similar but not identical, there was no pattern in the antigenic diversity of the 10 stocks. The Welgevonden stock emerged as the stock that elicits an immunity against most of the South African stocks. The inability of the reference Ball 3 stock to protect sheep against no fewer than 6 other stocks questions the advisability of retaining this stock as the vaccine stock. The antigenic diversity of the 10 stocks could not be correlated with the antibody levels detected with the indirect fluorescent antibody test, since the sera against all 10 stocks reacted positively to the Kümm stock antigen and the variation in titres was not stock-related. 相似文献
2.
NDeye Lallah Nina Koite Ngouro Issa Sanogo Olivier Lpine Jean-Marie Bard Khadija Ouguerram 《Marine drugs》2022,20(7)
Lipid peroxidation is associated with the development of some pathologies, such as cardiovascular diseases. Reduction in oxidative stress by antioxidants, such as Arthrospira (formely Spirulina), helps improving this redox imbalance. The aim of the study was to evaluate the effect of the Arthrospira liquid extract “Spirulysat®” on oxidative markers—in particular, oxidized LDL (oxLDL)/total LDL cholesterol—and isoprostanes and to investigate its impact on lipid and glucose metabolism in the metabolic syndrome subject. A controlled, randomised, double-blind design was conducted in 40 subjects aged 18 to 65 years with metabolic syndrome after a daily intake of Spirulysat® or placebo for twelve weeks. Blood and urinary samples were collected at three visits (V1, V2, V3) in the two groups for parameters determination. Although the Spirulysat® group showed a decrease at all visits of the oxLDL/total cholesterol ratio, there was no significant difference compared to the placebo (p = 0.36). The urinary isoprostanes concentration in the Spirulysat® group was reduced (p = 0.014) at V3. Plasma triglycerides decreased at V3 (p = 0.003) and HDL-cholesterol increased (p = 0.031) at all visits with Spirulysat®. In conclusion, Spirulysat® did not change the oxidized LDL (oxLDL)/LDL ratio but decreased the urinary isoprostanes, plasma triglycerides and increased HDL cholesterol, suggesting a beneficial effect on metabolic syndrome. 相似文献
3.
At geological time scales, the role of continental erosion in the organic carbon (OC) cycle is determined by the balance between recent OC burial and petrogenic OC oxidation. Evaluating its net effect on the concentration of carbon dioxide and dioxygen in the atmosphere requires the fate of petrogenic OC to be assessed. Here, we report a multiscale (nanometer to micrometer) structural characterization of petrogenic OC in the Himalayan system. We show that graphitic carbon is preserved and buried in marine sediments, while the less graphitized forms are oxidized during fluvial transport. Radiocarbon dating indicates that 30 to 50% of the carbon initially present in the Himalayan rocks is conserved during the erosion cycle. Graphitization during metamorphism thus stabilizes carbon in the crust over geological time scales. 相似文献
4.
Andrea Weissman Mauricio Solano Olivier Taeymans Shannon P. Holmes David Jiménez Bruce Barton 《Veterinary radiology & ultrasound》2016,57(2):124-129
An imaging report is a vital communication tool between a radiologist and clinician. In a field where in‐person communication may not be readily available, it is imperative that the report clearly relays pertinent clinical information in a timely manner. The purpose of this observational study was to describe and compare opinions and expectations of small animal general practitioners, veterinary specialists, and veterinary radiologists regarding the imaging report. Online surveys were distributed, and data were collected from 202 veterinary clinicians and 123 veterinary radiologists. The majority (89%) of clinicians were satisfied with their imaging reports and stated that they read the radiology report as soon as it was available (92%). Just less than half (48%) of clinicians indicated it was standard of care that a board‐certified veterinary radiologist read all imaging studies. Radiologists and clinicians agreed that a clinical history (98% and 94%, respectively) and clinical question (82% and 68%, respectively) were needed to generate a good radiology report. Fifty‐five percent to 70% of clinicians prefer red bulleted reports, which included incidental findings (96%); while radiologists slightly favored prose reporting (37–46%). Clinicians found it helpful when additional imaging (86%), medical (71%), and surgical recommendations (73%) were made. About one‐third of specialists who had been in practice for >11 years thought they were better able to interpret imaging for their own specialty than the radiologist. Clinicians voiced discontentment with reports that were not completed in a timely manner or did not give a prioritized differential list. Further studies are warranted to provide a more in‐depth evaluation of veterinary radiology reporting structure and style. 相似文献
5.
Atherosclerosis is a common disease in pet birds, particularly in psittacines. Little is known about the role of risk factors predisposing birds to this disease. In our study, we tried to detect chlamydiae in formalin-fixed and paraffin-embedded atherosclerotic tissue from 103 pet birds to clarify their role in atherosclerosis. Methods used were polymerase chain reaction (PCR), sequencing, and immunohistochemistry. Histopathologic examination served to classify the extent of atherosclerotic lesions. In the PCR, 4 (3.9%) of 103 cases, all of them with advanced stages of atherosclerosis, were positive. Subsequent sequence analysis revealed high identities (94%-100%) with Chlamydophila psittaci in three cases. Interestingly, two of these birds came from C. psittaci-infected populations. Because of the low incidence (3.9%), the occurrence only in advanced stages, and the association with C psittaci-infected avian populations, a causal relationship between chlamydiae and atherosclerosis in pet birds is rather improbable. 相似文献
6.
Ritter MJ Perry RL Olivier NB Kim SY Dejardin LM 《Journal of the American Animal Hospital Association》2007,43(2):93-98
A novel technique was developed to estimate the caudal medial tibial plateau landmark in the face of osteophytosis to improve accuracy in tibial plateau angle measurements. Using this technique, tibial plateau angles were evaluated in 31 normal dogs before and 8 months after right cranial cruciate ligament transection. There was no significant difference in mean tibial plateau angle before or after induction of osteophytosis. Additionally, it was determined that 90% of dogs had a difference of =2 degrees between right and left tibial plateau angles, which was considered symmetrical. 相似文献
7.
Stanislas Talaga Frédéric Petitclerc Jean-François Carrias Olivier Dézerald Céline Leroy Régis Céréghino Alain Dejean 《Landscape Ecology》2017,32(9):1805-1818
Context
Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem.Objectives
To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape.Methods
Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses.Results
We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator.Conclusions
The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning.8.
9.
Marilia Barreca Virginia Span Alessandra Montalbano Mercedes Cueto Ana R. Díaz Marrero Irem Deniz Ayegül Erdoan Lada Luki Bilela Corentin Moulin Elisabeth Taffin-de-Givenchy Filippo Spriano Giuseppe Perale Mohamed Mehiri Ana Rotter Olivier P. Thomas Paola Barraja Susana P. Gaudêncio Francesco Bertoni 《Marine drugs》2020,18(12)
The marine environment is a rich source of biologically active molecules for the treatment of human diseases, especially cancer. The adaptation to unique environmental conditions led marine organisms to evolve different pathways than their terrestrial counterparts, thus producing unique chemicals with a broad diversity and complexity. So far, more than 36,000 compounds have been isolated from marine micro- and macro-organisms including but not limited to fungi, bacteria, microalgae, macroalgae, sponges, corals, mollusks and tunicates, with hundreds of new marine natural products (MNPs) being discovered every year. Marine-based pharmaceuticals have started to impact modern pharmacology and different anti-cancer drugs derived from marine compounds have been approved for clinical use, such as: cytarabine, vidarabine, nelarabine (prodrug of ara-G), fludarabine phosphate (pro-drug of ara-A), trabectedin, eribulin mesylate, brentuximab vedotin, polatuzumab vedotin, enfortumab vedotin, belantamab mafodotin, plitidepsin, and lurbinectedin. This review focuses on the bioactive molecules derived from the marine environment with anticancer activity, discussing their families, origin, structural features and therapeutic use. 相似文献
10.
Olivier M Aggarwal A Allen J Almendras AA Bajorek ES Beasley EM Brady SD Bushard JM Bustos VI Chu A Chung TR De Witte A Denys ME Dominguez R Fang NY Foster BD Freudenberg RW Hadley D Hamilton LR Jeffrey TJ Kelly L Lazzeroni L Levy MR Lewis SC Liu X Lopez FJ Louie B Marquis JP Martinez RA Matsuura MK Misherghi NS Norton JA Olshen A Perkins SM Perou AJ Piercy C Piercy M Qin F Reif T Sheppard K Shokoohi V Smick GA Sun WL Stewart EA Fernando J Tejeda Tran NM Trejo T Vo NT Yan SC Zierten DL Zhao S 《Science (New York, N.Y.)》2001,291(5507):1298-1302
We have constructed a physical map of the human genome by using a panel of 90 whole-genome radiation hybrids (the TNG panel) in conjunction with 40,322 sequence-tagged sites (STSs) derived from random genomic sequences as well as expressed sequences. Of 36,678 STSs on the TNG radiation hybrid map, only 3604 (9.8%) were absent from the unassembled draft sequence of the human genome. Of 20,030 STSs ordered on the TNG map as well as the assembled human genome draft sequence and the Celera assembled human genome sequence, 36% of the STSs had a discrepant order between the working draft sequence and the Celera sequence. The TNG map order was identical to one of the two sequence orders in 60% of these discrepant cases. 相似文献