全文获取类型
收费全文 | 2017篇 |
免费 | 127篇 |
国内免费 | 5篇 |
专业分类
林业 | 152篇 |
农学 | 291篇 |
基础科学 | 53篇 |
263篇 | |
综合类 | 77篇 |
农作物 | 406篇 |
水产渔业 | 178篇 |
畜牧兽医 | 426篇 |
园艺 | 113篇 |
植物保护 | 190篇 |
出版年
2024年 | 3篇 |
2023年 | 40篇 |
2022年 | 23篇 |
2021年 | 80篇 |
2020年 | 109篇 |
2019年 | 60篇 |
2018年 | 91篇 |
2017年 | 139篇 |
2016年 | 111篇 |
2015年 | 104篇 |
2014年 | 173篇 |
2013年 | 231篇 |
2012年 | 73篇 |
2011年 | 62篇 |
2010年 | 100篇 |
2009年 | 94篇 |
2008年 | 51篇 |
2007年 | 82篇 |
2006年 | 67篇 |
2005年 | 75篇 |
2004年 | 52篇 |
2003年 | 27篇 |
2002年 | 37篇 |
2001年 | 50篇 |
2000年 | 25篇 |
1999年 | 50篇 |
1998年 | 31篇 |
1997年 | 24篇 |
1996年 | 21篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1989年 | 8篇 |
1988年 | 13篇 |
排序方式: 共有2149条查询结果,搜索用时 78 毫秒
81.
《Postharvest Biology and Technology》2007,46(3):372-380
Use of soft X-ray digital imaging for non-destructive quality evaluation of pecans was explored. Unshelled pecans were imaged at various X-ray tube voltages from 15 to 50 kVp and currents from 0.1 to 1 mA. Pecan images with good contrast image were identified. The cavity inside the pecan shell and the nutmeat portion were segmented manually in the pecan radiographs. Percent nutmeat area, mean pixel intensity, and local intensity variation adequately determined nutmeat quality, non-destructively. Pecan nutmeat weight was estimated with an error of less than 10% from images taken at 35 kVp–0.75 mA, 40 kVp–0.5 mA, and 45 kVp–0.5 mA. Defects and insects were clearly differentiated in X-ray images after applying contrast stretching or high-frequency emphasis techniques. 相似文献
82.
83.
《Applied soil ecology》2007,35(2-3):250-257
Under microcosm conditions, changes in the soil microbial biomass, respiration rates, and nitrogen pools as indicators of potential non-target effects of entomopathogenic nematodes on soil, were evaluated. Two tests were conducted using soil collected from the field with no history of entomopathogenic nematode application. Treatments consisted of applications of Steinernema carpocapsae All strain in the presence or absence of the wax moth Galleria mellonella larva as a target insect host, compared with the untreated control (soil only). In the second experiment an insecticide treatment (trichlorfon) was added. Microbial biomass (total nitrogen), and mineral nitrogen (NH4-N, NO3-N) were measured using standard methods up to 32 days and soil respiration up to 64 days in both experiments. No negative effect was detected in the soil microbial biomass, respiration and nitrogen pools after application of S. carpocapsae. However, a significant increase in ammonium was measured during almost the entire period of the test in the nematode plus larva treatment, not shown in the other treatments. This high level of ammonium in the nematode plus larva treatment showed that entomopathogenic nematodes can indirectly affect system-level processes in soil and adds evidence on the importance of indirect interactions affecting functions in soil food webs. The application of the insecticide trichlorfon significantly suppressed the microbial biomass and nitrification process. 相似文献
84.
Mugerwa Habibu Colvin John Alicai Titus Omongo Christopher A. Kabaalu Richard Visendi Paul Sseruwagi Peter Seal Susan E. 《Journal of pest science》2021,94(4):1307-1330
Journal of Pest Science - Over the past three decades, highly increased whitefly (Bemisia tabaci) populations have been observed on the staple food crop cassava in eastern Africa and associated... 相似文献
85.
In Su Cheon Sung-Moo Park Hye Jin Lee Ji Eun Hong Sang Yun Ji Byoung-Shik Shim Kwang Ho Kim Pil Seung Heo Yoo Yong Kim Hyun Jung Jung Hakhyun Ka Seung Hyun Han Manki Song Cheol-Heui Yun 《Research in veterinary science》2014
In human or mouse, mature T cells express either CD4 or CD8, resulting in different functions in the periphery. Interestingly, porcine CD4 and CD8 double positive (DP) T cells are present in the blood, and their proportions change from youth to adulthood. However, the features of these cells in swine are poorly understood. We investigated the fate of porcine peripheral T cells based on their functional characteristics, including proliferation and the expression of CD4 and CD8 co-receptors. The results showed that all the populations changed their CD8 expression in a time-dependent manner and porcine T cells had different proliferative pattern from human T cells. The results further revealed that Th2 cytokines were increased later in porcine T cells compared to human T cells upon stimulation with IL-2 + PMA. Collectively, we found that the fate of porcine peripheral T cells is different from that of human T cells, and the changes occur in a time- and stimulation-dependent manner. 相似文献
86.
《Veterinary microbiology》2014,168(1):88-97
To compare the pathogenicity of PPMV-1 in pigeons and chickens, both species of birds were experimentally infected with strain pi/CH/LHLJ/110822, which was isolated from a pigeon in China. The clinical signs, gross lesions, and histopathological changes were observed in pigeons inoculated with pi/CH/LHLJ/110822. The morbidity and mortality rates were 80% and 70% in pigeons, respectively, whereas there were no clinical signs or gross lesions in chickens inoculated with the same strain. The viral loads in tissue samples were detected by real-time RT-PCR, indicating that six tissue samples (i.e., kidney, lung, brain, trachea, Harderian glands, and proventriculus) had detectable viral RNA in all dead pigeons, and significant differences in viral loads between pigeons and chickens were observed in several tissue samples (i.e., Harderian glands, proventriculus, duodenum, pancreas, small intestine, and large intestine) on 3 days post-inoculation (dpi) and in brain tissue on 7 dpi. In general, viral loads in pigeons were higher than those in chickens, whereas antibody titers in pigeons were lower than those in chickens. These results showed differences in pathogenicity, efficiency of viral RNA replication, and humoral immunity, indicating different susceptibilities between the host species. Additionally, the cross hemagglutination inhibition assay and cross virus neutralization tests demonstrated that pi/CH/LHLJ/110822 antigenicity was different from those of strains La Sota and F48E9. 相似文献
87.
《Journal of Equine Veterinary Science》2014,34(11-12):1348-1351
A case of encephalitis of unknown origin in the horse was investigated. Postmortem examination findings revealed a nonsuppurative granulomatous meningoencephalitis in the right hemisphere of the cerebral cortex. Testing for West Nile virus, equine herpes virus, equine infectious anemia, Toxoplasma gondii, Neospora caninum, and Sarcocystis neurona were negative. The horse had a titer for Encephalitozoon cuniculi, and sections from the affected area of the brain tested positive for the organism using both polymerase chain reaction (PCR) and immunohistochemistry. Amplicons generated using PCR were sequenced, and E. cuniculi genotype II was identified. This is the first case of E. cuniculi genotype II associated with encephalitis in the horse. 相似文献
88.
《Journal of Equine Veterinary Science》2014,34(11-12):1357-1360
ReGeneraTing Agents (RGTA) are nanopolysaccharides engineered to mimic heparan sulfates and have been shown to stimulate tissue repair and healing (skin, cornea, gingival, and muscle) in several animal models of injury and in human medicine. A preliminary study, monocentric and uncontrolled, was conducted to evaluate the efficacy of a dedicated RGTA (named Equitend) in improving the healing quality of the injured tendon after a single and ultrasound-guided intralesional injection. Improvement of ultrasonographic appearance of tendinous or ligamentous lesion was documented at least over 4 months in Equitend-treated horses and was further supported by another study on superficial digital flexor tendonitis, in 51 horses (16 French Standardbred trotters (ST), 13 Thoroughbreds (TB), and 22 eventers). Long-term follow-up of these horses showed high rates of return to racing, with 95% of eventers, 87.5% of French ST, and 77% of TB. The mean duration before the first race or competition was 6.6 and 7.4 months for ST and eventers, respectively. The group of 16 treated ST was then compared with a matched control group, showing that the Equitend-treated group was able to return to a higher level of earning after lesion (74% vs. 15% in the control group). Furthermore, the Equitend-treated group was back in racing 2.4 months earlier than the control group. 相似文献
89.
《Aquaculture (Amsterdam, Netherlands)》2006,251(2-4):219-230
Developmental genetic analysis was conducted for body weight, total length, standard length and body height in red common carp by a mixed genetic model with additive–dominance effects, based on complete diallel crosses made by Xingguo red common carp (Cyprinus carpio var. singuonensis), purse red common carp (Cyprinus carpio var. wuyuanensis) and Oujiang color common carp (Cyprinus carpio var. color). Unconditional genetic analysis revealed that the traits of body weight, total length and standard length were mainly controlled by dominance effects before June but by additive effects after June, which suggests a high potential for heterosis during the early developmental period and an opportunity for selection during the late developmental periods for common carp. Through conditional genetic analysis, lots of new expression of genes of additive effects for body weight, total length and standard length existed during April to August and significant new expression of genes from dominance effects for these three traits at the other period. New expression from additive and dominance effect genes for body height occurred intermittently during the ontogeny. The conditional genetic procedure is a useful tool to understand the expression of genes controlling developmental quantitative traits at a specific developmental period (t − 1 → t) during ontogeny. It is also important to determine the appropriate developmental period (t − 1 → t) for trait measurement in developmental quantitative genetic analysis in fish. 相似文献
90.
R. Carnwath E.M. Graham K. Reynolds P.J. Pollock 《Veterinary journal (London, England : 1997)》2014,199(1):110-114
Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and non-irradiated commercial medical grade honeys, supermarket honeys, and honeys from local beekeepers. To exclude contaminated honeys from the project, all honeys were cultured aerobically for evidence of bacterial contamination. Aerobic bacteria or fungi were recovered from 18 products. The antimicrobial activity of the remaining 11 products was assessed against 10 wound bacteria, recovered from the wounds of horses, including methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. Eight products were effective against all 10 bacterial isolates at concentrations varying from <2% to 16% (v/v). Overall, the Scottish Heather Honey was the best performing product, and inhibited the growth of all 10 bacterial isolates at concentrations ranging from <2% to 6% (v/v).Although Manuka has been the most studied honey to date, other sources may have valuable antimicrobial properties. Since some honeys were found to be contaminated with aerobic bacteria or fungi, non-sterile honeys may not be suitable for wound treatment. Further assessment of gamma-irradiated honeys from the best performing honeys would be useful. 相似文献