全文获取类型
收费全文 | 1425篇 |
免费 | 89篇 |
国内免费 | 1篇 |
专业分类
林业 | 95篇 |
农学 | 91篇 |
基础科学 | 3篇 |
226篇 | |
综合类 | 58篇 |
农作物 | 223篇 |
水产渔业 | 128篇 |
畜牧兽医 | 582篇 |
园艺 | 21篇 |
植物保护 | 88篇 |
出版年
2023年 | 9篇 |
2022年 | 30篇 |
2021年 | 36篇 |
2020年 | 31篇 |
2019年 | 39篇 |
2018年 | 52篇 |
2017年 | 48篇 |
2016年 | 45篇 |
2015年 | 57篇 |
2014年 | 64篇 |
2013年 | 89篇 |
2012年 | 115篇 |
2011年 | 125篇 |
2010年 | 80篇 |
2009年 | 55篇 |
2008年 | 92篇 |
2007年 | 92篇 |
2006年 | 79篇 |
2005年 | 62篇 |
2004年 | 64篇 |
2003年 | 52篇 |
2002年 | 56篇 |
2001年 | 30篇 |
2000年 | 20篇 |
1999年 | 9篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1967年 | 4篇 |
1966年 | 9篇 |
1965年 | 4篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1952年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有1515条查询结果,搜索用时 15 毫秒
111.
Tae Hwan Jun Min Ji Kim Sungyoun Kim Young Hwa Jung Hak-Ryong Moon Kwang-Soo Kim 《Water, air, and soil pollution》2017,228(3):110
Activated carbon-coated electrode was developed and applied in electrostatic precipitator to remove volatile organic compound gases simultaneously with dust particles from a contaminated air. The activated carbon coating mixture was made up of powdered activated carbon (AC), carbon black (CB), and polyvinyl acetate (PVA), and methanol was added as a solvent to control the thickness of the mixture for best coating performance. During the coating process, the Brunauer-Emmett-Teller (BET) surface decreased to 86% of the original AC while pore volume percentages of macro pore increased, compared to micro- and meso-sized pores. The adsorption isotherm of benzene, toluene, ethyl benzene, and xylene (BTEX) gases onto the original AC and AC coating mixture (AC thoroughly mixed with PVA and methanol for coating and powdered again after dry) were tested and compared to each other, and it was found that both isotherm were best fitted to Freundlich and Langmuir isotherm with the order of adsorption capacities; ethyl benzene?>?m-xylene?>?toluene?>?benzene. The difference between adsorption capacities was clearer with the absorbent AC but became little with the AC coating mixture. In removing BTEX at increasing linear velocities up to 6.7 cm/s, it appeared that the surface area of AC electrode was directly proportional to its removal rate of BTEX. The thermal desorption was applied to regenerate the AC electrode, and 200 °C was found to be most efficient for benzene desorption, but higher temperature would be required for entire BTEX gases desorption. 相似文献
112.
Influence of cyto‐sterility sources of female line on seed quality of Indian mustard (Brassica juncea L. Czern & Coss.) in relation to storage period 下载免费PDF全文
Effect of cyto‐sterility sources on morphology and yield attributes in F1 has well been studied in different crops, but not on the seed quality of hybrid. Six cytoplasmic male sterile (CMS) lines, viz. Ogura, Siifolia, Erucoides, Moricandia, Tournefortii and Oxyrrhina, which represent six different sources of CMS, were pollinated by a single maintainer line (‘Pusa Bold’) to check whether CMS sources have any marked effect on seed quality. Seeds were collected in 2007–2008 (rabi season: October–April) from CMS maintenance plot and kept in ambient storage for next 3 years. The results indicated that CMS/cyto‐sterility sources influenced the seed quality parameters in fresh seed as well as after storage. Per cent germination (as means over the storage period) was recorded up to 89.00, 88.25 and 87.88 in Moricandia, Ogura and Oxyrrhina systems, respectively, and it was significantly different from Tournefortii and ‘Pusa Bold’ (70.13 and 74.38, respectively). The CMS sources also had pronounced effect on other seed quality traits, viz. root and shoot length and seedling dry matter, and Ogura and Moricandia (green) performed better. 相似文献
113.
MH Chen SH Choi N Kozukue HJ Kim M Friedman 《Journal of agricultural and food chemistry》2012,60(36):9151-9161
We determined the phenolic, anthocyanin, and proanthocyanidin content of three brown, purple, and red rice brans isolated from different rice varieties using HPLC-PDA with the aid of 27 standards of known structure and matching unknown peaks to a spectral library of known compounds. Antioxidative capacities were determined by DPPH and ORAC and cell-inhibiting effects using an MTT assay. Based on the calculated IC(50) values, the light-brown bran had no effect, the purple bran exhibited a minor effect on leukemia and cervical cancer cells, and the red bran exhibited strong inhibitory effects on leukemia, cervical, and stomach cancer cells. High concentrations of protocatechuic acid and anthocyanins in purple bran and proanthocyanidins in red bran were identified. The red bran was further fractionated on a Sephadex column. Fraction 3 rich in proanthocyanidin oligomers and polymers had the greatest activity. Red bran has the potential to serve as a functional food supplement for human consumption. 相似文献
114.
Modulations of the Bcl-2/Bax family were involved in the chemopreventive effects of licorice root (Glycyrrhiza uralensis Fisch) in MCF-7 human breast cancer cell 总被引:10,自引:0,他引:10
Jo EH Hong HD Ahn NC Jung JW Yang SR Park JS Kim SH Lee YS Kang KS 《Journal of agricultural and food chemistry》2004,52(6):1715-1719
Recently, cancer chemoprevention with strategies using foods and medicinal herbs has been regarded as one of the most visible fields for cancer control. Genistein in soy, American ginseng, and resveratrol are well-known to have antiproliferative properties in human breast cancer. Licorice root is a botanical, a shrub native to southern Europe and Asia, which primarily has desirable qualities in sweetening and herbal medicine. In this study, licorice (Glycyrrhiza uralensis Fisch) root also inhibits cell proliferation in human breast cancer cell. The cell proliferation study demonstrated that licorice root reduced the proliferation of MCF-7 cells in a dose- and time-dependent manner. The extracts were fractionated in CHCl(3), EtOAc, C(6)H(14), and CH(3)OH-H(2)O (70:30), and these extracts of licorice root (50 microg/mL) induced DNA fragmentation demonstrated by Hoechst 33258 staining. Apoptosis also determined the sub-G1 accumulation by flow cytometry analysis. These results were consistent with specific cleavage of PARP and antiapoptotic protein Bcl-2 and up-regulation of proapoptotic protein Bax demonstrated by Western blotting. Our findings suggest that licorice root may have chemopreventive effects against human breast cancer through the modulation of the expression of the Bcl-2/Bax family of apoptotic regulatory factors. 相似文献
115.
Chulkyu Lee Young Joon Kim Sang-Bum Hong Hanlim Lee Jinsang Jung Yeo-Jin Choi Jungeun Park Ki-Hyun Kim Jai-Hoon Lee Ki-Joon Chun Hyun-Ho Kim 《Water, air, and soil pollution》2005,160(1-4):181-195
Ozone effects on Mediterranean forests were studied for 10 years in southern France. The aim of these studies was to understand the impact of the pollutant on foliar damage among Aleppo pine (Pinus halepensis Mill) and Arolla pine (Pinus cembra L) populations. During the summers of 2001 and 2002, ozone concentrations were measured using UV absorption analysers (4) and passive samplers (29) at two forest monitoring sites: Site 1 in the Nice coastal area for Aleppo pine and Site 2 in the Mercantour mountains for Arolla pine, in the vicinity of tree observation sites. AOT 40 values were quite high (25–33 ppm.h), especially in the Mercantour mountains, for the 5 months of measurement. Foliar damage (defoliation and discoloration) and specific symptoms (chlorotic mottle) were observed on 8 Aleppo pine and 13 Arolla pine plots. For Arolla pines, there was a significant correlation between defoliation and chlorotic mottles. There was also a correlation between mean ozone concentrations measured by passive samplers and chlorotic mottles. These correlations were less significant for Aleppo pine. 相似文献
116.
The gradual closure of the Panamanian seaway and the resulting environmental change stimulated an increase in Caribbean molluscan diversity rather than the mass extinction hypothesized previously on the basis of inadequate data. Upheaval of molluscan faunas did occur suddenly throughout tropical America at the end of the Pliocene as a result of more subtle, unknown causes. There is no necessary correlation between the magnitude of regional shifts in abiotic conditions and the subsequent biological response. 相似文献
117.
Ryan R. Busby Robyn A. Barbato Carina M. Jung Kate A. Morozova Anthony J. Bednar Andrew L. Bray Jenifer M. Milam Jared C. Smith Karl J. Indest 《Water, air, and soil pollution》2018,229(12):380
Permafrost thaw is expected to alter biogeochemistry and hydrology, potentially increasing the mobility of soil constituents. Northern latitude boreal forests where permafrost thaw is occurring also experience extreme changes in day length during the growing season. As the effects of photoperiod on plant uptake of soil constituents or interactions with the rhizosphere are unknown, our objective was to determine these interactions with three plant species from different functional groups. A tree, forb, and grass common to military training ranges in this region were grown in soil spiked with or without lead, antimony, or 2,4-dinitrotoluene and grown under 16, 20, or 24 h of light. Plant biomass, soil constituent uptake, and rhizosphere bacterial communities were compared between treatments. Photoperiod had no effect on plant uptake of any soil constituent or on rhizosphere community, indicating that plants and their associated microbial communities adapted to this environment are resilient to extremes in photoperiod. Lead uptake was not significant in any plant species and had no effect on the rhizosphere. Antimony increased the percentage composition of Saprospirales in the rhizospheres of two of the three plants, indicating an interaction between this bacterial order and antimony. Antimony uptake by white spruce (Picea glauca) was considerable, with a mean concentration of 1731 mg kg?1 in roots, while mean shoot concentration was only 155 mg kg?1, indicating its potential to phytostabilize this heavy metal. Although antimony had the strongest impact on the rhizosphere bacterial community, it was also readily accumulated by the grass and tree. 相似文献
118.
Min‐Jung GU Md. Jahangir ALAM Seon‐Ho KIM Che‐Ok JEON Moon‐Baek CHANG Young‐Kyoon OH Sang‐Cheol LEE Sang‐Suk LEE 《Animal Science Journal》2011,82(5):663-672
Molecular diversity of methanogens in the rumen of Korean black goats was investigated with 16S rRNA gene clone libraries using methanogen‐specific primers. The libraries were composed of rumen fluid‐associated methanogens (FAM) and rumen particle‐associated methanogens (PAM) from rumen‐fistulated Korean black goats. Among the 141 clones of the FAM library, the sequences were mostly related to two phyla, the Methanobacteriaceae family (77.3%) and the Thermoplasmatales family (22.7%); and among the 68 clones of the PAM library, sequences were also mainly clustered in the two phyla, the Thermoplasmatales family (63.24%) and the Methanobacteriaceae family (35.29%). Most of the sequenced clones in the two libraries were closely related to uncultured methanogenic archaeon. Quantitative real‐time PCR revealed that PAM (8.97 log 10) had significantly higher (P < 0.01) density of methanogens by the methanogenic 16S rRNA gene copies than FAM (7.57 log 10). The two clone libraries also showed difference in Shannon index (FAM library 1.70 and PAM library 1.59) and Chao 1 estimator (FAM library 18 and PAM library 17 operational taxonomic units). Apparent differences found in the microbial community from the two 16S rRNA gene libraries could be a result of such factors as the chemical and physical nature of the target material surface, types or component of diets, the interaction between the methanogens and other microbes, and age of the experimental goats. 相似文献
119.
Kim DO Heo HJ Kim YJ Yang HS Lee CY 《Journal of agricultural and food chemistry》2005,53(26):9921-9927
The identification of phenolics from various cultivars of fresh sweet and sour cherries and their protective effects on neuronal cells were comparatively evaluated in this study. Phenolics in cherries of four sweet and four sour cultivars were extracted and analyzed for total phenolics, total anthocyanins, and their antineurodegenerative activities. Total phenolics in sweet and sour cherries per 100 g ranged from 92.1 to 146.8 and from 146.1 to 312.4 mg gallic acid equivalents, respectively. Total anthocyanins of sweet and sour cherries ranged from 30.2 to 76.6 and from 49.1 to 109.2 mg cyanidin 3-glucoside equivalents, respectively. High-performance liquid chromatography (HPLC) analysis revealed that anthocyanins such as cyanidin and peonidin derivatives were prevalent phenolics. Hydroxycinnamic acids consisted of neochlorogenic acid, chlorogenic acid, and p-coumaric acid derivatives. Glycosides of quercetin, kaempferol, and isorhamnetin were also found. Generally, sour cherries had higher concentrations of total phenolics than sweet cherries, due to a higher concentration of anthocyanins and hydroxycinnamic acids. A positive linear correlation (r2 = 0.985) was revealed between the total anthocyanins measured by summation of individual peaks from HPLC analysis and the total anthocyanins measured by the pH differential method, indicating that there was in a close agreement with two quantifying methods for measuring anthocyanin contents. Cherry phenolics protected neuronal cells (PC 12) from cell-damaging oxidative stress in a dose-dependent manner mainly due to anthocyanins. Overall results showed that cherries are rich in phenolics, especially in anthocyanins, with a strong antineurodegenerative activity and that they can serve as a good source of biofunctional phytochemicals in our diet. 相似文献
120.
The sponge cake baking test is accepted and routinely used as a standard quality evaluation tool of soft white wheat for Asian markets, but its lengthy and laborious procedure makes it unsuitable for the routine evaluation of a large number of wheat breeding lines. We simplified the sponge cake baking procedure in the egg‐whipping step and improved its consistency by replacement of the hand mixing of cake batter with mechanical mixing, using a wire whisk or a BeaterBlade paddle. Egg whipping and mechanical batter mixing conditions were optimized by comparing foam density, sponge cake volume, and crumb grain to those obtained by the conventional procedure. Foam density, sponge cake volume, and crumb grain comparable to the conventional 100 g flour procedure were obtained with modifications, including extension of whipping time without heat input using a 5 L KitchenAid mixer, one‐time water addition at 3 min before the completion of egg whipping instead of twice, as in the conventional procedure, and cake batter mixing with a KitchenAid wire whisk or a BeaterBlade paddle. For baking a 50 g flour cake, egg foam of appropriate density was obtained with increased whipping speed and shortened egg‐whipping time (8 min). The modified sponge cake baking procedure yielded egg‐foam density, cake volume, and crumb grain similar to the conventional procedure and effectively differentiated soft wheat flours of different quality. Sponge cake volume of 14 soft white wheat flours ranged from 1,134 to 1,426 mL with the conventional procedure, from 1,113 to 1,333 mL with the modified procedure of batter mixing with a wire whisk, from 1,108 to 1,360 mL with the modified procedure of batter mixing with a BeaterBlade paddle, and from 577 to 719 mL with the modified method of 50 g of flour and batter mixing with a wire whisk. The modified methods with the BeaterBlade paddle and wire whisk exhibited significant correlation in cake volume with a conventional procedure (r = 0.931, P < 0.001 and r = 0.925, P < 0.001, respectively). 相似文献