全文获取类型
收费全文 | 422篇 |
免费 | 53篇 |
国内免费 | 4篇 |
专业分类
林业 | 21篇 |
农学 | 16篇 |
基础科学 | 2篇 |
96篇 | |
综合类 | 53篇 |
农作物 | 44篇 |
水产渔业 | 123篇 |
畜牧兽医 | 85篇 |
园艺 | 10篇 |
植物保护 | 29篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 25篇 |
2019年 | 20篇 |
2018年 | 29篇 |
2017年 | 26篇 |
2016年 | 27篇 |
2015年 | 19篇 |
2014年 | 20篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 35篇 |
2010年 | 19篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 27篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有479条查询结果,搜索用时 31 毫秒
31.
Antiproliferative and chemopreventive effects of adlay seed on lung cancer in vitro and in vivo 总被引:9,自引:0,他引:9
This study examined the effects of different extracts of adlay seed on the growth of human lung cancer cells in vitro and in vivo. The data showed that a methanolic extract, but not a water extract, of adlay seed exerted an antiproliferative effect on A549 lung cancer cells by inducing cell cycle arrest and apoptosis. It was also found that tumor growth in vivo was inhibited by the methanolic extract in a dose-dependent manner. The chemopreventive effect of adlay seed on the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in A/J mice was also investigated. Groups of mice were pre-fed with different diets, followed by feeding with NNK-containing drinking water for 8 months. The results indicated that feeding with diet containing 30% of powdered adlay seed reduced the number of surface lung tumors by approximately 50%. Taken together, these results indicate that the components of adlay seed exert an anticancer effect in vitro and in vivo and may be useful for the prevention of lung tumorigenesis. 相似文献
32.
The antioxidant activity of phenolic compounds isolated from Mesona procumbens Hemsl. (Hsian-tsao) was investigated. Hsian-tsao was extracted with various solvents, and the results showed that the fraction treated with acidic ethyl acetate (pH 2) possessed large amounts of phenolic compounds and a strong antioxidant activity on peroxidation of linoleic acid. The antioxidant activity (inhibition of peroxidation, IP%) of the acidic ethyl acetate of Hsian-tsao extract at 50 microg/mL (98.9%) was stronger than those of 50 microg/mL alpha-tocopherol (78%) and BHA at 10 microg/mL (90%). When fractionated with Amberlite XAD-7 gel chromatography, the acidic ethyl acetate fraction of Hsian-tsao extract was separated into four subfractions (A-D). Subfraction B, with high yield and strong antioxidant activity, was further isolated and purified and then identified as containing protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, and syringic acid by means of UV, EI-MS, and (1)H and (13)C NMR. The antioxidant capability of isolated compounds was also determined using the thiocyanate system and the erythrocyte ghost system. The results indicate that the phenolic acids could be important antioxidant components in Hsian-tsao, among which caffeic acid with the highest antioxidant activity and the greatest content is most important. 相似文献
33.
Vittadini E Dickinson LC Lavoie JP Pham X Chinachoti P 《Journal of agricultural and food chemistry》2003,51(6):1647-1652
Molecular mobility of water was studied in a microbiological media containing complex and heterogeneous mixtures of cellulose, l-sorbose, and orange serum broth (OSB) using (2)H and (17)O high-resolution NMR. All mixtures showed Lorentian (17)O NMR spectra but complex (2)H NMR line shapes. Sorbose, when solubilized, caused line-narrowing where as cellulose-OSB mixtures showed wide peaks with flat plateaus. Presence of liquid or solvent water had a profound effect on a marked increase in T(2) relaxation time observed in sorbose-containing samples. (17)O NMR data were not composition dependent, while (2)H NMR data were highly sorbose dependent. 相似文献
34.
This paper describes the characteristics of data about wood and wood-processing products published in Vietnam. The characteristics
include inconsistency of data published by major data sources, lack of necessary data, and irregular publication frequency.
Reasons are identified for the existence of the above characteristics of data for the wood and wood-processing industries,
including recent changes in the functions of state statistical organizations and unclear concepts of data published. These
characteristics create difficulties for researchers and policy-makers working at the Ministry of Agriculture and Rural Development
for analysing policies and establishing supply targets for the wood and wood-processing industries in 5-year economic plans.
To improve the statistical system, co-operation between state organisations and the information network (e.g. computers and
internet connection) requires strengthening. 相似文献
35.
Understanding the brain computations leading to object recognition requires quantitative characterization of the information represented in inferior temporal (IT) cortex. We used a biologically plausible, classifier-based readout technique to investigate the neural coding of selectivity and invariance at the IT population level. The activity of small neuronal populations (approximately 100 randomly selected cells) over very short time intervals (as small as 12.5 milliseconds) contained unexpectedly accurate and robust information about both object "identity" and "category." This information generalized over a range of object positions and scales, even for novel objects. Coarse information about position and scale could also be read out from the same population. 相似文献
36.
Pham KN Puertas AM Bergenholtz J Egelhaaf SU Moussaïd A Pusey PN Schofield AB Cates ME Fuchs M Poon WC 《Science (New York, N.Y.)》2002,296(5565):104-106
Experiments, theory, and simulation were used to study glass formation in a simple model system composed of hard spheres with short-range attraction ("sticky hard spheres"). The experiments, using well-characterized colloids, revealed a reentrant glass transition line. Mode-coupling theory calculations and molecular dynamics simulations suggest that the reentrance is due to the existence of two qualitatively different glassy states: one dominated by repulsion (with structural arrest due to caging) and the other by attraction (with structural arrest due to bonding). This picture is consistent with a study of the particle dynamics in the colloid using dynamic light scattering. 相似文献
37.
38.
A new probe for the diagnosis of myotonic muscular dystrophy 总被引:11,自引:0,他引:11
R J Bartlett M A Pericak-Vance L Yamaoka J Gilbert M Herbstreith W Y Hung J E Lee T Mohandas G Bruns C Laberge 《Science (New York, N.Y.)》1987,235(4796):1648-1650
Myotonic muscular dystrophy (DM) is the most common muscular dystrophy, affecting adults as well as children. It is inherited as an autosomal dominant trait and is characterized by variable expressivity and late age-of-onset. Linkage studies have established the locus on chromosome 19. In order to identify tightly linked probes for diagnosis as well as to define in detail the DM gene region, chromosome 19 libraries were constructed and screened for restriction fragment length polymorphisms tightly linked to DM. A genomic clone, LDR152 (D19S19), was isolated that is tightly linked to DM; recombination fraction = 0.0 (95% confidence limits 0.0-0.03); lod score, 15.4. 相似文献
39.
The neu gene: an erbB-homologous gene distinct from and unlinked to the gene encoding the EGF receptor 总被引:45,自引:0,他引:45
A L Schechter M C Hung L Vaidyanathan R A Weinberg T L Yang-Feng U Francke A Ullrich L Coussens 《Science (New York, N.Y.)》1985,229(4717):976-978
The neu oncogene, identified in ethylnitrosourea-induced rat neuroglioblastomas, had strong homology with the erbB gene that encodes the epidermal growth factor receptor. This homology was limited to the region of erbB encoding the tyrosine kinase domain. It was concluded that the neu gene is a distinct novel gene, as it is not coamplified with sequences encoding the EGF receptor in the genome of the A431 tumor line and it maps to human chromosome 17. 相似文献
40.
Magnetic fields (MFs) have been applied for the first time in orchid micropropagation. Protocorm-like bodies (PLBs) – approximately 3 mm in diameter – first derived from leaf segment culture of Phalaenopsis Gallant Beau ‘George Vazquez’, were subcultured every 2 months, and served as initial explants. The proliferation of Phalaenopsis PLBs in liquid medium in the Miracle Pack® culture system was affected by the action of different intensities and polarities of MFs: 0.1, 0.15 and 0.2 Tesla (T) at North (N) and South (S) poles. The MF of 0.1 T – S resulted in the greatest fresh weight of regenerated PLBs. The average number of neo-PLBs formed per clusters in the PLB treated by MF: 0.1–0.2 T was decreased compared to the control exposed to natural MF (5 × 10−6 T). The proliferation of PLBs under 0.15 T – MF at both N and S poles for 2 and 7 weeks demonstrated that a longer duration of exposure to an MF of 0.15 T, regardless of the polarity, resulted in greater biomass of newly formed PLBs and smaller average number of newly formed PLBs. The S pole of MF had stronger effects on Phalaenopsis PLBs proliferation than the N pole did in all treatments. 相似文献