全文获取类型
收费全文 | 2021篇 |
免费 | 99篇 |
专业分类
林业 | 51篇 |
农学 | 58篇 |
基础科学 | 3篇 |
336篇 | |
综合类 | 286篇 |
农作物 | 252篇 |
水产渔业 | 142篇 |
畜牧兽医 | 861篇 |
园艺 | 25篇 |
植物保护 | 106篇 |
出版年
2022年 | 23篇 |
2021年 | 38篇 |
2020年 | 23篇 |
2019年 | 26篇 |
2018年 | 52篇 |
2017年 | 45篇 |
2016年 | 45篇 |
2015年 | 44篇 |
2014年 | 56篇 |
2013年 | 109篇 |
2012年 | 101篇 |
2011年 | 137篇 |
2010年 | 61篇 |
2009年 | 51篇 |
2008年 | 96篇 |
2007年 | 107篇 |
2006年 | 64篇 |
2005年 | 77篇 |
2004年 | 72篇 |
2003年 | 72篇 |
2002年 | 51篇 |
2001年 | 33篇 |
2000年 | 43篇 |
1999年 | 37篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1994年 | 14篇 |
1992年 | 26篇 |
1991年 | 39篇 |
1990年 | 33篇 |
1989年 | 29篇 |
1988年 | 20篇 |
1987年 | 28篇 |
1986年 | 27篇 |
1985年 | 27篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 19篇 |
1976年 | 11篇 |
1974年 | 17篇 |
1973年 | 23篇 |
1972年 | 18篇 |
1971年 | 14篇 |
1970年 | 18篇 |
1969年 | 19篇 |
1968年 | 12篇 |
1966年 | 11篇 |
排序方式: 共有2120条查询结果,搜索用时 15 毫秒
141.
Lee KW Kim YJ Kim DO Lee HJ Lee CY 《Journal of agricultural and food chemistry》2003,51(22):6516-6520
The contribution of each phytochemical to the total antioxidant capacity of apples was determined. Major phenolic phytochemicals of six apple cultivars were identified and quantified, and their contributions to total antioxidant activity of apples were determined using a 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay and expressed as vitamin C equivalent antioxidant capacity (VCEAC). Average concentrations of major phenolics and vitamin C in six apple cultivars were as follows (mg/100 g of fresh weight of apples): quercetin glycosides, 13.20; procyanidin B(2), 9.35; chlorogenic acid, 9.02; epicatechin, 8.65; phloretin glycosides, 5.59; vitamin C, 12.80. A highly linear relationship (r (2) > 0.97) was attained between concentrations and total antioxidant capacity of phenolics and vitamin C. Relative VCEAC values of these compounds were in the order quercetin (3.06) > epicatechin (2.67) > procyanidin B(2) (2.36) > phloretin (1.63) > vitamin C (1.00) > chlorogenic acid (0.97). Therefore, the estimated contribution of major phenolics and vitamin C to the total antioxidant capacity of 100 g of fresh apples is as follows: quercetin (40.39 VCEAC) > epicatechin (23.10) > procyanidin B(2) (22.07) > vitamin C (12.80) > phloretin (9.11) > chlorogenic acid (8.75). These results indicate that flavonoids such as quercetin, epicatechin, and procyanidin B(2) rather than vitamin C contribute significantly to the total antioxidant activity of apples. 相似文献
142.
143.
Young JF Rosenvold K Stagsted J Steffensen CL Nielsen JH Andersen HJ 《Journal of agricultural and food chemistry》2003,51(23):6877-6881
Polyunsaturated fatty acids (PUFAs) and exercise-induced stress are known to increase the oxidative susceptibility of lipids in muscle tissue. In contrast, antioxidative enzymes, e.g., catalase, superoxide dismutase, and glutathione peroxidase, are known to help sustain the delicate oxidative balance in biological tissue upon the application of stressors. The present study investigates the combined effect of different diet-induced muscle PUFA contents and preslaughter stress on the activity of antioxidative muscle enzymes and the oxidative stability of cooked meat. An increased content of unsaturated fatty acids in the tissue led to a decreased activity of lactate dehydrogenase in the plasma, indicating increased cell integrity. Catalase activity in the muscle tissue increased with increasing PUFA levels. However, this upregulation in antioxidative status of the muscle could not counteract the subsequent development of accelerated lipid oxidation in cooked meat as measured in terms of thiobarbituric acid reactive substances. Moreover, preslaughter stress induced increasing oxidative changes with elevated PUFA levels in the muscle tissue. 相似文献
144.
M L Young 《Journal of the Association of Official Analytical Chemists》1984,67(5):1022-1024
A reliable method has been developed for the rapid separation and identification of the 7 permitted FD&C dyes (Red Nos. 3 and 40; Blue Nos. 1 and 2; Yellow Nos. 5 and 6; Green No. 3) and the recently banned FD&C Red No. 2 in foods. The colors are separated by using the C18 cartridge, and their identity is confirmed by spectrophotometry. 相似文献
145.
Weixian Liu Moon Young Kim Kyujung Van Yeong-Ho Lee Hulin Li Xianhu Liu Suk-Ha Lee 《Journal of Crop Science and Biotechnology》2011,14(1):65-70
Two soybean recombinant inbred line populations, Jinpumkong 2 × SS2-2 (J × S) and Iksannamulkong × SS2-2 (I x S) showed population-specific
quantitative trait loci (QTLs) for days to flowering (DF) and days to maturity (DM) and these were closely correlated within
population. In the present study, we identified QTLs for six yield-related traits with simple sequence repeat markers, and
biological correlations between flowering traits and yield-related traits. The yield-related traits included plant height
(PH), node numbers of main stem (NNMS), pod numbers per plant (PNPP), seed numbers per pod (SNPP), 100-seed weight (SW), and
seed yield per plant (SYPP). Eighteen QTLs for six yield-related traits were detected on nine chromosomes (Chrs), containing
four QTLs for PH, two for NNMS, two for PNPP, three for SNPP, five for SW, and two for SYPP. Two highly significant QTLs for
PH and NNMS were identified on Chr 6 (LG C2) in both populations where the major flowering gene, E1, and two DF and DM QTLs were located. One other PNPP QTL was also located on this region, explaining 12.9% of phenotypic
variation. Other QTLs for yield-related traits showed population-specificity. Two significant SYPP QTLs potentially related
with QTLs for SNPP and PNPP were found on the same loci of Chrs 8 (Satt390) and 10 (Sat_108). Also, highly significant positive
phenotypic correlations (P < 0.01) were found between DF with PH, NNMS, PNPP, and SYPP in both populations, while flowering was negatively correlated
with SNPP and SW in the J × S (P < 0.05) and I × S (P < 0.01) populations. Similar results were also shown between DM and yield-related traits, except for one SW. These QTLs identified
may be useful for marker-assisted selection by soybean breeders. 相似文献
146.
Nakashiba T Young JZ McHugh TJ Buhl DL Tonegawa S 《Science (New York, N.Y.)》2008,319(5867):1260-1264
The hippocampus is an area of the brain involved in learning and memory. It contains parallel excitatory pathways referred to as the trisynaptic pathway (which carries information as follows: entorhinal cortex --> dentate gyrus --> CA3 --> CA1 --> entorhinal cortex) and the monosynaptic pathway (entorhinal cortex --> CA1 --> entorhinal cortex). We developed a generally applicable tetanus toxin-based method for transgenic mice that permits inducible and reversible inhibition of synaptic transmission and applied it to the trisynaptic pathway while preserving transmission in the monosynaptic pathway. We found that synaptic output from CA3 in the trisynaptic pathway is dispensable and the short monosynaptic pathway is sufficient for incremental spatial learning. In contrast, the full trisynaptic pathway containing CA3 is required for rapid one-trial contextual learning, for pattern completion-based memory recall, and for spatial tuning of CA1 cells. 相似文献
147.
148.
149.
150.
Young HC 《Science (New York, N.Y.)》1928,67(1723):19-20