全文获取类型
收费全文 | 585篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
616篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 18篇 |
2016年 | 14篇 |
2015年 | 30篇 |
2014年 | 43篇 |
2013年 | 38篇 |
2012年 | 60篇 |
2011年 | 58篇 |
2010年 | 35篇 |
2009年 | 25篇 |
2008年 | 32篇 |
2007年 | 25篇 |
2006年 | 30篇 |
2005年 | 29篇 |
2004年 | 16篇 |
2003年 | 22篇 |
2002年 | 15篇 |
2001年 | 17篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 15 毫秒
121.
Choonsig Kim Kyung-Soo Jang Joon-Bum Kim Jae-Kyung Byun Choong-Hwa Lee Kwon-Seok Jeon 《Landscape and Ecological Engineering》2010,6(1):119-124
This study was conducted to evaluate and compare soil properties between pine stands either damaged or undamaged by pine wilt
disease in Jinju and Sacheon Cities, which are areas in Korea severely affected by the disease. Soil physical and chemical
properties were generally similar between damaged and undamaged pine stands. There was no significant difference in soil factors
related to soil nutrient fertility between damaged and undamaged pine stands, although the incidence of pine wilt disease
was affected by soil clay content, which was significantly (P < 0.05) higher in the damaged (24.8%) than in the undamaged (20.1%) pine stands. However, this relationship should be treated
with caution because small scale topographical variation may simply reflect the incidence of pine wilt disease. The results
suggest that incidence of pine wilt disease was not influenced by soil nutrient properties at a small stand scale. 相似文献
122.
Lipase catalyzed production of monoacylglycerols by the esterification of fish oil fatty acids with glycerol 总被引:1,自引:0,他引:1
Hee-Guk Byun Tae-Kil Eom Won-Kyo Jung Se-Kwon Kim 《Biotechnology and Bioprocess Engineering》2007,12(5):491-496
In this study, we attempted the efficient production of monoacylglycerols (MAG) via the lipase-catalyzed esterification of
glycerol with fatty acids obtained from sardine oil. The reaction factors that influenced MAG synthesis were the glycerol
to fatty acid mole ratio, amount of enzyme, organic solvent, temperature, and the type of lipase used. Porcine pancreas lipase
was selected to catalyze this reaction. The optimum conditions we determined for MAG synthesis were a glycerol to fatty acid
mole ratio of 1∶6, 100 mg/mL of lipase, and 30°C in dioxane. Under these conditions, the MAG content was 68% (w/w) after 72
h of reaction. The MAGs synthesized via the lipase-catalyzed esterification of glycerol with fatty acids included monomyristin,
monopamiltin, and monoolein, as identified by GCMS. 相似文献
123.
Kyung-A Kim Eul-Won Hwang Soo-Chul Park Mi-Jeong Jeong Myung-Ok Byun Hawk-Bin Kwon 《Journal of Plant Biology》2007,50(1):44-49
Zinc finger proteins function in plant tolerances to stresses from cold, dehydration, and salt. To determine the mechanisms
for those underlying defenses, we previously used cDNA microarrays and northern blot analysis to identify a gene for the ring
zinc finger protein (RDCP1) from hot pepper (Capsicum annuum). In that study, we showed that theRDCP1 gene was strongly induced by cold stress and, to a lesser degree, by ABA and high salt Here, we have used a Ti-plasmid andAgrobacterium- mediated transformation to engineerRDCP1 under the control of the CaMV35S promoter for constitutive expression in tobacco. The resultant RDCP1 transgenic plants exhibit
significantly increased tolerance to low temperatures. Moreover, some of those transgenics have greater drought tolerance.
In addition, none of the RDCP1 transgenic plants show any visible alterations from the wild phenotype. These current results
demonstrate the biological role of RDCP1 in conferring stress tolerance. 相似文献
124.
Byun HO Jung HJ Seo YH Lee YK Hwang SC Hwang ES Yoon G 《Experimental cell research》2012,318(15):1808-1819
Transforming growth factor β1 (TGF β1) induces Mv1Lu cell senescence by persistently producing mitochondrial reactive oxygen species (ROS) through decreased complex IV activity. Here, we investigated the molecular mechanism underlying the effect of TGF β1 on mitochondrial complex IV activity. TGF β1 progressively phosphorylated the negative regulatory sites of both glycogen synthase kinase 3 (GSK3) α and β, corresponding well to the intracellular ROS generation profile. Pre-treatment of N-acetyl cysteine, an antioxidant, did not alter this GSK3 phosphorylation (inactivation), whereas pharmacological inhibition of GSK3 by SB415286 significantly increased mitochondrial ROS, implying that GSK3 phosphorylation is an upstream event of the ROS generation. GSK3 inhibition by SB415286 decreased complex IV activity and cellular O(2) consumption rate and eventually induced senescence of Mv1Lu cell. Similar results were obtained with siRNA-mediated knockdown of GSK3. Moreover, we found that GSK3 not only exists in cytosol but also in mitochondria of Mv1Lu cell and the mitochondrial GSK3 binds complex IV subunit 6b which has no electron carrier and is topologically located in the mitochondrial intermembrane space. Involvement of subunit 6b in controlling complex IV activity and overall respiration rate was proved with siRNA-mediated knockdown of subunit 6b. Finally, TGF β1 treatment decreased the binding of the subunit 6b to GSK3 and subunit 6b phosphorylation. Taken together, our results suggest that GSK3 inactivation is importantly involved in TGF β1-induced complex IV defects through decreasing phosphorylation of the subunit 6b, thereby contributing to senescence-associated mitochondrial ROS generation. 相似文献
125.
126.
Two bioactive phloroglucinol derivatives, dioxinodehydroeckol (DHE) and phlorofucofuroeckol A (PFF-A) were isolated from edible marine brown alga, Ecklonia stolonifera, and evaluated for effects on cell surface FcεRI expression in KU812F cells. DHE and PFF-A were found to reduce the cell surface expression, and total cellular protein and mRNA levels for the FcεRI α chain. Moreover, both compounds exerted inhibitory effects against the elevation of intracellular calcium concentration [Ca2+]i and histamine release from anti-FcεRI α chain antibody (CRA-1)-stimulated cells. These inhibitory effects were stronger for PFF-A than for DHE. These results show that two phloroglucinol derivatives, DHE and PFF-A, may exert anti-allergic effects via the inhibition of FcεRI expression, calcium influx, and degranulation in basophils, and contributes to the pharmacological activities of marine brown alga, including E. stolonifera. 相似文献
127.
Distillers dried grains with solubles (DDGS) and corn gluten feed (CGF) are major coproducts of ethanol production from corn dry grind and wet milling facilities, respectively. These coproducts contain important nutrients, nevertheless, high levels of phosphorus (P). About 50-80% of the P in these products is in an organically bound form known as phytate. The phytate P in these products cannot be digested by nonruminant animals. Consequently, large quantities of phytate are deposited into the soil with the animal wastes which potentially could cause P pollution in soil and underground water resources. As regulations on the concentration of P material in ethanol production coproducts become more restrictive, measures need to be taken for effective extraction of phytate P from the coproducts to make these processes more environmentally compatible. Proper marketing of coproducts is critical to the overall economy of ethanol production facilities. In this study, distribution of P compounds in different streams of dry grind and wet milling operations was determined. In the dry grind process, the highest P concentration was found to be in the condensed distillers solubles (CDS) at about 1.34 wt.% (db). About 59% of P in this stream was in phosphates form. The highest concentration of P in the wet milling process was found in the light steep water at about 3.4 wt.% (db). In this stream, about 22% of P was attributed to phosphates. 相似文献
128.
Seon-Soo Kim Hyun-Jung Byun Sang-Hoon Kim Han-Hyoung Lee Suk Jun Lee Sang Joon Kim Chung-Gyu Park Taehoon Chun 《Biotechnology letters》2010,32(2):203-208
Lymphocyte activation gene-3 (LAG-3; CD223) is a transmembrane protein that is structurally similar to CD4. Since LAG-3 has
a much higher binding affinity to MHC class II than that of CD4, several approaches using soluble LAG-3 were used to modulate
immune responses by activation or inhibition of MHC class II expressing antigen presenting cells. In this study, we constructed
soluble pig LAG-3 containing a critical binding site (D1 and D2 region) to MHC class II molecules, combined with a constant
region of an immunoglobulin (Ig) heavy chain. Flow cytometry analyses indicated that soluble pig LAG-3 binds to both pig and
human MHC class II molecules. Moreover, soluble pig LAG-3 can inhibit human lymphocyte proliferation in the human–pig xenogeneic
mixed lymphocyte reaction in a dose-dependent manner. These results indicate that soluble pig LAG-3 may be useful for controlling
the xenogeneic T cell immune responses between the human and pig. 相似文献
129.
Haofan Wang Youngjoo Byun Cyril Barinka Mrudula Pullambhatla Hyo-eun C. Bhang James J. Fox Jacek Lubkowski Ronnie C. Mease Martin G. Pomper 《Bioorganic & medicinal chemistry letters》2010,20(1):392-397
We report a strategy based on bioisosterism to improve the physicochemical properties of existing hydrophilic, urea-based GCPII inhibitors. Comprehensive structure–activity relationship studies of the P1′ site of ZJ-43- and DCIBzL-based compounds identified several glutamate-free inhibitors with Ki values below 20 nM. Among them, compound 32d (Ki = 11 nM) exhibited selective uptake in GCPII-expressing tumors by SPECT-CT imaging in mice. A novel conformational change of amino acids in the S1′ pharmacophore pocket was observed in the X-ray crystal structure of GCPII complexed with 32d. 相似文献
130.
Distillers’ grains and corn fiber are the coproducts of the dry grind and wet corn milling industries, respectively. Availability of distillers’ grains and corn fiber at the ethanol plant and their high levels of lignocellulosic material make them attractive feedstock for conversion to ethanol. In this study, dilute sulfuric acid hydrolysis for the conversion of distillers’ grains and corn fiber to monomeric sugars and the formation of furfural were investigated. The extent of solubilization of biomass beyond monomeric sugars was also monitored. Biomass loadings in the range of 5–20 wt.% at 5% intervals, acid concentrations in the range of 0.5–1.5 vol.% at 0.5% intervals, and temperatures of 120 and 140 °C were studied. The highest yields of monomeric sugars were observed when the least amount of biomass loading was pretreated with the highest concentration of sulfuric acid and when the temperature was 140 °C. For the majority of the cases under consideration, the most effective period of hydrolysis appeared to be during the initial 20–30 min of the reaction. Formation of furfural during the course of hydrolysis was significantly lower at 120 °C and also lower for the distillers’ grains samples compared with the corn fiber samples. The total amount of the solubilized matter during the hydrolysis was significantly higher than the amount of the monomeric sugars. Analyses according to standard procedure were performed to quantify moisture, oil, carbohydrates, and ash in distillers’ grains and corn fiber samples. The total carbohydrate content of distillers’ grains and corn fiber were 57.7 ± 2.0 and 77.0 ± 1.0 wt.%, respectively. The presented results will provide a foundation for the suitability of the pretreated distillers’ grains and corn fiber for enzymatic hydrolysis step. 相似文献