全文获取类型
收费全文 | 789篇 |
免费 | 42篇 |
出版年
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 21篇 |
2014年 | 30篇 |
2013年 | 50篇 |
2012年 | 47篇 |
2011年 | 35篇 |
2010年 | 32篇 |
2009年 | 34篇 |
2008年 | 46篇 |
2007年 | 51篇 |
2006年 | 53篇 |
2005年 | 52篇 |
2004年 | 52篇 |
2003年 | 44篇 |
2002年 | 44篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 13篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有831条查询结果,搜索用时 15 毫秒
81.
Koichi Ohkuma Kouki Matsuda Ryusho Kariya Hiroki Goto Shintaro Kamei Takayoshi Hamamoto Seiji Okada 《Microbiology and immunology》2015,59(7):381-388
Activated protein C (APC) has an anticoagulant action and plays an important role in blood coagulation homeostasis. In addition to its anticoagulant action, APC is known to have cytoprotective effects, such as anti‐apoptotic action and endothelial barrier protection, on vascular endothelial cells and monocytes. However, the effects of APC on DCs have not been clarified. To investigate the effects of APC on human DCs, monocytes were isolated from peripheral blood and DC differentiation induced with LPS. APC significantly inhibited the production of inflammatory cytokines TNF‐α and IL‐6 during differentiation of immature DCs to mature DCs, but did not inhibit the production of IL‐12 and anti‐inflammatory cytokine IL‐10. Interestingly, treatment with 5 μg/mL, but not 25 μg/mL, of APC significantly enhanced production of IL‐10. In addition, protein C, which is the zymogen of APC, did not affect production of these cytokines. On the other hand, flow cytometric analysis of DC's surface molecules indicated that APC does not significantly affect expression of CD83, a marker of mDC differentiation, and the co‐stimulatory molecules CD40, CD80 and CD86. These results suggest that APC has anti‐inflammatory effects on human DCs and may be effective against some inflammatory diseases in which the pathogenesis involves TNF‐α and/or IL‐6 production. 相似文献
82.
83.
Enthalpies of mixing of R- and S-limonene in non-polar solvents in the entire range of mole fractions were measured at 298.15 K. The enthalpies of mixing were negative for all concentrations in dilute concentration, but increased by increasing the concentration of limonenes in solutions. Ultimately positive excess enthalpies were shown in high concentration. Enthalpies of mixing were compared with theoretical estimation by COSMO-RS. 相似文献
84.
85.
Suzuki H Ikeda N Kobayashi K Terashima Y Shimada Y Suzuki T Hagiwara T Hatakeyama S Nagaoka K Yoshida J Saito Y Tanaka J Hayashi M 《Mutation research》2005,583(2):133-145
We conducted simultaneous liver and peripheral blood micronucleus assays in young rats with seven rodent hepatocarcinogens-4,4'-methylenedianiline (MDA), quinoline, o-toluidine, 4-chloro-o-phenylenediamine (CPDA), dimethylnitrosamine (DMN), p-dimethylaminoazobenzene (DAB), and di(2-ethylhexyl)phthalate (DEHP)-and two mutagenic chemicals-kojic acid and methylmethanesulfonate (MMS). Quinoline, DMN, and DAB were positive in the liver assay, while o-toluidine, kojic acid, DAB, and MMS were positive in the peripheral blood assay. o-Toluidine, kojic acid, and DAB are reportedly negative in mouse bone marrow micronucleus assays, indicating a species difference. Our results revealed a correlation between micronucleus induction in hepatocytes and hepatocarcinogenicity. This technique can be useful for the detection of micronucleus-inducing chemicals that require metabolic activation, and it enables simultaneous comparison of the micronucleus-inducing potential of chemicals in the liver and peripheral blood in the same individual. 相似文献
86.
87.
Iron regulatory protein 2 (IRP2), a regulator of iron metabolism, is modulated by ubiquitination and degradation. We have shown that IRP2 degradation is triggered by heme-mediated oxidation. We report here that not only Cys201, an invariant residue in the heme regulatory motif (HRM), but also His204 is critical for IRP2 degradation. Spectroscopic studies revealed that Cys201 binds ferric heme, whereas His204 is a ferrous heme binding site, indicating the involvement of these residues in sensing the redox state of the heme iron and in generating the oxidative modification. Moreover, the HRM in IRP2 has been suggested to play a critical role in its recognition by the HOIL-1 ubiquitin ligase. Although HRMs are known to sense heme concentration by simply binding to heme, the HRM in IRP2 specifically contributes to its oxidative modification, its recognition by the ligase, and its sensing of iron concentration after iron is integrated into heme. 相似文献
88.
Suzuki T Matsuura A Kouketsu A Nakagawa H Miyata N 《Bioorganic & medicinal chemistry letters》2005,15(2):331-335
In order to find novel non-hydroxamate histone deacetylase (HDAC) inhibitors, we synthesized several suberoylanilide hydroxamic acid (SAHA)-based compounds designed on the basis of the catalytic mechanism of HDACs. Among these compounds, 5b was found to be as potent as SAHA. Kinetic enzyme assays and molecular modeling suggested that the mercaptoacetamide moiety of 5b interacts with the zinc in the active site of HDACs and removes a water molecule from the reactive site of the deacetylation. 相似文献
89.
Carbon cycling and budget in a forested basin of southwestern Hokkaido,northern Japan 总被引:5,自引:1,他引:4
Hideaki?ShibataEmail author Tsutom?Hiura Yumiko?Tanaka Kentaro?Takagi Takayoshi?Koike 《Ecological Research》2005,20(3):325-331
Quantification of annual carbon sequestration is very important in order to assess the function of forest ecosystems in combatting global climate change and the ecosystem responses to those changes. Annual cycling and budget of carbon in a forested basin was investigated to quantify the carbon sequestration of a cool-temperate deciduous forest ecosystem in the Horonai stream basin, Tomakomai Experimental Forest, northern Japan. Net ecosystem exchange, soil respiration, biomass increment, litterfall, soil-solution chemistry, and stream export were observed in the basin from 1999–2001 as a part of IGBP-TEMA project. We found that 258 g C m–2 year–1 was sequestered annually as net ecosystem exchange (NEE) in the forested basin. Discharge of carbon to the stream was 4 g C m–2 year–1 (about 2% of NEE) and consisted mainly of dissolved inorganic carbon (DIC). About 43% of net ecosystem productivity (NEP) was retained in the vegetation, while about 57% of NEP was sequestered in soil, suggesting that the movement of sequestered carbon from aboveground to belowground vegetation was an important process for net carbon accumulation in soil. The derived organic carbon from aboveground vegetation that moved to the soil mainly accumulated in the solid phase of the soil, with the result that the export of dissolved organic carbon to the stream was smaller than that of dissolved inorganic carbon. Our results indicated that the aboveground and belowground interaction of carbon fluxes was an important process for determining the rate and retention time of the carbon sequestration in a cool-temperate deciduous forest ecosystem in the southwestern part of Hokkaido, northern Japan. 相似文献
90.
Shu Qin Liu Takayoshi Kuroda-Sowa Yusaku Suenaga Megumu Munakata 《Inorganica chimica acta》2005,358(4):919-926
Coordination polymers of [2.2]paracyclophane (pcp) with in situ silver(I) perfluoro-dicarboxylates characterized by single crystal X-ray analysis are described. Structures are found to strongly depend on the dicarboxylate spacer (n). With disilver(I) tetrafluorosuccinate ((CF2)n(COOAg)2, n = 2), 3D network with composition of [Ag4(pcp)(C2F4(CO2)2)2] (1) forms in which silver salts afford infinite double chains and pcp act as linkages between chains. Changing the silver salt to disilver hexafluoroglutarate ((CF2)n(COOAg)2, n = 3) produces 3D pillared-layer structure of composition of [Ag4(pcp)(C3F6(CO2)2)2] · THF (2) (THF = tetrahydrofuran), in which silver salts form 2D sheets and pcp act as pillars between the sheets. With silver octafluoroadipate (HO2C(CF2)nCO2Ag, n = 4), 2-fold interpenetrated diamond structure, [Ag2(pcp)2(HO2CC4F8CO2)2]2 · 2toluene (3), is obtained in which silver-anion chains and silver-pcp chains are connected with each other in the perpendicular manner. The three complexes represent unprecedented metal-organic networks of silver(I) multicarboxylates and polycyclic aromatic compounds. Additionally, the effects of the dicarboxylate conformations as well as the solvents on the resulting structures were discussed. 相似文献