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The dissolved oxygen (DO) content of the ocean provides potential evidence and clues for the waxing and waning of marine productivity, ocean circulation, global climate change, and the evolution of ecological communities. On the basis of the analysis of the Benthic Foraminiferal Oxygen Index (BFOI), the percentage of epifaunal benthic foraminifers, and the redox-sensitive trace elements (Mo/Al) in Core MD12-3432, we reconstruct the evolution of deep water DO content in the northern South China Sea (SCS) during the past 400 ka and discuss the mechanisms of variable DO content. The results show that the changes of BFOI, Mo/Al, and the percentage of epifaunal benthic foraminifer present a similar pattern, which may reflect the variations of the DO content in seawater since 400 ka. Both variations in BFOI and Mo/Al indicate that the DO content was high during most time of marine isotope stage (MIS) 11 to mid-MIS 6, then decreased in late-MIS 6, and remained stable in MIS 5. It increased in MIS 4 and decreased until MIS 2, and then rose again. The non-synchronous variations between bottom water DO and benthic foraminiferal δ18O indicate that the DO content is not controlled by glacial-interglacial cyclic environmental variations. Comparing the biomarker productivity index with the DO content of water, we find that the DO content is affected mainly by productivity. Bulimina, Uvigerina and Chilostomella oolina are high productivity species. The accumulation rates of Bulimina and Uvigerina are higher during 61–15 kyr interval, but the accumulation rate of C. oolina is higher during 168–130 kyr. The results infer that different intensity of primary productivity and DO during these two periods. The DO and phytoplankton total (PT) show the opposite relation, which also indicates that the DO is affected by primary productivity, and the combined action of productivity and DO decides the growth of Bulimina, Uvigerina, and C. oolina. Besides the influences of productivity, the change of DO in the ocean is also affected by oceanic circulation. 相似文献
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2-Hydroxyoctadecanoic acid was resolved into D and L isomers as salts of 1-phenylethylamine enantiomers The diastereomers of phenylethylamides of 2-hydroxy fatty acids and the corresponding derivatives with protected hydroxy group (acetyl, methyl, trifluoro-acetyl, trimethylsilyl) are well separated by thin-layer or gas-liquid chromatography. This allows a simple microanalysis of configuration and optical purity of 2-hydroxy fatty acids. With this method 2-hydroxy fatty acids from sphingomyelin of the honey-bee were shown to belong exclusively to the D series. 相似文献
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High spatial resolution mass spectrometry imaging reveals the genetically programmed,developmental modification of the distribution of thylakoid membrane lipids among individual cells of maize leaf 下载免费PDF全文
Maria Emilia Dueñas Adam T. Klein Liza E. Alexander Marna D. Yandeau‐Nelson Basil J. Nikolau Young Jin Lee 《The Plant journal : for cell and molecular biology》2017,89(4):825-838
Metabolism in plants is compartmentalized among different tissues, cells and subcellular organelles. Mass spectrometry imaging (MSI) with matrix‐assisted laser desorption ionization (MALDI) has recently advanced to allow for the visualization of metabolites at single‐cell resolution. Here we applied 5‐ and 10 μm high spatial resolution MALDI‐MSI to the asymmetric Kranz anatomy of Zea mays (maize) leaves to study the differential localization of two major anionic lipids in thylakoid membranes, sulfoquinovosyldiacylglycerols (SQDG) and phosphatidylglycerols (PG). The quantification and localization of SQDG and PG molecular species, among mesophyll (M) and bundle sheath (BS) cells, are compared across the leaf developmental gradient from four maize genotypes (the inbreds B73 and Mo17, and the reciprocal hybrids B73 × Mo17 and Mo17 × B73). SQDG species are uniformly distributed in both photosynthetic cell types, regardless of leaf development or genotype; however, PG shows photosynthetic cell‐specific differential localization depending on the genotype and the fatty acyl chain constituent. Overall, 16:1‐containing PGs primarily contribute to the thylakoid membranes of M cells, whereas BS chloroplasts are mostly composed of 16:0‐containing PGs. Furthermore, PG 32:0 shows genotype‐specific differences in cellular distribution, with preferential localization in BS cells for B73, but more uniform distribution between BS and M cells in Mo17. Maternal inheritance is exhibited within the hybrids, such that the localization of PG 32:0 in B73 × Mo17 is similar to the distribution in the B73 parental inbred, whereas that of Mo17 × B73 resembles the Mo17 parent. This study demonstrates the power of MALDI‐MSI to reveal unprecedented insights on metabolic outcomes in multicellular organisms at single‐cell resolution. 相似文献
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Thaís C. Lima Rodrigo Lucarini Angelica C. Volpe Carolina Q.J. de Andrade Alice M.P. Souza Patricia M. Pauletti Ana H. Januário Guilherme V. Símaro Jairo K. Bastos Wilson R. Cunha Alexandre Borges Rosangela da Silva Laurentiz Valéria A. Conforti Renato L.T. Parreira Carly H.G. Borges Giovanni F. Caramori Karla F. Andriani Márcio L.A. e Silva 《Bioorganic & medicinal chemistry letters》2017,27(2):176-179
(?)-Cubebin (CUB), isolated from seeds of Piper cubeba, was used as starting material to obtain the derivatives (?)-hinokinin (HK) and (?)-O-benzyl cubebin (OBZ). Using paw edema as the experimental model and different chemical mediators (prostaglandin and dextran), it was observed that both derivatives were active in comparison with both negative (5% Tween® 80 in saline) and positive (indomethacin) controls. The highest reduction in the prostaglandin-induced edema was achieved by OBZ (66.0%), while HK caused a 59.2% reduction. Nonetheless, the dextran-induced paw edema was not significantly reduced by either of the derivatives (HK or OBZ), which inhibited edema formation by 18.3% and 3.5%, respectively, in contrast with the positive control, cyproheptadine, which reduced the edema by 56.0%. The docking analysis showed that OBZ presented the most stable ligand-receptor (COX-2 – cyclooxygenase-2) interaction in comparison with CUB and HK. 相似文献
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Kulrawee Sidthipong Jun Ma Wei Lin Yu Yan Feng Wang Susumu Kobayashi Satoshi Kishino Naoki Koide Takashi Yokochi Kuniki Kato Shoshiro Okada Kazuo Umezawa 《Bioorganic & medicinal chemistry letters》2017,27(3):562-566
(?)-Dehydroxymethylepoxyquinomicin ((?)-DHMEQ, 1) is a specific inhibitor of NF-κB. It binds to SH group in the specific cysteine residue of NF-κB components with its epoxide moiety to inhibit DNA binding. In the present research, we have designed and synthesized an epoxide-free analog called (S)-β-salicyloylamino-α-exo-methylene-?-butyrolactone (SEMBL, 3). SEMBL inhibited DNA binding of NF-κB component p65 in vitro. It inhibited LPS-induced NF-κB activation, iNOS expression, and inflammatory cytokine secretions. It also inhibited NF-κB and cellular invasion in ovarian carcinoma ES-2 cells. Moreover, its stability in aqueous solution was greatly enhanced compared with (?)-DHMEQ. Thus, SEMBL has a potential to be a candidate for a new anti-inflammatory and anticancer agent. 相似文献
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Reaction of the oxo-molybdenum(V) precursor [MoTp*(O)Cl2] [Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate] with H2NC6H4R-4 (R = OEt; OPr) in refluxing toluene in the presence of Et3N afforded the binuclear oxo-bridged oxo(arylimido) molybdenum(V) complexes [Tp*Mo(O)Cl](μ-O)[Tp*Mo(NC6H4OR-4)Cl]. Surprisingly, a similar reaction between [MoTp*(O)Cl2] and C6H5NH2 yielded the previously reported compound [{MoTp*(O)Cl}2(μ-O)] as the only product. The new compounds were characterized by microanalytical data, mass spectrometry, IR and 1H NMR spectroscopy. Cyclic voltammetric studies of the new compounds, of the previously reported compounds [Tp*Mo(O)Cl](μ-O)[Tp*Mo(NAr)Cl] (Ar = C6H4OMe-4, C6H4F-3, C6H4Cl-4, C6H4Br-4, and C6H4I-3), and of [{MoTp*(O)Cl}2(μ-O)] revealed a reversible one-electron oxidation process that is little affected by the nature of the substituent on the aryl group, whereas it is greatly affected by replacement of the imido ligand with an oxo ligand. The [{MoTp*(O)Cl}2(μ-O)] compound also shows a one-electron reduction process. 相似文献
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长白山阔叶红松(Pinus koraiensis)林种子雨组成及其季节动态 总被引:6,自引:2,他引:4
为了解阔叶红松(Pinus koraiensis)林的种子雨组成及其在时间和空间上的动态变化,在长白山阔叶红松林25 hm2样地内,设置了150个种子收集器,收集掉落于种子收集器中的果实、种子等.所有收集到的样品分别鉴定其种类并分为成熟种实、未成熟种实、花序和果实或种子碎片及其附属物4类,计算各类别的数量,而后分别烘干秤重.从2005年6月到2006年11月,共收集到隶属11科12属20种的种实及其生殖器官残体.累计收集到121291粒种实,其中成熟种实23147粒,仅占所有种实总个体数的19.1%.种实数最多的树种是紫椴(Tilia amurensis)和水曲柳(Fraxinus mandshurica),两个树种种实的个体数占总个体数的90%.对2006年5月~11月种子雨季节动态的分析发现:种实在7月中旬至10月下旬数量极大,但主要由未成熟种实组成;在10月中旬出现成熟种实散落高峰,但未成熟种实仍占一定的比例.按每个收集器收集到的成熟种实数统计,成熟种实数量在100~200之间的收集器数量最多.按每个收集器收集到的树种数统计,收集器中最多收到的树种数为7,树种数为3和4的收集器个数最多.对6个主要树种成熟种实所在收集器的空间分布进行分析发现,紫椴和水曲柳的成熟种实在整个样地都有分布,春榆(Ulmus japonica)、糠椴(T. mandshurica)、色木槭(Acer mono)和假色槭(A. pseudo-sieboldianum)则只在样地的局部区域收集到成熟种实.成熟种实的空间分布与母树的空间分布大都表现出明显的相关性,表明这些树种的成熟种实并没有扩散到离母树较远的距离. 相似文献