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101.
Surface modification by poly(ethylene glycol) (PEGylation) has been acknowledged as a powerful strategy in minimizing non-specific reactions for biomedical devices. Once applied into manufacture of drug/gene delivery systems, PEGylation has demonstrated to significantly improve their biocompatibility and stealthiness in physiological environment. Nonetheless, reluctant cell membrane affinities thus cellular uptake efficiencies owing to PEGylation brought up further issues that are imperative to be resolved. Pertain to this PEGylation dilemma, we attempted to introduce peptide (GPLGVRG) linkage between block copolymer of PEG-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} PAsp(DET), wherein the cationic PAsp(DET) could self-assemble with pDNA into nanoscaled complex core. Noteworthy was the peptide linkage whose amino acids sequence could be specifically recognized and degraded by matrix metalloproteinases (MMPs) (overexpressed in extracellular milieu of tumors). Therefore, our subsequent studies validated facile detachment of PEGylation from the aforementioned polyplex micelles upon treatment of MMPs, which elicited improved cytomembrane affinities and cellular uptake efficiencies. In addition, promoted escape from endosome entrapment was also confirmed through direct endosome membrane destabilization by PAsp(DET), which was further elucidated to be attributable to dePEGylation as well as elevated charged density of PAsp(DET) in acidic endosomes. These benefits from dePEGylation eventually contributed to promoted gene expression at the affected cells and potent tumor growth suppression based on anti-angiogenic approach. Therefore, our developed strategy has provided a facile approach in overcoming the dilemma of PEGylation, which could be informative in design of drug/gene delivery systems. 相似文献
102.
This paper introduces the Independent Components Analysis (ICA) to voltammetry and extends possibility of the qualitative and quantitative analysis of binary mixtures of similar oxidation/reduction potentials. It was demonstrated that even in the case of distance between peaks potentials equal to 10 mV, determinations may be realized according to typical validation criteria. The methodology was presented using the simulated data and capabilities and limitations of the method were described. Further, the usefulness of ICA was presented for voltammograms registered during simultaneous determination of copper and antimony, and thallium and indium. The results of high practical importance for chemical analysis were achieved and documented. In the quantitative analysis a property was extensively used, that ICA is an unsupervised method. 相似文献
103.
血清中甲胎蛋白(AFP)的准确测量对于癌症的临床诊断和治疗具有重要意义.电感耦合等离子体质谱法(ICP-MS)具有灵敏度高、检出限低、多元素同时检测等优点,但用于血清中低丰度蛋白的检测时,检出限常不及荧光检测法,因此,提高ICP-MS免疫分析测量低丰度蛋白质时的灵敏度具有重要意义.本研究发现,增强液能很大程度增加Eu信号强度,选取醋酸、醇类、EDTA三类有机试剂模拟增强液来探索增强机理.结果表明:酸性体系能增加目标元素在基体中的稳定性,减少其在管壁的吸附;碳原子或分子容易接受电子提高Eu的电离效率;EDTA能与金属离子结合,减少吸附,但同时EDTA与其它金属结合引入更多的干扰,从而使空白信号增大,5% HAc既能满足酸性要求也能满足含碳量要求,作为基体时铕的灵敏度最高,同时也不影响空白信号.因此选择5% HAc作为解离液,并应用于人血清中甲胎蛋白含量的测定,线性范围为1~600 μg/L,检出限为0.57 μg/L,采用基体改进ICP-MS测量人血清中AFP的含量与TRFIA测量结果一致,且精密度要优于TRFIA的测量结果. 相似文献
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105.
This paper offers some new evidence on the polymorphism of solid state of liquid crystalline aromatic copolyesters which were prepared in our laboratory. The effects of different treatment conditions(quenching and annealing) on solid structure have been examined mainly by DSC and X-ray diffraction. The discussion focuses on the supercooled mesophase and low temperature solid-solid transition, the shifting of double melting peaks of annealed samples and the changing of their ΔH data depending on the treatment temperature, time and thermal scanning rate. 相似文献
106.
On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS 总被引:1,自引:0,他引:1
Within the last decade, the first generation of flow injection (FI) has been supplemented by sequential injection (SI), also termed the second generation, and, recently, by the third generation, i.e., SI-Lab-on-Valve (SI-LOV). As apparent from the literature, FI and/or SI have become dominant as substitutes for labor-intensive, manual, sample-pre-treatment and/or solution-handling procedures prior to analyte detection by inductively coupled plasma mass spectrometry (ICP-MS). The present review presents and discusses the progress of the state of the art in implementing miniaturized FI/SI systems for on-line matrix separation and pre-concentration of trace levels of metals with detection by ICP-MS. It highlights some of the frequently applied on-line, sample-pre-treatment schemes, including solid phase extraction (SPE), on-wall molecular sorption and precipitate/(co)-precipitate retention using a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn is interfaced to ICP-MS, as conducted in the present authors' group. It discusses the future outlook in this field. 相似文献
107.
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109.
制备了可用作氨基酸及小分子聚合物的MALDI-FTMS分析基质的β-环糊精包覆多壁碳纳米管.通过引入β-环糊精改善其碳纳米管亲水性.所制备的β-环糊精包覆多壁碳纳米管的扫描电镜图表明,该碳纳米管呈现纳米带状结构.与通常的氧化碳纳米管相比,所制备的β-环糊精改性CNT具有更低的背景信号.进一步采用氨基酸及聚乙二醇等小分子化合物对所制备的碳纳米管进行评价,得到很强的氨基酸及聚乙二醇的碱金属离子加合峰,表明该材料可使小分子化合物解吸离子化,且背景干扰小不会影响到小分子化合物检测.由此可见,制备的β-环糊精包覆多壁碳纳米管适于小分子化合物的MALDI-MS分析. 相似文献
110.