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961.
邻对苯二酚的合成方法 总被引:4,自引:1,他引:4
用自制的钛硅沸石TS-1为催化剂,对H2O2存在下苯酚直接羟基化合成邻、对苯二酚的反应条件,主要影响因素及机理进行了探讨,发现该民传统的合成方法相比,反应的选择性及转化率较高,工艺简单,成本低和污染少。 相似文献
962.
963.
Magnetic Cu2+-chelated silica particles using polyacrylamide as a metal-chelating ligand was developed and used for the immobilization of laccase by coordination.The effect of pH and temperature on the enzymatic property of immobilized laccase and its catalytic capacity for pentachlorophenol(PCP) degradation were evaluated systemically.Compared with free laccase,the immobilized laccase showed improved acid adaptabihty and thermal stability.The immobilized laccase prepared in this work exhibited a good catalytic capacity for PCP removal from aqueous solutions. 相似文献
964.
采用反复冻融细胞破裂法、硫酸铵分级盐析以及羟基磷灰石柱层析,从钝顶螺旋藻中提取出高纯度的藻蓝蛋白样品,纯度(A62a/A280)达4.1.该蛋白的紫外-可见吸收光谱表明其特征吸收峰为280、360、620nm,荧光光谱表明其最大发射波长为650 nm.以该藻蓝蛋白为荧光探针,发展了一种基于荧光猝灭法的Hg2检测新方法.并考察了缓冲体系、缓冲液pH值、反应时间、温度以及藻蓝蛋白的浓度等因素对汞离子检测的影响,在0.05 mol/L、pH7.5的磷酸二氢钾-磷酸氢二钠缓冲液中,当藻蓝蛋白浓度为3 mg/L、反应时间为30 min、反应温度为30℃时,该方法的线性范围为0.1~10μmol/L,检出限为0.056 μmol/L.该方法表现出良好的汞离子传感选择性,而且当干扰离子与汞离子的浓度比为40∶1时,多种共存离子对汞离子的检测影响较小.该方法荧光探针提取容易,价格低且环境友好,具有较高的灵敏度和较好的重现性. 相似文献
965.
Dong LiuPeng Yuan Daoyong Tan Hongmei Liu Tong WangMingde Fan Jianxi ZhuHongping He 《Journal of colloid and interface science》2012,388(1):176-184
Hierarchically porous carbons were prepared using a facile preparation method in which diatomite was utilized as both template and catalyst. The porous structures of the carbon products and their formation mechanisms were investigated. The macroporosity and microporosity of the diatomite-templated carbons were derived from replication of diatom shell and structure-reconfiguration of the carbon film, respectively. The macroporosity of carbons was strongly dependent on the original morphology of the diatomite template. The macroporous structure composed of carbon plates connected by the pillar- and tube-like macropores resulted from the replication of the central and edge pores of the diatom shells with disk-shaped morphology, respectively. And another macroporous carbon tubes were also replicated from canoe-shaped diatom shells. The acidity of diatomite dramatically affected the porosity of the carbons, more acid sites of diatomite template resulted in higher surface area and pore volume of the carbon products. The diatomite-templated carbons exhibited higher adsorption capacity for methylene blue than the commercial activated carbon (CAC), although the specific surface area was much smaller than that of CAC, due to the hierarchical porosity of diatomite-templated carbons. And the carbons were readily reclaimed and regenerated. 相似文献
966.
Chu X Ci X He J Jiang L Wei M Cao Q Guan M Xie X Deng X He J 《Molecules (Basel, Switzerland)》2012,17(3):3586-3598
Rosmarinic acid (RA), a polyphenolic phytochemical, is a natural prolyl oligopeptidase inhibitor. In the present study, we found that RA exerted potent anti-inflammatory effects in in vivo models of acute lung injury (ALI) induced by lipopolysaccharide (LPS). Mice were pretreated with RA one hour before challenge with a dose of 0.5 mg/kg LPS. Twenty-four hours after LPS was given, bronchoalveolar lavage fluid (BALF) was obtained to measure pro-inflammatory mediator and total cell counts. RA significantly decreased the production of LPS-induced TNF-a, IL-6, and IL-1β compare with the LPS group. When pretreated with RA (5, 10, or 20 mg/kg) the lung wet-to-dry weight (W/D) ratio of the lung tissue and the number of total cells, neutrophils and macrophages in the BALF were decreased significantly. Furthermore, RA may enhance oxidase dimutase (SOD) activity during the inflammatory response to LPS-induced ALI. And we further demonstrated that RA exerts anti-inflammation effect in vivo models of ALI through suppresses ERK/MAPK signaling in a dose dependent manner. These studies have important implications for RA administration as a potential treatment for ALI. 相似文献
967.
Parameters such as solution concentrations and composition of the ambient atmosphere are known to be important in phase and morphology control in the solvothermal synthesis of CdS semiconductor nanorods (NRs), but a clear understanding of the underlying mechanisms involved is lacking. In this work, a series of experiments were performed to demonstrate that the key factor affecting the phase and morphology of CdS NRs is the amount of O(2) in the space above the reaction solution in the sealed vessel relative to the amount of precursors in solution: O(2)-depleted conditions resulted in more cubic phase CdS and thick polycrystalline NRs with an aspect ratio usually less than 3, which have small blue shifts in band-edge emission and little surface trap emission, while O(2)-rich conditions resulted in more hexagonal-phase CdS and slim single-crystal NRs, which have significantly blue shifted band-edge emission and relatively strong surface trap emission. Thus, increasing the amount of solution in the vessel, changing the ambient atmosphere from air to N(2), and increasing the reagent concentration all lower the molar ratio of O(2) to reagents and lead to more cubic phase and thicker NRs. The results indicate that the composition of the "empty" section of the reaction vessel plays as important a role as the composition of the liquid in determining the phase and morphology, something that has been overlooked in earlier work. A mechanism to explain the effect of oxygen on the nucleation and growth stages has been proposed on the basis of those results and further supported by shaking experiments and ZnS NR synthesis manipulation. The CdS NRs synthesized under different conditions showed obvious differences in photocatalytic activity, which indicated that controlling the synthetic process can lead to materials with tailored photocatalytic activity. 相似文献
968.
SDS is mostly used to enhance the solubilization and extraction of membrane proteins due to its strong detergency and low cost. Nevertheless, SDS interferes with the subsequent procedures and needs to be removed from the samples. In this work, a special gradient gel electrophoresis (GGE) system was developed to remove SDS from the SDS-solubilized protein samples. As a proof-of-principle experiment, the GGE system was designed to be composed of an agarose loading layer, six polyacrylamide fractionation layers with different concentrations and a high-concentration polyacrylamide sealing layer. The advantages of the GGE system are that it not only can electrophoretically remove SDS efficiently so that the protein loss resulted from the repeated gel washing after electrophoresis was avoided, but also can reduce the complexity of the sample, prevent the precipitation of proteins after loading and avoid the loss of proteins with low molecular weight during the electrophoresis. Using GGE system, about 85% of SDS in the sample and gel was electrophoretically removed and the proteins were fractionated. Compared with the two representative gel-based sample cleanup methods reported in literature, GGE-based strategy significantly improved the identification efficiency of proteins in terms of the number and coverage of the identified proteins. 相似文献
969.
Zhao JS Wang JH He WB Ruan YB Jiang YB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3631-3636
The induced aggregation of achiral building blocks by a chiral species to form chiral aggregates with memorized chirality has been observed for a number of systems. However, chiral memory in isolated aggregates of achiral building blocks remains rare. One possible reason for this discrepancy could be that not much is understood in terms of designing these chiral aggregates. Herein, we report a strategy for creating such isolable chiral aggregates from achiral building blocks that retain chiral memory after the facile physical removal of the chiral templates. This strategy was used for the isolation of chiral homoaggregates of neutral achiral π-conjugated carboxylic acids in pure aqueous solution. Under what we have termed an "interaction-substitution" mechanism, we generated chiral homoaggregates of a variety of π-conjugated carboxylic acids by using carboxymethyl cellulose (CMC) as a mediator in acidic aqueous solutions. These aggregates were subsequently isolated from the CMC templates whilst retaining their memorized supramolecular chirality. Circular dichroism (CD) spectra of the aggregates formed in the acidic CMC solution exhibited bisignated exciton-coupled signals of various signs and intensities that were maintained in the isolated pure homoaggregates of the achiral π-conjugated carboxylic acids. The memory of the supramolecular chirality in the isolated aggregates was ascribed to the substitution of COOH/COOH hydrogen-bonding interaction between the carboxylic acid groups within the aggregates for the hydrogen-bonding interactions between the COOH groups of the building blocks and the chiral templates. We expect that this "interaction-substitution" procedure will open up a new route to isolable pure chiral aggregates from achiral species. 相似文献
970.
We constructed the copper(I)-binding domain of Mycobacterium tuberculosis (Mtb) CDC 1551 (residues 1-162) between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP), and formed a novel genetically encoded fluorescent copper(I) responsive protein (PMtb). The sensitivity and selectivity to copper(I) of the PMtb was sought. The experiments showed that the copper(I)-binding domain of the PMtb was highly sensitive and selective towards copper(I). 相似文献