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991.
Han‐Guang Wu Xiao‐Jie Ju Rui Xie Ying‐Mei Liu Jin‐Gen Deng Catherine Hui Niu Liang‐Yin Chu 《先进技术聚合物》2011,22(9):1389-1394
A novel ion‐imprinted strategy is developed for synthesizing responsive hydrogels with rapid response to potassium ions. With potassium ions as templates, ion‐imprinted poly(N‐isopropylacrylamide‐co‐benzo‐15‐crown‐5‐acrylamide) (P(NIPAM‐co‐B15C5Am)) hydrogels are synthesized with 15‐crown‐5 crown ethers mounted on the polymer networks in pairs; therefore, it is very easy and fast for the crown ethers to capture potassium ions again by their Venus flytrap action and form stable 2:1 “host–guest” complexes with potassium ions in the ion‐recognition process. As a result, the response rate of the ion‐imprinted hydrogels to potassium ions is significantly faster than that of normal P(NIPAM‐co‐B15C5Am) hydrogels in which 15‐crown‐5 crown ethers are randomly pendent on the polymeric networks. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
992.
The title compound N-(2,6-difluorobenzoyl)-N'-[5-(4-trifluoromethylphenyl)-1,3,4-thiadiazol-2-yl]urea(C17H9F5N4O2S, Mr = 428.34) has been synthesized by the reaction of 2-amino-5-(4-trifluoromethylphenyl)-l,3,4-thiadiazole with 2,6-difluorobenzoyl isocyanate, and its
crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/n with a = 10.7316(13), b = 10.5617(13), c = 16.037(2) (A), β =106.408(2)°, V= 1743.6(4) (A)3, Z = 4, Dc = 1.632 g/cm3, μ = 0.260 mm-1, F(000) = 864, the final R = 0.0599 and wR = 0.1420 for 3467 observed reflections with I > 2o(Ⅰ). The urea group, which adopts a planar configuration mediated by the intramolecular N-H…O hydrogen bond, is nearly coplanar with the thiadiazole and 4-trifluoromethylbenzene rings. The title compound was found to exhibit good fungicidal activity against Rhizoctonia solani and Botrytis cinerea. 相似文献
993.
Butyl modified poly(allylamine)s with butyl substitution degrees of 15%to 70%were prepared.The polymers show pH sensitive property and lower critical solution temperature(LCST)behavior.The LCST appears at lower temperature,lower pH and lower polymer concentration for the polymer with higher butylated degree.The binding of native lysozyme with the polymers depends on the hydrophobicity of the polymers at the pH range that the protein and the polymer carry the same positive charges.The increase of polymer hydrophobicity can increase the binding with lysozyme,but the self-aggregation of the polymer decreases the binding.The bound lysozyme molecules can recover their native activity completely after the dissociation of the complexes.Compared with native lysozyme,the denatured one which exposes the hydrophobic residues can increase the binding with the polymer and form stable complex nanoparticles. 相似文献
994.
Synthetic hydrogels can be used as scaffolds that not only favor endothelial cells(ECs) proliferation but also manipulate the behaviors and functions of the ECs.In this review paper,the effect of chemical structure,Young’s modulus (E) and zeta potential(ξ) of synthetic hydrogel scaffolds on static cell behaviors,including cell morphology,proliferation, cytoskeleton structure and focal adhesion,and on dynamic cell behaviors,including migration velocity and morphology oscillation,as well as on EC function such as anti-platelet adhesion,are reported.It was found that negatively charged hydrogels,poly(2-acrylamido-2-methylpropanesulfonic sodium)(PNaAMPS) and poly(sodium p-styrene sulphonate) (PNaSS),can directly promote cell proliferation,with no need of surface modification by any cell-adhesive proteins or peptides at the environment of serum-containing medium.In addition,the Young’s modulus(E) and zeta potential(ξ) of hydrogel scaffolds are quantitatively tuned by copolymer hydrogels,poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm), in which the two kinds of negatively charged monomers NaAMPS and NaSS are copolymerized with neutral monomer,N,N-dimethylacrylamide(DMAAm).It was found that the critical zeta potential of hydrogels manipulating EC morphology,proliferation,and motility isξcritical= -20.83 mV andξcritical= -14.0 mV for poly(NaAMPS-co-DMAAm) and poly(NaSS-co-DMAAm),respectively.The above mentioned EC behaviors well correlate with the adsorption of fibronectin, a kind of cell-adhesive protein,on the hydrogel surfaces.Furthermore,adhered platelets on the EC monolayers cultured on the hydrogel scaffolds obviously decreases with an increase of the Young’s modulus(E) of the hydrogels,especially when E>60 kPa.Glycocalyx assay and gene expression of ECs demonstrate that the anti-platelet adhesion well correlates with the EC-specific glycocalyx.The above investigation suggests that understanding the relationship between physic-chemical properties of synthetic hydrogels and cell responses is essential to design optimal soft and wet scaffolds for tissue engineering. 相似文献
995.
A series of poly(γ-benzyl l-glutamate) (PBLG)/polyurethane (PU) containing carboxyl group blend membranes was prepared by casting the polymer blend solution
in dimethylformamide (DMF). The surface morphology of the PBLG/PU blend membranes was investigated by atomic force microscopy
(AFM) and scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PBLG/PU blend membranes were
studied by differential scanning calorimetry (DSC), tensile tests and other physical methods. It was revealed that the introduction
of PU could exert outstanding effects on the morphology and the properties of PBLG membrane. 相似文献
996.
Cai-Feng Wang He-Yi Xie Yu-Peng Cheng Li Chen Michael Z. Hu Su Chen 《Colloid and polymer science》2011,289(4):395-400
This paper describes the first synthesis of cadmium sulfide (CdS)-poly(lactic acid) (PLA) nanocomposites and their transparent
fluorescent films by covalently grafting PLA onto the surfaces of CdS nanocrystals (NCs). Synthesis of the nanocomposites
involved two steps. Lactic acid (LA)-capped CdS NCs were first prepared by reacting cadmium chloride (CdCl2) with sodium sulfide (Na2S) using LA as the organic ligand in H2O/N,N-dimethylformamide (DMF) solution. CdS–PLA nanocomposites were then formed by in situ ring-opening polymerization of lactide
on the surface of modified CdS NCs. We also demonstrated herein the fabrication of the transparent fluorescent films of CdS–PLA
nanocomposites by blending as-prepared nanocomposites with high-molecular-weight PLA. The as-prepared CdS NCs and their nanocomposites
were studied by transmission electron microscopic imaging, thermogravimetric analyses, and spectroscopic measurements (ultraviolet–visible
absorption and photoluminescence). The results revealed that the CdS–polymer nanocomposites exhibited good optical properties
in terms of their photoluminescence and transparency. 相似文献
997.
998.
999.
用重铬酸钾氧化法获得了表面羧基化的碳纳米管(MWCNT-COOH), 进一步通过酰胺化反应合成了2-氨基吡啶修饰的碳纳米管(MWCNT-AP). 利用傅里叶变换红外(FT-IR)光谱、核磁共振氢谱(1H NMR)、X射线光电子能谱(XPS)等对合成的碳纳米管进行了表征. 透射电镜(TEM)结果表明MWCNT-COOH在乙醇等极性溶剂中易于簇集, 而MWCNT-AP 溶液具有良好的分散性和稳定性. 辣根过氧化酶(HRP)可通过物理作用吸附于MWCNT-AP 和MWCNT-COOH表面, 负载量分别为187.5 和153.0 μg·mg-1. HRP被吸附后, 其Soret 带明显红移, 说明HRP 与MWCNT-AP 或MWCNT-COOH 的结合位点位于血红素辅基的附近. 圆二色谱结果表明MWCNT-AP 对HRP的二级结构也有一定影响. 酶动力学实验结果表明MWCNT-AP 能有效地吸附HRP及其底物3,3',5,5'-四甲基联苯胺(TMB), 并使HRP的酶催化反应最大速率(Vmax)显著提高. 相似文献
1000.
基于Aguado等人拟合的APW势能面(PES), 运用准经典轨线(QCT)方法, 对反应Li+HF(ν=0, j=0)→LiF+H的动力学性质进行了计算. 主要研究了不同碰撞能条件下的反应截面、转动取向、产物散射角分布和竞争反应模式等. 结果表明, 该反应存在直接提取型和间接插入型两种反应模式, 在低能量下反应以间接插入反应模式为主, 能量大于200 meV时则以直接提取反应为主. 相似文献