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871.
配基表面密度可控为定量研究生物分子相互作用提供了精准的分子基础。然而,经典混合自组装的方法控制配基密度对于不同自组装体系不具有普适性。本文报道了一种基于表面乙烯砜基反应动力学的配基表面密度调控方法。以Nα,Nα-二(羧甲基)-L-赖氨酸(ab-NTA)为生物配基模型,对该表面反应进行了催化剂筛选并利用X射线光电子能谱(XPS)和表面膜电位对该表面反应进行了表征。采用静态水接触角的方法对表面反应的动力学进行了定量表征,计算得到反应速率常数为0.0012 min-1。采用表面等离子体共振(SPR)分析了该生物功能表面结合组氨酸标签蛋白(SA-6His)的能力,结果表明该表面比传统NHS-NTA表面具有更高的蛋白结合量和结合强度。通过控制反应时间和催化剂种类制备了四种配基密度不同的生物功能表面,并利用SPR对四种表面进行了蛋白质静态吸附实验。实验结果表明通过控制反应时间和催化剂类型均能够实现配基表面密度的调控,并且可以实现表面多价态的调控。 相似文献
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873.
Futian Liu Jianfu Ding Mei Li Michael Day Gilles Robertson Ming Zhou 《Macromolecular rapid communications》2002,23(14):844-848
Highly fluorinated poly(ether sulfone)s were prepared by a modified polycondensation technique, using a molecular sieve dehydrating apparatus in order to efficiently remove water under mild conditions. Consequently, side reactions were minimized, which resulted in the formation of polymers free of microgels. This reaction was also used to introduce pentafluorostyrene moieties into the polymer to provide crosslinking functionalities. 相似文献
874.
用合成的3-三氟甲基苯侧基聚醚砜(3F-PES)作为波导芯层材料制作了新型硅基聚合物阵列波导光栅(AWG)复用器.采用DSC,TGA和AFM等方法对3F-PES的光学性质和热稳定性进行了表征.DSC和TGA结果显示,3F-PES的玻璃化转变温度为170℃,在空气中5%的热失重温度为542℃,表明具有非常好的热稳定性.3F-PES溶液在旋涂时具有很好的成膜性,AFM照片显示,粗糙度起伏为0.35nm.近红外吸收谱表明,3F-PES在光通讯波段有较小的吸收,适合用来制作低损耗的光波导器件.用3F-PES作为波导芯层材料制作的八通道硅基聚合物阵列波导光栅(AWG)复用器的通道间隔为1.603nm,中心波长为1550.15nm. 相似文献
875.
González-Hernández I Ruiz-Olmedo MI Cárdenas G Jung-Cook H 《Biomedical chromatography : BMC》2012,26(2):267-272
The development and validation of an LC-MS/MS method for the simultaneous determination of albendazole metabolites (albendazole sulfoxide and albendazole sulfone) in human plasma are described. Samples of 200 μL were extracted with ether-dichloromethane-chloroform (60:30:10, v/v/v). The chromatographic separation was performed using a C(18) column with methanol-formic acid 20 mmol/L (70:30) as the mobile phase. The method was linear in a range of 20-5000 ng/mL for albendazole sulfoxide and 10-1500 ng/mL for albendazole sulfone. For both analytes the method was precise (RSD < 12%) and accurate (RE <7%) with high recovery (>90%). The method was successfully applied to determine the plasma and cerebrospinal fluid levels of albendazole sulfoxide and albendazole sulfone in patients with subarachnoidal neurocysticercosis who received albendazole at 30 mg/kg per day for 7 days. This LC-MS/MS method yielded a quick, simple and reliable protocol for determining albendazole sulfoxide and albendazole sulfone concentrations in plasma and cerebrospinal fluid samples and is applicable to therapeutic monitoring. 相似文献
876.
In many reactions involving selenosulfonate or thiosulfonate,the sutfone group often leaves in form of benzenesutfinic acid or sodium benzenesulfinate.A one-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions to afford selenocarbamates and allyl sulfone compounds is reported.The sulfinic acid as the first-step side product is converted to the allyl sulfone compound by water promoted reaction with allyl alcohol.Water acts as both an oxygen source of selenocarbamates and as a promoter to drive the second step reactio n.The reactions have the advantages of mild conditions,green,environment-friendly,and high atomic economy. 相似文献
877.
用密度泛函方法(DFT)研究了PdCl2催化炔酸烯丙酯环化反应的机理. 在B3LYP/6-311G**水平上优化了各反应中间体和过渡态的结构. 计算结果表明, 反应是放热的, 主要经历了炔键的卤钯化、烯烃对烯基钯的迁移插入以及β-杂原子消除等过程. 烯烃的迁移插入是反应的手性决定步骤, β-杂原子消除是反应的速率控制步骤. 理论预测的主要产物是与实验吻合的(Z,R)-α-亚烷基-γ-丁内酯. 相似文献
878.
879.
880.
Jong-Chan Lee Morton H. Litt Charles E. Rogers 《Journal of Polymer Science.Polymer Physics》1998,36(1):75-83
Gas barrier properties of alkylsulfonylmethyl-substituted poly(oxyalkylene)s are discussed. Oxygen permeability coefficients of three methylsulfonylmethyl-substituted poly(oxyalkylene)s, poly[oxy(methylsulfonylmethyl)ethylene] (MSE), poly[oxy(methylsulfonylmethyl)ethylene-co-oxyethylene] (MSEE), and poly[oxy-2,2-bis (methylsulfonylmethyl)trimethylene oxide] (MST) were measured. MSEE, which has the most flexible backbone of the three polymers, had an oxygen permeability coefficient at 30°C of 0.0036 × 10−13 cm3(STP)·cm/cm2·s·Pa higher than that of MSE, 0.0014 × 10−13 cm3(STP)·cm/cm2·s·Pa, because the former polymer's Tg was near room temperature. MST with two polar groups per repeat unit and the highest Tg showed the highest oxygen permeability, 0.013 × 10−13 cm3(STP) · cm/cm2·s·Pa, among the three polymers, probably because steric hindrance between the side chains made the chain packing inefficient. As the side chain length of poly[oxy(alkylsulfonylmethyl)ethylene] increased, Tg and density decreased and the oxygen permeability coefficients increased. The oxygen permeability coefficient of MSE at high humidity (84% relative humidity) was seven times higher than when it was dry because absorbed water lowered its Tg. At 100% relative humidity MSE equilibrated to a Tg of 15°C after 2 weeks. A 50/50 blend of MSE/MST had oxygen barrier properties better than the individual polymers (O2 permeability coefficient is 0.0007 × 10−13 cm3(STP)·cm/cm2 ·s·Pa), lower than most commercial high barrier polymers. At 100% relative humidity, it equilibrated to a Tg of 42°C, well above room temperature. These are polymer systems with high gas barrier properties under both dry and wet conditions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 75–83, 1998 相似文献