首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   265篇
  免费   47篇
  国内免费   43篇
化学   286篇
力学   3篇
综合类   1篇
数学   7篇
物理学   58篇
  2023年   7篇
  2022年   23篇
  2021年   33篇
  2020年   23篇
  2019年   20篇
  2018年   18篇
  2017年   11篇
  2016年   24篇
  2015年   17篇
  2014年   19篇
  2013年   31篇
  2012年   25篇
  2011年   15篇
  2010年   9篇
  2009年   8篇
  2008年   13篇
  2007年   14篇
  2006年   5篇
  2005年   11篇
  2004年   4篇
  2003年   3篇
  2002年   6篇
  2001年   2篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
排序方式: 共有355条查询结果,搜索用时 15 毫秒
41.
The ever‐growing interest for finding efficient and reliable methods for treatment of diseases has set a precedent for the design and synthesis of new functional hybrid materials, namely porous nanoparticles, for controlled drug delivery. Mesoporous silica nanoparticles (MSNPs) represent one of the most promising nanocarriers for drug delivery as they possess interesting chemical and physical properties, thermal and mechanical stabilities, and are biocompatibile. In particular, their easily functionalizable surface allows a large number of property modifications further improving their efficiency in this field. This Concept article deals with the advances on the novel methods of functionalizing MSNPs, inside or outside the pores, as well as within the walls, to produce efficient and smart drug carriers for therapy.  相似文献   
42.
Microparticles comprising of cinnamoyl gelatin (type A) (CA-GelA), cinnamoyl gelatin (type B) (CA-GelB), cinnamoyl Pluronic F127 (CA-Plu), and cinnamoyl poly(β-cyclodextrin) (CA-P(βCD)) were prepared as a carrier for doxorubicin (DOX). Folic acid (FA) was covalently attached to CA-GelA as a targeting molecule for cancer cells. The covalent attachment of FA was confirmed by 1H-NMR spectroscopy. On the TEM micrographs, the microparticles were almost circular and they were a few hundreds of nanometers in diameter. The release at pH7.4 of DOX from microparticle/DOX suspension was more extensive when the FA content of microparticles was lower and the temperature of release medium was higher. According to the flow cytometric analysis, the lager amount of FA seemed to make the interaction of the microparticle and KB cell more favorable. On confocal laser fluorescence micrograph, the cell treated with microparticle bearing FA showed relatively strong DOX fluorescence, indicating the strong interaction of the microparticle and KB cells.  相似文献   
43.
Enhanced permeation and retention(EPR) targeting effect of rhodamine B labeled PEG-b-P(LA-co-DHP) [PEG:poly(ethylene glycol);LA:L-lactide;DHP:2,2-dihydroxylmethyl-propylene carbonate] micelles(RhB-micelles) was observed in H22 liver cancer bearing mice.The RhB-micelles were prepared by conjugating rhodamine B with the DHP units of amphiphilic block copolymer PEG-b-P(LA-co-DHP) followed by subsequent self-assembling of the conjugate.The parent copolymer PEG-b-P(LA-co-DHP) was synthesized by ring-opening copo...  相似文献   
44.
The implant assisted magnetic targeted drug delivery system of Avilés, Ebner and Ritter is considered both experimentally (in vitro) and theoretically. The results of a 2D mathematical model are compared with 3D experimental results for a magnetizable wire stent. In this experiment a ferromagnetic, coiled wire stent is implanted to aid collection of particles which consist of single domain magnetic nanoparticles (radius ). In order to model the agglomeration of particles known to occur in this system, the magnetic dipole-dipole and hydrodynamic interactions for multiple particles are included. Simulations based on this mathematical model were performed using open source C++ code. Different initial positions are considered and the system performance is assessed in terms of collection efficiency. The results of this model show closer agreement with the measured in vitro experimental results and with the literature. The implications in nanotechnology and nanomedicine are based on the prediction of the particle efficiency, in conjunction with the magnetizable stent, for targeted drug delivery.  相似文献   
45.
Signal transmission through synapses connecting two neurons is mediated by release of neurotransmitter from the presynaptic axon terminals and activation of its receptor at the postsynaptic neurons. γ-Aminobutyric acid (GABA), non-protein amino acid formed by decarboxylation of glutamic acid, is a principal neurotransmitter at inhibitory synapses of vertebrate and invertebrate nervous system. On one hand glutamic acid serves as a principal excitatory neurotransmitter. This article reviews GABA researches on; (1) synaptic inhibition by membrane hyperpolarization, (2) exclusive localization in inhibitory neurons, (3) release from inhibitory neurons, (4) excitatory action at developmental stage, (5) phenotype of GABA-deficient mouse produced by gene-targeting, (6) developmental adjustment of neural network and (7) neurological/psychiatric disorder. In the end, GABA functions in simple nervous system and plants, and non-amino acid neurotransmitters were supplemented.  相似文献   
46.
47.
The concept of using magnetic particles (seeds) as the implant for implant assisted-magnetic drug targeting (IA-MDT) was analyzed in vitro. Since this MDT system is being explored for use in capillaries, a highly porous (ε∼70%), highly tortuous, cylindrical, polyethylene polymer was prepared to mimic capillary tissue, and the seeds (magnetite nanoparticles) were already fixed within. The well-dispersed seeds were used to enhance the capture of 0.87 μm diameter magnetic drug carrier particles (MDCPs) (polydivinylbenzene embedded with 24.8 wt% magnetite) under flow conditions typically found in capillary networks. The effects of the fluid velocity (0.015–0.15 cm/s), magnetic field strength (0.0–250 mT), porous polymer magnetite content (0–7 wt%) and MDCP concentration (C=5 and 50 mg/L) on the capture efficiency (CE) of the MDCPs were studied. In all cases, when the magnetic field was applied, compared to when it was not, large increases in CE resulted; the CE increased even further when the magnetite seeds were present. The CE increased with increases in the magnetic field strength, porous polymer magnetite content and MDCP concentration. It decreased only with increases in the fluid velocity. Large magnetic field strengths were not necessary to induce MDCP capture by the seeds. A few hundred mT was sufficient. Overall, this first in vitro study of the magnetic seeding concept for IA-MDT was very encouraging, because it proved that magnetic particle seeds could serve as an effective implant for MDT systems, especially under conditions found in capillaries.  相似文献   
48.
Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype. In the last years, navitoclax has emerged as a possible treatment for TNBC. Nevertheless, rapid navitoclax resistance onset has been observed thorough Mcl-1 overexpression. As a strategy to overcome Mcl-1-mediated resistance, herein we present a controlled drug co-delivery system based on mesoporous silica nanoparticles (MSNs) targeted to TNBC cells. The nanocarrier is loaded with navitoclax and the Mcl-1 inhibitor S63845 and capped with a MUC1-targeting aptamer ( apMUC1-MSNs(Nav/S63845) ). The apMUC1-capped nanoparticles effectively target TNBC cell lines and successfully induce apoptosis, overcoming navitoclax resistance. Moreover, navitoclax encapsulation protects platelets against apoptosis. These results point apMUC1-gated MSNs as suitable BH3 mimetics nanocarriers in the targeted treatment of MUC1-expressing TNBC.  相似文献   
49.
Highly precise control of molecular structure for developing efficient anticancer drug delivery is challenging. Our method reported herein can satisfy the need for building novel hybrid molecule; this molecule serves as a built‐in transformer that changes its molecular configuration from a pin‐shaped arrangement to a dog bone‐shaped arrangement. This approach led to a significant increase in the efficiency of tumor inhibition. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
50.
Affibody‐conjugated RALA (affi‐RA) are designed for delivering oligomeric 5‐fluorodeoxyuridine (FUdR, metabolite of 5‐FU) strand to raise the selectivity of 5‐fluorouracil (5‐FU), decrease its toxicity and improve its suboptimal therapeutic efficacy. The nanodrugs, FUdR@affi‐RA, are spontaneously assembled by electrostatic interaction between positively charged affi‐RA and negatively charged FUdR15‐strands (15 consecutive FUdR). FUdR@affi‐RA exhibits excellent stability under simulated physiological conditions. Compared with free FUdR, FUdR@affi‐RA shows excellent targeting and higher cytotoxicity in human epidermal growth factor receptor 2 (HER2) overexpressing gastric cancer N87 cells. Moreover, the anticancer mechanism studies reveal that FUdR@affi‐RA enhances the expression and activity of apoptosis‐associated proteins in the Bcl‐2/Bax‐caspase 8,9‐caspase 3 apoptotic pathway induced by FUdR. This study indicates that the fusion vector, affi‐RA, presents a promising delivery system platform for nucleoside analogue drugs and provides a new strategy for the development of therapeutics of cancer treatment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号