全文获取类型
收费全文 | 329篇 |
免费 | 58篇 |
国内免费 | 14篇 |
专业分类
化学 | 159篇 |
晶体学 | 3篇 |
力学 | 20篇 |
综合类 | 11篇 |
数学 | 163篇 |
物理学 | 45篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 32篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 15篇 |
2012年 | 22篇 |
2011年 | 20篇 |
2010年 | 20篇 |
2009年 | 14篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 27篇 |
2005年 | 19篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有401条查询结果,搜索用时 15 毫秒
11.
Kuihua ZhangChen Huang Chunyang WangXiumei Mo Salem S. Al-DeyabMohamed El-Newehy 《Polymer Degradation and Stability》2011,96(12):2266-2275
Nanofibrous scaffolds of silk fibroin (SF) and poly(l-lactic acid-co-?-caprolactone) (P(LLA-CL)) blends fabricated via electrospinning possessed good mechanical property and biocompatibility, as demonstrated by a previous study in vitro. However, the degradation behavior of the scaffolds, which may significantly influence tissue repair and regeneration, needs further exploration. In this study, in vitro degradation of pure SF, P(LLA-CL) and SF/P(LLA-CL) blended nanofibrous scaffolds were performed in phosphate-buffered saline (PBS, pH 7.4 ± 0.1) at 37 °C for 6 months. A series of analyses and characterizations (including morphologic changes, loss weight, pH changes of PBS solutions, DSC, XRD and FTIR-ATR) were conducted to the nanofibrous scaffolds after degradation and the results showed that the pure SF nanofibrous scaffolds were not completely degradable in PBS while pure P(LLA-CL) nanofibrous scaffolds had the fastest degradation rate. Moreover, the addition of SF reduced the degradation rate of P(LLA-CL) in SF/P(LLA-CL) blended nanofibrous scaffolds. This was probably caused by the intermolecular interactions between SF and P(LLA-CL), which hindered the movement of P(LLA-CL) molecular chains. 相似文献
12.
通过近年来有关中医药膳防治复发性阿弗他溃疡的研究,从中西医角度论述了复发性阿弗他溃疡的发病机理,挖掘出有效防治复发性阿弗他溃疡的中医药膳,总结了中医药膳的功能成分如何作用于复发性阿弗他溃疡,归纳了可行的中医药膳调理的方法和应用原则,为开展药膳干预复发性阿弗他溃疡发病提供理论基础. 相似文献
13.
Organ Repair,Hemostasis, and In Vivo Bonding of Medical Devices by Aqueous Solutions of Nanoparticles 下载免费PDF全文
Prof. Dr. Anne Meddahi‐Pellé Aurélie Legrand Dr. Alba Marcellan Liliane Louedec Prof. Dr. Didier Letourneur Prof. Dr. Ludwik Leibler 《Angewandte Chemie (International ed. in English)》2014,53(25):6369-6373
Sutures are traumatic to soft connective tissues, such as liver or lungs. Polymer tissue adhesives require complex in vivo control of polymerization or cross‐linking reactions and currently suffer from being toxic, weak, or inefficient within the wet conditions of the body. Herein, we demonstrate using Stöber silica or iron oxide nanoparticles that nanobridging, that is, adhesion by aqueous nanoparticle solutions, can be used in vivo in rats to achieve rapid and strong closure and healing of deep wounds in skin and liver. Nanoparticles were also used to fix polymer membranes to tissues even in the presence of blood flow, such as occurring after liver resection, yielding permanent hemostasis within a minute. Furthermore, medical devices and tissue engineering constructs were fixed to organs such as a beating heart. The simplicity, rapidity, and robustness of nanobridging bode well for clinical applications, surgery, and regenerative medicine. 相似文献
14.
Improving Site‐Directed RNA Editing In Vitro and in Cell Culture by Chemical Modification of the GuideRNA 下载免费PDF全文
Paul Vogel Marius F. Schneider Jacqueline Wettengel Dr. Thorsten Stafforst 《Angewandte Chemie (International ed. in English)》2014,53(24):6267-6271
Adenosine‐to‐inosine deamination can be re‐addressed to user‐defined mRNAs by applying phosphothioate/2′‐methoxy‐modified guideRNAs. Dense chemical modification of the guideRNA clearly improves performance of the covalent conjugates inside the living cell. Furthermore, careful positioning of a few modifications controls editing selectivity in vitro and was exploited for the challenging repair of the Factor 5 Leiden missense mutation. 相似文献
15.
Poly(lactide-co-glycolide)-poly(ethylene glycol)-poly(lactide-co-glycolide)(PLGA-PEG-PLGA) triblock copolymer was synthesized through the ring-opening polymerization of LA and GA with PEG as macroinitiator and stannous octoate as catalyst. The amphiphilic copolymer self-assembled into micelles in aqueous solutions, and formed hydrogels as the increase of temperature at relatively high concentrations(〉 15 wt%). The favorable degradability of the hydrogel was confirmed by in vitro and in vivo degradation experiments. The good cellular and tissular compatibilities of the thermogel were demonstrated. The excellent adhesion and proliferation of bone marrow mesenchymal stem cells endowed PLGA-PEGPLGA thermogelling hydrogel with fascinating prospect for cartilage tissue engineering. 相似文献
16.
17.
18.
This study develops deteriorating items production inventory models with random machine breakdown and stochastic repair time. The model assumes the machine repair time is independent of the machine breakdown rate. The classical optimization technique is used to derive an optimal solution. A numerical example and sensitivity analysis are shown to illustrate the models. The stochastic repair models with uniformly distributed repair time tends to have a larger optimal total cost than the fixed repair time model, however the production up time is less than the fixed repair time model. Production and demand rate are the most sensitive parameters for the optimal production up time, and demand rate is the most sensitive parameter to the optimal total cost for the stochastic model with exponential distribution repair time. 相似文献
19.
The level of repair analysis (LORA) gives answers to three questions that are posed when deciding on how to maintain capital goods: (1) which components to repair upon failure and which to discard, (2) at which locations in the repair network to perform each type of repairs, and (3) at which locations in the network to deploy resources, such as test equipment. The goal is to achieve the lowest possible life cycle costs. Various models exist for the LORA problem. However, they tend to be restrictive in that specific business situations cannot be incorporated, such as having repair equipment with finite capacity or the occurrence of unsuccessful repairs or no-fault-founds. We discuss and model such practically relevant extensions to an existing minimum cost flow formulation for the LORA problem. In an extensive numerical experiment, we show that incorporating the model refinements leads to a substantial change in the costs in general. The repair strategy changes substantially only when incorporating finite resource capacities or a probability of unsuccessful repair that is decreasing with an increasing echelon level. 相似文献
20.
Back Cover: Quantum Mechanics/Molecular Mechanics Study on the Oxygen Binding and Substrate Hydroxylation Step in AlkB Repair Enzymes (Chem. Eur. J. 2/2014) 下载免费PDF全文