全文获取类型
收费全文 | 379篇 |
免费 | 49篇 |
国内免费 | 7篇 |
专业分类
综合类 | 4篇 |
化学工业 | 176篇 |
金属工艺 | 4篇 |
机械仪表 | 6篇 |
轻工业 | 98篇 |
水利工程 | 1篇 |
无线电 | 26篇 |
一般工业技术 | 119篇 |
自动化技术 | 1篇 |
出版年
2024年 | 2篇 |
2023年 | 17篇 |
2022年 | 25篇 |
2021年 | 37篇 |
2020年 | 29篇 |
2019年 | 32篇 |
2018年 | 20篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 24篇 |
2014年 | 26篇 |
2013年 | 45篇 |
2012年 | 10篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有435条查询结果,搜索用时 15 毫秒
21.
Peng-Kai Wu Zhi Tao Zhao Ouyang Jiang-Ye Cao Di Geng Jin Liu 《Drug development and industrial pharmacy》2016,42(9):1424-1433
Liposomes have successfully been used for decades to encapsulate and protect drugs that are prone to deactivation in the body. The present study aimed to demonstrate the use of liposomes to encapsulate cordycepin, an adenosine analog that quickly loses its activity in vivo. The cordycepin-loaded liposomes were prepared by the ammonium sulfate gradient approach, and its in vitro and in vivo antitumour activities were evaluated using BEL-7402 cells and hepatocellular carcinoma H22 transplanted tumors, respectively. An MTT assay was used to observe the cytotoxicity of cells treated with cordycepin and cordycepin-loaded liposomes in vitro. High-content screening (HSC) was carried out using Hoechst 33342 to detect apoptotic cells and the ratio of cells in different cell cycle stages. The data demonstrated that both the cordycepin and the cordycepin-loaded liposomes resulted in clear cytotoxicity with IC50 values of 18.97 and 29.39?μg/mL, respectively. The latter showed significantly strong inhibitory effects on H22 tumor growth in mice, while the former did not show any inhibitory effects on tumor growth. In addition, the HSC assay showed that the cordycepin-loaded liposomes resulted in a higher rate of apoptosis than the cordycepin alone in BEL-7402 cells. Further data analysis revealed that the cells treated with cordycepin-loaded liposomes were predominately arrested at the G2/M phase (p?0.05), while those treated with cordycepin alone were arrested in the G0/G1 phase (p?0.05). In conclusion, these results suggest that liposomes can enhance and maintain the in vivo anti-tumor activity of cordycepin. 相似文献
22.
Yan Ge 《Journal of Experimental Nanoscience》2016,11(5):345-358
Tea tree oil (TTO) exhibits excellent broad-spectrum antimicrobial activity. In order to preserve it from the degradation in the presence of oxygen, light and temperature, TTO was encapsulated in liposomes (LTTOs) using the thin-membrane hydration and sonication method, and characterised by Zetasizer for size and size distribution, transmission electron microscope for morphology, zeta-potential for surface charge, entrapment efficiency and TTO release from the nanoparticles. The antimicrobial activities of phosphate-buffered saline solution containing TTO, unloaded liposomes and LTTOs suspension were determined by twofold serial broth dilution technique. The size of LTTOs was 75 nm and the encapsulation efficiency of 96.08% was obtained. LTTOs exhibited slow release of TTO and superior broad-spectrum antimicrobial effects compared with free TTO. Liposomes not only effectively encapsulated TTO to form a stable liposome suspension, but also enhanced inhibition and bactericidal effect on the TTO-tolerant strain. The liposomal systems carrying TTO may be a potential alternative for effective antimicrobial agents. 相似文献
23.
Objective: The objective of this study was to prepare bufadienolides-loaded liposome (BU-lipo). Methods: The BU-lipo was prepared by a thin-film hydration method involving sonication and lyophilization procedures. The lyophilized BU-lipo was characterized with regard to the appearance and particle size by scanning electron microscopy, transmission electron microscopy, and photon correlation spectroscopy. The entrapment efficiency (EE) of BU-lipo was evaluated by the microdialysis technique. Results: In the optimal formulation, Lipoid E-80® and the mass ratio of cholesterol to lipid were fixed at 1.25% and 0.05. The media diameters of BU-lipo before and after lyophilization were about 100 nm, and the EEs of bufalin (B), cinobufagin (C), and resibufogenin (R) were 86.5%, 90.0%, and 92.1%, respectively. In the EE study, the probe recoveries of B, C, and R were 21.53?±?1.14%, 19.49?±?1.34%, and 20.19?±?1.25%, respectively, at a flow rate of 4 μL/min by the gain method. The EE of BU-lipo evaluated by microdialysis and ultrafiltration were equivalent. Conclusion: The lyophilized BU-lipo contained trehalose (10%) was stable up to 6 months in a desiccator under 2ºC–8ºC. The microdialysis technique has a wide application perspective in the investigation of the free-drug concentration of microcarrier systems. 相似文献
24.
25.
Rapid Light‐Triggered Drug Release in Liposomes Containing Small Amounts of Unsaturated and Porphyrin–Phospholipids
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dandan Luo Nasi Li Kevin A. Carter Cuiyan Lin Jumin Geng Shuai Shao Wei‐Chiao Huang Yueling Qin G. Ekin Atilla‐Gokcumen Jonathan F. Lovell 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(22):3039-3047
Prompt membrane permeabilization is a requisite for liposomes designed for local stimuli‐induced intravascular release of therapeutic payloads. Incorporation of a small amount (i.e., 5 molar percent) of an unsaturated phospholipid, such as dioleoylphosphatidylcholine (DOPC), accelerates near infrared (NIR) light‐triggered doxorubicin release in porphyrin–phospholipid (PoP) liposomes by an order of magnitude. In physiological conditions in vitro, the loaded drug can be released in a minute under NIR irradiation, while liposomes maintain serum stability otherwise. This enables rapid laser‐induced drug release using remarkably low amounts of PoP (i.e., 0.3 molar percent). Light‐triggered drug release occurs concomitantly with DOPC and cholesterol oxidation, as detected by mass spectrometry. In the presence of an oxygen scavenger or an antioxidant, light‐triggered drug release is inhibited, suggesting that the mechanism is related to singlet oxygen mediated oxidization of unsaturated lipids. Despite the irreversible modification of lipid composition, DOPC‐containing PoP liposome permeabilization is transient. Human pancreatic xenograft growth in mice is significantly delayed with a single chemophototherapy treatment following intravenous administration of 6 mg kg?1 doxorubicin, loaded in liposomes containing small amounts of DOPC and PoP. 相似文献
26.
Erica Bazzan Mariaenrica Tin Alvise Casara Davide Biondini Umberto Semenzato Elisabetta Cocconcelli Elisabetta Balestro Marco Damin Claudia Maria Radu Graziella Turato Simonetta Baraldo Paolo Simioni Paolo Spagnolo Marina Saetta Manuel G. Cosio 《International journal of molecular sciences》2021,22(12)
Extracellular vesicles (EVs) are a family of particles/vesicles present in blood and body fluids, composed of phospholipid bilayers that carry a variety of molecules that can mediate cell communication, modulating crucial cell processes such as homeostasis, induction/dampening of inflammation, and promotion of repair. Their existence, initially suspected in 1946 and confirmed in 1967, spurred a sharp increase in the number of scientific publications. Paradoxically, the increasing interest for EV content and function progressively reduced the relevance for a precise nomenclature in classifying EVs, therefore leading to a confusing scientific production. The aim of this review was to analyze the evolution of the progress in the knowledge and definition of EVs over the years, with an overview of the methodologies used for the identification of the vesicles, their cell of origin, and the detection of their cargo. The MISEV 2018 guidelines for the proper recognition nomenclature and ways to study EVs are summarized. The review finishes with a “more questions than answers” chapter, in which some of the problems we still face to fully understand the EV function and potential as a diagnostic and therapeutic tool are analyzed. 相似文献
27.
Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Atsuko Uyeda Dr. Takayoshi Watanabe Dr. Yasuhiko Kato Prof. Hajime Watanabe Prof. Tetsuya Yomo Prof. Takahiro Hohsaka Dr. Tomoaki Matsuura 《Chembiochem : a European journal of chemical biology》2015,16(12):1797-1802
Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation. 相似文献
28.
Barbara Geusens Mireille Van Gele Sien Braat Stefaan C. De Smedt Marc C. A. Stuart Tarl W. Prow Washington Sanchez Michael S. Roberts Niek N. Sanders Jo Lambert 《Advanced functional materials》2010,20(23):4077-4090
The extent to which nanoscale‐engineered systems cross intact human skin and can exert pharmacological effects in viable epidermis is controversial. This research seeks to develop a new lipid‐based nanosome that enables the effective delivery of siRNA into human skin. The major finding is that an ultraflexible siRNA‐containing nanosome—prepared using DOTAP, cholesterol, sodium cholate, and 30% ethanol—penetrates into the epidermis of freshly excised intact human skin and is able to enter into the keratinocytes. The nanosomes, called surfactant‐ethanol‐cholesterol‐osomes (SECosomes), show excellent size, surface charge, morphology, deformability, transfection efficiency, stability, and skin penetration capacity after complexation with siRNA. Importantly, these nanosomes have ideal characteristics for siRNA encapsulation, in that the siRNA is stable for at least 4 weeks, they enable highly efficient transfection of in vitro cultured cells, and are shown to transport siRNA delivery through intact human skin where changes in the keratinocyte cell state are demonstrated. It is concluded that increasing flexibility in nanosomes greatly enhances their ability to cross the intact human epidermal membrane and to unload their payload into targeted epidermal cells. 相似文献
29.
Zhiming Liu Ying Zheng Bowen Yue Yali Luo Zhaoxin Cao Jingyi Su Xinyu Wang Yan Zhang Yifei Zhang Bingxue Wang Xiaoliang Cheng Zhiyong Zhou Xuemei Ge 《European Journal of Lipid Science and Technology》2023,125(9):2300009
Jujube peel pigment (JP), an ideal natural water-soluble pigment extracted from jujube peel, mainly consists of flavonoids and possesses a wide range of physiological activities. In this study, JP-loaded multivesicular liposomes (JP-MVL) were prepared using the double emulsification method. JP-MVL was characterized, and its encapsulation efficiency was determined using the UV-Vis method. Furthermore, the release behavior and antioxidant capacity of JP-MVL were evaluated in vitro. The results displayed in the structure of JP-MVL were spherical with internal vesicles; the average particle size of JP-MVL was 5.63 μm, and the zeta potential was −69.50 mV. Analysis of the release results indicated that the best-fitting models in PBS (Phosphate buffered saline pH 7.4) and 0.9% NaCl were the Higuchi and first-order kinetic models, respectively. The cytotoxicity of JP-MVL at the appropriate concentrations was negligible and had a good protective effect against UVB-induced photodamage. 相似文献
30.