全文获取类型
收费全文 | 512篇 |
免费 | 27篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 2篇 |
妇产科学 | 3篇 |
基础医学 | 29篇 |
口腔科学 | 5篇 |
临床医学 | 22篇 |
内科学 | 29篇 |
皮肤病学 | 37篇 |
神经病学 | 1篇 |
特种医学 | 8篇 |
外科学 | 16篇 |
综合类 | 78篇 |
预防医学 | 51篇 |
眼科学 | 6篇 |
药学 | 186篇 |
中国医学 | 82篇 |
肿瘤学 | 6篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 18篇 |
2014年 | 30篇 |
2013年 | 43篇 |
2012年 | 34篇 |
2011年 | 43篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 19篇 |
2007年 | 29篇 |
2006年 | 13篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 15篇 |
2002年 | 10篇 |
2001年 | 8篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有561条查询结果,搜索用时 31 毫秒
1.
Keith P. Reber John D. Sivey Matthew Vollmuth Priyansh D. Gujarati 《Journal of labelled compounds & radiopharmaceuticals》2022,65(9):254-263
Parabens are antimicrobial additives found in a wide array of consumer products. However, the halogenated compounds formed from parabens during wastewater disinfection are a potential environmental concern. In order to identify these transformation products and investigate their mechanism of formation, a synthetic route to ethyl parabens labeled with the stable isotope carbon-13 at specific positions within the benzene ring was developed. This efficient two-step procedure starts from commercially available 13C-labeled phenols and involves (1) initial acylation of the phenol via a Houben–Hoesch reaction with trichloroacetonitrile followed by (2) a modified haloform reaction of the resulting trichloromethyl ketone to afford the corresponding 13C-labeled ethyl parabens in 65%–80% overall yield. The scope of the modified haloform reaction was also investigated, allowing for the synthesis of other parabens derived from primary or secondary alcohols, including 13C- and deuterium-labeled esters. In addition, 4-hydroxybenzoic acid can be formed directly from the common trichloromethyl ketone intermediate upon treatment with lithium hydroxide. This protocol complements existing methods for preparing 13C-labeled paraben derivatives and offers the specific advantages of exhibiting complete regioselectivity in the Houben–Hoesch reaction (to form the para-disubstituted product) and avoiding the need for protecting groups in the modified haloform reaction that forms the paraben esters. 相似文献
2.
The rue (Ruta graveolens) copiousness in rural areas of the Campania Region based a thorough chemical and biological investigation aimed at exploring the seasonal variability of phenol constituents in rue leaves and its influence on their antioxidant, cytotoxic and anti-inflammatory capabilities. To this purpose, hydroalcoholic extracts were prepared from plant samples seasonally collected. LC-ESI-MS/MS techniques were employed to analyze qualitatively and quantitatively the seasonal rue phenol content, whereas different chemical antioxidant assays (by DPPH, ABTS, Fe3+ RP, ORAC, and FCR methods) and XTT redox metabolic activity assay were performed to screen the seasonal phenol complex-related antioxidant and cytotoxic power. The ability of the rue leaf extracts to counteract cyclooxygenase-2 (COX-2) expression was also evaluated. Data obtained highlighted that the adopted extraction procedure markedly pauperized the furanocoumarin content in all the prepared rue extracts. Flavonol glycosides, along with the flavone acacetin and two sinapic acid derivatives were the main constituents of the spring harvest-derived extract, which exerted the highest antioxidant capability in cell-free systems and was capable to inhibit COX-2 synthesis by 44% comparably to dexamethasone, used as positive control. Data provide new insights for developing a proper management of rue plants for new safe industrial purposes in herbal medicine field. 相似文献
3.
Background
Human exposure to crude oil spills is associated with multiple adverse health effects including hematopoietic, hepatic, renal, and pulmonary abnormalities. The purpose of this study was to assess the hematological and liver function indices among the subjects participating in the Gulf oil spill cleanup operations in comparison with the standardized normal range reference values.Methods
Using medical charts, clinical data (including white blood cell [WBC] count, platelet count, hemoglobin, hematocrit, blood urea nitrogen [BUN] creatinine, alkaline phosphatase [ALP], aspartate amino transferase [AST], alanine amino transferase [ALT], and urinary phenol) were gathered for the subjects who were exposed to the Gulf oil spill and analyzed.Results
A total of 117 subjects exposed to the oil spill were included. Over 77% of subjects had WBC counts in the mid range (6-10 × 103 per μL), while none of the subjects had the upper limit of the normal range (11 × 103 per μL). A similar pattern was seen in the platelet counts and BUN levels among the oil spill-exposed subjects. Conversely, over 70% of the subjects had creatinine levels toward the upper limit of the normal range and 23% of subjects had creatinine levels above the upper limit of the normal range (>1.3 mg per dL). Similarly, hemoglobin and hematocrit levels were toward the upper limit of normal in more than two thirds of the subjects. AST and ALT levels above the upper limit of normal range (>40 IU per L) were seen in 15% and 31% of subjects, respectively. Over 80% of subjects had urinary phenol levels higher than detectable levels (2 mg per L).Conclusion
The results of this study support our earlier study findings in which we found that people who participated in oil spill cleanup activities are at risk of developing alterations in hematological profile and liver function. 相似文献4.
比较研究厚朴总酚固体分散体不同制备方法之间的差异。分别使用热熔挤出法、溶剂蒸发法、熔融冷却法制备厚朴总酚Plastone S-630及HPC 2种辅料固体分散体。采用DSC,X-射线衍射评价所制备固体分散体中药物的分散状态;通过FT-IR分析药物与辅料之间可能存在的连接方式;最后通过加速稳定性-溶出试验比较3种工艺的稳定性差异。DSC及X-射线衍射结果显示3种工艺制备的固体分散体中药物均能以无定形态存在;FT-IR结果也无法区别3种工艺间的差异;加速稳定性-溶出试验表明HPC所制备的固体分散体稳定性明显优于Plastone S-630,同种辅料间热熔挤出技术制备的固体分散体稳定性要好于其他2种工艺。 相似文献
5.
Horseradish peroxidase‐catalysed in situ‐forming hydrogels for tissue‐engineering applications 下载免费PDF全文
Jin Woo Bae Jong Hoon Choi Yunki Lee Ki Dong Park 《Journal of tissue engineering and regenerative medicine》2015,9(11):1225-1232
In situ‐forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue‐engineering applications. In recent years, enzyme‐catalysed crosslinking approaches have been emerged as a new approach for developing in situ‐forming hydrogels. In particular, the horseradish peroxidase (HRP)‐catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP‐catalysed crosslinking reaction immediately occurs upon mixing phenol‐rich polymers with HRP and hydrogen peroxide (H2O2) in aqueous media. Based on this unique gel‐forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H2O2. In this review, we outline the versatile properties of HRP‐catalysed in situ‐forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP‐catalysed in situ‐forming hydrogels for tissue regeneration are described. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
目的:建立基于聚类分析和主成分分析的不同产地叶下珠多酚部位高效液相色谱(HPLC)指纹图谱分析方法。方法:采用HPLC法测定9个不同产地叶下珠多酚部位指纹图谱,对其进行相似度分析、聚类分析和主成分分析,高效液相色谱-质谱(HPLC-MS)指认主要成分。结果:叶下珠多酚部位指纹图谱检出7个共有峰,指认了其中5个共有峰,9个不同产地叶下珠多酚部位相似度达到0.972-0.998,聚类分析和主成分分析从化学成分上说明了9批样品的相似性及差异性。结论:以指纹图谱数据为基础,将聚类分析与主成分分析结合起来进行识别,为叶下珠药材的资源利用提供依据。 相似文献
7.
Medhat El‐Mofty Wedad Z. Mostafa Samia Esmat Amira Zayed Heba Mashaly Marwa F. Hussien Sarah I. Ismail 《Dermatologic therapy》2019,32(5)
Depigmentation emerges as a feasible solution for vitiligo universalis and refractory cases of vitiligo vulgaris that hinder patients' quality of life. A range of depigmenting modalities has previously been developed. However, each has its own limitations. Based on skin sensitivity, this study sets out to compare the efficacy and tolerability of “trichloroacetic acid (TCA) peels 25% and 50% and Qs Nd:YAG laser (1,064/532 nm)” for facial depigmentation and “cryotherapy, phenol 88% and Qs Nd:YAG (1,064/532 nm)” for extrafacial skin depigmentation. Forty vitiligo patients were examined and equally divided into facial & extrafacial groups. Regular sessions were performed. Patients' responses were assessed after 3 months or when excellent/complete depigmentation was attained through assessing “depigmentation grade”, “extent of depigmented skin”, “patient satisfaction” and “overall response”. Patients were observed for a six‐month follow‐up period. In facial depigmentation, Qs Nd:YAG showed the highest significant response followed by TCA 50% and 25%. In extrafacial depigmentation cryotherapy, phenol 88% and Qs Nd:YAG laser displayed positive outcomes without significant difference. Among the modalities tested Qs Nd:YAG yielded superior results in facial residual pigmentation in vitiligo when compared to TCA 50% and 25%, whereas in extrafacial sites Qs Nd:YAG, cryotherapy and phenol were equally effective. 相似文献
8.
Supradip Ghosh 《Indian Journal of Critical Care Medicine》2014,18(1):43-45
Intravenous self-injection of phenol resulting in multi-organ failure is reported. The case is discussed, because of the unique nature of exposure to phenol and rapid involvement of multiple organ systems including the central nervous,pulmonary, renal and hematological systems. 相似文献
9.
Tatsuya Kikuchi Katsuyuki Minegishi Hiroki Hashimoto Ming‐Rong Zhang Koichi Kato 《Journal of labelled compounds & radiopharmaceuticals》2013,56(13):672-678
The N‐ or O‐methylation reactions of compounds bearing amide, aniline, or phenol moieties using iodo[11C]methane (1) with the aid of a base are frequently applied to the preparation of 11C‐labeled radiopharmaceuticals. Although sodium hydride and alkaline metal hydroxides are commonly employed as bases in these reactions, their poor solubility properties in organic solvents and hydrolytic activities have sometimes limited their application and made the associated 11C‐methylation reactions difficult. In contrast to these bases, tetrabutylammonium fluoride (TBAF) is moderately basic, highly soluble in organic solvents, and weakly nucleophilic. Although it was envisaged that TBAF could be used as the preferred base for 11C‐methylation reactions using 1, studies concerning the use of TBAF to promote 11C‐methylation reactions are scarce. Herein, we have evaluated the efficiency of the 11C‐methylation reactions of 13 model compounds using TBAF and 1. In most cases, the N‐11C‐methylations were efficiently promoted by TBAF in dimethyl sulfoxide at ambient temperature, whereas the O‐11C‐methylations required heating in some cases. Comparison studies revealed that the efficiencies of the 11C‐methylation reactions with TBAF were comparable or sometimes greater than those conducted with sodium hydride. Based on these results, TBAF should be considered as the preferred base for 11C‐methylation reactions using 1. 相似文献
10.
Mustafa Girgin Burhan Hakan Kanat Refik Ayten Ziya Cetinkaya Zekiye Kanat Ahmet Bozda? Ahmet Turkoglu Yavuz Selim Ilhan 《International surgery》2012,97(4):288-292
Pilonidal disease has been treated surgically and by various other methods for many years. The most important problem associated with such treatment is recurrence, but cosmetic outcome is another important issue that cannot be ignored. Today, crystallized phenol is recognized as a treatment option associated with good medical and cosmetic outcomes. We hypothesized that the addition of laser depilation to crystallized phenol treatment of pilonidal disease might increase the rate of success, and this study aimed to determine if the hypothesis was true. Patients who were treated with crystallized phenol and 755-nm alexandrite laser depilation were retrospectively analyzed. In total, 42 (31 male and 11 female) patients were treated with crystallized phenol and alexandrite laser depilation and were followed up between January 2009 and January 2012. In all, 38 patients (90.5%) had chronic disease and 4 (9.5%) had recurrent disease. Among the patients, 26 (61.9%) recovered following 1 crystallized phenol treatment, and the remaining patients had complete remission following repeated treatment. Some patients needed multiple treatments, even up to 8 times. None of the patients had a recurrence during a mean 24 months (range, 6–30 months) of follow-up. Whatever method of treatment is used for pilonidal disease, hair cleaning positively affects treatment outcome. The present results support the hypothesis that the addition of laser depilation (which provides more permanent and effective depilation than other methods) to crystallized phenol treatment (a non-radical, minimally invasive method associated with very good cosmetic results) can increase the effectiveness of the treatment and also reduce the recurrence rate of the disease. 相似文献