全文获取类型
收费全文 | 915篇 |
免费 | 70篇 |
国内免费 | 70篇 |
专业分类
电工技术 | 2篇 |
综合类 | 24篇 |
化学工业 | 414篇 |
金属工艺 | 56篇 |
机械仪表 | 54篇 |
建筑科学 | 20篇 |
能源动力 | 1篇 |
轻工业 | 229篇 |
石油天然气 | 5篇 |
无线电 | 24篇 |
一般工业技术 | 118篇 |
冶金工业 | 63篇 |
原子能技术 | 15篇 |
自动化技术 | 30篇 |
出版年
2024年 | 14篇 |
2023年 | 30篇 |
2022年 | 96篇 |
2021年 | 115篇 |
2020年 | 53篇 |
2019年 | 48篇 |
2018年 | 43篇 |
2017年 | 36篇 |
2016年 | 51篇 |
2015年 | 38篇 |
2014年 | 51篇 |
2013年 | 67篇 |
2012年 | 57篇 |
2011年 | 48篇 |
2010年 | 30篇 |
2009年 | 44篇 |
2008年 | 38篇 |
2007年 | 29篇 |
2006年 | 34篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 17篇 |
2002年 | 11篇 |
2001年 | 20篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1961年 | 2篇 |
排序方式: 共有1055条查询结果,搜索用时 15 毫秒
61.
《Food Control》2016
In this study, a molecularly imprinted polymer solid phase extraction method combining high performance liquid chromatography was developed to determine the residues of tetracycline drugs in animal derived foods. The polymer was synthesized with chlortetracycline as template molecule, methacrylic acid as functional monomer at template/monomer ratio of 1:4. The prepared solid phase extraction column was able to capture four tetracyclines simultaneously with high adsorption capacities (3560–4700 ng) and high recoveries (>87%), and was able to be reused for at least thirty times. The limits of detection were in a range of 20–40 ng/g, and the recoveries from fortified blank samples (milk, egg and pork) were in a range of 74%–93%. Furthermore, the polymer-based column achieved better purification effect than three commercial solid phase extraction columns. This is the first study reporting the use of chlortetracycline based molecularly imprinted polymer for determination of tetracyclines in animal derived foods. 相似文献
62.
从流行病学、临床症状、病理变化和实验室检验四个方面对鸡传染性喉气管炎进行了诊断,并做了药物治疗对比试验.结果表明,杀病毒药(消毒王)加清热解毒、止咳平喘中草药配合治疗鸡传染性喉气管炎,效果更好,能较快地制止病鸡死亡,显著降低死亡率及减少药物治疗费用. 相似文献
63.
Investigating the chlorination of acidic pharmaceuticals and by-product formation aided by an experimental design methodology 总被引:1,自引:0,他引:1
José Benito Quintana Rosario Rodil Purificación López-Mahía Soledad Muniategui-Lorenzo 《Water research》2010,44(1):243-255
The degradation of seven acidic drugs and two metabolites during chlorination was investigated by liquid chromatography-mass spectrometry (LC-MS). A triple-quadrupole (QqQ) system was used to follow the time course of the pharmaceuticals and by-products, while a quadrupole time-of-flight (Q-TOF) system was also used for the identification of the by-products. Under strong chlorination conditions (10 mg/L Cl2, 24 h), only four of the target compounds were significantly degraded: salicylic acid, naproxen, diclofenac and indomethacine. The degradation kinetics of these four compounds were investigated at different concentrations of chlorine, bromide and pH by means of a Box-Behnken experimental design. Depending on these factors, measured pseudo-first order half-lives were in the ranges: 23-573 h for salicylic acid, 13-446 min for naproxen, 5-328 min for diclofenac and 0.4-13.4 min for indomethacine. Also, it was observed that chlorine concentration was the overall most significant factor, followed by the bromide concentration (except for indomethacine), resulting in increased degradation kinetics as they are increased. The degradation path of salicylic acid, naproxen and diclofenac consisted of aromatic substitution of one or two hydrogens by chlorine and/or bromide. Moreover, for diclofenac, two other by-products corresponding to a decarboxylation/hydroxylation pathway from the monohalogenated products were also identified. On the other hand, indomethacine degradation did not lead to halogenation products but to oxidation ones. The investigation of these by-products in real samples by LC-MS/MS (QqQ) showed that the halogenated derivates of salicylic acid occurred in all the drinking water and wastewater samples analysed. 相似文献
64.
药品安全直接关系到病人的生命健康,国家已出台严厉的打击措施,但假药问题仍屡禁不止,其中一个主要原因是缺少相应的技术手段对药品进行防伪管理。本文基于可信二维码,结合药品实际流通过程,为药品提供了一个安全可信的防伪系统,实现对制造商、经销商、药品本身的合法性认证,确实解决了药品防伪问题。 相似文献
65.
66.
Jenkins RE Meng X Elliott VL Kitteringham NR Pirmohamed M Park BK 《Proteomics. Clinical applications》2009,3(6):720-729
Flucloxacillin is a synthetic penicillin used in the treatment of Staphylococcal infections. Adverse reactions to the drug are believed to arise through covalent modification of proteins, with tissue damage occurring secondary to an immune reaction. Serum proteins have been shown by adduct-specific antibodies to be modified by flucloxacillin, but the nature and sites of modification have not been characterised. Here, in vitro studies on HSA have shown by MS that the modification of protein lysine residues occurs in a dose-, time- and site-dependent manner. Affinity, cation exchange and reversed phase chromatography prior to MS revealed in vivo modification of HSA with flucloxacillin in tolerant patients, with up to nine modified lysine residues being detected in each patient, and with modification of Lys190 and Lys212 being detected in 8/8 patients. It was also revealed for the first time that plasma proteins could be modified with the 5-hydroxymethyl metabolite of flucloxacillin, and that essentially the same Lys residues were targeted by both the parent drug and its metabolite. This study provides a detailed characterisation of sites of chemical modification of an endogenous target and reveals candidate peptides for T-cell and antibody assays of flucloxacillin hypersensitivity. 相似文献
67.
Tomoko I. Hooper Samar F. DeBakey Stephanie Pratt 《Accident; analysis and prevention》2010,42(1):261-268
The authors examined the association between prescribed medications and fatal motor vehicle crashes (MVCs) in an active duty military population between 2002 and 2006. Using a case-control design, MVC deaths were ascertained using a military mortality registry, and an integrated health system database provided information on health system eligibility, pharmacy transactions, and medical encounters. Cases and controls were matched on comparable observation time outside periods of deployment. Among selected categories, only one, antidepressant medications, was an independent predictor of fatal MVC (odds ratio, 3.19; 95% confidence interval, 1.01-10.07). Male gender, Black race, enlisted rank, service branch (Navy and Marine Corps), and selected co-morbidities were also independent predictors. Unexpectedly, the odds of younger age quartiles (<27 years) and history of deployment were reduced for MVC cases. Although results need to be considered in the context of data limitations, the association between prescribed antidepressants and fatal MVC may reflect unmeasured co-morbidities, such as combined effects of prescribed and over-the-counter medications and/or alcohol or other substance abuse. Younger individuals, representing new military accessions in training or returning from deployment with serious injuries, may have fewer opportunities to operate vehicles, or targeted efforts to reduce MVC following deployment may be showing a positive effect. 相似文献
68.
Shuangshuang Song Baocheng Tian Fen Chen Wenji Zhang Yusheng Pan Qiang Zhang 《Drug development and industrial pharmacy》2015,41(1):51-62
Objective: The objectives of this study were, first, to develop a free-flowing and stable proniosome formulation for poorly water-soluble drugs such as vinpocetine; and second, to estimate its bioavailability as oral drug delivery system.Methods: The proniosomes consisting of span60, cholesterol, sorbitol and vinpocetine were prepared by a novel approach. After the proniosomes were contacted with water, the suspension of vinpocetine-loaded niosomes formed automatically. The proniosomes and reconstituted niosomes were evaluated for their physicochemical characteristics, in vitro drug dissolution and release, integrity and stability at different GI tract pH conditions, in situ single-pass intestinal perfusion and in vivo bioavailability.Results: The proniosome powder exhibited excellent flowability. The reconstituted niosomes with high drug entrapment efficiency (89.67?±?3.28%) showed spherical morphology with smooth surface under transmission electron microscope (TEM). X-ray diffraction (XRD) indicated that the drug was in an amorphous or molecular state in proniosome powder. In vitro dissolution and release study, proniosomes did enhance the dissolution and release rate compared to vinpocetine suspension in phosphate buffer solution (pH 7.2). Proniosome-derived niosomes could keep their integrity and stability at different GI tract pH conditions. The in situ single-pass intestinal perfusion indicated that encapsulation of vinpocetine into niosomes could largely improved the absorption of vinpocetine. The AUC(0?∞) of F2 and F3 was about 4.0- and 4.9-fold higher than that of the vinpocetine suspension, respectively. The results demonstrated the proniosomes indeed remarkably enhanced the oral bioavailability of vinpocetine.Conclusion: This study suggested the potential of proniosomes as stable precursors for the immediate preparation of niosome carrier systems. 相似文献
69.
Nanoelectromechanical Chip (NELMEC) Combination of Nanoelectronics and Microfluidics to Diagnose Epithelial and Mesenchymal Circulating Tumor Cells from Leukocytes 下载免费PDF全文
Seied Ali Hosseini Mohammad Abdolahad Somayeh Zanganeh Mahyar Dahmardeh Milad Gharooni Hamed Abiri Alireza Alikhani Shams Mohajerzadeh Omid Mashinchian 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(7):883-891
An integrated nano‐electromechanical chip (NELMEC) has been developed for the label‐free distinguishing of both epithelial and mesenchymal circulating tumor cells (ECTCs and MCTCs, respectively) from white blood cells (WBCs). This nanoelectronic microfluidic chip fabricated by silicon micromachining can trap large single cells (>12 µm) at the opening of the analysis microchannel arrays. The nature of the captured cells is detected using silicon nanograss (SiNG) electrodes patterned at the entrance of the channels. There is an observable difference between the membrane capacitance of the ECTCs and MCTCs and that of WBCs (measured using SiNG electrodes), which is the key indication for our diagnosis. The NELMEC chip not only solves the problem of the size overlap between CTCs and WBCs but also detects MCTCs without the need for any markers or tagging processes, which has been an important problem in previously reported CTC detection systems. The great conductivity of the gold‐coated SiNG nanocontacts as well as their safe penetration into the membrane of captured cells, facilitate a precise and direct signal extraction to distinguish the type of captured cell. The results achieved from epithelial (MCF‐7) and mesenchymal (MDA‐MB231) breast cancer cells circulated in unprocessed blood suggest the significant applications for these diagnostic abilities of NELMEC. 相似文献
70.