全文获取类型
收费全文 | 328篇 |
免费 | 17篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 83篇 |
金属工艺 | 1篇 |
机械仪表 | 6篇 |
建筑科学 | 18篇 |
能源动力 | 13篇 |
轻工业 | 118篇 |
水利工程 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 31篇 |
冶金工业 | 9篇 |
自动化技术 | 58篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 11篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 6篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 22篇 |
2012年 | 18篇 |
2011年 | 31篇 |
2010年 | 21篇 |
2009年 | 19篇 |
2008年 | 36篇 |
2007年 | 22篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 156 毫秒
341.
Andreu V Ferrer E Rubio JL Font G Picó Y 《The Science of the total environment》2007,378(1-2):124-129
Surfactants have one of the highest production rates of all organic chemicals. Non-ionic surfactants, especially alkylphenol ethoxylates, received most attention as precursors of estrogenic metabolic products generated during wastewater treatment. Alkylphenols (octyl and nonylphenol), alkylphenol polyethoxylates (APEOs), and alcohol ethoxylates (AEOs) have been determined in a Mediterranean forest soil (Mediterranean Rendzic Leptosol) amended with sludges from six waste water treatment plants (WWTPs) located in the Valencian Community. These compounds were isolated from soil by pressurized liquid extraction (PLE) using a mixture acetone-hexane (50:50 v/v), the extracts were cleaned up by solid-phase extraction (SPE) with C(18), and determined by liquid chromatography atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) using analytical standards for quantification. The method enabled high-reliable identification by monitoring the corresponding ammonium adduct [M+NH(3)](+) for AEOs and APEOs, and the deprotonated molecule [M-H](-) for octyl and nonylphenol. Recoveries, determined spiking soil samples at different concentrations, ranged from 89 to 94%, with limits of quantification from 1 to 100 microg kg(-1). Data obtained from a soil sample mixed with biosolids in the laboratory showed that these compounds are present at concentrations ranging from 0.02 to 5 mg kg(-1). According to these concentrations, levels of possible risk can be concluded for the presence of non-ionic surfactants in soil. However, further assessment will be necessary to establish the relationship between exposure and effect findings. 相似文献
342.
Ekins J Peters SM Jones YL Swaim H Ha T La Neve F Civera T Blackstone G Vickery MC Marion B Myers MJ Yancy HF 《Journal of food protection》2012,75(6):1107-1112
The U.S. Food and Drug Administration (FDA) has previously validated a real-time PCR-based assay that is currently being used by the FDA and several state laboratories as the official screening method. Due to several shortcomings to the assay, a multiplex real-time PCR assay (MRTA) to detect three ruminant species (bovine, caprine, and ovine) was developed using a lyophilized bead design. The assay contained two primer or probe sets: a "ruminant" set to detect bovine-, caprine-, and ovine-derived materials and a second set to serve as an internal PCR control, formatted using a lyophilized bead design. Performance of the assay was evaluated against stringent acceptance criteria developed by the FDA's Center for Veterinary Medicine's Office of Research. The MRTA for the detection of ruminant DNA passed the stringent acceptance criteria for specificity, sensitivity, and selectivity. The assay met sensitivity and reproducibility requirements by detecting 30 of 30 complete feed samples fortified with meals at 0.1 % (wt/wt) rendered material from each of the three ruminant species. The MRTA demonstrated 100 % selectivity (0.0 % false positives) for negative controls throughout the assessment period. The assay showed ruggedness in both sample selection and reagent preparation. Second and third analyst trials confirmed the quality of the written standard operating procedure with consistency of results. An external laboratory participating in a peer-verification trial demonstrated 100 % specificity in identifying bovine meat and bone meal, while exhibiting a 0.03 % rate of false positives. The assay demonstrated equal levels of sensitivity and reproducibility compared with the FDA's current validated real-time PCR assay. The assay detected three prohibited species in less than 1.5 h of total assay time, a significant improvement over the current real-time assay. These results demonstrated this assay's suitability for routine regulatory use both as a primary screening tool and as a confirmatory test. 相似文献
343.
Jenifer Masip Rosa Jorba Miguel Lpez-Dupla Pere Domingo Yolanda María Pacheco Graciano García-Pardo Esteban Martínez Consuelo Vilads Sergi Veloso Vernica Alba Montserrat Olona Francesc Vidal Frederic Gmez-Bertomeu Joaquim Peraire Anna Rull 《International journal of molecular sciences》2022,23(15)
Nuclear magnetic resonance (NMR)-based advanced lipoprotein tests have demonstrated that LDL and HDL particle numbers (LDL-P and HDL-P) are more powerful cardiovascular (CV) risk biomarkers than conventional cholesterol markers. Of interest, in people living with HIV (PLHIV), predictors of preclinical atherosclerosis and vascular dysfunction may be associated with impaired immune function. We previously stated that immunological non-responders (INR) were at higher CV risk than immunological responders (IR) before starting antiretroviral therapy (ART). Using Liposcale® tests, we characterized the lipoprotein profile from the same cohort of PLHIV at month 12 and month 36 after starting ART, intending to explore what happened with these indicators of CV risk during viral suppression. ART initiation dissipates the differences in lipoprotein-based CV risk markers between INR and IR, and only an increase in the number of HDL-P was found in INR + IR when compared to controls (p = 0.047). Interestingly, CD4+ T-cell counts negatively correlated with medium HDL-P concentrations at month 12 in all individuals (ρ = −0.335, p = 0.003). Longitudinal analyses showed an important increase in LDL-P and HDL-P at month 36 when compared to baseline values in both IR and INR. A proper balance between a proatherogenic and atherogenic environment may be related to the reconstitution of CD4+ T-cell count in PLHIV. 相似文献
344.
Yolanda Kleiner Dr. Christoph Pöverlein Jannike Klädtke Dr. Michael Kurz Henrik F. König Dr. Jonathan Becker Dr. Sanja Mihajlovic Dr. Florian Zubeil Dr. Michael Marner Prof. Dr. Andreas Vilcinskas Prof. Dr. Till F. Schäberle Prof. Dr. Peter Hammann Dr. Sören M. M. Schuler Dr. Armin Bauer 《ChemMedChem》2022,17(6):e202100644
Tuberculosis represents one of the ten most common courses of death worldwide and the emergence of multidrug-resistant M. tuberculosis makes the discovery of novel anti-tuberculosis active structures an urgent priority. Here, we show that (+)-floyocidin B representing the first example of a novel dihydroisoquinoline class of fungus-derived natural products, displays promising antitubercular hit properties. (+)-Floyocidin B was identified by activity-guided extract screening and its structure was unambiguously determined by total synthesis. The absolute configuration was deduced from a key synthesis intermediate by single crystal X-ray diffraction analysis. A hit series was generated by the isolation of further natural congeners and the synthesis of analogs of (+)-floyocidin B. Extensive biological and physicochemical profiling of this series revealed first structure-activity relationships and set the basis for further optimization and development of this novel antitubercular scaffold. 相似文献
345.
Ingrid Rivera-Íñiguez Karina González-Becerra Omar Ramos-Lopez Yolanda E. Peréz-Beltrán Marian S. Chagüén-Hernández Erika Martínez-López Edgar J. Mendivil 《Molecular nutrition & food research》2023,67(14):2200675
Dyslipidemias are known risk factors for chronic diseases. Precision nutrition interventions are designed according to characteristics, such as diet, phenotype, and genotype. This systematic review aims to define a panel of genetic variants associated with lipid abnormalities that could be later used in nutrigenetic intervention studies. A systematic review is conducted following the PRISMA-P. Studies published from January 2010 to December 2020 in English language and humans are included from PubMed and ScienceDirect databases. Articles that demonstrate a strong association between polymorphisms (single nucleotide variation) of genes involved in lipid metabolism and increased risk for dyslipidemia are included. A total of 3031 articles are screened, but only 51 articles fulfill the inclusion criteria. The genes included are FABP2, MTTP related to CM synthesis and secretion; LPL, LIPC involved in triglyceride hydrolysis; CETP, APOA1, LCAT, ABCA1, and APOA5 related to lipoprotein metabolism, and APOE, LDLR, SCARB1, APOC3 involved in lipid clearance. In this systematic review, genetic variants related to chylomicron synthesis, triglyceride hydrolysis, lipoprotein metabolism, and lipid clearance demonstrate a strong association with lipid abnormalities, which can be used to design precision nutrition interventions that may help to prevent and treat dyslipidemia effectively. 相似文献