全文获取类型
| 收费全文 | 601篇 |
| 免费 | 9篇 |
| 国内免费 | 2篇 |
学科分类
| 医药卫生 | 612篇 |
出版年
| 2022年 | 9篇 |
| 2021年 | 5篇 |
| 2020年 | 10篇 |
| 2019年 | 8篇 |
| 2018年 | 3篇 |
| 2017年 | 7篇 |
| 2016年 | 13篇 |
| 2015年 | 10篇 |
| 2014年 | 9篇 |
| 2013年 | 28篇 |
| 2012年 | 21篇 |
| 2011年 | 18篇 |
| 2010年 | 11篇 |
| 2009年 | 16篇 |
| 2008年 | 16篇 |
| 2007年 | 15篇 |
| 2006年 | 14篇 |
| 2005年 | 11篇 |
| 2004年 | 16篇 |
| 2003年 | 12篇 |
| 2002年 | 8篇 |
| 2001年 | 7篇 |
| 2000年 | 7篇 |
| 1999年 | 4篇 |
| 1998年 | 15篇 |
| 1997年 | 9篇 |
| 1996年 | 20篇 |
| 1995年 | 9篇 |
| 1994年 | 9篇 |
| 1993年 | 10篇 |
| 1992年 | 16篇 |
| 1991年 | 12篇 |
| 1990年 | 17篇 |
| 1989年 | 14篇 |
| 1988年 | 15篇 |
| 1987年 | 10篇 |
| 1986年 | 6篇 |
| 1985年 | 18篇 |
| 1984年 | 19篇 |
| 1983年 | 15篇 |
| 1982年 | 18篇 |
| 1981年 | 9篇 |
| 1980年 | 12篇 |
| 1979年 | 12篇 |
| 1978年 | 14篇 |
| 1977年 | 14篇 |
| 1976年 | 14篇 |
| 1975年 | 6篇 |
| 1973年 | 10篇 |
| 1972年 | 4篇 |
排序方式： 共有612条查询结果，搜索用时 15 毫秒
51.
During grilling of the roast beef the following heterocyclic aromatic amines were found: IQ = 200.6 ng 100 g−1, MeIQx = 719.8 ng 100 g−1, MeIQ = 532.9 ng 100 g−1, 4.8-diMeIQx = 755.4 ng 100 g−1, norharmane = 507.0 ng 100 g−1, harmane = 1952.6 ng 100 g−1, Phe-P 1 = 263.7 ng 100 g−1, Trp-P 2 = 559.2 ng 100 g−1, PhIP = 1179.8 ng 100 g−1 and AαC = 51.7 ng 100 g−1. Their content was tested by using the method based on alkaline hydrolysis of the sample and the method based on solvent extraction of the grilled meat samples at different temperatures (without hydrolysis). The study showed that the heterocyclic aromatic amines produced during the grilling of beef are in a free form and chemically or physico-chemically bonded. The chemical forms of HAA formed in food have never been studied. For the purpose of the partial confirmation that HAA may be chemically or physico-chemically bonded, grilled beef samples were digested in vitro in model segments of the human digestive tract. Digestive enzymes, particularly proteolytic enzymes caused a statistically significant increase of free HAA determined by using solvent extraction without prior chemical hydrolysis of the sample. 相似文献
52.
Ch. Sarbach N. Yagoubi J. Sauzieres Ch. Renaux D. Ferrier E. Postaire 《International journal of pharmaceutics》1996,140(2):169-174
Plastics materials are commonly used in the packaging of pharmaceutical products, especially for the parenteral solutions. Thereby, the study of the compatibility of these containers with different contents is required for drug registration. This paper describes the migration phenomena which occurred between a tri-laminated film and a parenteral solution of metronidazole at 0.5%. The main migration products found in the solution were -caprolactam and a phthalic derivative. Several non-identified compounds were separated, coming from the polyurethane adhesive. However the aromatic amines were not detected. Thereby, it is important to study the compatibility of these containers with different contents. In addition, we have disclosed traces of butylhydroxytoluene, which constitute a degradation product of Irganox 1010 (phenolic antioxidant). 相似文献
53.
54.
A number of secondary and tertiary amines bearing 2-chloro-6-methylquinoline were synthesized by nucleophilic substitution reaction of 3-(chloromethyl)-2-chloro-6-methylquinoline with substituted aromatic primary and secondary amines in presence of catalytic amount of triethylamine (TEA) and K(2)CO(3). All the compounds were characterized by combined use of IR, (1)H-NMR, (13)C-NMR, mass spectral data, and microanalyses. The newly synthesized quinolinyl amines were screened in vitro for their antifungal activity against Aspergillus niger MTCC 281, Aspergillus flavus MTCC 277, Monascus purpureus MTCC 369, Penicillium citrinum NCIM 768 and for antibacterial activity strains viz. Escherichia coli NCTC 10418, Staphylococcus aureus NCTC 65710, and Pseudomonas aeruginosa NCTC 10662 by agar diffusion technique. Results of the preliminary screening revealed that some of the compounds mainly those with electron withdrawing groups in the phenyl ring showed promising antifungal activity. 相似文献
55.
Alguacil J Pfeiffer RM Moore LE Del Fresno MR Medina-Lopez R Kogevinas M Vermeulen R Dosemeci M Silverman DT Rothman N García-Closas M 《European journal of epidemiology》2007,22(2):91-98
Methods for efficiently identifying subjects with constantly acidic pH in epidemiological and clinical studies have not been assessed. We recruited 30 volunteers to estimate the minimum number of urine pH measurements using pH strips needed to identify subjects with "constantly acidic urine pH". Spearman's correlation coefficients between urine pH measured with a pH meter and with the four pH strips ranged from 0.94 to 0.95 (p < 0.001 for all four strips). Overall agreement within +/-0.5 pH units between the four strips and the pH meter ranged from 62.2% to 74.4%. When using a spot urine sample from a single morning to classify participants with respect to their urine pH, 80% of individuals fell into the acidic urine pH (pH equal to or lower than 6.0) group. When we required subjects to have urine pH equal to or lower than 6.0 in six consecutive AM spot urine samples and seven spot PM urine samples, only 20% of participants fulfilled this criterion. Measuring urine pH twice a day (early in the morning and early in the evening) during four consecutive days classified individuals in the same way as two daily measurements for one week. A single pH measurement from a spot urine sample is not reliable to identify individuals with constantly acidic pH. Morning and evening urine pH measurements with pH strips during four consecutive days identify individuals with constantly acidic urine pH individuals as well as one week of measurements, and thus might be useful to identify subjects with constantly acidic urine pH in epidemiological and clinical studies. 相似文献
56.
《Drug metabolism reviews》2012,44(3):486-527
Drugs for allergy are often taken in combination with other drugs, either to treat allergy or other conditions. In common with many pharmaceuticals, most such drugs are subject to metabolism by P450 enzymes and to transmembrane transport. This gives rise to considerable potential for drug-drug interactions, to which must be added consideration of drug-diet interactions. The potential for metabolism-based drug interactions is increasingly being taken into account during drug development, using a variety of in silico and in vitro approaches. Prediction of transporter-based interactions is not as advanced. The clinical importance of a drug interaction will depend upon a number of factors, and it is important to address concerns quantitatively, taking into account the therapeutic index of the compound. 相似文献
57.
Bo Wei Longbin Chen Rongrong Hu Ben Zhong Tang 《Macromolecular chemistry and physics.》2023,224(5):2200399
Poly(tetrahydropyrimidine)s are promising heterocyclic polymers with unique biocompatibility, antibacterial ability, inherent fluorescence property, and so on, whose development is limited by their synthetic approaches. Multicomponent polymerizations (MCPs) are a group of powerful tools for the facile construction of heterocyclic polymers from simple monomers. Herein, a catalyst-free multicomponent tandem polymerization of aliphatic diamines, activated alkyne, and formaldehyde was developed at 60 °C in methanol in air to construct poly(tetrahydropyrimidine)s with well-defined structures, high molecular weights (Mw up to 57700 g mol−1), high yields (up to 84%), and satisfactory thermal stability. The MCP was featured with commercially available monomers, high efficiency, catalyst-free economic and mild condition, which was applicable to aliphatic diamines with complicated chemical reactivity, providing a robust and efficient approach for the synthesis of diversified heterocyclic polymers such as poly(tetrahydropyrimidine)s. 相似文献
58.
Natalia L. Kononenko Sergej Hartfil Julia Willer Jessica Ferch Heike Wolfenberg Hans-Joachim Pflüger 《The Journal of comparative neurology》2019,527(6):1027-1038
In this study, we describe a cluster of tyraminergic/octopaminergic neurons in the lateral dorsal deutocerebrum of desert locusts (Schistocerca gregaria) with descending axons to the abdominal ganglia. In the locust, these neurons synthesize octopamine from tyramine stress-dependently. Electrophysiological recordings in locusts reveal that they respond to mechanosensory touch stimuli delivered to various parts of the body including the antennae. A similar cluster of tyraminergic/octopaminergic neurons was also identified in the American cockroach (Periplaneta americana) and the pink winged stick insect (Sipyloidea sipylus). It is suggested that these neurons release octopamine in the ventral nerve cord ganglia and, most likely, convey information on arousal and/or stressful stimuli to neuronal circuits thus contributing to the many actions of octopamine in the central nervous system. 相似文献
59.
The ICH M7 Guideline requires low level control of mutagenic impurities in pharmaceutical products to minimize cancer risk in patients (ICHM7, 2014). Bacterial mutagenicity (Ames) data is generally used to determine mutagenic and possible carcinogenic potential of compounds. Recently, a publication on experiences of using two in silico systems to identify potentially mutagenic impurities highlighted the importance of performing a critical review of published Ames data utilized as part of a mutagenicity assessment of impurities (Greene et al., 2015). Four compounds (2-amino-5-hydroxybenzoic acid, 2-amino-3-chlorobenzoic acid, methyl 2-amino-4-chlorobenzoate and 4-morpholinopyridine) reported mutagenic were identified in a two system in silico assessment and expert review of the structuresas non-mutagenic. Likely reasons for mutagenicity could not be identified and the purity of the compounds tested was proposed. In the current investigation, the purest available sample of the four compounds was tested in an OECD-compliant Ames test. The compounds were all found to be non-mutagenic. Possible reasons for the discrepancy between previously reported and current results are discussed. Additionally, important points to consider when conducting an expert review of available Ames data are provided particularly in cases where reported Ames results are discrepant with a two system in silico assessment. 相似文献
60.
Katja Hofmann Isabelle Roth Stefan Spange 《Macromolecular chemistry and physics.》2012,213(16):1639-1642
