首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   195篇
  免费   12篇
  国内免费   17篇
  2024年   1篇
  2023年   3篇
  2022年   1篇
  2021年   4篇
  2020年   4篇
  2019年   12篇
  2018年   20篇
  2017年   14篇
  2016年   1篇
  2015年   2篇
  2014年   6篇
  2013年   14篇
  2012年   9篇
  2011年   5篇
  2010年   7篇
  2009年   5篇
  2008年   9篇
  2007年   5篇
  2006年   10篇
  2005年   7篇
  2004年   5篇
  2003年   5篇
  2002年   2篇
  2001年   2篇
  2000年   3篇
  1999年   6篇
  1998年   6篇
  1997年   1篇
  1996年   4篇
  1994年   7篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1987年   2篇
  1985年   2篇
  1984年   4篇
  1983年   6篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1977年   5篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   5篇
排序方式: 共有224条查询结果,搜索用时 31 毫秒
171.
摘要 目的:探讨肺炎3号联合金银花治疗儿童肺炎对患儿呼吸功能和炎症反应水平影响。方法:选取我院2017年2月-2019年4月期间收治的80例肺炎患儿,随机分成对照组和观察组,每组40例,对照组患儿采取阿奇霉素治疗,观察组患儿采取肺炎3号联合金银花治疗,对比不同治疗方法对患儿呼吸功能和炎症反应水平影响。结果:两组患儿治疗前用力肺活量(forced vital capacity,FVC)、第1秒用力呼气容积(orced expiratory volume in 1 second,FEV1)、用力呼气峰流速(expiratory peak flow rate,PEF)对比无统计学差异(P>0.05),治疗后,观察组患儿上述肺功能指标均明显高于对照组(P<0.05)。两组治疗前患儿血清肿瘤坏死因子(tumor necrosis factor-α,TNF-α)、白介素(interleukin,IL)-6、IL-10对比无统计学差异(P>0.05),治疗后,观察组患儿TNF-α、IL-6均明显低于对照组,且观察组IL-10明显高于对照组(P<0.05)。患儿啰音消失时间、止咳时间、气促消失时间、热退时间以及住院时间对比发现对照组明显长于观察组(P<0.05)。在治疗总效率方面,观察组明显更高(P<0.05)。结论:儿童肺炎采取肺炎3号联合金银花治疗效果确切,可明显改善患儿呼吸功能,抑制机体炎性细胞因子,有效改善患儿临床症状,具有一定临床意义。  相似文献   
172.
Akin M  Turgut S  Ayada C  Polat Y  Balci YI  Erdoğan F 《Gene》2011,487(1):80-83
The current study was conducted to assess 3435C>T multidrug resistance 1 gene polymorphism and the efficacy of high dose methylprednisolone (HDMP) in childhood acute idiopathic thrombocytopenic purpura patients.

Methods

A total of 31 childhood acute Idiopathic thrombocytopenic purpura patients (17 females, 14 males) between the ages of 2 and 16 years of age were included in the study. High-dose methylprednisolone was given at a dose of 30 mg/kg/day for 3 days and 20 mg/kg/day for 4 days, consecutively and intravenously. Polymerase chain reaction-restriction fragment length polymorphism was used for the detection of C3435T single nucleotide polymorphism. Fragments obtained were 238 bp to T/T genotype, 172 bp and 60 bp fragments to the C/C genotype, and 238 bp, 172 bp and 60 bp to the C/T genotype.

Results

The distribution of CC, CT, and TT genotypes were 19.0%, 61.3%, and 19.4%, respectively. Both allele frequencies of C and T were the same — 50%. There was no significant difference in genotype and allele distribution between the patients with ITP and the control group (χ2 = 0.84 p = 0.65, χ2 = 0.2 p = 0.63, respectively). There were no significant differences in age, gender, and pre- and post-treatment platelet counts between CC, CT, and TT genotypes of the MDR gene. Response to treatment shows no significant difference between genotype and allele groups.

Conclusion

In our study, there was no difference in the HDMP treatment response between MDR1 gene genotypes. However, it should be noted that this study includes a small group of patients. Our data should therefore be considered preliminary, awaiting further confirmatory studies on an expanded patient base.  相似文献   
173.
Since multiresistant bacterial strains are more widespread and the victim numbers steadily increase, it is very important to possess a broad bandwidth of antimicrobial substances. Antibiotics often feature membrane-associated effect mechanisms. So, we present a membrane proteomic approach to shed light on the cellular response of Escherichia coli as model organism to the hexapeptide MP196, which is arginine and tryptophan rich. Analyzing integral membrane proteins are still challenging, although various detection strategies have been developed in the past. In particular, membrane proteomics in bacteria have been conducted very little due to the special physical properties of these membrane proteins. To obtain more information on the cellular response of the new compound group of small peptides, the tryptophan- and arginine-rich hexapeptide MP196 was subject to a comprehensive quantitative membrane proteomic study on E. coli by means of metabolic labeling in combination with membrane lipid analyses. This study provides in total 767 protein identifications including 185 integral membrane proteins, from which 624 could be quantified. Among these proteins, 134 were differentially expressed. Thereby, functional groups such as amino acid and membrane biosynthesis were affected, stress response could be observed, and the lipid composition of the membrane was significantly altered. Especially, the strong upregulation of the envelope stress induced protein. Spy indicates membrane damage, as well as the downregulation of the mechano-sensitive channel MscL beside others. Finally, the exceptional downregulation of transport systems strengthens these findings.  相似文献   
174.
175.
The use of natural products by communities from the Colombian Caribbean region to treat health issues, together with biodiversity and geographical features, constitute a great scenery to develop new therapies based on ethnopharmacological heritage. Here, we investigated the anti-inflammatory potential of 10 commonly used plants in Colombian folk medicine, evaluating their effect on nitric oxide (NO) production by LPS-stimulated RAW 264.7 macrophages. The most active plant was evaluated in vivo using 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced mouse ear edema, along with its effect on the production of pro-inflammatory mediators in vitro. The extract of Physalis angulata L. calyces showed the highest activity. This extract was fractionated and its dichloromethane fraction (DF) was the most active in vitro, inhibiting the production of NO, prostaglandin E2 (PGE2), interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and monocyte chemotactic protein (MCP)-1 (CCL2). In vivo, DF showed a significant inhibition of ear edema and myeloperoxidase (MPO) activity, with evident reduction of the leukocyte infiltration into tissue. Our results support the ethnopharmacological use of the selected plants in folk medicine. P. angulata dichloromethane fraction represents a promising source of pharmacological compounds with great potential therapeutic use to treat inflammatory illness.  相似文献   
176.
ObjectiveThe present study aims to simulate an alarm system for online detecting normal electrocardiogram (ECG) signals from abnormal ECG so that an individual's heart condition can be accurately and quickly monitored at any moment, and any possible serious dangers can be prevented.Materials and methodsFirst, the data from Physionet database were used to analyze the ECG signal. The data were collected equally from both males and females, and the data length varied between several seconds to several minutes. The heart rate variability (HRV) signal, which reflects heart fluctuations in different time intervals, was used due to the low spatial accuracy of ECG signal and its time constraint, as well as the similarity of this signal with the normal signal in some diseases. In this study, the proposed algorithm provided a return map as well as extracted nonlinear features of the HRV signal, in addition to the application of the statistical characteristics of the signal. Then, artificial neural networks were used in the field of ECG signal processing such as multilayer perceptron (MLP) and support vector machine (SVM), as well as optimal features, to categorize normal signals from abnormal ones.ResultsIn this paper, the area under the curve (AUC) of the ROC was used to determine the performance level of introduced classifiers. The results of simulation in MATLAB medium showed that AUC for MLP and SVM neural networks was 89.3% and 94.7%, respectively. Also, the results of the proposed method indicated that the more nonlinear features extracted from the ECG signal could classify normal signals from the patient.ConclusionThe ECG signal representing the electrical activity of the heart at different time intervals involves some important information. The signal is considered as one of the common tools used by physicians to diagnose various cardiovascular diseases, but unfortunately the proper diagnosis of disease in many cases is accompanied by an error due to limited time accuracy and hiding some important information related to this signal from the physicians' vision leading to the risks of irreparable harm for patients. Based on the results, designing the proposed alarm system can help physicians with higher speed and accuracy in the field of diagnosing normal people from patients and can be used as a complementary system in hospitals.  相似文献   
177.
During plant tissue culture, the culture container is small and sealed; the concentration of CO2 in the microenvironment is relatively low. The plantlet growth is restrained for the shortage of CO2 in the culture container. Carbonic anhydrase is a zinc-containing metalloenzyme that catalyzes the reversible conversion of bicarbonate to CO2. The determination of carbonic anhydrase of leaves from Atractylodes lancea (thunb.) DC, Orychophragmus violaceus (L.) O.E. Schulz, Brassica juncea (L.) Czern.et Coss. cv. Luzhousileng, Brassica campestris L. cv. Chuanyou No.8, Brassica napus L cv. Oro, Brassica carinata Braun, Raphanus sativa L. var. raphanistroides Makino and their plantlets indicates that the carbonic anhydrase activity of leaves from both plantlets and fields varies from plant species to plant species, the carbonic anhydrase activity of leaves of Atractylodes lancea (thunb.) DC is the lowest among those plants, and the leaves of all plantlets are lower in carbonic anhydrase activity than the same species of plants from fields. The comparison of the growth rates of those plantlets shows that their relative growth rates are significantly different, plantlets of Atractylodes lancea have the slowest relative growth rate among those plants, and plantlets of Brassica juncea have the greatest relative growth rate. The relationship between RGR of plantlets and their CA activities is a significant linear function. It seems that there was certain correlation between carbonic anhydrase activities of plants and their growth rates. It suggests that in vitro, the greater the carbonic anhydrase activity of plantlet is, the higher its net photosynthetic rate, and the faster its growth rate. Those results offer a foundation to a rational medium choice in plant tissue culture.  相似文献   
178.
We have investigated the induction of sister-chromatid exchanges (SCEs) in 9L rat brain tumor cells treated with the alkylating agent 1-ethyl-1-nitrosourea (ENU) and 3-(4-amino-2-methyl-5-pyrimidinyl)methyl-1-(2-chloroethyl)-1-nitrosourea (ACNU), an agent that both alkylates and crosslinks DNA. Induction of SCEs by ACNU was found to be 143-fold greater than for ENU. However, on an equimolar basis, the alkylation of DNA by 14C-ACNU was approximately 3.2-fold higher than for 14C-ENU. After correction for this difference was made, the induction of SCEs by ACNU was calculated to be 45-fold greater than for ENU. While DNA alkylation products formed by ACNU and ENU are similar, the chloroethyl alkylation product(s) of ACNU can form DNA-interstrand crosslinks; the ethyl alkylation product(s) of ENU cannot. Based on these findings, we propose that the increased induction of SCEs caused by ACNU is a result of the formation of DNA interstrand crosslinks.  相似文献   
179.
 为了进一步证实某些药物对红细胞膜稳定(即抗溶血)作用及抑制CaM功能与药理作用之间的相关性,本文选用丹参酮Ⅱ-A磺酸钠,戊脉安,奎尼丁和莨菪类药物,测定它们对大鼠红细胞溶血及CaM功能的影响。结果表明丹参酮Ⅱ-A磺酸钠,戊脉安,奎尼丁对红细胞溶血抑制率分别为100%,71%,32%,对CaM功能的抑制分别为71.8%,63.4%,46.4%。莨菪类药物有促溶血作用,对CaM功能的抑制也极弱。我们还发现以上药物对膜上Ca~(2+)+Mg~(2+)-ATP酶的直接作用亦有类似的规律。这种相关性可能与膜表面CaM与钙离子,靶酶及药物结合区的疏水性及药物本身的相对疏水性有关。  相似文献   
180.
To study general stimulatory effects of 1,25-dihydroxyvitamin D3 on intestinal protein synthesis, slices of duodenal villi from 1,25-dihydroxyvitamin D3-treated and vitamin D-deficient rats were incubated in vitro for 90 min at the surface of medium containing [3H]leucine. Incorporation of the [3H]leucine into TCA-precipitated protein, which was shown to be linear for 12 h and 90% inhibited by cycloheximide, was increased by 50-60% at 26 h after a single injection of 125 ng of 1,25-dihydroxyvitamin D3 (three experiments, P less than 0.001). The increase, which was not due to circadian rhythm fluctuations of the intestine, was in synchrony with the second Ca2+ transport response observed by Halloran and DeLuca (Arch. Biochem. Biophys. 208, 477-486, 1981). However, no significant difference in [3H]leucine incorporation was observed before or during the initial Ca2+ transport response observed by Halloran and DeLuca, i.e., at 1.0, 3.0, and 6.5 h following an injection of 1,25-dihydroxyvitamin D3. The late onset of the 1,25-dihydroxyvitamin D3-induced increase in total protein synthesis implies that it is an indirect rather than a direct effect of the hormone.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号