全文获取类型
收费全文 | 790篇 |
免费 | 31篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 32篇 |
2021年 | 37篇 |
2020年 | 20篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 28篇 |
2015年 | 36篇 |
2014年 | 45篇 |
2013年 | 63篇 |
2012年 | 66篇 |
2011年 | 75篇 |
2010年 | 31篇 |
2009年 | 33篇 |
2008年 | 42篇 |
2007年 | 40篇 |
2006年 | 31篇 |
2005年 | 26篇 |
2004年 | 31篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有821条查询结果,搜索用时 31 毫秒
701.
Hfaïedh N Allaqui MS Croute F Soleilhavoup JP Jammoussi K Makni Ayadi F Kammoun A El Feki A 《Comptes rendus biologies》2005,328(7):648-660
This study has been undertaken with the aim of determining if intermittent fasting can be considered as a malnutrition that amplifies, according to numerous authors, the cytotoxic effects of environmental pollutants. We have used 200 male and female rats of 'Wistar' descent (BW approximately 180 g). These rats are distributed into two groups: some nourished daily (N) and others nourished one day over two (J) during a month. By the end of this month, each group is itself split into two subgroups, the first one receiving tap water as drinkable water (group NO and JO); the other one receiving the water enriched by the chloride of nickel at the rate of 100 mg NiCl2 per litre (groups NNi and JNi). Intermittent fasting goes on parallel to treatment during 2, 4, 10, 16, 30 and 60 days. For the exploration of the protein of stress (HSP) and of the metallothioneines (MT), the nickel is administered by injection at the rate of 4 mg NiCl2 per kg during 1 and 5 days. Our results show that the mineral seric and renal balance does not vary in conditions of intermittent fasting compared with conditions of normal nutrition. Our study show than that nickel induced a renal deficiency by decreasing the creatinemia and uraemia rate, which is confirmed by the histological study, and induced a decrease in the induction of the HSP73 and in the synthesis of the (MT). The association of nickel with intermittent fasting would inhibit these effects. In conclusion, intermittent fasting does not manifest itself as a malnutrition that amplifies the nickel's effects. Nevertheless, it seems that the calorific lack provoked by intermittent fasting is beneficial to the body by increasing its performances against the cytotoxic effects induced by nickel. 相似文献
702.
Three new polyhydroxypregnane glycosides named alpinoside A [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside], alpinoside B [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-thevetopyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside], and alpinoside C [kidjolanin 3-O-beta-d-glucopyranosyl-(1-->4)-beta-d-glucopyranosyl-(1-->4)-beta-d-oleandropyranosyl-(1-->4)-beta-d-cymaropyranosyl-(1-->4)-beta-d-cymaropyranoside] were isolated from the leaves of Oxystelma esculentum var. alpini. The structure elucidation was accomplished by extensive spectroscopic analysis and acid-catalyzed hydrolysis. 相似文献
703.
A general method for the preparation of substituted pyridazinopyrazolotriazines is reported. 3-Aminopyrazolo[3,4-d]pyridazine was diazotized and coupled with active methylene reagents to afford the tricyclic pyridazino[3',4':3,4]pyrazolo[5,1-c]-1,2,4-triazines with substituents such as methyl, phenyl, ethoxycarbonyl, acetyl or benzoyl, depending on the methylene reagent used. In addition several condensation reactions with hydrazines gave the corresponding acid hydrazide and/or hydrazones. Reactions of 3 with aromatic aldehydes afforded hydrazones. The products were screened for their antimicrobial activity against five microorganisms. 相似文献
704.
Aiad F El-Gamal B Al-Meer J El-Kerdasy Z Zakhary N El-Aaser A 《Journal of biochemistry and molecular biology》2004,37(3):370-375
There has been increasing interest in the value of using soybean to delay or reduce the tumor incidence. This study was undertaken to investigate the possible protective effects of soybean against hepatocarcinogenesis induced by DL-ethionine. Accordingly, we measured biochemical changes occurring in serum and liver of rats treated with DL-ethionine in the presence or absence of soybean. Male albino rats were fed a control diet containing the hepatocarcinogen, DL-ethionine, or the control diet plus soybean 30%, or the control diet plus soybean plus DL-ethionine 0.25% for three months and then returned to a control diet for up to nine months. Rats fed a control diet plus DL-ethionine showed a gradual decrease in liver DNA, RNA, total protein, and liver weight and enzyme activities of liver transaminases (GOT and GPT) and alkaline phosphatase over the 7-month study period. This was followed by a large increase in the liver parameters at the end of the 9(th) month, except for 5'-nucleotidase and glucose-6-phosphatase that showed a large decrease. On the other hand, a gradual increase in the serum enzyme activities of GOT, GPT, 5-nucleotidase, alkaline phosphatase, and in the albumin/globulin (A/G) ratio is observed in the group of rats fed a control diet plus DL-ethionine compared to the control group over 8 months, and this was followed by a large increase in all serum parameters studied at nine-months. The administration of 30% soybean to the rat diet in addition to DL-ethionine maintained all parameters studied at near control values until the end of the 9(th) month. This study suggests that soybean has a protective effect against the hepatocarcinogenesis induced by DL-ethionine. 相似文献
705.
A bacterial artificial chromosome library of Lotus japonicus constructed in an Agrobacterium tumefaciens-transformable vector 总被引:2,自引:0,他引:2
Men AE Meksem K Kassem MA Lohar D Stiller J Lightfoot D Gresshoff PM 《Molecular plant-microbe interactions : MPMI》2001,14(3):422-425
We constructed a BAC library of the model legume Lotus japonicus with a 6-to 7-fold genome coverage. We used vector PCLD04541, which allows direct plant transformation by BACs. The average insert size is 94 kb. Clones were stable in Escherichia coli and Agrobacterium tumefaciens. 相似文献
706.
Defne Gümüş Fatma Kalaycı-Yüksek Emre Yörük Gülşen Uz Eşref Çelik Cansu Arslan Elif Merve Aydın Cem Canlı Mine Anğ-Küçüker 《Folia microbiologica》2018,63(4):451-457
The host is the main environment for bacteria, and they also expose to many antibiotics during the treatment of infectious diseases in host body. In this study, it was aimed to investigate possible changes in growth rate and expression levels of three virulence genes (foc/foc, cnf1, and usp) in a uropathogenic E. coli standard strain within the presence of ciprofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole. The UPEC C7 strain was grown on tryptic soy broth-TSB (control), TSB + ciprofloxacin, TSB + nitrofurantoin, and TSB + trimethoprim-sulfamethoxazole for determination of both growth rate and gene expression level. Antibiotics were added according to their sub-minimal inhibition concentrations. E-test was used to determine MIC values of antibiotics. Growth changes were measured in absorbance 600 nm during 24-h period. Total RNA isolations were performed after incubation for 24 h at 37 °C. Gene expression levels were determined by quantitative PCR. Tukey’s post hoc test was used for statistical analysis. According to absorbance values, it has been shown that only ciprofloxacin and trimethoprim-sulfamethoxazole have lead significant decrease on growth rate. We also detected statistically significant differences in each gene expression levels for all antibiotics via relative quantification analysis. Fold changes in gene expression was found 0.65, 1.42, 0.23 for foc/foc gene; 0.01, 0.01, 2.84 for cnf1 gene; and 0.1, 0.01, 0.01 for usp gene in the presence of ciprofloxacin, nitrofurantoin, and trimethoprim/sulfamethoxazole, respectively. This investigation has shown that antibiotics can play a role as an environmental factor which may determine the pathogenicity of bacteria in vivo. 相似文献
707.
Sourour Neji Ines Hadrich Amine Ilahi Houaida Trabelsi Hedi Chelly Nadia Mahfoudh Fatma Cheikhrouhou Hayet Sellami Fattouma Makni Ali Ayadi 《Mycopathologia》2018,183(5):765-775
Background
The Candida parapsilosis complex species has emerged as an important cause of human disease. The molecular identification of C. parapsilosis isolates at the species level can be helpful for epidemiological studies and then for the establishment of appropriate therapies and prophylactic measures.Methods
The present study was undertaken to analyze 13 short tandem repeat (STR) markers (7 minisatellites and 6 microsatellites) in a global set of 182 C. parapsilosis complex isolates from different origins including invasive and superficial clinical sites.Results
Upon the analysis of 182 strains of C. parapsilosis complex species, 10–17 haplotypes were detected for each minisatellite marker. The combination of 7 minisatellite markers yielded 121 different genotypes with a 0.995 D value. Upon the analysis of 114 isolates (68 from invasive infections and 46 from superficial infections), 21–32 genotypes were detected for each microsatellite marker. The combination of all 13 markers yielded 96 different genotypes among 114 isolates with a high degree of discrimination (0.997 D value).The same multilocus genotype was shared by isolates recovered from some patients and from the hand of theirs correspondent healthcare worker. For another patient, the same multilocus genotype of C. metapsilosis was detected in blood and skin confirming that candidemia usually arises as an endogenous infection following prior colonization.Conclusions
These STR markers are a valuable tool for the differentiation of C. parapsilosis complex strains, to support epidemiological investigations especially studies of strain relatedness and pathways of transmission.708.
Firdos Fatma Sonam Verma Aisha Kamal Alka Srivastava 《Physiology and Molecular Biology of Plants》2018,24(1):115-123
Pesticides are a group of chemical substances which are widely used to improve agricultural production. However, these substances could be persistent in soil and water, accumulative in sediment or bio-accumulative in biota depending on their solubility, leading to different types of environmental pollution. The present study was done to assess the impact of pesticides-mancozeb and chlorpyrifos, via morphological and physiological parameters using Allium cepa test system. Phytotoxic effects of pesticides were examined via germination percentage, survival percentage, root and shoot length, root shoot length ratio, seedling vigor index, percentage of phytotoxicity and tolerance index. Oxidative stress on Allium seedlings caused by pesticides was also assessed by investigating the activity of antioxidative enzymes viz. catalase, peroxidase and superoxide dismutase. Correlation was worked out between morphological parameters and antioxidative enzymes to bring out the alliance between them. Mancozeb and chlorpyrifos concentrations were significantly and positively correlated with the activity of antioxidative enzymes and negatively correlated with morphological parameters. Significant positive correlation between various morphological parameters showed their interdependency. However, negative correlation was obtained between activity of antioxidative enzymes and morphological parameters. The enzymes however, showed positive correlation with each other. Based on our result we can conclude that all morphological parameters were adversely affected by the two pesticides as reflected by phytotoxicity in Allium. Their negative correlation with activity of antioxidative enzymes indicates that upregulation of antioxidative enzymes is not sufficient to overcome the toxic effect, thereby signifying the threat being caused by the regular use of these pesticides. 相似文献
709.
Eyup Avci Tuncay Kiris Aykan Çelik Eser Variş Fatma Kayaalti Esin Diyar Köprülü Hasan Kadi 《BMC cardiovascular disorders》2018,18(1):226
Background
The prognostic significance of changes in mean platelet volume (MPV) during hospitalization in ST segment elevation myocardial infarction (STEMI) patients underwent primary percutaneous coronary intervention (pPCI) has not been previously evaluated. The aim of this study was to determine the association of in-hospital changes in MPV and mortality in these patients.Methods
Four hundred eighty consecutive STEMI patients were enrolled in this retrospective study. The patients were grouped as survivors (n?=?370) or non-survivors (n?=?110). MPV at admission, and at 48–72?h was evaluated. Change in MPV (MPV at 48–72?h minus MPV on admission) was defined as ΔMPV.Results
At follow-up, long-term mortality was 23%. The non-survivors had a high ΔMPV than survivors (0.37 (??0.1–0.89) vs 0.79 (0.30–1.40) fL, p?<? 0.001). A high ΔMPV was an independent predictor of all cause mortality ((HR: 1.301 [1.070–1.582], p?=?0.008). Morever, for long-term mortality, the AUC of a multivariable model that included age, LVEF, Killip class, and history of stroke/TIA was 0.781 (95% CI:0.731–0.832, p?<? 0.001). When ΔMPV was added to a multivariable model, the AUC was 0.800 (95% CI: 0.750–0.848, z?=?2.256, difference p?=?0.0241, Fig. 1). Also, the addition of ΔMPV to a multivariable model was associated with a significant net reclassification improvement estimated at 24.5% (p?=?0.027) and an integrated discrimination improvement of 0.014 (p?=?0.0198).Conclusions
Rising MPV during hospitalization in STEMI patients treated with pPCI was associated with long-term mortality.710.
Chlorpyrifos (O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate), is an organophosphate insecticide effective against a broad spectrum of insect pests of economically important crops. The present study investigated the effects of chlorpyrifos application on sulfate assimilation and macro elemental composition in different plant parts at different phenological stages. Field experiments were conducted in the month of April 2008–2009. The individual plot size was 6 m2 (4 m × 1.5 m) having 4 rows with a row-to-row distance of 15 inches and plant to plant distance of 10 inches. The number of plants per m2 was 15. Seedlings were collected at 5 (preflowering), 10 (flowering) and 20 (postflowering) DAT (day after treatment) to analyze the effect of chlorpyrifos on APR activity and elemental composition. At harvest stage, seed from individual treatments were analyzed for sulfur containing amino acids like methionine and cysteine content. Twenty-day-old seedlings of Vigna radiata L. were subjected to chlorpyrifos at different concentrations ranging from 0 to 1.5 mM through foliar spray in the field condition. A significant increase (50% in cysteine content and 50–92% in methionine content) in sulfur containing amino acids at a higher dose rate of 1.5 mM was recorded in seeds, however the increased activity of adenosine 5-phosphosulfate reductase (APR), the key enzyme in sulfate assimilation was recorded in all the three parts of the plant (leaf, stem, root.). Transiently lower nitrogen, sulfur and carbon content in 0.6 and 1.5 mM chlorpyrifos application in V. radiata L. supports the inhibition of metabolic processes. However, reverse trend was exhibited at 0.3 mM for same parameters. These results suggest the stimulatory effects on sulfate assimilation in V. radiata L. while as inhibitory effects were prevalent on elemental composition. 相似文献