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   5238篇
  免费   269篇
  国内免费   33篇
耳鼻咽喉   157篇
儿科学   75篇
妇产科学   260篇
基础医学   646篇
口腔科学   50篇
临床医学   451篇
内科学   1603篇
皮肤病学   49篇
神经病学   438篇
特种医学   90篇
外科学   629篇
综合类   32篇
一般理论   1篇
预防医学   181篇
眼科学   68篇
药学   407篇
中国医学   4篇
肿瘤学   399篇
  2024年   3篇
  2023年   39篇
  2022年   242篇
  2021年   362篇
  2020年   83篇
  2019年   120篇
  2018年   147篇
  2017年   110篇
  2016年   128篇
  2015年   163篇
  2014年   209篇
  2013年   284篇
  2012年   405篇
  2011年   419篇
  2010年   205篇
  2009年   142篇
  2008年   346篇
  2007年   378篇
  2006年   328篇
  2005年   308篇
  2004年   330篇
  2003年   304篇
  2002年   217篇
  2001年   19篇
  2000年   20篇
  1999年   24篇
  1998年   25篇
  1997年   14篇
  1996年   9篇
  1995年   12篇
  1994年   13篇
  1993年   8篇
  1992年   13篇
  1991年   6篇
  1990年   10篇
  1989年   8篇
  1988年   7篇
  1987年   4篇
  1986年   17篇
  1985年   6篇
  1984年   3篇
  1983年   3篇
  1982年   5篇
  1981年   8篇
  1980年   5篇
  1978年   4篇
  1977年   3篇
  1976年   5篇
  1975年   3篇
  1966年   3篇
排序方式: 共有5540条查询结果,搜索用时 15 毫秒
51.
A diagnostic procedure in the medical treatment of middle hydrothorax at haemodynamically efficient fetus has been presented in the research. Container of the liquid in the fetal thorax has been observed since the eleventh week of pregnancy. Infection by TORCH viruses has been excluded and typical 46,XX female karyotype has been found in the cytogenic test. A liquid in the pericardial sack (without any sings of the fetal heart defect) was observed in the ECHO examination from 23 to 37 week of pregnancy. Cesarean section was made after 37 weeks of pregnancy and the new-born baby was found to be in good condition, with body mass of 3130g and 9 points in the Apgar scale. The child cardiologist did not diagnose any heart disorders. Awaiting attitude, while monitoring the state of the fetus, seems to be the right course of action in cases of haemodynamically efficient fetus with isolated hydrothorax.  相似文献   
52.
OBJECTIVE: Well-known natural unspecific antimicrobial factors acting in the vagina are additionally reinforced during menstrual bleeding by hemocidins--a recently discovered novel class of microbicidal peptides generated proteolytically from hemoglobin. The aim of the presented research was to investigate the relation between the average length of menstrual bleeding and the frequency of urogenital infections. We expected that the shorter menstrual bleeding might increase the risk of urogenital infections because is synonymous with the shorter period of exposition on bactericidal action of hemocidins. STUDY DESIGN: The study contains statistical analysis of an average declared length of menstrual bleeding in the group of 267 young, sexually active women with the symptoms of urogenital infections. The control group consisted of 300 young healthy women. RESULTS: The length of menstrual bleeding in the group of patients with urogenital infections (average 4.35 days) was statistically significantly shorter than in the control group (average 4.95 days). The average length of the menstrual cycle was equal and counted ca. 28 days in both groups. CONCLUSION: The length of menstrual bleeding seems to be a significant factor in the vaginal ecology maintenance.  相似文献   
53.
OBJECTIVE: The purpose of the research was to provide a review of the efficacy of the TVT-O technique for the surgical treatment of stress urinary incontinence (SUI) and to assess surgical and postsurgical complications related to this technique. STUDY DESIGN: An initial assessment was carried out on 44 women who underwent TVT-O surgery between 16 September 2004 and 1 February 2005. The follow-ups after 3 and 12 months were attended by 37 and 35 patients, respectively. All 44 patients were included for the statistical estimation of intra- and postoperative complications, whereas improvement in the quality of life was assessed only in those patients who came for a follow-up visit. To assess the efficacy of the treatment, the participants were surveyed using the King questionnaire on the day preceding surgery and during a follow-up visit 3 and 12 months after surgery. The participants whose scores from the two questionnaires changed > or =90% were deemed to be cured. A considerable improvement in quality of life was recorded when the score was 89-75%. With scores of 74-50%, there was a reduction in SI symptoms. However, when the score was 50-0%, no improvement in quality of life was reported, and in participants with scores <0% the quality of life deteriorated. Statistical analysis was carried out using the Statistical Package for Social Sciences (SPSS) V. 10.0, with the Spearman correlation and Chi-squared tests. The results were considered statistically significant when P<0.05. RESULTS: After 12 months, total cure was achieved in 15 participants (42.8%), significant improvement was noted in 6 (17.1%), SUI symptoms abated in 4 (11.4%), no improvement was noted in 7 (20%), and quality of life deteriorated in 3 (8.7%). CONCLUSION: TVT-O surgery is an efficient and reasonably safe method of SUI treatment in women. The ease of use, short duration of surgery and hospitalisation, minor postsurgical discomfort and a small proportion of complications make this method acceptable to patients. With regard to the results of treatment, additional patients should be analysed for a longer period of time.  相似文献   
54.
Recovery of zinc and manganese from scrapped alkaline batteries were carried out in the following way: leaching in H2SO4 and selective precipitation of zinc and manganese by alkalization/neutralization. As a result of non-selective leaching, 95.6–99.7% Zn was leached and 83.7–99.3% Mn was leached. A critical technological parameter is the liquid/solid treatment (l/s) ratio, which should be at least 20 mL∙g−1. Selective leaching, which allows the leaching of zinc only, takes place with a leaching yield of 84.8–98.5% Zn, with minimal manganese co-leaching, 0.7–12.3%. The optimal H2SO4 concentration is 0.25 mol∙L−1. Precipitation of zinc and manganese from the solution after non-selective leaching, with the use of NaOH at pH = 13, and then with H2SO4 to pH = 9, turned out to be ineffective: the manganese concentrate contained 19.9 wt.% Zn and zinc concentrate, and 21.46 wt.% Mn. Better selectivity results were obtained if zinc was precipitated from the solution after selective leaching: at pH = 6.5, 90% of Zn precipitated, and only 2% manganese. Moreover, the obtained concentrate contained over 90% of ZnO. The precipitation of zinc with sodium phosphate and sodium carbonate is non-selective, despite its relatively high efficiency: up to 93.70% of Zn and 4.48–93.18% of Mn and up to 95.22% of Zn and 19.55–99.71% Mn, respectively for Na3PO4 and Na2CO3. Recovered zinc and manganese compounds could have commercial values with suitable refining processes.  相似文献   
55.
Recently, we have demonstrated a decreased level of iso-branched-chain fatty acids (iso-BCFAs) in patients with excessive weight. However, it is still unclear whether BCFAs may influence lipid metabolism and inflammation in lipogenic tissues. To verify this, human visceral adipocytes were cultured with three different concentrations of selected iso-BCFA (14-methylpentadecanoic acid) and anteiso-BCFA (12-methyltetradecanoic acid), and then the expression of genes associated with lipid metabolism (FASN—fatty acid synthase; SREBP1—sterol regulatory element-binding protein 1; SCD1—stearoyl-CoA desaturase; ELOVL4—fatty acid elongase 4; ELOVL6—fatty acid elongase 6; FADS2—fatty acid desaturase 2; FADS1–fatty acid desaturase 1) and inflammation (COX-2—cyclooxygenase 2; ALOX-15—lipoxygenase 15; IL-6—interleukin 6) were determined. This study demonstrates for the first time that incubation with iso-BCFA decreases the expression of adipocyte genes that are associated with lipid metabolism (except FASN) and inflammation. These findings suggest that changes in the iso-BCFA profile in obese patients may contribute to adipose inflammation and dyslipidemia. Further studies should evaluate whether iso-BCFA supplementation in obese patients would be beneficial.  相似文献   
56.
Wound healing and skin tissue regeneration remain the most critical challenges faced by medical professionals. Titanium(IV) oxide-based materials were proposed as components of pharmaceutical formulations for the treatment of difficult-to-heal wounds and unsightly scarring. A gallic acid-functionalized TiO2 nanomaterial (TiO2-GA) was obtained using the self-assembly technique and characterized using the following methods: scanning electron microscopy (SEM), transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), X-ray powder diffraction (XRPD), infrared spectroscopy (IR), Raman spectroscopy and thermogravimetry (TG). Additionally, physicochemical and biological tests (DPPH assay, Microtox® acute toxicity test, MTT assay) were performed to assess antioxidant properties as well as to determine the cytotoxicity of the novel material against eukaryotic (MRC-5 pd19 fibroblasts) and prokaryotic (Staphylococcus aureus, Escherichia coli, Candida albicans, Aliivibrio fischeri) cells. To determine the photocytotoxicity of the material, specific tests were carried out with and without exposure to visible light lamps (425 nm). Following the results, the TiO2-GA material could be considered an additive to dressings and rinsing suspensions for the treatment of difficult-to-heal wounds that are at risk of bacterial infections.  相似文献   
57.
Iron is an essential nutrient for a child’s proper development at every growth stage. It is crucial for the production of red blood and muscle cells, DNA replication, and the development of the brain, nervous and immune systems. Iron deficiency is the most common micronutrient deficiency in children worldwide. Despite widespread access to nutritional information for children, parents continue to make many feeding mistakes. This study aimed to assess whether any nutritional intervention would affect the iron status in children. The parents of 203 children were randomly assigned to one of two groups: the study group received intensive mobile nutritional education for a year, while the control group received no intervention. Blood tests were performed on both groups at the beginning of the study and one year later. The educational intervention resulted in statistically significantly higher levels of RBC (red blood cells; p = 0.020), HGB (haemoglobin; p = 0.039), HCT (haematocrit; p = 0.036), MCV (mean cell volume; p = 0.018) parameters and iron dietary intake (p ≤ 0.001). Even a non-targeted dietary intervention improves the iron status in children. As iron management is insufficient in most children, an iron-targeted nutritional intervention appears necessary.  相似文献   
58.
The article presents research on the potential use of organometallic compounds with the addition of antimony (III) oxide Sb2O3 as a coating additive that will make coatings susceptible to electroless metallization after prior surface irradiation with 193 nm wavelength laser radiation and a different number of laser pulses. The surface modification and activation effects were assessed by optical-imagining as well as by scanning electron microscopy (SEM) with energy dispersive analysis (EDX). It was found that the presence of Sb2O3 in the coating made it possible to reduce the content of the copper complex, causing an intensive surface ablation, resulting in the formation of a conical structure with a higher content of metallic copper nuclei.  相似文献   
59.
IntroductionAngiopoietin-2 (Ang-2) is a novel marker of coronary artery disease (CAD) and diabetes (DM). The aim was to evaluate Ang-2 as a potential new biomarker of non-ST elevation myocardial infarction (NSTEMI) in patients with or without type 2 DM (T2DM).Material and methodsThis was a multi-center, prospective study that included 138 (males: 91/66%) consecutive patients hospitalized due to NSTEMI, T2DM, or different cardiac disorders. The subjects were divided into four study groups: group A: 28 patients with NSTEMI and T2DM; group B: 47 patients with NSTEMI without T2DM; group C: 31 patients with T2DM, without a history of CAD; group D: 32 patients as a control group. Patients with NSTEMI underwent urgent coronarography. Clinical characteristics including biomarkers (hs-CRP, hsTnT, NT-proBNP, VEGF, HbA1c), SYNTAX SCORE, type of intervention (PCI vs. CABG), and number of implanted stents were taken into account in the analysis.ResultsSerum Ang-2 concentrations were significantly higher in patients with NSTEMI (group A: 1769 pg/ml; group B: 1757 pg/ml) and patients with T2DM (group C: 1993 pg/ml) as compared to the patients without CAD and without T2DM (group D: 866.8 pg/ml; p < 0.05). The prognostic accuracy of Ang-2 in NSTEMI diagnosis was determined with the area under the ROC curve (area under curve (AUC) = 0.63).ConclusionsAngiopoietin-2 serum concentration is elevated in the presence of NSTEMI in patients with and without T2DM and does not correspond to the degree of myocardial injury and hemodynamic status. Ang-2 remains elevated also in patients with T2DM without a history of CAD.  相似文献   
60.
Within these studies, the effect of surface topography for hydrophobic coatings was studied both numerically and experimentally. Chemically modified polyurethane coating was patterned by application of a laser beam. A set of patterns with variously distant linear peaks and grooves was obtained. The cross section of the pattern showed that the edges of the peaks and grooves were not sharp, instead forming a rounded, rectangle-like shape. For such surfaces, experimental studies were performed, and in particular the static contact angle (SCA), contact angle hysteresis (CAH), and roll-off angle (ROA) were measured. Profilometry was used to create a numerical representation of the surface. Finite volume method was then applied to simulate the behavior of the water droplets. The model developed herewith enabled us to reproduce the experimental results with good accuracy. Based on the verified model, the calculation was extended to study the behavior of the water droplet on the simulated patterns, both spiked and rectangular. These two cases, despite a similar SCA of the water droplet, have shown extremely different ROA. Thus, more detailed studies were dedicated to other geometrical features of such topography, such as the size and distance of the surface elements. Based on the results obtained herewith, the future design of superhydrophobic and/or icephobic topography is discussed.  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