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   2099篇
  免费   114篇
  国内免费   12篇
耳鼻咽喉   10篇
儿科学   57篇
妇产科学   45篇
基础医学   228篇
口腔科学   32篇
临床医学   137篇
内科学   581篇
皮肤病学   77篇
神经病学   150篇
特种医学   75篇
外科学   314篇
综合类   49篇
一般理论   2篇
预防医学   212篇
眼科学   23篇
药学   130篇
中国医学   10篇
肿瘤学   93篇
  2023年   32篇
  2022年   51篇
  2021年   111篇
  2020年   59篇
  2019年   68篇
  2018年   103篇
  2017年   79篇
  2016年   73篇
  2015年   58篇
  2014年   67篇
  2013年   108篇
  2012年   150篇
  2011年   167篇
  2010年   92篇
  2009年   90篇
  2008年   105篇
  2007年   107篇
  2006年   94篇
  2005年   104篇
  2004年   84篇
  2003年   68篇
  2002年   59篇
  2001年   33篇
  2000年   29篇
  1999年   37篇
  1998年   10篇
  1997年   16篇
  1996年   6篇
  1995年   3篇
  1994年   6篇
  1993年   4篇
  1992年   10篇
  1991年   8篇
  1990年   12篇
  1989年   20篇
  1988年   13篇
  1987年   10篇
  1986年   12篇
  1985年   11篇
  1983年   3篇
  1982年   6篇
  1981年   5篇
  1979年   6篇
  1978年   4篇
  1977年   5篇
  1976年   3篇
  1975年   5篇
  1974年   4篇
  1973年   5篇
  1972年   2篇
排序方式: 共有2225条查询结果,搜索用时 15 毫秒
1.
Purpose: Traffic accidents are one of the major health problems in the world, being the first cause of burden of illness and the second leading cause of death in Iran. The Sistan-Baluchestan province is one of the most accidental provinces of Iran with the highest rate of accidents-caused deaths. This study was conducted to determine the risk factors associated with traffic accidents in Zahedan through 2013 to 2016. Methods: This analytical cross-sectional study was carried out on 223 drivers from Zahedan who were traumatized by traffic accident and sent to Zahedan hospitals. The data were obtained through interviews taken by the trained interviewers via refereeing to the medical records and collected in the researcher-made checklist. Census was obtained from the study subjects. For data analysis, independent t-test, one-way ANOVA, Chi-square and logistic regression were used with the Stata software version 11.0. Results: In this study, 223 male subjects with the mean age of (32.54 ± 12.95) years, 39.8% single and 60.2% married, entered for investigation. Most accidents (38.8%) occurred between 12:00 to 17:59. While driving, 47.1% of the study subjects were using cell phones, 89.1% had manual use of mobile phones, 21.9% had a habit of sending short message service (SMS) and 23.4% had sent SMS within 10 min before the accident. The one way analysis of variance showed that the mean age of individuals with marital status, driving experience, education and accident with motorcycle were significantly different (p < 0.05). Also, the multivariate logistic regression test indicated a significant relationship of smoking, ethnicity, insurance and SMS typing while driving with motorcycle accident (p < 0.05). Conclusion: In this study, SMS and smoking while driving had the highest risk among the variables studied in the motorcycle accidents. Therefore, effective education attempting to enhance people''s awareness about the consequences of using cell phone and smoking during driving to reduce traffic accidents seems necessary.  相似文献   
2.
Iron deficiency (ID) is one of the most commonly known forms of nutritional deficiencies. Low body iron is thought to induce neurologic defects but may also play a protective role against cancer development by cell growth arrest. Thus, ID may affect cellular pathways controlling cell growth and proliferation, the mechanism of which is still not fully understood. The serine/threonine protein kinase Akt and its downstream target, the mammalian Target of Rapamycin (mTOR), is known to play a crucial role in the regulation of cell growth and survival. Therefore, we hypothesized that Akt/mTOR pathway could be influenced by ID. Three-week-old male Wistar-strain rats were divided into 3 groups and the 2 groups had free access to a control diet (C group) or an iron-deficient diet (D group). The third group (PF group) were pair-fed the control diet to the mean intake of the D group. After 4 weeks, rats were killed and their brains were sampled. In separate experiments, COS-1 cells were cultured with or without the iron chelator deferoxamine. Western blots of brain samples and COS-1 lysates were used to analyze the expression and phosphorylation state of Akt, TSC2, mTOR, and S6 kinase proteins implicated in the Akt/mTOR pathway. Using 2 different ID models, we show for the first time that iron deficiency depresses Akt activity in rats and in COS-1 cells, leading to a decrease in mTOR activity.  相似文献   
3.
Recurrence of hepatitis C (HCV) following liver transplantation is common. Herpesvirus reactivation following transplant may have an immunomodulatory effect resulting in increased HCV replication. We studied whether cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6) may be associated with HCV recurrence and viral load after transplant. We prospectively followed 66 HCV liver-transplant recipients with serial viral load testing for CMV and HHV-6. Infection and viral load were correlated with the development of biopsy-proven HCV recurrence and HCV viral loads. Histologic recurrence of HCV occurred in 41/66 (62.1%) patients. In the primary analysis, CMV infection and disease, and HHV-6 infection were not associated with HCV recurrence. Peak CMV and HHV-6 viral loads were not significantly different in patients with and without recurrence. No correlation was observed between HCV viral loads at 1 and 3 months post-transplant and peak HHV-6 or CMV viral loads. In a subgroup analysis, HHV-6 infection was associated with the development of more severe recurrence (hepatitis and/or fibrosis score > or = 2) (p = 0.01). Also, fibrosis scores at last follow up were higher in patients with CMV disease (1.67 vs. 0.56; p = 0.016) and in patients with HHV-6 infection (1.18 vs. 0.55; p = 0.031). In conclusion, HHV-6 and CMV infection and viral load were not associated with increased overall rates of HCV recurrence or HCV viral load after liver transplantation but may be associated with more severe forms of recurrence.  相似文献   
4.
BACKGROUND/AIMS: It has recently been proposed that the refractive index (RI) measured by means of optical coherence tomography (OCT) may be a valid measure for hydration of skin. In this pilot study, using OCT in vivo, we aimed to investigate the interday variability of RI measurements and acute changes of RI following the application of a moisturizer. METHODS: Twenty healthy Caucasian volunteers were investigated on their forearms using a commercially available OCT system (SkinDex 300, ISIS optronics GmbH, Mannheim, Germany) fitted with an integrated algorithm for the evaluation of the RI. The interday repeatability of the OCT method was determined performing symmetrical measurements on both forearms on day 1, 5, 9, and 13. In order to investigate the acute effect of a moisturizer on RI, OCT assessments were performed before and 10 min after the application of an aqueous lotion with a lipophilic phase. As a control, the contralateral site was investigated in the same way, except for the use of distilled water instead of the lotion. RESULTS: Assessments of interday variability revealed insignificant (P>0.05) variances between the four measurement times as expressed in very small repeatability coefficients (right arm: 0.039; left arm 0.053) and small coefficients of variance (right arm: 1.02%; left arm: 1.38%). With regard to the RIs measured over time, we could not observe significant (P>0.05) differences between the two symmetrical anatomic sites (mean+/-SD of RI: 1.3893+/-0.0142 (right arm); 1.3875+/-0.0192 (left arm)). The acute effect of the moisturizer was indicated by a significant decrease of the RI 5 min after the application of the lotion (1.399+/-0.01 vs. 1.387+/-0.02; difference between means: 0.012; P=0.033; 95% confidence interval: 0.001-0.0023). However the control site treated with distilled water did not show significant differences between the two measurement times (1.387+/-0.013 vs. 1.391+/-0.023; difference between means: -0.004; P=0.57; 95% confidence interval: -0.019-0.011). CONCLUSIONS: In this pilot study, we have demonstrated that RI evaluation via OCT is a promising technique that may be used for the assessment of skin hydration in vivo. However, the direct comparison of OCT with standard methods, ideally such as nuclear magnetic resonance spectroscopy, is necessary.  相似文献   
5.
6.
BACKGROUND--It is possible that many deaths from pneumonia may involve the generation of inflammatory mediators and tissue damage by activated phagocytes. To test this hypothesis phagocyte function, plasma levels of interleukin 6 (IL-6), tumour necrosis factor alpha (TNF alpha), and soluble interleukin 2 receptor (IL-2R), disease severity, and outcome have been examined in 46 patients with community acquired pneumonia. METHODS--Polymorphonuclear leucocyte (PMNL) and monocyte function were measured daily by chemiluminescence in these patients during the first week of admission, and cytokine levels were subsequently determined by ELISA. A series of 61 healthy individuals were used as a control group for the chemiluminescence results. RESULTS--There was evidence of phagocyte, particularly PMNL, activation on admission in 76% of the patients. Most patients (86%) also had raised IL-2R levels on admission. IL-6 and unbound TNF alpha were present in 23% and 41% of patients at varying times during the course of the disease. There was little correlation between measurements of cytokine or phagocyte levels and outcome or indicators of disease severity, although this may be because of the small number of patients included in this preliminary study. CONCLUSIONS--These results are consistent with the hypothesis that activated phagocyte function and raised levels of circulating cytokines may contribute to the pathogenesis of community acquired pneumonia. There are striking similarities in this respect between pneumonia, adult respiratory distress syndrome, and sepsis.  相似文献   
7.
8.

Background

We conducted a monocentric retrospective study of patients with myelodysplastic syndromes (MDS) and autoimmune or inflammatory disorders (AIMs) and a literature review. We analyzed the association with subgroups of the WHO 2016 MDS classification and patient's survival in a case control study. Risk factors associated with survival were analyzed by uni- and multivariate analysis.

Results

From all MDS patients 11% presented with AIMs. These were heterogeneous and the most frequent where polyarthritis (25%) and autoimmune cytopenias (17%). No difference for frequency and type of AIMs was observed for the WHO 2016 MDS subgroups (p?=?.3). In the case control study WHO classification, karyotype abnormalities, IPSS-R and IPSS were similar in both groups. The overall survival from MDS diagnosis was better in the group with AIMs [10.3?±?0.6 (IC95% 6.2–12.9) versus 4.8?±?1.1?years (IC95% 4.2–8.7), p?=?.04]. The better survival was restricted to MDS with low or intermediate-1 IPSS [11.1?±?1.5 (IC95% 9.9-NR) versus 8.7?±?1.3?years (IC95% 4.8–10.3), p?=?.006]. The better survival was only observed when AIMs diagnosis was timely associated or appeared after MDS diagnosis (p?=?.04). Factors associated with a better overall survival and survival without AML were steroid dependence [respectively HR?=?0.042, p?=?.003, (IC95% 0.005–0.33) and HR?=?0.07, p?=?.002, (IC95% 0.013–0.39)], a diagnosis of AIMs and MDS timely associated [respectively HR?=?0.05, p?=?.009, (IC95% 0.006–0.478) and HR?=?0.1, p?=?.008, (IC95% 0.018–0.54)] or a diagnosis of AIMs after MDS [respectively HR?=?0.024, p?=?.009, (IC95% 0.001–0.39) and HR?=?0.04, p?=?.008, (IC95% 0.003–0.43)].

Conclusion

Autoimmune and inflammatory diseases associated to MDS are heterogeneous. AIMs diagnosed after or concomitantly to MDS seems associated with a better survival. Prospective studies are necessary to demonstrate that autoimmunity is associated to a better control of the MDS clone.  相似文献   
9.
Noninvasive imaging techniques might be of particular diagnostic value for studying and monitoring cutaneous inflammatory conditions such as contact dermatitis. We evaluate acute allergic contact dermatitis (AACD) by means of optical coherence tomography (OCT) and correlate the clinical grading of patch test reactions with the findings obtained from OCT. Twenty positive patch test reactions (+, n = 6; ++, n = 7; +++, n = 7) are investigated using a conventional OCT scanner. In comparison to the control sites, OCT of AACD showed pronounced skin folds, thickened and/or disrupted entrance signals, and a significant increase in epidermal thickness. Moreover, clearly demarcated signal-free cavities within the epidermis and considerable reduction of dermal reflectivity are demonstrated by OCT. Notably, the latter findings strongly correlate with the clinical patch test grading. OCT may be a useful tool for visualization of micromorphological features of AACD. However, before OCT can be employed as an objective parameter in grading severity of patch test reactions, larger studies are required that correlate clinical patch test readings and OCT findings with histopathology.  相似文献   
10.
BACKGROUND: Allergic rhinitis (AR) is the most common allergic problem in Kuwait. Most of the patients who have either AR or asthma are referred to the Al-Rashed Allergy Center. OBJECTIVE: To determine if there is a seasonal variation in AR in Kuwait and to correlate it with the daily pollen count. METHODS: Information about the new patients referred to the center over a 5-year study period (1996-2000) was extracted from the center's records. The daily pollen count in Kuwait city was obtained from the Air Biology Laboratory. RESULTS: There was a significant seasonal variation with a bimodal increase in the number of patients with AR referred to the center. The main peak in the number of patients occurred in September-October, and there was a smaller peak in April-May. The mean number +/- SD of new patients per month over the 5-year period varied from 87 +/- 32 for December to 367 +/- 104 for September. Similarly, the average daily pollen count varied from 3.7 +/- 1.0 pollens per mm3 in January to 124 +/- 92 in October. There was high correlation between the number of new AR patients and the average total pollen count (Pearson correlation, r=0.77, p<0.001), as well as with Chenopodiaceae and Amaranthaceae (weed) pollens (r=0.75, p<0.001), while there was no correlation between the number of new patients and either tree or grass pollens. CONCLUSION: Seasonal AR occurs during two periods in Kuwait, i.e. September-October and April-May, with September-October being the main season. The rise in AR during late summer in Kuwait is mainly associated with the pollination of Chenopodiaceae species.  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