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   8621篇
  免费   628篇
  国内免费   23篇
耳鼻咽喉   42篇
儿科学   251篇
妇产科学   247篇
基础医学   1314篇
口腔科学   181篇
临床医学   1011篇
内科学   1655篇
皮肤病学   240篇
神经病学   1150篇
特种医学   217篇
外科学   697篇
综合类   67篇
一般理论   9篇
预防医学   787篇
眼科学   300篇
药学   529篇
中国医学   20篇
肿瘤学   555篇
  2023年   74篇
  2022年   97篇
  2021年   205篇
  2020年   185篇
  2019年   215篇
  2018年   271篇
  2017年   212篇
  2016年   222篇
  2015年   270篇
  2014年   300篇
  2013年   456篇
  2012年   733篇
  2011年   717篇
  2010年   374篇
  2009年   339篇
  2008年   641篇
  2007年   590篇
  2006年   548篇
  2005年   518篇
  2004年   480篇
  2003年   446篇
  2002年   434篇
  2001年   63篇
  2000年   38篇
  1999年   60篇
  1998年   83篇
  1997年   72篇
  1996年   66篇
  1995年   45篇
  1994年   50篇
  1993年   41篇
  1992年   28篇
  1991年   22篇
  1990年   17篇
  1989年   15篇
  1988年   15篇
  1987年   19篇
  1986年   19篇
  1985年   17篇
  1984年   21篇
  1983年   16篇
  1982年   23篇
  1980年   16篇
  1978年   22篇
  1977年   14篇
  1976年   12篇
  1975年   12篇
  1971年   12篇
  1970年   10篇
  1968年   10篇
排序方式: 共有9272条查询结果,搜索用时 734 毫秒
161.
Background: Nonalcoholic fatty liver disease (NAFLD) is a common liver disease in obese children. Diets high in added fructose (high fructose corn syrup; HFCS) and glycemic index (GI)/glycemic load (GL) are associated with increased risk of NAFLD. Lifestyle modification is the main treatment, but no guidelines regarding specific dietary interventions for childhood NAFLD exist. We hypothesized that reductions in dietary fructose (total, free, and HFCS)/GI/GL over 6 months would result in improvements in body composition and markers of liver dysfunction and cardiometabolic risk in childhood NAFLD. Methods: Children and adolescents with NAFLD (n = 12) and healthy controls (n = 14) 7–18 years were studied at baseline and 3 and 6 months post–dietary intervention. Plasma markers of liver dysfunction (ALT, AST, γGT), cardiometabolic risk (TG, total cholesterol, LDL‐HDL cholesterol, Apo‐B100, Apo‐B48, Apo‐CIII, insulin, homeostasis model of assessment of insulin resistance [HOMA‐IR]), inflammation (TNF‐α, IL‐6, IL‐10), anthropometric, and blood pressure (BP) were studied using validated methodologies. Results: Significant reductions in systolic BP (SBP), percentage body fat (BF), and plasma concentrations of ALT (P = .04), Apo‐B100 (P < .001), and HOMA‐IR were observed in children with NAFLD at 3 and 6 months (P < .05). Dietary reductions in total/free fructose/HFCS and GL were related to reductions in SBP (P = .01), ALT (P = .004), HOMA‐IR (P = .03), and percentage BF in children with NAFLD. Reductions in dietary GI were associated with reduced plasma Apo‐B100 (P = .02) in both groups. With the exception of Apo‐B100, no changes in laboratory variables were observed in the control group. Conclusion: Modest reductions in fructose (total/free, HFCS) and GI/GL intake result in improvements of plasma markers of liver dysfunction and cardiometabolic risk in childhood NAFLD.  相似文献   
162.
Purpose: To describe experiences of shoulder pain after stroke, how pain affects daily life and perceived effects of interventions.

Method: A qualitative interview study including 13 community-dwelling persons (six women; median age 65?years) with persistent shoulder pain after stroke.

Results: Three categories emerged from the content analysis. In “Multiple pain characteristics” an insidious pain onset was reported. The pain existed both day and night and could be located around the shoulder girdle but also have radiation to the arm and hand. An explanation of the pain was seldom given. In “Limitations caused by the pain” it was described how the pain negatively influenced personal care, household activities and leisure, but also could lead to emotional reactions. In “Multiple pain interventions with various effects” a variety of interventions were described. Self-management interventions with gentle movements were perceived most effective. A restraint attitude to pain medication due to side effects was reported.

Conclusions: Shoulder pain after stroke can lead to a variety of pain characteristics. As the pain is complex and may affect many important areas in a person’s life, multidisciplinary rehabilitation interventions are important.

  • Implications for rehabilitation
  • Shoulder pain after stroke can lead to a variety of pain characteristics with radiation to the arm and hand

  • Shoulder pain often influence personal care, household activities and leisure negatively, which may lead to emotional reactions

  • Self-management interventions with gentle movements are perceived most effective

  • As the shoulder pain after stroke is complex, interventions by a multidisciplinary team may be needed

  相似文献   
163.
Objective: This study examined the prevalence of injecting‐related injuries and diseases (IRIDs) and associated risk factors among people who inject drugs (PWID) attending a primary health care facility in Sydney's Kings Cross. Methods: We calculated prevalence of a wide range of IRIDs utilising data reported by 702 PWID who completed a clinician‐administered survey at their first visit. Multivariable logistic regressions identified factors independently associated with at least one episode of: i) cutaneous and ii) non‐cutaneous IRIDs. Results: Lifetime prevalence of cutaneous IRIDs was 23%. Forty‐two per cent of PWID with a history of abscess attended hospital at their most recent episode. Female gender, lifetime receptive syringe sharing (RSS), injecting while in custody, and ever injecting in places other than the arm were independently associated with reporting at least one episode of cutaneous IRIDs. Ever injecting in sites other than the arm, injecting for five or more years and lifetime history of RSS were independently associated with at least one episode of non‐cutaneous IRIDs. Conclusions: IRIDs are a substantial health issue for PWID. Their ongoing surveillance is warranted particularly in primary care settings targeting PWID to inform prevention and early management, thus reducing complications that may require hospital admission.  相似文献   
164.

Purpose

To further characterise the performance of the diet history method and the 24-h recalls method, both in an updated version, a comparison was conducted.

Methods

The National Nutrition Survey II, representative for Germany, assessed food consumption with both methods. The comparison was conducted in a sample of 9,968 participants aged 14–80. Besides calculating mean differences, statistical agreement measurements encompass Spearman and intraclass correlation coefficients, ranking participants in quartiles and the Bland–Altman method.

Results

Mean consumption of 12 out of 18 food groups was higher assessed with the diet history method. Three of these 12 food groups had a medium to large effect size (e.g. raw vegetables) and seven showed at least a small strength while there was basically no difference for coffee/tea or ice cream. Intraclass correlations were strong only for beverages (>0.50) and revealed the least correlation for vegetables (<0.20). Quartile classification of participants exhibited more than two-thirds being ranked in the same or adjacent quartile assessed by both methods. For every food group, Bland–Altman plots showed that the agreement of both methods weakened with increasing consumption.

Conclusions

The cognitive effort essential for the diet history method to remember consumption of the past 4 weeks may be a source of inaccurateness, especially for inhomogeneous food groups. Additionally, social desirability gains significance. There is no assessment method without errors and attention to specific food groups is a critical issue with every method. Altogether, the 24-h recalls method applied in the presented study, offers advantages approximating food consumption as compared to the diet history method.
  相似文献   
165.
166.
167.
Trichosporon beigelii is a non‐pathogenic fungus that can however become an opportunist agent of disseminating and potentially fatal infections, especially in immunocompromised patients. In the literature, there are only 11 published cases of infective endocarditis due to T. beigelii. Most of these cases involved immunocompetent individuals and the main risk factor was the presence of a prosthetic valve. The longest interval between surgery and endocarditis was eight years. In the present study, a case of prosthetic valve endocarditis due to T. beigelii is reported in an immunocompetent patient 11 years after mitral valve replacement. As with similar cases, low clinical suspicion and negative blood cultures delayed the beginning of antifungal therapy and cardiac surgery. Considering the high mortality and severity of T. beigelii endocarditis, it should be considered when there is a prosthetic valve infection with negative blood cultures, irrespective of the time elapsed since the previous surgery.  相似文献   
168.

Chronic kidney disease (CKD) has been typically implicated in cardiovascular risk, considering the function the kidney has related to blood pressure, vitamin D, red blood cell metabolism, and electrolyte and acid-base regulation. However, neurological consequences are also attributed to this disease. Among these, recent large epidemiological studies have demonstrated an increased risk for Parkinson’s disease (PD) in patients with CKD. Multiple studies have evaluated individually the association of blood pressure, vitamin D, and red blood cell dysmetabolism with PD, however, no study has reviewed the potential mechanisms related to these components in context of CKD and PD. In this review, we explored the association of CKD and PD and linked the components of the former to propose potential pathways explaining a future increased risk for PD, where renin-angiotensin system, oxidative stress, and inflammation have a main role. Potential preventive and therapeutic interventions based on these associations are also explored. More preclinical studies are needed to confirm the potential link of CKD conditions and future PD risk, whereas more interventional studies targeting this association are warranted to confirm their potential benefit in PD.

  相似文献   
169.

Fluoxetine is the foremost prescribed antidepressant. Drugs acting on monoaminergic system may also regulate glutamatergic system. Indeed, the investigation of proteins associated with this system, such as Narp (neuronal activity-dependent pentraxin) and GluA4 subunit of AMPA receptor may reveal poorly explored modulations triggered by conventional antidepressants. This study aimed to uncover neurochemical mechanisms underlying the chronic fluoxetine treatment, mainly by evaluating these protein targets in the prefrontal cortex and in the hippocampus. Mice received a daily administration of fluoxetine (0.1, 1 or 10 mg/kg, p.o.) or potable water (vehicle group) for 21 days. These animals were submitted to the forced swim test (FST) to verify antidepressant-like responses and the open-field test (OFT) to assess locomotor activity. Modulation of signaling proteins was analyzed by western blot. Chronic treatment with fluoxetine (1 and 10 mg/kg) was effective, since it reduced the immobility time in the FST, without altering locomotor activity. Fluoxetine 10 mg/kg increased CREB phosphorylation and BDNF expression in the prefrontal cortex and hippocampus. Noteworthy, in the hippocampus fluoxetine also promoted Akt activation and augmented Narp expression. In the prefrontal cortex, a significant decrease in the expression of the GluA4 subunit and Narp were observed following fluoxetine administration (10 mg/kg). The results provide evidence of novel molecular targets potentially involved in the antidepressant effects of fluoxetine, since in mature rodents Narp and GluA4 are mainly expressed in the GABAergic parvalbumin-positive (PV+) interneurons. This may bring new insights into the molecular elements involved in the mechanisms underlying the antidepressant effects of fluoxetine.

  相似文献   
170.
BACKGROUND AND AIMS: To gain insight in intestinal epithelial proliferation, cell death, and gene expression during experimental colitis rats were treated with dextran sulfate sodium (DSS) for 7 days. MATERIALS AND METHODS: Proximal and distal colonic segments were excised on days 2, 5, 7, and 28. Epithelial proliferation, cell death, enterocyte gene expression (carbonic anhydrase I (CA I) and goblet cell gene expression (mucin, MUC2; trefoil factor 3, TFF3) were studied immunohistochemically and biochemically. RESULTS: Proliferative activity was decreased in the proximal and distal colon at the onset of disease (day 2). However, during active disease (days 5-7) epithelial proliferation was increased in the entire proximal colon and in the proximity of ulcerations in the distal colon. During DSS treatment the number of apoptotic cells in the epithelium of both colonic segments was increased. In the entire colon surface enterocytes became flattened and CA I negative during active disease (day 5-7). Additionally, CA I levels in the distal colon significantly decreased during this phase. In contrast, during the regenerative phase (day 28) CA I levels were restored in the distal colon and up-regulated in the proximal colon. During all disease phases increased numbers of goblet cells were observed in the surface epithelium of the entire colon. In the distal colon TFF3 expression extended to the bottom of the crypts during active disease. Finally, MUC2 and TFF3 expression was increased in the proximal colon during disease. CONCLUSION: DSS affected the epithelium by inhibiting proliferation and inducing apoptosis. DSS-induced inhibition of CA I expression indicates down-regulation of specific enterocyte functions. Accumulation of goblet cells in the surface epithelium and up-regulation of MUC2 and TFF3 expression in the proximal colon underline the importance of goblet cells in epithelial protection and repair, respectively.  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