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   5614篇
  免费   266篇
  国内免费   58篇
耳鼻咽喉   63篇
儿科学   75篇
妇产科学   143篇
基础医学   431篇
口腔科学   172篇
临床医学   376篇
内科学   1427篇
皮肤病学   184篇
神经病学   519篇
特种医学   228篇
外科学   914篇
综合类   35篇
预防医学   325篇
眼科学   168篇
药学   264篇
中国医学   6篇
肿瘤学   608篇
  2024年   5篇
  2023年   38篇
  2022年   97篇
  2021年   142篇
  2020年   95篇
  2019年   107篇
  2018年   152篇
  2017年   104篇
  2016年   151篇
  2015年   162篇
  2014年   245篇
  2013年   302篇
  2012年   441篇
  2011年   513篇
  2010年   279篇
  2009年   264篇
  2008年   458篇
  2007年   457篇
  2006年   401篇
  2005年   391篇
  2004年   327篇
  2003年   284篇
  2002年   230篇
  2001年   36篇
  2000年   22篇
  1999年   39篇
  1998年   42篇
  1997年   28篇
  1996年   23篇
  1995年   11篇
  1994年   13篇
  1993年   3篇
  1992年   10篇
  1991年   4篇
  1990年   4篇
  1989年   2篇
  1988年   7篇
  1987年   4篇
  1985年   2篇
  1984年   4篇
  1982年   5篇
  1981年   4篇
  1980年   8篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   3篇
  1963年   1篇
排序方式: 共有5938条查询结果,搜索用时 0 毫秒
61.
62.
63.
Unipolar and bipolar depressive episodes have a similar clinical presentation that suggests common dysfunction of the brain’s reward system. Here, we evaluated the relationship of both dimensional depression severity and diagnostic category to reward system function in both bipolar and unipolar depression. In total, 89 adults were included, including 27 with bipolar depression, 25 with unipolar depression, and 37 healthy comparison subjects. Subjects completed both a monetary reward task and a resting-state acquisition during 3T BOLD fMRI. Across disorders, depression severity was significantly associated with reduced activation for wins compared with losses in bilateral ventral striatum, anterior cingulate cortex, posterior cingulate cortex, and right anterior insula. Resting-state connectivity within this reward network was also diminished in proportion to depression severity, most notably connectivity strength in the left ventral striatum. In addition, there were categorical differences between patient groups: resting-state connectivity at multiple reward network nodes was higher in bipolar than in unipolar depression. Reduced reward system task activation and resting-state connectivity therefore appear to be a brain phenotype that is dimensionally related to depression severity in both bipolar and unipolar depression. In contrast, categorical differences in reward system resting connectivity between unipolar and bipolar depression may reflect differential risk of mania. Reward system dysfunction thus represents a common brain mechanism with relevance that spans categories of psychiatric diagnosis.  相似文献   
64.
BackgroundIn Vitro Fertilization (IVF) is increasingly becoming a necessary mode of reproduction. This high risk group is prone to Gestational Diabetes Mellitus (GDM) which further exposes these pregnancies to an increased risk of adverse outcomes. In light of the limited data in the current literature, further investigation is needed regarding the time of GDM diagnosis in IVF pregnancies as well as the outcome of IVF pregnancies complicated by GDM.MethodsIn this three center pilot cross sectional study, the data of 101 singleton IVF pregnancies complicated by GDM were analyzed. Prompt GDM diagnosis in IVF pregnancies was accomplished by self-blood glucose monitoring (SMBG) from the first antenatal visit and confirmed by an OGTT. To evaluate pregnancy outcome, maternal and fetal complications in the 101 GDM IVF group was compared to 101 IVF as well as 101 spontaneous conceptions (SC). The three groups were matched by age. The effect of demographic and glycemic parameters on the outcome of GDM IVF pregnancies was investigated.ResultsGDM diagnosis was made before the 24th week in 37.6% of the GDM IVF group. The week of delivery was earlier for the GDM IVF group (37 ± 1.7) relative to the IVF (37.9 ± 0.9, p < 0.001) and the SC group (38.1 ± 0.8, p < 0.001). GDM IVF pregnancies exhibited greater preeclampsia rates and 84.8% underwent caesarian section. No significant difference regarding LGA and SGA birth weights was found. Complications of GDM IVF pregnancies were associated with the 1-h postprandial BG (r = 0.267, p = 0.007).ConclusionGDM screening in IVF pregnancies may be considered earlier than the 24th week. IVF pregnancies affected by GDM are prone to increased maternal and fetal complications which are associated with 1-h postprandial BG.  相似文献   
65.
BACKGROUND/AIMS: Primary and metastatic liver tumors are the most common malignancies that resist conventional chemotherapy and radiotherapy. Several immunotherapies have been attempted for cancer treatment on the basis of stimulating host immune response to tumors and recent development of combined targeting locoregional immunochemotherapy reported with promising results. However, the efficacy of this therapeutic modality is not yet widely established. METHODOLOGY: We reviewed the medical literature for publications dealing with the value of locoregional immunochemotherapy in patients with primary or metastatic liver tumors. RESULTS: We found that 5 and 7 studies have been controlled and inadequately controlled, respectively. Among 131 patients with primary liver cancer, 40 were treated with combined locoregional immunochemotherapy, and 20 with systemic immunochemotherapy, and 71 with systemic chemotherapy served as two control groups. Complete or partial response was observed in 32 out of 40 (80%) patients who received combined locoregional therapy, and in 10 out of 20 (50%) systemic immunochemotherapy controls (P = 0.03). Survival was three times higher in the patients who received combined locoregional therapy compared with systemic chemotherapy controls (18 vs. 5.6 months). Recurrence of tumor was higher in systemic immunochemotherapy controls (P = 0.003). Among 286 patients with metastatic liver disease, 180 patients were treated with combined locoregional immunochemotherapy and 106 patients with systemic immunochemotherapy. Response (complete or partial) was observed in 65 out of 98 (66.3%) patients who received combined therapy, and in 4 out of 26 (15.4%) controls (P < = 0.001). Survival was two-fold higher in the patients treated with combined therapy (21 vs. 10.5 months). Tumor recurrence was higher in the systemic immunochemotherapy controls (P < = 0.001). CONCLUSIONS: The observational studies indicate a plausible therapeutic rationale for the introduction of locoregional immunotherapy in patients with primary and metastatic liver disease.  相似文献   
66.
OBJECTIVE: Metabolic syndrome is a condition that promotes atherosclerosis and increases the risk of cardiovascular mortality and morbidity. We evaluated whether leisure time physical activity is associated with the levels of inflammatory and coagulation markers, in people with metabolic syndrome. METHODS: From May 2001 to December 2002 we randomly enrolled 1514 men and 1528 women (>18 years old), without any clinical evidence of cardiovascular disease, stratified by age-gender (census 2001). The population of the study was divided into those who fulfilled the NCEP ATP III criteria for the metabolic syndrome (n=701 or 33% men and 13% women) and the rest of the participants (n=2341). We assessed the relationship between self-reported physical activity status and inflammatory, and coagulation markers [i.e., C-reactive protein (CRP), serum amyloid-A (SAA), interleukin (IL)-6, tumour necrosis factor (TNF)-alpha, white blood cell (WBC) counts, and fibrinogen (FIB)], after taking into account the effect of several confounders. RESULTS: Of the non-metabolic syndrome group, 56% of men and 58% of women were classified as sedentary, while of the metabolic syndrome group 58% men and 72% women were sedentary. After controlling for various potential confounders we found that physically active individuals with the metabolic syndrome had 36% lower levels of CRP, 15% lower levels of WBC, 19% lower levels of SAA, 15% lower levels of TNF-alpha, 30% lower levels of IL-6 and 15% lower levels of FIB, compared to sedentary (all P<0.05). Similar results were observed in the non-metabolic syndrome group. CONCLUSIONS: The adoption of a physically active lifestyle is independently associated with lower levels of the investigated biomarkers in individuals with the metabolic syndrome. The latter may suggest a pathway for reducing cardiovascular events, even in high-risk people.  相似文献   
67.
Bone marrow angiogenesis has recently been implicated in the pathophysiology and course of various haematological malignancies. Little is known, however, about the significance of this phenomenon in hairy cell leukaemia (HCL). We evaluated various morphometric characteristics of microvessels, highlighted by means of anti-CD34 immunohistochemistry, in the bone marrow of 44 patients with typical HCL, before and after treatment with interferon-alpha (IFN-alpha). Overall, bone marrow from 103 HCL patients and 20 controls was examined. Microvessel density (MVD) and several size- and shape-related parameters were quantified in the region of most intense vascularization using image analysis. MVD, size-related parameters and the percentage of branching microvessels were higher in HCL than in controls. Likewise, perimeter counts were higher in partial/non-responders than in complete responders. Achievement of complete response was accompanied by smaller calibre microvessels. IFN-alpha induced a decrease in MVD and branching values in cases with diffuse marrow involvement. In univariate analysis, progression-free survival was adversely affected by MVD, branching and major axis length. Multivariate analysis indicated that MVD/branching independently affected progression-free survival and the likelihood of complete response. Our data suggest that the generation of bone marrow microvessels indicated an increased risk of progression and IFN-alpha treatment failure in HCL. Furthermore, the prognostic significance of angiogenesis requires the concomitant assessment of MVD and the complexity of the microvascular network.  相似文献   
68.
69.
OBJECTIVES: We sought to investigate the effects of physical training on circulating proinflammatory cytokines and the soluble apoptosis mediators Fas (sFas) and Fas ligand (sFasL) in patients with chronic heart failure (CHF). BACKGROUND: Recent investigations have shown an overexpression of circulating proinflammatory cytokines and soluble apoptosis mediators in patients with CHF, which may be related to their exercise intolerance and clinical deterioration. METHODS: Plasma levels of tumor necrosis factor-alpha (TNF-alpha), soluble TNF receptors I and II (sTNF-RI and sTNF-RII, respectively), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), sFas and sFasL were measured in 24 patients with stable CHF (New York Heart Association functional class II/III; left ventricular ejection fraction 23.2 +/- 1.3%) and in 20 normal control subjects before and after a 12-week program of physical training in a randomized, crossover design. Functional status of patients with CHF was evaluated by using a cardiorespiratory exercise test to measure peak oxygen consumption (VO2max). RESULTS: Physical training produced a significant reduction in plasma levels of TNF-alpha (7.5 +/- 1.0 pg/ml vs. 4.6 +/- 0.7 pg/ml, p < 0.001), sTNF-RI (3.3 +/- 0.2 ng/ml vs. 2.7 +/- 0.2 ng/ml, p < 0.005), sTNF-RII (2.6 +/- 0.2 ng/ml vs. 2.3 +/- 0.2 ng/ml, p = 0.06), IL-6 (8.3 +/- 1.2 pg/ml vs. 5.9 +/- 0.8 pg/ml, p < 0.005), sIL-6R (34.0 +/- 3.0 ng/ml vs. 29.2 +/- 3.0 ng/ml, p < 0.01), sFas (5.5 +/- 0.7 ng/ml vs. 4.5 +/- 0.8 ng/ml, p = 0.05) and sFasL (34.9 +/- 5.0 pg/ml vs. 25.2 +/- 4.0 pg/ml, p < 0.05), as well as a significant increase in VO2max (16.3 +/- 0.7 ml/kg per min vs. 18.7 +/- 0.8 ml/kg per min, p < 0.001). Good correlations were found between a training-induced increase in VO2max and a training-induced reduction in levels of the proinflammatory cytokine TNF-alpha (r = -0.54, p < 0.01) and the apoptosis inducer sFasL (r = -0.57, p < 0.005) in patients with CHF. In contrast, no significant difference in circulating cytokines and apoptotic markers was found with physical training in normal subjects. CONCLUSIONS: Physical training reduces plasma levels of proinflammatory cytokines and the sFas/sFasL system in patients with CHF. These immunomodulatory effects may be related to the training-induced improvement in functional status of patients with CHF.  相似文献   
70.
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