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   2378篇
  免费   71篇
  国内免费   13篇
耳鼻咽喉   14篇
儿科学   83篇
妇产科学   9篇
基础医学   334篇
口腔科学   50篇
临床医学   126篇
内科学   647篇
皮肤病学   20篇
神经病学   200篇
特种医学   49篇
外科学   369篇
综合类   13篇
预防医学   27篇
眼科学   8篇
药学   202篇
中国医学   4篇
肿瘤学   307篇
  2023年   12篇
  2022年   22篇
  2021年   48篇
  2020年   13篇
  2019年   35篇
  2018年   26篇
  2017年   22篇
  2016年   34篇
  2015年   31篇
  2014年   54篇
  2013年   70篇
  2012年   102篇
  2011年   118篇
  2010年   77篇
  2009年   67篇
  2008年   143篇
  2007年   138篇
  2006年   134篇
  2005年   147篇
  2004年   157篇
  2003年   167篇
  2002年   169篇
  2001年   33篇
  2000年   20篇
  1999年   34篇
  1998年   58篇
  1997年   35篇
  1996年   41篇
  1995年   20篇
  1994年   58篇
  1993年   54篇
  1992年   34篇
  1991年   26篇
  1990年   25篇
  1989年   18篇
  1988年   21篇
  1987年   18篇
  1986年   19篇
  1985年   13篇
  1984年   12篇
  1983年   7篇
  1982年   19篇
  1981年   15篇
  1980年   19篇
  1979年   8篇
  1977年   8篇
  1976年   7篇
  1974年   6篇
  1958年   6篇
  1956年   6篇
排序方式: 共有2462条查询结果,搜索用时 171 毫秒
41.
The aim of the present study was to investigate the relationships between insulin resistance and soluble E-selectin, body mass index (BMI), leptin, and serum lipid profile including triglycerides in nonobese Japanese type 2 diabetic patients. A total of 97 nonobese Japanese type 2 diabetic patients aged 43 to 84 years were examined. The duration of diabetes was 11.2 +/- 0.8 years. In conjunction with BMI and fasting concentrations of plasma glucose, serum lipids (triglycerides, total cholesterol, and high-density lipoprotein cholesterol) and serum insulin, soluble E-selectin, and leptin were also measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula. Insulin resistance was estimated by the homeostasis model assessment. The subjects were divided into 2 groups according to the value of insulin resistance estimated by the homeostasis model assessment. Values greater than 2.5 were indicative of the insulin-resistant state, and values less than 2.5 were indicative of the insulin-sensitive state. The insulin-resistant group had significantly higher levels of E-selectin, leptin, triglycerides, total and LDL cholesterol, and diastolic blood pressure as compared with the insulin-sensitive group. There was, however, no significant difference in age, sex, diabetes duration, BMI, systolic blood pressure, HbA1c, and high-density lipoprotein cholesterol between the 2 groups. Univariate regression analysis showed that insulin resistance was positively correlated to E-selectin (r = 0.305, P = .003), BMI (r = 0.283, P = .006), leptin (r = 0.296, P = .004), HbA1c (r = 0.241, P = .018), serum triglycerides (r = 0.385, P < .001), serum total (r = 0.240, P = .019) and LDL cholesterol (r = 0.254, P = .013) levels, and systolic (r = 0.247, P = .024) and diastolic (r = 0.305, P = .006) blood pressure. Multiple regression analyses showed that insulin resistance was independently predicted by serum E-selectin (F = 18.4), serum leptin (F = 14.0) and serum triglycerides (F = 20.0) levels, which explained 45.0% of the variability of insulin resistance. From these results, it can be concluded that in conjunction with serum triglycerides and serum leptin, serum E-selectin is another important independent factor associated with insulin resistance in nonobese Japanese type 2 diabetic patients.  相似文献   
42.
BACKGROUND: Endoscopic submucosal dissection (ESD) of early gastric cancer is less invasive than surgical resection, and if technically feasible, it may result in less long-term morbidity than does incisional surgery. However, ESD is technically difficult in patients who have had a previous distal gastrectomy. OBJECTIVE: Our purpose was to retrospectively assess the results of ESD of early gastric cancer in the remnant stomach. DESIGN: Case series. SETTING AND PATIENTS: A total of 31 lesions in 30 patients with early remnant gastric cancer were treated with ESD at Okayama University Hospital, Tsuyama Central Hospital, Hiroshima City Hospital, Kagawa Prefectural Central Hospital, and Mitoyo General Hospital from March 2001 to January 2007. INTERVENTION: ESD. MAIN OUTCOME MEASUREMENTS: En bloc resection rate, complete resection rate, operation time, and complications. RESULTS: En bloc resection and complete resection were achieved in 30 (97%) and in 23 (74%) lesions, respectively. The median operation time required for ESD in the remnant stomach was 113 minutes (range 45-450 minutes). Perforation occurred in 4 (13%). The incidence of delayed bleeding requiring blood transfusion was 0%. LIMITATION: Short duration of follow-up. CONCLUSIONS: ESD is feasible in the remnant stomach but has a relatively high complication rate and should only be performed by experienced endoscopists.  相似文献   
43.
Substance P containing nerve fibers in rectal mucosa of ulcerative colitis   总被引:3,自引:0,他引:3  
BACKGROUND AND PURPOSE: The intestine is rich in peptidergic innervation, which modulates mucosal immune responses. Among neuropeptides, substance P (SubP) has received considerable attention for stimulatory effects on various immunocytes in inflammatory diseases. In our prior study, we demonstrated increased innervation of SubP containing nerve fibers (SubP fibers) in ulcerative colitis (UC) surgically resected colonic specimens. In the present study, we examined the alterations of SubP fibers among various subgroups of UC, divided according to clinicopathologic features. METHODS: Distribution of SubP fibers were examined immunohistochemically in the rectal biopsy specimens of UC. The UC group was further divided into subgroups according to six clinicopathologic parameters. The linear density of SubP fibers was measured by digitalized morphometry for quantitative analysis. RESULTS: Multivariate analysis revealed significant correlations between linear density of SubP fibers vs.activity of diseases and total dose of prednisolone. Linear density was significantly increased in active cases of UC (active UC, 22.6±1.6 μm/1,000 μm 2;vs.inactive UC, 12.2±0.8 μm/1,000 μm 2;P<0.01). Furthermore, the increase was pronounced in cases that showed persistent inflammation and, accordingly, needed a high dose or continuous administration of prednisolone. CONCLUSION: Alterations in SubP fibers appear to play an important role in the pathogenesis of UC.  相似文献   
44.
Introduction:Gastric varices can be present in up to 20% of patients with portal hypertension. However, a varix of the left gastroepiploic vein (LGV) is extremely rare. Surgery is required if bleeding occurs; thus, precise diagnosis is crucial. We present a successful case of preoperative diagnosis intraabdominal varix of the LGV using three-dimensional-computed tomography angiography (3D-CTA) followed by laparoscopic resection. This is the first report of a case with variant LGV. Our study demonstrates the efficacies of 3D-CTA and laparoscopic surgery for the diagnosis and safe resection of the intraabdominal varix, respectively.Patient concerns:A 74-year-old woman was referred to our department with a tumor in the abdominal cavity. On physical examination, no lumps were palpable in the upper abdomen.Diagnosis:The enhanced CT was revealed that the tumor was not enhanced in the early phase, but in the equilibrium phase. Moreover, 3D-CTA clearly revealed that the tumor was being supplied by the LGV. Thus, it was diagnosed as a variant of the LGV.Interventions:Surgical resection was performed laparoscopically as per the guidance of preoperative 3D-CTA findings. During surgery, a dark tumor was found along the gastroepiploic vessels, supplied by the LGV. The tumor was resected safely based on the preoperative information.Outcomes:Histopathological examination of the tumor showed accumulation of various vessels, but no malignant cells. Therefore, we made a final diagnosis of the tumor as an LGV varix. For follow-up, an annual CT examination was performed and after 3 years postoperation, no recurrence was observed.Conclusions:In the present case, we have achieved a successful preoperative diagnosis using 3D-CTA, and resection was safely accomplished using laparoscopy guided by preoperative anatomical information. This is the first report of an LGV variant. Appropriate management is crucial because bleeding is a catastrophic event. Therefore, imaging procedures such as 3D-CTA for diagnosis, followed by safe resection by laparoscopic surgery, are effective tools for the treatment of epiploic vein varices.  相似文献   
45.
Blood levels of inflammatory-related cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, are elevated in patients with alcoholic liver diseases. We investigated the effects of these cytokines and ethanol on the expression of hepatic asialoglycoprotein receptors (AGPRs) in a human hepatoblastoma cell line, HepG2. An [125I]-asialo-orosomucoid binding assay showed significant increases in surface AGPR numbers in HepG2 cells by treatment with IL-1β, IL-6, and TNF-α, to levels which were approximately 130% of the values in untreated control cells. However, the enhanced AGPR numbers induced by treatment with these cytokines were markedly suppressed, to 70%–80% of the number in the untreated cells, by treatment with ethanol. Immunological detection of AGPR with a specific antibody demonstrated that the modulation of surface AGPR numbers was correlated with the cellular expression levels of AGPR. These results suggest that, although IL-1β, IL-6, and TNF-α stimulate the synthesis of hepatic AGPR, ethanol suppresses the expression of AGPR augmented by these cytokines. This leads to an increase in serum asialo-orosomucoid levels caused by the disordered catabolism mediated by AGPR in patients with alcoholic liver disease. (Received Dec. 5, 1997; accepted May 22, 1998)  相似文献   
46.
Trait anxiety is a risk factor for the development and maintenance of affective disorders, and insights into the underlying brain mechanisms are vital for improving treatment and prevention strategies. Translational studies in non-human primates, where targeted neurochemical and genetic manipulations can be made, are critical in view of their close neuroanatomical similarity to humans in brain regions implicated in trait anxiety. Thus, we characterised the serotonergic and regional brain volume correlates of trait-like anxiety in the marmoset monkey. Low- and high-anxious animals were identified by behavioral responses to a human intruder (HI) that are known to be sensitive to anxiolytic drug treatment. Extracellular serotonin levels within the amygdala were measured with in vivo microdialysis, at baseline and in response to challenge with the selective serotonin reuptake inhibitor, citalopram. Regional brain volume was assessed by structural magnetic resonance imaging. Anxious individuals showed persistent, long-term fearful responses to both a HI and a model snake, alongside sustained attention (vigilance) to novel cues in a context associated with unpredictable threat. Neurally, high-anxious marmosets showed reduced amygdala serotonin levels, and smaller volumes in a closely connected prefrontal region, the dorsal anterior cingulate cortex. These findings highlight behavioral and neural similarities between trait-like anxiety in marmosets and humans, and set the stage for further investigation of the processes contributing to vulnerability and resilience to affective disorders.  相似文献   
47.
BACKGROUNDRecent improvements in the prognosis of patients with esophageal cancer have led to the increased occurrence of gastric tube cancer (GTC) in the reconstructed gastric tube. However, there are few reports on the treatment results of endoscopic submucosal dissection (ESD) for GTC.AIMTo evaluate the efficacy and safety of ESD for GTC after esophagectomy in a multicenter trial.METHODSWe retrospectively investigated 48 GTC lesions in 38 consecutive patients with GTC in the reconstructed gastric tube after esophagectomy who had undergone ESD between January 2005 and December 2019 at 8 institutions participating in the Okayama Gut Study group. The clinical indications of ESD for early gastric cancer were similarly applied for GTC after esophagectomy. ESD specimens were evaluated in 2-mm slices according to the Japanese Classification of Gastric Carcinoma with curability assessments divided into curative and non-curative resection based on the Gastric Cancer Treatment Guidelines. Patient characteristics, treatment results, clinical course, and treatment outcomes were analyzed.RESULTSThe median age of patients was 71.5 years (range, 57-84years), and there were 34 men and 4 women. The median observation period after ESD was 884 d (range, 8-4040 d). The median procedure time was 81 min (range, 29-334 min), the en bloc resection rate was 91.7% (44/48), and the curative resection rate was 79% (38/48). Complications during ESD were seen in 4% (2/48) of case, and those after ESD were seen in 10% (5/48) of case. The survival rate at 5 years was 59.5%. During the observation period after ESD, 10 patients died of other diseases. Although there were differences in the procedure time between institutions, a multivariate analysis showed that tumor size was the only factor associated with prolonged procedure time.CONCLUSIONESD for GTC after esophagectomy was shown to be safe and effective.  相似文献   
48.
49.
50.
OBJECTIVE: Transplantation of hematopoietic stem cells (HSCs) is usually accomplished through intravenous injection, a complex process that requires recognition of bone marrow vasculature and migration to a supportive microenvironment. Hence, some populations of HSCs, including cord blood (CB) Lin(-)CD34(-) stem cells, do not engraft well in bone marrow (BM) of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. In this study, we examined the effect of human stromal interactions on the properties of CB Lin(-)CD34(-) cells. MATERIALS AND METHODS: CD34 and CXCR4 expression on fresh CB Lin(-)CD34(-) cells and CB Lin(-)CD34(-) cells cocultured with human stromal cells were analyzed. Homing activity and engraftment of these cells were assessed using NOD/SCID mice. In an attempt to identify the stromal CXCR4-inducing factor, CB Lin(-)CD34(-) cells were cocultured with a noncontact culture system in the presence of several inhibitors. RESULT: Coculture with human stromal cells induced expression of CD34 and CXCR4 on CB Lin(-)CD34(-) cells. CXCR4 expression on CB Lin(-)CD34(-) cells was induced even in the noncontact culture condition, suggesting that this CXCR4-inducing factor is soluble. Moreover, CXCR4 induction was inhibited by the soluble Wnt inhibitor DKK1. Furthermore, these cells acquired homing activity and engrafted in the BM of NOD/SCID mice after intravenous injection. CONCLUSION: These findings may be useful for understanding the role of stromal cells in homing and engraftment of HSCs.  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