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   4435篇
  免费   194篇
  国内免费   61篇
耳鼻咽喉   16篇
儿科学   42篇
妇产科学   61篇
基础医学   582篇
口腔科学   46篇
临床医学   288篇
内科学   1408篇
皮肤病学   24篇
神经病学   299篇
特种医学   186篇
外科学   837篇
综合类   18篇
预防医学   123篇
眼科学   47篇
药学   283篇
中国医学   12篇
肿瘤学   418篇
  2023年   41篇
  2022年   65篇
  2021年   92篇
  2020年   46篇
  2019年   68篇
  2018年   72篇
  2017年   86篇
  2016年   82篇
  2015年   58篇
  2014年   101篇
  2013年   146篇
  2012年   224篇
  2011年   226篇
  2010年   121篇
  2009年   110篇
  2008年   241篇
  2007年   276篇
  2006年   248篇
  2005年   310篇
  2004年   307篇
  2003年   264篇
  2002年   291篇
  2001年   139篇
  2000年   114篇
  1999年   101篇
  1998年   59篇
  1997年   46篇
  1996年   41篇
  1995年   49篇
  1994年   27篇
  1993年   20篇
  1992年   80篇
  1991年   64篇
  1990年   58篇
  1989年   68篇
  1988年   37篇
  1987年   42篇
  1986年   29篇
  1985年   25篇
  1984年   27篇
  1983年   25篇
  1982年   12篇
  1980年   14篇
  1979年   18篇
  1978年   18篇
  1976年   10篇
  1974年   8篇
  1973年   8篇
  1972年   9篇
  1971年   11篇
排序方式: 共有4690条查询结果,搜索用时 15 毫秒
61.
62.
We treated 18 patients with chronic hepatitis C by recombinant interferon-α (6 MIU for 24 weeks). In seven patients, serum aminotransferase levels declined to normal (responders). To evaluate the effect of interferon on matrix metalloproteinases (MMPs) and their inhibitors, namely tissue inhibitors of metalloproteinases (TIMPs), the serum levels of these enzymes were determined by enzyme immunoassay (EIA) using a specific monoclonal antibody. In responders, there was a tendency, but not a significant one, towards either an increase in serum MMP 1 levels or a decrease in serum TIMP 1 levels. In contrast, in nonresponders, both a significant decrease in MMP 1 and MMP 3 and a significant increase in TIMP 1 were observed. The number of cases of either increase in serum MMP levels or decrease in serum TIMP levels was significantly larger in responders than in nonresponders. Furthermore, the ratio of MMP 1 to TIMP 1 significantly increased in responders, suggesting that the balance between matrix formation and degradation in hepatic fibrosis tended to move toward degradation. These data indicate that interferon may exert a beneficial effect on hepatic fibrosis in parallel with improvement of aminotransferase activity.  相似文献   
63.
64.
Purpose:To evaluate the feasibility for the detection of slight contrast effects after intravenous administration of single dose gadolinium-based contrast agent (IV-SD-GBCA), the time course of the GBCA distribution up to 24 h was examined in various fluid spaces and brain parenchyma using 3D-real IR imaging and MR fingerprinting (MRF).Methods:Twenty-four patients with a suspicion of endolymphatic hydrops were scanned at pre-administration and at 10 min, 4 and 24 h post-IV-SD-GBCA. 3D-real IR images and MRF at the level of the internal auditory canal were obtained. The signal intensity on the 3D-real IR image of the cerebrospinal fluid (CSF) in the cerebellopontine angle cistern (CPA), Sylvian fissure (Syl), lateral ventricle (LV), and cochlear perilymph (CPL) was measured. The T1 and T2 values of cerebellar gray (GM) and white matter (WM) were measured using MRF. Each averaged value at the various time points was compared using an analysis of variance.Results:The signal intensity on the 3D-real IR image in each CSF region peaked at 4 h, and was decreased significantly by 24 h (P < 0.05). All patients had a maximum signal intensity at 4 h in the CPA, and Syl. The mean CPL signal intensity peaked at 4 h and decreased significantly by 24 h (P < 0.05). All patients but two had a maximum signal intensity at 4 h. Regarding the T1 value in the cerebellar WM and GM, the T1 value at 10 min post-IV-GBCA was significantly decreased compared to the pre-contrast scan, but no significant difference was observed at the other time points. There was no significant change in T2 in the gray or white matter at any of the time points.Conclusion:Time course of GBCA after IV-SD-GBCA could be evaluated by 3D-real IR imaging in CSF spaces and in the brain by MRF.  相似文献   
65.
Complex regional pain syndrome (CRPS) is a chronic pain disorder with a clear acute-to-chronic transition. Preclinical studies demonstrate that toll-like receptor 4 (TLR4), expressed by myeloid-lineage cells, astrocytes, and neurons, mediates a sex-dependent transition to chronic pain; however, evidence is lacking on which exact TLR4-expressing cells are responsible. We used complementary pharmacologic and transgenic approaches in mice to more specifically manipulate myeloid-lineage TLR4 and outline its contribution to the transition from acute-to-chronic CRPS based on three key variables: location (peripheral vs central), timing (prevention vs treatment), and sex (male vs female). We demonstrate that systemic TLR4 antagonism is more effective at improving chronic allodynia trajectory when administered at the time of injury (early) in the tibial fracture model of CRPS in both sexes. In order to clarify the contribution of myeloid-lineage cells peripherally (macrophages) or centrally (microglia), we rigorously characterize a novel spatiotemporal transgenic mouse line, Cx3CR1-CreERT2-eYFP;TLR4fl/fl (TLR4 cKO) to specifically knock out TLR4 only in microglia and no other myeloid-lineage cells. Using this transgenic mouse, we find that early TLR4 cKO results in profound improvement in chronic, but not acute, allodynia in males, with a significant but less robust effect in females. In contrast, late TLR4 cKO results in partial improvement in allodynia in both sexes, suggesting that downstream cellular or molecular TLR4-independent events may have already been triggered. Overall, we find that the contribution of TLR4 is time- and microglia-dependent in both sexes; however, females also rely on peripheral myeloid-lineage (or other TLR4 expressing) cells to trigger chronic pain.SIGNIFICANCE STATEMENT The contribution of myeloid cell TLR4 to sex-specific pain progression remains controversial. We used complementary pharmacologic and transgenic approaches to specifically manipulate TLR4 based on three key variables: location (peripheral vs central), timing (prevention vs treatment), and sex (male vs female). We discovered that microglial TLR4 contributes to early pain progression in males, and to a lesser extent in females. We further found that maintenance of chronic pain likely occurs through myeloid TLR4-independent mechanisms in both sexes. Together, we define a more nuanced contribution of this receptor to the acute-to-chronic pain transition in a mouse model of complex regional pain syndrome.  相似文献   
66.
Paroxysmal abnormal eye movement in early infancy is one of the initial symptoms of glucose transporter 1 deficiency syndrome (GLUT1DS). We describe four early infants with transient hypoglycorrhachia presenting with abnormal eye movements. Their symptoms disappeared after the introduction of a ketogenic diet (KD), and their development was normal. Since no variants in SLC2A1 were detected, the CSF-to-blood glucose ratios (C/B) were re-examined, and within normal range. None of the four patients displayed recurrent symptoms after withdrawal from the KD. Because long-term KD has potential adverse effects and could affect the quality of life of patients and their families, re-examination of CSF glucose during late infancy should be considered in the case of absence of the SLC2A1 pathogenic variant.  相似文献   
67.
Previous reports have described laparoscopic mesh repair for lumbar hernia due to iliac crest bone harvest, but there have been no reports of reoperation with laparoscopic mesh repair for recurrent cases after laparoscopic mesh repair. Here, we describe the case of a 72-year-old Japanese woman with lumbar hernia recurrence 6 years after laparoscopic mesh repair for lumbar hernia due to iliac crest bone harvest. We performed a successful reoperation with laparoscopic mesh repair. Laparoscopic surgery should be considered to elucidate the mechanism of recurrence, previous mesh position, and the area that must be covered to prevent recurrence again.  相似文献   
68.
Conservation Genetics Resources - We have developed microsatellite DNA markers for Mesopodopsis orientalis (Tattersall 1908), a widely distributed mysid crustacean in shallow waters of the coastal...  相似文献   
69.
AIMS: We investigated the relationship between interleukin (IL)-6 and coagulation, i.e. whether changes in the plasma IL-6 are associated with those in coagulation markers (D dimer and fibrinogen) after glycaemic control with sulphonylurea or insulin in poorly controlled patients with Type 2 diabetes. METHODS: We studied 42 patients with Type 2 diabetes, including 19 subsequently treated with sulphonylurea, 23 treated with insulin and 48 control subjects. All patients were in poor glycaemic control and were hospitalized for 3 weeks. At the beginning and end of treatment, we measured plasma concentrations of IL-6, fibrinogen, and D dimer. RESULTS: Plasma concentrations of IL-6 and D dimer were significantly higher in diabetic patients than in controls (P<0.0001 for both). In all patients with diabetes, the plasma concentration of IL-6 decreased significantly (P<0.001) after treatment. Changes in the plasma IL-6 during hospitalization were positively correlated with those in plasma D dimer and fibrinogen (r=0.664, P<0.0001; r=0.472, P=0.0042, respectively). Treatment with sulphonylurea or insulin caused a similar fall in the plasma IL-6 concentration with a concomitant decrease in the BMI and an equal improvement in glycaemia. CONCLUSIONS: In poorly controlled patients with Type 2 diabetes, plasma IL-6 concentrations were reduced significantly even by short-term metabolic control. As changes in the plasma concentrations of D dimer are related to plasma IL-6, plasma IL-6 may reflect a pro-coagulant as well as an inflammatory state in patients with Type 2 diabetes.  相似文献   
70.
[Purpose] The efficacy of diffusion tensor imaging in the prediction of motor outcomes and activities of daily living function remains unclear. We evaluated the most appropriate diffusion tensor parameters and methodology to determine whether the region of interest- or tractography-based method was more useful for predicting motor outcomes and activities of daily living function in stroke patients. [Subjects and Methods] Diffusion tensor imaging data within 10 days after stroke onset were collected and analyzed for 25 patients. The corticospinal tract was analyzed. Fractional anisotropy, number of fibers, and apparent diffusion coefficient were used as diffusion tensor parameters. Motor outcomes and activities of daily living function were evaluated on the same day as diffusion tensor imaging and at 1 month post-onset. [Results] The fractional anisotropy value of the affected corticospinal tract significantly correlated with the motor outcome and activities of daily living function within 10 days post-onset and at 1 month post-onset. Tthere were no significant correlations between other diffusion tensor parameters and motor outcomes or activities of daily living function. [Conclusion] The fractional anisotropy value of the affected corticospinal tract obtained using the tractography-based method was useful for predicting motor outcomes and activities of daily living function in stroke patients.Key words: Stroke, Diffusion tensor tractography, Activities of daily living function  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