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   1027573篇
  免费   69538篇
  国内免费   1571篇
耳鼻咽喉   14653篇
儿科学   33838篇
妇产科学   30462篇
基础医学   149809篇
口腔科学   28212篇
临床医学   86784篇
内科学   201792篇
皮肤病学   21123篇
神经病学   79623篇
特种医学   39841篇
外国民族医学   309篇
外科学   158376篇
综合类   21190篇
一般理论   221篇
预防医学   74044篇
眼科学   23268篇
药学   78097篇
  17篇
中国医学   1975篇
肿瘤学   55048篇
  2018年   9538篇
  2015年   9269篇
  2014年   12861篇
  2013年   19455篇
  2012年   26791篇
  2011年   28685篇
  2010年   16940篇
  2009年   15947篇
  2008年   27994篇
  2007年   30332篇
  2006年   30738篇
  2005年   30258篇
  2004年   29067篇
  2003年   28236篇
  2002年   27965篇
  2001年   46534篇
  2000年   47644篇
  1999年   40536篇
  1998年   11349篇
  1997年   10372篇
  1996年   10509篇
  1995年   9919篇
  1994年   9469篇
  1993年   8666篇
  1992年   32938篇
  1991年   32367篇
  1990年   31889篇
  1989年   30990篇
  1988年   28841篇
  1987年   28173篇
  1986年   26959篇
  1985年   25562篇
  1984年   19033篇
  1983年   16650篇
  1982年   9917篇
  1981年   8680篇
  1980年   8143篇
  1979年   18159篇
  1978年   12617篇
  1977年   10979篇
  1976年   10377篇
  1975年   11309篇
  1974年   13362篇
  1973年   12908篇
  1972年   12261篇
  1971年   11351篇
  1970年   10572篇
  1969年   10251篇
  1968年   9659篇
  1967年   8376篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Beyond its impact on bone health, numerous studies have investigated the immune-regulatory properties of vitamin D and shown how its deficiency can affect outcomes in allogeneic hematopoietic stem cell transplantation (HSCT), particularly in acute or chronic graft-versus-host disease. This survey, carried out by the Transplant Complications Working Party of the European Society for Blood and Marrow Transplantation (EBMT), describes the current clinical practice discrepancies across the EBMT HSCT programs. We therefore recommend the development of evidence-based guidelines to standardize evaluation criteria and to harmonize the management of vitamin D deficiency in patients undergoing allogeneic HSCT.  相似文献   
82.
Purpose

Intermittent hypoxia training/treatment (IHT) is an emerging therapeutic approach to alleviate chronic diseases, such as diabetes. The present study investigated the effects of IHT on blood leucocyte pyruvate dehydrogenase kinase 1 (PDK-1) mRNA expression and its relationship with the changes in blood insulin level.

Methods

Seven adult healthy volunteers and 11 prediabetic patients participated in this study. A 3-week course of IHT consisted of a 40-min session of 4 cycles of 5-min 12% O2 and 5-min room air breathing per day, 3 sessions per week for 3 weeks (i.e., total 9 sessions of IHT). Plasma insulin levels and leukocyte PDK-1 mRNA expression were determined at various time points either under fasting condition or following oral glucose tolerance test (OGTT). Correlation between the IHT-induced changes in PDK-1 mRNA and insulin or glucose levels in the same serological samples was analyzed.

Results

At pre-IHT baseline, PDK-1 mRNA expression was two times higher in prediabetes than control subjects. IHT resulted in significant augmentation in PDK-1 mRNA expression (> twofold) in prediabetes at the end of 3-week IHT and remained elevated 1 month after IHT, which was correlated with a significantly reduced insulin release and lower blood glucose after glucose loading with OGTT.

Conclusion

IHT can trigger beneficial effects in normalizing blood insulin levels in prediabetic patients under oral glucose load, which were closely correlated with an enhanced mRNA expression of PDK-1 in leukocytes. Further clinical trials are warranted to validate the utility of IHT as a non-invasive complementary therapy against diabetes-associated pathologies.

  相似文献   
83.
84.
85.
86.
The anti-epileptic drugs phenobarbital and valproic acid have an extremely strong negative effect on cognitive processes such as learning and memory in the developing brain. We examined whether or not curcumin has protective effects on neuronal injury caused by these drugs in the developing rat brain. Young male Wistar rats were studied in two groups, a 7 days old and a 14 days old group (35 rats in each). Both groups were then divided into 7 sub-groups as the control, curcumin, dimethylsulfoxide, phenobarbital, valproic acid, phenobarbital + curcumin, and valproic acid + curcumin groups (n = 5 in each group). At 24 h after the intraperitoneal injection of the compounds, the rats were sacrificed, and the hippocampal tissue was subjected to stereological analysis with the optical fractionation method. Total numbers of neurons in the hippocampus of the 7 days old and 14 days old rats were calculated. It was found that treatment with phenobarbital resulted in a loss of 43% of the neurons, and valproic acid induced a loss of 57% of the neurons in the 7 days old rats. Curcumin prevented this loss significantly with only 19% in the phenobarbital group and 41% in the valproic acid group. In the 14 days old rat groups, phenobarbital was found to reduce the number of neurons by 30%, and valproic acid reduced it by 38%. Curcumin treatment limited neuronal loss to 3% in the phenobarbital + curcumin group and 10% in the valproic acid + curcumin group. These data strongly indicate that curcumin is a protective agent and prevents hippocampal neuronal damage induced by phenobarbital and valproic acid treatment.  相似文献   
87.
AimTo investigate clinico-pathological features of lymphoma of the lips, and review the literature.Materials and MethodsRetrospective analysis and review of English literature, 1996-2016.ResultsAnalysis included 23 cases, 7 new cases and 16 from literature, 12 M: 11 F, age 7–82 years. Four occurred in children, mean age 10.1; 19 in adults, mean 61.1 years.The lower lip was involved in the majority of cases (16, 69.56%). 14 (60.87%) were isolated to the lips, 8 (34.78%) were multifocal. Nine (39.13%) occurred in association with Sjogren's syndrome, of which one also had Hashimoto thyroiditis. IgG4-related disease and HIV were reported in one case each. The lip salivary glands were involved in most cases (19, 82.6%); 3 (13.6%) showed only cutaneous involvement.The typical presentation was single or multiple nodules (15, 65.21%), with surface ulceration in only two (8.69%). Constituent symptoms were absent in all cases, paresthesia was reported in one (4.34%). The majority (18, 78.26%) was extranodal marginal zone B-cell lymphoma - mucosa-associated lymphoid tissue lymphoma (EMZB-MALT), and one case each was mantle cell, NK-T cell, CD30 positive and plasmablastic lymphoma.ConclusionThe lips seem to have a unique pattern of non-Hodgkin lymphoma dominated by EMZB-MALT lymphoma, rarely other types. In more than half, neither Sjogren's syndrome nor other chronic inflammation was identified. Lesions tend to present as asymptomatic slowly progressing, non-ulcerated submucosal masses. Lymphoma should be considered even in the absence of constituent symptoms, as most cases showed none. Although the number of reported cases is rather small, disease course is usually prolonged and prognosis seems to be good.  相似文献   
88.
89.
Neuroscience and Behavioral Physiology - We report here a comparative (using chemical, electrical, and optical stimulation) study of the electrophysiological properties of cultured hippocampal...  相似文献   
90.
Neuroscience and Behavioral Physiology - The effects of weak electric fields with parameters close to those of the electrical activity of brain structures on neural networks in the brain have been...  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