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   2445篇
  免费   135篇
  国内免费   42篇
耳鼻咽喉   5篇
儿科学   21篇
妇产科学   21篇
基础医学   303篇
口腔科学   155篇
临床医学   81篇
内科学   253篇
皮肤病学   730篇
神经病学   93篇
特种医学   14篇
外科学   112篇
综合类   165篇
预防医学   165篇
眼科学   15篇
药学   395篇
中国医学   48篇
肿瘤学   46篇
  2023年   16篇
  2022年   49篇
  2021年   71篇
  2020年   32篇
  2019年   43篇
  2018年   48篇
  2017年   52篇
  2016年   51篇
  2015年   49篇
  2014年   87篇
  2013年   119篇
  2012年   90篇
  2011年   110篇
  2010年   94篇
  2009年   84篇
  2008年   97篇
  2007年   86篇
  2006年   84篇
  2005年   67篇
  2004年   78篇
  2003年   67篇
  2002年   68篇
  2001年   56篇
  2000年   44篇
  1999年   75篇
  1998年   66篇
  1997年   52篇
  1996年   71篇
  1995年   74篇
  1994年   57篇
  1993年   45篇
  1992年   62篇
  1991年   49篇
  1990年   38篇
  1989年   43篇
  1988年   33篇
  1987年   25篇
  1986年   27篇
  1985年   45篇
  1984年   41篇
  1983年   48篇
  1982年   27篇
  1981年   16篇
  1980年   17篇
  1979年   15篇
  1978年   10篇
  1977年   9篇
  1976年   12篇
  1975年   12篇
  1972年   4篇
排序方式: 共有2622条查询结果,搜索用时 0 毫秒
41.
BackgroundCommon salt is a safe, effective and cheap home-made remedy for umbilical granuloma. The aim of this scoping review is to identify and summarize the available evidence and examine the research conducted on salt treatment for umbilical granuloma.MethodsA literature search was performed in the second week of September, 2022 using Google scholar, PubMed, MEDLINE and EMBASE databases using the keywords ‘umbilical granuloma’ and ‘salt treatment’ to identify all English articles pertaining to salt treatment for umbilical granuloma. Tables were made to summarize the methodological characteristics, results and the dosage regimens of salt used by different authors. The Cochrane Collaboration's tool was used for assessing risk of bias in RCTs. The indexing statuses of the journals publishing these studies were also noted. The overall efficacy with the use of common salt was calculated by adding the success rates mentioned in each study.ResultsTwenty-four articles (2 systematic reviews, 6 Randomized Controlled Trials, 11 prospective cohort studies, 1 case control study, 3 retrospective case series and 1 case report) were included. An overall 93.91% success rate (1033/1100) was seen with common salt application, without any reports of complications/recurrences.ConclusionTopical application of common salt for umbilical granulomas is simple, effective and inexpensive. This scoping review provides a broader outlook at the existing level of evidence and may help in planning interventional comparative studies, so that recommendations can be formulated. It also highlights a lack of properly designed randomized controlled trials on this topic.Level of EvidenceI.  相似文献   
42.
OBJECTIVE: Elevated cortisol levels are associated with confusion and poor outcome after stroke. Dehydroepiandrosterone sulphate (DS), the most abundant adrenal androgen may act as an anti-glucocorticoid. An altered regulation of these steroids may affect numerous brain functions, including neuronal survival. The purpose of this study was to investigate serum cortisol and DS levels and the cortisol/DS ratio early after stroke and relate our findings to the presence of disorientation and mortality. DESIGN: Patients with acute ischaemic stroke (n = 88, 56 men and 32 women) admitted to a stroke unit were investigated with repeated clinical assessments and scores for degree of confusion, extent of paresis and level of functioning. Serum cortisol (C) and DS were measured on day 1 and/or day 4. Data for 28-day and 1-year mortality are presented. A control group of 65 age-matched healthy individuals was used. Multivariate analyses of mortality rates in the different tertiles or sixtiles of serum cortisol were performed with logistic regression, adjusting for age, sex, diabetes and level of consciousness. RESULTS: There was no difference in serum cortisol levels on day 1 for stroke patients when compared with control group values. Initial cortisol levels were significantly higher in the patients with acute disorientation versus orientated patients (P < 0.05). Cortisol levels on day 1 were an independent predictor of 28-day mortality, and patients with low cortisol levels (<270 nmol L(-1)) and increased levels (>550 nmol L(-1)) both had an increased 1-year mortality. DS levels on day 1 were significantly elevated in stroke patients. CONCLUSION: Hypercortisolism is associated with cognitive dysfunction early after ischaemic stroke. High and low circulating cortisol levels are associated with increased mortality after stroke. DS levels were not associated with clinical outcome.  相似文献   
43.
Albuminuria reflects widespread vascular damage   总被引:39,自引:4,他引:39  
Summary Albuminuria in Type 1 (insulin-dependent) diabetes is not only an indication of renal disease, but a new, independent risk-marker of proliferative retinopathy and macroangiopathy. The coincidence of generalised vascular dysfunction and albuminuria, advanced mesangial expansion, proliferative retinopathy, and severe macroangiopathy suggests a common cause of albuminuria and the severe renal and extrarenal complications associated with it. Enzymes involved in the metabolism of anionic components of the extracellular matrix (e.g. heparan sulphate proteoglycan) vulnerable to hyperglycaemia, seem to constitute the primary cause of albuminuria and the associated complications. Genetic polymorphism of such enzymes is possibly the main reason for variation in susceptibility.Given by T.Deckert as Claude Bernard lecture, Paris 1988  相似文献   
44.
Vinblastine a DNA non-intercalating agent has wide application against several human neoplasms, and found to cause cytogenotoxicity. In this study, clastogenotoxicity of vinblastine (1.5?mg/kg b w) and its prevention by caffeine at different doses (25, 50 and 100?mg/kg b w) administered intraperitoneally was assessed in in vivo mice. It was found that micronucleus level had decreased significantly (up to 28.8%) in 100?mg caffeine treated group at 30?h post treatment. However, it did not exhibit protective effect against chromosomal aberration in spaermatogonial cells at 24?h post treatment. The frequencies of aberrant primary spermatocytes had decreased significantly in 25 and 100?mg caffeine at 4th week of post treatment. Similarly, in 100?mg of caffeine administered, abnormal sperm level had reduced (4.01%) significantly at 8th week post treatment. Thus, caffeine decreased the vinblastine induced chromosomal aberrations and mitotic index in bone marrow cells. In conclusion, this study shows that caffeine exerts protective effect against vinblastin induced cytogenotoxicity. Further studies on molecular mechanism are interesting in order to develop it as an effective drug in cancer chemotherapy.  相似文献   
45.
A number of abnormalities of glycosaminoglycan metabolism have been reported in diabetes mellitus. These include anomalous synthesis, catabolism and sulphation. In this review glycosaminoglycan metabolism in diabetes mellitus is discussed with reference to its possible impact on glomerular basement membrane permeability, and on the physiology and metabolism of glomerular resident cells, specifically of the mesangium. Experimental results demonstrating favourable therapeutic activities of some glycosaminoglycans in mesangioproliferative glomerulitis and diabetic nephropathy are reported. These pharmacological actions do not depend on the well-known anticoagulative activity of glycosaminoglycans, but most probably on their antiproliferative effect. A more complex role of glycosaminoglycans in the pathogenesis of diabetic nephropathy is suggested.  相似文献   
46.
Nickel is a common environmental pollutant that can impair the lung, but the underlying mechanisms have not yet been fully elucidated. Furthermore, natural products are generally used to inhibit cell damage induced by heavy metal. Resveratrol possesses wide biological activities, including anti‐inflammation and antioxidative stress. This study was conducted to explore the toxicity of nickel on human bronchial epithelial (BEAS‐2B) cells and evaluate the protective effect of resveratrol. The results showed that nickel could induce cell apoptosis, increase oxidative stress, and promote the expression of pro‐inflammatory cytokines, including tumor necrosis factor‐α, interleukin (IL)‐1β, IL‐6, IL‐8, C‐reaction protein. Western blot analysis showed that nickel activated p38 mitogen‐activated protein kinase (MAPK), nuclear factor‐kappa B, and nucleotide‐binding oligomerization domain‐like receptor pyrin‐domain‐containing protein 3 pathways, while resveratrol could reverse these effects. Our results suggested that resveratrol could protect BEAS‐2B cells from nickel‐induced cytotoxicity. Therefore, resveratrol is a potential chemopreventive agent against nickel‐induced lung disease.  相似文献   
47.
We have studied the relationship between the prolaction (PRL) release induced by thyroliberin (TRH) and theophylline and the formation and inactivation of adenosine 3', 5'-cyclic monophosphate (cyclic AMP) in cultured rat-pituitary cells (GH3 cells). TRH, which stimulated prolactin release, increased cyclic AMP formation and stimulated transiently both the low- and high-Km cyclic phosphodiesterases. The maximal effect on the phosphodiesterase was observed at 30 mM TRH. The stimulatory effect of TRH on the activity of the cyclic AMP phosphodiesterases was duplicated by incubation of the cells with cyclic AMP (2-10 mM). In washed particulate GH3 cell fractions, TRH increased the adenylyl cyclase activity up to 180%. Treatment of GH3 cells with theophylline stimulated the release of PRL and inhibited cyclic AMP degradation probably leading to the measured increase in cellular concentrations of the nucleotide. The effects of TRH and theophylline on cellular cyclic AMP concentrations and on PRL release were additive. There was a positive correlation between PRL release and cellular cyclic AMP concentration (r = 0.97). The elevations observed in cellular cyclic AMP concentration after TRH treatment are due to increased formation which in turn leads to phosphodiesterase activation. Therefore, cyclic AMP formation appears to be an intermediary step in the stimulus-secretion coupling caused by the tripeptide.  相似文献   
48.
目的:探讨镍铬合金烤瓷冠配戴者中的尿镍和尿铬水平是否与机体的肾功能损伤有关。方法:对795例镍铬合金烤瓷冠配戴者进行烤瓷冠修复的问卷调查,尿镍、铬测定和血、尿肾功能生化指标测定,采用SPSS12.0软件包进行t检验、单因素方差分析和Logistic回归分析,探讨尿镍、铬水平与肾功能指标间的关系。结果:根据尿镍水平,将研究对象均分为3组(<38、38~90和≥90μg/mol肌酐)后,尿镍水平为38~90μg/mol肌酐剂量组,血肌酐明显升高,但肾小球滤过率的估计值(eGFR)明显下降,各组间不存在线性趋势,未观察到血和尿中其他各肾功能生化指标在不同尿镍剂量组间的差异。不同尿铬剂量组间(<38、38~88和≥88μg/mol肌酐),血生化指标无显著改变,但尿N-乙酰-β-D-氨基葡糖苷酶(UNAG)和尿视黄醇结合蛋白(URBP)随剂量上升呈现下降趋势。各尿镍和尿铬剂量组间eGFR的异常率和各尿肾功能指标的异常率均无显著改变。结论:镍铬合金烤瓷冠配戴者尿中镍和铬的排泄水平与机体肾损伤无关。  相似文献   
49.
50.
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