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   9203篇
  免费   433篇
  国内免费   45篇
耳鼻咽喉   234篇
儿科学   248篇
妇产科学   85篇
基础医学   1138篇
口腔科学   193篇
临床医学   625篇
内科学   2033篇
皮肤病学   387篇
神经病学   715篇
特种医学   304篇
外科学   1089篇
综合类   76篇
预防医学   339篇
眼科学   113篇
药学   823篇
中国医学   37篇
肿瘤学   1242篇
  2023年   71篇
  2022年   126篇
  2021年   213篇
  2020年   109篇
  2019年   139篇
  2018年   178篇
  2017年   155篇
  2016年   146篇
  2015年   156篇
  2014年   234篇
  2013年   269篇
  2012年   476篇
  2011年   461篇
  2010年   325篇
  2009年   271篇
  2008年   401篇
  2007年   491篇
  2006年   495篇
  2005年   399篇
  2004年   447篇
  2003年   414篇
  2002年   399篇
  2001年   265篇
  2000年   297篇
  1999年   285篇
  1998年   99篇
  1997年   97篇
  1996年   87篇
  1995年   86篇
  1994年   77篇
  1993年   55篇
  1992年   198篇
  1991年   175篇
  1990年   163篇
  1989年   170篇
  1988年   141篇
  1987年   145篇
  1986年   147篇
  1985年   95篇
  1984年   84篇
  1983年   69篇
  1982年   45篇
  1979年   51篇
  1978年   31篇
  1975年   32篇
  1972年   31篇
  1969年   34篇
  1968年   31篇
  1967年   40篇
  1966年   36篇
排序方式: 共有9681条查询结果,搜索用时 15 毫秒
81.
AIM: To investigate the effect of pre-existing fetal inflammation on hemodynamics during the first postnatal 24 h in extremely premature infants or= 3 than infants with no fetal inflammation (49% vs 17%) (P=0.04). Infants with fetal inflammation had significantly higher heart rate (P=0.005), catecholamine index (P=0.019) and volume load (P=0.021). CONCLUSION: Histological evidence of fetal inflammation in extremely premature infants is associated with circulatory disturbances over the first 24 h of life and increases in the incidence of IVH >or= 3.  相似文献   
82.
Presenting continuous outcomes in Summary of Findings tables presents particular challenges to interpretation. When each study uses the same outcome measure, and the units of that measure are intuitively interpretable (e.g., duration of hospitalization, duration of symptoms), presenting differences in means is usually desirable. When the natural units of the outcome measure are not easily interpretable, choosing a threshold to create a binary outcome and presenting relative and absolute effects become a more attractive alternative.When studies use different measures of the same construct, calculating summary measures requires converting to the same units of measurement for each study. The longest standing and most widely used approach is to divide the difference in means in each study by its standard deviation and present pooled results in standard deviation units (standardized mean difference). Disadvantages of this approach include vulnerability to varying degrees of heterogeneity in the underlying populations and difficulties in interpretation. Alternatives include presenting results in the units of the most popular or interpretable measure, converting to dichotomous measures and presenting relative and absolute effects, presenting the ratio of the means of intervention and control groups, and presenting the results in minimally important difference units. We outline the merits and limitations of each alternative and provide guidance for meta-analysts and guideline developers.  相似文献   
83.
Heterozygous familial hypercholesterolemia (HeFH) is a genetic disorder that elevates low-density lipoprotein cholesterol and increases the risk of premature atherosclerotic cardiovascular disease (ASCVD). However, despite their atherogenic lipid profiles, the cardiovascular risk of HeFH varies in each individual. Their variety of phenotypic features suggests the need for better risk stratification to optimize their therapeutic management. The current review summarizes three potential approaches, including (1) definition of familial hypercholesterolemia (FH)-related risk scores, (2) genetic analysis, and (3) biomarkers. The International Atherosclerosis Society has recently proposed a definition of severe FH to identify very high-risk HeFH subjects according to their clinical characteristics. Furthermore, published studies have shown the association of FH-related genetic phenotypes with ASCVD, which indicates the genetic analysis’s potential to evaluate individual cardiovascular risks. Biomarkers reflecting disease activity have been considered to predict the formation of atherosclerosis and the occurrence of ASCVD in HeFH subjects. Incorporating these risk stratifications will be expected to allocate adequate intensity of lipid-lowering therapies in HeFH subjects, which ultimately improves cardiovascular outcomes.  相似文献   
84.
Duloxetine is widely used for pain control and depressive syndromes. One of its potential side effects is syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Duloxetine-induced SIADH causes hyponatremia, which leads to a variety of symptoms and has previously been reported in the elderly. In the present case, we experienced a case of the rapid onset of SIADH in a super-elderly woman receiving low-dose duloxetine. Elderly patients tend to have lower duloxetine doses and an earlier onset than non-elderly patients. When hyponatremia occurs after duloxetine administration, duloxetine-induced SIADH should be considered, especially in high-risk elderly patients, regardless of the duloxetine dose or duration of treatment.  相似文献   
85.
A tyrosine kinase adaptor protein containing pleckstrin homology and SH2 domains (APS) is rapidly and strongly tyrosine phosphorylated by insulin receptor kinase upon insulin stimulation. The function of APS in insulin signaling has heretofore remained unknown. APS-deficient (APS(-/-)) mice were used to investigate its function in vivo. The blood glucose-lowering effect of insulin, as assessed by the intraperitoneal insulin tolerance test, was increased in APS(-/-) mice. Plasma insulin levels during fasting and in the intraperitoneal glucose tolerance test were lower in APS(-/-) mice. APS(-/-) mice showed an increase in the whole-body glucose infusion rate as assessed by the hyperinsulinemic-euglycemic clamp test. These findings indicated that APS(-/-) mice exhibited increased sensitivity to insulin. However, overexpression of wild-type or dominant-negative APS in 3T3L1 adipocytes did not affect insulin receptor numbers, phosphorylations of insulin receptor, insulin receptor substrate-1, or Akt and mitogen-activated protein kinase. The glucose uptake and GLUT4 translocation were not affected by insulin stimulation in these cells. Nevertheless, the insulin-stimulated glucose transport in isolated adipocytes of APS(-/-) mice was increased over that of APS(+/+) mice. APS(-/-) mice also showed increased serum levels of leptin and adiponectin, which might explain the increased insulin sensitivity of adipocytes.  相似文献   
86.
BackgroundOxygenated right ventricular assist device (oxyRVAD) placement has become more streamlined with the introduction of the dual-lumen pulmonary artery cannula. Peripherally cannulated oxyRVAD may provide oxygenation support with right heart support as an alternative to venoarterial extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation.MethodsA single-institution, retrospective analysis was performed on patients placed on oxyRVAD with a dual-lumen pulmonary artery cannula with the intention of bridging to lung transplantation in 2019.ResultsFour patients with idiopathic pulmonary fibrosis were placed on oxyRVAD as a bridge to transplantation. Two patients were extubated and ambulated while waiting for a lung offer, and two patients required conversion to venoarteriovenous ECMO (VAV ECMO) from oxyRVAD. The median waiting time for extracorporeal life support (ECLS) was 42 h. All patients underwent double lung transplantation. Two patients stayed on oxyRVAD, and one patient was placed on venovenous ECMO (VV ECMO) after transplantation. Primary graft dysfunction score at 72 h after transplantation was grade 1 in three patients and grade 3 in one patient.ConclusionsPeripherally cannulated oxyRVAD with percutaneous dual-lumen venous cannula could be an ambulatory bridge for lung transplantation. It is unknown whether oxyRVAD is feasible as a long-term bridge to lung transplantation.  相似文献   
87.
Background: Although the association between asthma control and body mass index (BMI) has been thoroughly investigated, most of this work has focused on the influence on asthma incidence or the effect of obesity on asthma control. To date, there have been no published studies on the influence of underweight on asthma control.Methods: The aim of this study was to investigate the influence of underweight, as defined by the Japan Society for the Study of Obesity (JASSO), on asthma control in Japanese asthmatic patients. Using data from questionnaire surveys administered by the Niigata Asthma Treatment Study Group, we compared asthma control, as measured by the Asthma Control Test (ACT), between a normal weight group (18.5 kg/m2 =< BMI < 25 kg/ m2) and an underweight group (BMI < 18.5 kg/m2).Results: Of the asthmatic patients who completed the 2008 and 2010 surveys, 1464 and 1260 cases were classified as being in the normal weight group, and 174 and 155 cases were classified as being in the underweight group. The ACT score (median, [interquartile range]) in the underweight group in 2008 (22, [19-24]) and 2010 (23, [19-25]) was significantly lower than that in the normal group in 2008 (23, [20-25]) and in 2010 (24, [21-25]).Conclusions: This study is the first, large-scale investigation of the influence of underweight on asthma control, and we have confirmed an adverse influence in a clinical setting. A potential mechanism for this interaction was unknown. Further investigation will be required.  相似文献   
88.
One mechanism that surface cells can use to regulate intracellular pH is Na+/H+ exchange. The presence of another means to modify intracellular pH, HCO3-, was investigated, as were the effects of cyclic adenosine monophosphate and prostaglandins on an intracellular proton gradient. Isolated surface cells were preincubated in NH4+ to establish an intracellular proton gradient, which was measured using acridine orange. The addition of HCO3- causes gradient dissipation, an effect sensitive to 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid but not to extracellular chloride. The HCO3--evoked dissipation of the proton gradient is diminished by cyclic adenosine monophosphate, isobutyl-methylxanthine, and prostaglandin E2, but not by prostacyclin. The Na+-evoked dissipation of the gradient is diminished by cyclic adenosine monophosphate and isobutylmethylxanthine, but not by prostaglandin E2 or prostacyclin. Cyclic adenosine monophosphate, isobutylmethylxanthine, and the prostaglandins are without effect in the absence of Na+ or HCO3-. The data suggest that extracellular HCO3- influences an intracellular proton gradient, but the precise mechanism involved is not established in this study. The data may also explain why prostaglandins are in some instances not cytoprotective for surface cells.  相似文献   
89.
Interactions between antiserum (rabbit anti-human normal thyroglobulin-serum) and human thyroglobulin preparations (obtained from the tissues of the normal thyroid gland, thyroid adenoma, and carcinoma) were compared by inhibition effect with the binding between 131I-labeled standard thyroglobulin and antiserum, set up by a double antibody RIA. Thyroglobulins isolated from normal glands (designated as Nor-Tg) have a high affinity to the antiserum. In contrast, thyroglobulins in follicular adenoma or adenomatous goiter (designated as Ad-Tg) decrease the potency of the affinity to the antiserum. Furthermore, thyroglobulins in papillary or follicular carcinoma (designated as Ca-Tg) markedly decrease such a potency. With the t-test, the inhibition curves of Nor-Tgs are almost parallel to each other. Most of the inhibition curves of Ad-Tgs and Ca-Tgs are not parallel to the curve of Nor-Tg 1 (P-value for non-parallelism less than or equal to 0.05). Therefore, it seems that Tg preparations obtained from tumor tissue are heterogeneous in terms of specificity and/or affinity to antiserum, judging from the results of the non-parallel inhibition curves. The present results also show that the contribution of iodine content in Tg has little or no effect on the nature of Tg-immunogenicity.  相似文献   
90.
A 76 year old woman had suffered from chest pain, back pain, and dysphagia for 8 months. She was diagnosed as having a thoracic aortic aneurysm by chest X-ray and chest enhanced computed tomography. Simultaneously, severe dysphagia developed. Chest enhanced computed tomography and chest aortic aortography at our hospital demonstrated a saccular descending thoracic aortic aneurysm. Esophagography demonstrated that the esophagus was compressed by the aneurysm; therefore, a graft replacement for the saccular descending thoracic aortic aneurysm was performed on February 17th, 1998. A left sided 6th intercostal approach was made, and graft replacement for the aneurysm using a 22 mm Hemashield prosthetic graft was performed under temporary bypass from the thoracic aorta just distal to the left subclavian artery and to the left femoral artery. The postoperative course was uneventful, the severe dysphagia improved dramatically, but a pleural effusion of 1000 ml collected 3 weeks after the operation. Surgical cases of saccular descending thoracic aortic aneurysm with dysphagia are rare, and with this in mind, we report this case to the the medical literature.  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