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   1488篇
  免费   105篇
  国内免费   8篇
耳鼻咽喉   5篇
儿科学   30篇
妇产科学   47篇
基础医学   216篇
口腔科学   63篇
临床医学   149篇
内科学   336篇
皮肤病学   37篇
神经病学   71篇
特种医学   34篇
外国民族医学   2篇
外科学   134篇
综合类   43篇
一般理论   1篇
预防医学   106篇
眼科学   26篇
药学   161篇
中国医学   4篇
肿瘤学   136篇
  2024年   3篇
  2023年   23篇
  2022年   58篇
  2021年   107篇
  2020年   68篇
  2019年   62篇
  2018年   71篇
  2017年   46篇
  2016年   41篇
  2015年   55篇
  2014年   59篇
  2013年   73篇
  2012年   137篇
  2011年   127篇
  2010年   67篇
  2009年   52篇
  2008年   82篇
  2007年   88篇
  2006年   78篇
  2005年   77篇
  2004年   68篇
  2003年   54篇
  2002年   43篇
  2001年   2篇
  2000年   2篇
  1999年   7篇
  1998年   4篇
  1997年   4篇
  1996年   9篇
  1995年   3篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   5篇
  1989年   4篇
  1988年   4篇
  1987年   4篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1980年   1篇
  1971年   3篇
排序方式: 共有1601条查询结果,搜索用时 15 毫秒
61.
Due to high prevalence of primary aldosteronism (PA) in the general hypertensive population, and its association with worse cardiovascular and renal outcomes, the 2016 Endocrine Society Guidelines explicitly recognize PA as a major public health issue requiring urgent attention. Its prevalence in hypertensive kidney transplant recipients (KTRs) is unknown. In this cross-sectional study, we screened KTRs with hypertension who were on ≥4 antihypertensive medications, on 3 antihypertensive medications with BP ≥ 140/90, and on potassium supplements, or were hypokalemic. 172 of 280 eligible patients successfully completed the testing. A positive screen for PA defined by an aldosterone-to-renin ratio of ≥20 and a plasma aldosterone concentration of >15 ng/dL yielded a prevalence of 15.7%. Potassium supplement requirement (52% vs 27%, P = .01) and hypokalemia (25.9% vs 4.8%, P < .01) were more common in patients who screened positive compared with those who screened negative. 67% of patients who screened positive were on potassium supplements and/or were hypokalemic. Our study is the first to systematically explore the prevalence of PA among the hypertensive KTR population, which has inherently high cardiovascular risk. Further studies are needed to determine the cardiovascular and renal risk attributable to PA, and define optimal therapy for KTRs with PA.  相似文献   
62.
The present study aimed to formulate orodispersible tablets of flutamide (FTM) to increase its bioavailability. Orodispersible tablets were prepared by direct compression technique using three different approaches namely; super-disintegration, effervescence and sublimation. Different combined approaches were proposed and evaluated to optimize tablet characteristics. Sodium starch glycolate (SSG) was used as the superdisintegrant. The prepared powder mixtures were subjected to both pre and post compression evaluation parameters including; IR spectroscopy, micromeritics properties, tablet hardness, friability, wetting time, disintegration time and in-vitro drug release. IR studies indicated that there was no interaction between the drug and the excipients used except Ludipress. The results of micromeritics studies revealed that all formulations were of acceptable to good flowability. Tablet hardness and friability indicated good mechanical strength. Wetting and dispersion times decreased from 46 to 38 s by increasing the SSG concentration from 3.33 to 6.66% w/w in tablets prepared by superdisintegration method. The F8 formulation which was prepared by combined approaches of effervescence and superdisintegrant addition gave promising results for tablet disintegration and wetting times but failed to give faster dissolution rate. The incorporation of 1:5 solid dispersion of FTM: PEG 6000 instead of the pure drug in the same formulation increased the drug release rate from 73.12 to 96.99% after 15 min. This increase in the dissolution rate may be due to the amorphization of the drug during the solid dispersion preparation. The presence of the amorphous form of the drug was shown in the IR spectra.  相似文献   
63.
Objective:Bi-allelic mutations in the wolframin gene (WFS1) cause Wolfram syndrome 1 (WS1 or DIDMOAD) characterized by non-autoimmune diabetes mellitus, optic atrophy, diabetes insipidus, sensorineural deafness, urinary tract abnormalities, and neuropsychiatric disorders. Patients presenting with an incomplete phenotype of WS1 were evaluated using homozygosity mapping and subsequent whole-exome sequencing.Methods:Four unrelated consanguineous Turkish families, including seven affected children, and their unaffected parents and siblings were evaluated. Homozygosity mapping was performed, followed by whole-exome sequencing of WFS1. Mutations were classified according to results of “in silico” analyses, protein prediction, and functional consequences.Results:Homozygosity mapping confirmed shared homozygous regions on chromosome 4 (chr4p16.1) between the affected individuals, that was absent in their unaffected siblings. Exome sequencing identified three novel (c.1215T>A, c.554G>A, c.1525_1540dup) and one known (c.1522_1523delTA) mutations in WFS1. All mutations were predicted to cause stop codon leading to early termination of protein synthesis and complete loss-of-function. All patients were found to be homozygous for the change, with parents and other unaffected siblings being carriers.Conclusion:Our study expands the mutation spectrum of WSF1 mutations with three novel mutations. Homozygosity mapping may provide enrichment for molecular genetic analysis and early diagnosis of WS1 patients with incomplete phenotype, particularly in consanguineous pedigrees.  相似文献   
64.
Objectives: We aim to describe the efficacy, safety, and characteristics of the Amplatzer Vascular Plug (AVP) II and IV “off-label” use for multiple cardiovascular occlusions in children under 10 years. Methods: Observational retrospective multicenter (2007–2020, 6 centers) review of paediatric procedures using AVP II or IV. Results: A total of 125 children (49.6% aged ≤ 1 year, 147 lesions) underwent 136 successive procedures (success rate: 98.5%) using 169 devices (109 AVP IV, 60 AVP II). The mean device diameter was 7.7 ± 3.2 mm (4–20 mm). The median AVP size to vessel diameter ratio was 1.3 (0–2). The median age and weight at implantation were 1.0 year (0.01–9.98) and 8.4 kg (1–69). Procedures were heterogeneous (55 patent ductus arteriosus (PDA), 28 collaterals, 18 sequestrations, 22 arteriovenous/veinovenous/coronary fistulas, 6 vertical veins, 6 conduits, 5 ventricular septal defects, 7 miscellaneous). Day 1 and 6-month occlusion rates were respectively 94.8% and 98.5%. Major adverse events (MAE) occurred in 5.2% of cases (no procedure-related deaths), and more frequently in weight ≤ 5 kg (p = 0.01), younger patients (p = 0.03) during PDA closure (p = 0.02) of tubular types (p = 0.02) using larger devices (p = 0.03) and AVP II (p = 0.003). Independent predictor of MAE risk was a higher AVP diameter to patient weight ratio (Odds-ratio: 2.33, 95% confidence interval 1.31–4.13, p = 0.004, optimal cut off: 1.45). Conclusions: Both AVPs are safe and effective for percutaneous occlusions in children under 10. Such devices represent an alternative “off label” use for well selected paediatric patients.  相似文献   
65.
66.
Two distinct types of CpG oligodeoxynucleotide (ODN) have been identified that differ in their capacity to stimulate antigen-presenting cells: CpG-A induces high amounts of interferon-alpha (IFN-alpha) and IFN-beta in plasmacytoid dendritic cells (PDCs), whereas CpG-B induces PDC maturation and is a potent activator of B cells but stimulates only small amounts of IFN-alpha and IFN-beta. Here we examined the ability of these CpG ODNs to enhance peptide-specific CD8+ T-cell responses in human peripheral blood mononuclear cells (PBMCs). The frequency of influenza matrix-specific "memory" CD8+ T cells was increased by both types of CpG ODN, whereas the frequency of Melan-A specific "naive" CD8+ T cells increased on stimulation with CpG-B but not with CpG-A. The presence of PDCs in PBMCs was required for this CpG ODN-mediated effect. The expanded cells were cytotoxic and produced IFN- on peptide restimulation. Soluble factors induced by CpG-A but not CpG-B increased the granzyme-B content and cytotoxicity of established CD8+ T-cell clones, each of which was IFN-alpha/-beta dependent. In conclusion, CpG-B seems to be superior for priming CD8+ T-cell responses, and CpG-A selectively enhances memory CD8+ T-cell responses and induces cytotoxicity. These results demonstrate distinct functional properties of CpG-A and CpG-B with regard to CD8 T cells.  相似文献   
67.
Transplant candidates might manifest circulating antibodies against human leukocyte antigens and nonhuman leukocyte antigens, a condition termed allosensitization. The presence of these antibodies decreases a given candidate's possible donor pool, thereby prolonging the time to transplantation. They are also associated with poorer posttransplant outcomes including increased morbidity and mortality. With the increasing use of ventricular assist devices as a bridge to transplantation, the prevalence of allosensitized transplant candidates has increased. This has implications for transplant programs in terms of donor-recipient matching and managing transplant-related complications, which are more common in this high risk cohort. Controversy exists as to the best approach in managing sensitized patients, before and after transplantation. Transplant centres have used various strategies to reduce antibody loads with mixed results being reported; moreover, it remains unclear as to whether attempts at desensitization translate into better posttransplant outcomes. As an alternative management approach, some centres participate in large organ sharing strategies and allocate organs based on the probability of finding a successful donor-recipient match. In this article, the immunological basis of allosensitization, its causes, implications, and therapeutic strategies to manage sensitized patients are reviewed. The literature in relation to desensitization therapies in heart transplant candidates is also reviewed.  相似文献   
68.

Objective

Variants of estrogen receptor α (ERα) have been associated with obesity, dyslipidemia, diabetes and blood pressure. The Middle East registers some of the highest rate of metabolic syndrome worldwide. The aim of this study is to investigate the relationship between metabolic syndrome, a clustered combination of these metabolic factors, and polymorphisms PvuII and XbaI of ERα in Lebanese Caucasian elderly overweight subjects.

Material/Methods

250 Caucasian Lebanese unrelated elderly men and women, median age 71 years, were studied. ERα intronic polymorphisms variants, PvuII and XbaI diplotypes and genotypes, were examined. Associations with metabolic syndrome, defined by the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI), and its components, namely high density lipoprotein (HDL), fasting glucose levels, blood pressure, and waist circumference were evaluated in regression models.

Results

ER α diplotypes and genotypes distributions were similar between participants with and without metabolic syndrome, in the overall group of subjects, and by gender. No consistent associations between the diplotypes and genotypes tested and metabolic syndrome, or its components, could be detected.

Conclusions

Genetic variants in ERα were not associated with metabolic syndrome or its components, in a group of 250 Lebanese Caucasian elderly participants, a group with a high prevalence of metabolic syndrome.  相似文献   
69.
Germination is of importance to improving nutritional attributes of cereal grains for human consumption. The effect of germination time on major nutrient compositions and functional properties of sorghum flour was investigated in this study. Grains of Butanua, a new Sudanese sorghum cultivar, were germinated for 0,?1,?2, and 3 days to analyze their chemical and functional properties. The contents of starch, protein, oil, foaming stability, bulk density, and least gelation concentration of sorghum flour decreased, whereas oil absorption capacity, foaming capacity, and emulsion capacity and stability enhanced with an increase in germination time. Improved functional properties of sorghum flour by germination of the grains not only make it useful and suitable for various food processing formulations, but also improve the food product quality. This new finding will beneficially help develop innovative technologies, design new types of functional foods, and promote both sorghum production and relevant food processing industry in the future.  相似文献   
70.
Synaptotagmins are integral synaptic vesicle membrane proteins that function as calcium sensors and regulate neurotransmitter release at the presynaptic nerve terminal. Synaptotagmin‐2 (SYT2), is the major isoform expressed at the neuromuscular junction. Recently, dominant missense variants in SYT2 have been reported as a rare cause of distal motor neuropathy and myasthenic syndrome, manifesting with stable or slowly progressive distal weakness of variable severity along with presynaptic NMJ impairment. These variants are thought to have a dominant‐negative effect on synaptic vesicle exocytosis, although the precise pathomechanism remains to be elucidated. Here we report seven patients of five families, with biallelic loss of function variants in SYT2, clinically manifesting with a remarkably consistent phenotype of severe congenital onset hypotonia and weakness, with variable degrees of respiratory involvement. Electrodiagnostic findings were consistent with a presynaptic congenital myasthenic syndrome (CMS) in some. Treatment with an acetylcholinesterase inhibitor pursued in three patients showed clinical improvement with increased strength and function. This series further establishes SYT2 as a CMS‐disease gene and expands its clinical and genetic spectrum to include recessive loss‐of‐function variants, manifesting as a severe congenital onset presynaptic CMS with potential treatment implications.  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