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   43441篇
  免费   2464篇
  国内免费   142篇
耳鼻咽喉   653篇
儿科学   1982篇
妇产科学   1025篇
基础医学   5161篇
口腔科学   2075篇
临床医学   3911篇
内科学   9071篇
皮肤病学   1198篇
神经病学   3416篇
特种医学   1727篇
外科学   6604篇
综合类   175篇
一般理论   17篇
预防医学   2750篇
眼科学   1131篇
药学   2756篇
  2篇
中国医学   193篇
肿瘤学   2200篇
  2024年   44篇
  2023年   365篇
  2022年   322篇
  2021年   813篇
  2020年   516篇
  2019年   834篇
  2018年   1396篇
  2017年   988篇
  2016年   1088篇
  2015年   1040篇
  2014年   1212篇
  2013年   1928篇
  2012年   3022篇
  2011年   3529篇
  2010年   1657篇
  2009年   1056篇
  2008年   2998篇
  2007年   3238篇
  2006年   3099篇
  2005年   3093篇
  2004年   2913篇
  2003年   2711篇
  2002年   2552篇
  2001年   874篇
  2000年   994篇
  1999年   587篇
  1998年   350篇
  1997年   345篇
  1996年   296篇
  1995年   245篇
  1994年   235篇
  1993年   201篇
  1992年   124篇
  1991年   108篇
  1990年   124篇
  1989年   122篇
  1988年   106篇
  1987年   86篇
  1986年   91篇
  1985年   88篇
  1984年   73篇
  1983年   53篇
  1982年   72篇
  1981年   67篇
  1980年   62篇
  1979年   37篇
  1978年   33篇
  1977年   50篇
  1976年   42篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
A decrease of heteronymous median nerve-evoked inhibition of corticospinal projections to forearm extensor muscles was reported in a group of 10 dystonic patients by Bertolasi and colleagues in 2003. Here we tested the excitability of corticomotoneuronal connections to both wrist extensor (ECR) and flexor (FCR) muscles after conditioning stimulation of median and also radial nerve at rest in a group of 25 patients with focal hand dystonia compared to 20 healthy subjects. We also investigated the effect of the wrist dystonic posture, either in flexion or in extension, on the afferent modulation of ECR and FCR motor evolved potentials (MEPs). The heteronymous (median-induced) but also homonymous (radial-induced) inhibitions (interstimuli intervals 13-21 ms) of ECR MEP size observed in healthy subjects were decreased in patients. In addition, homonymous (median-induced) facilitation of FCR MEP size was also decreased in patients while heteronymous inhibition (radial-induced) was not. Neither the involvement of the target muscle in the dystonic posture nor the origin of the afferent volley (from a dystonic muscle) influenced the degree of impairment of afferent modulation of the MEP. These findings support the view that a global abnormal somatosensory coupling in focal hand dystonia may contribute to an inadequate motor command to wrist muscles.  相似文献   
24.
BACKGROUND/PURPOSE: The polysaccharide-rich composition of Aloe vera extracts (Aloe barbadensis Miller), often used in cosmetic formulations, may impart moisturizing properties to the product. The aim of this study was to evaluate the effect of cosmetic formulations containing different concentrations of freeze-dried Aloe vera extract on skin hydration, after a single and a 1- and 2-week period of application, by using skin bioengineering techniques. METHODS: Stable formulations containing 5% (w/w) of a trilaureth-4 phosphate-based blend were supplemented with 0.10%, 0.25% or 0.50% (w/w) of freeze-dried Aloe vera extract and applied to the volar forearm of 20 female subjects. Skin conditions in terms of the water content of the stratum corneum and of transepidermal water loss (TEWL) (Corneometer CM 825 and Tewameter TM 210) were analysed before and after a single and 1- and 2-week period of daily application. RESULTS: After a single application, only formulations supplemented with 0.25% and 0.50% (w/w) of Aloe vera extract increased the water content of the stratum corneum, while after the 2-week period application, all formulations containing the extract (0.10%, 0.25% and 0.50%) had the same effect, in both cases as compared with the vehicle. TEWL was not modified after a single and after 1- and 2-week period of application, when compared with the vehicle. CONCLUSION: Our results show that freeze-dried Aloe vera extract is a natural effective ingredient for improving skin hydration, possibly through a humectant mechanism. Consequently, it may be used in moisturizing cosmetic formulations and also as a complement in the treatment of dry skin.  相似文献   
25.
To determine the prevalence of excessive daytime sleepiness (EDS) and that of dozing and sudden onset of sleep episodes (SOS) while driving in ambulatory patients with Parkinson's disease (PD) in France, a national sample of private and public neurologists was asked to recruit the first 10 consecutive nondemented PD patients. Each patient completed a questionnaire including the Epworth Sleepiness Scale (ESS) and the likelihood of dozing off and experiencing SOS episodes behind the wheel. Clinical and demographic data were collected. One thousand six hundred and twenty‐five patients with PD were included in the survey. Twenty‐nine percent of the patients suffered from EDS (ESS score ≥10) but only 0.8% declared a high chance of dozing while driving and 0.5% reported totally unpredictable SOS episodes while driving. Risk factors for EDS were male gender, reduced activity of daily living, and a high daily levodopa equivalent dosage. Risk factors for SOS episodes while driving were an ESS score ≥10, male gender, and low Hoehn and Yahr staging. EDS is common in ambulatory patients with PD and is a major risk factor for dozing and for SOS episodes behind the wheel in patients who drive. © 2007 Movement Disorder Society  相似文献   
26.
27.
.We report five patients with Laurence-Moon-Bardet-Biedl syndrome (LMBBS) who had renal involvement. Intravenous pyelography showed bilateral or unilateral calyceal clubbing and blunting in all patients. In addition, one patient had a parapelvic cyst in the left kidney and another had bilateral lobulated renal outlines of the fetal type. One patient had a urinary concentrating defect and two patients showed increased fractional sodium excretion. Estimated tubular phosphate reabsorption values were in normal limits in all of five patients. No patient had a urine acidification defect, proteinuria, glycosuria, or hyperaminoaciduria. One patient died from end-stage renal failure. The remaining four patients had normal serum creatinine values and estimated creatinine clearances. 99mTechnetium-diethylenetriamine pentaacetate renal scanning showed prolonged and delayed concentration and delayed excretion in three of the four patients who survived. A focal scar was determined on the left kidney of one of four patients by 99mtechnetium-dimercaptosuccinic acid renal scanning. All LMBBS cases with or without renal symptoms should be routinely evaluated for renal abnormalities. Renal scanning is a valuable method, especially for determining the renal involvement in the early stage of disease. Received November 14, 1995; received in revised form and accepted May 23, 1996  相似文献   
28.
Pharmacokinetics of prednisolone in children with the nephrotic syndrome   总被引:1,自引:0,他引:1  
The aim of this study was to establish whether the criteria for the clinical effectiveness of steroids are correlated with the pharmacokinetics of prednisolone in children treated with prednisone during an attack of idiopathic nephrotic syndrome (INS). Thirteen patients with nephrosis were included. Prednisolone, prednisone and cortisol levels were measured using a specific high-performance liquid chromatography assay after an oral dose of 1 mg/kg body weight of prednisone taken at the onset of the disease. All the pharmacokinetic parameters, including the conversion of prednisone to prednisolone were similar to the data already published in children with INS. No correlation was found between the values of pharmacokinetic parameters and criteria of clinical effectiveness. Hypo-albuminaemia was significantly correlated with the area under the plasma-concentration curve but not with the elimination half-life of prednisolone. Moreover, the prednisolone elimination half-life correlated with the urinary exretion of 17-hydroxycorticosteroids achieved in the first 6h. The present study suggests that routine measurements of prednisolone kinetics do not help when assessing the treatment of children with INS.  相似文献   
29.
Indium-111 octreotide and thallium-201 scintigraphic studies were compared in 21 patients (16 with palpable and five with non-palpable lesions) suspected of having breast malignancies on the basis of mammography. Early (15 min) and late (3 h)201Tl (111 MBq) and 4-h and 24-h111In-octreotide (111–148 MBq) static planar anterior images (matrix 256×256) were obtained on separate days. Images were evaluated both visually and quantitatively. Biopsy was performed following the imaging studies. Histopathology revealed 17 breast carcinomas (15 cases of invasive ductal carcinoma, one mucinous adenocarcinoma and one intraductal carcinoma) and four benign breast lesions (two fibroadenomas, one abscess and one case of fat necrosis). The means histopathologcial tumour size (mean largest diameter) was 3.38±1.9 cm.111In-octreotide detected 16 of the 17 breast cancers (94%) while201Tl detected 13 of them (76%). Both111In-octreotide and201Tl missed one nonpalpable carcinoma showing only an isolated cluster of microcalcifications on mammography. The smallest tumour size detected by both agents 1.5×1.5 cm. Of the four benign lesions, only the breast abscess revealed both201Tl and111In-octreotide uptake.111In-octreotide scan also showed tracer uptake in five of the six patients with histologically proven axillary metastases, while four of these six patients showed201Tl uptake. The tumour/background (T/B) ratios of late111In-octreotide and201Tl images were 1.71±0.38 and 1.46±0.30 respectively (P=0.039). In this preliminary study,111In-octreotide yielded more favourable results than201Tl in the detection of breast carcinomas. However, the diagnostic efficacy of111In-octreotide imaging needs to be investigated in larger patient series.  相似文献   
30.
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