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   8893篇
  免费   55篇
  国内免费   3篇
耳鼻咽喉   124篇
儿科学   723篇
妇产科学   564篇
基础医学   686篇
口腔科学   60篇
临床医学   444篇
内科学   1244篇
皮肤病学   208篇
神经病学   371篇
特种医学   703篇
外科学   1989篇
综合类   83篇
预防医学   651篇
眼科学   176篇
药学   416篇
中国医学   3篇
肿瘤学   506篇
  2022年   1篇
  2020年   1篇
  2019年   2篇
  2018年   990篇
  2017年   1099篇
  2016年   581篇
  2015年   305篇
  2014年   213篇
  2013年   152篇
  2012年   909篇
  2011年   284篇
  2010年   25篇
  2009年   33篇
  2008年   32篇
  2007年   41篇
  2006年   45篇
  2005年   1225篇
  2004年   1845篇
  2003年   1038篇
  2002年   116篇
  2001年   8篇
  2000年   2篇
  1999年   2篇
  1998年   1篇
  1966年   1篇
排序方式: 共有8951条查询结果,搜索用时 15 毫秒
31.
Synthesis of vitamin D takes place in the skin under the effect of sunlight. The Indian subcontinent is situated between 8.4° N and 37.6° N latitudes and has adequate sunshine throughout the year. Thus, it has been presumed that Indians are vitamin D sufficient. We measured serum 25-hydroxy vitamin D [25(OH)D] (n=92) and 1,25-dihydroxy vitamin D [1, 25(OH)2D] (n=65) levels in healthy hospital staff, using 125I radioimmunoassay. Serum intact parathyroid hormone (PTH) concentration was estimated by immunoradiometric assay. Bone mineral density was estimated using a dual energy X-ray absorptiometer (HologicR QDR 4500A). Using a serum 25(OH)D level of 15 ng/ml as a cutoff, 66.3% (61/92) of the subjects were found to be vitamin D deficient. Of these, 20.6% (19/92) subjects had severe vitamin D deficiency (<5 ng/ml), 27.2% (25/92) had moderate vitamin D deficiency (5–9.9 ng/ml), while 18.5% (17/92) had mild vitamin D deficiency (10–14.9 ng/ml). When a serum 25(OH)D level of 20 ng/ml was used as a cutoff, 78.3% subjects were diagnosed to be vitamin D deficient/insufficient. The serum 1,25(OH)2D level was within the normal range (40.6±20.1 pg/ml; mean ± SD). Mean (±SD) serum intact PTH, estimated in a limited number of subjects (n=15), was 72.3 (±21.0) pg/ml (range 36–100 pg/ml). There was a significant correlation between daily sun exposure and 25(OH)D levels (r=0.731, P<0.001). The serum 25(OH)D level correlated with BMD at the femoral neck and Ward's triangle (r=0.50, P=0.020 and r=0.46, P=0.037, respectively). Our findings show that vitamin D deficiency is common in urban north Indian hospital staff. The possible reasons include inadequate sunlight exposure and skin pigmentation in Indians. The serum 1,25(OH)2D level is not a good indicator of vitamin D deficiency. A low serum 25(OH)D level is possibly one of the reasons for lower bone mineral density among Indians.  相似文献   
32.
Wu F  Wang ZB  Chen WZ  Zhu H  Bai J  Zou JZ  Li KQ  Jin CB  Xie FL  Su HB 《Annals of surgical oncology》2004,11(12):1061-1069
Background: High intensity focused ultrasound (HIFU) is a noninvasive treatment modality that induces complete coagulative necrosis of a deep tumor through the intact skin. The current study was conducted to determine the safety, efficacy, and feasibility of extracorporeal HIFU in the treatment of patients with hepatocellular carcinoma (HCC).Methods: A total of 55 patients with HCC with cirrhosis were enrolled in this prospective, nonrandomized clinical trial. Among them, 51 patients had unresectable HCC. Tumor size ranged from 4 to 14 cm in diameter with mean diameter of 8.14 cm. According to tumor, node, metastasis (TNM) classification, 15 patients corresponded to stage II, 16 to stage IIIA, and 24 to IIIC. All patients had HIFU, and the median number of HIFU session was 1.69. Safety and efficacy of HIFU were assessed in this trial.Results: No severe side effect was observed in the patients treated with HIFU. Follow-up imaging showed an absence of tumor vascular supply and the shrinkage of treated lesions. Serum -fetoprotein returned to normal level in 34% of patients. The overall survival rates at 6, 12, and 18 months were 86.1%, 61.5%, and 35.3%, respectively. The survival rates were significantly higher in patients in stage II than those in stage IIIA (P = .0132) and in stage IIIC (P = .0265).Conclusion: As a noninvasive therapy, HIFU appears to be effective, safe, and feasible in the treatment of patients with HCC. It may play an important role in the ablation of large tumors.  相似文献   
33.
Background Laparoscopic hepatic artery infusion pump (LHAIP) placement is a novel treatment option for patients with colorectal liver metastases. This study investigates technical difficulties with regard to variant hepatic arteries and the preliminary outcomes for patients treated with LHAIP placement.Methods Between March 1998 and January 2003, 38 patients with colorectal metastases confined to the liver, 35 (92%) of who had prior systemic chemotherapy that failed, were treated with LHAIP.Results Twelve patients (32%) had LHAIP placement only, and 26 (68%) had pump placement combined with laparoscopic radiofrequency ablation (LRFA; 24 patients) and/or liver resection (2 patients). Variant hepatic arterial (HA) anatomy was present in 18 patients (47%). The presence of a variant HA did not increase pump complications, operative time, or blood loss (P .20) or decrease the functional time of pump use (P = .91) in comparison with normal anatomy. In all patients with a variant HA, laparoscopic ligation of the variant vessel and/or cannulation of nongastroduodenal artery resulted in complete hepatic perfusion. Three misperfusions identified intraoperatively with use of methylene blue injection were corrected by laparoscopic ligation (two) or postoperative angioembolization (one). Postoperative pump radionuclide flow studies confirmed isolated hepatic artery infusion in all cases. There was a 13% pump-related complication rate. During a median follow-up of 11 months (0.5 to 35.5 months), the actuarial rate of overall survival was 47% and the estimated median survival time was 17.5 months.Conclusions LHAIP placement is technically feasible, and variant HA is not associated with increased pump complications or decreased pump functional time.  相似文献   
34.
This research was designed to study the effects of low-power helium–neon (He–Ne) laser irradiation on random skin flap survival in rat. Fifty 50 male rats were randomly divided into five groups. On the dorsum of each rat, one full thickness random skin flap which contained no specific vessel was elevated. Groups 1 to 4 were exposed to different models of a low-power He–Ne laser. Group 5 rats received no laser treatment and were considered as the control group. The energy density of the He–Ne laser used was 0.2 J/cm2. Immediately after surgery and at day 7, the surface area of all flaps was determined. Histological and tensiometrical studies on the surviving part of the flaps were also performed. The data obtained were analyzed by ANOVA. The results showed a significant difference in the surface area of survival parts of flaps and density of blood vessels on day 7 between group 3 rats and the other groups (P=0.0188, P=0.0455). Low-power He–Ne laser irradiation of flaps without recognized blood vessels in rats, reduced vasospasm, produced vasodilation, and caused a significant increase in the surviving surface area.Presented at the 14th World Congress of the International Society for Laser Surgery and Medicine, India, 27–30th August, 2001  相似文献   
35.
The aim of this study was to find the correlation between serum p53 and carcinoma of the bladder and to investigate whether serum p53 protein can be used as a tumor marker for p53 gene alteration. The study included patients with carcinoma of the bladder and controls. Serum p53 protein estimation was done with an ELISA kit. There were 23 patients with superficial and 17 with invasive carcinoma. The median serum p53 was 31.5 U/ml in superficial and 41 U/ml in invasive cancer. This was significantly higher than the mean value (16.4 U/ml) of controls. Serum p53 rises in patients with carcinoma of the bladder and correlates with the grade of the disease .It can therefore be used as a tumor marker for bladder cancer.  相似文献   
36.
Urinary oxalate is a biomarker for calcium oxalate kidney stone disease; however, its assay is insensitive and nonspecific. Calcium oxalate monohydrate (COM) binding protein (45 kDa) is a promoter of calcium oxalate kidney disease, which is markedly upregulated by oxalate induced oxidative stress. The current study was carried out to evaluate whether COM binding protein can serve as a diagnostic marker for calcium oxalate kidney stone formers. COM binding protein was isolated, purified and antibody was raised against it in rabbits. Urine samples (24 h) were collected from patients suffering from various kidney diseases such as acute nephritis, chronic nephritis, nephrotic syndrome, calcium oxalate (CaOx) stone formers, uric acid stone formers, struvite stone formers and calcium phosphate stone formers. This COM binding protein was quantified by an in house ELISA method and the excretion was found to lie between 2 and 3 mg in control samples, while in CaOx stone formers it was detected between 11 and 19 mg. Urinary risk factors were assayed. We conclude that COM binding protein can serve as a diagnostic marker for CaOx stone formers.  相似文献   
37.
The tolerability and pharmacokinetics of risedronate after a single oral administration and during multiple oral administrations were examined in healthy adult male volunteers. In the single dose study, the dose was increased gradually from 1mg to 2.5, 5, 10, or 20mg. Subsequently, risedronate was given by multiple administration, 5mg per dosing, once daily, for 7 days. The observed adverse events, whose causality was possibly related or unknown, included headache, diarrhea, increased body temperature, increased CK-BB, and increased urinary 2-microglobulin excretion rate. However, none of these adverse events was clinically significant. The results thus showed that risedronate was well tolerated when delivered as a single administration of up to 20mg or as a multiple administration of up to 5mg/day. In the multiple dose study, changes in urinary deoxypyridinoline suggested the bone antiresorptive activity of risedronate. In the single dose study, AUC and Cmax, after the administration of risedronate at 1, 2.5, 5, 10, and 20mg, increased dose dependently, and the Tmax, t1/2, and urinary excretion rates were nearly constant. Therefore, the pharmacokinetic profile of risedronate was considered to show linearity in a dosage range of up to 20mg. Furthermore, the results obtained in the multiple administration study indicated that the plasma concentrations of risedronate reached a steady state on day 4 of administration. The plasma concentrations of risedronate after the administration of 2.5mg risedronate to the Japanese population were nearly comparable to the serum concentrations after the administration of 5mg risedronate to the United Kingdom study population.  相似文献   
38.
A 39-year-old woman with three children presented with primary severe urinary incontinence. Epispadias without exstrophy was determined in physical examination. The single-stage procedure including vulvoplasty and modified Young-Dees-Leadbetter bladder neck repair was performed to obtain sufficient cosmetic outcome and continence. Excellent functional and cosmetic results were obtained.  相似文献   
39.
We investigated glutathione S-transferase (GST) P1I le (105) Val, T1, and M1 polymorphisms in 45 patients with documented cryptogenic cirrhosis and 56 healthy control subjects. Polymerase chain reaction-based procedures were performed in the studied populations to confirm the genotypes of GSTT1, M1, and P1. Ile/Val and Val/Val GSTP1 genotypes were more frequent in the patients with cirrhosis (n = 39, 87%) than in the control subjects (n = 10; 18%) (odds ratio [OR] 34.04; 95% confidence interval [CI] 10.70 to 108.31, P < 0.001). Among these patients with cirrhosis, 16 were heterozygous and 23 were homozygous, whereas only one person in the control group was homozygous. The GSTM1 null genotype was also more prevalent in cirrhotic patients than in healthy control subjects (OR 6.83, 95% CI 2.53 to 18.42, P < 0.001). The rate of GSTT1 deletion did not show a significant difference between the two groups (OR 2.35, 95% CI 0.76 to 7.28, P = 0.111). To our knowledge, this is the first evidence that GSTP1 and GSTM1 polymorphisms may be related to the development of cirrhosis by unknown mechanisms. The significant association of cryptogenic cirrhosis with Val/Val GSTP1 genotype encoding a low detoxification activity protein implicates this polymorphism as a risk factor for the occurrence of the disease. Presented as an abstract at the Forty-Fourth Annual Meeting of The Society for Surgery of the Alimentary Tract, Orlando, Florida, May 19–22, 2003 (Poster of Distinction).  相似文献   
40.
BACKGROUND: Kawasaki disease is an acute vasculitis syndrome of unknown etiology that mainly affects the coronary arteries. The purpose of this study was to assess the agreement between dipyridamole stress technetium 99m sestamibi single photon emission computed tomography (SPECT) and coronary angiography in these patients. METHODS AND RESULTS: Forty-one consecutive patients (29 boys and 12 girls) who underwent coronary angiography were studied prospectively. Their ages at onset of the disease ranged from 2 months to 4.8 years (mean +/- SD, 1.9 +/- 1.3 years). Their ages at the time of the study ranged from 8 months to 15.3 years (6.2 +/- 4.4 years). The duration between symptom onset and the study ranged from 2 months to 12 years (4.3 +/- 4.0 years). All patients underwent dipyridamole stress Tc-99m sestamibi SPECT within 1 month of their angiographic studies. They were divided into 3 groups according to coronary angiography findings. Group A consisted of 2 patients (1 boy and 1 girl, aged 10.3 and 1.9 years, respectively) with coronary stenoses who also had aneurysms. Group B consisted of 10 patients (8 boys and 2 girls, aged 0.7-15.3 years [mean, 3.8 years]) with coronary aneurysms. Group C consisted of 29 patients (20 boys and 9 girls, aged 1.2-13.8 years [mean, 7 years]) with normal coronary angiograms. Two patients in group A (100%), 3 of 10 patients in group B (30%), and 19 of 29 patients in group C (65.5%) had myocardial perfusion defects. There was poor agreement between Tc-99m sestamibi SPECT and coronary angiography for detecting coronary stenoses (kappa = 0.07; P =.222) and aneurysms (kappa = -0.184; P =.158). CONCLUSION: Significant discordance exists between Tc-99m sestamibi SPECT and coronary angiography in patients with Kawasaki disease.  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