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   2497篇
  免费   136篇
  国内免费   10篇
耳鼻咽喉   27篇
儿科学   185篇
妇产科学   27篇
基础医学   318篇
口腔科学   69篇
临床医学   155篇
内科学   477篇
皮肤病学   38篇
神经病学   108篇
特种医学   50篇
外科学   341篇
综合类   50篇
一般理论   1篇
预防医学   131篇
眼科学   150篇
药学   354篇
中国医学   38篇
肿瘤学   124篇
  2023年   21篇
  2022年   56篇
  2021年   101篇
  2020年   47篇
  2019年   56篇
  2018年   76篇
  2017年   55篇
  2016年   75篇
  2015年   86篇
  2014年   122篇
  2013年   148篇
  2012年   194篇
  2011年   173篇
  2010年   117篇
  2009年   92篇
  2008年   140篇
  2007年   145篇
  2006年   119篇
  2005年   115篇
  2004年   118篇
  2003年   95篇
  2002年   74篇
  2001年   57篇
  2000年   39篇
  1999年   26篇
  1998年   10篇
  1997年   9篇
  1996年   11篇
  1995年   9篇
  1994年   11篇
  1993年   9篇
  1992年   20篇
  1991年   16篇
  1990年   21篇
  1989年   21篇
  1988年   17篇
  1987年   17篇
  1986年   16篇
  1985年   21篇
  1984年   10篇
  1983年   12篇
  1982年   5篇
  1981年   10篇
  1980年   6篇
  1979年   14篇
  1978年   9篇
  1974年   3篇
  1967年   2篇
  1965年   4篇
  1900年   1篇
排序方式: 共有2643条查询结果,搜索用时 15 毫秒
81.
82.
The present study has analysed the numbers of argyrophilic nucleolar organizer regions (AgNOR) in normal tissues and in premalignant and malignant lesions of the oral mucosa in order to assess their potential as a biological marker for tumour progression. On comparison of AgNOR numbers in different lesions, carcinomas showed the highest number (4.65±0.98) compared to leukoplakias (2.38±0.47) and normal tissues (1.53±0.39). Spindle cell carcinomas and poorly differentiated squamous cell carcinomas had higher AgNOR counts than well-differentiated carcinomas. In various clinically different types of oral leukoplakia, the lowest AgNOR counts were observed in homogenous leukoplakia and the highest in speckled leukoplakia. No significant difference in AgNOR number was observed between non-dysplastic and dysplastic leukoplakia, although a significant difference was evident between dysplastic leukoplakia and normal oral mucosa. Correlating the AgNOR count and tumour progression, a significantly high positive correlation coefficient (r=0.7969,P=0.0000) was observed.  相似文献   
83.
Multiple endocrine neoplasia type 2A and 2B (MEN-2A and MEN-2B) are autosomal dominantly inherited syndromes in which medullary thyroid cancers are associated with adrenal pheochromocytomas. A double-blind analysis of high-resolution G-banded chromosomes was performed on blood specimens from patients in four MEN-2A families and five MEN-2B (mucosal neuroma phenotype) families and from control subjects. Excluding studies on duplicate blood specimens, 9 of 11 control subjects were scored as having normal chromosomes 20, and 11 of 14 MEN-2 patients were scored as having chromosomal deletion: del(20)(p12.2p12.2) (phi 2 = 9.00; P less than 0.001). Two new mutant MEN-2B patients had apparently normal chromosomes 20. These findings demonstrate that the dominant mutation in most MEN-2A and MEN-2B families is a visible chromosome deletion within band 20p12.2.  相似文献   
84.

Background

Improvement of transcranial electrical motor-evoked potentials (TeMEPs) following untethering during tethered cord surgery (TCS) and its clinical significance have not been analyzed in the literature.

Methods

Forty-five consecutive cases of tethered cord were operated on with multimodality intraoperative neurophysiological monitoring (IONM) between February 2005 and January 2012. Intraoperative TeMEP change was classified as improvement, worsening or no change. Motor, sensory, bladder and bowel symptoms and signs were evaluated preoperatively, in the first week post-surgery and at the last follow-up (maximum of 2 years).

Results

Patient age ranged from 5 to 44 years (mean, 16?±?10 years), with 30 children. Intraoperative MEPs improved in 23 (51 %), remained the same in 21 (46.7 %) and worsened in 1 (2 %) patient. Motor improvement occurred in 7 patients and clinical improvement in 17 patients in the immediate postoperative period. Postoperative neurological worsening occurred in one patient (2.2 %). Improved and stable MEPs correlated with the motor (p?=?0.002) and clinical improvement (p?=?0.02) in the immediate postoperative period. Follow-up was available in 35 patients (77.7 %), ranging from 5 to 24 months (median, 21 months; mean, 17.7?±?6.8 months). There was late clinical improvement in 73.5 % of the patients in whom the intraoperative MEP had remained the same or improved. However, there was no statistically significant correlation between MEP change and long-term outcome.

Conclusions

Intraoperative MEP improvement occurs in about 50 % of the patients following successful untethering. This finding probably provides support to the ischemic theory of tethered cord syndrome.  相似文献   
85.
86.

Background:

Percutaneous aspiration of abscesses under ultrasonography (USG) and computer tomography (CT) scan has been well described. With recurrence rate reported as high as 66%. The open drainage and percutaneous continuous drainage (PCD) has reduced the recurrence rate. The disadvantage of PCD under CT is radiation hazard and problems of asepsis. Hence a technique of clinically guided percutaneous continuous drainage of the psoas abscess without real-time imaging overcomes these problems. We describe clinically guided PCD of psoas abscess and its outcome.

Materials and Methods:

Twenty-nine patients with dorsolumbar spondylodiscitis without gross neural deficit with psoas abscess of size >5 cm were selected for PCD. It was done as a day care procedure under local anesthesia. Sequentially, aspiration followed by guide pin-guided trocar and catheter insertion was done without image guidance. Culture sensitivity was done and chemotherapy initiated and catheter kept till the drainage was <10 ml for 48 hours. Outcome assessment was done with relief of pain, successful abscess drainage and ODI (Oswestry Disability Index) score at 2 years.

Results:

PCD was successful in all cases. Back and radicular pain improved in all cases. Average procedure time was 24.30 minutes, drain output was 234.40 ml, and the drainage duration was 7.90 days. One patient required surgical stabilisation due to progression of the spondylodiscitis resulting in instability inspite of successful drainage of abscess. Problems with the procedure were noticed in six patients. Multiple attempts (n = 2), persistent discharge (n = 1) for 2 weeks, blocked catheter (n = 2) and catheter pull out (n = 1) occurred with no effect on the outcome. The average ODI score improved from 62.47 to 5.51 at 2 years.

Conclusions:

Clinically guided PCD is an efficient, safe and easy procedure in drainage of psoas abscess.  相似文献   
87.
Correction for ‘A clinical and computational study on anti-obesity effects of hydroxycitric acid’ by Manu Tomar et al., RSC Adv., 2019, 9, 18578–18588.

The authors regret that the name of one of the authors (Raghavendra Pralhada Rao) was shown incorrectly in the original article. The corrected author list is as shown above.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.  相似文献   
88.
The study was undertaken to evaluate the parallelism between hamular-incisive-papilla plane (HIP) and the Campers plane. And to determine which part of the posterior reference of the tragus i.e., the superior, middle or the inferior of the Camper’s plane is parallel to HIP using digital lateral cephalograms. Fifty edentulous subjects with well formed ridges were selected for the study. The master casts were obtained using the standard selective pressure impression procedure. On the deepest point of the hamular notches and the centre of the incisive papilla stainless steel spherical bearings were glued to the cast at the marked points. The study templates were fabricated with autopolymerizing acrylic resin. The subjects were prepared for the lateral cephalograms. Stainless steel spherical bearings were adhered to the superior, middle, inferior points of the tragus of the ear and inferior border of the ala of the nose using surgical adhesive tape. The subjects with study templates were subjected to lateral cephalograms. Cephalometric tracings were done using Autocad 2010 software. Lines were drawn connecting the incisive papilla and hamular notch and the stainless steel spherical bearings placed on the superior, middle and inferior points on the tragus and the ala of the nose i.e., the Campers line S, Campers line M, Campers line I. The angles between the three Camper’s line and the HIP were measured and recorded. Higher mean angulation was recorded in Campers line S –HIP (8.03) followed by Campers line M-HIP (4.60). Campers line I-HIP recorded the least angulation (3.80). The HIP is parallel to the Camper’s plane. The Camper’s plane formed with the posterior reference point as inferior point of the tragus is relatively parallel to the HIP.  相似文献   
89.
Hydroxycitric acid (HCA), a major active ingredient of Garcinia cambogia extracts, is known to suppress body weight gain and fat synthesis in animals and humans. But the underlying mechanism of HCA action is not fully understood. Clinical study on 100 obese individuals for a period of 3 months was performed followed by a computational study aimed to investigate the effects of HCA treatment on human subjects at anthropometric and plasma lipid profile levels. A detailed hepatic metabolic model was used to incorporate the effect of HCA at the metabolic pathway level. Perturbation analysis of ATP citrate lyase activity in the metabolic pathway was performed to simulate the net effect of HCA. Significant reductions in body weight, triceps, subscapular, and mid axillary measurements as well as in serum triglyceride, cholesterol, HDL and LDL levels were observed following HCA dosage. During the study, half of the subjects experienced a decline in body weight and the remainder experienced an increase in body weight. However, analysis of fat mass with the help of empirical correlations clearly showed significant reduction in the mean values due to HCA dosage in both cases. An extra increase in fat free mass was responsible for offsetting the decrease in fat mass for the subjects who experienced an increase in body weight during the trials. Perturbation analysis showed a net reduction in fatty acid, triglyceride and cholesterol synthesis along with urea cycle fluxes under lipogenetic conditions. Moreover, protein synthesis fluxes increased under these conditions. These results indicate that HCA treatment can reduce body weight gain and fat accumulation in obese subjects along with improving their anthropometric parameters and metabolic state.

Hydroxycitric acid (HCA), a major active ingredient of Garcinia cambogia extracts, is known to suppress body weight gain and fat synthesis in animals and humans.  相似文献   
90.
Medicinal chemistry optimization of a previously described stilbene inhibitor of HIV-1, 5350150 (2-(2-(5-nitro-2-thienyl)vinyl)quinoline), led to the identification of the thiazole-5-carboxamide derivative (GPS491), which retained potent anti-HIV-1 activity with reduced toxicity. In this report, we demonstrate that the block of HIV-1 replication by GPS491 is accompanied by a drastic inhibition of viral gene expression (IC50 ~ 0.25 µM), and alterations in the production of unspliced, singly spliced, and multiply spliced HIV-1 RNAs. GPS491 also inhibited the replication of adenovirus and multiple coronaviruses. Low µM doses of GPS491 reduced adenovirus infectious yield ~1000 fold, altered virus early gene expression/viral E1A RNA processing, blocked viral DNA amplification, and inhibited late (hexon) gene expression. Loss of replication of multiple coronaviruses (229E, OC43, SARS-CoV2) upon GPS491 addition was associated with the inhibition of viral structural protein expression and the formation of virus particles. Consistent with the observed changes in viral RNA processing, GPS491 treatment induced selective alterations in the accumulation/phosphorylation/function of splicing regulatory SR proteins. Our study establishes that a compound that impacts the activity of cellular factors involved in RNA processing can prevent the replication of several viruses with minimal effect on cell viability.  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