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   3857篇
  免费   187篇
  国内免费   53篇
耳鼻咽喉   45篇
儿科学   101篇
妇产科学   73篇
基础医学   360篇
口腔科学   115篇
临床医学   291篇
内科学   943篇
皮肤病学   51篇
神经病学   440篇
特种医学   160篇
外科学   895篇
综合类   3篇
预防医学   104篇
眼科学   105篇
药学   142篇
中国医学   2篇
肿瘤学   267篇
  2024年   6篇
  2023年   40篇
  2022年   108篇
  2021年   192篇
  2020年   105篇
  2019年   121篇
  2018年   149篇
  2017年   98篇
  2016年   130篇
  2015年   144篇
  2014年   185篇
  2013年   246篇
  2012年   308篇
  2011年   314篇
  2010年   184篇
  2009年   172篇
  2008年   201篇
  2007年   213篇
  2006年   199篇
  2005年   156篇
  2004年   168篇
  2003年   139篇
  2002年   150篇
  2001年   38篇
  2000年   21篇
  1999年   27篇
  1998年   24篇
  1997年   20篇
  1996年   10篇
  1995年   14篇
  1994年   9篇
  1993年   13篇
  1992年   11篇
  1991年   16篇
  1990年   16篇
  1989年   7篇
  1988年   13篇
  1987年   11篇
  1986年   9篇
  1985年   17篇
  1984年   8篇
  1983年   7篇
  1982年   9篇
  1981年   8篇
  1974年   4篇
  1971年   6篇
  1970年   4篇
  1969年   9篇
  1968年   5篇
  1966年   5篇
排序方式: 共有4097条查询结果,搜索用时 11 毫秒
991.
A total of 137 patients with a diagnosis of chronic bacterial prostatitis (CBP) were subjected to combination pharmacological therapy with antibacterial agents (ciprofloxacin/azithromycin), alpha-blockers (alfuzosin) and Serenoa repens extracts. Of those, 88 patients (64.2%) showed microbiological eradication at the completion of a 6-week cycle of therapy. Of the remaining 49 patients showing persistence of the causative organism(s) or reinfection at the end of treatment, 36 completed a second cycle of combination therapy for 6 weeks: 27 patients (75%) showed eradication of the causative organism, whereas in nine cases persistence or reinfection was observed. The cumulative eradication rate of the present study - calculated on a total of 137 enrolled patients - is 83.9%. Clinical examination showed a marked improvement of signs and symptoms linked to prostatitis. Remarkably, combination therapy could attenuate CBP symptoms prior to microbiological eradication, thus rapidly decreasing the impact of the disease on the quality of life of patients. Clinical remission was extended throughout a follow-up period of 30 months for 94% of patients, whereas seven patients showed relapse of the disease. In summary, our results indicate that about 20% of patients enrolled in this study, who were refractory to a protocol of 6-week combination therapy, could be 'rescued' by a second cycle of treatment. Clinical follow-up data show that combination therapy could ensure extended relief from CBP symptoms, and a general improvement in quality of life.  相似文献   
992.
Cryptorchidism is a pathological condition defined as the failure of the testis to descend into the scrotum, the location of the cryptorchid testis can be in the inguinal canal or in the prescrotal and abdominal area, sometimes resulting in atrophic seminiferous tubules. The aim of this study was to analyze semen quality of men who underwent orchidopexy for unilateral or bilateral cryptorchidism during childhood. Semen quality was investigated by light microscopy to evaluate sperm concentration and motility. Sperm morphology was performed by transmission electron microscope (TEM), and the data were mathematically elaborated. The presence of Y microdeletions was investigated by polymerase chain reaction. The effect of cryptorchidism on meiosis was explored by fluorescence in situ hybridization (FISH). The incidence of azoospermia was higher in the group with bilateral compared with unilateral cryptorchidism, and semen parameters were better in the unilateral group. Sperm pathologies detected by TEM indicated a severe deterioration of sperm quality in both groups. Necrosis and apoptosis appeared to be the most frequent pathologies, and their values reached statistical significance compared with those from fertile controls. The presence of chromosome Y microdeletions in patients with cryptorchidism and severe spermatogenetic defects is controversial. No microdeletions were found in this study. FISH values indicated that the mean percentage of gonosome disomies and diploidies were generally out of normal range, indicating a severe disturbance of meiotic segregation. The effects induced by cryptorchidism resolved in childhood seem to include a spermatogenetic impairment, leading to recommendation of detailed ultrastructural and chromosomal sperm analyses before undertaking assisted reproductive techniques.  相似文献   
993.
OBJECTIVES: We believe early incontinence after radical retropubic prostatectomy (RRP) is mainly due to the shortening of the sphincter's anatomic and functional length as a result of caudal retraction of the urethral sphincteric complex and disruption of the posterior median fibrous raphe. We illustrate a technique of anatomic and functional reconstruction of the rhabdosphincter (RS) aimed at achieving early continence recovery after RRP. Our modification to the Walsh RRP avoids caudal retraction of the urethrosphincteric complex and reconstructs the posterior fibrous raphe. METHODS: Prior to completion of the vesicourethral anastomosis, the posterior fibrous tissues of the sphincter are joined to the residual Denonvilliers fascia on the posterior bladder wall 1-2 cm cephalad and dorsally to the new bladder neck. The study end point was assessment of early and long-term continence rate. Modified RRP (group 1: 250 patients) was compared with unmodified RRP (historical group 2: 50 patients). A crude comparison of treatment effect was assessed by using Pearson chi-square. Multiple logistic regression was used to assess treatment efficacy at discharge, 1, 3, and 12 mo, while taking into account age, pathologic stage, and Gleason score. Continence was defined as 0-1 pad per day. RESULTS: Patients in group 1 achieved significantly better continence at discharge (62.4% vs. 14.0%), 1 mo (74.0% vs. 30%), and 3 mo of follow-up (85.2% vs. 46%); long-term recovery was similar in the two treatment groups (94% vs. 90%). CONCLUSIONS: The technical modification that we proposed achieved a substantial and significant reduction in time to continence with no adverse effects.  相似文献   
994.
The authors analyse the factors that have conditioned the early development of day-surgery in Italy and enumerate its fields of application. They outline the history of day-surgery and report the results of studies, citing laws, documents, rules and guidelines governing its application in Italy today. They also analyse the reasons why a more widespread use of day-surgery is proving difficult in Italy. They consider the surgeon's liability and briefly report the results of day-surgery activity at the "G. Martino" Polyclinic Endocrine General Surgery Unit in Messina, consisting in over 3000 operations since 1987. In conclusion, they consider the undoubted advantages of day-surgery for selected operations and stress that it is an effective alternative in comparison with the traditional hospital stay, according to the new philosophy inspiring modern medical care, namely, that of "operating better, in the patient's interest, at lower cost, and quickly".  相似文献   
995.
Objectives:   To identify the variables predictive of contralateral metachronous upper urinary tract transitional cell carcinoma (UUT-TCC) after nephroureterectomy (NFU) for non-metastatic UUT-TCC.
Methods:   Clinical and pathological data of 234 patients who had undergone NFU for UUT-TCC from 1989 to 2005 in three European urological centers were retrospectively collected and analyzed.
Results:   The median follow-up duration for the whole cohort was 34 months. Contralateral metachronous UUT-TCC was detected in 14 patients (6%). Three patients were treated by NFU, while seven patients underwent ureterectomy and reimplantation and four patients were treated by endoscopic resection plus bacillus Calmette–Guérin instillations within the UUT through a nephrostomic tube. On univariate analysis, a prior history of bladder TCC before NFU was the only factor predictive of the occurrence of contralateral UUT-TCC. Specifically, the 5-year probabilities of being free from contralateral UUT-TCC were 96.6% for the patients with de novo UUT-TCC, and 91.1% and 55.3% for those having non-muscle-invasive and muscle invasive bladder TCC before the UUT cancer, respectively. All survival differences were statistically significant (no history of bladder TCC vs history of non-muscle-invasive bladder TCC, log rank P value 0.015; history of non-muscle-invasive bladder TCC vs history of muscle-invasive bladder TCC, log rank P value 0.035).
Conclusions:   In our multicenter dataset of patients who had undergone NFU for UUT-TCC, contralateral metachronous UUT-TCC occurred in 6% of the patients. A prior history of bladder TCC before NFU was the only variable predictive of UUT recurrence at univariate analysis.  相似文献   
996.
To investigate the role of erythropoietin (EPO) as genetic determinant in the susceptibility to sporadic amyotrophic lateral sclerosis (SALS). We sequenced a 259-bp region spanning the 3'hypoxia-responsive element of the EPO gene in 222 Italian SALS patients and 204 healthy subjects, matched for age and ethnic origin. No potentially causative variation was detected in SALS subjects; in addition, two polymorphic variants (namely C3434T and G3544T) showed the same genotype and haplotype frequencies in patients and controls. Conversely, a weak but significant association between G3544T and age of disease onset was observed (p=0.04). Overall, our data argue against the hypothesis of EPO as a genetic risk factor for motor neuron dysfunction, at least in Italian population. However, further studies on larger cohort of patients are needed to confirm the evidence of EPO gene as modifier factor.  相似文献   
997.
998.
The subventricular zone (SVZ) is a region that lies immediately beneath the ependymal layer on the lateral wall of the lateral ventricles, and is separated from the caudate nucleus by a layer of myelin. It contains multipotent neural stem cells. The aim of this study was to investigate the tissue around the SVZ, with the hypothesis that multimodal MRI is able to highlight the progressive disruption of tissue caused by the neurodegenerative disease in this area. We combined volumetric and diffusion tensor (DTI) imaging using a 3 T imager in a cross-sectional study including 30 patients with amnestic-mild cognitive impairment (a-MCI), 30 patients with Alzheimer's disease (AD) and 30 age- and gender-matched healthy controls (HC). Our data indicate that mean diffusivity (MD) values increase continuously from HC through a-MCI to AD in the bilateral SVZ, where most of the proliferating stem cells in the adult brain are located. This result was specific for the SVZ and could not be observed in other periventricular areas. Multimodal MRI, being able to highlight structural changes of microscopic tissue in humans in vivo, could represent a precious tool to complement histological studies of neurogenesis.  相似文献   
999.
1000.
Tumour are characterised by a high content of cholesteryl esters (CEs) stored in lipid droplets purported to be due to a high rate of intracellular esterification of cholesterol. To verify whether and which pathways involved in CE accumulation are essential in tumour proliferation, the effect of CE deprivation, from both exogenous and endogenous sources, on CEM-CCRF cells was investigated. Cholesterol synthesis, esterification and content, low-density lipoprotein (LDL) binding and high-density lipoprotein (HDL)-CE uptake were evaluated in cultured in both conventional and delipidated bovine serum with or without oleic or linoleic acids, cholesteryl oleate, LDL and HDL. High content of CEs in lipid droplets in this cell line was due to esterification of both newly synthesised cholesterol and that obtained from hydrolysis of LDL; moreover, a significant amount of CE was derived from HDL-CE uptake. Cell proliferation was slightly affected by either acute or chronic treatment up to 400 μM with Sz-58035, an acyl-cholesteryl cholesterol esterification inhibitor (ACAT); although when the enzyme activity was continuously inhibited, CE content in lipid droplets was significantly higher than those in control cells. In these cells, analysis of intracellular and medium CEs revealed a profile reflecting the characteristics of bovine serum, suggesting a plasma origin of CE molecules. Cell proliferation arrest in delipidated medium was almost completely prevented in the first 72 h by LDL or HDL, although in subsequent cultures with LDL, it manifested an increasing mortality rate. This study suggests that high content of CEs in CEM-CCRF is mainly derived from plasma lipoproteins and that part of CEs stored in lipid droplets are obtained after being taken up from HDL. This route appears to be up-regulated according to cell requirements and involved in low levels of c-HDL during cancer. Moreover, the dependence of tumour cells on a source of lipoprotein provides a novel impetus in developing therapeutic strategies for use in the treatment of some tumours.  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