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   1762篇
  免费   81篇
  国内免费   31篇
耳鼻咽喉   17篇
儿科学   12篇
妇产科学   28篇
基础医学   217篇
口腔科学   26篇
临床医学   155篇
内科学   466篇
皮肤病学   86篇
神经病学   124篇
特种医学   56篇
外科学   251篇
综合类   6篇
预防医学   73篇
眼科学   48篇
药学   130篇
中国医学   5篇
肿瘤学   174篇
  2023年   8篇
  2022年   18篇
  2021年   36篇
  2020年   26篇
  2019年   23篇
  2018年   42篇
  2017年   31篇
  2016年   51篇
  2015年   58篇
  2014年   50篇
  2013年   97篇
  2012年   146篇
  2011年   117篇
  2010年   75篇
  2009年   62篇
  2008年   130篇
  2007年   132篇
  2006年   149篇
  2005年   127篇
  2004年   100篇
  2003年   104篇
  2002年   95篇
  2001年   12篇
  2000年   3篇
  1999年   8篇
  1998年   20篇
  1997年   12篇
  1996年   16篇
  1995年   15篇
  1994年   16篇
  1993年   5篇
  1992年   13篇
  1991年   3篇
  1990年   5篇
  1989年   7篇
  1988年   7篇
  1987年   6篇
  1986年   4篇
  1985年   8篇
  1984年   7篇
  1983年   4篇
  1982年   5篇
  1981年   5篇
  1980年   3篇
  1977年   2篇
  1938年   1篇
  1936年   1篇
  1912年   1篇
  1909年   2篇
  1908年   1篇
排序方式: 共有1874条查询结果,搜索用时 15 毫秒
11.
BackgroundLymphatic disorders (LDs) are the most common minor complications after kidney transplantation (KT), with an incidence rate between 0.6% and 33.9%, which appears to be related to both surgical and medical factors. LDs mostly resolve spontaneously, but occasionally a surgical approach may be required.Materials and MethodsWe report our experience with 7 KT recipients who developed persistent lymphorrhea (>150 mL/24 h) between October 2017 and March 2019. All cases were treated as outpatients with parietal fistulectomy (PF). The fibrotic aponeurotic-cutaneous tract was thoroughly excised, and the residual aponeurotic defect was closed by watertight suturing. Serial abdominal ultrasounds (US) were carried out after the procedure.ResultsA small perirenal graft lymphocele of <2 cm was detected by US in all patients after 48 to 72 hours, without any evidence of either vascular or ureteral compression. During the subsequent scheduled US follow-up, lymphoceles did not increase in size, and additional interventions were not needed. Neither superficial nor deep surgical-site infections were recorded in such patients.ConclusionsPF was found to be a safe and effective minimally invasive approach for persistent lymphorrhea after KT. It could be easily performed with local anesthesia in a day surgery setting and did not require patient hospitalization.  相似文献   
12.
We have analysed the [AGC] expansion in leucocytes, muscle and sperm from 17 individuals affected by myotonic dystrophy (DM). Skeletal muscle showed a larger repeat number than leucocytes in the same patient. A similar degree of expansion was detected in differently affected muscles of a single patient. The germline mutation ( 350 repeats) was expanded in somatic cells of the progeny in all patients examined. Our results provide evidence of an early postzygotic instability of the [AGC] repeat in DM.  相似文献   
13.
14.
Emerging aspects of pharmacotherapy for obesity and metabolic syndrome.   总被引:2,自引:0,他引:2  
Obesity is a multifactorial, chronic disorder that has reached epidemic proportions in most industrialized countries and is threatening to become a global epidemic. Obese patients are at higher risk from coronary artery disease, hypertension, hyperlipidemia, diabetes mellitus, cancers, cerebrovascular accidents, osteoarthritis, restrictive pulmonary disease, and sleep apnoea. In particular, visceral fat accumulation is usually accompanied by insulin resistance or type 2 diabetes mellitus, hypertension, hypertriglyceridemia, high uremic acid levels, low high density lipoprotein (HDL) cholesterol to define a variously named syndrome or metabolic syndrome. Metabolic syndrome is now considered a major cardiovascular risk factor in a large percentage of population in worldwide. Both obesity and metabolic syndrome are particularly challenging clinical conditions to treat because of their complex pathophysiological basis. Indeed, body weight represents the integration of many biological and environmental components and relationships among fat and glucose tolerance or blood pressure are not completely understood. Efforts to develop innovative anti-obesity drugs, with benefits for metabolic syndrome, have been recently intensified. In general two distinct strategies can be adopted: first, to reduce energy intake; second, to increase energy expenditure. Here we review some among the most promising avenues in these two fields of drug therapy of obesity and, consequently, of metabolic syndrome.  相似文献   
15.
Cyanobacteria are ubiquitous photosynthetic micro-organisms forming blooms and scums in surface water; among them some species can produce cyanotoxins giving rise to some concern for human health and animal life. To date, more than 65 cyanobacterial neurotoxins have been described, of which the most studied are the groups of anatoxins and saxitoxins (STXs), comprising many different variants. In freshwaters, the hepatotoxic microcystins represent the most frequently detected cyanotoxin: on this basis, it could appear that neurotoxins are less relevant, but the low frequency of detection may partially reflect an a priori choice of target analytes, the low method sensitivity and the lack of certified standards. Cyanobacterial neurotoxins target cholinergic synapses or voltage-gated ion channels, blocking skeletal and respiratory muscles, thus leading to death by respiratory failure. This review reports and analyzes the available literature data on environmental occurrence of cyanobacterial neurotoxic alkaloids, namely anatoxins and STXs, their biosynthesis, toxicology and epidemiology, derivation of guidance values and action limits. These data are used as the basis to assess the risk posed to human health, identify critical exposure scenarios and highlight the major data gaps and research needs.  相似文献   
16.

BACKGROUND:

To quantify the magnitude of benefit of the addition of hormone treatment (HT) to exclusive radiotherapy for locally advanced prostate cancer, a literature‐based meta‐analysis was conducted.

METHODS:

Event‐based relative risks (RR) with 95% confidence intervals (CIs) were derived through a random‐effect model. Differences in primary (biochemical failure and clinical progression‐free survival) and secondary outcomes (cancer‐specific survival, overall survival [OS], recurrence patterns, and toxicity) were explored. Absolute differences and numbers of patients needed to treat (NNT) were calculated. A heterogeneity test, a metaregression analysis with clinical predictors of outcome, and a correlation analysis for surrogate endpoints were also performed.

RESULTS:

Seven trials (4387 patients) were gathered. Hormone suppression significantly decreased both biochemical failure (RR, 0.76; 95% CI, 0.70‐0.82; P < .0001) and clinical progression‐free survival (RR, 0.81; 95% CI 0.71‐0.93; P = .002), with absolute differences of 10% and 7.7%, respectively, which translates into 10 and 13 NNT. cancer‐specific survival (RR, 0.76; 95% CI, 0.69‐0.83; P < .0001) and OS (RR, 0.86; 95% CI, 0.80‐0.93; P < .0001) were also significantly improved by the addition of HT, without significant heterogeneity, with absolute differences of 5.5% and 4.9%, respectively, which translates into 18 and 20 NNT. Local and distant relapse were significantly decreased by HT, by 36% and 28%, respectively, and no significant differences in toxicity were found. Primary and secondary efficacy outcomes were significantly correlated.

CONCLUSIONS:

Hormone suppression plus radiotherapy significantly decreases recurrence and mortality of patients with localized prostate cancer, without affecting toxicity. Cancer 2009. © 2009 American Cancer Society.  相似文献   
17.
Sarcoidosis is thought to result from the interaction between an unknown environmental antigenic trigger and the host's genetic susceptibility. We hypothesized that sarcoidosis, or one of the disease subsets, could be associated with single nucleotide polymorphisms of C-C chemokine receptor 2 (CCR2) gene. Eight single-nucleotide polymorphisms in CCR2 were studied in a total of 304 Dutch individuals (90 non-L?fgren sarcoidosis, 47 L?fgren's syndrome, 167 control subjects). From the investigated CCR2 polymorphisms, nine haplotypes were deduced (haplotypes 1-9). In patients with L?fgren's syndrome, a strongly significant increase in the frequency of CCR2-haplotype 2, which includes four unique alleles (A at nucleotide position -6752, A at 3,000, T at 3,547, and T at 4,385), was observed compared with control subjects (74% vs. 38% respectively, p < 0.0001), whereas no difference was found between non-L?fgren sarcoidosis and control subjects (both 38%). The association between CCR2-haplotype 2 carriage frequency and L?fgren's syndrome (odds ratio, 4.4; p < 0.0001) remained significant after adjustment for human leukocyte antigen haplotype DRB1*0301-DQB1*0201 (odds ratio, 11.5; p < 0.0001) and female sex (odds ratio, 3.2; p = 0.003), two known risk factors for L?fgren's syndrome. In conclusion, this report describes a strong association between CCR2-haplotype 2 and L?fgren's syndrome. Further studies are needed to understand the molecular mechanisms underlying this association.  相似文献   
18.
We study the thermodynamic and dynamic behaviors of twist-induced denaturation bubbles in a long, stretched random sequence of DNA. The small bubbles associated with weak twist are delocalized. Above a threshold torque, the bubbles of several tens of bases or larger become preferentially localized to AT-rich segments. In the localized regime, the bubbles exhibit "aging" and move around subdiffusively with continuously varying dynamic exponents. These properties are derived by using results of large-deviation theory together with scaling arguments and are verified by Monte Carlo simulations.  相似文献   
19.
20.
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