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   626篇
  免费   66篇
  国内免费   3篇
耳鼻咽喉   1篇
儿科学   14篇
妇产科学   8篇
基础医学   110篇
口腔科学   9篇
临床医学   62篇
内科学   125篇
皮肤病学   30篇
神经病学   90篇
特种医学   14篇
外科学   61篇
综合类   1篇
预防医学   49篇
眼科学   9篇
药学   51篇
中国医学   5篇
肿瘤学   56篇
  2023年   14篇
  2022年   20篇
  2021年   34篇
  2020年   22篇
  2019年   29篇
  2018年   32篇
  2017年   30篇
  2016年   38篇
  2015年   26篇
  2014年   29篇
  2013年   29篇
  2012年   42篇
  2011年   37篇
  2010年   24篇
  2009年   18篇
  2008年   29篇
  2007年   23篇
  2006年   28篇
  2005年   18篇
  2004年   15篇
  2003年   23篇
  2002年   24篇
  2001年   10篇
  2000年   4篇
  1999年   4篇
  1998年   3篇
  1997年   5篇
  1996年   4篇
  1995年   2篇
  1994年   4篇
  1993年   4篇
  1992年   5篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1986年   2篇
  1984年   3篇
  1983年   2篇
  1982年   2篇
  1980年   2篇
  1970年   2篇
  1964年   3篇
  1948年   2篇
  1937年   3篇
  1936年   2篇
  1934年   3篇
  1925年   2篇
  1923年   2篇
  1922年   2篇
排序方式: 共有695条查询结果,搜索用时 921 毫秒
31.
32.
33.

Background

The long-term effects of bariatric surgery have yet to be established, and a number of important studies have recently emerged. This systematic review aimed to assess the effects of bariatric surgery on all-cause mortality, cardiovascular events, and cancer compared to non-surgical treatment.

Methods

We searched PubMed, EMBASE, and CENTRAL up to July 13, 2015, and included randomized controlled trials (RCTs) and non-randomized controlled studies comparing bariatric surgery versus non-surgical treatment and reporting data on the three defined outcomes at 1 year or longer. We analyzed RCTs and non-randomized controlled studies, respectively.

Results

Eleven RCTs, 4 non-randomized controlled trials, and 17 cohort studies were included. The randomized evidence suggested substantial uncertainty regarding the effects on all-cause mortality (0/382 vs. 1/287; 7 studies), cancer (OR 0.77, 95 % CI 0.22 to 2.71; 4 studies), and cardiovascular events (no data). The pooled adjusted estimates from non-randomized studies suggested that, compared to the control, the surgical group had lower risk of all-cause mortality (OR 0.55, 95 % CI 0.46 to 0.65; 10 studies), cancer (OR 0.74, 95 % CI 0.65 to 0.85; 2 studies), and cardiovascular events (MI: OR 0.71, 95 % CI 0.54 to 0.94; stroke: OR 0.66, 95 % CI 0.49 to 0.89; and their composite: OR 0.67, 95 % CI 0.54 to 0.83; 1 study).

Conclusions

In conclusion, bariatric surgery could reduce all-cause mortality and probably reduce the risk of any type of cancer. The inference was, however, based on studies with limited methodological rigor. Uncertainty remains regarding the effects on cardiovascular events.
  相似文献   
34.
Time-related trends in the incidence of non-Hodgkin''s lymphoma (NHL) in Denmark were analysed for the period 1943-89. A total of 13 822 patients (7565 men and 6257 women) were included in the study. In men, world-standardised incidence rates per 100 000 population increased from 2.5 in 1943-47 to 9.3 in 1988-89. In women, a similar increase was seen, i.e. from 1.9 in 1943-47 to 6.5 per 100 000 population in 1988-89. For all birth cohorts, the male-to-female incidence ratio was highest among young subjects and fell significantly after the age of 29 years. Trends in age-specific incidence were analysed separately for two periods, i.e. 1943-77 and 1978-89, reflecting an early, pre-AIDS period and a later period possibly influenced by AIDS. In both periods, the incidence of NHL increased in all age groups. However, in recent years a noticeable increase in incidence averaging 8% annually was observed in men and women aged 40-49 years. A number of factors including changes in the perception of NHL and in the diagnostic methods available are considered insufficient to explain the observed increase. The remarkable and parallel time trends observed in young men and women in recent years indicate that factors other than AIDS must be considered.  相似文献   
35.
BACKGROUND AND OBJECTIVE: Automated database studies have become a cornerstone of drug safety assessment. To assess the reliability of automated data, we compared the hospitalisation and mortality rates among three similar studies of automated healthcare databases in North America. METHODS: Similar protocols were used to identify patients diagnosed with chronic obstructive pulmonary disease (COPD) who were treated with inhaled bronchodilators or inhaled corticosteroids in the Saskatchewan Health Database (SHD), the Kaiser Permanente Medical Care Program (KPMCP) of Northern California, and a proprietary automated insurance claims database available from i3 (formerly Ingenix). Automated data were used to compute incidence rates of total hospitalisation, cardiovascular (CV) hospitalisation and hospitalisation due to several specific types of CV outcomes. Record linkage with registries of vital statistics was used to identify deaths, obtain death certificates, and compute rates of total mortality, CV mortality and deaths due to certain CV outcomes. We compared rates in the i3 population with rates in the other two populations using age-adjusted rate ratio estimates and 95% CIs. RESULTS: The i3 cohort had approximately one-half the rates of total mortality, CV mortality and total hospitalisations, but twice the rate of CV hospitalisations, compared with each of the other two database cohorts. DISCUSSION: The unexpectedly higher rates of CV hospitalisations in the i3 population are inconsistent with its lower CV mortality, total mortality and total hospitalisation rates. This discrepancy is not readily explained by a higher prevalence of CV disease or procedures, random variation or confounding. Instead, high CV hospitalisation rates in the i3 population are consistent with a high rate of false-positive diagnoses recorded on insurance billing claims. CONCLUSION: These results underscore the importance of ensuring valid endpoints in automated claims databases.  相似文献   
36.
PURPOSE: Because radiotherapy exerts cytotoxic effects via generation of massive oxidative stress, we hypothesized that catalase, manganese superoxide dismutase, myeloperoxidase (MPO), and endothelial nitric oxide synthase (eNOS) genotypes might result in greater risk of radiotoxicity. EXPERIMENTAL DESIGN: Cases (n = 446) were Caucasian women with breast cancer who received radiotherapy following lumpectomy. Genotypes were determined by matrix-assisted laser desorption/ionization time-of-flight. The development of acute reactions (moist desquamation) associated with genotypes was modeled using the Cox proportional hazards model, accounting for cumulative biologically effective radiation dose. RESULTS: Genotypes associated with higher levels of reactive oxygen species (ROS) were not associated with risk of radiotoxicity. However, relationships between overweight/obesity [body mass index (BMI), >25] and radiotoxicity risk seemed to be modified by eNOS and MPO genotypes associated with higher generation of nitric oxide and ROS, respectively. Women with high BMI (>25) and eNOS GG genotypes were at more than a 6-fold increase in risk (hazard ratio, 6.39; 95% confidence interval, 2.53-16.15) compared with those with BMI <25, and for MPO, those with high BMI (>25) and GG genotypes also had greater risk of radiotoxicity (hazard ratio, 3.61; 95% confidence interval, 1.78-7.35) compared with those with BMI <25. Overweight/obesity was not a strong risk factor among women with other eNOS and MPO genotypes. Exploratory analysis using classification and regression trees indicated that total number of risk alleles contributed, in part, to acute toxicity outcomes among a subgroup of women. CONCLUSIONS: Associations between BMI and radiotoxicity risk may be most apparent among women with genotypes related to higher levels of oxidative stress. Regression trees may be useful in future studies to examine the contributions of multiple factors to individual susceptibility to adverse effects of cancer treatment.  相似文献   
37.
38.
The subproject 1.5 "Neurobiology of Suicidal Behavior" is a multicenter study assessing peripheral parameters of the serotonergic, noradrenergic, and dopaminergic transmitter systems. Additionally, stress hormones and the lipid system as well as inhibitory and excitatory amino acids will be investigated. The different parameters are collected in cerebral spinal fluid (CSF), blood, and saliva. Patients with a depressive spectrum disorder with and without a suicide attempt (during the last three weeks) and being medication free for two weeks are included in the study. So far, 103 patients and controls have been recruited. The design and development of this project as well as interconnections with the others subprojects are described. Preliminary results about the stress hormone system and suicidality are presented.  相似文献   
39.
We have determined the pharmacological activity of N-hydroxypyrazole analogues (3a and 4a) of the classical glutamate receptor ligands ibotenic acid and (RS)-2-amino-2-(3-hydroxy-5-methyl-4-isoxazolyl)acetic acid (AMAA), as well as substituted derivatives of these two compounds. The pharmacological profile of 3a is closer to that of thioibotenic acid rather than ibotenic acid, while 4a is a selective N-methyl-D-aspartic acid (NMDA) receptor agonist. Ring substitution of 3a and 4a leads to NMDA receptor antagonists. Whereas efficacy of 3a derivatives at mglu2 receptor decreases from agonism via partial agonism to antagonism with increasing substituent size, substitution abolishes affinity for mglu1 and mglu4 receptors. Ligand- and receptor-based modelling approaches assist in explaining these pharmacological trends among the metabotropic receptors and suggest a mechanism of partial agonism at mglu2 receptor similar to that proposed for the GluR2 glutamate receptor.  相似文献   
40.
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