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   229256篇
  免费   18938篇
  国内免费   4823篇
耳鼻咽喉   3908篇
儿科学   4340篇
妇产科学   3877篇
基础医学   16981篇
口腔科学   8113篇
临床医学   20208篇
内科学   21583篇
皮肤病学   2470篇
神经病学   11010篇
特种医学   6041篇
外国民族医学   11篇
外科学   30727篇
综合类   35391篇
现状与发展   9篇
一般理论   25篇
预防医学   28233篇
眼科学   2398篇
药学   20807篇
  342篇
中国医学   25991篇
肿瘤学   10552篇
  2024年   775篇
  2023年   4233篇
  2022年   7819篇
  2021年   11052篇
  2020年   10433篇
  2019年   12892篇
  2018年   11503篇
  2017年   9577篇
  2016年   8026篇
  2015年   7611篇
  2014年   15157篇
  2013年   15265篇
  2012年   13526篇
  2011年   14485篇
  2010年   11671篇
  2009年   10176篇
  2008年   9456篇
  2007年   9516篇
  2006年   8061篇
  2005年   6801篇
  2004年   5663篇
  2003年   5135篇
  2002年   3984篇
  2001年   3363篇
  2000年   2975篇
  1999年   2455篇
  1998年   1981篇
  1997年   1744篇
  1996年   1387篇
  1995年   1329篇
  1994年   1193篇
  1993年   1043篇
  1992年   939篇
  1991年   857篇
  1990年   752篇
  1989年   741篇
  1988年   682篇
  1987年   624篇
  1985年   2169篇
  1984年   2454篇
  1983年   1591篇
  1982年   2094篇
  1981年   1544篇
  1980年   1386篇
  1979年   1202篇
  1978年   1042篇
  1977年   737篇
  1976年   1022篇
  1975年   761篇
  1974年   646篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
151.
基于调控肠道菌群探讨中药防治脑卒中   总被引:3,自引:3,他引:0  
肠道菌群是一个独特的生态系统,被称为人体"被遗忘的器官",被誉为人类的"第二基因组"。肠道菌群失调与许多中枢神经系统疾病相关,例如帕金森病、阿尔茨海默症、精神分裂症及多发性硬化等。脑卒中具有高的发病率、复发率、死亡率和致残率的特点。肠道菌群在脑卒中的发生、发展中起着关键的作用,可通过影响机体的吸收、代谢、血压、血糖、血脂及动脉粥样斑块等因素,进一步影响脑卒中的发病。中医认为脾胃气血流注失度、阴阳盛衰失衡,机体生理功能失调,化生"风、火、痰、虚、瘀"等病理产物,可致中风的发生。脾胃主腐熟运化水谷,肠道菌群影响饮食的消化吸收,现代研究的肠道菌群功能与中医之脾胃功能失调相关。因此,调整肠道菌群的稳态,可作为一个潜在的干预靶点预防和治疗缺血性脑卒中。中药干预脑卒中已经取得了很好的疗效,是否与调节肠道菌群有关,值得未来做进一步的研究。同时对中药有效成分(小檗碱、黄芩苷、白藜芦醇等),中药单方(丹参、红景天等)和中药组方(补阳还五汤、脑心通胶囊、补中益气汤等)防治脑缺血的研究进展进行综述,为缺血性脑卒中的预防和开发提供新的途径和思路。  相似文献   
152.
153.

Background

Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism.

Methods

A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status.

Results

Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (–0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (–1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients.

Conclusion

Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile.  相似文献   
154.
Our aim was to evaluate the long-term skeletal stability of the mandible in 21 patients after orthognathic surgery with physiological positioning. The measurement points SNB, B point (X, Y), Pog (X, Y), and the angle of the ramus were measured on cephalometric photographs to assess skeletal stability preoperatively, immediately after operation, and one and two years postoperatively. In addition, we evaluated the clinical symptoms of disorders of the temporomandibular joint (TMJ). The analysis of the cephalometric photographs showed that SNB, B point X, and Pog X showed no significant differences among the postoperative time points. On the other hand, B point Y and Pog Y showed no significant differences throughout the study period. We compared the angle of the ramus before operation and two years postoperatively, and no significant difference was found. In addition, no cases showed any pathological symptoms of disorders of the TMJ two years postoperatively. The long-term stability after orthognathic surgery with physiological positioning was confirmed, and it seems to be a reliable orthognathic treatment in patients with mandibular prognathism.  相似文献   
155.
《Australian critical care》2022,35(4):408-414
BackgroundClinically significant post-traumatic stress symptoms (PTSS) have been reported in up to a quarter of paediatric intensive care unit (PICU) survivors. Ongoing PTSS negatively impacts children's psychological development and physical recovery. However, few data regarding associations between potentially modifiable PICU treatment factors, such as analgosedatives and invasive procedures, and children's PTSS have been reported.ObjectivesWe sought to investigate the medical treatment factors associated with children's PTSS after PICU discharge.MethodsA prospective longitudinal cohort study was conducted in two Australian tertiary referral PICUs. Children aged 2-16 y admitted to the PICU between June 2008 and January 2011 for >8 h and <28 d were eligible for participation. Biometric and clinical data were obtained from medical records. Parents reported their child's PTSS using the Trauma Symptom Checklist for Young Children at 1, 3, 6, and 12 months after discharge. Logistic regression was used to assess potential associations between medical treatment and PTSS.ResultsA total of 265 children and their parents participated in the study. In the 12-month period following PICU discharge, 24% of children exhibited clinically elevated PTSS. Median risk of death (Paediatric Index of Mortality 2 [PIM2]) score was significantly higher in the PTSS group (0.31 [IQR 0.14–1.09] v 0.67 [IQR 0.20–1.18]; p = 0.014). Intubation and PICU and hospital length of stay were also significantly associated with PTSS at 1 month, as were midazolam, propofol, and morphine. After controlling for gender, reason for admission, and PIM2 score, only midazolam was significantly and independently associated with PTSS and only at 1 month (adjusted odds ration (aOR) 3.63, 95% CI 1.18, 11.12, p = 0.024). No significant relationship was observed between the use of medications and PTSS after 1 month.ConclusionsElevated PTSS were evident in one quarter (24%) of children during the 12 months after PICU discharge. One month after discharge, elevated PTSS were most likely to occur in children who had received midazolam therapy.  相似文献   
156.
ObjectivesTinnitus can induce disabling psychological suffering, requiring an integrative multimodal approach, combining neuromodulation and psychotherapeutic methods. We sought to evaluate the therapeutic efficacy and acceptability of Eye Movement Desensitization and Reprocessing (EMDR) in tinnitus.Materials and methodsThis was a single-center prospective non-comparative study. Inclusion criteria comprised: adult patient, with chronic tinnitus, Tinnitus Handicap Inventory (THI) score > 17, causing psychological distress motivating active treatment after ineffective “classic” treatment (combining advice, sound therapy and first-line drug treatment), and agreement to EMDR therapy. Therapeutic efficacy was defined by a decrease in THI or Visual Analog Scale (VAS) scores. Treatment acceptability was defined by the rate of included patients who completed therapy.ResultsThirty-eight patients were included. There was a significant reduction of 53.5% in THI score in 78.9% of patients (P < 0.0001; 64.8 ± 20.8 before versus 31.8 ± 24.7 after treatment), and of 51% in VAS score in 76.3% of patients (P < 0.0001; 7.24 ± 2.12 before versus 3.58 ± 2.03 after treatment). The treatment acceptability was 86.8%.ConclusionEMDR appeared to be an effective alternative that was acceptable to the majority of patients, after failure of “classic” first-line treatment, improving quality of life in tinnitus patients and thus relieving disability.  相似文献   
157.
《Value in health》2022,25(12):1958-1966
ObjectivesNational health technology assessments (HTAs) across Europe show differences in evidentiary requirements from assessments by the European Medicines Agency (EMA), affecting time to patient access for drugs after marketing authorization. This article analyzes the differences between EMA and HTA bodies’ evidentiary requirements for oncology drugs and provides recommendations on potential further alignment to minimize and optimally manage the remaining differences.MethodsInterviews were performed with representatives and drug assessment experts from EMA and HTA bodies to identify evidentiary requirements for several subdomains and collect recommendations for potentially more efficiently addressing differences. A comparative analysis of acceptability of the evidence by EMA and the HTA bodies and for potential further alignment between both authorities was conducted.ResultsAcceptability of available evidence was higher for EMA than HTA bodies. HTA bodies and EMA were aligned on evidentiary requirements in most cases. The subdomains showing notable differences concerned the acceptance of limitation of the target population and extrapolation of target populations, progression-free survival and (other) surrogate endpoints as outcomes, cross-over designs, short trial duration, and clinical relevance of the effect size. Recommendations for reducing or optimally managing differences included joint early dialogues, joint relative effectiveness assessments, and the use of managed entry agreements.ConclusionsDifferences between assessments of EMA and HTA bodies were identified in important areas of evidentiary requirements. Increased alignment between EMA and HTA bodies is suggested and recommendations for realization are discussed.  相似文献   
158.
Genetic and epigenetic alterations importantly contribute to the pathogenesis of lung cancer. In the study, we measured the frequency and distribution of molecular abnormalities of EGFR as well as the aberrant promoter methylations of BRCA1, MGMT, MLH1, and RASSF1A in Vietnamese lung adenocarcinomas. We investigated the association between genetic and epigenetic alteration, and between each abnormality with clinicopathologic parameters. Somatic EGFR mutation that was found in 49/139 (35.3%) lung adenocarcinomas showed a significant association with young age, female gender, and non-smokers. EGFR overexpression was identified in 82 tumors (59.0%) and statistical relationships with EGFR or BRCA1 methylation but not EGFR mutation. In addition, EGFR, BRCA1, MGMT, MLH1, and RASSF1A methylations were found in 33 (23.7%), 41 (29.5%), 46 (33.1%), 28 (20.1%), and 41 (29.5%) cases of a total of 139 lung adenocarcinomas, respectively. The RASSF1A methylation was found to be linked to the smoking habit. Methylations in MGMT and RASSF1A were also found to correlate with metastasis status. Furthermore, the distribution of EGFR mutation and that of BRCA1, MGMT or RASSF1A methylation were significantly exclusive in lung adenocarcinomas. The main finding of our study demonstrate that epigenetic abnormalities might play a critical role for the lung tumorigenesis in patients with smoking history and metastasis, and partly affect the predictive value of EGFR mutations through blocking expression due to promoter EGFR hypermethylation. Mutually exclusive distribution of genetic and epigenetic alterations reflects differently biological characteristics in the etiology of lung adenocarcinomas.  相似文献   
159.
160.
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