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   1314543篇
  免费   104225篇
  国内免费   5469篇
耳鼻咽喉   18699篇
儿科学   44654篇
妇产科学   35466篇
基础医学   186287篇
口腔科学   34270篇
临床医学   117062篇
内科学   262829篇
皮肤病学   28557篇
神经病学   102159篇
特种医学   53026篇
外国民族医学   683篇
外科学   199829篇
综合类   34569篇
现状与发展   16篇
一般理论   384篇
预防医学   97856篇
眼科学   29221篇
药学   99287篇
  81篇
中国医学   5142篇
肿瘤学   74160篇
  2019年   10721篇
  2018年   14843篇
  2017年   11448篇
  2016年   12319篇
  2015年   14498篇
  2014年   19738篇
  2013年   28484篇
  2012年   39381篇
  2011年   41864篇
  2010年   25109篇
  2009年   23614篇
  2008年   39055篇
  2007年   41703篇
  2006年   41912篇
  2005年   40950篇
  2004年   39023篇
  2003年   37681篇
  2002年   36780篇
  2001年   64881篇
  2000年   67371篇
  1999年   57200篇
  1998年   15104篇
  1997年   13758篇
  1996年   13994篇
  1995年   13941篇
  1994年   13220篇
  1993年   12018篇
  1992年   44845篇
  1991年   43737篇
  1990年   42471篇
  1989年   40313篇
  1988年   37078篇
  1987年   36412篇
  1986年   33732篇
  1985年   32365篇
  1984年   24166篇
  1983年   20250篇
  1982年   11699篇
  1981年   10650篇
  1979年   21311篇
  1978年   14785篇
  1977年   12489篇
  1976年   11667篇
  1975年   12600篇
  1974年   14643篇
  1973年   14101篇
  1972年   12938篇
  1971年   11714篇
  1970年   11039篇
  1969年   10012篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
21.
PurposeAnaerobic infections are common yet life-threatening. They are being recovered from all sites of the body, including the cardiovascular system. This study was aimed to determine the retrospective analysis on the isolation of anaerobes in cardiovascular samples received for a decade-long duration. It helps in knowing the frequency of isolation of anaerobic causes of cardiovascular infection.MethodsAll cardiovascular samples from the department of Cardio-thoracic vascular surgery from January 2010 to December 2020 were studied.ResultsOf 601 samples received, predominant samples were vegetations and valvular tissues of 258, followed by 98 samples of pericardial tissues, 92 samples of embolus, 90 samples of blood and post-operative collections, and 63 excised aneurysms and vascular grafts. Of the total, 15 samples grew anaerobes where Clostridium species were the predominant isolates. Clostridioides difficile was isolated in 2 samples.ConclusionsAnaerobes in cardiovascular samples are uncommon yet form a significant cause of morbidity and mortality. Most infections are from the contiguous spread, penetrating trauma, and hematogenous causing endocarditis or valvular infections. These conditions and samples form the seat of infectious focus and clinical suspicion towards the anaerobic cause of these conditions, especially in conventional routine culture-negative samples. Timely diagnosis of anaerobic infections plays a vital role in the good prognostic outcome of patients undergoing cardiothoracic and vascular surgery.  相似文献   
22.
Peng  L. Q.  Wu  X. X.  Chen  G.  Cai  H. Z.  Tang  Y. P.  Chen  Q. Y.  Chen  X. Y. 《Bulletin of experimental biology and medicine》2022,173(3):335-340
Bulletin of Experimental Biology and Medicine - This study aimed to explore the effects of Wenyang Zhenshuai granules (WZG) on the morphology of cardiomyocytes, cell viability, and the expression...  相似文献   
23.

Objective

To examine the experience of interracial anxiety among health professionals and how it may affect the quality of their interactions with patients from racially marginalized populations. We explored the influence of prior interracial exposure—specifically through childhood neighborhoods, college student bodies, and friend groups—on interracial anxiety among medical students and residents. We also examined whether levels of interracial anxiety change from medical school through residency.

Data Source

Web-based longitudinal survey data from the Medical Student Cognitive Habits and Growth Evaluation Study.

Study Design

We used a retrospective longitudinal design with four observations for each trainee. The study population consisted of non-Black US medical trainees surveyed in their 1st and 4th years of medical school and 2nd and 3rd years of residency. Mixed effects longitudinal models were used to assess predictors of interracial anxiety and assess changes in interracial anxiety scores over time.

Principal Findings

In total, 3155 non-Black medical trainees were followed for 7 years. Seventy-eight percent grew up in predominantly White neighborhoods. Living in predominantly White neighborhoods and having less racially diverse friends were associated with higher levels of interracial anxiety among medical trainees. Trainees' interracial anxiety scores did not substantially change over time; interracial anxiety was highest in the 1st year of medical school, lowest in the 4th year, and increased slightly during residency.

Conclusions

Neighborhood and friend group composition had independent effects on interracial anxiety, indicating that premedical racial socialization may affect medical trainees' preparedness to interact effectively with diverse patient populations. Additionally, the lack of substantial change in interracial anxiety throughout medical training suggests the importance of providing curricular tools and structure (e.g., instituting interracial cooperative learning activities) to foster the development of healthy interracial relationships.  相似文献   
24.
25.
The 5-year overall survival rate of a patient with unresectable metastatic colorectal cancer is poor at approximately 14%. Similarly, historical data on liver transplantation (LT) in those with colorectal liver metastases (CRLM) showed poor outcomes, with 5-year survival rates between 12% and 21%. More recently, limited data have shown improved outcomes in select patients with 5-year overall survival rates of approximately 60%. Despite these reported survival improvements, there is no significant improvement in disease-free survival. Given the uncertain benefit with this therapeutic approach and a renewed investigational interest, we aimed to conduct a contemporary systematic review on LT for CRLM. A systematic review of the literature was performed according to the preferred reporting items for systematic reviews and meta-analysis statement. English articles reporting on data regarding LT for CRLM were identified through the MEDLINE (via PubMed), Cochrane Library, and ClinicalTrials.gov databases (last search date: December 16th, 2021) by 2 researchers independently. A total of 58 studies (45 published and 13 ongoing) were included. Although early retrospective studies suggest the possibility that some carefully selected patients may benefit from LT, there is minimal prospective data on the topic and LT remains exploratory in the setting of CRLM. Additionally, several other challenges, such as the limited availability of deceased donor organs and defining appropriate selection criteria, remain when considering the implementation of LT for these patients. Further evidence from ongoing prospective trials is needed to determine if and to what extent there is a role for LT in patients with surgically unresectable CRLM.  相似文献   
26.
Maternal and Child Health Journal - To compare the prevalence of highly effective contraceptive use by 12 weeks postpartum among participants of Centering Pregnancy®, a model of group...  相似文献   
27.
28.
29.
目的研究低氧刺激慢性鼻窦炎伴鼻息肉(CRSwNP)与正常鼻黏膜上皮细胞炎性因子的变化与异同,探讨其在CRSwNP发病机制中的作用。方法选择2015年6月至2018年1月在吉林大学中日联谊医院就诊的68例CRSwNP患者,其中男性36例,女性32例,年龄(45.2±12.5)岁(xˉ±s,下同),患者的鼻息肉黏膜纳入慢性鼻窦炎鼻息肉组(CRS-NP组),下鼻甲黏膜纳入慢性鼻窦炎下鼻甲组(CRS-IT组),并根据组织病理学结果进一步分成嗜酸粒细胞浸润及非浸润两种类型,即嗜酸粒细胞浸润性鼻息肉组(Eos-NP组,n=34)、非嗜酸粒细胞浸润性鼻息肉组(Non-Eos-NP组,n=34)、嗜酸粒细胞浸润性鼻息肉患者的下鼻甲组(Eos-IT组,n=20)和非嗜酸粒细胞浸润性鼻息肉患者的下鼻甲组(Non-Eos-IT组,n=20);同期25例鼻窦囊肿或鼻中隔偏曲患者的下鼻甲黏膜作为对照组(n=25),其中男性14例,女性11例,年龄(42.8±10.2)岁。免疫组织化学染色分析各组黏膜上皮组织中白细胞介素(IL)17A、干扰素γ(IFN-γ)、肿瘤坏死因子α(TNF-α)与乏氧诱导因子(hypoxia-inducible factor 1α,HIF-1α)的表达情况。酶联免疫吸附试验检测低氧刺激0、24和48 h后各组原代鼻黏膜上皮细胞分泌IL-17A、IFN-γ和TNF-α的差异;免疫荧光、固态光源高内涵与免疫印记实验检测原代鼻黏膜上皮细胞HIF-1α的表达情况。应用SPSS 17.0软件对数据进行统计学分析,采用双向方差分析作为主要统计学方法。结果免疫组织化学染色结果显示,IL-17A和TNF-α在对照组中表达最高(光密度值分别为0.37±0.03、0.53±0.02),IFN-γ和HIF-1α在Eos-IT组中表达最高(光密度值分别为0.47±0.03、0.39±0.02)。未接受低氧刺激时,IL-17A与TNF-α在对照组中水平较低;低氧刺激48 h后,对照组的IL-17A与TNF-α分泌量明显高于其他各组。未接受低氧刺激时,Eos-NP组分泌的IFN-γ明显高于对照组[(13.7±1.3)pg/ml比(11.1±1.6)pg/ml,P<0.05];低氧刺激48 h后,IFN-γ在对照组和Eos-NP组中的分泌量没有显著区别。对照组与CRS-IT组表达的HIF-1α随低氧时间延长而增加,Eos-NP组与Non-Eos-NP组表达的HIF-1α随低氧时间延长而减少。对照组与CRS-IT组HIF-1α主要表达于鼻黏膜上皮细胞的细胞质内,CRS-NP组HIF-1α主要表达于鼻黏膜上皮细胞的细胞核内。结论低氧刺激下,CRSwNP患者的鼻息肉、下鼻甲与正常鼻黏膜上皮细胞中IL-17A、TNF-α、IFN-γ的分泌以及HIF-1α的表达水平存在差异,且呈现不同的亚细胞定位,提示其可能参与了CRSwNP发病相关基因的转录与调控。  相似文献   
30.
Yue  Wentao  Zhang  Enjie  Liu  Ruixia  Zhang  Yue  Wang  Chengrong  Gao  Shen  Su  Shaofei  Gao  Xiao  Wu  Qingqing  Yang  Xiaokui  Papageorghiou  Aris T.  Yin  Chenghong 《European journal of epidemiology》2022,37(3):295-304
European Journal of Epidemiology - The China birth cohort study (CBCS) is a prospective longitudinal, mega-cohort study and the first national-based birth cohort study, aiming to establish a birth...  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