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   5943篇
  免费   405篇
  国内免费   125篇
耳鼻咽喉   55篇
儿科学   111篇
妇产科学   80篇
基础医学   810篇
口腔科学   250篇
临床医学   499篇
内科学   772篇
皮肤病学   74篇
神经病学   665篇
特种医学   190篇
外科学   513篇
综合类   620篇
预防医学   590篇
眼科学   126篇
药学   635篇
中国医学   277篇
肿瘤学   206篇
  2023年   113篇
  2022年   155篇
  2021年   263篇
  2020年   185篇
  2019年   186篇
  2018年   195篇
  2017年   173篇
  2016年   184篇
  2015年   161篇
  2014年   334篇
  2013年   405篇
  2012年   344篇
  2011年   327篇
  2010年   248篇
  2009年   274篇
  2008年   261篇
  2007年   242篇
  2006年   222篇
  2005年   167篇
  2004年   165篇
  2003年   157篇
  2002年   104篇
  2001年   118篇
  2000年   87篇
  1999年   93篇
  1998年   88篇
  1997年   85篇
  1996年   55篇
  1995年   57篇
  1994年   50篇
  1993年   69篇
  1992年   67篇
  1991年   52篇
  1990年   70篇
  1989年   59篇
  1988年   63篇
  1987年   42篇
  1986年   38篇
  1985年   76篇
  1984年   68篇
  1983年   38篇
  1982年   52篇
  1981年   58篇
  1980年   49篇
  1979年   35篇
  1978年   32篇
  1977年   22篇
  1976年   31篇
  1975年   15篇
  1974年   8篇
排序方式: 共有6473条查询结果,搜索用时 15 毫秒
1.
PurposeAccording to the social determinants of health framework, income inequality is a potential risk factor for adverse mental health. However, few studies have explored the mechanisms suspected to mediate this relationship. The current study addresses this gap through a mediation analysis to determine if social support and community engagement act as mediators linking neighbourhood income inequality to maternal anxiety and depressive symptoms within a cohort of new mothers living in the City of Calgary, Canada.MethodsData collected at three years postpartum from mothers belonging to the All Our Families (AOF) cohort were used in the current study. Maternal data were collected between 2012 and 2015 and linked to neighbourhood socioeconomic data from the 2006 Canadian Census. Income inequality was measured using Gini coefficients derived from 2006 after-tax census data. Generalized structural equation models were used to quantify the associations between income inequality and mental health symptoms, and to assess the potential direct and indirect mediating effects of maternal social support and community engagement.ResultsIncome inequality was not significantly associated with higher depressive symptoms (β = 0.32, 95%CI = −0.067, 0.70), anxiety symptoms (β = 0.11, 95%CI = −0.39, 0.60), or lower social support. Income inequality was not associated with community engagement. For the depression models, higher social support was significantly associated with lower depressive symptoms (β = −0.13, 95%CI = −0.15, −0.097), while community engagement was not significantly associated with depressive symptoms (β = 0.059, 95%CI = −0.15, 0.27). Similarly, for the anxiety models, lower anxiety symptoms were significantly associated with higher levels of social support (β = −0.17, 95%CI = −0.20, −0.13) but not with higher levels of community engagement (β = 0.14, 95%CI = −0.14, 0.41).ConclusionThe current study did not find clear evidence for social support or community engagement mediating the relationship between neighbourhood income inequality and maternal mental health. Future investigations should employ a broader longitudinal approach to capture changes in income inequality, potential mediators, and mental health symptomatology over time.  相似文献   
2.
《Seminars in Arthroplasty》2015,26(2):108-111
Bone loss is commonly encountered during revision total knee arthroplasty (TKA). Small defects can be adequately managed with cement filling (with or without screws), modular prosthetic augments, and morselized allograft. For larger defects, cancellous impaction grafting and structural allografts have traditionally been utilized. More recently, highly porous tantalum cones and titanium sleeves have been designed to achieve axial and rotational stability in the metaphysis and subsequent biologic fixation. Sleeves are linked to one type of prosthesis, whereas cones are unlinked and can be used with any implant design. Multiple studies have demonstrated excellent survivorship and radiographic osseointegration at mid-term follow-up. This article provides a review of contemporary methods of bone loss management with a focus on highly porous metals and an emphasis on the authors’ preferred method for managing the severe bone loss in revision TKA.  相似文献   
3.
目的:对比不同矫治器对错[牙合]畸形患者面高度及前后牙咬合关系的影响。方法:选取于笔者医院接受矫治的83例错[牙合]畸形患者,根据患者矫治器类型分为直丝弓组和Begg组,分别为42例和41例。比较并分析两组患者治疗前后牙咬合关系、硬组织、磨牙及面高度的变化情况。结果:矫治后,两组患者OJ-PPV、OB-PP、LMA-MPV、LMA-MPV均降低,Begg矫治组OJ-PPV水平显著高于直丝弓矫治组,OB-PP、LMA-MPV、LMA-MPV水平显著低于直丝弓矫治组,差异均具有统计学意义(P<0.05);两组患者LAFH、LAFH/TAFH、PFH/TAFH水平均升高,其中Begg矫治组患者LAFH水平显著低于直丝弓矫治组,差异均具有统计学意义(P<0.05);两组患者LMA-MP、LMC-MP水平均升高,差异具有统计学意义(P<0.05);矫治前后,两组患者SNA、SNA、ANB水平均无统计学差异(P>0.05)。结论:两种矫治器对错[牙合]畸形患者硬组织变化均无明显影响,其中Begg矫治对患者前后牙咬合关系改善作用更强,直丝弓对患者面高度的改善能力更强。  相似文献   
4.
5.
Cerebral Palsy motor disorder triggers orthopedic complications. These complications do develop by themselves and gradually degrade the motor function. The functioning of the ventilatory pump is no exception to this process. Other orthopedic impairments are impacting more indirectly ventilation. Some orthopedic treatments used for PC people are likely to worsen this clinical situation, temporarily or more permanently. Any therapeutic intervention must include two essential points: acting previously to realign posture and considering interactions of treatments on different functions.  相似文献   
6.
Background & Aims: Impaired message-structure mapping results in deficits in both sentence production and comprehension in aphasia. Structural priming has been shown to facilitate syntactic production for persons with aphasia (PWA). However, it remains unknown if structural priming is also effective in sentence comprehension. We examined if PWA show preserved and lasting structural priming effects during interpretation of syntactically ambiguous sentences and if the priming effects occur independently of or in conjunction with lexical (verb) information.

Methods & Procedures: Eighteen PWA and 20 healthy older adults (HOA) completed a written sentence-picture matching task involving the interpretation of prepositional phrases (PP; the chef is poking the solider with an umbrella) that were ambiguous between high (verb modifier) and low attachment (object noun modifier). Only one interpretation was possible for prime sentences, while both interpretations were possible for target sentences. In Experiment 1, the target was presented immediately after the prime (0-lag). In Experiment 2, two filler items intervened between the prime and the target (2-lag). Within each experiment, the verb was repeated for half of the prime-target pairs, while different verbs were used for the other half. Participants’ off-line picture matching choices and response times were measured.

Results: After reading a prime sentence with a particular interpretation, HOA and PWA tended to interpret an ambiguous PP in a target sentence in the same way and with faster response times. Importantly, both groups continued to show this priming effect over a lag (Experiment 2), although the effect was not as reliable in response times. However, neither group showed lexical (verb-specific) boost on priming, deviating from robust lexical boost seen in the young adults of prior studies.

Conclusions: PWA demonstrate abstract (lexically-independent) structural priming in the absence of a lexically-specific boost. Abstract priming is preserved in aphasia, effectively facilitating not only immediate but also longer-lasting structure-message mapping during sentence comprehension.  相似文献   

7.
Di-(2-propylheptyl) phthalate (DPHP) is a plasticizer and has been suggested to be a subchronic toxicant in rats. DPHP has been approved to be used in food containers and handling by the U.S. Food and Drug Administration. The use of DPHP is still increasing, and the risk of human exposure to DPHP via food may be high. Exposure markers measured in human samples are commonly used to monitor human exposure levels. Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and a rat model were used to discover tentative DPHP exposure markers. DPHP and mono-(2-propylheptyl) phthalate (MPHP) were used as the precursors for calculating metabolite candidates using biotransformation mass changes of known enzymatic reactions. A rat model was designed to validate these metabolite candidates as tentative exposure markers. A total of 28 signals show dose–response relationships and these signals contain a few isomers. The chemical structures of 15 tentative exposure marker signals were speculated based on the product ion mass spectra from MS/MS analysis. These 15 signals included 7 chemical structures and some of them may be isomers. The different arrangement of the atoms in space of these isomers should be validated by standard compounds in the future studies. Among the 7 speculated chemical structures, 2 structures were novel tentative DPHP metabolites, and 5 structures have been previously reported in the literature. The results indicate that using UPLC-MS and a rat model can be used to identify tentative toxicant exposure markers.  相似文献   
8.
Rationale:The prone position is commonly used in spinal surgery. There have been many studies on hemodynamic changes in the prone position during general anesthesia. We report a rare case of transient left bundle branch block (LBBB) in a prone position.Patient concern:Electrocardiogram (ECG) of a 64-year-old man scheduled for spinal surgery showed normal sinus rhythm change to LBBB after posture change to the prone position.Diagnosis:Twelve lead ECG revealed LBBB. His coronary angio-computed tomography results showed right coronary artery with 30% to 40% stenosis and left circumflex artery with 40% to 50% stenosis. The patient was diagnosed with stable angina and second-degree atrioventricular block of Mobitz type II.Intervention:Nitroglycerin was administered intravenously during surgery. Adequate oxygen was supplied to the patient. After surgery, the patient was prescribed clopidogrel, statins, angiotensin II receptor blocker, and a permanent pacemaker was inserted.Outcome:Surgery was completed without complications. After surgery, the transient LBBB changed to a normal sinus rhythm. The patient did not complain of chest pain or dyspnea.Lesson:The prone position causes significant hemodynamic changes. A high risk of cardiovascular disease may cause ischemic heart disease and ECG changes. Therefore, careful management is necessary.  相似文献   
9.
肝癌间质及癌旁病变的病理分析   总被引:2,自引:0,他引:2  
目的 研究肝癌间质及癌旁病变的临床病理意义。方法 在 2 0例肝癌组织标本中取 45个癌结节 ,分别在癌结节中间、癌旁肝组织等部位取组织 4块 ,连续切片 ,显微镜下观察。结果  19个结节有完整窦内皮细胞围绕癌巢 ,其中癌结节肉眼小于3cm者 13个 ,大于 3cm者 6个。 2 6个癌结节无完整窦内皮细胞围绕癌巢 ,其中癌结节直径大于 3cm者 2 4个 ,小于 3cm者 2个。2 0例中有 13例合并肝硬化 ,17例有乙型肝炎病毒感染和HBsAg阳性。 结论 病理连续切片 ,显微镜下观察肝癌间质及癌旁病变是预测肝癌患者预后的重要病理学指标  相似文献   
10.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  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