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   1812篇
  免费   94篇
  国内免费   13篇
耳鼻咽喉   11篇
儿科学   57篇
妇产科学   42篇
基础医学   163篇
口腔科学   48篇
临床医学   175篇
内科学   295篇
皮肤病学   59篇
神经病学   122篇
特种医学   68篇
外科学   255篇
综合类   47篇
一般理论   1篇
预防医学   110篇
眼科学   79篇
药学   224篇
中国医学   26篇
肿瘤学   137篇
  2024年   4篇
  2023年   32篇
  2022年   66篇
  2021年   113篇
  2020年   73篇
  2019年   143篇
  2018年   98篇
  2017年   68篇
  2016年   84篇
  2015年   77篇
  2014年   86篇
  2013年   112篇
  2012年   143篇
  2011年   145篇
  2010年   71篇
  2009年   66篇
  2008年   79篇
  2007年   81篇
  2006年   78篇
  2005年   39篇
  2004年   37篇
  2003年   25篇
  2002年   25篇
  2001年   15篇
  2000年   8篇
  1999年   13篇
  1998年   4篇
  1997年   5篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   3篇
  1992年   19篇
  1991年   13篇
  1990年   9篇
  1989年   11篇
  1988年   12篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   9篇
  1982年   4篇
  1981年   2篇
  1979年   5篇
  1975年   4篇
  1974年   4篇
  1971年   4篇
  1967年   1篇
  1965年   2篇
排序方式: 共有1919条查询结果,搜索用时 0 毫秒
91.
In order to develop a possible C-X-C chemokine receptor type 4 (CXCR4) imaging agent for oncological scintigraphy, [67Ga]-labeled 1,1′-[1,4-Phenylene-bis(methylene)]bis(1,4,8,11-tetraazacyclotetradecane) ([67Ga]-AMD3100) was prepared by using [67Ga]GaCl3 and AMD-3100 for 2 h at 50 °C (radiochemical purity: >95% ITLC, >99% HPLC, specific activity: 1800–2000 TBq/mmol) in acetate buffer. The stability of the complex was checked in the presence of human serum (37 °C) and in the final formulation for four days. The biodistribution of the labeled compound in the vital organs of wild type Sprague-Dawley rats was determined and compared with that of the free Ga3+ cation up to 48 h. Considering the spleen as the target organ, the best target:non target ratios were obtained 48 h post-injection (spleen:blood ratio; 14.5 and spleen:muscle ratio; 88.4). Initial SPECT images and biodistribution results in the wild type rats matched each other and demonstrated rapid washout of the tracer from the urinary tract. SPECT images in human breast carcinoma-bearing mice demonstrated a detectable tumor uptake in 48 h post-injection.  相似文献   
92.
Nowadays, with comprehensive employment of the internet, healthcare delivery services is provided remotely by telecare medicine information systems (TMISs). A secure mechanism for authentication and key agreement is one of the most important security requirements for TMISs. Recently, Tan proposed a user anonymity preserving three-factor authentication scheme for TMIS. The present paper shows that Tan’s scheme is vulnerable to replay attacks and Denial-of-Service attacks. In order to overcome these security flaws, a new and efficient three-factor anonymous authentication and key agreement scheme for TMIS is proposed. Security and performance analysis shows superiority of the proposed scheme in comparison with previously proposed schemes that are related to security of TMISs.  相似文献   
93.
Corchorus olitorius L. is a nutritious green leafy vegetable that is eaten as a viscous soup in African and Middle Eastern cultures. The purpose of this review is to highlight the nutritional and nutraceutical potential of this plant. The leaves of C. olitorius are rich providers of minerals as calcium and iron in addition to vitamins B1, B2, folic acid C and E. The leaves contain numerous compounds having several biological effects including antidiabetic and antioxidant properties. Besides, the leaves comprise other phytochemicals such as cardiac glycosides, terpenes, flavonoids, fatty acids, hydrocarbons and phenolics. Various extracts of C. olitorius were shown to exhibit antioxidant, anti-inflammatory, hepatoprotective, antihyperlipidemic, immunostimulant, antitumor, antimicrobial, antidiabetic, analgesic, wound-healing properties and cardioprotective activities.

Corchorus olitorius L. is a nutritious green leafy vegetable that is eaten as a viscous soup in African and Middle Eastern cultures.  相似文献   
94.
95.
Hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal morbidity and mortality. Electroencephalography (EEG) and brain magnetic resonance imaging (MRI) are frequently performed in these infants, but the prognostic value of the combined use of EEG and MRI needs additional exploration. The purpose of this study was to investigate, in neonates with HIE, the role of early EEG and conventional MRI in the prediction of infants at risk for persistent encephalopathy at 18 months of age. Thirty-four term infants with HIE were enrolled in this prospective study. EEG was recorded within the first 72 hours after birth and a brain MRI scan was done between 1 and 4 weeks of age. Denver Developmental Screening Test II was performed at 6, 12, and 18 months of age. Three infants (9%) had mild HIE, 21 infants (62%) had moderate HIE, and 10 infants (29%) had severe HIE. The EEG background was normal, moderately, severely, and extremely discontinuous in eight (24%), three (9%), sixteen (47%), and seven (20%) neonates, respectively. EEG background activities correlated significantly with HIE severity (p = 0.0001). MRI findings significantly correlated with EEG background (p = 0.001). Normal MRI scans and minimal basal ganglia lesions were always associated with normal EEG background. Patients with severe basal ganglia and thalamic lesions in MRI (n = 2) had extreme discontinuous EEG background. For the prediction of poor outcomes, abnormal EEG background activity had a sensitivity (Sn) = 100%, a specificity (Sp) = 100%, positive predictive value (PPV) = 100%, and negative predictive value (NPV) = 100%, whereas values of abnormal MRI scans were Sn of 100%, Sp = 43%, PPV = 82%, and NPV=100%. EEG background activity is the best element to predict abnormal outcomes. Severe basal ganglia and thalamic injuries on MRI scans are associated with poor outcomes. Otherwise, MRI does not contribute to the prediction of outcomes at 18 months of age.  相似文献   
96.
Introduction: Epilepsy is a chronic medical disease in one third of patients and is associated with comorbid adverse somatic conditions due to epilepsy itself or its long-term treatment with antiepileptic drugs (AEDs). Data from experimental, cross-sectional and prospective studies have evidence for the deleterious effect of some AEDs on the auditory and vestibular systems. These abnormalities may be reversible or irreversible.

Areas covered: This article review the evidence that long-term treatment with some antiepileptic drugs (AEDs) [e.g. carbamazepine, phenytoin, valproate, lamotrigine, gabapentin, vigabatrin and oxcarbazepine] (even in therapeutic drug doses) may result in tinnitus, phonophobia, sensorineural hearing loss, dizziness, ataxia, disequilibrium, imbalance, nystagmus, abnormalities in saccadic and pursuit eye movements and delayed conduction within the cochlea, auditory nerve and brainstem auditory pathways evidenced by abnormalities in Brainstem auditory evoked potentials and nystagmography recordings indicating auditory and central and/or peripheral vestibular dysfunctions.

Expert opinion: Identification of monitoring of patients at high risk for developing audio-vestibular manifestations is necessary for appropriate preventive and therapeutic measures.  相似文献   

97.
Our aim in this cross-sectional study was to assess the cognitive determinants of Cervical Cancer Screening Behavior (CCSB) among housewife women in Islamabad County, Iran. Through multistage random sampling we recruited and interviewed 280 housewife women. The women who perceived more benefits of performing the Pap test (OR = 1.11), and perceived fewer barriers (OR = 0.915), and higher self-efficacy to perform the test (OR = 1.12) were more likely to have a CCSB in the previous three years. Our findings are informative for the development of targeted interventions to foster CCSB among housewife women.  相似文献   
98.
Introduction: Ocular dysfunctions and toxicities induced by antiepileptic drugs (AEDs) are rarely reviewed and not frequently received attention by treating physicians compared to other adverse effects (e.g. endocrinologic, cognitive and metabolic). However, some are frequent and progressive even in therapeutic concentrations or result in permanent blindness. Although some adverse effects are non-specific, others are related to the specific pharmacodynamics of the drug.

Areas covered: This review was written after detailed search in PubMed, EMBASE, ISI web, SciELO, Scopus, and Cochrane Central Register databases (from 1970 to 2019). It summarized the reported ophthalmologic adverse effects of the currently available AEDs; their risks and possible pathogenic mechanisms. They include ocular motility dysfunctions, retinopathy, maculopathy, glaucoma, myopia, optic neuropathy, and impaired retinal vascular autoregulation. In general, ophthalmo-neuro- or retino-toxic adverse effects of AEDs are classified as type A (dose-dependent), type B (host-dependent or idiosyncratic) or type C which is due to the cumulative effect from long-term use.

Expert opinion: Ocular adverse effects of AEDs are rarely reviewed although some are frequent or may result in permanent blindness. Increasing knowledge of their incidence and improving understanding of their risks and pathogenic mechanisms are crucial for monitoring, prevention, and management of patients’ at risk.  相似文献   

99.
100.
Growing evidence sheds light on the use of flavonoids as the promising alternatives for the treatment of chronic conditions, including cancer and neurodegenerative disorders. Accordingly, in the present study, we aimed at evaluating the effects of oral intake of two structurally different flavonoids 5-hydroxy-6,7,4?-trimethoxyflavone (flavone 1) and 5,7,4?-trihydroxyflavone (flavone 2) on recognition memory, hippocampal protein level of immediate early gene cFos and mitochondrial dynamic markers in Amyloid β (Aβ)-injected rats. Recognition aspect of memory and level of proteins were measured using novel object recognition test and Western blot, respectively. Our data indicated that even though flavone 1 was more effective than flavone 2 to prevent memory impairment, feeding with both flavones alleviated memory in Aβ-injected rats. Furthermore, in flavones-administered rats, mitochondrial dynamic balancing returned to the control level by the decline in Dynamin-related protein-1 protein level, a known marker for mitochondrial fission, and elevation in protein level of mitochondrial fusion factors Mitofusins 1 and 2. In parallel with behavior results, flavone 1 was more effectual on mitochondrial dynamic moderating. The more neuroprotective effects of flavone 1 could be attributed to its methylated structure leading to crossing of the blood-brain barrier with ease and metabolic stability and bioactivity.  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