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   29392篇
  免费   2839篇
  国内免费   2232篇
耳鼻咽喉   216篇
儿科学   405篇
妇产科学   343篇
基础医学   3381篇
口腔科学   531篇
临床医学   3976篇
内科学   4507篇
皮肤病学   265篇
神经病学   1431篇
特种医学   1268篇
外国民族医学   12篇
外科学   3345篇
综合类   4812篇
现状与发展   6篇
一般理论   3篇
预防医学   1905篇
眼科学   681篇
药学   3163篇
  27篇
中国医学   1581篇
肿瘤学   2605篇
  2024年   91篇
  2023年   438篇
  2022年   1092篇
  2021年   1362篇
  2020年   1025篇
  2019年   933篇
  2018年   961篇
  2017年   911篇
  2016年   935篇
  2015年   1316篇
  2014年   1602篇
  2013年   1461篇
  2012年   1941篇
  2011年   2329篇
  2010年   1492篇
  2009年   1156篇
  2008年   1498篇
  2007年   1616篇
  2006年   1517篇
  2005年   1487篇
  2004年   1126篇
  2003年   1139篇
  2002年   1018篇
  2001年   866篇
  2000年   797篇
  1999年   750篇
  1998年   438篇
  1997年   507篇
  1996年   336篇
  1995年   296篇
  1994年   233篇
  1993年   196篇
  1992年   231篇
  1991年   212篇
  1990年   184篇
  1989年   166篇
  1988年   133篇
  1987年   136篇
  1986年   119篇
  1985年   76篇
  1984年   50篇
  1983年   28篇
  1982年   16篇
  1981年   17篇
  1980年   25篇
  1979年   45篇
  1978年   22篇
  1976年   12篇
  1975年   18篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
摘 要 目的:观察米氮平联合兰索拉唑、伊托必利治疗伴有焦虑抑郁状态的功能性消化不良(FD)患者的疗效和不良反应。方法:108例焦虑抑郁伴FD患者随机分为米氮平组、氟哌噻吨美利曲辛组和对照组各36例。对照组予兰索拉唑片和伊托必利片常规治疗,米氮平组在对照组基础上加用米氮平片,氟哌噻吨美利曲辛组在对照组基础上加用氟哌噻吨美利曲辛片。疗程均为6周。比较3组患者治疗前与治疗2,4,6周后的上消化道症状评分与HAMD评分变化,观察3组药品不良反应发生情况。结果:3组FD症状评分比较,治疗2周后,米氮平组明显降低,优于对照组(P<0.05);治疗4周后,氟哌噻吨美利曲辛组优于对照组(P<0.05),米氮平组优于氟哌噻吨美利曲辛组(P<0.05)。3组HAMD评分比较,治疗2周后,米氮平组明显降低,优于对照组及氟哌噻吨美利曲辛组(P<0.05);治疗4周后,氟哌噻吨美利曲辛组优于对照组(P<0.05);治疗4,6周后,米氮平组与氟哌噻吨美利曲辛组差异无统计学意义(P>0.05)。米氮平组与氟哌噻吨美利曲辛组不良反应发生率差异无统计学意义(P>0.05),对照组分别与两观察组比较,不良反应发生率差异也无统计学意义(P>0.05)。结论:米氮平联合兰索拉唑、伊托必利治疗伴焦虑抑郁的FD患者,能显著改善患者的功能性消化不良和焦虑抑郁症状,起效快、效果好、安全性高,有较高临床应用价值。  相似文献   
992.
Magnesium hydride is regarded as one of the most ideal candidates for hydrogen storage, but its relatively high operating temperatures and slow kinetics always hinder its commercial applications. Herein, we first fabricated hard-carbon-sphere-wrapped Ni (Ni/HCS) via a mild chemical method; subsequently, the as-prepared additive was introduced to fabricate an Mg–Ni/HCS composite by using hydriding combustion synthesis. Hard carbon spheres (HCS) effectively inhibited the agglomeration of hydride particles during hydrogen storage cycling; they could also provide active sites to promote the nucleation of Mg-based hydrides. During the hydriding combustion synthesis procedure, in situ-formed Mg2NiH4 could induce the absorption of MgH2, thus triggering its hydrogen properties. Remarkable enhancement in hydrogen absorption properties of the composite was found. The composite absorbed 6.0 wt% H2 within 5 min at 275 °C; moreover, even at 75 °C, it could still absorb 3.5 wt% H2. Furthermore, it delivered a high reversible hydrogen absorption capacity of 6.2 wt% and excellent rate capability at 350 °C. It was also demonstrated that the composite could release 6.2 wt% H2 at 350 °C within 5 min. A rather low activation energy value (65.9 kJ mol−1) for the dehydrogenation of MgH2 was calculated as compared to that for commercial MgH2 (133.5 kJ mol−1).

Magnesium hydride is regarded as one of the most ideal candidates for hydrogen storage, but its relatively high operating temperatures and slow kinetics always hinder its commercial applications.  相似文献   
993.
目的 了解小儿肾小球疾病病理与临床分布特点。方法 收集353例肾活检患儿资料进行回顾性分析。结果 353例患儿中诊断为紫癜性肾炎117例(33.1%),孤立性血尿94例(26.6%),原发性肾病综合征87例(24.6%),急性肾炎综合征23例(6.5%),其次还有乙肝相关性肾炎、狼疮性肾炎、孤立性蛋白尿、慢性肾炎等。肾小球疾病中以原发性肾小球疾病最为常见(206例,占58.4%),病理改变主要为:系膜增生性肾小球肾炎(MsPGN)66例,占32.0%; IgA肾病(IgA N)54例,占26.2%;轻微病变37例,占18.0%;其他还包括微小病变(MCD)、膜增生性肾小球肾炎(MPGN)、膜性肾病(MN)、毛细血管增生性肾小球肾炎等。继发性肾小球疾病以紫癜性肾炎最常见。结论 肾小球疾病以原发性肾小球疾病为主,临床诊断以孤立性血尿最常见,继发性肾炎以紫癜性肾炎最常见。  相似文献   
994.
目的 使用高强度聚焦超声(HIFU)对犬周围动脉闭塞模型进行腰交感神经节阻滞,观察对外周血5-羟色胺(5-HT)及前列腺素E2(PGE2)的影响,探讨其治疗缺血性疼痛的可能机制。 方法 26只杂种家犬随机分为3组: HIFU疗组(A组),非治疗组(B组),正常对照组(C组)。A组和B组在无菌条件下制作后肢缺血模型, A组术后2周用HIFU阻滞第2~6腰交感神经节,B组不予处理。A组和B组每次随机选2只犬在治疗0周(造模后2周)、治疗后1周、2周、1个月、2个月、4个月分别抽血检测血5-羟色胺及前列腺素E2。 结果 A组和B组在治疗0周外周血5-HT和PGE2含量与C组相比,均明显升高且差异有统计学意义(P<0.05)。A组治疗1周后外周血5-HT及PGE2浓度呈逐渐下降趋势,而B组则总体呈现增高趋势。两组治疗1周后各时间点外周血5-HT及PGE2比较,差异均有统计学意义(P<0.05)。 结论 慢性周围动脉闭塞缺血致痛可使犬外周血5-HT和PGE2含量升高,HIFU阻滞腰交感神经节缓解疼痛的机制可能与降低外周血5-HT和PGE2含量有关。  相似文献   
995.
Pyrrolizidine alkaloids (PAs) are hepatotoxic, genotoxic, and carcinogenic in experimental animals. Because of their widespread distribution in the world, PA-containing plants are probably the most common poisonous plants affecting livestock, wildlife, and humans. Upon metabolism, PAs generate reactive dehydro-PAs and other pyrrolic metabolites that lead to toxicity. Dehydro-PAs are known to react with glutathione (GSH) to form 7-GSH-(+/−)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (7-GS-DHP) in vivo and in vitro and 7,9-diGS-DHP in vitro. To date, the phototoxicity of GS-DHP adducts has not been well studied. In this study, we synthesized 7-GS-DHP, a tentatively assigned 9-GS-DHP, and two enantiomeric 7,9-diGS-DHP adducts by reaction of dehydromonocrotaline with GSH. The two 7,9-diGS-DHPs were separated by high performance liquid chromatography (HPLC) and their structures were characterized by 1H nuclear magnetic resonance (NMR) and 1H–1H correlation spectroscopy (COSY) NMR spectral analysis. Photoirradiation of 7-GS-DHP, 9-GS-DHP, and the two 7,9-diGS-DHPs as well as dehydromonocrotaline, dehydroheliotrine, and the 7-R enantiomer of DHP (DHR), by UVA light at 0 J/cm2, 14 J/cm2, and 35 J/cm2 in the presence of a lipid, methyl linoleate, all resulted in lipid peroxidation in a light dose-responsive manner. The levels of lipid peroxidation induced by the two isomeric 7,9-diGS-DHPs were significantly higher than that by 7-GS-DHP and 9-GS-DHP. When 7,9-diGS-DHP was irradiated in the presence of sodium azide (NaN3), the level of lipid peroxidation decreased; lipid peroxidation was enhanced when methanol was replaced by deuterated methanol. These results suggest that singlet oxygen is a product induced by the irradiation of 7,9-diGS-DHP. When irradiated in the presence of superoxide dismutase (SOD), the level of lipid peroxidation decreased, indicating that lipid peroxidation is also mediated by superoxide. These results indicate that lipid peroxidation is mediated by reactive oxygen species (ROS). These results suggest that 7,9-diGS-DHPs are phototoxic, generating lipid peroxidation mediated by ROS.  相似文献   
996.
997.
Background:Epilepsy is 1 of the common neurodevelopmental diseases. It can affect about 0.5% to 1.0% of the population regardless of their race and social class. Despite the development of a wide range of treatments, there remaining about one-third of patients still experience seizures. Chinese herbal compounds containing scorpion (CHCCS) have shown an outstanding curative effect on nerve protection and epilepsy. But there''s no study to assess its clinical efficacy and safety.Methods:Each data of CHCCS in treating epilepsy from related English and Chinese databases will be searched. The primary outcome is the efficacy of the CHCCS on epilepsy. And the secondary outcomes include recurrence rate and side effects. The risk of bias will be assessed, and RevMan5.3 and Stata14.0 will be performed for meta-analysis. Finally, we will assess the level of the resulting evidence.Results:The results of the study will be combined with current evidence and published in a peer-reviewed journal.Conclusions:This study will specifically investigate the effectiveness and safety of CHCCS in treating epilepsy.INPLASY registration number:INPLASY202120056.  相似文献   
998.
Rationale:To describe the clinical effects of human umbilical cord mesenchymal stem cells (UCMSCs) combined with allogenic platelet-rich fibrin (PRF) for the treatment of lower limb ischemia in an elderly patient.Patient concerns:The patient was a 93-year-old Chinese woman with bilateral foot gangrene and ulcers lasting for 6 months. She had a prior history of Behcet''s disease.Diagnoses:The admitting diagnosis for this episode was atherosclerosis bilateral limb ischemia.Interventions:First, treatment consisting of immunosuppressants, anticoagulation, antiplatelets, and anti-microbials were instituted. A UCMSC suspension was administered intravenously and injected into the lower limbs twice. An allogenic PRF membrane was externally applied 15 times over the lower limbs.Outcomes:The patient''s pain improved and the 6 ulcers healed.Lessons:The combination of UCMSCs with a PRF membrane for the treatment of lower limb ischemia in an elderly patient is effective and safe. More and larger trials are needed before incorporating this therapy into mainstream treatment.  相似文献   
999.
Background:At present, Liver Cirrhosis (LC) is common in most later liver and gallbladder diseases that its morbidity and mortality seriously affect human health. The limitation and effectiveness of western medicine on LC have become a huge clinical challenge. However, a large number of clinical studies have shown that Yi-guan decoction has become a complementary treatment for LC. Therefore, this systematic review will aim to explore the safety and feasibility of Yi-guan decoction in the treatment of LC.Methods:We will conduct a comprehensive literature search in Medline, PubMed, Cochrane Database of Systematic Reviews, Embase, Chinese Biomedical Literatures Database, China National Knowledge Infrastructure, Wang Fang Database, Chinese Scientific Journal Database from inception to December 2020 without any language restriction, In addition, relevant literature will be searched manually. The main subject terms searched: “Yi-guan decoction” “cirrhosis” “LC”. Data entry will be performed by 2 researchers separately. Primary outcomes will be concluded: Liver function indicators: Total bilirubin, Alanine transaminase, Aspartate aminotransferase, etc. Secondary outcome indicators: Total effective rate, Nutrition index, Survival analysis, Adverse events; All randomized controlled trials collected in this study will be evaluated and rated using the Cochrane risk-of-biasassessment tool. Meta-analysis will be performed using RevMan 5.4.0 software. The heterogeneity test will be conducted between the studies, P < .1 and I2 > 50% are the thresholds for the tests. Using solid effect model or random effect model will be based on its heterogeneity value.Results:This systematic review provides a theoretical basis for Yi-guan decoction to treat LC, we will report this result soon.Conclusion:This study will explore Yi-guan decoction can will be used as one of the non drug therapies to prevent or treat LC.Trial registration number:INPLASY2020120114.  相似文献   
1000.
Background:Essential hypertension is the primary cause of death and disability and it has become a major public health problem globally. Yufeng Ningxin (YFNX) is a commonly used Chinese patent medicine in treating essential hypertension. The objective of this protocol is to evaluate the effectiveness and safety of YFNX for the treatment of essential hypertension.Methods:Randomized controlled trials (RCTs) in relation to the effectiveness and safety of YFNX in the treatment of essential hypertension will be systematically searched and collected from the following databases: PubMed, EMBASE, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang Database, Chinese Biomedical Literature Database, and Chinese Scientific Journal Database from the database inception to January 1, 2021. The data screening and extraction will be carried out by 2 different reviewers. The quality of randomized controlled trials will be assessed based on the version 2 of the risk-of-bias tool for randomized trials (RoB 2) in the Cochrane Handbook. The reduction of systolic blood pressure (SBP) and diastolic blood pressure (DBP) will be served as the primary outcome. The secondary outcomes will include average SBP and average DBP during the day and the night measured by 24 hours ambulatory blood pressure monitoring, the clinical effectiveness rate, scores of traditional Chinese medicine syndrome, clinical symptoms, the quality of life and adverse events. Statistical analysis will be conducted with Review Manager 5.3 and STATA 14.0 software.Conclusion:This systematic review will provide strong evidence to assess the effectiveness and safety of YFNX in the treatment of essential hypertension.Trial registration number:INPLASY202110059.  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