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   152036篇
  免费   12530篇
  国内免费   4862篇
耳鼻咽喉   1060篇
儿科学   2846篇
妇产科学   1467篇
基础医学   23688篇
口腔科学   2978篇
临床医学   15253篇
内科学   19815篇
皮肤病学   1500篇
神经病学   7343篇
特种医学   3135篇
外国民族医学   22篇
外科学   12643篇
综合类   24182篇
现状与发展   11篇
一般理论   25篇
预防医学   10549篇
眼科学   4184篇
药学   16342篇
  14篇
中国医学   7912篇
肿瘤学   14459篇
  2024年   207篇
  2023年   1708篇
  2022年   2960篇
  2021年   5307篇
  2020年   4682篇
  2019年   4876篇
  2018年   4788篇
  2017年   4760篇
  2016年   4891篇
  2015年   4945篇
  2014年   7738篇
  2013年   8743篇
  2012年   7305篇
  2011年   8449篇
  2010年   7351篇
  2009年   7235篇
  2008年   7299篇
  2007年   8380篇
  2006年   7693篇
  2005年   7737篇
  2004年   6773篇
  2003年   6021篇
  2002年   4442篇
  2001年   4404篇
  2000年   3587篇
  1999年   3353篇
  1998年   2368篇
  1997年   2090篇
  1996年   2204篇
  1995年   2109篇
  1994年   1854篇
  1993年   1693篇
  1992年   1450篇
  1991年   1262篇
  1990年   1052篇
  1989年   993篇
  1988年   933篇
  1987年   713篇
  1986年   534篇
  1985年   611篇
  1984年   635篇
  1983年   396篇
  1982年   491篇
  1981年   417篇
  1980年   362篇
  1979年   301篇
  1978年   247篇
  1977年   201篇
  1976年   237篇
  1975年   149篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
[目的]研究真武汤合苓桂术甘汤对心肾综合征大鼠模型水钠潴留的作用机制。[方法]将60只雄性SD大鼠随机分为两组,即空白组与手术组,空白组大鼠常规饲养,手术组大鼠经5/6肾切除联合异丙肾上腺素皮下注射制备心肾综合征模型,剔除死亡大鼠后,将手术组剩余成模大鼠按体质量分层随机分为空白组、中药组、常规治疗组。中药组给予真武汤合苓桂术甘汤灌胃,给药量为7.29 g生药/(kg·d);常规治疗组给予贝那普利(0.45 mg/kg)+呋塞米(1.8m g/kg);空白组予以等容积生理盐水灌胃,每日1次,连续6周。观察实验过程中各组大鼠的精神状态、活动情况、灵敏度、毛发情况、食欲、大小便等一般情况及死亡情况,比较各组灌胃前、灌胃6周后的血清脑钠肽(BNP)、血肌酐(Scr)、血尿素氮(BUN)、尿水通道蛋白2(AQP2)的前后差值情况。[结果]灌胃6周后,中药组大鼠一般情况较灌胃前改善、喘息不明显,常规治疗组一般情况同样较灌胃前改善。通过比较治疗前后各组大鼠实验室指标差值发现,中药组与常规治疗组BNP均下降,中药改善大鼠心力衰竭情况接近常规治疗组水平,两组下降水平无统计学差异(P0.05);中药组Scr水平较前下降,常规治疗组Scr水平升高;中药组尿AQP2水平较前略增高,与空白组尿AQP2水平无统计学差异(P0.05),常规治疗组尿AQP2水平较前明显升高。[结论]心肾综合征大鼠尿AQP2的表达主要由肾脏调控,AQP2可作为心肾综合征水钠潴留状态的参考指标,真武汤合苓桂术甘汤改善心肾综合征大鼠水钠潴留状态的作用机制可能是通过抑制大鼠肾脏AQP2过度表达,减少水的重吸收,改善了水钠潴留状态。  相似文献   
102.
Inflammation plays a critical role in the development of ventilator-induced lung injury (VILI). Endoplasmic reticulum (ER) stress is associated with a variety of diseases through the modulation of inflammatory responses. However, little is known about how ER stress is implicated in VILI. In this study, murine mechanical ventilation models were constructed. Total protein and inflammatory cytokines were measured in bronchoalveolar lavage fluid (BALF), and lung tissue injury was assessed by histology. Our data revealed that mice subjected to high tidal ventilation (TV) for 4 h showed more severe pulmonary edema and inflammation than those of mice with spontaneous breathing and low TV-treatment. In addition, the high TV-treated animals upregulated the ER stress markers GRP78, CHOP, p-IRE1α, TRAF2, and p-NF-κB expression at both the mRNA and protein levels in lung tissue. Administration of thapsigargin exacerbated the histological changes, inflammation and expression of GRP78 and CHOP after high TV, but treatment with ER stress and IRE1α kinase inhibitors attenuated the pathological damage and downregulated the high expression of GRP78, CHOP, p-IRE1α, TRAF2, and p-NF-κB, suggesting that ER stress is involved in VILI though the IRE1α/TRAF2/NF-κB signaling pathway in mice.  相似文献   
103.
目的建立了一种高效液相色谱-三重四极杆串联质谱法,对氯沙坦钾原料药中遗传毒性杂质N-亚硝基-N-甲基-4-氨基丁酸(NMBA)进行测定。方法色谱柱为岛津Shim-pack XR-ODSⅡ色谱柱(2.0 mm×150 mm,2.2μm),流动相为0.1%甲酸水溶液(A)和甲醇(B),进行梯度洗脱,流速0.3 mL·min^-1,柱温为40℃,采用ESI离子化-三重四极杆质谱多反应监测(MRM)正离子模式检测,碰撞电压分别为-11,-13和-13 V,碰撞气氩气270 kPa,NMBA的离子对分别为m/z 147.15→117.10,147.15→87.10和147.15→44.10。结果该方法中NMBA在1~100 ng·mL^-1内线性关系良好,日内和日间的保留时间和峰面积的重复性良好(RSD均小于1.10%,n=6和n=18),低、中、高3个浓度的平均回收率在94.40%~98.04%之间。结论本方法简单方便,可快速有效的对氯沙坦钾原料药中NMBA进行限度检查并实现定量分析。  相似文献   
104.
《Clinical neurophysiology》2020,131(1):213-224
ObjectiveSystematically review the abnormalities in event related potential (ERP) recorded in Rett Syndrome (RTT) patients and animals in search of translational biomarkers of deficits related to the particular neurophysiological processes of known genetic origin (MECP2 mutations).MethodsPubmed, ISI Web of Knowledge and BIORXIV were searched for the relevant articles according to PRISMA standards.ResultsERP components are generally delayed across all sensory modalities both in RTT patients and its animal model, while findings on ERPs amplitude strongly depend on stimulus properties and presentation rate. Studies on RTT animal models uncovered the abnormalities in the excitatory and inhibitory transmission as critical mechanisms underlying the ERPs changes, but showed that even similar ERP alterations in auditory and visual domains have a diverse neural basis. A range of novel approaches has been developed in animal studies bringing along the meaningful neurophysiological interpretation of ERP measures in RTT patients.ConclusionsWhile there is a clear evidence for sensory ERPs abnormalities in RTT, to further advance the field there is a need in a large-scale ERP studies with the functionally-relevant experimental paradigms.SignificanceThe review provides insights into domain-specific neural basis of the ERP abnormalities and promotes clinical application of the ERP measures as the non-invasive functional biomarkers of RTT pathophysiology.  相似文献   
105.
Background: Little is known of stroke outcomes in low- and middle-income countries with limited formal stroke rehabilitation services and of homebased-stroke services delivered within the primary health care (PHC) context by community health workers (CHWs).

Objectives: To describe and analyze the outcomes of patients with stroke from a rural PHC setting in the Western Cape, South Africa.

Methods: In a longitudinal survey, 93 stroke patients, referred to home and community-based care services (HCBC) between June 2015 and December 2017, were assessed at baseline, one month and three months. Changes in function (Barthel Index (BI)), caregiver strain (Caregiver Strain Index (CSI)), impact of environmental factors and satisfaction with stroke care were measured.

Results: HCBC was delayed, fragmented and brief (median session duration 20 minutes (IQR 15.0–30.0)). Although function improved significantly, dependence remained high: median BI score changed from 40.0 (IQR 15.0–70.0) to 62.5 (IQR 30.0–81.25) (p = .019). A third (33.0% (30/91)) of caregivers initially experienced strain and the median CSI score remained 3.0 (IQR 0.0–7.0) (p = .672). Overall, patient and caregiver satisfaction with HCBC was low with only 46.9% (31/66) of caregivers and 17.4% (12/69) of patients satisfied with all aspects of care. Only 47.6% of assistive product needs were met. Environmental factors negatively impacted on patient function and caregiving.

Conclusions: Clinical practice pathways and referral guidelines should be developed for the HCBC platform. Specific training of CHWs, focusing on how to educate, support and train family caregivers, provide assistive devices and refer to health services is needed.  相似文献   

106.
Among the numerous signaling pathways involved in tumorigenesis, PI3K‐AKT‐mTOR is a key one that regulates diverse cellular functions. However, its prognostic value in esophageal carcinoma remains unclear. In our study, we examined the immunohistochemical expression of phosphorylated (p‐) AKT, mTOR, p70S6K and 4E‐BP1 along with the mutational status of PIK3CA and AKT1 genes by High Resolution Melting Analysis and Pyrosequencing in 44 esophageal carcinomas. The results were correlated with the clinicopathological characteristics of the patients in an effort to define their possible prognostic significance. Total p‐mTOR cytoplasmic expression, assessed in 10 random areas, was positively correlated with tumor stage (Kruskal–Wallis ANOVA, I/II vs III/IV, p = 0.0500). Μoreover, maximum p‐mTOR cytoplasmic immunoexpression, estimated in hot spot areas, was positively associated with tumor grade (Mann–Whitney U test, I/II vs III, p = 0.0565). Interestingly, p‐4E‐BP1 immunoreactivity was negatively correlated with tumor histological grade (Mann–Whitney U test, I/II vs III, p = 0.0427). No mutation was observed in exons 9 and 20 of PIK3CA gene and in exon 4 of AKT1 gene. In conclusion, our findings depict the presence of activated PI3K/AKT/mTOR pathway in esophageal cancer bringing forward p‐mTOR and p‐4E‐BP1 for their potential role in esophageal carcinogenesis. Additional studies are warranted to validate our findings.  相似文献   
107.
108.
109.
ncRNA/miRNA在多种实体肿瘤中表达异常,参与肿瘤的增殖、侵袭、转移。胰腺癌是发病率较高、死亡率高的恶性肿瘤,通过深入研究lncRNA/miRNA在胰腺癌发生发展中的分子机制,可为胰腺癌的治疗提供新的靶点。  相似文献   
110.
同步放化疗是不可手术局部晚期食管癌的标准治疗模式,国际推荐根治性放疗剂量为50.0~50.4Gy,但中国食管癌与西方国家在病理类型、生物学行为等方面大有不同,行根治性放疗剂量仍倾向于60Gy。增加放疗剂量能否带来生存获益成为临床亟待解决的问题。有研究认为高剂量放疗可提高局控率、改善生存,但也有研究认为提高剂量未能带来生存获益,且可增加不良反应事件发生率。因此,本文就食管癌根治性放疗剂量对预后的影响进行探讨,并通过放化疗后疗效评估对放疗剂量做出适当调整,以期达个体化放疗。  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