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   289260篇
  免费   27486篇
  国内免费   22467篇
耳鼻咽喉   2207篇
儿科学   2663篇
妇产科学   3085篇
基础医学   34707篇
口腔科学   4675篇
临床医学   40886篇
内科学   40557篇
皮肤病学   2663篇
神经病学   15901篇
特种医学   10857篇
外国民族医学   205篇
外科学   28860篇
综合类   51074篇
现状与发展   79篇
一般理论   27篇
预防医学   17973篇
眼科学   8551篇
药学   31098篇
  330篇
中国医学   17824篇
肿瘤学   24991篇
  2024年   796篇
  2023年   4191篇
  2022年   10418篇
  2021年   15084篇
  2020年   11469篇
  2019年   9866篇
  2018年   10342篇
  2017年   9346篇
  2016年   8780篇
  2015年   13381篇
  2014年   16544篇
  2013年   14292篇
  2012年   21349篇
  2011年   24456篇
  2010年   15424篇
  2009年   12145篇
  2008年   15576篇
  2007年   15377篇
  2006年   15464篇
  2005年   15452篇
  2004年   9394篇
  2003年   8634篇
  2002年   7155篇
  2001年   6302篇
  2000年   6919篇
  1999年   7474篇
  1998年   4830篇
  1997年   4873篇
  1996年   3786篇
  1995年   3609篇
  1994年   2986篇
  1993年   2009篇
  1992年   2238篇
  1991年   1875篇
  1990年   1584篇
  1989年   1349篇
  1988年   1143篇
  1987年   962篇
  1986年   743篇
  1985年   612篇
  1984年   349篇
  1983年   214篇
  1982年   118篇
  1981年   127篇
  1980年   83篇
  1979年   91篇
  1965年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
Bipolar disorder (BD) is a common psychiatric mood disorder affecting more than 1-2% of the general population of different European countries. Unfortunately, there is no objective laboratory-based test to aid BD diagnosis or monitor its progression, and little is known about the molecular basis of BD. Here, we performed a comparative proteomic study to identify differentially expressed plasma proteins in various BD mood states (depressed BD, manic BD, and euthymic BD) relative to healthy controls. A total of 10 euthymic BD, 20 depressed BD, 15 manic BD, and 20 demographically matched healthy control subjects were recruited. Seven high-abundance proteins were immunodepleted in plasma samples from the 4 experimental groups, which were then subjected to proteome-wide expression profiling by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight tandem mass spectrometry. Proteomic results were validated by immunoblotting and bioinformatically analyzed using MetaCore. From a total of 32 proteins identified with 1.5-fold changes in expression compared with healthy controls, 16 proteins were perturbed in BD independent of mood state, while 16 proteins were specifically associated with particular BD mood states. Two mood-independent differential proteins, apolipoprotein (Apo) A1 and Apo L1, suggest that BD pathophysiology may be associated with early perturbations in lipid metabolism. Moreover, down-regulation of one mood-dependent protein, carbonic anhydrase 1 (CA-1), suggests it may be involved in the pathophysiology of depressive episodes in BD. Thus, BD pathophysiology may be associated with early perturbations in lipid metabolism that are independent of mood state, while CA-1 may be involved in the pathophysiology of depressive episodes.  相似文献   
32.
Animal and human studies suggest fish oil and green tea may have protective effect on prostate cancer. Fatty acid synthase (FAS) has been hypothesized to be linked to chemoprotective effects of both compounds. This study evaluated the independent and joint effects of fish oil (FO) and green tea supplement (epigallocatechin-3-gallate, EGCG) on FAS and Ki-67 levels in prostate tissue. Through a double-blinded, randomized controlled trial with 2 × 2 factorial design, 89 men scheduled for repeat prostate biopsy following an initial negative prostate biopsy were randomized into either FO alone (1.9 g DHA + EPA/day), EGCG alone (600 mg/day), a combination of FO and EGCG, or placebo. We used linear mixed-effects models to test the differences of prostate tissue FAS and Ki-67 by immunohistochemistry between pre- and post-intervention within each group, as well as between treatment groups. Results did not show significant difference among treatment groups in pre-to-post-intervention changes of FAS (P = 0.69) or Ki-67 (P = 0.26). Comparing placebo group with any of the treatment groups, we did not find significant difference in FAS or Ki-67 changes (all P > 0.05). Results indicate FO or EGCG supplementation for a short duration may not be sufficient to produce biologically meaningful changes in FAS or Ki-67 levels in prostate tissue.  相似文献   
33.
目的以基因表达数据集资料为研究对象,分析BCAN基因在肾透明细胞癌中的表达情况以及对患者预后的影响。方法在Oncomine数据库中挖掘BCAN在肾透明细胞癌(ccRCC)中的表达情况。从TCGA数据库中获取ccRCC患者临床资料和目的基因的表达信息并进行统计分析。利用GEO数据库中GSE73731数据集的ccRCC样本进行基因富集分析。利用String数据库分析与BCAN相关的蛋白。结果BCAN低表达组的ccRCC患者在病理分期及T分期方面低于高表达组(P<0.001;P=0.001);N分期及M分期差异无统计学意义(P>0.05)。BCAN低表达组患者的总生存期优于高表达组(P=0.033)。BCAN基因高表达组的样本主要富集在KRAS信号通路。结论BCAN可以通过多种途径来促进肿瘤细胞的侵袭能力,有望成为ccRCC不良预后的重要生物标志物之一。  相似文献   
34.
目的 探讨模拟诊疗在留学生心血管内科实习带教中的应用效果。方法 将35名留学生随机编号,分成试验组和对照组。试验组18名学生分成3组(每组6名)进行模拟诊疗教学,对照组17名学生进行常规实习。通过填写评价单和相关的临床能力测试对两组教学效果进行评价。选用SPSS 19.0软件进行t检验。结果 参与模拟诊疗教学的留学生均希望在各科实习中多采用此方法。在临床能力测试方面,试验组学生在病史采集[(22.16±2.17)vs.(20.33±2.03)]、体格检查[(23.05±1.79)vs.(19.78±2.05)]及回答问题[(23.50±1.47)vs.(19.56±1.92)]方面均优于对照组,差异有统计学意义(P<0.05)。但是在病历书写方面,两组差异无统计学意义(P>0.05)。结论 利用高仿真的模拟诊疗教学手段,弥补了留学生在实习期间不能充分接触患者的缺陷,有助于提高其临床操作技能、增强医患沟通能力等医学职业素养。  相似文献   
35.
In this article, a model-free off-policy reinforcement learning algorithm is applied to address the optimal tracking problem based on multiplayer non-zero-sum games for discrete-time linear systems. In contrast to the traditional method and the policy iteration method for solving the optimal tracking problems, the proposed algorithm operates with the system data rather than the knowledge of the system dynamics. For performing the proposed algorithm, an auxiliary augmented system is constructed via assembling the original system and the reference trajectory while a discount factor is introduced into the performance indexes. It is analyzed that the solutions of the proposed algorithm converge to the Nash equilibrium and the result is not influenced by the probing noise. Two simulations are presented to verify the feasibility and effectiveness of the proposed algorithm.  相似文献   
36.
37.
38.
口服异维A酸是目前临床上最为有效的抗痤疮药物,可同时作用于痤疮发病的4个主要环节。异维A酸在皮脂腺细胞内独特的分子作用机制使其具有强大的抑制皮脂腺分泌活性,近来其对痤疮免疫和炎症反应的拮抗作用也越来越受到重视。口服异维A酸主要用于治疗结节囊肿型重度痤疮以及其他治疗效果不好的中、重度寻常痤疮,使用剂量应根据患者的体重、疗效、依从性及不良反应进行综合判定。小剂量[0.25~0.5 mg/(kg·d)]治疗可以显著降低药物的不良反应及增加患者依从性;累积剂量达60~120 mg/kg可以明显降低痤疮复发率。异维A酸不良反应大多以皮肤黏膜为主要表现,严重不良反应罕见,致畸是其最严重的不良反应。口服异维A酸能快速改善痤疮皮损,有效预防痤疮瘢痕形成,改善患者生活质量。  相似文献   
39.
AimsWe previously showed that the protective effects of endothelial progenitor cells (EPCs)‐released exosomes (EPC‐EXs) on endothelium in diabetes. However, whether EPC‐EXs are protective in diabetic ischemic stroke is unknown. Here, we investigated the effects of EPC‐EXs on diabetic stroke mice and tested whether miR‐126 enriched EPC‐EXs (EPC‐EXsmiR126) have enhanced efficacy.MethodsThe db/db mice subjected to ischemic stroke were intravenously administrated with EPC‐EXs 2 hours after ischemic stroke. The infarct volume, cerebral microvascular density (MVD), cerebral blood flow (CBF), neurological function, angiogenesis and neurogenesis, and levels of cleaved caspase‐3, miR‐126, and VEGFR2 were measured on day 2 and 14.ResultsWe found that (a) injected EPC‐EXs merged with brain endothelial cells, neurons, astrocytes, and microglia in the peri‐infarct area; (b) EPC‐EXsmiR126 were more effective than EPC‐EXs in decreasing infarct size and increasing CBF and MVD, and in promoting angiogenesis and neurogenesis as well as neurological functional recovery; (c) These effects were accompanied with downregulated cleaved caspase‐3 on day 2 and vascular endothelial growth factor receptor 2 (VEGFR2) upregulation till day 14.ConclusionOur results indicate that enrichment of miR126 enhanced the therapeutic efficacy of EPC‐EXs on diabetic ischemic stroke by attenuating acute injury and promoting neurological function recovery.  相似文献   
40.
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