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   13162篇
  免费   1262篇
  国内免费   701篇
耳鼻咽喉   145篇
儿科学   134篇
妇产科学   126篇
基础医学   1671篇
口腔科学   212篇
临床医学   1666篇
内科学   1857篇
皮肤病学   323篇
神经病学   775篇
特种医学   684篇
外国民族医学   5篇
外科学   1728篇
综合类   1799篇
现状与发展   1篇
一般理论   4篇
预防医学   848篇
眼科学   244篇
药学   1270篇
  3篇
中国医学   712篇
肿瘤学   918篇
  2024年   25篇
  2023年   159篇
  2022年   228篇
  2021年   579篇
  2020年   431篇
  2019年   459篇
  2018年   456篇
  2017年   408篇
  2016年   411篇
  2015年   613篇
  2014年   798篇
  2013年   729篇
  2012年   1021篇
  2011年   1096篇
  2010年   719篇
  2009年   538篇
  2008年   723篇
  2007年   700篇
  2006年   685篇
  2005年   682篇
  2004年   479篇
  2003年   562篇
  2002年   479篇
  2001年   373篇
  2000年   299篇
  1999年   242篇
  1998年   170篇
  1997年   129篇
  1996年   120篇
  1995年   106篇
  1994年   82篇
  1993年   56篇
  1992年   77篇
  1991年   73篇
  1990年   54篇
  1989年   66篇
  1988年   45篇
  1987年   51篇
  1986年   39篇
  1985年   27篇
  1984年   25篇
  1983年   13篇
  1982年   9篇
  1981年   10篇
  1980年   7篇
  1979年   11篇
  1978年   5篇
  1977年   8篇
  1976年   5篇
  1975年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A total of 28 staphylococcal isolates from human clinical specimens belonging to the Staphylococcus sciuri group were identified and characterized. The API Staph and ID32 STAPH correctly identified S. sciuri and S. lentus but not S. vitulinus strains. Identification to the subspecies level was possible only by a PCR-based method.  相似文献   
102.
原发性中枢神经系统恶性淋巴瘤MR表现及其病理学基础   总被引:5,自引:0,他引:5  
目的 研究原发性中枢神经系统恶性淋巴瘤(PCNSL)的MR表现及其病理学基础。方法 分析13例手术病理证实的原发性中枢神经系统恶性淋巴瘤的临床病理及MR表现。结果 13例中单发肿瘤4例,多发肿瘤9例,共计36个病灶。13例病变均累及幕上,其中8例病灶位于深部脑白质近脑室旁。肿瘤平均最大径为3.2cm。T1WI略低信号28个,T2WI等信号24个。28个病灶呈均匀强化。肿瘤水肿及占位效应相对较轻。2例PCNSL行MR动态增强扫描,早期强化均不明显,时间-信号强度曲线呈缓慢上升型。病理上肿瘤细胞弥漫分布,瘤细胞大小较一致,细胞质少,细胞核大,染色质颗粒粗,可见瘤细胞围绕血管呈袖套样浸润,少见明显的出血及片状坏死,未见钙化,病理均为非霍奇金淋巴瘤。结论 原发性中枢神经系统恶性淋巴瘤的病理基础决定其MR增强形态、占位程度以及肿瘤发生部位具有一定特征,运用不同的MR影像学检查方法和技术,在多数情况下可以做出术前正确诊断。  相似文献   
103.
Bosch–Boonstra–Schaaf Optic Atrophy Syndrome (BBSOAS) is an autosomal dominant neurodevelopmental disorder caused by loss‐of‐function variants in NR2F1 and characterized by visual impairment, developmental delay, and intellectual disability. Here we report 18 new cases, provide additional clinical information for 9 previously reported individuals, and review an additional 27 published cases to present a total of 54 patients. Among these are 22 individuals with point mutations or in‐frame deletions in the DNA‐binding domain (DBD), and 32 individuals with other types of variants including whole‐gene deletions, nonsense and frameshift variants, and point mutations outside the DBD. We corroborate previously described clinical characteristics including developmental delay, intellectual disability, autism spectrum disorder diagnoses/features thereof, cognitive/behavioral anomalies, hypotonia, feeding difficulties, abnormal brain MRI findings, and seizures. We also confirm a vision phenotype that includes optic nerve hypoplasia, optic atrophy, and cortical visual impairment. Additionally, we expand the vision phenotype to include alacrima and manifest latent nystagmus (fusional maldevelopment), and we broaden the behavioral phenotypic spectrum to include a love of music, an unusually good long‐term memory, sleep difficulties, a high pain tolerance, and touch sensitivity. Furthermore, we provide additional evidence for genotype–phenotype correlations, specifically supporting a more severe phenotype associated with DBD variants.  相似文献   
104.
目的:报道1例偶然发现的右侧永久性三叉动脉形态、特点,并进行文献复习。方法:利用显微解剖对此例永久性三叉动脉的起源、走行、分支、分布、与后循环连接关系、以及相关动脉解剖特点等进行了研究。结果:此例永久性三叉动脉与脑膜垂体干共干起源于颈内动脉海绵窦段,于展神经外侧进入后颅窝,分支与基底动脉和小脑上动脉吻合,其终末支之一延续为同侧的小脑下后动脉,此动脉与三叉神经关系密切,分支分布于脑干和小脑。结论:永久性三叉动脉与后循环关系复杂,广泛参与正常脑组织供血。  相似文献   
105.
106.
目的 :介绍一种安全、简便、有效的腰椎间盘手术的局麻方法—脊神经后支阻滞法。方法 :0 .5 %普鲁卡因 10 0ml和 2 %利多卡因 2 0ml混合备用。先在切口处皮内注射 5ml麻药 ,再于开窗侧阻滞 5根脊神经后支主干 (上 3下 2 ) ,麻药用量 3~ 5ml。脊神经后支主干位于横突根部上缘。其体表投影点的确定方法是通过上下棘突连线的上中 1 3交界点作一水平线 ,该线是横突的上缘线的体表投影 ;旁开腰 1棘突 2cm取一点 ;再旁开腰 5棘突 3cm取一点 ;通过这两点作一直线 ,该线与各横线的交点即为各脊神经后支主干部的发出点。结果 :40 63例麻醉效果 :优 72 .2 % ,良 2 4.6% ,中 3 % ,差 0 .2 %。效果差者 ,经静脉使用镇痛镇静类药也取得较好效果。结论 :腰椎间盘手术采用脊神经后支阻滞麻醉经济安全可靠。  相似文献   
107.
An H  Yu Y  Zhang M  Xu H  Qi R  Yan X  Liu S  Wang W  Guo Z  Guo J  Qin Z  Cao X 《Immunology》2002,106(1):38-45
Toll-like receptors (TLR) are sentinel receptors capable of recognizing pathogen-associated molecule patterns (PAMP) such as lipopolysaccharide (LPS) and CpG-containing oligonucleotides (CpG ODN). TLR2 and TLR4 are major receptors for Gram-positive and Gram-negative bacterial cell wall components, respectively. TLR9 is necessary for CpG signalling. LPS or CpG ODN can activate immature dendritic cells (DC) and induce DC maturation characterized by production of cytokines, up-regulation of co-stimulatory molecules, and increased ability to activate T cells. However, little is known regarding the regulation of TLR gene expression in mouse DC. In this study, we investigated the regulation of TLR2, TLR4 and TLR9 gene expression by LPS in murine immature DC. TLR2, TLR4 and TLR9 mRNA were up-regulated following LPS stimulation. The up-regulation of TLR9 expression coincided with significantly increased production of tumour necrosis factor-alpha induced by LPS plus CpG ODN. While inhibition of extracellular signal-related kinase and NF-kappaB activation suppressed the up-regulation of the expression of TLR2, TLR4 and TLR9 mRNA, inhibition of p38 kinase prevented the up-regulation of TLR2 and TLR4 mRNA expression but enhanced the up-regulation of TLR9 expression. These results demonstrated that TLR2, TLR4 and TLR9 gene expression was differently regulated by LPS in mouse immature DC. Up-regulation of TLR2, TLR4 and TLR9 expression by LPS might promote the overall responses of DC to bacteria and help to explain the synergy between LPS and other bacterial products in the induction of cytokine production.  相似文献   
108.
研究单次及长期维持血液透析时尿毒症患者血液流变性改变的影响。结果表明,单次血透后,红细胞比积明显升高,红细胞刚性明显降低;血浆粘度、红细胞聚集指数、Casson粘度、血液屈服应力及低切至高切的全血粘度无明显改变。维持血透患者的红细胞比积、血浆粘度、红细胞聚集指数、Casson粘度、血液屈服应力均无明显改变。进一步研究发现,单次血透后血浆渗透比明显降低.这可能是引起红细胞比积升高、红细胞刚性降低的原因之一。  相似文献   
109.
An HJ  Jeong HJ  Lee EH  Kim YK  Hwang WJ  Yoo SJ  Hong SH  Kim HM 《Inflammation》2004,28(5):263-270
Xanthii Fructus (XF) is an herb widely used in medicine for the treatment of a variety of inflammatory pathologies. In this study, using mouse peritoneal macrophages, we have examined whether XF affects nitric oxide (NO), tumor necrosis factor (TNF)-α, and interleukin (IL)-12p40 production induced by interferon (IFN)-γ and lipopolysaccharide (LPS). XF inhibits IFN-γ and LPS-induced NO production in a dose dependent manner. The decrease in NO synthesis was reflected as a decreased amount of inducible NO synthase protein. Furthermore, we also found that XF inhibits pro-inflammatory cytokine TNF-α production. However, treatment of XF in peritoneal macrophages had no effect on IL-12p40 production. These findings suggest that XF may be used in controlling macrophages-mediated inflammatory diseases.  相似文献   
110.
Infections caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are emerging as a major public health problem. CA-MRSA has been associated previously with skin and soft-tissue infection (SSTI) and with carriage of staphylococcal cassette chromosome mec (SCCmec) type IV and the Panton-Valentine leucocidin (PVL) virulence factor. To assess the clonal distribution of PVL-carrying strains and the association with SSTI in the San Francisco Bay area, we surveyed six collections of S. aureus isolates-671 isolates in all-collected between 1997 and 2002 originating from inpatient and outpatient clinical specimens and from a community-based sampling. Isolates were genotyped by pulsed-field gel electrophoresis, multilocus restriction fragment typing, and multilocus sequence typing and assayed for the PVL virulence factor. The S. aureus populations showed a high proportion of PVL-carrying strains, with frequencies ranging up to 70% in MRSA isolated from jail inmate patients and 69% in MRSA from patients receiving surgical treatment at an outpatient clinic specializing in treating SSTIs. PVL-carrying isolates were identified in nine clonal groups, but 88.5% of the PVL-carrying MRSA isolates belonged to only two clonal groups. These two clonal groups carried the SCCmec type IV resistance determinant and were more likely than other clonal groups to be recovered from SSTI sites than from other sites (P < 0.0001). There is evidence of clonal replacement over the period from 1999 to 2002, with one of these two clonal groups being supplanted by the other.  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