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   5391篇
  免费   1601篇
  国内免费   81篇
耳鼻咽喉   32篇
儿科学   145篇
妇产科学   66篇
基础医学   1641篇
口腔科学   188篇
临床医学   607篇
内科学   503篇
皮肤病学   69篇
神经病学   713篇
特种医学   75篇
外科学   903篇
综合类   657篇
预防医学   514篇
眼科学   80篇
药学   376篇
  5篇
中国医学   150篇
肿瘤学   349篇
  2024年   57篇
  2023年   140篇
  2022年   172篇
  2021年   173篇
  2020年   148篇
  2019年   570篇
  2018年   1021篇
  2017年   100篇
  2016年   147篇
  2015年   103篇
  2014年   336篇
  2013年   315篇
  2012年   214篇
  2011年   214篇
  2010年   152篇
  2009年   167篇
  2008年   128篇
  2007年   106篇
  2006年   96篇
  2005年   283篇
  2004年   118篇
  2003年   73篇
  2002年   69篇
  2001年   44篇
  2000年   219篇
  1999年   213篇
  1998年   193篇
  1997年   94篇
  1996年   103篇
  1995年   50篇
  1994年   128篇
  1993年   158篇
  1992年   230篇
  1991年   62篇
  1990年   150篇
  1989年   41篇
  1988年   119篇
  1987年   81篇
  1986年   59篇
  1985年   54篇
  1984年   49篇
  1983年   20篇
  1982年   40篇
  1981年   9篇
  1980年   7篇
  1979年   6篇
  1978年   5篇
  1977年   5篇
  1976年   11篇
  1974年   11篇
排序方式: 共有7073条查询结果,搜索用时 15 毫秒
1.
目的:探讨改良大骨瓣联合软通道微创介入逐渐减压术治疗重型颅脑损伤的疗效。方法方便选择自2009年12月—2014年11月该院收治的重型颅脑损伤病例70例,随机分为改良组和对照组2组,每组35例,改良组施行改良大骨瓣联合软通道微创介入逐渐减压术,对照组按标准大骨瓣开颅、硬脑膜一次性全切开,对比分析两组的并发症发生率及预后。结果改良组发生迟发性颅内血肿、大面积脑梗塞及弥漫性脑肿胀等并发症9例(25.7%,9/35),预后良好者23例(65.7%,23/35),对照组发生并发症19例(54.3%,19/35),预后良好者14例(40.0%,14/35),两组并发症发生率和预后差异具有统计学意义(P<0.05)。结论改良大骨瓣联合软通道微创介入逐渐减压术治疗重型颅脑损伤,效果良好,显著降低死亡率。  相似文献   
2.
Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo . In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1β (IL-1β) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1β induced a statistically significant inhibition of gel contraction in all fibroblast cell types ( P <0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa.  相似文献   
3.
A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'v) rather than equivalent dioptric power (Fm) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use.  相似文献   
4.
小骨窗术和碎吸术治疗脑出血的临床应用研究   总被引:2,自引:0,他引:2  
目的对比研究颅内血肿小骨窗清除术和颅内血肿(钻孔)碎吸清除术治疗脑出血的疗效。方法87例脑出血患者分为小骨窗组(行颅内血肿小骨窗清除术)、碎吸组(行颅内血肿碎吸清除术)和对照组(行内科保守治疗)。分别比较小骨窗组、碎吸组、保守组治疗前后的GCS评分及3组的GCS评分差。采用t检验、χ2检验和单因素方差分析比较。结果小骨窗组、碎吸组与保守组的GCS评分差比较均有差异(P<0.05);小骨窗组和碎吸组的GCS评分差比较也有差异(P<0.05)。结论小骨窗颅内血肿清除术、碎吸颅内血肿清除术、内科保守疗法在脑出血治疗中均能发挥一定的作用。小骨窗术和碎吸术在治疗中均能提高疗效、加快神经功能恢复,但小骨窗术较碎吸术能更好地发挥疗效、提高病人的生存质量。  相似文献   
5.
The expression of mRNA encoding the inflammatory cytokines interleukin-1α (IL-1α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor α (TNF-α) have been examined in radicular cysts by in situ hybridization. Furthermore, the biological activity of the contents of radicular cysts (RCC) has been assayed by adding extracts of RCC to cultured human gingival fibroblasts (HGFs) and analyzing the culture medium for the release of inflammatory cytokines. In the epithelial layer, keratinocytes expressed all cytokine mRNAs examined at various levels. Basal layer cells expressed mRNA for each cytokine. In the subepithelial granulation tissue of the cysts, fibroblasts and macrophages expressed mRNA for IL-6, IL-8, IL-1β and TNF-α mRNA at varying levels; especially clear expression of TNF-α and IL-1β mRNA was detected on macrophages. The infiltrating lymphoid cells, largely composed of T cells and plasma cells, expressed these cytokine mRNAs, especially those encoding IL-6 and IL-8, at various levels. In vitro analysis indicated dose-dependent release of both IL-6 and IL-8 by HGFs in response to RCC. After heating to 100°C for 10 min, RCC almost completely failed to stimulate IL-6 release from HGFs. Furthermore, anti-IL-1β antibody (neutralization test) did not prevent the stimulation of IL-6 release by RCC. Significant amounts of IL-6 and IL-8 were detected in RCC in two cases, and a trace amount of IL-1β was detected in one case. This study demonstrated the wide expression of mRNA encoding inflammatory cytokines in radicular cyst tissues, and RCC itself was capable of stimulating 1L-6 and 1L-8 production from HGFs.  相似文献   
6.
HIPDM-Single photon emission computed tomography brain imaging was performed during interictal and ictal stages in three patients with complex partial seizures and secondarily generalized tonic-clonic seizures. In all three patients, interictal studies demonstrated decreased regional cerebral perfusion (rCP) and ictal studies showed increased rCP in the epileptogenic region. The demonstration of focal hyperperfusion by SPECT performed during secondarily generalized tonic-clonic seizures suggests that rCP in the epileptic focus remains higher than in other cerebral regions during immediate postictal stages, even in secondarily generalized seizures.  相似文献   
7.
关键影像标记通过指定一组事务处理的定义,将影像检查序列中一帧或多帧关键影像与其对应的注释信息进行关联。本文对该集成模型的角色、事务处理以及相关的DICOM内容进行了分析。  相似文献   
8.
显微锁孔手术治疗脑干及其周围病变   总被引:4,自引:0,他引:4  
目的 将显微锁孔手术应用于脑干及其周围病变的外科治疗,探求以最小的创伤来取得最佳的手术疗效。方法 采用颞下锁孔人路、乳突后锁孔人路、枕下正中锁孔人路,以20mm左右直径的骨窗进行脑干及其周围病变的显微手术治疗。结果 本组16例例病人术后3d内均行MRI或DSA检查,肿瘤或动静脉畸形全切除11例,次全切除3例,部分切除1例,1例小脑后下动脉瘤成功夹闭。术中输血3例。并发脑脊液耳漏1例,硬膜下积液1例,1例术后持续昏迷40d苏醒,无死亡及感染病例。结论 锁孔人路微创技术处理脑干及其周围病变,因其手术创伤小,疗效佳,费用节省,值得临床推广应用。  相似文献   
9.
Here we report the finding of enzymatic activity that specifically cleaves DNA containing 8-hydroxyguanine (oh8Gua) residues in various mammalian cells. To detect this activity, we used a synthetic double-stranded DNA containing a single oh8Gua at a defined position as the substrate, and analyzed the products of enzymatic digestion by polyacrylamide gel electrophoresis. Two cleavage sites near the oh8Gua residue were detected with partially purified fractions from cow brain and rat liver, and also with preparations from all mammalian tissues examined. These results suggest that enzymatic activity for the removal of oh8Gua from DNA is widely distributed in mammalian cells.  相似文献   
10.
A case-control study to evaluate the efficacy of lung cancer screening conducted by us showed that lung cancer screening may reduce the mortality of the disease up to 28%. Assuming this efficacy is unbiased, and that the screening rate is 51.6%, which was observed in the control group in the above study, the number of lung cancer deaths prevented by screening in the study period was calculated to be 47 for males and females combined. In the same study population, screen-detected lung cancer patients (N = 207) in the same study period were followed and the 7-year survival rate (46.9%) was compared to the 5-year survival rate (11.3%) obtained by the Osaka Cancer Registry, in which screen-detected lung cancer patients were only 1.8%. The number of lung cancer deaths prevented by screening, estimated by the difference in the above two survival rates, was 74 (95% confidence interval; 55–93). The number of lung cancer deaths prevented by screening estimated from the case-control study was significantly lower than that estimated from the survival analysis. This indicates that the efficacy of lung cancer screening estimated by the case-control study was within the range that could be explained by the actual long-term survivors among the screen-detected patients in the study population.  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