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   1762篇
  免费   140篇
  国内免费   16篇
耳鼻咽喉   12篇
儿科学   25篇
妇产科学   18篇
基础医学   278篇
口腔科学   13篇
临床医学   168篇
内科学   544篇
皮肤病学   35篇
神经病学   172篇
特种医学   50篇
外科学   263篇
综合类   15篇
预防医学   84篇
眼科学   4篇
药学   88篇
中国医学   3篇
肿瘤学   146篇
  2024年   2篇
  2023年   22篇
  2022年   35篇
  2021年   88篇
  2020年   39篇
  2019年   78篇
  2018年   75篇
  2017年   70篇
  2016年   52篇
  2015年   49篇
  2014年   81篇
  2013年   98篇
  2012年   157篇
  2011年   166篇
  2010年   82篇
  2009年   86篇
  2008年   120篇
  2007年   98篇
  2006年   100篇
  2005年   93篇
  2004年   72篇
  2003年   94篇
  2002年   66篇
  2001年   8篇
  2000年   10篇
  1999年   10篇
  1998年   10篇
  1997年   9篇
  1996年   12篇
  1995年   9篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1986年   1篇
  1980年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
排序方式: 共有1918条查询结果,搜索用时 15 毫秒
991.
992.
993.
BACKGROUND: Percutaneous closure of patent foramen ovale (PFO) is generally performed using intra-procedural guidance by transoesophageal (TEE) or intracardiac (ICE) echocardiography. While TEE requires sedation or general anaesthesia, ICE is costly and adds incremental risk, and both imaging modalities lengthen the procedure. METHODS: A total of 825 consecutive patients (age 51 +/- 13 years; 58% male) underwent percutaneous PFO closure solely under fluoroscopic guidance, without intra-procedural echocardiography. The indications for PFO closure were presumed paradoxical embolism in 698 patients (95% cerebral, 5% other locations), an embolic event with concurrent aetiologies in 47, diving in 51, migraine headaches in 13, and other reasons in 16. An atrial septal aneurysm was associated with the PFO in 242 patients (29%). RESULTS: Permanent device implantation failed in two patients (0.2%). There were 18 procedural complications (2.2%), including embolization of the device or parts of it in five patients with successful percutaneous removal in all cases, air embolism with transient symptoms in four patients, pericardial tamponade requiring pericardiocentesis in one patient, a transient ischaemic attack with visual symptoms in one patient, and vascular access site problems in seven patients. There were no long-term sequelae. Contrast TEE at six months showed complete abolition of right-to-left shunt via PFO in 88% of patients, whereas a minimal, moderate or large residual shunt persisted in 7%, 3%, and 2%, respectively. CONCLUSIONS: This study confirms the safety and feasibility of percutaneous PFO closure without intra-procedural echocardiographic guidance in a large cohort of consecutive patients.  相似文献   
994.
Activation of PI3K is among the earliest signaling events observed in T cells after conjugate formation with antigen-presenting cells (APCs). The relevant PI3K catalytic isoform and relative contribution of the TcR and CD28 to PI3K activity at the immune synapse have not been determined unequivocally. Using a quantitative imaging-based assay, we show that the PI3K activity at the T cell-APC contact area is dependent on the p110delta, but not the p110gamma, isoform of PI3K. CD28 enhanced PIP3 production at the T-cell synapse independently of its YMNM PI3K-recruitment motif that instead was required for efficient PKC recruitment. CD28 could partially compensate for the lack of p110delta activity during T-cell activation, which indicates that CD28 and p110delta act in parallel and complementary pathways to activate T cells. Consistent with this, CD28 and p110delta double-deficient mice were severely immune compromised. We therefore suggest that combined pharmaceutic targeting of p110delta activity and CD28 costimulation has potent therapeutic potential.  相似文献   
995.

Background and aims

In patients with chronic hepatitis B (CHB) who have failed on other nucleos(t)ide analogs (NUCs), the combination of entecavir (ETV) plus tenofovir disoproxil fumarate (TDF), two potent agents with non-overlapping resistance profiles, may provide a single rescue regimen.

Methods

In this single-arm, open-label study, 92 CHB patients with a primary non-response, partial response, or virologic breakthrough on their current NUC were switched to ETV (1 mg) plus TDF (300 mg) and treated for 96 weeks.

Results

At baseline, 62 % of patients were HBeAg(+) and mean HBV DNA was 4.4 log10IU/mL. Patients had received ≥1 line of prior NUC therapy, with the latest regimen consisting of monotherapy with ETV (53 %), lamivudine (LVD 22 %), TDF (12 %), adefovir (ADV 4 %), or telbivudine (2 %), or combinations of these agents (7 %); 58 % had evidence of single- or multidrug resistance mutations (LVD 52 %, ETV 26 %; ADV 7 %). Response rates for HBV DNA <50 IU/mL were 76 % (70/92) at week 48 (primary endpoint), and 85 % (78/92) at week 96, including 80 % (16/20) in prior LVD failures, 100 % (4/4) in ADV failures, 82 % (9/11) in TDF failures, and 88 % (42/48) in ETV failures. No treatment-emergent resistance to ETV or ADV was observed. ETV/TDF was well tolerated, with no significant renal or additive toxicities observed.

Conclusions

In NUC-experienced patients who have failed prior NUC therapy, ETV/TDF was well tolerated and effective, achieving virologic suppression through 96 weeks in the majority (85 %), irrespective of prior NUC exposure, without occurrence of treatment-emergent resistance to either agent.
  相似文献   
996.
OBJECTIVE: The efficacy of anti-tumour necrosis factor-alpha (TNF-alpha) therapies in rheumatoid arthritis (RA) has been mainly attributed to TNF-alpha neutralisation. Other mechanism as immune cell apoptosis, which is impaired in RA, may also be induced by anti-TNF-alpha therapies. The aim of our study was to investigate whether TNF-alpha inhibitors could induce apoptosis in vitro of the peripheral blood lymphocytes of RA patients. METHODS: Peripheral blood mononuclear cells (PBMC) isolated from 24 patients with RA and 18 healthy donors were incubated with anti-TNF-alpha agents, infliximab or etanercept, in comparison with no agent and including an isotypic control, for 48 hours. Apoptosis was detected and quantified by annexin V labelling of phosphatidylserine externalization using cytofluorometric analysis and compared with PBMC production TNF-alpha in vitro. RESULTS: In healthy donors, induced apoptosis was observed in 0.3% to 3.8% of lymphocytes with both therapies. In RA patients the treatment induced lymphocyte apoptosis in 17 of 24 patients with a percentage of annexin V-positive lymphocytes ranging from 0.1% to 25%. Among these 17 RA patients, a significant in vitro lymphocyte apoptosis (> 4%) was observed in 11 patients (46%) compared with healthy donors (p < 0.01). The variability of the response to anti-TNF-alpha within the RA population was not dependent on TNF-alpha synthesis or disease activity. CONCLUSION: In vitro induction of lymphocyte apoptosis by anti-TNF-alpha was observed in a subgroup of RA patients. Based on these data, it would be of interest to further study the interindividual variations of sensitivity to apoptosis induced by TNF alpha inhibitors in relation to treatment efficacy or resistance observed in RA patients.  相似文献   
997.
998.
999.
1000.
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