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   12431篇
  免费   768篇
  国内免费   323篇
耳鼻咽喉   67篇
儿科学   179篇
妇产科学   211篇
基础医学   2415篇
口腔科学   274篇
临床医学   1425篇
内科学   1427篇
皮肤病学   216篇
神经病学   743篇
特种医学   298篇
外国民族医学   5篇
外科学   1103篇
综合类   1620篇
预防医学   812篇
眼科学   146篇
药学   1658篇
  5篇
中国医学   295篇
肿瘤学   623篇
  2024年   15篇
  2023年   123篇
  2022年   301篇
  2021年   412篇
  2020年   329篇
  2019年   307篇
  2018年   326篇
  2017年   314篇
  2016年   372篇
  2015年   368篇
  2014年   703篇
  2013年   798篇
  2012年   771篇
  2011年   802篇
  2010年   671篇
  2009年   615篇
  2008年   598篇
  2007年   621篇
  2006年   509篇
  2005年   523篇
  2004年   426篇
  2003年   399篇
  2002年   320篇
  2001年   240篇
  2000年   220篇
  1999年   212篇
  1998年   196篇
  1997年   206篇
  1996年   205篇
  1995年   162篇
  1994年   149篇
  1993年   126篇
  1992年   128篇
  1991年   126篇
  1990年   88篇
  1989年   98篇
  1988年   77篇
  1987年   70篇
  1986年   52篇
  1985年   111篇
  1984年   111篇
  1983年   67篇
  1982年   68篇
  1981年   37篇
  1980年   36篇
  1979年   17篇
  1978年   25篇
  1977年   13篇
  1976年   15篇
  1972年   10篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
目的 分析微滴式数字PCR(droplet digital PCR, ddPCR)和实时荧光定量PCR(quantitative real-time PCR,qPCR)的核酸检测结果,比较两种方法检测各类样本的差异性,为改进新型冠状病毒核酸检测方案提供数据支持。 方法 利用ddPCR和qPCR技术对已经确诊的3例新型冠状病毒肺炎患者发病不同时间的全血、尿液、粪便共22份标本进行新型冠状病毒核酸检测。 结果 两种方法对人保守区域基因扩增结果一致:全血标本信号最强,尿液次之,粪便最少;ddPCR在1份全血,1份尿液,5份粪便中检出ORF-1ab和N基因的阳性微滴,qPCR仅在3份粪便中检出上述基因,漏检的3个标本基因拷贝数平均浓度为128 copies/ml;ddPCR在发病<5、5~15、>15 d的各类标本中都有检出,qPCR检出以中晚期为主;重症病例用ddPCR均可测到阳性微滴,qPCR检测的各类标本均为阴性;轻症病例的各类标本中qPCR只有粪便核酸检测阳性,ddPCR检出率高于qPCR。 结论 ddPCR可以有效克服qPCR 灵敏度不足的难题,是对qPCR 的有益补充,尤其是针对病毒载量比较低的血液、尿液和可疑的粪便或肛拭子标本,适用于早期感染的判断及患者治愈后出院诊断。  相似文献   
3.
4.
5.

Objective

To assay peripheral inter-ictal cytokine serum levels and possible relations with non-invasive vagus nerve stimulation (nVNS) responsiveness in migraineurs.

Methods

This double-blinded, sham-controlled study enrolled 48 subjects and measured headache severity, frequency [headache days/month, number of total and mild/moderate/severe classified attacks/month], functional state [sleep, mood, body weight, migraine-associated disability] and serum levels of inflammatory markers [inter-ictal] using enzyme-linked immunoassays at baseline and after 2 months of adjunctive nVNS compared to sham stimulation and suitably matched controls.

Results

No significant differences were observed at baseline and after 2 months for headache severity, total attacks/month, headache days/month and functional outcome [sleep, mood, disability] between verum and sham nVNS. However, the number of severe attacks/month significantly decreased in the verum nVNS group and circulating pro-inflammatory IL-1β was elevated significantly in the sham group compared to nVNS. Levels of anti-inflammatory IL-10 were significantly higher at baseline in both groups compared to healthy controls, but not at 2 months follow-up [p?<?0.05]. Concentrations of high-mobility group box-1 (HMGB-1), IL-6, tumor-necrosis factor-α (TNF-α), leptin, adiponectin, ghrelin remained unchanged [p?>?0.05]. No severe device-/stimulation-related adverse events occurred.

Conclusion

2 months of adjunctive cervical nVNS significantly declined the number of severe attacks/month. Pro-inflammatory IL-1β plasma levels [inter-ictal] were higher in sham-treated migraine patients compared to verum nVNS. However, pro- [IL-6, HMGB-1, TNF-α, leptin] and anti-inflammatory [IL-10, adiponectin, ghrelin] mediators did not differ statistically. Profiling of neuroinflammatory circuits in migraine to predict nVNS responsiveness remains an experimental approach, which may be biased by pre-analytic variables warranting large-scale biobank-based systematic investigations [omics].  相似文献   
6.
IntroductionThe purpose of this national study was to audit the weight-bearing practice of orthopaedic services in the National Health Service (NHS) in the treatment of operatively and non-operatively treated ankle fractures.MethodsA multicentre prospective two-week audit of all adult ankle fractures was conducted between July 3rd 2017 and July 17th 2017. Fractures were classified using the AO/OTA classification. Fractures fixed with syndesmosis screws or unstable fractures (>1 malleolus fractured or talar shift present) treated conservatively were excluded. No outcome data were collected. In line with NICE (The National Institute for Health and Care Excellence) criteria, “early” weight-bearing was defined as unrestricted weight-bearing on the affected leg within 3 weeks of injury or surgery and “delayed” weight-bearing as unrestricted weight-bearing permitted after 3 weeks.Results251 collaborators from 81 NHS hospitals collected data: 531 patients were managed non-operatively and 276 operatively. The mean age was 52.6 years and 50.5 respectively. 81% of non-operatively managed patients were instructed for early weight-bearing as recommended by NICE. In contrast, only 21% of operatively managed patients were instructed for early weight-bearing.DiscussionThe majority of patients with uni-malleolar ankle fractures which are managed non-operatively are treated in accordance with NICE guidance. There is notable variability amongst and within NHS hospitals in the weight-bearing instructions given to patients with operatively managed ankle fractures.ConclusionThis study demonstrates community equipoise and suggests that the randomized study to determine the most effective strategy for postoperative weight-bearing in ankle fractures described in the NICE research recommendation is feasible.  相似文献   
7.
BackgroundCriteria for delayed ejaculation (DE) rely on a long ejaculation latency (EL) time, lack of control/advancement regarding ejaculation, and associated bother/distress; yet, few studies have investigated these criteria in men who indicate the desire to ejaculate sooner during partnered sex.AimTo help standardize criteria for DE by better understanding characteristics of men who desire to ejaculate sooner during partnered sex in terms of their EL, reported ejaculatory control, and level of bother/distress, as well as their perceptions of typical and ideal ELs for men in general and of ELs for men with premature ejaculation (PE).MethodsA total of 572 men recruited through social media responded to an online survey regarding their EL, as well as typical, ideal, and PE ELs of men in general. They also rated (i) their ability to control and/or advance ejaculation and (ii) their level of associated bother/distress. 4 comparison groups were then established: men with probable DE (with [DE1] and without [DE2] ejaculatory control issues), a reference group with no ejaculatory disorders, and men who identified as having PE.OutcomesTo demonstrate differences in EL, ejaculatory control, and bother/distress between men with delayed ejaculation and the control and PE reference groups.ResultsELs for men with probable DE were twice as long as those with no ejaculatory disorders. When probable DE men were further subdivided into DE2 and DE1, differences were greater for the DE2 group. DE2 men also differed significantly from the reference group on ejaculatory control/advancement but not on bother/distress. Both DE and reference groups differed from the PE group.Clinical ImplicationsUsing both EL and ejaculatory control are useful in distinguishing men with delayed ejaculation from men without delayed ejaculation.Strengths & LimitationsA sizable sample drawn from a multinational population powered the study, whereas the use of social media for recruitment limited the generalizability of findings.ConclusionBoth EL and ejaculatory control differentiate men with probable DE from a control reference group having no ejaculatory disorders. Differences in bother/distress did not emerge as significant. Implications for diagnosing men with DE are presented.Rowland DL, Cote-Leger P. Moving Toward Empirically Based Standardization in the Diagnosis of Delayed Ejaculation. J Sex Med 2020;17:1896–1902.  相似文献   
8.
IntroductionLymph node yield (LNY) in neck dissection has been identified as a prognostic factor in oral cavity cancer. The purpose of this study was to investigate the impact of additional use of optical imaging on LNY in therapeutic ND in oral cancer.MethodsConsecutive patients with oral squamous cell carcinoma with clinical neck metastasis planned for primary tumor resection were randomized to conventional neck dissection or near-infrared fluorescence (NIRF)-guided neck dissection, respectively. In the intervention group, patients were injected with ICG-Nanocoll prior to surgery. Intraoperatively, an optical hand-held camera system was used for lymph node identification. Also, NIRF imaging of the neck specimen was performed, and optical signals were pinned with needle markings to guide the pathological examination. The endpoint of the study was LNY per neck side in levels Ib-III.Results31 patients were included with 18 neck sides in the control group and 18 neck sides in the intervention group for evaluation. During NIRF-guided ND, individual lymph nodes could be identified by a bright fluorescent signal and individual tumor-related drainage patterns could be observed in the neck. The LNY in the intervention group was significantly higher compared to the control group (p = 0.032) with a mean of 24 LN (range: 12–33 LN in levels Ib-III compared to 18 LN (range: 10–36 LN) in the control group, respectively.ConclusionsNIRF-guided ND significantly improved the nodal yield compared to the control group. Intraoperative real-time optical imaging enabled direct visualization of tumor-related drainage patterns within the neck lymphatics.  相似文献   
9.
目的 探究下颌磨牙区即拔即种的临床疗效。方法 选取2017年1月至2019年1月江门市口腔医院收治的60例需进行下颌磨牙区种植的患者随机分为A、B组,A组给予即拔即种,B组给予延期种植,比较两组留存率、浅蝶形骨吸收率、种植12个月后PIS指标及满意度进行评价。结果 随访12个月两组留存率均为100%,浅碟形骨吸收率A组前磨牙为16.67%、磨牙为22.22%,B组前磨牙为10.00%、磨牙为25.00%,差异均无统计学意义(P>0.05),A组植入30个种植体,60个牙间乳头,其中3度29个、2度24个、1度7个,B组植入30个种植体,60个牙间乳头,其中3度14个、2度24个、1度22个,A组牙间乳头PIS指标优于B组,且A组牙间乳头PIS评分(2.36±0.52)较B组(1.87±0.48)显著提高,差异均具有统计学意义(P<0.05),A组对治疗效果满意率为93.33%较B组66.67%显著提高,差异具有统计学意义(P<0.05)。结论 对于下颌磨牙区缺牙患者可采取即拔即种的方法修复,缩短缺牙时间,促进咬合和咀嚼功能恢复,舒适且美观,提高患者的满意度,值得在临床上推广。  相似文献   
10.
目的探讨极速实时荧光聚合酶链反应(polymerase chain reaction,PCR)、实时荧光PCR、酶联免疫吸附测定(enzyme-linked immunosorbent assay,ELISA)和胶体金免疫层析法(gold immunochromatography assay,GICA)4种方法检测新型布尼亚病毒的特异度和灵敏度,为发热伴血小板减少综合征的早期诊断提供依据。方法采集2017年6月1日至9月30日山东大学附属济南市传染病医院86例临床诊断为发热伴血小板减少综合征患者的血清样本,分别应用极速实时荧光PCR、实时荧光PCR、ELISA和GICA 4种方法进行检测。统计学分析采用χ^2检验。结果86份患者血清标本中,极速实时荧光PCR、实时荧光PCR、IgM-ELISA、IgG-ELISA、IgM-GICA、IgG-GICA的新型布尼亚病毒阳性分别为82份(95.34%)、79份(91.86%)、41份(47.67%)、8份(9.3%)、19份(22.09%)和3份(3.49%)。极速实时荧光PCR特异度为100%,灵敏度达到1×103拷贝/mL,3次重复扩增试验显示其Ct值变异系数均<2%。在发热伴血小板减少综合征进展的1期、2期、3期病程中,极速实时荧光PCR的阳性检出率为41份(97.62%)、34份(94.44%)、7份(87.50%),实时荧光PCR的阳性检出率为39份(92.86%)、33份(91.67%)、7份(87.50%),在1期和2期两个病程,极速实时荧光PCR阳性检出率略高;IgM-ELISA阳性检出率从1期(28.57%)到3期(87.50%)显著增高,2期、3期与1期相比,差异均有统计学意义(χ^2=8.347、7.561,均P<0.01);IgM-GICA的阳性检出率从1期(14.29%)到2期(33.33%)也有增高,差异有统计学意义(χ^2=3.962,P<0.05),但与其他方法相比,其检出率偏低。1期,实时荧光PCR阳性检出率显著高于ELISA(IgM和IgG)和GICA(IgM和IgG),差异均有统计学意义(χ^2=33.740、55.080、49.010、64.340,均P<0.01)。2期,实时荧光PCR的阳性检出率高于ELISA(IgM和IgG)和GICA(IgM和IgG),差异均有统计学意义(χ^2=7.700、46.720、23.700、50.630,均P<0.01)。3期,极速实时荧光PCR、实时荧光PCR和IgM-ELISA表现出同样高的阳性检出率,远高于IgG-ELISA和GICA(IgM和IgG)。实时荧光PCR阳性检出率和IgG-ELISA、IgM-GICA、IgG-GICA之间差异均有统计学意义(均χ^2=6.250,P<0.05)。结论极速实时荧光PCR在新型布尼亚病毒的早期检测中有更高的灵敏度和特异度,且重复性好、稳定度高,与传统实时荧光PCR相比大大缩短了扩增时间,对发热伴血小板减少综合征的早期快速诊断具有重要价值。  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