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   31203篇
  免费   3082篇
  国内免费   1193篇
耳鼻咽喉   117篇
儿科学   165篇
妇产科学   188篇
基础医学   2241篇
口腔科学   759篇
临床医学   3515篇
内科学   1382篇
皮肤病学   241篇
神经病学   745篇
特种医学   755篇
外科学   1800篇
综合类   7353篇
现状与发展   2篇
预防医学   3695篇
眼科学   267篇
药学   6151篇
  175篇
中国医学   5432篇
肿瘤学   495篇
  2024年   71篇
  2023年   434篇
  2022年   901篇
  2021年   1423篇
  2020年   1281篇
  2019年   748篇
  2018年   704篇
  2017年   1015篇
  2016年   1134篇
  2015年   1164篇
  2014年   2302篇
  2013年   2299篇
  2012年   2385篇
  2011年   2496篇
  2010年   1895篇
  2009年   1531篇
  2008年   1566篇
  2007年   1813篇
  2006年   1364篇
  2005年   1161篇
  2004年   977篇
  2003年   771篇
  2002年   662篇
  2001年   593篇
  2000年   511篇
  1999年   459篇
  1998年   378篇
  1997年   310篇
  1996年   319篇
  1995年   312篇
  1994年   298篇
  1993年   284篇
  1992年   245篇
  1991年   218篇
  1990年   194篇
  1989年   180篇
  1988年   168篇
  1987年   151篇
  1986年   143篇
  1985年   151篇
  1984年   88篇
  1983年   54篇
  1982年   93篇
  1981年   44篇
  1980年   35篇
  1979年   30篇
  1978年   29篇
  1977年   20篇
  1976年   24篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
This project aimed to enhance clinical education preparation in a family nurse practitioner graduate program in rural central Appalachian by providing a psychomotor skills-based simulation with the use of the defusing, discovering, and deepening (3D) debriefing method. The students were surveyed after graduation to determine effectiveness. Program outcomes to measure readiness to practice were graduation, employment, and certification rates. The postgraduation surveys indicated the simulation contributed to an increase in psychomotor skill performance, practicing safe patient care, and making independent decisions in practice. Common themes emerged of feeling “prepared for practice” and being “more marketable” with the procedural skills learned in the simulation.  相似文献   
12.
目的:通过检索《针灸大成》中与气海穴治疗作用相关的文献条文,总结气海穴在治疗各系统疾病中运用频次较高的疾病及其配穴规律,为临床针灸对气海穴的使用提供理论支持。方法:以《中华医典》(第五版)中《针灸大成》作为文献检索来源,将气海穴及气海穴的别称“脖胦”“下肓”“丹田”“肓之原”“肓原”“下言”和“气泽”为检索词,用计算机检索工具及人工检索相结合的方法检索符合要求的文献条文,通过建立本研究的数据库,频次分析、条形统计图比较分析等方法,总结出气海穴在治疗各系统疾病中的运用频次及其配穴规律。结果:在《针灸大成》所涉及的条文中,气海穴尤善治疗内科疾病,在治疗内科疾病中排名前3位的是脾胃系病症、气血津液疾病、肾系病症和妇科疾病,气海穴配穴习惯为上下配穴法,同名经配穴法,以及前后配穴法,其中主要为前后配穴法和同名经配穴法。结论:气海穴《针灸大成》中单穴应用占比最高,而在气海穴众多配穴中,运用了本经配穴法、上下配穴法、前后配穴法,配穴归经主要来自任脉和足太阳膀胱经。同名经配穴法,同气相求,可增加疗效;与气海穴配伍较多的足太阳膀胱经以背腧穴为主,此为前后配穴法,亦称腹背阴阳配穴法,腹部为阴,腰背为阳,前后配穴法可起到“从阳引阴”亦可“从阴引阳”的作用,以达到调节阴阳,调和脏法,调畅经络的目的。  相似文献   
13.
14.
PurposeAlthough many studies have examined the efficiency of various protective devices for reducing the dose of radiation exposure to physicians during interventional pain procedures, no study has compared the protective effect of these devices when they are used in combination. The purpose of this prospective experimental study was to determine the best combination of radiation-shielding devices.Materials and MethodsUsing anthropomorphic phantoms of a physician and patient, we measured the radiation protection efficiency (RPE) of each of the following protection methods and in combination during C-arm–guided simulated lumbar epidural injection: (a) personal protective equipment (PPE), (b) bedside curtain shield (Curtain), (c) x-ray tube filter (Filter), and (d) fluoroscopic collimation method (Collimation). We measured exposure doses using personal electronic dosimeters at the eye, thyroid, and gonad levels for 1 minute. Each experiment was repeated 15 times.ResultsThe radiation exposure dose and RPE with the best single-, double-, and triple-protection methods were as follows: PPE for the single-protection method (11.82 μSv/min, 80.04%), PPE + Collimation for the double-combination method (4.68 μSv/min, 92.09%), and PPE + Collimation + Curtain for the triple-combination method (3.08 μSv/min, 93.39%). Additionally, PPE + Collimation + Curtain + Filter for the quadruple-combination method resulted in a radiation exposure and RPE of 2.91 μSv/min and 93.61%, respectively, compared with nonprotection.ConclusionsThe best single-, double-, and triple-protection method was PPE, PPE + Collimation, and PPE + Collimation + Curtain, respectively. While preparing protective equipment, we recommend prioritizing equipment in this order.  相似文献   
15.
A high-order, well-balanced, positivity-preserving quasi-Lagrange moving mesh DG method is presented for the shallow water equations with non-flat bottom topography. The well-balance property is crucial to the ability of a scheme to simulate perturbation waves over the lake-at-rest steady state such as waves on a lake or tsunami waves in the deep ocean. The method combines a quasi-Lagrange moving mesh DG method, a hydrostatic reconstruction technique, and a change of unknown variables. The strategies in the use of slope limiting, positivity-preservation limiting, and change of variables to ensure the well-balance and positivity-preserving properties are discussed. Compared to rezoning-type methods, the current method treats mesh movement continuously in time and has the advantages that it does not need to interpolate flow variables from the old mesh to the new one and places no constraint for the choice of a update scheme for the bottom topography on the new mesh. A selection of one- and two-dimensional examples are presented to demonstrate the well-balance property, positivity preservation, and high-order accuracy of the method and its ability to adapt the mesh according to features in the flow and bottom topography.  相似文献   
16.
In this paper, we consider the numerics of the dispersion-managed Korteweg-de Vries (DM-KdV) equation for describing wave propagations in inhomogeneous media. The DM-KdV equation contains a variable dispersion map with discontinuity, which makes the solution non-smooth in time. We formally analyze the convergence order reduction problems of some popular numerical methods including finite difference and time-splitting for solving the DM-KdV equation, where a necessary constraint on the time step has been identified. Then, two exponential-type dispersion-map integrators up to second order accuracy are derived, which are efficiently incorporated with the Fourier pseudospectral discretization in space, and they can converge regardless of the discontinuity and the step size. Numerical comparisons show the advantage of the proposed methods with the application to solitary wave dynamics and extension to the fast & strong dispersion-management regime.  相似文献   
17.
目的 系统评价德尔菲法在中医临床证候应用中的应用现状,为后续规范与完善证候研究方法提供参考。方法 计算机检索五大数据库关于中医临床证候研究中应用德尔菲法的研究,检索时限自建库至2021年6月1日,由两名研究人员独立进行文献筛选、质量评估和资料提取,对质量A级和B级的研究进行分析。结果 经过质量评价共纳入201篇文献,其中原始研究199篇,方法学研究9篇。研究方向包括候分布特点、证候诊断标准、单一证候研究、证候要素研究、证候变化规律等八类。192篇文献对德尔菲法具体实施进行报道。结论 中医临床证候研究中德尔菲法应用整体较为科学,但在证候研究细节实施尚有不足,有待形成符合中医证候特色的德尔菲法标准规范临床应用。  相似文献   
18.
目的:探讨改进Seldinger法经皮穿刺腹膜透析置管术在终末期肾病患者中的应用效果。方法:选取2019年12月~2020年12月于本院进行腹膜透析置管术的终末期肾病患者61例,随机分为观察组(31例)和对照组(30例),对照组患者采用常规开腹手术置管,观察组采用改进Seldinger法置管,比较两组患者完成置管手术的相关指标(手术时间、术后排气时间、切口长度、住院时间),术后3d、1个月患者并发症发生情况。结果:较对照组,观察组手术时间、术后排气时间均更短,腹部切口长度更短(P<0.05),两组患者住院时间比较(P>0.05),观察组穿刺成功率明显高于对照组(100.00%,80.00%,χ2=6.88,P=0.01)。较对照组,观察组患者术后3d并发症发生率明显低于对照组(22.58%,50.00%,χ2=4.97,P=0.03),观察组患者术后1个月并发症发生率明显低于对照组(19.35%,53.33%,χ2=7.05,P=0.01)。结论:对终末期肾病患者运用改进Seldinger法经皮穿刺腹膜透析置管术进行置管可有效缩短手术时间和术后排气时间,创口较小,患者术后早期、远期并发症较少,临床应用效果较好。  相似文献   
19.
This randomized controlled trial evaluated the effect of a 5-week daily skin-to-skin contact (SSC) intervention between mothers and their full-term infants, compared with care-as-usual, on exclusive and continued breastfeeding duration during the first post-natal year. Healthy pregnant women (n = 116) from a community sample were enrolled and randomly allocated to the SSC or care-as-usual condition. SSC mothers were requested to provide one daily hour of SSC for the first five post-natal weeks. Twelve months post-partum, mothers indicated the number of exclusive and continued breastfeeding months. Multiple regression analyses were conducted using intention-to-treat, per-protocol and exploratory dose–response frameworks. In intention-to-treat analyses, exclusive and continued breastfeeding duration was not different between groups (exclusive: 3.61 ± 1.99 vs. 3.16 ± 1.77 months; adjusted mean difference 0.28, 95% confidence interval [CI] ?0.33 to 0.89; p = 0.36; continued: 7.98 ± 4.20 vs. 6.75 ± 4.06 months; adjusted mean difference 0.81, 95% CI ?0.46 to 2.08; p = 0.21). In per-protocol analyses, exclusive and continued breastfeeding duration was longer for SSC than care-as-usual dyads (exclusive: 4.89 ± 1.26 vs. 3.25 ± 1.80 months; adjusted mean difference 1.28, 95% CI 0.31–2.24; p = 0.01; continued: 10.81 ± 1.97 vs. 6.98 ± 4.08 months; adjusted mean difference 2.33, 95% CI 0.13–4.54; p = 0.04). Exploratory dose–response effects indicated that more SSC hours predicted longer exclusive and continued breastfeeding duration. This study demonstrates that for the total group, the 5-week daily SSC intervention did not extend exclusive and continued breastfeeding duration. However, for mothers performing a regular daily hour of SSC, this simple and accessible intervention may extend exclusive and continued breastfeeding duration by months. Future studies are required to confirm these promising findings. Trial registration: Netherlands Trial Register (NTR5697).  相似文献   
20.
Attenuation coefficient estimation has the potential to be a useful tool for placental tissue characterization. A current challenge is the presence of inhomogeneities in biological tissue that result in a large variance in the attenuation coefficient estimate (ACE), restricting its clinical utility. In this work, we propose a new Attenuation Estimation Region Of Interest (AEROI) selection method for computing the ACE based on the (i) envelope signal-to-noise ratio deviation and (ii) coefficient of variation of the transmit pulse bandwidth. The method was first validated on a tissue-mimicking phantom, for which an 18%–21% reduction in the standard deviation of ACE and a 14%–24% reduction in the ACE error, expressed as a percentage of reported ACE, were obtained. A study on 59 post-delivery clinically normal placentas was then performed. The proposed AEROI selection method reduced the intra-subject standard deviation of ACE from 0.72 to 0.39 dB/cm/MHz. The measured ACE of 59 placentas was 0.77 ± 0.37 dB/cm/MHz, which establishes a baseline for future studies on placental tissue characterization.  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