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   4899篇
  免费   247篇
  国内免费   34篇
耳鼻咽喉   46篇
儿科学   402篇
妇产科学   101篇
基础医学   571篇
口腔科学   95篇
临床医学   535篇
内科学   1192篇
皮肤病学   52篇
神经病学   315篇
特种医学   537篇
外国民族医学   1篇
外科学   463篇
综合类   51篇
一般理论   1篇
预防医学   304篇
眼科学   46篇
药学   213篇
中国医学   7篇
肿瘤学   248篇
  2021年   66篇
  2020年   48篇
  2019年   54篇
  2018年   81篇
  2017年   52篇
  2016年   57篇
  2015年   76篇
  2014年   87篇
  2013年   169篇
  2012年   162篇
  2011年   165篇
  2010年   149篇
  2009年   142篇
  2008年   173篇
  2007年   191篇
  2006年   166篇
  2005年   156篇
  2004年   184篇
  2003年   146篇
  2002年   160篇
  2001年   141篇
  2000年   170篇
  1999年   145篇
  1998年   182篇
  1997年   154篇
  1996年   159篇
  1995年   105篇
  1994年   98篇
  1993年   102篇
  1992年   90篇
  1991年   89篇
  1990年   85篇
  1989年   134篇
  1988年   106篇
  1987年   119篇
  1986年   76篇
  1985年   97篇
  1984年   57篇
  1983年   69篇
  1982年   52篇
  1981年   36篇
  1980年   44篇
  1979年   53篇
  1978年   41篇
  1977年   32篇
  1976年   47篇
  1975年   33篇
  1974年   22篇
  1973年   22篇
  1972年   23篇
排序方式: 共有5180条查询结果,搜索用时 46 毫秒
991.
Background The hemostatic system is complex and evolves continuously since gestation and well into the adult years,in a process known as“developmental hemostasis.”Data sources A comprehensive review was performed after an extensive literature search on PubMed/MEDLINE concerning developmental hemostasis during the neonatal period.Relevant cross references were also included.Results Although part of a system,each component of the hemostatic system evolves differently,with many displaying both quantitative and qualitative age-related differences.This leads to drastic disparities between the coagulation system of neonates and both other children’s and adults’,while still maintaining a generally balanced and physiological hemostasis.The motives behind this process remain to be fully elucidated but may be,at least in part,related to non-hemostatic factors.Conclusions Knowledge regarding“developmental hemostasis”is essential for everyone caring for newborns or even children in general and in this review,we describe each hemostatic system component’s neonatal characteristics and age-related progression as well as explore some of the possible physiological motives behind the process.  相似文献   
992.
No reliable non-invasive glucose monitoring devices are currently available. We implemented a mid-infrared (MIR) photoacoustic (PA) setup to track glucose in vitro in deep epidermal layers, which represents a significant step towards non-invasive in vivo glucose measurements using MIR light. An external-cavity quantum-cascade laser (1010-1095 cm(-1)) and a PA cell of only 78 mm(3) volume were employed to monitor glucose in epidermal skin. Skin samples are characterized by a high water content. Such samples investigated with an open-ended PA cell lead to varying conditions in the PA chamber (i.e., change of light absorption or relative humidity) and cause unstable signals. To circumvent variations in relative humidity and possible water condensation, the PA chamber was constantly ventilated by a 10 sccm N(2) flow. By bringing the epidermal skin samples in contact with aqueous glucose solutions with different concentrations (i.e., 0.1-10 g/dl), the glucose concentration in the skin sample was varied through passive diffusion. The achieved detection limit for glucose in epidermal skin is 100 mg/dl (SNR=1). Although this lies within the human physiological range (30-500 mg/dl) further improvements are necessary to non-invasively monitor glucose levels of diabetes patients. Furthermore spectra of epidermal tissue with and without glucose content have been recorded with the tunable quantum-cascade laser, indicating that epidermal constituents do not impair glucose detection.  相似文献   
993.
The aims of this review were to summarise the various methods of digital colposcopy and to provide an overview of their efficacy. We conducted a literature search and focused on papers that described a technique for colposcopy, other than conventional colposcopy, and compared this with conventional colposcopy and/or histology and included digitalisation of the process. All papers have been classified in one of the following categories: digital imaging and telecolposcopy, spectroscopy, computerised colposcopy, optical coherence tomography and confocal microcolposcopy. Among the most promising developments is spectroscopy, allowing a more or less automated analysis and interpretation of the colposcopic image.  相似文献   
994.
Thirty-eight human immunodeficiency virus-1 (HIV-1)-infected pregnant women were administered tenofovir disoproxil fumarate (TDF; 300 mg)-emtricitabine (FTC; 200 mg) tablets: two at labor initiation and one daily for 7 days postpartum. Maternal, umbilical, and neonatal plasma tenofovir concentrations were measured by high-performance liquid chromatography and analyzed using a population approach. Data were described using a two-compartment model for the mother, an effect compartment linked to maternal circulation for cord, and a neonatal compartment disconnected after delivery. Absorption was greater for women delivering by caesarian section than for those delivering vaginally. The maternal 600 mg TDF administration before delivery produces the same concentrations as 300 mg administration in other adults. If the time elapsed between maternal administration and delivery is >or=12 h, two tablets of TDF-FTC should be readministered. Tenofovir showed good placental transfer (60%). Administering 13 mg/kg of TDF as soon as possible after birth should produce neonatal concentrations comparable with those observed in adults.  相似文献   
995.
996.
997.
The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers, and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant, and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed and sensitive manner.  相似文献   
998.
The value of an implantable ECG monitor (Reveal TM Plus) is reported in a 12 year old child with unexplained syncopal episodes despite extensive investigations. Twenty-seven days after the implantation, ventricular tachycardia at 450/min was recorded at the first recurrence. This case shows that this type of monitoring can be particularly useful when an arrhythmia is thought to be the cause of syncope in a child and the initial investigation is negative.  相似文献   
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