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   13138篇
  免费   829篇
  国内免费   204篇
耳鼻咽喉   54篇
儿科学   108篇
妇产科学   58篇
基础医学   1394篇
口腔科学   265篇
临床医学   1129篇
内科学   1993篇
皮肤病学   248篇
神经病学   2512篇
特种医学   456篇
外国民族医学   1篇
外科学   919篇
综合类   1258篇
预防医学   1783篇
眼科学   266篇
药学   1060篇
  5篇
中国医学   446篇
肿瘤学   216篇
  2024年   17篇
  2023年   316篇
  2022年   419篇
  2021年   659篇
  2020年   615篇
  2019年   682篇
  2018年   571篇
  2017年   369篇
  2016年   370篇
  2015年   344篇
  2014年   842篇
  2013年   700篇
  2012年   680篇
  2011年   755篇
  2010年   621篇
  2009年   574篇
  2008年   568篇
  2007年   571篇
  2006年   462篇
  2005年   357篇
  2004年   313篇
  2003年   293篇
  2002年   248篇
  2001年   212篇
  2000年   182篇
  1999年   166篇
  1998年   150篇
  1997年   125篇
  1996年   124篇
  1995年   122篇
  1994年   123篇
  1993年   114篇
  1992年   106篇
  1991年   114篇
  1990年   114篇
  1989年   96篇
  1988年   97篇
  1987年   97篇
  1986年   109篇
  1985年   175篇
  1984年   129篇
  1983年   102篇
  1982年   80篇
  1981年   78篇
  1980年   56篇
  1979年   47篇
  1978年   20篇
  1977年   33篇
  1976年   19篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
71.
72.
沙苑子本草考证   总被引:1,自引:0,他引:1  
张婷婷  柯创  秦路平  吴建军 《中草药》2020,51(16):4348-4354
沙苑子为我国常用中药,药用历史悠久。通过查阅本草文献,对沙苑子名称、基原、功效、产地及伪品5个方面进行考证,得知其名称演变大致经过"白蒺藜""沙苑蒺藜""沙苑子"3个阶段;历代本草记载沙苑子基原为扁茎黄芪的干燥成熟种子,古今应用品种基本一致;沙苑子补肾固精功效的记载自宋《本草衍义》起逐渐清晰明确;沙苑子道地产区自宋时起为陕西沙苑,明清时期产地逐渐转到陕西潼关、山西等地,建国后以陕西省为主向北扩散,以陕西潼关为佳;沙苑子建国前有马薸子、色微绿伪品及紫云英子等混伪品,建国后有紫云英、猪屎豆、华黄芪和直立黄芪的种子等混伪品。为沙苑子正本清源,并为其进一步深入开发提供参考。  相似文献   
73.
《The ocular surface》2020,18(4):926-935
PurposeTo visualize and quantify vascular networks in individuals with ocular surface squamous neoplasia (OSSN) through optical coherence tomography angiography (OCTA).MethodCross-sectional study of OSSN patients. Vascular networks were measured by OCTA in the epithelium and sub-epithelial space in the tumors, adjacent tissue, and in the contralateral eye. Vessel area density (VAD, percent of blood vessels within 2.14 mm2), was calculated for each location. Total tumor density (TTD, percent of blood vessels within the entire tumor) was calculated. VAD was assessed separately for corneal and conjunctival locations and compared.ResultsFifteen patients with OSSN were included. The mean age was 61 ± 12 years and the majority were male (80%). The mean tumor area, volume, depth, and TTD were 28.0 ± 9.0 mm2 (range, 10.9–39.7), 9.1 ± 4.1 mm3 (range, 3.4–18.8), 334 ± 125 μm (range, 177–571), and 33.2% ± 11.0% (range, 18.7–58.8), respectively. The VAD was highest within the tumor (28.9% ± 8.7%) followed by the adjacent sub-epithelial tissue and the tissue underneath the conjunctival component of tumor. These densities were higher than the VAD in the tissues of the non-involved eye (all P < 0.05). The VAD within conjunctival component of tumor was significantly higher than those with corneal component (29.8% ± 9.5% vs. 21.1% ± 5.5%, p = 0.006). The VAD under conjunctival tumor was also significantly higher than under corneal component (24.1% ± 7.8% vs. 17.0% ± 6.1%, p = 0.024).ConclusionsOCTA imaging allowed for visualization and quantification of vessel structure and density within, under, and surrounding OSSN.  相似文献   
74.
75.
目的:研究大鼠腹侧被盖区(VTA)多巴胺能神经元是否介导食欲素(orexin)的促进全麻后觉醒效应。方法:将兴奋性光遗传病毒注射至Hcrt-cre大鼠的orexin阳性神经元所在的下丘脑外侧穹隆周区(PeFLH),同时在VTA区注射抑制性化学遗传病毒及带有酪氨酸羟化酶(TH)-cre的混合病毒抑制多巴胺能神经元,并在VTA区植入光纤。观察通过化学遗传抑制VTA区多巴胺能神经元后,光遗传兴奋VTA区的orexin阳性神经投射终末是否仍能引起促进异氟醚麻醉后觉醒的效应。结果:与对照组相比,用化学遗传技术预先抑制VTA区多巴胺能神经元,阻断了光遗传兴奋VTA区orexin阳性神经投射终末所产生的缩短大鼠1.4%异氟醚麻醉后觉醒时间的作用;并阻断了光遗传兴奋VTA区orexin阳性神经投射终末所产生的降低大鼠1.4%异氟醚麻醉中脑电图爆发抑制率(BSR)效应。用Fos染色法验证了化学遗传法抑制多巴胺能神经元的可靠性。结论:抑制VTA区的多巴胺能神经元能够阻断兴奋大鼠VTA区orexin阳性神经末梢所产生的促进大鼠异氟醚后觉醒的效应,提示VTA区的多巴胺神经神经元介导了orexin调控VTA区产生的促进觉醒效应。  相似文献   
76.
Prior studies in the Child Health and Development Studies (CHDS) found in utero exposure to the pesticide, dichlorodiphenyltrichloroethane (DDT), increased breast cancer risk by age 52. Mammographic density is considered a primary risk factor for breast cancer. We conducted a study of 309 daughters from the CHDS to examine in utero DDT exposure and mammographic density in midlife. Among daughters with high (>75th percentile) exposure to p,p’-Dichlorodiphenyldichloroethylene (DDE), p,p’-DDT was significantly correlated with increased dense area and percent density regardless of her body mass in midlife. In the subset of women with lower (<75th percentile) p,p-DDE, p,p’-DDT was associated with increased non-dense breast area. This was explained by adjustment for midlife BMI suggesting that p,p’-DDT may be obesogenic. In aggregate our findings indicate that early life p,p’-DDT exposure impacts breast density in a complex way that depends on the hosts biological ability to sequester and process DDT and levels of exposure.  相似文献   
77.
78.
《Radiography》2020,26(4):e207-e213
IntroductionAustralian X-ray operators (XROs) are health workers qualified with a limited radiography licence to perform basic radiography examinations in rural areas of Australia. However, no previous study explored Western Australian (WA) XROs' radiography practice. The purpose of this study was to investigate WA XROs’ self-perceived competence in the general radiography practice, and barriers and facilitators to their competence for determination of appropriate strategies to improve quality and safety of the radiographic service provided by them.MethodsInstitutional review board approval and informed consent from participants were obtained. Interviews were conducted with the WA XROs to obtain demographic information and identify their self-perceived competence in the general radiography practice, and the barriers and facilitators to their competence. A thematic analysis was used to analyse the interview data.ResultsA total of nine interviews were conducted (eight nurses and one paramedic). Participants indicated that they felt highly competent in patient care in radiography and adequately competent in the production of diagnostically acceptable images. The self-perceived barriers include overload of responsibilities, a lack of continuing professional development, and inadequacy of communication, support and XRO courses. The facilitators, post-qualification/course training, support in undertaking examinations, primary professional roles and a small population of the rural and remote areas were identified.ConclusionBased on interview data from nine WA XROs, the perception is that they have competence adequate for providing an acceptable quality radiographic service.Implications for practiceA continuous XRO course review, and provision of a video conference support channel, an online XRO networking forum and additional XROs and/or radiographers working with XROs undertaking the radiography examinations were perceived as the appropriate strategies to improve the WA XROs’ radiography practice. However, these require financial and/or managerial support from governments.  相似文献   
79.
目的探究分析标准大骨瓣减压联合颞肌切除术在大面积脑梗死患者中的临床治疗效果。方法从2016年12月-2018年11月我院收治的大面积脑梗死患者中抽选46例,采取数字随机分配法分为两组。试验组24例,采取标准大骨瓣减压联合颞肌切除术治疗,对照组22例,采取单纯标准大骨瓣减压术治疗,对比两组患者临床治疗效果。结果试验组中线回复(11.37±2.11)15.09±2.79mm,对照组中线回复(12.24±3.31)16.22±3.11mm,试验组中线回复情况优于对照组,死亡率(33.33%)明显低于对照组(63.64%),P<0.05,差异具有统计学意义。结论在大面积脑梗死患者中采取标准大骨瓣减压联合颞肌切除术治疗能够有效改善脑梗死情况,降低病死率,临床治疗效果显著。  相似文献   
80.
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