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   14431篇
  免费   825篇
  国内免费   212篇
耳鼻咽喉   62篇
儿科学   125篇
妇产科学   61篇
基础医学   1601篇
口腔科学   267篇
临床医学   1173篇
内科学   2078篇
皮肤病学   250篇
神经病学   3012篇
特种医学   465篇
外国民族医学   1篇
外科学   1208篇
综合类   1282篇
预防医学   1801篇
眼科学   271篇
药学   1130篇
  5篇
中国医学   449篇
肿瘤学   227篇
  2024年   43篇
  2023年   332篇
  2022年   492篇
  2021年   705篇
  2020年   634篇
  2019年   701篇
  2018年   594篇
  2017年   386篇
  2016年   381篇
  2015年   369篇
  2014年   872篇
  2013年   745篇
  2012年   711篇
  2011年   800篇
  2010年   662篇
  2009年   633篇
  2008年   621篇
  2007年   623篇
  2006年   505篇
  2005年   402篇
  2004年   354篇
  2003年   330篇
  2002年   279篇
  2001年   233篇
  2000年   216篇
  1999年   190篇
  1998年   190篇
  1997年   167篇
  1996年   166篇
  1995年   144篇
  1994年   138篇
  1993年   141篇
  1992年   135篇
  1991年   132篇
  1990年   133篇
  1989年   105篇
  1988年   105篇
  1987年   110篇
  1986年   124篇
  1985年   193篇
  1984年   142篇
  1983年   106篇
  1982年   89篇
  1981年   84篇
  1980年   68篇
  1979年   55篇
  1978年   24篇
  1977年   41篇
  1976年   21篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Summary Intraoperative mapping techniques allow a reliable identification or exclusion of eloquent brain areas and are well tolerated by the patients. In dominant opercular tumours radical surgery can only be achieved without lasting deficits with intraoperative histological examination of the resection line and mapping. If an early post-operative MRI shows residual opercular tumour in non-eloquent areas re-operation is recommended.In large dominant insular or opercular-insular tumours only biopsy is recommended, because only an incomplete removal can be accomplished, because the trial of radical removal carries a high risk of postoperative deficits due to possible vascular damage of the lenticulo-striate arteries or internal capsule. Because subtotal removal of low grade gliomas does not increase the progression free interval, we would not recommend surgery in these cases, as they carry a significant risk of a further deficit.  相似文献   
42.
An examination was made of neurogenesis in the anteroventral periventricular nucleus (AVPv) of the preoptic area of the rat using bromodeoxyuridine (BrdU), a thymidine analog, and a BrdU-specific antibody. Cells in the AVPv of adult rats were labeled with the antibody when BrdU was injected into pregnant rats once during day 13 to 18 of gestation, but not during day 10 to 12 nor 19 to 20 of gestation nor on postnatal day 1, indicating that neurogenesis of the AVPv occurs during a limited period from day 13 to 18 of gestation. Next, to examine the effects of androgen on neurogenesis, BrdU was injected once on day 15 into pregnant rats that also received injections of testosterone propionate (TP). The number of BrdU-labeled cells in the AVPv was similar in control female and male fetuses and female fetuses from pregnant rats that received daily injections of TP during days 14 to 16, when fetuses were examined on day 17 of gestation. These results suggest that the neurogenesis that was recognized by labeling with BrdU was not affected by the treatment with TP. On day 21 of gestation, BrdU-labeled cells in the AVPv of control male fetuses and female fetuses that received TP during days 14 to 18 were fewer in number than those in female fetuses of the control group, whereas treatments with TP during days 14 to 16 and during days 17 to 18 did not cause any significant decrease in number of BrdU-labeled cells. These findings support the hypothesis that elimination of a population of cells, for example, by cell death as described previously, is enhanced in male fetuses and in female fetuses treated with TP repetitively.  相似文献   
43.
调查了中国≥50岁中老年农村人群20岁以后的骨折发生情况。共计8266人,骨折率为6.42%;其中男性3771人,骨折率为7.48%;女性4495人,骨折率为5.54%。男性显著高于女性(P<0.01)。同时分析了不同部位的骨折发生情况,其中髋部骨折率为0.68%。骨折与跌跤发生因素密切相关,为此本研究还阐述了最近一年中人群跌倒情况,其跌倒率为11.13%。其结果为人群骨折的预防提供了科学依据。  相似文献   
44.
Movement-related potentials were recorded preceding self-paced voluntary movements in patients with Parkinson's disease and in healthy subjects of the same age group. We compared the Readiness Potential preceding joystick movements in a fixed direction and preceding joystick movements in freely selected directions. In normal subjects the Readiness Potential amplitude was higher preceding freely selected movements than preceding movements in a fixed direction. The Readiness Potential in Parkinson patients failed to be modified by the different modes of movement selection. The modulation of the Readiness Potential by different ways of preparing for movement might be due to the supplementary motor area (SMA) being more strongly engaged by tasks requiring internal control of movements than by tasks that are externally structured. The results suggest that this task-dependent variation of SMA activity is reduced in Parkinson's disease. A failing capacity to adapt SMA activity to different task demands has previously been suggested by evidence from positron emission tomography studies using similar tasks.  相似文献   
45.
Background: Ventral abdominal wall hernias are a common cause of morbidity and mortality. Opinion varies as to appropriate management. A recent consensus meeting on incisional hernia identified the need to standardise repair. On this background, a survey of current practice was performed. Method: A questionnaire was sent to 101 practicing general surgeons within the West of Scotland. Incisional, epigastric and para-umbilical defects were subdivided into defect size <2, 2–5 and >5 cm. The surgeons were asked to indicate the most appropriate repair (suture, mayo or mesh) for each. The influence of reducibility on the decision to repair was also assessed. Results: Sixty-one of 101 questionnaires were returned valid giving a response rate of 60%. Suture repair was significantly more likely to be used in all defects <2 cm (P<0.001). Mesh repair was significantly more likely to be recommended in all defects >5 cm (P<0.001). Of defects >5-cm, mesh was recommended for 90% of incisional hernia compared with 81% of epigastric and 76% of para-umbilical hernia (P<0.001). There was no significant difference in choice of repair for defect size 2–5 cm with opinion divided between suture and mesh. Irreducibility increased the likelihood of recommendation for repair. Conclusion: This survey shows a lack of consensus on the appropriate repair of ventral abdominal wall hernia amonge practicing consultant general surgeons. This reflects the contrasting views within the current literature.  相似文献   
46.
Summary Thirty-three cat brains with injections of horseradish peroxidase in various regions of the cerebral cortex were screened for afferent projections from the ventral tegmental area, the locus ceruleus, and the parabrachial nuclei. All three structures were found to project to rather divergent parts of the cortex, including regions in the posterior half of the hemisphere. These results, especially for the ventral tegmental area and, to a lesser degree, for the parabrachial neurons, disagree with most of the target loci of established cortical afferents in the rat. Though our results might be attributed to species differences in the cortical innervation of brain stem structures, we prefer explanations which emphasize different densities in the distribution of brain stem afferents to the cortex, and/or which suggest different cortical targets of catecholaminergic and noncatecholaminergic neurons.Supported in part by grant Ma 795 from the Deutsche Forschungsgemeinschaft (DFG)  相似文献   
47.
目的介绍一种简单实用而较精确的测量狭窄气管截面积的方法.方法利用纤维支气管镜、测长器、模拟气管等制作并校正测量标尺,并利用该标尺测量了3例气管状况异常患者的气管某一截面面积.结果用校正过的4种测量标尺测量了10个模拟气管的直径,和实测真值比较经t检验分析无显著性差异,利用上述标尺测量的3个患者的目的截面面积分别为约96 mm2、 105 mm2和192 mm2.结论本方法提供了一种简单、快速而又较精确的测量大气道某一截面面积的方法,为定量评价患者的通气功能、选择气管支架或采用其他干预手段处理气管病变提供了数据参考.  相似文献   
48.
49.
目的探讨体表面积(BS)、体质量、体质量指数(BMI)对老年人骨密度(BMD)的影响。方法用双能X线骨密度仪测定1794例老年人腰椎、髋关节的BMD值,并对其与BS等指标进行相关回归分析。结果BS大的老年人其BMD大于BS小者,有显著性差异。在各种指标与BMD的相关性比较中,BS与BMD的相关性最好,其后依次为:体质量、身高、OSTA得分(亚洲人自我骨质疏松筛查工具)、BMI。结论BS比BMI等指标更能反映出人体体型对老年人BMD的影响。  相似文献   
50.
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