全文获取类型
收费全文 | 4794篇 |
免费 | 207篇 |
国内免费 | 69篇 |
专业分类
耳鼻咽喉 | 84篇 |
儿科学 | 29篇 |
妇产科学 | 47篇 |
基础医学 | 334篇 |
口腔科学 | 147篇 |
临床医学 | 304篇 |
内科学 | 375篇 |
皮肤病学 | 42篇 |
神经病学 | 260篇 |
特种医学 | 177篇 |
外科学 | 1057篇 |
综合类 | 620篇 |
预防医学 | 334篇 |
眼科学 | 62篇 |
药学 | 455篇 |
7篇 | |
中国医学 | 73篇 |
肿瘤学 | 663篇 |
出版年
2024年 | 11篇 |
2023年 | 68篇 |
2022年 | 116篇 |
2021年 | 163篇 |
2020年 | 134篇 |
2019年 | 135篇 |
2018年 | 138篇 |
2017年 | 127篇 |
2016年 | 118篇 |
2015年 | 132篇 |
2014年 | 325篇 |
2013年 | 314篇 |
2012年 | 255篇 |
2011年 | 320篇 |
2010年 | 287篇 |
2009年 | 285篇 |
2008年 | 255篇 |
2007年 | 262篇 |
2006年 | 205篇 |
2005年 | 177篇 |
2004年 | 143篇 |
2003年 | 121篇 |
2002年 | 103篇 |
2001年 | 100篇 |
2000年 | 72篇 |
1999年 | 71篇 |
1998年 | 64篇 |
1997年 | 61篇 |
1996年 | 54篇 |
1995年 | 35篇 |
1994年 | 43篇 |
1993年 | 33篇 |
1992年 | 32篇 |
1991年 | 26篇 |
1990年 | 25篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 26篇 |
1986年 | 24篇 |
1985年 | 32篇 |
1984年 | 27篇 |
1983年 | 10篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1974年 | 7篇 |
1973年 | 6篇 |
排序方式: 共有5070条查询结果,搜索用时 15 毫秒
51.
Summary Four groups of subjects of different ages and sex (group I: 20–29 years, women; group II: 20–29 years, men; group III: 30–39 years, women; group IV: 30–39 years, men) undertook dynamic one-hand work (load range 40%–80% of maximum voluntary contraction, at 60 working cycles/min) to allow a study of cardiovascular responses as shown by the resultant changes in blood pressure and heart rate. During fatiguing dynamic one-hand work, there was a large increase in systolic and diastolic blood pressures in both sexes after a few minutes. For all load levels, the systolic blood pressure was found to be higher by about 4 kPa in men (groups II and IV) than in women (groups I and III). Other age-related differences became evident in the diastolic blood pressure changes. The values obtained for the older groups were higher than those in the two younger groups. These differences in blood pressure response are possibly due to sex-related differences in the release of catecholamines, or to age-related organic changes in the vessels. 相似文献
52.
Yutaka Endo Jun -Ichi Nishimura Fukuko Kimura 《Pflügers Archiv : European journal of physiology》1994,426(3-4):183-188
The present study examined the effect of glucocorticoid manipulations on local cerebral blood flow in the hippocampus. We measured local cerebral blood flow in the hippocampus at 1-h intervals over a 1-day period in freely moving rats, by means of the H2 clearance method, before and after sham adrenalectomy, adrenalectomy or adrenalectomy with corticosterone replacement. We also measured local cerebral blood flow in the prefrontal cortex before and after adrenalectomy. Four weeks after the adrenalectomy, hippocampal blood flow at each time of day was an average of 47% greater than before the operation, showing diurnal variation as before. After the sham adrenalectomy or adrenalectomy with corticosterone replacement, hippocampal blood flow did not change significantly with respect to either its level or its diurnal variation. Local cerebral blood flow in the prefrontal cortex increased by only 19% after adrenalectomy. The present study demonstrates that adrenalectomy causes a remarkable increase in hippocampal blood flow, probably due to a lack of corticosterone. 相似文献
53.
F. Lasbennes J. Seylaz 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1986,63(1):169-172
Summary The cerebrovascular consequences of the gentle restraint commonly used for the measurement of local cerebral blood flow (LCBF) in conscious rats has been tested by using two drugs, propranolol and diazepam. Propranolol induced small LCBF decreases in 7 structures suggesting that the cerebral circulation was partially controlled by the activation of intra or extracerebral aminergic pathways in this protocol. Sedative doses of diazepam reduced LCBF in most of the structures but anxiolytic doses increased it in 4 structures. This effect may be due to a regionally differentiated modification of activity in the brain due to the selective inhibition of limbic structures by diazepam. Since propranolol and diazepam induced only small changes, the LCBF of gently restrained rats appeared to be minimally affected by the stressful situation imposed by the protocol. 相似文献
54.
Separate detectors for simple and complex grating patterns? 总被引:1,自引:0,他引:1
Grating having two sinusoidal components show a periodic variation in contrast which is visible as a "beat" pattern. The spatial frequency of the beat is the difference between the frequencies of the two components. Thresholds for a number of detection and discrimination tasks were measured using beat patterns of 1 c/deg (with components of 9 and 10 c/deg), and gratings of 1 and 10 c/deg. Temporal modulation at 6 Hz lowered detection thresholds for 1 c/deg gratings, but not for beats or 10 c/deg gratings. The effect of contrast on the range of temporal frequencies over which direction of movement can be discriminated differs for the three types of pattern: beats resemble neither low nor high spatial frequency gratings. Low and (for 2 of 3 observers) high spatial frequency gratings, but not beat patterns, are susceptible to a movement after effect induced by a low spatial-frequency grating. Beat patterns induce little or no movement after effect. We conclude that beat patterns are not detected by the same mechanisms that detect simple gratings. 相似文献
55.
Negative afterimages were observed after steady fixation of sinusoidal gratings at low spatial frequencies, and quantified using contrast-matching and cancellation methods. Afterimage contrast increased as a power function of "exposure", defined as the product of inspection contrast and inspection duration. A single function, linear on a log-log plot, describes the afterimages of gratings at different spatial frequencies, contrasts and durations. The matching method yielded a lower slope (about 0.42) than the cancellation method (0.62), probably because contrast adaptation attenuates perceived afterimage contrast in the first method, but not the second. Square-wave gratings, and those containing two or three harmonic components gave much weaker afterimages (assessed by contrast-matching) than sine-waves did. Contrast adaptation may again be responsible. Hemi-field asymmetries in contrast perception were noted. The contrast of real gratings and afterimages was nearly additive, especially at lower exposures, but the results cannot distinguish between linear filter and gain control models of "local adaptation". 相似文献
56.
吾超杜艳玲李爽张琳苑李沛贺世喆郎红娟 《中国卫生质量管理》2021,(8):047-50
目的构建高校护理学教师教学能力评价指标体系。 方法通过文献回顾、质性访谈、专家会议等方法,基于CIPP初步构建指标条目池,采用德尔菲法进行两轮咨询确定最终指标体系。 采用Epidata 3.0 录入数据,使用SPSS 23.0软件进行数据分析。结果两轮咨询问卷有效回收率分别为90%、100%,提出建议专家比率分别为83.33%、16.67%;两轮咨询专家权威系数均为0.892;一级、二级指标第一轮咨询协调系数分别为0.216、0.215,第二轮协调系数分别为0.262、0.279。高校护理学教师教学能力评价指标体系包含4个一级指标和30个二级指标。结论基于CIPP评价模式构建的高校护理学教师教学能力评价指标体系科学性较强,有利于综合评价高校护理学教师教学能力,促进教师提升教学能力。 相似文献
57.
目的 观察动脉内接触性溶栓治疗急性脑梗死的临床疗效 ,评价其在神经功能障碍恢复和脑血管再通疗效。方法 选择急性脑梗死发病均在 6h以内 ,采用动脉内接触性溶栓进行治疗 ,溶栓药为尿激酶。结果 共有 9例患者入选 ,有 3例闭塞血管完全再通 ,5例部分再通 ,1例无再通 ,溶栓后患者神经功能缺损明显改善 ,治疗前后患者欧洲脑卒中评分有明显差异 (P <0 0 5) ,溶栓前后患者纤维蛋白原、凝血时间有明显差异 (P <0 0 5) ,1例出现消化道出血 ,1例伴有皮下出血 ,1例发生再灌注损伤。结论 动脉内接触性溶栓治疗急性脑梗死可以提高闭塞血管的再通率 ,明显促进神经功能障碍的恢复 ,改善血液高凝状态 ,副作用少 ,疗效确切 相似文献
58.
59.
Ignacio Aguirre-Allende Jose Maria Enriquez-Navascues Garazi Elorza-Echaniz Ane Etxart-Lopetegui Nerea Borda-Arrizabalaga Yolanda Saralegui Ansorena Carlos Placer-Galan 《Cirugía espa?ola》2021,99(2):89-107
Local excision (LE) has arisen as an alternative to total mesorectal excision for the treatment of early rectal cancer. Despite a decreased morbidity, there are still concerns about LE outcomes.This systematic-review and meta-analysis design is based on the “PICO” process, aiming to answer to three questions related to LE as primary treatment for early-rectal cancer, the optimal method for LE, and the potential role for completion treatment in high-risk histology tumors and outcomes of salvage surgery.The results revealed that reported overall survival (OS) and disease-specific survival (DSS) were 71%–91.7% and 80%–94% for LE, in contrast to 92.3%–94.3% and 94.4%–97% for radical surgery. Additional analysis of National Database studies revealed lower OS with LE (HR: 1.26; 95%CI, 1.09–1.45) and DSS (HR: 1.19; 95%CI, 1.01–1.41) after LE. Furthermore, patients receiving LE were significantly more prone develop local recurrence (RR: 3.44, 95%CI, 2.50–4.74). Analysis of available transanal surgical platforms was performed, finding no significant differences among them but reduced local recurrence compared to traditional transanal LE (OR:0.24;95%CI, 0.15–0.4). Finally, we found poor survival outcomes for patients undergoing salvage surgery, favoring completion treatment (chemoradiotherapy or surgery) when high-risk histology is present.In conclusion, LE could be considered adequate provided a full-thickness specimen can be achieved that the patient is informed about risk for potential requirement of completion treatment. Early-rectal cancer cases should be discussed in a multidisciplinary team, and patient's preferences must be considered in the decision-making process. 相似文献
60.
保留下颌骨舌癌联合根治术后复发部位及其因素的分析 总被引:4,自引:0,他引:4
作者报道68例行保留下颌骨舌癌联合根治术病例,其中术后复发23例,复发率为33.8%。在这23例中,其复发部位为:局部复发15例,对侧颈淋巴结转移7例,肝转移1例。这表明术后局部复发病例数最多,占65.2%(15/23)。此类复发病例再无拯救手术机会、预后极差。本文还着重分析了术后复发因素。认为术后复发与肿瘤原发部位及原发灶病变范围有关。 相似文献