全文获取类型
收费全文 | 309827篇 |
免费 | 18470篇 |
国内免费 | 8629篇 |
专业分类
耳鼻咽喉 | 3331篇 |
儿科学 | 9377篇 |
妇产科学 | 3693篇 |
基础医学 | 25853篇 |
口腔科学 | 6216篇 |
临床医学 | 35960篇 |
内科学 | 49557篇 |
皮肤病学 | 3510篇 |
神经病学 | 20575篇 |
特种医学 | 15650篇 |
外国民族医学 | 27篇 |
外科学 | 40502篇 |
综合类 | 34698篇 |
现状与发展 | 31篇 |
一般理论 | 5篇 |
预防医学 | 27982篇 |
眼科学 | 5337篇 |
药学 | 32801篇 |
222篇 | |
中国医学 | 7471篇 |
肿瘤学 | 14128篇 |
出版年
2024年 | 688篇 |
2023年 | 3829篇 |
2022年 | 10805篇 |
2021年 | 13657篇 |
2020年 | 8638篇 |
2019年 | 13585篇 |
2018年 | 8212篇 |
2017年 | 7408篇 |
2016年 | 9658篇 |
2015年 | 12627篇 |
2014年 | 23658篇 |
2013年 | 21566篇 |
2012年 | 24185篇 |
2011年 | 21319篇 |
2010年 | 18895篇 |
2009年 | 18145篇 |
2008年 | 16823篇 |
2007年 | 16606篇 |
2006年 | 14273篇 |
2005年 | 10079篇 |
2004年 | 6093篇 |
2003年 | 5270篇 |
2002年 | 4186篇 |
2001年 | 3498篇 |
2000年 | 3008篇 |
1999年 | 2168篇 |
1998年 | 2577篇 |
1997年 | 2392篇 |
1996年 | 1973篇 |
1995年 | 1979篇 |
1994年 | 1895篇 |
1993年 | 1509篇 |
1992年 | 1707篇 |
1991年 | 1548篇 |
1990年 | 1497篇 |
1989年 | 1428篇 |
1988年 | 1367篇 |
1987年 | 1222篇 |
1986年 | 1044篇 |
1985年 | 2081篇 |
1984年 | 2153篇 |
1983年 | 1516篇 |
1982年 | 1629篇 |
1981年 | 1582篇 |
1980年 | 1374篇 |
1979年 | 1144篇 |
1978年 | 909篇 |
1977年 | 890篇 |
1976年 | 764篇 |
1974年 | 509篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
目的:探讨妊娠早期血清学指标糖化血红蛋白(glycohemoglobin,HbA1c)联合妊娠相关血浆蛋白A(pregnancy-associated plasma protein A,PAPP-A)对妊娠期糖尿病(gestational diabetes mellitus,GDM)的预测意义。方法:随机选取2018年12月1日-2019年7月30日孕11~13+6周于我院门诊产检的妊娠妇女,进行临床资料采集并记录妊娠早期(11~13+6周)空腹血糖(fasting plasma glucose,FPG)、HbA1c、PAPP-A中位数倍数(multiple of the median,MoM)水平,根据孕24~28周进行的75 g口服葡萄糖耐量试验(oral glucose tolerance test,OGTT)结果将研究对象分为研究组和对照组,统计分析妊娠早期血清学指标预测GDM的最佳截断值并得出最适宜的联合预测方案。结果:多因素Logistic回归分析显示,高水平FPG和HbA1c、低水平PAPP-A、受孕方式采用辅助生殖技术、有家族糖尿病史以及妊娠早期体质量指数(BMI)为超重或肥胖均是GDM发生的独立危险因素。有糖尿病家族史和使用辅助生殖技术受孕发生GDM的风险显著增高(OR分别为7.206和47.512,均P<0.001)。分析不同预测指标的受试者工作特征(receiver operating characteristic,ROC)曲线及曲线下面积(area under the curve,AUC)显示,PAPP-A MoM联合HbA1c及FPG诊断时AUC最大(0.728),其后依次为PAPPA MoM联合HbA1c(0.721)、HbA1c联合FPG(0.717),均大于HbA1c(0.707)和FPG(0.647),而PAPP-A MoM的AUC为0.380,对GDM没有诊断意义。结论:具有高风险因素的孕妇,推荐在妊娠早期联合检测HbA1c与PAPPA MoM,以早期预测GDM。 相似文献
152.
153.
IntroductionDural puncture epidural (DPE) analgesia is a modification of conventional epidural analgesia that involves the intentional puncture of the dura with a spinal needle through the needle placed in the epidural space, without a medication being injected intrathecally. There have been contradictory findings regarding better analgesia and better block quality.MethodsA systematic literature search was done to identify randomized controlled trials (RCT) comparing DPE with epidural analgesia. The risk of bias was assessed with the Cochrane tool. Risk ratio and 95% confidence intervals were calculated.ResultsFive RCTs including 581 patients were identified. One RCT on caesarean section was excluded. Single studies suggested slightly better analgesia by finding a median time to achieve sufficient analgesia of two minutes less in the DPE group, a higher number of women having a pain score <10/100 at 20 min, a reduction in the number of epidural top-ups and better sacral spread. The studies did not show a difference between DPE and epidural analgesia for catheter replacement or manipulation rates, the incidence of intravascular placement or unilateral block.ConclusionThere is a lack of clear evidence on either the benefits or the risks of the DPE technique, such that a recommendation for or against its routine use is premature. Two of the three studies showing a beneficial effect of DPE came from the same institution and replication of the findings by other groups is warranted. 相似文献
154.
A. Ríos A.I. López-Navas M.A. Ayala G. Garrido M.J. Sebastián J. Carrillo Á. Sánchez J. Flores-Medina J.J. Ruiz-Manzanera A.M. Hernández P. Ramírez P. Parrilla 《Transplantation proceedings》2019,51(2):258-260
The Latin American population has a double way of immigration, one toward the United States by proximity and another toward Spain by sociocultural affinity. This population increase is affecting organ donation and transplantation in receiving countries.
Objective
To analyze the brain death (BD) concept knowledge in the Dominican Republic immigrant population in Florida (United States) and Spain.Method
Population under study: Population born in the Dominican Republic, resident in Florida (United States) and in Spain. Inclusion criteria: Population older than 15 years stratified by age and sex. Assessment instrument: Donation attitude questionnaire PCID-DTO-Ríos. Fieldwork: Random selection based on stratification. Immigration support association collaboration in Florida and Spain was needed to locate potential respondents. Completion was anonymous and self-administered, with verbal consent.Results
A total of 123 respondents, 57 residents in Spain and 66 in Florida, have been included in the study. The 27% (n = 33) of the respondents knowledgeable of the BD concept consider it the death of an individual. Of the remainder, 52% (n = 64) do not know about it, and the remaining 21% (n = 26) believe it does not mean the death of a patient. No differences were observed regarding migration countries (P > .05). There was no association of the BD concept with other psychosocial factors analyzed or with the attitude toward organ donation.Conclusions
Knowledge of the BD concept among the Dominican immigrant population is similar in Spain and Florida, and, unlike most studies, there is no objective association with the attitude toward organ donation. 相似文献155.
156.
157.
Solid-state reactions between sodium hydride and sodium hydroxide are unusual among hydride-hydroxide systems since hydrogen can be stored reversibly. In order to understand the relationship between hydrogen uptake/release properties and phase/structure evolution, the dehydrogenation and hydrogenation behavior of the Na-O-H system has been investigated in detail both ex- and in-situ. Simultaneous thermogravimetric-differential thermal analysis coupled to mass spectrometry (TG-DTA-MS) experiments of NaH-NaOH composites reveal two principal features: Firstly, an H2 desorption event occurring between 240 and 380 °C and secondly an additional endothermic process at around 170 °C with no associated weight change. In-situ high-resolution synchrotron powder X-ray diffraction showed that NaOH appears to form a solid solution with NaH yielding a new cubic complex hydride phase below 200 °C. The Na-H-OH phase persists up to the maximum temperature of the in-situ diffraction experiment shortly before dehydrogenation occurs. The present work suggests that not only is the inter-phase synergic interaction of protic hydrogen (in NaOH) and hydridic hydrogen (in NaH) important in the dehydrogenation mechanism, but that also an intra-phase Hδ+… Hδ– interaction may be a crucial step in the desorption process. 相似文献
158.
159.
Shinji Naganawa Rintaro Ito Hisashi Kawai Toshiaki Taoka Tadao Yoshida Michihiko Sone 《Magnetic resonance in medical sciences》2020,19(4):375
Purpose:It has been reported previously that intravenously administered gadolinium-based contrast agent (GBCA) leaks into the subarachnoid space around the cortical veins at 4 h after injection in all old people over 37 years, but not in younger people up to 37 years of age in 3D-real IR images. The purpose of this study was to investigate whether there was a strict threshold of 37 years of age for the leakage of the GBCA into the subarachnoid space.Methods:The subjects included 190 patients, that were scanned for 3D-real IR images at 4 hours after intravenous injection of GBCA as a diagnostic test for endolymphatic hydrops. The patient’s age ranged from 14 to 81 years. Two experienced neuroradiologists evaluated the images to determine whether the GBCA leakage around the cortical veins was positive or negative. Any discrepancies between the two observers were discussed and a consensus was obtained.A Mann–Whitney U test and receiver operating characteristic (ROC) curve analysis were used to compare the positive and the negative group and to set the age cut-off value for the prediction of GBCA leakage.Results:The GBCA leakage around the cortical veins was negative in 35 patients and positive in 155 patients. The average age was 33 ± 11 years in the negative group, and 55 ± 12 years in the positive group (P < 0.01). In the ROC analysis for the age and leakage of the GBCA, an area under the curve was 0.905 and the cut-off age was 37.317 years (sensitivity of 0.942 and specificity of 0.771).Conclusion:Intravenously administered GBCA leaks into the subarachnoid space around the cortical veins in most patients over 37 years of age. However, it should be noted that it can be found occasionally in patients under 37 years of age. 相似文献