全文获取类型
收费全文 | 7162篇 |
免费 | 857篇 |
国内免费 | 129篇 |
学科分类
医药卫生 | 8148篇 |
出版年
2024年 | 22篇 |
2023年 | 135篇 |
2022年 | 284篇 |
2021年 | 424篇 |
2020年 | 405篇 |
2019年 | 462篇 |
2018年 | 411篇 |
2017年 | 406篇 |
2016年 | 404篇 |
2015年 | 353篇 |
2014年 | 510篇 |
2013年 | 523篇 |
2012年 | 409篇 |
2011年 | 411篇 |
2010年 | 314篇 |
2009年 | 297篇 |
2008年 | 300篇 |
2007年 | 273篇 |
2006年 | 251篇 |
2005年 | 194篇 |
2004年 | 156篇 |
2003年 | 159篇 |
2002年 | 124篇 |
2001年 | 91篇 |
2000年 | 78篇 |
1999年 | 72篇 |
1998年 | 59篇 |
1997年 | 51篇 |
1996年 | 64篇 |
1995年 | 66篇 |
1994年 | 57篇 |
1993年 | 40篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 33篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 35篇 |
1984年 | 19篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1981年 | 23篇 |
1980年 | 10篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1975年 | 4篇 |
排序方式: 共有8148条查询结果,搜索用时 15 毫秒
1.
《Journal de gynecologie, obstetrique et biologie de la reproduction》2015,44(5):411-418
2.
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
3.
一阶导数高速脉冲极谱法用于盐酸普鲁卡因的定量分析 总被引:2,自引:0,他引:2
研究了一阶导数高速脉冲极谱法,并运用于盐酸普鲁卡因及其注射制剂的定量分析。在-0.04 V(对 Ag/AgCl)处出现的良好导数峰,于1.0~6.0×10~(-4)mol/L 范围内,导数峰电流与浓度呈线性关系。检测限为3.0×10~(-8)mol/L。操作简便、快速、灵敏,结果准确。 相似文献
4.
We focus on the Fisher information matrix used for design evaluation and optimization in nonlinear mixed effects multiple response models. We evaluate the appropriateness of its expression computed by linearization as proposed for a single response model. Using a pharmacokinetic–pharmacodynamic (PKPD) example, we first compare the computation of the Fisher information matrix with approximation to one derived from the observed matrix on a large simulation using the stochastic approximation expectation–maximization algorithm (SAEM). The expression of the Fisher information matrix for multiple responses is also evaluated by comparison with the empirical information obtained through a replicated simulation study using the first‐order linearization estimation methods implemented in the NONMEM software (first‐order (FO), first‐order conditional estimate (FOCE)) and the SAEM algorithm in the MONOLIX software. The predicted errors given by the approximated information matrix are close to those given by the information matrix obtained without linearization using SAEM and to the empirical ones obtained with FOCE and SAEM. The simulation study also illustrates the accuracy of both FOCE and SAEM estimation algorithms when jointly modelling multiple responses and the major limitations of the FO method. This study highlights the appropriateness of the approximated Fisher information matrix for multiple responses, which is implemented in PFIM 3.0, an extension of the R function PFIM dedicated to design evaluation and optimization. It also emphasizes the use of this computing tool for designing population multiple response studies, as for instance in PKPD studies or in PK studies including the modelling of the PK of a drug and its active metabolite. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
目的探讨初次献血对红细胞膜Na+-K+-ATP酶活性的影响.方法应用比色法分别检测50例符合献血条件的健康初次献血者献血前后的红细胞膜Na+-K+-ATP酶活性,并对结果进行分析.结果初次献血者献血前后红细胞膜Na+-K+-ATP酶活性分别为3.121±0.441和2.907±0.397 μmol.Pi/107 RBC.h,两者比较无明显差异(P>0.05).结论初次献血对红细胞膜Na+-K+-ATP酶活性无影响,献血不会造成红细胞功能损伤. 相似文献
6.
本文报道242例高脂血症患者血小板(PLT)、平均血小板数(MPLT)及平均血小板体积(MPV)等参数的测定结果,其中高胆固醇并高甘油三酯患者,PLT、MPLT及巨大血小板比例(Macro-PLT)高于正常,MPV正常;而单纯高胆固醇或高甘油三酯患者,上述指标与正常人无显著性差异。提示高胆固醇并高甘油三酯患者,存在血小板生成动力学异常,其血小板的破坏增加,生成率加速、但处于一种高水平的动态平衡之中。这可能是高脂血症出现高凝状态的原因之一。同时表明此类患者使用抗血小板疗法具有一定的合理性和必要性。 相似文献
7.
Jason P. Glover DPM Christopher F. Hyer DPM Gregory C. Berlet MD Thomas H. Lee MD 《The Journal of foot and ankle surgery》2008,47(3):237-242
In our retrospective study, we report the objective results of the Mau osteotomy in the treatment of hallux valgus. We reviewed the results of 24 cases of moderate to severe hallux valgus deformities corrected with the Mau osteotomy of the first metatarsal combined with a distal soft-tissue procedure. Follow-up was possible in 24 cases. Preoperatively the mean hallux valgus and first intermetatarsal angles were 31.3 degrees and 16.6 degrees respectively, and were corrected postoperatively to an average of 13.00 degrees+/-7.15 degrees and 9.80 degrees+/-2.43 degrees respectively (P< .001). In the sagittal plane, the first metatarsal was shortened by an average of 2.00 mm. Two (8.3%) cases had dorsal elevation of the osteotomy fragment. Complications included 3 recurrences of the deformity, 1 frank nonunion, 8 dorsal cortical nonunions, 5 cases of undercorrection, and 1 case of broken hardware that was present in the nonunion that went on to revision. There were no superficial or deep infections, and no cases of transfer metatarsalgia were noted. In this series, the use of an oblique first metatarsal osteotomy with a dorsal shelf resulted in reliable and powerful correction of the first intermetatarsal angle in patients with moderate to severe hallux valgus. Particular attention should be paid to severe IM angles and the possibility of undercorrections. Despite ambulation postoperatively, the Mau osteotomy minimized dorsal malunion and the incidence of transfer metatarsalgia. LEVEL OF CLINICAL EVIDENCE: 4. 相似文献
8.
Harwant S. Gill Michael W. O'Boyle Julie Hathaway 《Cortex; a journal devoted to the study of the nervous system and behavior》1998,34(5):707-718
Alpha power (8–12 Hz) was monitored over the frontal, temporal, parietal and occipital lobes of the left and right cerebral hemispheres while participants mentally rotated three-dimensional shapes to match a specified target. By comparing the activational patterns generated during three experimental conditions, each designed to systematically isolate the involvement of the various subcomponents comprising this mental rotation task, it was suggested that the right frontal lobe mediates encoding and comparison/decision processes, while the left parietal and the left temporal region appear most involved in the generation of images and their mental rotation. A preliminary model describing the cooperative interaction of these cortical regions during mental rotation tasks is proposed. 相似文献
9.
Levodopa improves physical fatigue in Parkinson's disease: a double-blind, placebo-controlled, crossover study. 总被引:1,自引:0,他引:1
Jau-Shin Lou Greg Kearns Theodore Benice Barry Oken Gary Sexton John Nutt 《Movement disorders》2003,18(10):1108-1114
We quantitatively investigated the effect of carbidopa/levodopa (25/100) on physical fatigue during finger tapping and force generation in a double-blind, placebo-controlled crossover study. Parkinson's disease (PD) subjects were randomly assigned to carbidopa/levodopa or placebo for Visit 1 or 2 and participated in the following two studies: (1) Finger tapping. Twenty-five PD patients used their index fingers to strike two keys 20 cm apart on a musical instrument digital interface (MIDI) keyboard. The slopes of the regression line of dwell time and movement time were used to assess the rate of fatigue development. (2) Force generation. Twelve PD patients contracted the wrist extensors maximally to obtain a baseline maximum voluntary contraction (BMVC) force. Then they repetitively contracted the wrist extensors at 50% of the BMVC for 7 seconds and rested for 3 seconds. An interval maximum voluntary contraction (IMVC) was measured every three repetitions. Fatigue was defined as an IMVC of less than 60% of the BMVC. The slope of the regression line of IMVC was used to assess the rate of force decline. These two studies were repeated 1 hour after carbidopa/levodopa (25/100) or placebo. Subjects filled out the Multidimensional Fatigue Inventory (MFI) at the beginning of the first visit. Results showed that the slope of dwell time decreased with levodopa but not with placebo (P = 0.004). The rate of force decline also decreased with levodopa but not with placebo (P = 0.01). The subscores in the dimension of physical fatigue in the MFI did not correlate with the rate changes in dwell time or the rate changes in force decline. We concluded that (1) levodopa improves physical fatigue in finger tapping and force generation, (2) physical fatigue in Parkinson's disease is at least partially related to dopamine deficiency, and (3) the MFI measures different aspects of physical fatigue compared with those measured by finger tapping and force generation. 相似文献
10.
M Wall 《Pediatric pulmonology》1989,6(2):71-73
The question of whether functional residual capacity (FRC) falls in infants during active sleep has been clouded by studies using different subject groups and techniques for measurements of lung volume and determination of sleep state. Twenty healthy full-term infants within the first week of life participated in the present study. Neurophysiological and behavioral criteria were used to define sleep state, and measurements of FRC were made using a specially constructed closed-circuit helium dilution system. Regularity of respiration was recorded using magnetometers on the chest and a modified respirator monitor. Results showed that no significant changes in FRC occurred, related either to sleep state or to regularity of respiration. In addition, we failed to detect any differences in FRC between the sexes. Pediatr Pilmonol. 1989; 7:71–77 . 相似文献