全文获取类型
收费全文 | 71492篇 |
免费 | 7668篇 |
国内免费 | 5152篇 |
专业分类
耳鼻咽喉 | 601篇 |
儿科学 | 691篇 |
妇产科学 | 745篇 |
基础医学 | 8090篇 |
口腔科学 | 1318篇 |
临床医学 | 9843篇 |
内科学 | 10738篇 |
皮肤病学 | 752篇 |
神经病学 | 3796篇 |
特种医学 | 2474篇 |
外国民族医学 | 60篇 |
外科学 | 7061篇 |
综合类 | 12960篇 |
现状与发展 | 27篇 |
一般理论 | 6篇 |
预防医学 | 5047篇 |
眼科学 | 2014篇 |
药学 | 8029篇 |
69篇 | |
中国医学 | 4122篇 |
肿瘤学 | 5869篇 |
出版年
2024年 | 343篇 |
2023年 | 1357篇 |
2022年 | 3293篇 |
2021年 | 4061篇 |
2020年 | 3190篇 |
2019年 | 2567篇 |
2018年 | 2597篇 |
2017年 | 2503篇 |
2016年 | 2235篇 |
2015年 | 3435篇 |
2014年 | 4299篇 |
2013年 | 3703篇 |
2012年 | 5512篇 |
2011年 | 5883篇 |
2010年 | 3561篇 |
2009年 | 2775篇 |
2008年 | 3751篇 |
2007年 | 3586篇 |
2006年 | 3524篇 |
2005年 | 3375篇 |
2004年 | 2216篇 |
2003年 | 2151篇 |
2002年 | 1804篇 |
2001年 | 1513篇 |
2000年 | 1530篇 |
1999年 | 1758篇 |
1998年 | 1070篇 |
1997年 | 1033篇 |
1996年 | 754篇 |
1995年 | 675篇 |
1994年 | 674篇 |
1993年 | 411篇 |
1992年 | 574篇 |
1991年 | 439篇 |
1990年 | 396篇 |
1989年 | 333篇 |
1988年 | 318篇 |
1987年 | 261篇 |
1986年 | 219篇 |
1985年 | 181篇 |
1984年 | 98篇 |
1983年 | 60篇 |
1982年 | 46篇 |
1981年 | 41篇 |
1980年 | 19篇 |
1979年 | 42篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1964年 | 7篇 |
1936年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
儿童哮喘的发病率逐年上升.基于卫生假说,抗生素使用可能减少了微生物暴露,从而增加了过敏性疾病发生的风险.近十年来,就早期抗生素暴露与儿童哮喘的关系进行的大量的流行病学调查的结果并不一致.大多数回顾性研究发现正相关联系,但前瞻性研究未发现联系或联系强度较弱.逆向因果和指示混淆可部分解释两者的关系,但也难以否定因果关系的存在. 相似文献
2.
3.
4.
5.
6.
X Dong M He X Song B Lu Y Yang S Zhang N Zhao L Zhou Y Li X Zhu R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks. 相似文献
7.
8年间剖宫产率及指证变化的临床分析 总被引:3,自引:1,他引:2
近年来,我国各地的剖宫产率均呈明显的上升趋势,部分地区的剖宫产率甚至高达60%。居高不下的剖宫产率已引起了广大产科工作者和全社会的广泛关注。对我院近8年来剖宫产病例的临床资料进行回顾性分析,以寻求剖宫产率逐年上升的原因及探讨降低剖宫产率的途径与方法。 相似文献
8.
After a comprehensive rernew of the literature on syphilitic
aortitis, Longcope, (1) stated in 1913; ": . . . the presence of spiro:
chetes in these lesions, as might be expected, cannot by any means be
constantly demonstrated with Levaaiti stain. . . . . . . That these
organisms are ''Treponema pallidum seems almost certain thouS:h actual
proof of such by culture from the arterial lesions, a most difficult task,
or direct inoculation into animals, has not as yet been accomplished." 相似文献
9.
多囊卵巢综合征患者卵巢间质胰岛素样生长因子受体的表达 总被引:3,自引:0,他引:3
目的:探讨肥胖及非肥胖多囊卵巢综合征(PCOS)患者卵巢间质胰岛素样生长因子(IGF-Ⅰ)受体基因的定量表达。方法:用逆转录基因扩增技术(RT-PCR),检测35例PCOS患者(肥胖组15例,非肥胖组20例)及20例正常妇女(对照组)卵巢间质细胞IGF-Ⅰ受体mRNA的表达量(灰度比值)。并对IGF-Ⅰ受体基因mRNA逆转录的cDNA产物进行限制性内切酶酶切分析。结果:PCOS两组IGF-Ⅰ受体基因的表达量显著高于对照组,PCOS两组灰度比值为1.184±0.240,对照组灰度比值为0.999±0.086(P<0.001)。非肥胖组(1.238±0.387)明显大于肥胖组(1.058±0.109,P<0.1)。酶切分析证实,3组IGF-Ⅰ受体基因扩增片段相同,PCOS两组未发现明显的碱基突变存在。结论:PCOS患者卵巢间质IGF-Ⅰ受体基因呈过度表达。且PCOS非肥胖患者局部IGF-I受体表达高于PCOS肥胖患者。 相似文献
10.
This study determined the accuracy of fit of three-unit fixed partial dentures joined by an infrared soldering technique compared with one-piece fixed partial denture castings and individually cast crowns. Wax patterns of prepared Ivorine teeth, maxillary left central incisor and maxillary left canine, were injection molded; a plastic rod was used as a pontic. One group of patterns was cast as one-piece dentures; the other group was sectioned in the connector area, cast individually and then joined by infrared soldering. Castings were seated on their respective dies, embedded in epoxy resin, and sectioned. Gap distances between the casting and the die were measured at specified marginal sites with a profile projector. Results showed that the fit of infrared-soldered fixed partial dentures was significantly better than that of one-piece castings and was comparable with the fit of single crowns. The gap openings measured in all castings were within the range of clinical acceptability. 相似文献