全文获取类型
收费全文 | 178592篇 |
免费 | 16305篇 |
国内免费 | 10373篇 |
专业分类
耳鼻咽喉 | 1591篇 |
儿科学 | 2824篇 |
妇产科学 | 1487篇 |
基础医学 | 17149篇 |
口腔科学 | 2974篇 |
临床医学 | 22762篇 |
内科学 | 22648篇 |
皮肤病学 | 2363篇 |
神经病学 | 7408篇 |
特种医学 | 6689篇 |
外国民族医学 | 53篇 |
外科学 | 15820篇 |
综合类 | 37050篇 |
现状与发展 | 39篇 |
一般理论 | 18篇 |
预防医学 | 17004篇 |
眼科学 | 4022篇 |
药学 | 19525篇 |
192篇 | |
中国医学 | 11978篇 |
肿瘤学 | 11674篇 |
出版年
2024年 | 536篇 |
2023年 | 2020篇 |
2022年 | 5148篇 |
2021年 | 6859篇 |
2020年 | 5500篇 |
2019年 | 4479篇 |
2018年 | 4539篇 |
2017年 | 5033篇 |
2016年 | 4862篇 |
2015年 | 7477篇 |
2014年 | 9809篇 |
2013年 | 10601篇 |
2012年 | 15074篇 |
2011年 | 16100篇 |
2010年 | 12700篇 |
2009年 | 10811篇 |
2008年 | 12150篇 |
2007年 | 11990篇 |
2006年 | 11068篇 |
2005年 | 9681篇 |
2004年 | 7346篇 |
2003年 | 7291篇 |
2002年 | 5890篇 |
2001年 | 4619篇 |
2000年 | 3470篇 |
1999年 | 2276篇 |
1998年 | 1211篇 |
1997年 | 1299篇 |
1996年 | 874篇 |
1995年 | 736篇 |
1994年 | 615篇 |
1993年 | 426篇 |
1992年 | 443篇 |
1991年 | 373篇 |
1990年 | 334篇 |
1989年 | 288篇 |
1988年 | 220篇 |
1987年 | 204篇 |
1986年 | 154篇 |
1985年 | 154篇 |
1984年 | 88篇 |
1983年 | 74篇 |
1982年 | 50篇 |
1981年 | 41篇 |
1980年 | 27篇 |
1979年 | 55篇 |
1978年 | 44篇 |
1976年 | 28篇 |
1973年 | 30篇 |
1970年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
在制备了两个Cell Ⅰ-Hep Ⅱ 双结构域重组FN多肽(CH50和CH56)的基础上,研究其抑制肿瘤细胞浸润能力的作用。两个多肽的结构差异是CH50中删除了Cell I和HepⅡ之间的Ⅲ-11和ED-A结构顺序。CH50(ED_(50)为30.2 nmol/L)结合细胞的能力略高于CH56(ED_(50)为45.4 nmol/L)。两种多肽均可显著抑制黑色素瘤B16/F1细胞结合层粘素的能力,抑制作用相同。在体内肿瘤浸润抑制试验中,两种多肽均可显著抑制癌细胞浸润能力,使肺转移结节数降低80%左右。结果提示:Ⅲ-11和ED-A结构顺序对Cell Ⅰ-Hep Ⅱ 双结构域多肽结合细胞的能力有一定的影响,但删除Ⅲ-11和ED-A不是重组多肽抑制肿瘤转移的决定因素,Cell I和Hep Ⅱ 这两个结构域单独连接在一起是其抑制肿瘤细胞转移的结构基础。 相似文献
82.
缺血再灌流肾组织内皮素—1动态变化的实验研究 总被引:7,自引:1,他引:6
在大鼠肾缺血60分钟再灌注的模型上观察不同时相肾静脉血、肾皮质、外髓和内髓的内皮素1(ET1)浓度变化,肾组织ET1光镜和电镜免疫组织化学变化。结果发现:缺血再灌流肾组织ET1基因表达及分泌明显增强,主要分布在血管内皮细胞及平滑肌细胞、系膜细胞、肾小管上皮细胞。其分布特点与细胞类型和活性有关。本实验结果提示了缺血再灌注肾内ET1的变化规律。 相似文献
83.
84.
BACKGROUND: Chronic mucocutaneous candidiasis (CMC) is a rare disorder characterized by persistent or recurrent candidal infections of the skin, nails and mucous membranes or by a variable combination of endocrine failure as well as immunodeficiency. Oral clinicopathological features of CMC have seldom been described in detail. METHODS: Seven patients with CMC were reported in the study. The clinical and histological findings, etiological Candida species, immunological evaluation, and therapeutic pattern of oral lesions, were analyzed. RESULTS: Long-standing whitish hyperplastic and nodule-like lesions with exaggerated deep fissure were the typical and characteristic oral manifestations presented by all patients. The tongue was the most common site affected. Histologically, no obvious distinction was found between CMC and other forms of candidal infection. Abnormal proportions of T-lymphocyte subsets and positive titers of autoantibody were observed in three subjects (42.9%) and one patient (14.3%) respectively. Meanwhile, four subjects (57.1%) showed decreased albumin and increased globulin, three cases (42.9%) had high levels of ESR. But no iron deficiency was found. Candida albicans was the microorganism isolated from these patients. CONCLUSIONS: Multiple and widespread candidal infectious lesions can be observed on the oral cavity of CMC patients. Hyperplastic and nodule-like lesion with irremovable whitish patches and deep fissure are the most common oral manifestations of these patients. Dentists, otolaryngologists and pediatricians should be familiar with the clinical appearances of CMC to make an accurate diagnosis. Potential systemic disorders should be concerned to avoid the reoccurrence of oral candidiasis. 相似文献
85.
停跳或不停跳心脏手术对血清 S-100B蛋白表达的影响 总被引:2,自引:1,他引:1
【目的】研究心脏手术围术期血清S-100B蛋白表达及其与停跳或不停跳心肺转流方式和时间的关系。【方法】体外循环心脏手术患者23例,测转流前、转流10min、转流末、转流后24h的血清S-100B蛋白表达水平。【结果】①血清S-100B蛋白质量浓度在体外循环前后动态变化:转流前(M)为0.27μg/L,转流10min后升至0.57μg/L(P<0.01),转流末达峰值1.80μg/L(P<0.01),转流后24h降为0.22μg/L(P>0.05)。转流末的血清S-100B蛋白质量浓度与转流时间呈正相关(r=0.488,P<0.05)。②停跳组(n=6)转流前、转流10min、转流末、转流后24h平均血清S-100B蛋白质量浓度分别为(0.17±0.09)μg/L、(0.48±0.13)μg/L、(1.65±0.52)μg/L和(0.19±0.04)μg/L,不停跳组(n=6)分别为(0.26±0.14)μg/L、(0.71±0.41)μg/L、(1.59±0.84)μg/L和(0.23±0.11)μg/L,两组差别无统计学意义(P>0.05)。【结论】体外循环可导致血清S-100B蛋白表达增高,其表达水平与心肺转流时间呈正相关,但与停跳或不停跳转流方式无关。 相似文献
86.
目的:探讨经尿道等离子前列腺双极汽化电切术(TUPKVP)治疗前列腺增生的效果。方法:回顾性分析580例良性前列腺增生(BPH)患者行TUPKVP的临床资料。结果:中转开放手术2例,切除前列腺组织10~80 g,平均32.5 g。手术时间25~150 min,平均60 min,术中输血10例,无电切综合征(TURS)发生。术后随访2~36个月,患者最大尿流率升高,IPSS症状评分值降低,排尿通畅,疗效好,并发症少。结论:TUPKVP出血少,手术安全,疗效确切,是治疗前列腺增生的有效方法。 相似文献
87.
PURPOSE: To examine the relationship between ametropia and optical aberrations in a population of 200 normal human eyes with refractive errors spanning the range from +5.00 to -10.00 D. METHODS: Using a reduced-eye model of ametropia, we tested the hypothesis that the optical system of the eye is uncorrelated with the degree of ametropia. These predictions were evaluated experimentally with a Shack-Hartmann aberrometer that measured the monochromatic aberrations across the central 6 mm of the dilated pupil in well-corrected, cyclopleged eyes. RESULTS: Optical theory predicted, and control experiments on a model eye verified, that Shack-Hartmann measurements of spherical aberration will vary with axial elongation of the eye even if the dioptric components of the eye are fixed. Contrary to these predictions, spherical aberration was not significantly different from emmetropic eyes. Root mean square of third-order aberrations, fourth-order aberrations, and total higher aberrations (third to 10th) in myopic and hyperopic eyes were also uncorrelated with refractive error. Astigmatic eyes tended to have larger total higher-order aberrations than nonastigmatic eyes. CONCLUSIONS: We conclude that a reduced-eye model of myopia assuming fixed optical parameters and variable axial length is not tenable. 相似文献
88.
Xin Hong Larry N Thibos Arthur Bradley Russell L Woods Raymond A Applegate 《Optometry and vision science》2003,80(1):15-25
Repeated measures of wavefront aberrations were taken along the line-of-sight of seven eyes using two instruments: an objective, cross-cylinder aberroscope (OA) and a Shack-Hartmann (SH) aberrometer. Both instruments were implemented on the same optical table to facilitate interleaved measurements on the same eyes under similar experimental conditions. Variability of repeated measures of individual coefficients tended to be much greater for OA data than for SH data. Although Zernike coefficients obtained from a single measurement were generally larger when measured with the OA than with the SH, the averages across five trials were often smaller for the OA. The Zernike coefficients obtained from the two instruments were not significantly correlated. Radial modulation-transfer functions and point-spread functions derived from the two sets of measurements were similar for some subjects, but not all. When average Zernike coefficients were used to determine optical quality, the OA indicated superior optics in some eyes, but the reverse trend was true if Zernike coefficients from individual trials were used. Possible reasons for discrepancies between the OA and SH measurements include difference in sampling density, quality of data images, alignment errors, and temporal fluctuations. Multivariate statistical analysis indicated that the SH aberrometer discriminated between subjects much better than did the objective aberroscope. 相似文献
89.
异体造血干细胞移植的重要并发症是移植物抗宿主病(GVHD),免疫抑制剂是有效防治GVHD的一类药物.在异体造血干细胞移植后应用免疫抑制剂,使得GVHD发生率下降,严重程度减轻.本文对几类主要的免疫抑制剂的作用机理以及在异体造血干细胞移植中作为预防和治疗GVHD的应用作一综述. 相似文献
90.
Anatomic and spiral computed tomographic study of the genial tubercles for genioglossus advancement.
Shan Kai Yin Hong Liang Yi Wen Ying Lu Jian Guan Hong Min Wu Zhen Yu Cao Dong Zhen Yu Yan Yan Huang Chun Gen Wu 《Otolaryngology--head and neck surgery》2007,136(4):632-637
OBJECTIVE: To measure and compare Chinese mandibular genial tubercles measured anatomically and with computed tomography (CT). STUDY DESIGN AND SETTING: Spiral CT scans were taken of 40 adult human skulls; the superior genial spines were measured using anatomic and CT methods. RESULTS: The height and width of the superior genial spines, mandible thickness, and distance from the menton to the inferior and superior margins of the superior genial spines were 5.82 +/- 0.71, 6.98 +/- 1.35, 11.95 +/- 1.59, 11.08 +/- 2.05, and 16.91 +/- 2.30 mm from anatomic measurements and 6.17 +/- 0.71, 7.01 +/- 1.13, 12.19 +/- 1.64, 10.41 +/- 1.55, and 15.73 +/- 2.12 mm using spiral CT, respectively. The anatomic and CT measurements were correlated. CONCLUSION: Spiral CT of the genial tubercles can help locate the osteotomy in genioglossus advancement. SIGNIFICANCE: This study acquired reference data on Chinese genial tubercles demonstrating that CT measurements of the genial tubercles reflect their anatomy, which should allow accurately locate the osteotomy. 相似文献