全文获取类型
收费全文 | 69891篇 |
免费 | 6000篇 |
国内免费 | 2177篇 |
专业分类
耳鼻咽喉 | 715篇 |
儿科学 | 1444篇 |
妇产科学 | 1124篇 |
基础医学 | 9151篇 |
口腔科学 | 1595篇 |
临床医学 | 7127篇 |
内科学 | 13167篇 |
皮肤病学 | 1088篇 |
神经病学 | 5813篇 |
特种医学 | 2354篇 |
外国民族医学 | 14篇 |
外科学 | 9468篇 |
综合类 | 5946篇 |
现状与发展 | 6篇 |
一般理论 | 35篇 |
预防医学 | 4868篇 |
眼科学 | 1655篇 |
药学 | 6054篇 |
15篇 | |
中国医学 | 1294篇 |
肿瘤学 | 5135篇 |
出版年
2023年 | 462篇 |
2022年 | 972篇 |
2021年 | 1639篇 |
2020年 | 1119篇 |
2019年 | 1259篇 |
2018年 | 1570篇 |
2017年 | 1305篇 |
2016年 | 1309篇 |
2015年 | 1712篇 |
2014年 | 2209篇 |
2013年 | 2690篇 |
2012年 | 3870篇 |
2011年 | 3928篇 |
2010年 | 2509篇 |
2009年 | 2104篇 |
2008年 | 3271篇 |
2007年 | 3507篇 |
2006年 | 3385篇 |
2005年 | 3147篇 |
2004年 | 2679篇 |
2003年 | 2494篇 |
2002年 | 2285篇 |
2001年 | 3018篇 |
2000年 | 2821篇 |
1999年 | 2497篇 |
1998年 | 1154篇 |
1997年 | 898篇 |
1996年 | 730篇 |
1995年 | 621篇 |
1994年 | 525篇 |
1993年 | 456篇 |
1992年 | 1343篇 |
1991年 | 1189篇 |
1990年 | 1134篇 |
1989年 | 1146篇 |
1988年 | 1067篇 |
1987年 | 992篇 |
1986年 | 936篇 |
1985年 | 830篇 |
1984年 | 614篇 |
1983年 | 545篇 |
1982年 | 413篇 |
1981年 | 351篇 |
1980年 | 336篇 |
1979年 | 418篇 |
1978年 | 253篇 |
1977年 | 219篇 |
1976年 | 224篇 |
1974年 | 237篇 |
1973年 | 226篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
S. Friedman R. Komorowski W. Maillet H. Q. Nguyen C. D. Torneck 《Dental traumatology》1998,14(5):225-231
Abstract— NdYAG laser-induced modification of the root surface may inhibit development of external inflammatory resorption in replanted teeth. This study tested this hypothesis in vivo. The pulp chambers of six mandibular premolars in each of two dogs were accessed, inoculated with plaque, and sealed (Groups 1, 2). Two additional premolars in each dog were endodontically treated without inoculation (Groups 3, 4). After 2 weeks, teeth were hemisected and extracted. Each root had a 2times3 mm surface area denuded of cementum on the buccal and lingual surface. In Groups 1 (n= 12 roots) and 3 (n=4), the denuded surfaces were wiped with 15% EDTA, coated with black ink, and irradiated with Nd:YAG laser (0.75 W, 15 ppc, 300 pm tip, 20 s). In Groups 2 (n= 12) and 4 (n= 4), the surfaces were wiped with 15% EDTA, and rinsed with sterile saline for 20 s. Roots were replanted within 5 min. The dogs were perfwion-euthanised 10 weeks after replantation. Block specimens were removed, decalcified, embedded and horizontally sectioned (6 pm) at 180-pm intervals, resulting in 10 to 14 cross-sections of each root. From these, the middle five consecutive sections were stained with hematoxylin and eosin, and observed by light microscopy for occurrence of surface, inflammatory and replacement resorption on the denuded surfaces. No obvious differences were noted between the laser-irradiated and non-irradiated surfaces. Inflammatory resorption was frequent in Groups 1 and 2, and absent in Groups 3 and 4. Replacement resorption was minimal in Groups 1 and 2, and frequent in Groups 3 and 4. Differences between Groups 1 and 2, and between Groups 3 and 4 were not significant, whereas the differences between the two pairs of groups were statistically significant (chi-square and two-way ANOVA, P>0.006). These results did not support the hypothesis, and questioned the clinical validity of the surface modification in NdYAG laser-irradiated den-tin. Therefore, the clinical application of NdYAG laser to the root surfaces of replanted teeth is not warranted. 相似文献
104.
Structural vertebral changes in the horizontal plane in idiopathic scoliosis and the long-term corrective effect of spine instrumentation 总被引:1,自引:0,他引:1
Summary The rotation and structural changes of the apex vertebra in the horizontal plane as well as of the thoracic cage deformity were quantified by measurements on computed tomography (CT) scans from patients with right convex thoracic idiopathic scoliosis (IS). The CT scans were obtained from 12 patients with moderate scoliosis (mean Cobb angle 25.8°, r 13°–30°) and from 33 with severe scoliosis (mean Cobb angle 46.2°, r 35°–71°). In addition, CT scans of thoracic vertebrae from 15 patients without scoliosis were used as reference material. Ten of the scoliotic cases had had Cotrel-Dubousset instrumentation (CDI) and posterior fusion and had entered a longitudinal study on the effect of operative correction on the re-modelling of the apical vertebra. An increasingly asymmetrical vertebral body, transverse process angle, pedicle width and canal width were found in the groups with scoliosis as compared with the reference material. Vertebral rotation and rib hump index were significantly larger in patients with early and advanced scoliosis than in normal subjects. The modelling angle of the vertebral body, the transverse process angle index and the vertebral rotation in relation to the middle axis of the thoracic cage were significantly greater in patients with severe than with moderate scoliosis. The results of this longitudinal study suggest that the structural changes of the apical vertebra regress 2 years or more after CD instrumentation. 相似文献
105.
Q. Peng J. Moan Jahn M. Nesland Jan F. Evensen M. Kongshaug C. Rimington 《Lasers in medical science》1990,5(4):399-409
Observations on time-dependent localization of tetra(3-hydroxyphenyl)porphin (3-THPP) in human malignant melanoma transplanted to athymic nude mice from 1 to 120 h after intraperitoneal (i.p.) 10 mg kg–1 b.w. administration were made by means of fluorescence microscopy. Fluorescence was found on the membrane of the melanoma cells and in the cytoplasm with a peak fluorescence intensity at 24 h post-injection of 3-THPP. The growth of the tumour cells was obviously inhibited at an early stage after PCT. Morphological changes of the tumour at various intervals after treatment by PCT with 3-THPP were also observed. Diffuse degeneration of the tumour cells with swelling of mitochondria and endoplasmic reticulum, heterochromatin aggregation and margination, etc., and subsequently diffuse necrosis with little or no the background of tumorous vascular response were found at an early stage after PCT. On the other hand, it was also observed that the necrosis of the melanoma areas was caused as a consequence of tumorous vascular injury at a later stage after PCT. Thus, two tumoricidal processes caused by PCT with 3-THPP were seen: a direct phototoxic action on tumour cells at an early stage after PCT and an indirect effect secondary to tumorous vascular injury at a later period after PCT. 相似文献
106.
Poverty, health services, and health status in rural America 总被引:5,自引:0,他引:5
Access to health services for everyone has been a major policy goal in the United States: inequitable access is assumed to lead to inequitable health status, particularly for low-income groups. A sophisticated model of the relation between poverty, health care needs, service use, and health outcomes is used to analyze cross-sectional data on 7,823 adults from 36 rural communities. Improved access and use are helpful, but evidence clearly indicates that combined health and social initiatives will be necessary to reduce inequalities in health status. 相似文献
107.
钙拮抗剂TMB-8抑制BHQ,NE和KCl引起的培养乳牛基底动脉单个平滑肌细胞内游离钙的升高 总被引:1,自引:0,他引:1
用AR CM MIC阳离子测定系统,测量单个细胞内游离钙浓度([Ca2+]i),研究8-(N,N-二乙胺)-n-辛基 3,4,5-三甲氧基苯甲酸酯(TMB-8)对培养乳牛基底动脉平滑肌[Ca2+]i的作用。在细胞外钙浓度为1.3mmol·L-1时,TMB-8(30μmol·L-1)可明显抑制BHQ,NE及KCl引起[Ca2+]i的升高。在细胞外钙为零+EGTA 0.1mmol·L-1时,TMB-8(10,30及100μmol·L-1)可浓度依赖性地降低静息[Ca2+]i,TMB-8(30μmol·L-1)可几乎完全阻断BHQ及NE引起[Ca2+]i的增加。研究表明TMB-8降低培养乳牛基底动脉平滑肌[Ca2+]i的机制,主要是抑制肌浆网Ca2+的释放,或增加肌浆网对Ca2+的摄入,并由此间接地抑制细胞外钙的内流。 相似文献
108.
Dr W. Q. Ge Z. C. Luo J. Jin Y. C. Huang S. Wang S. J. Lui 《Medical & biological engineering & computing》1998,36(1):22-26
A novel cardiokymograph system is introduced. The new system features a capacitance transducer with increased sensitivity
and can be used in multichannel measurements. The novelty of this technique is the injection of a current into the patient
coupled with the use of a capacitive displacement transducer and the possibility of multichannel monitoring. It provides for
the possibility of removing breath noise when some signal processing technique, such as adaptive filtering, is used. Further
investigation is needed to demonstrate clinical significance and pathologies. 相似文献
109.
110.