全文获取类型
收费全文 | 313393篇 |
免费 | 43088篇 |
国内免费 | 3027篇 |
专业分类
耳鼻咽喉 | 6826篇 |
儿科学 | 9416篇 |
妇产科学 | 5323篇 |
基础医学 | 25469篇 |
口腔科学 | 5068篇 |
临床医学 | 42432篇 |
内科学 | 80840篇 |
皮肤病学 | 10732篇 |
神经病学 | 29490篇 |
特种医学 | 13426篇 |
外国民族医学 | 14篇 |
外科学 | 66613篇 |
综合类 | 2786篇 |
现状与发展 | 72篇 |
一般理论 | 113篇 |
预防医学 | 19163篇 |
眼科学 | 6809篇 |
药学 | 11642篇 |
1篇 | |
中国医学 | 322篇 |
肿瘤学 | 22951篇 |
出版年
2024年 | 754篇 |
2023年 | 5597篇 |
2022年 | 2761篇 |
2021年 | 6556篇 |
2020年 | 8034篇 |
2019年 | 5430篇 |
2018年 | 10965篇 |
2017年 | 10021篇 |
2016年 | 11465篇 |
2015年 | 11965篇 |
2014年 | 20440篇 |
2013年 | 22390篇 |
2012年 | 16273篇 |
2011年 | 17003篇 |
2010年 | 16718篇 |
2009年 | 20054篇 |
2008年 | 15889篇 |
2007年 | 14594篇 |
2006年 | 16907篇 |
2005年 | 14317篇 |
2004年 | 12728篇 |
2003年 | 11022篇 |
2002年 | 10679篇 |
2001年 | 6306篇 |
2000年 | 5133篇 |
1999年 | 5533篇 |
1998年 | 5531篇 |
1997年 | 4978篇 |
1996年 | 4629篇 |
1995年 | 4417篇 |
1994年 | 3050篇 |
1993年 | 2562篇 |
1992年 | 2757篇 |
1991年 | 2673篇 |
1990年 | 2209篇 |
1989年 | 2258篇 |
1988年 | 2015篇 |
1987年 | 1841篇 |
1986年 | 1843篇 |
1985年 | 1635篇 |
1984年 | 1509篇 |
1983年 | 1333篇 |
1982年 | 1469篇 |
1981年 | 1282篇 |
1980年 | 1100篇 |
1979年 | 1006篇 |
1978年 | 1001篇 |
1977年 | 947篇 |
1976年 | 760篇 |
1974年 | 750篇 |
排序方式: 共有10000条查询结果,搜索用时 798 毫秒
991.
Q-Switched Alexandrite Laser Therapy for Pigmentation of the Lips Owing to Laugier-Hunziker Syndrome 总被引:2,自引:0,他引:2
Ozawa Toshiyuki MD Fujiwara Masao MD † Harada Teruichi MD Muraoka Michinari MD Ishii Masamitsu MD 《Dermatologic surgery》2005,31(6):709-712
BACKGROUND: Laugier-Hunziker (LH) syndrome is a rare benign condition in which hyperpigmentation of the lips and buccal mucosa occurs with no systemic associations. OBJECTIVE: We report the response to treatment with the Q-switched alexandrite laser (QSAL) because there are few reports on therapy for LH syndrome. METHODS: The QSAL was used for pigmentation of the lips in a 63-year-old woman with LH syndrome. Laser irradiation was done at 5.0 J/cm2 with a 3 mm spot size. RESULTS: There was 100% clearance of pigmentation of the lips with a single laser treatment, and recurrence was not observed after 6 months. CONCLUSION: The QSAL is very effective for pigmentation owing to LH syndrome. 相似文献
992.
The use of 19F spectroscopy and diffusion-weighted MRI to evaluate differences in gene-dependent enzyme prodrug therapies. 总被引:4,自引:0,他引:4
Daniel A Hamstra Kuei C Lee Joseph M Tychewicz Victor D Schepkin Bradford A Moffat Mark Chen Kenneth J Dornfeld Theodore S Lawrence Thomas L Chenevert Brian D Ross Juri T Gelovani Alnawaz Rehemtulla 《Molecular therapy》2004,10(5):916-928
To evaluate noninvasive measures of gene expression and tumor response in a gene-dependent enzyme prodrug therapy (GDEPT), a bifunctional fusion gene between Saccharomyces cerevisiae cytosine deaminase (CD) and Haemophilus influenzae uracil phosphoribosyltransferase (UPRT) was constructed. CD deaminates 5-fluorocytosine (5FC) to 5-fluorouracil (5FU), and UPRT subsequently converts 5FU to fluorouridine monophosphate, and both of these reactions can be monitored noninvasively in vitro and in vivo using 19F magnetic resonance spectroscopy (MRS). Following transient transfection the CD-UPRT fusion protein exhibited both UPRT and CD enzymatic activities as documented by 19F MRS. In addition, an increase in CD activity and thermal stability was witnessed for the fusion protein compared to native CD. Stable expression of CD-UPRT in 9L glioma cells increased both 5FC and 5FU sensitivity in vitro compared to CD-expressing and wild-type 9L cells. Noninvasive 19F MRS of both CD and UPRT gene function in vivo demonstrated that in animals bearing CD-expressing tumors there was limited conversion of 5FC to 5FU with no measurable accumulation of cytotoxic fluorinated nucleotides (F-nucs). In contrast, CD-UPRT-expressing tumors had increased CD gene activity with a threefold higher intratumoral accumulation of 5FU and significant generation of F-nucs. Finally, CD-UPRT yielded increased efficacy in an orthotopic animal model of high-grade glioma. More importantly, early changes in cellular water mobility, which are felt to reflect cellular death, as measured by diffusion-weighted MRI, were predictive of both durable response and increased animal survival. These results demonstrate the increased efficacy of the CD-UPRT GDEPT compared to CD alone both biochemically and in a preclinical model and validate both 19F MRS and diffusion-weighted MRI as tools to assess gene function and therapeutic efficacy. 相似文献
993.
994.
995.
996.
997.
998.
999.
1000.
Felix Eckstein Maiko Matsuura Volker Kuhn Mathias Priemel Ralph Müller Thomas M Link Eva-Maria Lochmüller 《Journal of bone and mineral research》2007,22(6):817-824
In this study, we characterize bone microstructure, specifically sex differences, at multiple skeletal sites in 165 subjects >52 yr of age, using microCT technology in vitro. Significant sex differences are observed at the distal radius, femoral neck, and femoral trochanter, but not at the iliac crest, calcaneus, and lumbar vertebral body. Correlations in BV/TV between sites ranged from r = 0.13 to 0.56. INTRODUCTION: The goals of this study were (1) to assess potential sex differences of bone microstructure and their difference between skeletal sites and (2) to explore the relationship of trabecular microstructural properties between relevant skeletal sites. MATERIALS AND METHODS: Trabecular bone microstructural properties were measured in vitro in 165 subjects 52-99 yr of age using microCT. Defined volumes of interest (cylinders with 6 mm diameter and 6 mm length) were scanned at a resolution of 26 microm (isotropic) in six different anatomical sites: distal radius, femoral neck and trochanter, iliac crest, calcaneus, and second lumbar vertebral body. RESULTS: At the radius and femoral neck, trabecular bone displayed a more plate-like structure, thicker trabeculae, smaller separation/higher trabecular number, higher connectivity, and a higher degree of anisotropy in men than in women (p < 0.05). At the trochanter, men displayed more plate-like structure and thicker trabeculae (p < 0.05), but no differences in trabecular separation or other parameters compared with the women. At the calcaneus, iliac crest, and second lumbar vertebra none of the bone parameters displayed significant differences between sexes. The BV/TV at one site explained a range of only 2-32% of the variability at other sites. CONCLUSIONS: These results suggest that trabecular bone microstructural properties are remarkably heterogeneous throughout the skeleton. Significant differences between men and women are observed at some, but not at all, sites. The magnitude of sex differences in trabecular microstructure coincides with that of fracture incidence observed for some of the sites in epidemiological studies. 相似文献