全文获取类型
收费全文 | 192390篇 |
免费 | 1990篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 1195篇 |
儿科学 | 7012篇 |
妇产科学 | 3204篇 |
基础医学 | 18633篇 |
口腔科学 | 2262篇 |
临床医学 | 14035篇 |
内科学 | 34653篇 |
皮肤病学 | 1030篇 |
神经病学 | 18298篇 |
特种医学 | 9694篇 |
外科学 | 31551篇 |
综合类 | 2414篇 |
一般理论 | 4篇 |
预防医学 | 19124篇 |
眼科学 | 2845篇 |
药学 | 10589篇 |
中国医学 | 645篇 |
肿瘤学 | 17273篇 |
出版年
2023年 | 145篇 |
2022年 | 156篇 |
2021年 | 389篇 |
2020年 | 291篇 |
2019年 | 413篇 |
2018年 | 22336篇 |
2017年 | 17756篇 |
2016年 | 19866篇 |
2015年 | 1364篇 |
2014年 | 1425篇 |
2013年 | 1763篇 |
2012年 | 8219篇 |
2011年 | 22130篇 |
2010年 | 19488篇 |
2009年 | 12190篇 |
2008年 | 20516篇 |
2007年 | 22772篇 |
2006年 | 1653篇 |
2005年 | 3229篇 |
2004年 | 4276篇 |
2003年 | 5239篇 |
2002年 | 3335篇 |
2001年 | 416篇 |
2000年 | 506篇 |
1999年 | 287篇 |
1998年 | 382篇 |
1997年 | 397篇 |
1996年 | 230篇 |
1995年 | 237篇 |
1994年 | 235篇 |
1993年 | 194篇 |
1992年 | 143篇 |
1991年 | 189篇 |
1990年 | 214篇 |
1989年 | 166篇 |
1988年 | 136篇 |
1987年 | 120篇 |
1986年 | 97篇 |
1985年 | 110篇 |
1984年 | 91篇 |
1983年 | 99篇 |
1982年 | 106篇 |
1981年 | 76篇 |
1980年 | 100篇 |
1979年 | 58篇 |
1978年 | 73篇 |
1977年 | 58篇 |
1975年 | 56篇 |
1938年 | 60篇 |
1932年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
51.
52.
Jaafar Mouhyi Lars Sennerby Jeanjacques Pireaux Nicolas Dourov Samir Nammour Jack Van Reck 《Clinical oral implants research》1998,9(3):185-194
The purpose of the present study was to analyse clinically failed and retrieved implants prior to and after cleaning by means of scanning electron microscopy (SEM) and X-ray induced photoelectron spectroscopy (XPS) as compared to unused controls. Six different chemical and physical techniques for cleaning of contaminated titanium implants were evaluated: 1) rinsing in absolute ethanol for 10 min, 2) cleaning in ultrasonic baths containing trichloroethylene (TRI) and absolute ethanol, 10 min in each solution, 3) abrasive cleaning for 30 s, 4) cleaning in supersaturated citric acid for 30 s, 5) cleaning with continuous CO2-laser in dry conditions at 5 W for 10 s, 6) cleaning with continuous CO2-laser in wet conditions (saline) at 5 W for 10 s. SEM of failed implants showed the presence of contaminants of varying sizes and XPS showed almost no titanium but high carbon signals. XPS of unused titanium implants showed lower levels of titanium as previously reported, probably due to contamination of carbon which increased with time in room air. Cleaning of used implants in citric acid followed by rinsing with deionized water for 5 min followed by cleaning in ultrasonic baths with TRI and absolute ethanol gave the best results with regard to macroscopical appearance and surface composition. However, as compared to the unused implants the results from an element composition point of view were still unsatisfactory. It is concluded that further development and testing of techniques for cleaning of organically contaminated titanium is needed. 相似文献
53.
54.
Lars Frisén 《Documenta ophthalmologica. Advances in ophthalmology》1988,70(4):323-330
Perimetry suffers from considerable variability of results. A new technique for estimating individual criterion levels in normal subjects exposes the important role of psychological variables. The analysis depends on features peculiar to acuity perimetry. It can be accommodated in the regular examination. The results can be used to compensate for practice effects in serial examinations and to tighten the range of normal limits. The reduction in variation between normal subjects amounted to 57 per cent. 相似文献
55.
G. Vacca E. Marano V. Brescia Morra R. Lanzillo M. De Vito E. Parente G. Orefice 《Neurological sciences》2007,28(3):133-135
The prevalence of primary headache (PH) in a multiple sclerosis (MS) sample vs. control healthy subjects was investigated at a neurological clinic in 2004–2005: 122 of 238 (51%) MS patients and 57 of
238 (23%) controls proved to be affected by headache. The groups did not differ for the rates of PH types. Headache types
of MS patients were comparable to those of PH patients that were observed at the same institute in a case-control comparison.
First symptoms of headache preceded those of MS in two thirds of cases. Headache features did not significantly change after
MS onset. Comorbidity of MS and PH could be explained by some common clinical and biological traits. 相似文献
56.
Volker Heinemann 《Breast cancer research and treatment》2003,81(1):43-48
Single-agent chemotherapy of metastatic breast cancer is the treatment of choice in patients with slow tumor progression and asymptomatic disease. In this patient group, the choice of drugs is based more on good tolerability than on efficacy. By contrast, symptomatic or rapidly progressing disease requires the use of highly active regimens where more weight is put on reliable antitumor activity. While anthraycline-based combination regimens have set the standard of effective treatment, the addition of docetaxel (and to a lesser extent paclitaxel) has improved tumor response, but failed to induce a consistent prolongation of survival. Based on retrospective analyses, it is hypothesised that the combined use of anthracyclines and taxanes in first-line therapy may be most beneficial in defined subgroups: after adjuvant chemotherapy, in patients with HER-2 gene amplification, possibly also in patients with rapidly progressing visceral disease. 相似文献
57.
58.
Ohne Zusammenfassung 相似文献
59.
Katarina M?rtensson Dionisios Chrysis Lars S?vendahl 《Journal of bone and mineral research》2004,19(11):1805-1812
We hypothesized that pro-inflammatory cytokines can act locally in the growth plate to impair longitudinal growth. In a model of cultured fetal rat metatarsal bones, we found that IL-1beta and TNF-alpha act in synergy to inhibit longitudinal growth, an effect linked to decreased proliferation and increased apoptosis of growth plate chondrocytes. IGF-I could partially reverse all these effects. INTRODUCTION: Children with chronic inflammatory conditions, such as Crohn's disease or rheumatoid arthritis, experience impaired longitudinal growth. The inflammatory process itself, which includes upregulation of the pro-inflammatory cytokines interleukin (IL)-1beta, IL-6, and TNF-alpha, is believed to be at least partly responsible for the poor growth in these patients. This study aimed to clarify whether these cytokines can act locally in the growth plate to suppress longitudinal growth and whether any negative effects can be reversed by insulin-like growth factor-I (IGF-I). MATERIALS AND METHODS: The effects of cytokines on longitudinal bone growth were studied in fetal (day E20) rat metatarsal bones kept in culture. After a 7-day culture, the bones were sectioned, and chondrocyte proliferation was assessed by bromodeoxyuridine (BrdU) incorporation and apoptosis by TUNEL. RESULTS: When added separately, IL-1beta and TNF-alpha impaired longitudinal bone growth only at a high concentration (100 ng/ml each; p < 0.05 versus control). In contrast, when added in combination, IL-1beta and TNF-alpha potently inhibited growth at far lower concentrations (from 3 ng/ml each; p < 0.001 versus control) and also decreased chondrocyte proliferation and increased apoptosis. Growth failure induced by the combination of IL-1beta and TNF-alpha (10 ng/ml each) could be counteracted by anti-IL-1beta (100 ng/ml; p < 0.001), anti-TNF-alpha (100 ng/ml; p < 0.001), or IGF-I (100 ng/ml; p < 0.01). IL-6 did not affect longitudinal growth even when added in combination with IL-1beta or TNF-alpha (10 ng/ml each). CONCLUSIONS: We show that IL-1beta and TNF-alpha act in synergy to locally suppress longitudinal growth, an effect that can be partially reversed by IGF-I. Although growth hormone (GH)/IGF-I may improve longitudinal growth in children with chronic inflammatory diseases, our results suggest that the inflammatory process itself must be targeted to achieve normal growth. 相似文献
60.