全文获取类型
收费全文 | 3109198篇 |
免费 | 216854篇 |
国内免费 | 4530篇 |
专业分类
耳鼻咽喉 | 43460篇 |
儿科学 | 101429篇 |
妇产科学 | 83591篇 |
基础医学 | 452851篇 |
口腔科学 | 86282篇 |
临床医学 | 279965篇 |
内科学 | 595232篇 |
皮肤病学 | 69132篇 |
神经病学 | 241876篇 |
特种医学 | 117722篇 |
外国民族医学 | 676篇 |
外科学 | 467316篇 |
综合类 | 63871篇 |
现状与发展 | 13篇 |
一般理论 | 1056篇 |
预防医学 | 236712篇 |
眼科学 | 73218篇 |
药学 | 237422篇 |
18篇 | |
中国医学 | 6679篇 |
肿瘤学 | 172061篇 |
出版年
2021年 | 24799篇 |
2019年 | 24986篇 |
2018年 | 34746篇 |
2017年 | 26406篇 |
2016年 | 29855篇 |
2015年 | 33419篇 |
2014年 | 46871篇 |
2013年 | 70042篇 |
2012年 | 96123篇 |
2011年 | 102220篇 |
2010年 | 60633篇 |
2009年 | 57032篇 |
2008年 | 95345篇 |
2007年 | 101689篇 |
2006年 | 102679篇 |
2005年 | 99044篇 |
2004年 | 94928篇 |
2003年 | 91439篇 |
2002年 | 88414篇 |
2001年 | 146223篇 |
2000年 | 150384篇 |
1999年 | 126192篇 |
1998年 | 35587篇 |
1997年 | 31243篇 |
1996年 | 31557篇 |
1995年 | 29677篇 |
1994年 | 27293篇 |
1993年 | 25740篇 |
1992年 | 97161篇 |
1991年 | 94461篇 |
1990年 | 92616篇 |
1989年 | 89090篇 |
1988年 | 81670篇 |
1987年 | 80058篇 |
1986年 | 75179篇 |
1985年 | 71668篇 |
1984年 | 53050篇 |
1983年 | 45081篇 |
1982年 | 26311篇 |
1979年 | 48554篇 |
1978年 | 34144篇 |
1977年 | 29066篇 |
1976年 | 27058篇 |
1975年 | 29610篇 |
1974年 | 35118篇 |
1973年 | 33612篇 |
1972年 | 31799篇 |
1971年 | 30027篇 |
1970年 | 27664篇 |
1969年 | 26479篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
Barbara A. Bresnahan Christopher P. Johnson Matthew J. McIntosh Donald Stablein Sundaram Hariharan 《American journal of transplantation》2002,2(4):366-372
The optimal allocation of cadaveric kidneys for transplantation with reference to human leukocyte antigen (HLA) match and sharing these organs to a distant center remains controversial. The current analysis was performed using the United Network for Organ Sharing (UNOS) database for cadaveric kidney transplants (Tx) between 1988 and 1997. The graft survivals of zero-mismatch (matched) kidneys with the mate (mismatched) kidneys were compared. There were 2385 donors and 4770 Tx. Significant differences in recipient demographics between matched and mismatched Tx were: fewer African-American race (AA) in the matched group (9.0% vs. 21.9%), higher number of previous Tx (25.5% vs. 14.8%) and elevated mean cold ischemia time (24.0 vs. 22.2 h). Post-Tx dialysis requirements were similar (22.8% vs. 24.1%, p = 0.62) and matched kidneys had to travel more distance (920 vs. 232 miles). Using a Cox model, the matched group had a decreased relative hazard of graft failure of 23.0% (p = 0.0002) or 35% (p < 0.0001) with and without censoring for death. There was significantly better graft survival in the matched recipients in all pairs except AA (matched) and non-AA (mismatched). For older donors (> or = 50 years, n = 1508), the matched grafts survival was marginally significant (p =0.05). Matched kidneys have improved survival compared with the mismatched kidneys despite the longer distance traveled. The benefit of mismatched transplants was predominantly seen in non-AA. 相似文献
994.
995.
Penetration and distribution of three lipophilic probes in vitro in human skin focusing on the hair follicle. 总被引:2,自引:0,他引:2
Fluorescent model substances of increasing lipophilicity (Oregon Green) 488, Bodipy, FL C5 and Bodipy 564/570 C5) were selected to enable the visualization in the skin using confocal laser scanning microscopy. After measuring the penetration for 18 h, the nonfixed human scalp skin was imaged from the bottom parallel to the stratum corneum and in a cross-section view perpendicular to the skin surface. The images were evaluated by calculating relative accumulation values for different penetrants. The studies indicate that the penetrated amount is highest for Bodipy FL C5 (medium lipophilicity) and lowest for Bodipy 564/570 C5 (high lipophilicity) whereas Bodipy 564/570 C5 (high lipophilicity) reveals the highest relative accumulation in parts of the hair follicle compared to Oregon Green 488 (low lipophilicity). The addition of 30% (v/v) ethanol to the donor phase of substance with a low lipophilicity increases the follicular delivery. From our results we conclude that delivery to the hair follicle can be improved by increasing the drugs lipophilicity and optimizing the composition of the donor phase. However, no conclusion can be drawn about the actual route of transport to the hair follicle. 相似文献
996.
M. Wensing A. H. Penninks† S. L. Hefle‡ J. H. Akkerdaas§ R. van Ree§ S. J. Koppelman† C. A. F. M. Bruijnzeel-Koomen A. C. Knulst 《Clinical and experimental allergy》2002,32(12):1757-1762
BACKGROUND: The risk for allergic reactions depends on the sensitivity of individuals and the quantities of offending food ingested. The sensitivity varies among allergic individuals, as does the threshold dose of a food allergen capable of inducing an allergic reaction. OBJECTIVE: This study aimed at determining the distribution of minimum provoking doses of hazelnut in a hazelnut-allergic population. METHODS: Thirty-one patients with a history of hazelnut-related allergic symptoms, a positive skin prick test to hazelnut and/or an elevated specific IgE level, were included. Double-blind, placebo-controlled food challenges (DBPCFC) were performed with seven increasing doses of dried hazelnut (1 mg to 1 g hazelnut protein) randomly interspersed with seven placebo doses. RESULTS: Twenty-nine patients had a positive challenge. Itching of the oral cavity and/or lips was the first symptom in all cases. Additional gastrointestinal symptoms were reported in five patients and difficulty in swallowing in one patient. Lip swelling was observed in two patients, followed by generalized urticaria in one of these. Threshold doses for eliciting subjective reactions varied from a dose of 1 mg up to 100 mg hazelnut protein (equivalent to 6.4-640 mg hazelnut meal). Extrapolation of the dose-response curve showed that 50% of our hazelnut-allergic population will suffer from an allergic reaction after ingestion of 6 mg (95% CI, 2-11 mg) of hazelnut protein. Objective symptoms were observed in two patients after 1 and 1,000 mg, respectively. CONCLUSION: DBPCFCs demonstrated threshold doses in half of the hazelnut-allergic patients similar to doses previously described to be hidden in consumer products. This stresses the need for careful labelling and strategies to prevent and detect contamination of food products with hazelnut residues. 相似文献
997.
998.
999.
Regulations evolve and risks management becomes one of the biomedical engineers' preoccupations. Thus, risks are various, and consequently it is difficult to identify, to manage and to bring them under control. Furthermore, regulations exist for sectors like healthcare technology monitoring, but it is not the same thing for instance for the risks linked to the maintenance. Thus regulation in the sector of maintenance evolves and the decree of the 1st July law of health safety is going to modify the biomedical environment. The goal of this work is to study the tools and the methods of risks management that have been used for several years in the industrial field and to use them for some biomedical equipment like monitors or IV pumps. These methods adapted to these equipment will allow us to determine some appropriate rules of maintenance. 相似文献
1000.
D. Lothschütz M. Jennewein S. Pahl H.F. Lausberg A. Eichler W. Mutschler R.G. Hanselmann M. Oberringer 《Inflammation research》2002,51(8):416-422
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi. 相似文献