全文获取类型
收费全文 | 54116篇 |
免费 | 3775篇 |
国内免费 | 177篇 |
专业分类
耳鼻咽喉 | 545篇 |
儿科学 | 1726篇 |
妇产科学 | 1390篇 |
基础医学 | 7764篇 |
口腔科学 | 754篇 |
临床医学 | 7322篇 |
内科学 | 10214篇 |
皮肤病学 | 1038篇 |
神经病学 | 5870篇 |
特种医学 | 1255篇 |
外国民族医学 | 1篇 |
外科学 | 4372篇 |
综合类 | 821篇 |
一般理论 | 46篇 |
预防医学 | 5815篇 |
眼科学 | 1220篇 |
药学 | 3726篇 |
中国医学 | 94篇 |
肿瘤学 | 4095篇 |
出版年
2023年 | 323篇 |
2022年 | 631篇 |
2021年 | 1138篇 |
2020年 | 695篇 |
2019年 | 1049篇 |
2018年 | 1228篇 |
2017年 | 990篇 |
2016年 | 1168篇 |
2015年 | 1368篇 |
2014年 | 1783篇 |
2013年 | 2623篇 |
2012年 | 3902篇 |
2011年 | 4065篇 |
2010年 | 2119篇 |
2009年 | 2056篇 |
2008年 | 3658篇 |
2007年 | 3846篇 |
2006年 | 3879篇 |
2005年 | 3802篇 |
2004年 | 3615篇 |
2003年 | 3381篇 |
2002年 | 3135篇 |
2001年 | 461篇 |
2000年 | 338篇 |
1999年 | 454篇 |
1998年 | 592篇 |
1997年 | 522篇 |
1996年 | 463篇 |
1995年 | 430篇 |
1994年 | 314篇 |
1993年 | 340篇 |
1992年 | 239篇 |
1991年 | 234篇 |
1990年 | 197篇 |
1989年 | 190篇 |
1988年 | 208篇 |
1987年 | 162篇 |
1986年 | 155篇 |
1985年 | 162篇 |
1984年 | 201篇 |
1983年 | 195篇 |
1982年 | 247篇 |
1981年 | 186篇 |
1980年 | 192篇 |
1979年 | 119篇 |
1978年 | 117篇 |
1977年 | 116篇 |
1976年 | 94篇 |
1975年 | 76篇 |
1974年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Elizabeth A. Mosley PhD MPH Amy J. Schulz PhD MPH MSW Lisa H. Harris MD PhD Barbara A. Anderson PhD 《Women & health》2020,60(7):806-820
ABSTRACT Abortion is legal in South Africa, but negative abortion attitudes remain common and are poorly understood. We used nationally representative South African Social Attitudes Survey data to analyze abortion attitudes in the case of fetal anomaly and in the case of poverty from 2007 to 2016 (n = 20,711; ages = 16+). We measured correlations between abortion attitudes and these important predictors: religiosity, attitudes about premarital sex, attitudes about preferential hiring and promotion of women, and attitudes toward family gender roles. Abortion acceptability for poverty increased over time (b = 0.05, p < .001), but not for fetal anomaly (b = ?0.008, p = .284). Highly religious South Africans reported lower abortion acceptability in both cases (Odds Ratio (OR)anomaly = 0.85, p = .015; ORpoverty = 0.84, p = .02). Premarital sex acceptability strongly and positively predicted abortion acceptability (ORanomaly = 2.63, p < .001; ORpoverty = 2.46, p < .001). Attitudes about preferential hiring and promotion of women were not associated with abortion attitudes, but favorable attitudes about working mothers were positively associated with abortion acceptability for fetal anomaly ((ORanomaly = 1.09, p = .01; ORpoverty = 1.02, p = .641)). Results suggest negative abortion attitudes remain common in South Africa and are closely tied to religiosity, traditional ideologies about sexuality, and gender role expectations about motherhood. 相似文献
4.
Is it possible to make a diagnosis of raw,heated, and baked egg allergy in children using cutoffs? A systematic review 下载免费PDF全文
5.
6.
7.
Marco Maruzzo Umberto Basso Eugenio Borsatti Laura Evangelista Filippo Alongi Orazio Caffo Francesca Maines Sara Galuppo Rocco De Vivo Fable Zustovich Dario Palleschi Andrea Zivi Teodoro Sava Mariella Sorarù Roberto Iacovelli Maurizio Nicodemo Susanne Baier Lucia Fratino Vittorina Zagonel 《Clinical genitourinary cancer》2019,17(1):e187-e194
Background
Radium 223 was introduced for metastatic castration-resistant prostate cancer based on the results of a randomized controlled trial showing risk reduction for death and skeletal events. Our aim was to evaluate the outcome of patients receiving radium 223 in a real-world setting.Patients and Methods
We conducted a multicenter retrospective analysis in the Triveneto region of Italy.Results
One hundred fifty-eight patients received radium 223 in our region. After a median follow-up of 9.5 months, 75 patients died. The median overall survival (OS) was 14.2 months, and the median progression-free survival (PFS) was 6.2 months. Seventy-one (45%) patients achieved progression as best response. Thirty-seven (23%) patients stopped the treatment early because of progression. Eastern Cooperative Oncology Group performance status was prognostic for OS (18.4 vs. 12.3 vs. 7.5 months; 0 vs. 1, P = .0062; 0 vs. 2, P = .0002), whereas previous prostatectomy or docetaxel exposure were not. A neutrophil to lymphocytes ratio ≥ 3 significantly impacted OS (18.1 vs. 9.7 months; P < .001) and slightly impacted PFS (6.6 vs. 5.6 months; P = .05). Patients with a baseline alkaline phosphatase (ALP) value ≥ 220 U/L had worse OS and PFS (24.1 vs. 10.5 months; 7.2 vs. 5.5 months; P < .001). Patients with changes in ALP value achieved better OS (P = .029) and PFS (P = .002). There was no difference according to the line of therapy (0 vs. ≥ 1; P = .490). The main grade 3/4 toxicities were anemia, asthenia, and thrombocytopenia.Conclusion
This large real-world report confirms comparable OS and PFS data when compared with the pivotal study, as well as the predictive role of ALP and neutrophil to lymphocytes ratio. The definition of the optimal position of radium 223 in the treatment of metastatic castration-resistant prostate cancer has still to be defined. 相似文献8.
Uwe Schneider PhD Antony Lomax Peter Pemler Jürgen Besserer Dieter Ross Norbert Lombriser Barbara Kaser-Hotz 《Strahlentherapie und Onkologie》2006,182(11):647-652
BACKGROUND AND PURPOSE: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. MATERIAL AND METHODS: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. RESULTS: A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). CONCLUSION: By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidence. 相似文献
9.
Hepatic gene downregulation following acute and subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. 总被引:1,自引:0,他引:1
Bladimir J Ovando Chad M Vezina Barbara P McGarrigle James R Olson 《Toxicological sciences》2006,94(2):428-438
Chronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to lead to the development of hepatotoxicity and carcinogenicity in the liver of female rats. In this study, we investigated hepatic gene downregulation in response to acute and subchronic TCDD exposure. We identified 61 probes which exhibited a downregulation of twofold or greater following subchronic (13 weeks) exposure to TCDD. Comparative analysis of the hepatic expression of these 61 probes was conducted with rats subchronically exposed to PeCDF, PCB126, PCB153, and a mixture of PCB126 and PCB153. PCB153 produced little or no alteration in these probes, while the binary mixture mimicked most closely the downregulation observed with TCDD. To discern if the repression of genes within this probe set occur as a primary response to TCDD exposure, we analyzed the early responsiveness of 11 genes at 6, 24, and 72 h following a single exposure to TCDD. We observed early repression of the 11 genes within this early time course, indicating that the repression of this subset of genes occurs as a primary response to TCDD exposure and not as a secondary response to 13 weeks of subchronic treatment. In addition, the gender, species, and AhR dependence of these responses were also investigated. Gender- and species-dependent repression was observed within this subset of genes. Furthermore, utilizing AhR knockout mice, we were able to determine the AhR-dependent downregulation of seven of 11 genes. Together these results assist efforts to understand the multitude of effects imposed by TCDD and AhR ligands on gene expression. 相似文献
10.