全文获取类型
收费全文 | 1036565篇 |
免费 | 77171篇 |
国内免费 | 10680篇 |
专业分类
耳鼻咽喉 | 13551篇 |
儿科学 | 30449篇 |
妇产科学 | 27668篇 |
基础医学 | 146936篇 |
口腔科学 | 27134篇 |
临床医学 | 91550篇 |
内科学 | 202061篇 |
皮肤病学 | 20508篇 |
神经病学 | 78062篇 |
特种医学 | 41240篇 |
外国民族医学 | 401篇 |
外科学 | 155388篇 |
综合类 | 42271篇 |
现状与发展 | 29篇 |
一般理论 | 259篇 |
预防医学 | 74119篇 |
眼科学 | 23483篇 |
药学 | 79710篇 |
120篇 | |
中国医学 | 9581篇 |
肿瘤学 | 59896篇 |
出版年
2021年 | 12985篇 |
2020年 | 8895篇 |
2019年 | 11018篇 |
2018年 | 13876篇 |
2017年 | 11619篇 |
2016年 | 11912篇 |
2015年 | 14934篇 |
2014年 | 20047篇 |
2013年 | 26657篇 |
2012年 | 36082篇 |
2011年 | 38334篇 |
2010年 | 24374篇 |
2009年 | 22073篇 |
2008年 | 33640篇 |
2007年 | 35283篇 |
2006年 | 34736篇 |
2005年 | 33672篇 |
2004年 | 31137篇 |
2003年 | 30185篇 |
2002年 | 29057篇 |
2001年 | 44600篇 |
2000年 | 45309篇 |
1999年 | 38720篇 |
1998年 | 11554篇 |
1997年 | 10885篇 |
1996年 | 10290篇 |
1995年 | 9592篇 |
1994年 | 9121篇 |
1993年 | 8288篇 |
1992年 | 29090篇 |
1991年 | 27767篇 |
1990年 | 27118篇 |
1989年 | 26000篇 |
1988年 | 24144篇 |
1987年 | 23659篇 |
1986年 | 22727篇 |
1985年 | 21543篇 |
1984年 | 16134篇 |
1983年 | 13739篇 |
1982年 | 8327篇 |
1979年 | 14759篇 |
1978年 | 10379篇 |
1977年 | 8817篇 |
1976年 | 8314篇 |
1975年 | 9060篇 |
1974年 | 10831篇 |
1973年 | 10289篇 |
1972年 | 9756篇 |
1971年 | 9027篇 |
1970年 | 8683篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
152.
Yuan Peng Yuman Li Haiyan Cao Liu Hong Yu Wang Mingxing Xie 《Journal of ultrasound in medicine》2019,38(2):539-544
A pulmonary artery (PA) sling is a very rare congenital cardiovascular anomaly, and only a few studies have reported PA slings in fetuses. The relationship of the PA, aorta, ductus arteriosus, and trachea can be evaluated in the 3‐vessel and 3‐vessel and trachea views during fetal echocardiography. A PA sling can be detected by abnormal positioning of the left PA in relation to the trachea when sweeping from the 3‐vessel view cranially to the 3‐vessel and trachea view. Here we report 3 cases of fetal PA slings and their follow‐ups. Two cases were confirmed by postnatal echocardiography, and the other case was confirmed by a cardiovascular cast after pregnancy termination. We emphasize that the 3‐vessel and 3‐vessel and trachea views are of crucial importance in the prenatal diagnosis of a PA sling. 相似文献
153.
154.
155.
Chien-Hua Tseng Ben-Jei Tsuang Chun-Ju Chiang Kai-Chen Ku Jeng-Sen Tseng Tsung-Ying Yang Kuo-Hsuan Hsu Kun-Chieh Chen Sung-Liang Yu Wen-Chung Lee Tsang-Wu Liu Chang-Chuan Chan Gee-Chen Chang 《Journal of thoracic oncology》2019,14(5):784-792
Introduction
For never-smokers (smoked <100 lifetime cigarettes), lung cancer (LC) has emerged as an important issue. We aimed to investigate the effects of prevalence changes in tobacco smoking and particulate matter (PM) 2.5 (PM2.5) levels on LC in Taiwan, in relation to contrasting PM2.5 levels, between Northern Taiwan (NT) and Southern Taiwan (ST).Methods
We reviewed 371,084 patients with LC to assess smoking prevalence and correlations between the incidence of adenocarcinoma lung cancer (AdLC) and non-AdLC. Two subsets were selected to assess different AdLC stage trends and the effect of PM2.5 on survival of patients with AdLC.Results
From 1995 to 2015, the proportion of male adult ever-smokers decreased from 59.4% to 29.9% whereas the female smoking rate remained low (3.2% to 5.3%). AdLC incidence in males and females increased from 9.06 to 23.25 and 7.05 to 24.22 per 100,000 population, respectively. Since 1993, atmospheric visibility in NT improved (from 7.6 to 11.5 km), but deteriorated in ST (from 16.3 to 4.2 km). The annual percent change in AdLC stages IB to IV was 0.3% since 2009 (95% confidence interval [CI]: -1.9%–2.6%) in NT, and 4.6% since 2007 (95% CI: 3.3%–5.8%) in ST; 53% patients with LC had never smoked. Five-year survival rates for never-smokers, those with EGFR wild-type genes, and female patients with AdLC were 12.6% in NT and 4.5% in ST (hazard ratio: 0.79, 95% CI: 0.70–0.90).Conclusions
In Taiwan, greater than 50% of patients with LC had never smoked. PM2.5 level changes can affect AdLC incidence and patient survival. 相似文献156.
157.
158.
159.
Sandrine F. Chebekoue 《Journal of occupational and environmental hygiene》2019,16(4):308-319
This study aimed at deriving occupational thresholds of toxicological concern for inhalation exposure to systemically-acting organic chemicals using predicted internal doses. The latter were also used to evaluate the quantitative relationship between occupational exposure limit and internal dose. Three internal dose measures were identified for investigation: (i) the daily area under the venous blood concentration vs. time curve, (ii) the daily rate of the amount of parent chemical metabolized, and (iii) the maximum venous blood concentration at the end of an 8-hr work shift. A dataset of 276 organic chemicals with 8-hr threshold limit values-time-weighted average was compiled along with their molecular structure and Cramer classes (Class I: low toxicity, Class II: intermediate toxicity, Class III: suggestive of significant toxicity). Using a human physiologically-based pharmacokinetic model, the three identified dose metrics were predicted for an 8-hr occupational inhalation exposure to the threshold limit value for each chemical. Distributional analyses of the predicted dose metrics were performed to identify the percentile values corresponding to the occupational thresholds of toxicological concern. Also, simple linear regression analyses were performed to evaluate the relationship between the 8-hr threshold limit value and each of the predicted dose metrics, respectively. No threshold of toxicological concern could be derived for class II due to few chemicals. Based on the daily rate of the amount of parent chemical metabolized, the proposed internal dose-based occupational thresholds of toxicological concern were 5.61?×?10?2 and 9?×?10?4 mmol/d at the 10th percentile level for classes I and III, respectively, while they were 4.55?×?10?1 and 8.5?×?10?3 mmol/d at the 25th percentile level. Even though high and significant correlations were observed between the 8-hr threshold limit values and the predicted dose metrics, the one with the rate of the amount of chemical metabolized was remarkable regardless of the Cramer class (r2 = 0.81; n = 276). The proposed internal dose-based occupational thresholds of toxicological concern are potentially useful for screening-level assessments as well as prioritization within an integrated occupational risk assessment framework. 相似文献
160.