全文获取类型
收费全文 | 43137篇 |
免费 | 3290篇 |
国内免费 | 181篇 |
专业分类
耳鼻咽喉 | 342篇 |
儿科学 | 1401篇 |
妇产科学 | 834篇 |
基础医学 | 5566篇 |
口腔科学 | 782篇 |
临床医学 | 4227篇 |
内科学 | 9342篇 |
皮肤病学 | 615篇 |
神经病学 | 4391篇 |
特种医学 | 1372篇 |
外国民族医学 | 1篇 |
外科学 | 6287篇 |
综合类 | 646篇 |
一般理论 | 34篇 |
预防医学 | 3731篇 |
眼科学 | 832篇 |
药学 | 2994篇 |
1篇 | |
中国医学 | 61篇 |
肿瘤学 | 3149篇 |
出版年
2023年 | 241篇 |
2022年 | 321篇 |
2021年 | 806篇 |
2020年 | 536篇 |
2019年 | 812篇 |
2018年 | 918篇 |
2017年 | 714篇 |
2016年 | 749篇 |
2015年 | 915篇 |
2014年 | 1291篇 |
2013年 | 1825篇 |
2012年 | 2692篇 |
2011年 | 3013篇 |
2010年 | 1651篇 |
2009年 | 1528篇 |
2008年 | 2531篇 |
2007年 | 2826篇 |
2006年 | 2707篇 |
2005年 | 2789篇 |
2004年 | 2579篇 |
2003年 | 2427篇 |
2002年 | 2260篇 |
2001年 | 535篇 |
2000年 | 474篇 |
1999年 | 577篇 |
1998年 | 529篇 |
1997年 | 407篇 |
1996年 | 390篇 |
1995年 | 344篇 |
1994年 | 306篇 |
1993年 | 327篇 |
1992年 | 392篇 |
1991年 | 373篇 |
1990年 | 299篇 |
1989年 | 284篇 |
1988年 | 322篇 |
1987年 | 284篇 |
1986年 | 261篇 |
1985年 | 298篇 |
1984年 | 316篇 |
1983年 | 297篇 |
1982年 | 304篇 |
1981年 | 292篇 |
1980年 | 298篇 |
1979年 | 185篇 |
1978年 | 195篇 |
1977年 | 176篇 |
1976年 | 163篇 |
1974年 | 151篇 |
1973年 | 143篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
91.
92.
93.
94.
95.
Paul J Limburg Rachael Z Stolzenberg-Solomon Robert A Vierkant Katherine Roberts Thomas A Sellers Philip R Taylor Jarmo Virtamo James R Cerhan Demetrius Albanes 《Clinical gastroenterology and hepatology》2006,4(12):1514-1521
BACKGROUND & AIMS: Hyperinsulinemia is a putative colorectal cancer (CRC) risk factor. Insulin resistance (IR) commonly precedes hyperinsulinemia and can be quantitatively measured by using the homeostasis model assessment-insulin resistance (HOMA-IR) index. To date, few studies have directly examined serum insulin as an indicator of CRC risk, and none have reported associations on the basis of HOMA-IR. METHODS: We performed a case-cohort study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study (n=29,133). Baseline exposure and fasting serum biomarker data were available for 134 incident CRC case and 399 non-case subjects. HOMA-IR was derived as fasting insulin x fasting glucose/22.5. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by using age-adjusted and multivariable-adjusted Cox proportional hazards regression models. RESULTS: Median (interquartile range) values for serum insulin, glucose, and HOMA-IR were 4.1 (2.9-7.2) mIU/L, 101 (94-108) mg/dL, and 0.99 (0.69-1.98) for case subjects and 4.1 (2.7-6.1) mIU/L, 99 (93-107) mg/dL, and 1.02 (0.69-1.53) for non-case subjects, respectively. On the basis of comparison of the highest versus lowest quartiles for each biomarker, insulin (HR, 1.84; 95% CI, 1.03-3.30) and HOMA-IR (HR, 1.85; 95% CI, 1.06-3.24) were significantly associated with incident CRC, whereas glucose was marginally associated with incident CRC (HR, 1.70; 95% CI, 0.92-3.13) in age-adjusted risk models. However, trends across biomarker quartiles were somewhat inconsistent (P trend=.12, .04, and .12, respectively), and multivariable adjustment generally attenuated the observed risk estimates. CONCLUSIONS: Data from this prospective study of male smokers provide limited support for hyperinsulinemia, hyperglycemia, and/or insulin resistance as CRC risk factors. 相似文献
96.
97.
Mycoplasma pneumatoceles. 总被引:1,自引:0,他引:1
98.
Routine maternal serum alpha-fetoprotein (MSAFP) screening for neural tube defects is considered by many to be standard obstetrical care, and recently many have encouraged this test to screen for Trisomy-21 (Down's syndrome). We questioned whether, after a normal MSAFP screen, the risk of Trisomy-21 decreases enough to warrant modifying the recommended age for genetic amniocentesis for Down's syndrome. A logistic regression was developed which, using reported values for sensitivity and specificity for MSAFP detection of Trisomy-21 and assuming a constant threshold risk in opting for amniocentesis, indicates that genetic amniocentesis for Trisomy-21 may be deferred in some women who have a normal MSAFP screening. Sensitivity analysis of varying thresholds for a normal MSAFP demonstrates that a 37 year old woman with a median MSAFP level has the same risk for Trisomy-21 as an unscreened women who is 4.5 years younger. An abnormal MSAFP is useful in screening for neural tube defects and possibly for Trisomy-21. A normal MSAFP may allow for delaying the potentially risky amniocentesis in otherwise low-risk pregnancies. 相似文献
99.
100.
Mallampati classification and laryngeal mask airway insertion 总被引:3,自引:0,他引:3