全文获取类型
收费全文 | 8583篇 |
免费 | 806篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 120篇 |
儿科学 | 271篇 |
妇产科学 | 427篇 |
基础医学 | 1360篇 |
口腔科学 | 167篇 |
临床医学 | 1105篇 |
内科学 | 1469篇 |
皮肤病学 | 146篇 |
神经病学 | 701篇 |
特种医学 | 667篇 |
外国民族医学 | 1篇 |
外科学 | 798篇 |
综合类 | 267篇 |
一般理论 | 11篇 |
预防医学 | 793篇 |
眼科学 | 160篇 |
药学 | 508篇 |
中国医学 | 6篇 |
肿瘤学 | 530篇 |
出版年
2021年 | 95篇 |
2020年 | 84篇 |
2019年 | 101篇 |
2018年 | 129篇 |
2017年 | 70篇 |
2016年 | 138篇 |
2015年 | 110篇 |
2014年 | 156篇 |
2013年 | 254篇 |
2012年 | 327篇 |
2011年 | 400篇 |
2010年 | 229篇 |
2009年 | 214篇 |
2008年 | 342篇 |
2007年 | 344篇 |
2006年 | 330篇 |
2005年 | 362篇 |
2004年 | 333篇 |
2003年 | 288篇 |
2002年 | 283篇 |
2001年 | 278篇 |
2000年 | 295篇 |
1999年 | 244篇 |
1998年 | 184篇 |
1997年 | 167篇 |
1996年 | 179篇 |
1995年 | 160篇 |
1994年 | 156篇 |
1993年 | 141篇 |
1992年 | 199篇 |
1991年 | 189篇 |
1990年 | 209篇 |
1989年 | 226篇 |
1988年 | 201篇 |
1987年 | 192篇 |
1986年 | 150篇 |
1985年 | 155篇 |
1984年 | 135篇 |
1983年 | 95篇 |
1982年 | 86篇 |
1981年 | 72篇 |
1980年 | 93篇 |
1979年 | 124篇 |
1978年 | 99篇 |
1977年 | 78篇 |
1976年 | 93篇 |
1975年 | 71篇 |
1974年 | 81篇 |
1973年 | 59篇 |
1972年 | 67篇 |
排序方式: 共有9507条查询结果,搜索用时 31 毫秒
91.
OBJECTIVES: To investigate the obstetric antecedents for preterm delivery (PTD) in an Irish urban obstetric population, and to evaluate the incidence and outcome of such deliveries. STUDY DESIGN: A retrospective observational study of all preterm deliveries at the Rotunda Hospital, Dublin during the six-year period 1997-2002. The findings for early preterm deliveries (EPTD) (24+0-31+6 weeks' gestation), and late preterm deliveries (LPTD) (32+0-36+6 weeks' gestation) were analyzed separately. RESULTS: There were 38,795 deliveries after 24 weeks' gestation or >500 g birth weight, of which 2839 (7.3%) were preterm. Of all preterm deliveries, 626 (22.1%) were EPTD and 2213 (77.9%) were LPTD, resulting in an EPTD rate of 1.6% and an LPTD rate of 5.7%. Spontaneous unexplained preterm delivery accounted for 1221 (43.0%) of preterm deliveries (PTD), and of these 213 (34%) cases were EPTD and 1008 (45.5%) LPTD. The other most frequently observed obstetric causative factors, in order of importance, were multiple gestation (676; 23.8% of PTD), hypertensive disorders of pregnancy (243; 8.6%), antepartum hemorrhage (194; 6.8%), stillbirth (105; 3.7%), intrauterine growth restriction (53; 1.9%) and preterm prelabor rupture of membranes+/-chorioamnionitis (32; 1.1%). There were 75 early neonatal deaths among infants born prematurely, plus 105 stillbirths, resulting in a perinatal mortality rate of 63 per 1000 for PTD (n=180), which on subsequent analysis was 158 per 1000 for EPTD (n=99) and 37 per 1000 for LPTD (n=81). CONCLUSIONS: These data outline the obstetric factors linked to preterm delivery within a recent Irish urban obstetric population. Spontaneous idiopathic preterm labor was the principle causative factor in 43% of all preterm deliveries, and represents the proportion of women for whom future therapeutic intervention may be of benefit. 相似文献
92.
93.
94.
95.
96.
The American Journal of Digestive Diseases - The physiologic mechanism of thyroid action upon the gastro-intestinal tract has not been clearly established in the past. A preliminary study was made... 相似文献
98.
Amy C. Morrison Robert C. Reiner Jr. William H. Elson Helvio Astete Carolina Guevara Clara del Aguila Isabel Bazan Crystyan Siles Patricia Barrera Anna B. Kawiecki Christopher M. Barker Gissella M. Vasquez Karin Escobedo-Vargas Carmen Flores-Mendoza Alfredo A. Huaman Mariana Leguia Maria E. Silva Sarah A. Jenkins Wesley R. Campbell Eugenio J. Abente Robert D. Hontz Valerie A. Paz-Soldan John P. Grieco Neil F. Lobo Thomas W. Scott Nicole L. Achee 《Proceedings of the National Academy of Sciences of the United States of America》2022,119(26)
Over half the world’s population is at risk for viruses transmitted by Aedes mosquitoes, such as dengue and Zika. The primary vector, Aedes aegypti, thrives in urban environments. Despite decades of effort, cases and geographic range of Aedes-borne viruses (ABVs) continue to expand. Rigorously proven vector control interventions that measure protective efficacy against ABV diseases are limited to Wolbachia in a single trial in Indonesia and do not include any chemical intervention. Spatial repellents, a new option for efficient deployment, are designed to decrease human exposure to ABVs by releasing active ingredients into the air that disrupt mosquito–human contact. A parallel, cluster-randomized controlled trial was conducted in Iquitos, Peru, to quantify the impact of a transfluthrin-based spatial repellent on human ABV infection. From 2,907 households across 26 clusters (13 per arm), 1,578 participants were assessed for seroconversion (primary endpoint) by survival analysis. Incidence of acute disease was calculated among 16,683 participants (secondary endpoint). Adult mosquito collections were conducted to compare Ae. aegypti abundance, blood-fed rate, and parity status through mixed-effect difference-in-difference analyses. The spatial repellent significantly reduced ABV infection by 34.1% (one-sided 95% CI lower limit, 6.9%; one-sided P value = 0.0236, z = 1.98). Aedes aegypti abundance and blood-fed rates were significantly reduced by 28.6 (95% CI 24.1%, ∞); z = −9.11) and 12.4% (95% CI 4.2%, ∞); z = −2.43), respectively. Our trial provides conclusive statistical evidence from an appropriately powered, preplanned cluster-randomized controlled clinical trial of the impact of a chemical intervention, in this case a spatial repellent, to reduce the risk of ABV transmission compared to a placebo.Aedes-borne viral diseases (ABVDs) [e.g., dengue (DENV), chikungunya, Zika (ZIKV), and yellow fever] are devastating, expanding global public health threats that disproportionally affect low- and middle-income countries. DENV, one of the most rapidly increasing vector-borne infectious diseases, results in ∼400 million infections each year (1, 2), with 4 billion people at risk for infection annually (3). Currently, the primary means for ABVD prevention is controlling the primary mosquito vector, Aedes aegypti. Existing vector control interventions, however, have failed to prevent ABV transmission and epidemics (4–6).There is an urgent need to develop evidence-based guidance for the use of new and existing ABV vector control tools. The evidence base for vector control against ABVs is weak, despite considerable government investments in World Health Organization (WHO)-recommended control of larval habitats (larviciding, container removal) and ultra-low-volume insecticide spraying (4, 5, 7–9). These strategies continue to be implemented despite the lack of rigorously generated data from controlled clinical trials demonstrating they reduce ABV infection or disease (6). The only ABV intervention with a proven epidemiological impact in a cluster-randomized control trial (cRCT) assessed community mobilization to reduce mosquito larval habitats (10). A recent test-negative trial with Wolbachia-infected mosquitoes reported a significant reduction of DENV illness in Indonesia (11).Spatial repellents (SRs) are devices that contain volatile active ingredients that disperse in air. The active ingredients can repel mosquitoes from entering a treated space, inhibit attraction to human host cues, or disrupt mosquito biting and blood-feeding behavior and, thus, interfere with mosquito–human contact (12–14). Any of these outcomes reduce the probability of pathogen transmission. Pyrethroid-based SRs have shown efficacy in reducing malaria infections in China (15) and Indonesia (16). There have, however, been no clinical trials evaluating the protective efficacy (PE) of SRs against ABV infection or disease.To generate evidence for public health consideration, we conducted a double-blinded, parallel cRCT to demonstrate and quantify the PE of a transfluthrin-based SR to reduce ABV infection incidence over 2 y in a human cohort in Iquitos, Peru. 相似文献
99.
James K. Morrison 《Journal of clinical psychology》1977,33(2):549-551
As compared with a group of matched controls, psychiatric clients exposed to demythologizing seminars made significant and positive changes in the qualities that they attributed to the mental patient. Implications of this study for further research were discussed. 相似文献
100.
液基细胞学结合阴道镜检查在北京市社区妇女宫颈病变筛查中的意义 总被引:2,自引:0,他引:2
目的探讨宫颈液基细胞学及阴道镜检查在北京市社区妇女宫颈病变筛查中的临床意义。方法2006年6月至2007年6月对北京市展览路社区的795位20~54岁有性生活的妇女进行筛查。筛查对象接受妇科检查时,留取宫颈超柏氏薄层液基细胞学检测标本,并对宫颈细胞学异常者行阴道镜检查及活组织检查。结果宫颈细胞学阳性[≥ASC-US(不能明确意义的不典型鳞状细胞)]45例,占5.7%(45/795)。其中ASC-US33例,占73.3%(33/45);低度鳞状上皮内病变8例;高度鳞状上皮内病变3例;不典型腺细胞1例。细胞学阴性750例,占94.3%(750/795)。宫颈细胞学阳性的45例中,5例拒绝行阴道镜检查,占11.1%(5/45)。在行阴道镜活组织病理检查的40例中,慢性宫颈炎11例(27.5%);宫颈湿疣14例(35.0%);宫颈上皮内瘤样病变(CIN)1为7例(17.5%);CIN2为3例(7.5%);CIN3为4例(10.0%);早期浸润癌1例(2.5%)。细胞学阴性的750例中,宫颈湿疣2例(0.3%);CIN1为5例(0.7%);宫颈低级别腺上皮内病变1例(0.1%)。宫颈液基细胞学筛查CIN1及以上宫颈病变和宫颈癌的敏感度71.4%,特异度94.2%,阳性预测值37.5%,阴性预测值99.2%;筛查CIN2及以上宫颈病变和宫颈癌的敏感度100.0%,特异度96.0%,阳性预测值20.5%,阴性预测值100.0%。结论应重视并及时进行北京市社区人群宫颈病变的早期筛查,薄层液基细胞学结合阴道镜活组织检查及病理学检查,对提高早期宫颈癌筛查的准确性效果明显。 相似文献