全文获取类型
收费全文 | 7907篇 |
免费 | 649篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 296篇 |
妇产科学 | 140篇 |
基础医学 | 1340篇 |
口腔科学 | 117篇 |
临床医学 | 929篇 |
内科学 | 1447篇 |
皮肤病学 | 149篇 |
神经病学 | 928篇 |
特种医学 | 161篇 |
外科学 | 790篇 |
综合类 | 42篇 |
一般理论 | 7篇 |
预防医学 | 951篇 |
眼科学 | 136篇 |
药学 | 557篇 |
中国医学 | 22篇 |
肿瘤学 | 490篇 |
出版年
2024年 | 19篇 |
2023年 | 121篇 |
2022年 | 218篇 |
2021年 | 403篇 |
2020年 | 235篇 |
2019年 | 394篇 |
2018年 | 387篇 |
2017年 | 284篇 |
2016年 | 291篇 |
2015年 | 311篇 |
2014年 | 399篇 |
2013年 | 450篇 |
2012年 | 710篇 |
2011年 | 734篇 |
2010年 | 341篇 |
2009年 | 328篇 |
2008年 | 480篇 |
2007年 | 446篇 |
2006年 | 424篇 |
2005年 | 355篇 |
2004年 | 336篇 |
2003年 | 288篇 |
2002年 | 272篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 30篇 |
1998年 | 41篇 |
1997年 | 32篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 8篇 |
1993年 | 23篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 4篇 |
1977年 | 6篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有8577条查询结果,搜索用时 15 毫秒
971.
972.
Morris DH Jones ME Schoemaker MJ McFadden E Ashworth A Swerdlow AJ 《American journal of epidemiology》2012,175(10):998-1005
The authors examined the effect of women's lifestyles on the timing of natural menopause using data from a cross-sectional questionnaire used in the United Kingdom-based Breakthrough Generations Study in 2003-2011. The analyses included 50,678 women (21,511 who had experienced a natural menopause) who were 40-98 years of age at study entry and did not have a history of breast cancer. Cox competing risks proportional hazards models were fitted to examine the relation of age at natural menopause to lifestyle and anthropometric factors. Results were adjusted for age at reporting, smoking status at menopause, parity, and body mass index at age 40 years, as appropriate. All P values were 2-sided. High adult weight (P(trend) < 0.001), high body mass index (P(trend) < 0.001), weight gain between the ages of 20 and 40 years (P(trend) = 0.01), not smoking (P < 0.001), increased alcohol consumption (P(trend) < 0.001), regular strenuous exercise (P < 0.01), and not being a vegetarian (P < 0.001) were associated with older age at menopause. Neither height nor history of an eating disorder was associated with menopausal age. These findings show the importance of lifestyle factors in determining menopausal age. 相似文献
973.
974.
975.
976.
Process optimization and scale-up for production of rabies vaccine live adenovirus vector (AdRG1.3) 总被引:1,自引:0,他引:1
Rabies virus is an important causative agent of disease resulting in an acute infection of the nervous system and death. Although curable if treated in a timely manner, rabies remains a serious public health issue in developing countries, and the indigenous threat of rabies continues in developed countries because of wildlife reservoirs. Control of rabies in wildlife is still an important challenge for governmental authorities.There are a number of rabies vaccines commercially available for control of wildlife rabies infection. However, the vaccines currently distributed to wildlife do not effectively immunize all at-risk species, particularly skunks. A replication competent recombinant adenovirus expressing rabies glycoprotein (AdRG1.3) has shown the most promising results in laboratory trials. The adenovirus vectored vaccine is manufactured using HEK 293 cells.This study describes the successful scale-up of AdRG1.3 adenovirus production from 1 to 500 L and the manufacturing of large quantities of bulk material required for field trials to demonstrate efficacy of this new candidate vaccine. The production process was streamlined by eliminating a medium replacement step prior to infection and the culture titer was increased by over 2 fold through optimization of cell culture medium. These improvements produced a more robust and cost-effective process that facilitates industrialization and commercialization. Over 17,000 L of AdRG1.3 adenovirus cultures were manufactured to support extensive field trials. AdRG1.3 adenovirus is formulated and packaged into baits by Artemis Technologies Inc. using proprietary technology. Field trials of AdRG1.3 rabies vaccine baits have been conducted in several Canadian provinces including Ontario, Quebec and New Brunswick. The results from field trials over the period 2006-2009 demonstrated superiority of the new vaccine over other licensed vaccines in immunizing wild animals that were previously difficult to vaccinate. 相似文献
977.
978.
Anderson PD Johnson AC Pfeiffer D Caldwell DJ Hannah R Mastrocco F Sumpter JP Williams RJ 《Environmental toxicology and chemistry / SETAC》2012,31(6):1407-1415
In an effort to assess the combined risk estrone (E1), 17β-estradiol (E2), 17α-ethinyl estradiol (EE2), and estriol (E3) pose to aquatic wildlife across United States watersheds, two sets of predicted-no-effect concentrations (PNECs) for significant reproductive effects in fish were compared to predicted environmental concentrations (PECs). One set of PNECs was developed for evaluation of effects following long-term exposures. A second set was derived for short-term exposures. Both sets of PNECs are expressed as a 17β-estradiol equivalent (E2-eq), with 2 and 5 ng/L being considered the most likely levels above which fish reproduction may be harmed following long-term and short-term exposures, respectively. A geographic information system-based water quality model, Pharmaceutical Assessment and Transport Evaluation (PhATE?), was used to compare these PNECs to mean and low flow concentrations of the steroid estrogens across 12 U.S. watersheds. These watersheds represent approximately 19% of the surface area of the 48 North American states, contain 40 million people, and include over 44,000 kilometers of rivers. This analysis determined that only 0.8% of the segments (less than 1.1% of kilometers) of these watersheds would have a mean flow E2-eq concentration exceeding the long-term PNEC of 2.0 ng/L; only 0.5% of the segments (less than 0.8% of kilometers) would have a critical low flow E2-eq exceeding the short-term PNEC of 5 ng/L. Those few river segments where the PNECs were exceeded were effluent dominated, being either headwater streams with a publicly owned treatment works (POTW), or flowing through a highly urbanized environment with one or several POTWs. These results suggest that aquatic species in most U.S. surface waters are not at risk from steroid estrogens that may be present as a result of human releases. 相似文献
979.
Guzman-Cottrill JA Bryant KA Zerr DM Harris AA Alexander ER Boone Z Siegel JD 《Infection control and hospital epidemiology》2012,33(3):299-301
We surveyed Ronald McDonald Houses (RMHs) to assess infection prevention and control (IPC) practices. A diverse patient population is served by RMH. Most sites have locally written IPC guidelines, and consultation resources vary, increasing the potential for inconsistent IPC practices. RMH would benefit from a standardized IPC guideline. 相似文献
980.