全文获取类型
收费全文 | 28370篇 |
免费 | 2699篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 240篇 |
儿科学 | 1003篇 |
妇产科学 | 614篇 |
基础医学 | 3601篇 |
口腔科学 | 659篇 |
临床医学 | 3264篇 |
内科学 | 5932篇 |
皮肤病学 | 226篇 |
神经病学 | 2671篇 |
特种医学 | 939篇 |
外科学 | 3894篇 |
综合类 | 496篇 |
一般理论 | 28篇 |
预防医学 | 3225篇 |
眼科学 | 507篇 |
药学 | 1943篇 |
中国医学 | 28篇 |
肿瘤学 | 1850篇 |
出版年
2022年 | 186篇 |
2021年 | 450篇 |
2020年 | 270篇 |
2019年 | 498篇 |
2018年 | 510篇 |
2017年 | 342篇 |
2016年 | 403篇 |
2015年 | 431篇 |
2014年 | 726篇 |
2013年 | 1093篇 |
2012年 | 1472篇 |
2011年 | 1521篇 |
2010年 | 844篇 |
2009年 | 743篇 |
2008年 | 1409篇 |
2007年 | 1501篇 |
2006年 | 1352篇 |
2005年 | 1385篇 |
2004年 | 1364篇 |
2003年 | 1316篇 |
2002年 | 1306篇 |
2001年 | 723篇 |
2000年 | 725篇 |
1999年 | 656篇 |
1998年 | 342篇 |
1997年 | 295篇 |
1996年 | 302篇 |
1995年 | 293篇 |
1994年 | 281篇 |
1993年 | 260篇 |
1992年 | 550篇 |
1991年 | 489篇 |
1990年 | 505篇 |
1989年 | 492篇 |
1988年 | 425篇 |
1987年 | 433篇 |
1986年 | 430篇 |
1985年 | 401篇 |
1984年 | 343篇 |
1983年 | 325篇 |
1982年 | 246篇 |
1981年 | 257篇 |
1980年 | 204篇 |
1979年 | 285篇 |
1978年 | 254篇 |
1977年 | 164篇 |
1976年 | 167篇 |
1974年 | 176篇 |
1973年 | 172篇 |
1972年 | 165篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
Michael Lefevre Author Vitae Penny M. Kris-EthertonAuthor Vitae Guixiang ZhaoAuthor Vitae Russell P. TracyAuthor Vitae 《Journal of the American Dietetic Association》2004,104(3):410-419
The cause of many myocardial infarctions is occlusive thrombosis, or a blood clot that stops blood flow in a coronary artery. Hemostasis involves a complex system of factors, which normally form and degrade blood clots, that work within a delicate balance. Emerging evidence suggests that some hemostatic factors, including factor VII, fibrinogen, and plasminogen activator inhibitor-1, are associated with increased risk for cardiovascular disease (CVD). Accumulating evidence suggests a relationship between dietary fatty acids and emerging hemostatic CVD risk factors, although much of this evidence is incomplete or conflicting. Dietary supplementation with marine n-3 fatty acids prolongs bleeding time and may decrease risk for thrombosis. Factor VII coagulant activity modestly decreases with reductions in saturated fatty acid (SFA) intake and thereby may contribute to the beneficial effects of low SFA diets. Large triglyceride-rich particles formed during postprandial lipemia can support the assembly and function of coagulation complexes and seem to play a role in the activation of factor VII, and thus may partially explain increased CVD risk associated with increased postprandial triglyceridemia. As our understanding of the role of dietary fatty acids and hemostasis evolves, it is likely that we will be able to make specific dietary recommendations to further decrease CVD risk. At this juncture, however, increasing marine n-3 fatty acids and decreasing certain SFAs are leading strategies to reduce hemostatic CVD risk factors. An array of dietary strategies that target multiple CVD risk factors could have a greater impact on CVD than a single risk factor intervention strategy. 相似文献
33.
34.
We have determined the frequency of heterozygosity of the short arm of chromosome 17 in 20 cervical tumours using the highly polymorphic probe pYNZ22. Only 25% of the tumours were heterozygous at this locus. This is significantly lower than the level of 86% heterozygosity for this locus in the general population indicating that loss of one allele occurs in cervical cancer. Heterozygosity for a locus on the long arm of the same chromosome showed no significant difference between the tumours and the general population indicating that genetic loss was confined to the short arm of the chromosome. The analysis of premalignant lesions showed 70% of patients were heterozygous suggesting that loss of material from the short arm of chromosome 17 took place at a late stage in tumour development. This report confirms predictions made from previous karyotypic analysis and is the first indication of allele loss on the short arm of chromosome 17 in cervical cancer. 相似文献
35.
F M Muggia E LePoidevin S Jeffers C Russell W Boswell C P Morrow J Curtin J Schlaerth 《Annals of oncology》1992,3(2):149-154
Nineteen patients with ovarian cancer and minimal residual or persistent disease who were treated with cisplatin or carboplatin-based intraperitoneal (IP) regimens had distribution studies of IP contrast and computerized tomography prior to and during treatment. The distribution pattern was assessed retrospectively and scored for the presence of contrast in each of eight regions: the under surface of right and left diaphragms, the right and left paracolic gutters, the lesser omental sac, the intramesenteric region and the true and false pelvis. Assigning a point to each region with adequate distribution, we classified 10 patients to an excellent pattern (greater than or equal to 7 of 8 regions), 6 to a good pattern (5 to less than 7 regions), and 3 to an inadequate distribution pattern (less than 5 regions). Serial studies were performed in 8 patients after more than 4 cycles of IP therapy. In these patients, all of whom were tolerating treatment without progression, the distribution remained virtually unchanged for those with excellent distribution. One of three with good distribution manifested inadequate distribution on repeat study, and one of two with inadequate distribution improved to show a good pattern. In this small study there was no correlation of distribution patterns with plasma CA-125 at onset of IP treatment and prior surgical procedures or placement of the catheter tip. However, three patients with unsatisfactory patterns had procedures consisting of catheter placement only rather than formal reassessment laparotomies for ovarian cancer. Since satisfactory IP distribution may be required for obtaining a therapeutic advantage from IP therapy, methods for its assessment must be developed.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
36.
Sheana Salyers Bull Cynthia Gillette Russell E Glasgow Paul Estabrooks 《Health education & behavior》2003,30(5):537-549
Information on external validity of work site health promotion research is essential to translate research findings to practice. The authors provide a literature review of work site health behavior interventions. Using the RE-AIM framework, they summarize characteristics and results of these studies to document reporting of intervention reach, adoption, implementation, and maintenance. The authors reviewed a total of 24 publications from 11 leading health behavior journals. They found that participation rates among eligible employees were reported in 87.5% of studies; only 25% of studies reported on intervention adoption. Data on characteristics of participants versus nonparticipants were reported in fewer than 10% of studies. Implementation data were reported in 12.5% of the studies. Only 8% of studies reported any type of maintenance data. Stronger emphasis is needed on representativeness of employees, work site settings studied, and longer term results. Examples of how this can be done are provided. 相似文献
37.
Nonsteroidal anti-inflammatory drug use and increased risk for peptic ulcer disease in elderly persons 总被引:25,自引:0,他引:25
M R Griffin J M Piper J R Daugherty M Snowden W A Ray 《Annals of internal medicine》1991,114(4):257-263
OBJECTIVE: To evaluate the relative risk for peptic ulcer disease that is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. DESIGN: Nested case-control study. SETTING: Tennessee Medicaid program. PARTICIPANTS: Medicaid enrollees 65 years of age or older were included in the study. The 1415 case patients had been hospitalized for confirmed peptic ulcer disease at some point from 1984 through 1986. The 7063 control persons represented a stratified random sample of other Medicaid enrollees. MEASUREMENTS AND MAIN RESULTS: The estimated relative risk for the development of peptic ulcer disease among current users of nonaspirin nonsteroidal anti-inflammatory drugs, compared with that among nonusers, was 4.1 (95% CI, 3.5 to 4.7). For current users, the risk increased with increasing dose, from a relative risk of 2.8 (CI, 1.8 to 4.3) for the lowest to a relative risk of 8.0 (CI, 4.4 to 14.8) for the highest dose category. The risk was greatest in the first month of use (relative risk, 7.2; CI, 4.9 to 10.5). If the association is fully causal, 29% of peptic ulcers in the study sample resulted from the use of these drugs, and the excess risk associated with such use was 17.4 hospitalizations for ulcer disease per 1000 person-years of exposure. CONCLUSIONS: These data support other findings indicating that a clinically significant risk for serious ulcer disease is associated with the use of nonaspirin nonsteroidal anti-inflammatory drugs. The data show that this risk increases with dose and recency of use and that use of these drugs may be responsible for a large proportion of peptic ulcer disease among elderly persons. 相似文献
38.
39.
Factors affecting conjugative transfer of plasmid pWG613, determining gentamicin resistance, in Staphylococcus aureus 总被引:2,自引:0,他引:2
Factors that are known to influence plasmid transfer in bacterial populations were studied for the conjugative plasmid pWG613, which determined gentamicin resistance in Staphylococcus aureus. The transfer frequency was largely unaffected over a wide range of temperature (18-42 degrees C); pH also had little effect on the transfer frequency in the range 5.0-8.5. High cell density and log phase cultures were required for optimal plasmid transfer, as were donor:recipient ratios of 0.003-3.3. 相似文献
40.
Complications associated with maxillary nerve block anaesthesia via the greater palatine canal 总被引:2,自引:0,他引:2
Anthony M. Sved John D. Wong Head Peter Donkor James Horan Leesa Rix Justin Curtin and Russell Vickers 《Australian dental journal》1992,37(5):340-345
This paper documents the type, frequency and duration of complications associated with regional anaesthesia of the maxillary nerve via the greater palatine canal in a series of 101 patients treated in the Oral Surgery Department, United Dental Hospital of Sydney. 相似文献