全文获取类型
收费全文 | 2872篇 |
免费 | 185篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 45篇 |
妇产科学 | 24篇 |
基础医学 | 292篇 |
口腔科学 | 141篇 |
临床医学 | 279篇 |
内科学 | 568篇 |
皮肤病学 | 71篇 |
神经病学 | 191篇 |
特种医学 | 71篇 |
外科学 | 532篇 |
综合类 | 26篇 |
预防医学 | 120篇 |
眼科学 | 20篇 |
药学 | 330篇 |
中国医学 | 5篇 |
肿瘤学 | 330篇 |
出版年
2023年 | 31篇 |
2022年 | 19篇 |
2021年 | 91篇 |
2020年 | 43篇 |
2019年 | 41篇 |
2018年 | 74篇 |
2017年 | 48篇 |
2016年 | 57篇 |
2015年 | 49篇 |
2014年 | 90篇 |
2013年 | 102篇 |
2012年 | 160篇 |
2011年 | 178篇 |
2010年 | 87篇 |
2009年 | 92篇 |
2008年 | 146篇 |
2007年 | 175篇 |
2006年 | 143篇 |
2005年 | 148篇 |
2004年 | 133篇 |
2003年 | 115篇 |
2002年 | 99篇 |
2001年 | 69篇 |
2000年 | 86篇 |
1999年 | 62篇 |
1998年 | 48篇 |
1997年 | 30篇 |
1996年 | 25篇 |
1995年 | 29篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 53篇 |
1991年 | 46篇 |
1990年 | 53篇 |
1989年 | 45篇 |
1988年 | 50篇 |
1987年 | 51篇 |
1986年 | 39篇 |
1985年 | 51篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1981年 | 10篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1974年 | 10篇 |
1967年 | 10篇 |
排序方式: 共有3068条查询结果,搜索用时 515 毫秒
41.
Summary The effects on atrio-ventricular (A-V) conduction and blood flow of calcium-antagonists (verapamil, nifedipine and diltiazem), local anaesthetics (procaine and lidocaine) and quinidine were investigated in the isolated, cross-circulated A-V node preparation of the dog. The drugs were injected individually into the posterior septal artery (PSA) through which the upper part of the A-V node is mainly perfused or into the anterior septal artery (ASA) through which the lower part of the node and the more distal conduction system are perfused. Single injections into the PSA of nifedipine (0.3–10 g), verapamil (1–30 g), diltiazem (1–30 g), quinidine (30–300 g), lidocaine (100 g–1 mg) and procaine (300 g–3 mg) produced a dose-related increase in the A-V conduction time and with higher doses of these drugs a second or third degree block of A-V conduction occurred. Nifedipine (0.3–30 g) and verapamil (1–100 g) injected into the ASA scarcely affected A-V conduction. Quinidine (30 g–1 mg) and lidocaine (100 g–3 mg) injected into the ASA prolonged the A-V conduction time in a dose-related manner, although the effects were less prominent than those produced upon injection into the PSA. High doses of quinidine (3 mg) and lidocaine (3–10 mg) injected into the ASA altered the shape of ventricular bipolar electrograms and prolonged the time interval between an electrogram of the right bundle branch and that of the ventricle. The results are consistent with the hypothesis that in excitation of A-V nodal cells a slow calcium current rather than a fast sodium current plays an important role and that in the His-Purkinje-ventricular system the fast sodium current is predominant. Single injections of the 6 drugs into the PSA produced a doserelated increase in blood flow through the PSA. All drugs but nifedipine increased the blood flow in almost the same dose range that caused impairment of A-V conduction. Nifedipine was 10 times more potent in increasing the blood flow than in impairing A-V conduction. 相似文献
42.
Kageyama T Kabuto M Nitta H Kurokawa Y Taira K Suzuki S Takemoto T 《Psychiatry and clinical neurosciences》2000,54(3):299-300
The prevalence of nocturia among Japanese community-dwelling adults was associated with insomnia, taking into account other correlates of insomnia. 相似文献
43.
44.
Anthony T C Chan Qian Tao Keith D Robertson Ian W Flinn Risa B Mann Barbara Klencke Wing Hong Kwan Thomas Wai-Tong Leung Philip J Johnson Richard F Ambinder 《Journal of clinical oncology》2004,22(8):1373-1381
PURPOSE: To determine whether therapy with a DNA methyltransferase inhibitor is effective in achieving demethylation and gene re-expression in tumor DNA in patients. METHODS: Biopsy specimens were obtained from patients with Epstein-Barr virus-associated tumors, enrolled on a clinical trial of 5-azacitidine, within 72 hours of the conclusion of the last infusion of the first cycle of therapy, and compared to pretreatment specimens. Methylation-specific polymerase chain reaction, bisulfite genomic sequencing, and immunohistochemistry were used to assess demethylation and gene re-expression. RESULTS: Substantial degrees of demethylation were detected in all latent and lytic Epstein-Barr virus promoters examined. Immunohistochemistry suggested activation of a previously silent viral antigen expression in one instance. CONCLUSION: Pharmacologic reversal of dense CpG methylation in tumor tissue can be achieved in patients. 相似文献
45.
46.
47.
48.
49.
Masuda H Moriyama Y Toda R Shimokawa S Iguro Y Watanabe S Hisatomi K Matsumoto H Taira A 《The Journal of thoracic and cardiovascular surgery》2000,120(4):699-706
OBJECTIVE: Human T lymphotropic virus type I infects CD4(+) T cells and affects cell-mediated immunity. Cardiopulmonary bypass transiently alters lymphocyte subsets, resulting in a reduction in CD4(+) T cells and an increase in CD8(+) T cells. We proposed that cardiovascular operations and human T lymphotropic virus type I infection may act synergistically, resulting in serious damage to cell-mediated immunity. METHODS: A total of 517 consecutive patients who were preoperatively screened for anti-human T lymphotropic virus type I antibody and underwent cardiovascular operations with cardiopulmonary bypass were enrolled in this study. Of the 517 patients, 82 (16%) had positive test results for anti-human T lymphotropic virus type I antibody. The surgical outcome of patients with positive and negative results for anti-human T lymphotropic virus type I antibody was analyzed retrospectively. RESULTS: There was no difference between the 2 groups with respect to early mortality. Distribution of survival curve was also not significantly different (P =.5; mean follow-up duration, 2.4 +/- 1.8 years [range, 0-9.4 years] and 3.2 +/- 2.8 years [range, 0-9.8 years]) in the groups with positive and negative antibody results, respectively). In particular, long-term follow-up did not reveal adult T-cell leukemia or human T lymphotropic virus type I-associated myelopathy, and occurrence of neoplasm did not differ between groups. Early infectious complication was, however, significantly higher in the group with positive antibody results than in the group with negative results (P =.02). Logistic regression analysis revealed human T lymphotropic virus type I infection as a significant risk for this complication (P =.04; odds ratio, 2.5; 95% confidence interval, 1. 0-5.8). CONCLUSION: A combination of human T lymphotropic virus type I infection and cardiovascular operation is believed to increase the potential risk of infectious complications shortly after the operation. However, this synergistic effect seems to be transient and has little influence on long-term prognosis. 相似文献
50.
Samuel R. Friedman Barbara Tempalski Hannah Cooper Theresa Perlis Marie Keem Risa Friedman Peter L. Flom 《Journal of urban health》2004,81(3):377-400
This article estimates the population prevalence of current injection drug users (IDUs) in 96 large US metropolitan areas
to facilitate structural analyses of its predictors and sequelae and assesses the extent to which drug abuse treatment and
human immunodeficiency virus (HIV) counseling and testing are made available to drug injectors in each metropolitan area.
We estimated the total number of current IDUs in the United States and then allocated the large metropolitan area total among
large metropolitan areas using four different multiplier methods. Mean values were used as best estimates, and their validity
and limitations were assessed. Prevalence of drug injectors per 10,000 population varied from 19 to 173 (median 60; interquartile
range 42–87). Proportions of drug injectors in treatment varied from 1.0% to 39.3% (median 8.6%); and the ratio of HIV counseling
and testing events to the estimated number of IDUs varied from 0.013 to 0.285 (median 0.082). Despite limitations in the accuracy
of these estimates, they can be used for structural analyses of the correlates and predictors of the population density of
drug injectors in metropolitan areas and for assessing the extent of service delivery to drug injectors. Although service
provision levels varied considerably, few if any metropolitan areas seemed to be providing adequate levels of services. 相似文献