全文获取类型
收费全文 | 201821篇 |
免费 | 41575篇 |
国内免费 | 2573篇 |
专业分类
耳鼻咽喉 | 5486篇 |
儿科学 | 6071篇 |
妇产科学 | 4211篇 |
基础医学 | 6159篇 |
口腔科学 | 6175篇 |
临床医学 | 42852篇 |
内科学 | 56142篇 |
皮肤病学 | 8279篇 |
神经病学 | 18685篇 |
特种医学 | 7515篇 |
外科学 | 46162篇 |
综合类 | 355篇 |
现状与发展 | 80篇 |
一般理论 | 4篇 |
预防医学 | 16903篇 |
眼科学 | 4678篇 |
药学 | 2212篇 |
中国医学 | 53篇 |
肿瘤学 | 13947篇 |
出版年
2024年 | 984篇 |
2023年 | 6774篇 |
2022年 | 1677篇 |
2021年 | 4344篇 |
2020年 | 7653篇 |
2019年 | 3234篇 |
2018年 | 10284篇 |
2017年 | 10322篇 |
2016年 | 11376篇 |
2015年 | 11656篇 |
2014年 | 19187篇 |
2013年 | 21208篇 |
2012年 | 7951篇 |
2011年 | 7922篇 |
2010年 | 12956篇 |
2009年 | 17376篇 |
2008年 | 7969篇 |
2007年 | 6086篇 |
2006年 | 8720篇 |
2005年 | 5629篇 |
2004年 | 4474篇 |
2003年 | 3326篇 |
2002年 | 3322篇 |
2001年 | 4555篇 |
2000年 | 3430篇 |
1999年 | 3951篇 |
1998年 | 4569篇 |
1997年 | 4362篇 |
1996年 | 4310篇 |
1995年 | 3991篇 |
1994年 | 2586篇 |
1993年 | 2127篇 |
1992年 | 1820篇 |
1991年 | 1760篇 |
1990年 | 1378篇 |
1989年 | 1463篇 |
1988年 | 1291篇 |
1987年 | 1072篇 |
1986年 | 1088篇 |
1985年 | 898篇 |
1984年 | 718篇 |
1983年 | 692篇 |
1982年 | 650篇 |
1981年 | 543篇 |
1980年 | 431篇 |
1979年 | 358篇 |
1978年 | 408篇 |
1977年 | 465篇 |
1975年 | 321篇 |
1972年 | 348篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Timothy C. Evans MD PhD ; Keren H. Wick PhD ; Douglas M. Brock PhD ; Douglas C. Schaad PhD ; Ruth Ballweg MPA PA-C 《The Journal of rural health》2006,22(3):212-219
CONTEXT: The physician assistant profession has been moving toward requiring master's degrees for new practitioners, but some argue this could change the face of the discipline. PURPOSE: To see if there is an association between physician assistants' academic degrees and practice in primary care, in rural areas, and with the medically underserved. METHODS: Surveys were sent to 880 graduates of the first 32 University of Washington physician assistant classes through 2000. Respondents noted their academic degree at program entry and the highest degree attained at any time up to the time of survey. Relationships between practice characteristics and academic degree levels were tested by unadjusted odds ratios and logistic regression after controlling for year of graduation and sex. RESULTS: Of the 478 respondents, 54% worked in primary care, about 30% practiced in nonmetropolitan communities, and 42% reported providing care for the medically underserved. Respondents with no degree (33% of total at entry, 24% at survey) were significantly more likely than degree holders to work in primary care and nonmetropolitan areas. Respondents with no degree at program entry were significantly more likely, and those with no degree at the time of the survey were marginally more likely, to self-report work with the medically underserved. CONCLUSION: Respondents with no academic degree are significantly more likely to demonstrate a commitment to primary, rural, and underserved health care. These findings may inform the national debate about the impact of required advanced degrees on the practice patterns of nonphysician providers. 相似文献
24.
25.
26.
27.
Manuel Neves-E-Castro 《Gynecological endocrinology》2006,22(4):190-197
Dormant breast cancer cells are a reality that cannot be overlooked. They may stay dormant either after a spread of cancer cells caused by surgery or after being generated by spontaneous or induced mutations in the course of breast gland growth. Some cases are presented in support of both possibilities, followed by a critical appraisal of the factors that may either keep them dormant or later stimulate their growth into a breast cancer. 相似文献
28.
Jorge Guardado Carlos Cotrim Otília Sim?es Sofia Almeida Mário Ialá Luís Lopes Hélder Pereira Manuel Carrageta 《Revista portuguesa de cardiologia》2006,25(4):409-415
INTRODUCTION: Transesophageal echocardiography (TEE) has become increasingly useful in the study of patients with suspected pulmonary thromboembolism. OBJECTIVE: The aim of this study was to prospectively evaluate the usefulness of TEE in the study of the distal part of the left pulmonary artery (LPA) as well as the influence of this procedure on total echocardiographic exam duration. METHODOLOGY: A prospective study in two groups of consecutive patients referred for TEE with a one- year interval between evaluation of Group A: 33 patients, 17 male, mean age 54 +/- 24 years, and Group B: 42 patients, 20 male, mean age 48 +/- 27 years (p = NS). The procedure was considered long when it took more than 3 min to evaluate the distal part of the LPA. RESULTS: In group A we were able to visualize the distal part of the LPA in 24 patients (73%) without significant prolongation of total exam duration in 16 patients (48% of group A). In one of the patients with suspected pulmonary thromboembolism thrombi were only observed in the distal part of the LPA. In group B we were able to visualize the distal part of the LPA in 36 patients (86%) without significant prolongation of total exam duration in 26 patients (61% of group B). CONCLUSIONS: 1. Visualization of the distal part of the LPA was possible in more patients, and with TEE time prolongation in less patients, in group B. These differences can be accounted for by the training of the operator in this technique. 2. The importance of visualization of this part of the LPA in guiding treatment in the subset of patients with pulmonary thromboembolism confirms the usefulness of this specific procedure. 相似文献
29.
The aim of this study was to design a new intravenous blood–gas exchange device and to estimate the design characteristics
of the device with a dimensionless function by using a substance that can be used instead of bovine blood. In addition, the
characteristics of oxygen transfer were estimated using empirical formulas and the reliability of the equations was ascertained
by comparing their output with an experiment performed using bovine blood. The dimensionless function was derived using distilled
water and bovine blood to estimate the oxygen transfer rate. Using the derived equations, the calculated oxygen transfer rates
for bovine blood and distilled water were similar for Reynolds numbers ranging from 0.7 to 7.0. Therefore, it is possible
to estimate the oxygen transfer rate in bovine blood, which is a non-Newtonian fluid, using distilled water, which is a Newtonian
fluid. Moreover, it was possible to verify the related equations because the oxygen transfer rate could be estimated using
the derived equations, according to the diameters of the various device modules. 相似文献
30.