全文获取类型
收费全文 | 13357篇 |
免费 | 1222篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 117篇 |
儿科学 | 353篇 |
妇产科学 | 380篇 |
基础医学 | 2084篇 |
口腔科学 | 148篇 |
临床医学 | 1850篇 |
内科学 | 2400篇 |
皮肤病学 | 213篇 |
神经病学 | 1215篇 |
特种医学 | 303篇 |
外科学 | 1451篇 |
综合类 | 236篇 |
一般理论 | 29篇 |
预防医学 | 1667篇 |
眼科学 | 398篇 |
药学 | 1008篇 |
中国医学 | 25篇 |
肿瘤学 | 719篇 |
出版年
2023年 | 101篇 |
2022年 | 116篇 |
2021年 | 288篇 |
2020年 | 222篇 |
2019年 | 330篇 |
2018年 | 373篇 |
2017年 | 289篇 |
2016年 | 306篇 |
2015年 | 331篇 |
2014年 | 472篇 |
2013年 | 655篇 |
2012年 | 905篇 |
2011年 | 896篇 |
2010年 | 483篇 |
2009年 | 429篇 |
2008年 | 712篇 |
2007年 | 752篇 |
2006年 | 724篇 |
2005年 | 713篇 |
2004年 | 669篇 |
2003年 | 615篇 |
2002年 | 546篇 |
2001年 | 219篇 |
2000年 | 203篇 |
1999年 | 182篇 |
1998年 | 139篇 |
1997年 | 109篇 |
1996年 | 103篇 |
1995年 | 98篇 |
1994年 | 89篇 |
1993年 | 88篇 |
1992年 | 140篇 |
1991年 | 139篇 |
1990年 | 120篇 |
1989年 | 132篇 |
1988年 | 128篇 |
1987年 | 130篇 |
1986年 | 125篇 |
1985年 | 140篇 |
1984年 | 116篇 |
1983年 | 85篇 |
1982年 | 79篇 |
1981年 | 56篇 |
1980年 | 67篇 |
1979年 | 100篇 |
1978年 | 79篇 |
1977年 | 52篇 |
1974年 | 77篇 |
1973年 | 62篇 |
1972年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
41.
42.
43.
A Srivastava D J Webster J P Woodcock S Shrotria R E Mansel L E Hughes 《The British journal of surgery》1988,75(9):851-853
One hundred and five patients with discrete breast lumps were examined with a 10 MHz Doppler ultrasonic flowmeter. Doppler flow signals were analysed on an Angioscan spectrum analyser. Recordings from the opposite normal breast were taken as controls and signals from the two sides compared. In 23 patients signals from the normal breast could not be recorded and therefore results of the remaining 82 patients are reported. These included 39 patients with carcinoma, 20 with fibroadenoma, 12 with cyclical nodularity and 11 with cysts. Malignant lumps exhibited significantly higher peak systolic (S) and minimum diastolic frequencies (D) in comparison to the control breast. Fibroadenoma also had a higher S and D than those of the opposite normal breast. Signals over cysts and cyclical nodularity showed no significant difference from the recordings over the control side. Despite significantly higher systolic and diastolic frequencies in the cancer group in comparison to benign lumps and normal breast, considerable overlap in the values was seen between cancer and other groups. Therefore the patterns on 10 MHz Doppler sonography are not sufficiently specific to discriminate benign from malignant breast lumps. 相似文献
44.
45.
46.
Marjolein Gysels Rhidian Hughes Fiona Aspinal Julia M Addington-Hall Irene J Higginson 《International journal for quality in health care》2004,16(5):375-381
OBJECTIVE: To investigate the opinions of stakeholders (service commissioners and providers) on how performance data should be presented, in order to develop effective feedback methods to facilitate the use of these data in decision making. DESIGN: A qualitative analysis of semi-structured face-to-face and telephone interviews. League tables and fictional box plots were presented as an illustrative guide. The themes covered in the interviews were the effectiveness of these two feedback formats, their positive and negative characteristics, and ideas for new and improved feedback mechanisms. PARTICIPANTS: Thirty-six stakeholders representing a range of clinical and non-clinical roles within palliative care and the wider health care system across a variety of statutory and non-statutory organizations from London and the West Midlands. RESULTS: Box plots were received more positively than league tables, and qualitative information was considered more appropriate than pictorial feedback. Conventional methods such as league tables and box plots were judged to lack essential information on which important decisions could be based, such as additional contextual information and the methodological assumptions of the instrument. Both feedback methods were considered useful as an impetus to further discussion. There was a consensus that feedback should be constructive and able to be adapted to the organizational realities in which UK health services function. CONCLUSION: Qualitative research was viewed as the right evidence for gaining an understanding of the quality of end of life care. Stakeholders highlighted the importance of the lay perspective, which requires approaches that illuminate the subjective meanings of patient experience. 相似文献
47.
Cell type-specific gene expression in the neuroendocrine system. A neuroendocrine-specific regulatory element in the promoter of chromogranin A, a ubiquitous secretory granule core protein. 总被引:5,自引:1,他引:4
下载免费PDF全文
![点击此处可从《The Journal of clinical investigation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H Wu D J Rozansky N J Webster D T O'Connor 《The Journal of clinical investigation》1994,94(1):118-129
48.
The effect of cadmium on the respiration of Ulva lactuca was examined using an oxygen electrode. Discs of U. lactuca thallus in filtered seawater were either incubated in the dark for 24 h or treated with 20 μM 3(3,4-dichlorophenyl) 1,1-dimethylurea to inhibit photosystem II dependent noncyclic electron transfer. In both cases, the addition of cadmium, as sulphate, increased respiration, with maximum stimulation occurring at approximately 15 mM; above this concentration respiration declined and at >21 mM inhibitory effects were significant. Dinitrophenol (DNP, 50 μM) and carbonyl cyanide m-chlorophenylhydrazone (CCCP, 10 μM) also uncoupled respiration of U. lactuca, and when these compounds were used in conjunction with Cd the effects were found to be additive. Oligomycin (12.5 μ mL?1), which inhibits the mitochondrial ATPase, inhibited U. lactuca respiration but subsequent Cd addition (to 6 mM) resulted in a 2.5 × increase in respiration over control values. DNP had a similar effect when used with oligomycin. DNP and CCCP had a negligible effect on the respiration of KCN-treated discs but the addition of Cd restored respiration to control values, probably because of the formation of insoluble Cd(CN)2. These results demonstrate that Cd can act as a respiratory uncoupler in U. lactuca. 相似文献
49.
Transcutaneous oxygen tension (TcPO2) measurement has been successfully applied to the diagnosis and monitoring of patients with peripheral arterial insufficiency. This study was performed to assess the effects of changes in limb position, oxygen inhalation, and arterial reconstruction on TcPO2 values in patients with peripheral vascular disease. In addition, a TcPO2 index (foot TcPO2/chest TcPO2) was compared with the Doppler-derived ankle-to-brachial index (ABI) to determine which was the more effective monitor of the response to revascularization. Foot TcPO2 values of 22 patients with claudication or rest pain were measured before and after vascular reconstruction. TcPO2 increased after revascularization in both groups regardless of limb position or oxygen (O2) administration. The dependent position and O2 inhalation had an additive effect on TcPO2. Preoperative TcPO2 values in patients with rest pain showed the greatest response to the dependent position, increasing from 14 mm Hg to 33 mm Hg at room air and from 21 mm Hg to 53 mm Hg with O2 inhalation. TcPO2 in both patient groups was remarkably enhanced by O2 administration after revascularization. Postoperative supine TcPO2 values measured at room air increased from 50 mm Hg to 124 mm Hg (148%) in patients with claudication and from 40 mm Hg to 109 mm Hg (173%) in patients with rest pain after O2 inhalation. Comparison of the TcPO2 index with the ABI showed that absolute and normalized TcPO2 values are equally effective in monitoring peripheral arterial insufficiency. This study suggests that placing the limb in the dependent position and administering O2 may augment TcPO2 to levels where symptoms may resolve. The response of TcPO2 to O2 inhalation may be an indicator that reflects the response to revascularization. 相似文献
50.
The physiological regulation of toll-like receptor expression and function in humans 总被引:5,自引:0,他引:5
Graeme I. Lancaster Qamar Khan Pam Drysdale Fiona Wallace Asker E. Jeukendrup Mark T. Drayson Michael Gleeson 《The Journal of physiology》2005,563(3):945-955
Eleven mammalian toll-like receptors (TLRs 1–11) have been identified to date and are known to play a crucial role in the regulation of immune responses; however, the factors that regulate TLR expression and function in vivo are poorly understood. Therefore, in the present study, we investigated the physiological regulation of TLR expression and function in humans. To examine the influence of diurnal rhythmicity on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 8) at time points coinciding with the peak and nadir in the endogenous circulating cortisol concentration. While no diurnal rhythmicity in the expression of TLRs 1, 2, 4 or 9 was observed, the upregulation of costimulatory (CD80 and CD86) and antigen-presenting (MHC class II) molecules on CD14+ monocytes following activation with specific TLR ligands was greater ( P < 0.05) in samples obtained in the evening compared with the morning. To examine the influence of physical stress on TLR expression and function, peripheral venous blood samples were collected from healthy volunteers ( n = 11) at rest and following 1.5 h of strenuous exercise in the heat (34°C). Strenuous exercise resulted in a decrease ( P < 0.005) in the expression of TLRs 1, 2 and 4 on CD14+ monocytes. Furthermore, the upregulation of CD80, CD86, MHC class II and interleukin-6 by CD14+ monocytes following activation with specific TLR ligands was decreased ( P < 0.05) in samples obtained following exercise compared with at rest. These results demonstrate that TLR function is subject to modulation under physiological conditions in vivo and provide evidence for the role of immunomodulatory hormones in the regulation of TLR function. 相似文献