全文获取类型
收费全文 | 16549篇 |
免费 | 1373篇 |
国内免费 | 529篇 |
专业分类
耳鼻咽喉 | 175篇 |
儿科学 | 281篇 |
妇产科学 | 377篇 |
基础医学 | 2123篇 |
口腔科学 | 334篇 |
临床医学 | 1976篇 |
内科学 | 2921篇 |
皮肤病学 | 311篇 |
神经病学 | 1090篇 |
特种医学 | 695篇 |
外国民族医学 | 3篇 |
外科学 | 2013篇 |
综合类 | 1378篇 |
一般理论 | 2篇 |
预防医学 | 1079篇 |
眼科学 | 444篇 |
药学 | 1453篇 |
4篇 | |
中国医学 | 383篇 |
肿瘤学 | 1409篇 |
出版年
2024年 | 30篇 |
2023年 | 170篇 |
2022年 | 420篇 |
2021年 | 603篇 |
2020年 | 337篇 |
2019年 | 433篇 |
2018年 | 432篇 |
2017年 | 389篇 |
2016年 | 395篇 |
2015年 | 557篇 |
2014年 | 666篇 |
2013年 | 719篇 |
2012年 | 1207篇 |
2011年 | 1316篇 |
2010年 | 783篇 |
2009年 | 667篇 |
2008年 | 946篇 |
2007年 | 914篇 |
2006年 | 885篇 |
2005年 | 802篇 |
2004年 | 724篇 |
2003年 | 607篇 |
2002年 | 527篇 |
2001年 | 466篇 |
2000年 | 404篇 |
1999年 | 396篇 |
1998年 | 151篇 |
1997年 | 151篇 |
1996年 | 176篇 |
1995年 | 147篇 |
1994年 | 110篇 |
1993年 | 85篇 |
1992年 | 195篇 |
1991年 | 182篇 |
1990年 | 156篇 |
1989年 | 134篇 |
1988年 | 128篇 |
1987年 | 108篇 |
1986年 | 105篇 |
1985年 | 103篇 |
1984年 | 77篇 |
1983年 | 70篇 |
1982年 | 56篇 |
1981年 | 55篇 |
1980年 | 47篇 |
1979年 | 60篇 |
1978年 | 50篇 |
1977年 | 33篇 |
1975年 | 27篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Subjects discriminated whether two sequentially presented human face pictures (S1 and S2) were identical while event-related potentials were recorded to explore the neural basis of visual completion for occluded objects. Four kinds of stimulus trials were employed: S2 and S1 were identical (match-complete); S2 and S1 were identical, but S2 was partially occluded (match-incomplete); S2 was a different face from S1 (mismatch-complete); S2 was different from S1, and was partially occluded (mismatch-incomplete). Incomplete faces enhanced the amplitude of N1 compared with complete faces. The peak latency of N2 elicited by incomplete faces was delayed about 20 ms compared with complete faces. The enhancement of N1 is related to visual completion processing that requires additional time. 相似文献
52.
Differential binding kinetics of cholera toxin to intestinal microvillus membrane during development 总被引:4,自引:1,他引:3
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A complete randomized block design was used to compare the binding kinetics of cholera toxin to developing rat enterocyte microvillus membranes prepared from newborn, 2-week-old, 4-week-old, and adult animals. Saturation-binding isotherms were generated on 16 independent samples (four blocks) under steady-state and reversible conditions. Scatchard analyses suggested positive cooperative binding to a single class of receptors, and the isotherms were analyzed by both the Hill-Waud and Michaelis-Menten functions. Receptor density varied significantly with age (P = 0.013). An abrupt rise in receptor density occurred after the neonatal period and normalized in the adult animal. The half-dissociation constant also varied significantly with age (P = 0.019). Microvillus membranes from suckling animals had a slightly higher apparent affinity than those from weaned animals. Neither receptor concentration nor membrane purity confounded these observations. Whereas age-related changes in apparent affinity correlated with cellular responses, changes in receptor density did not. This study suggests that developmental changes in membrane structure which influence binding affinity but not receptor density may, in part, contribute to the increased sensitivity of suckling rats to cholera toxin exposure. 相似文献
53.
Rat hemoglobins are unusually heterogeneous among mammals. This heterogeneity provides multiple opportunities for asynchronies in synthesis and degradation. We have examined rat hemoglobin turnover after an intravenous injection of 2-14C-glycine. After analyzing incorporation into the seven nonallelic globin chains of adult rats, we found the percentage of the major beta chain decreases over the red cell lifespan while the percentage of one of the minor beta chains increases. This suggests that a post-synthetic modification event converts a portion of the latter into the former. 相似文献
54.
Single photon emission computed tomography using 99mTc-HM-PAO in the routine evaluation of Alzheimer's disease 总被引:1,自引:0,他引:1
T A Hurwitz W Ammann D Chu C Clark J Holden R Brownstone 《The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques》1991,18(1):59-62
Regional cerebral blood flow was studied in 7 patients with clinically suspected Alzheimer's disease and 10 normal controls by single photon computed emission tomography (SPECT) using HM-PAO. All patients with Alzheimer's disease and no controls had parietal lobe hypoperfusion which was usually bilateral. In patients with more severe dementia hypoperfusion extended into the frontal lobes. Parietal lobe hypoperfusion corresponds to parietal lobe degeneration which is the one of the first neocortical regions to show the typical degenerative changes of Alzheimer's disease. SPECT with HM-PAO is a non-invasive investigation available in most nuclear medicine departments and complements existing tests in the routine evaluation of patients presenting with dementia. 相似文献
55.
W W Huurman F S Jacobsen J C Anderson W K Chu 《The Journal of bone and joint surgery. American volume》1987,69(5):699-705
A simple, rapid, and accurate method for measuring limb-length discrepancies with computerized axial tomographic equipment is described. With this method less irradiation is delivered and some of the errors of computation are eliminated, compared with conventional methods. The costs of the technique are comparable with those of scanograms. The method is particularly applicable in the patient who has contracture of a joint. 相似文献
56.
Comparison of hand-sewn and stapled esophagogastric anastomosis after esophageal resection for cancer: a prospective randomized controlled trial. 总被引:14,自引:0,他引:14
下载免费PDF全文
![点击此处可从《Annals of surgery》网站下载免费的PDF全文](/ch/ext_images/free.gif)
OBJECTIVE: The objective of this study was to compare the hand-sewn and stapled methods in esophagogastric anastomosis. SUMMARY BACKGROUND DATA: After esophageal resection for cancer, the relative merits of the hand-sewn and the stapled methods of esophagogastric anastomosis, especially regarding leakage and stricture rates, have not adequately been studied. METHODS: A prospective randomized controlled trial was undertaken in 122 patients with squamous cell cancer of the thoracic esophagus who underwent a Lewis-Tanner esophagectomy. Patients were stratified according to esophageal size, based on the diameter of the divided esophagus (< or > or = 30 mm) and then were randomized to have either a hand-sewn or a stapled anastomosis. RESULTS: The mean total operating times (standard error of the mean) when the hand-sewn and the stapled methods were used were 214 (4) minutes and 217 (3.4) minutes, respectively (p = not significant [NS]). The respective in vivo proximal resection margins (standard error of the mean) were 8 (0.4) cm and 7.6 (0.4) cm (p = NS). Leakage rates were 1.6% and 4.9% (p = NS). Excluding hospital deaths, patients with leakage or anastomotic recurrence, and those who received radiation therapy to histologically infiltrated resection margin, anastomotic stricture was found in 5 (9.1%) of 55 patients in the hand-sewn group and 20 (40%) of 50 in the stapler group (p = 0.0003). The difference in stricture rates was significant in small as well as large esophagi. Anastomotic recurrence developed in only one patient in each group. CONCLUSIONS: The authors conclude that both methods were safe, but the stapled technique resulted in more stricture formation. 相似文献
57.
58.
59.
无创性动态血压(ABPM)能较客观地反映血压水平及其昼夜变化规律,对高血压病的诊断、指导用药、药物疗效的评定以及预后评估等均有较大价值。本文对ABPM的发展及临床应用等问题进行综述。 相似文献
60.