全文获取类型
收费全文 | 21523篇 |
免费 | 1388篇 |
国内免费 | 420篇 |
专业分类
耳鼻咽喉 | 154篇 |
儿科学 | 914篇 |
妇产科学 | 414篇 |
基础医学 | 3335篇 |
口腔科学 | 448篇 |
临床医学 | 2094篇 |
内科学 | 2311篇 |
皮肤病学 | 311篇 |
神经病学 | 1289篇 |
特种医学 | 1886篇 |
外国民族医学 | 8篇 |
外科学 | 1792篇 |
综合类 | 2386篇 |
一般理论 | 1篇 |
预防医学 | 3219篇 |
眼科学 | 316篇 |
药学 | 822篇 |
18篇 | |
中国医学 | 430篇 |
肿瘤学 | 1183篇 |
出版年
2024年 | 56篇 |
2023年 | 389篇 |
2022年 | 780篇 |
2021年 | 917篇 |
2020年 | 872篇 |
2019年 | 808篇 |
2018年 | 755篇 |
2017年 | 644篇 |
2016年 | 618篇 |
2015年 | 638篇 |
2014年 | 1305篇 |
2013年 | 1368篇 |
2012年 | 1054篇 |
2011年 | 1284篇 |
2010年 | 1075篇 |
2009年 | 1117篇 |
2008年 | 1207篇 |
2007年 | 1171篇 |
2006年 | 978篇 |
2005年 | 844篇 |
2004年 | 703篇 |
2003年 | 602篇 |
2002年 | 535篇 |
2001年 | 413篇 |
2000年 | 389篇 |
1999年 | 286篇 |
1998年 | 290篇 |
1997年 | 261篇 |
1996年 | 243篇 |
1995年 | 210篇 |
1994年 | 184篇 |
1993年 | 150篇 |
1992年 | 114篇 |
1991年 | 102篇 |
1990年 | 65篇 |
1989年 | 71篇 |
1988年 | 60篇 |
1987年 | 67篇 |
1986年 | 48篇 |
1985年 | 99篇 |
1984年 | 68篇 |
1983年 | 55篇 |
1982年 | 46篇 |
1981年 | 55篇 |
1980年 | 59篇 |
1979年 | 50篇 |
1978年 | 48篇 |
1977年 | 23篇 |
1976年 | 35篇 |
1973年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The energetics of middle-distance running 总被引:3,自引:0,他引:3
J. R. Lacour S. Padilla-Magunacelaya J. C. Barthélémy D. Dormois 《European journal of applied physiology》1990,60(1):38-43
Summary In order to assess the relative contribution of aerobic processes to running velocity (v), 27 male athletes were selected on the basis of their middle-distance performances over 800, 1500, 3000 or 5000 m, during the 1987 track season. To be selected for study, the average running velocity
corresponding to their performances had to be superior to 90% of the best French
of the season. Maximum O2 consumption
and energy cost of running (C) had been measured within the 2 months preceding the track season, which, together with oxygen consumption at rest
allowed us to calculate the maximalv that could be sustained under aerobic conditions:
. The treadmill runningv corresponding to a blood lactate of 4 mmol·–1 (v
la4), was also calculated. In the whole group, C was significantly related to height (r=–0.43;P<0.03). Neither C nor
(with, in this case, the exception of the 3000 m athletes) were correlated to
. On the other hand,v
a max was significantly correlated to
over distances longer than 800 m. These
were also correlated tov
la4. Howeverv
la4 occurred at 87.5% SD 3.3% ofv
a max, this relationship was interpreted as being an expression of the correlation betweenv
a max and
. Calculation ofv
a max provided a useful means of analysing the performances. At the level of achievement studied,
sustained over 3000 m corresponded tov
a max. The shape of the relationship ofv/v
a max as a function of the duration of the event raised the question of a possible change in C as a function of v during middle-distance running competitions. 相似文献
102.
Wilson TE Johnson SC Petajan JH Davis SL Gappmaier E Luetkemeier MJ White AT 《European journal of applied physiology》2002,88(1-2):67-75
This study compared the effects of pre-exercise cooling with control water immersions on exercise-induced thermal loads derived
from steady-state submaximal exercise. Eight healthy male participants [mean (SEM) age 29 (1) years, maximal oxygen uptake
3.81 (0.74) l·min–1, and body surface area 1.85 (0.11) m2] took part in experiments that included 30 min of baseline data collection [ambient temperature 21.3 (0.2°C)], 30 min of
immersion in water to the level of the supra-iliac crest [water temperatures of 35.1 (0.3)°C for thermoneutral and 17.7 (0.5)°C
for precooled treatments], and 60 min of cycling exercise at 60% of maximal oxygen uptake. No significant differences were
noted during exercise in net mechanical efficiency, metabolic rate, O2 pulse, or ratings of perceived exertion between the two treatments. Precooling resulted in a significant negative body heat
storage during immersion and allowed greater heat storage during exercise. However, net body heat storage for the entire protocol
was no different between treatments. Cooling significantly lowered rectal, mean skin, and mean body temperatures as well as
more than doubling the exercise time until a 0.5°C rectal temperature increase was observed. The cooling trial significantly
delayed onset of sweating by 19.62 min and decreased sweat rate by 255 ml·h–1 compared to control. Thermal and sweat sensation scores were lower after the cooling treatment compared to control. These
data suggest that lower-body precooling is effective at decreasing body heat storage prior to exercise and decreases reliance
on heat dissipation mechanisms during exercise. Therefore, this unique, well-tolerated cooling treatment should have a broader
application than other precooling treatments.
Electronic Publication 相似文献
103.
Michael H. Stone Michael E. Rush Harry Lipner 《Pflügers Archiv : European journal of physiology》1978,375(2):147-151
The hormonal levels of the gonadotropins, the weight of selected organs and of the triceps surae as well as body composition were determined in Sprague Dawley rats at 3 and 6 weeks after intensive training with or without a methandrostenelone (Dianabol) supplement (0.35 mg/kg/day). The controls were sedentary rats of similar age and weight at the start of the experiment. The dianabol treated rats in the sedentary and exercise groups had a depression of plasma LH levels. There were no differences in body weight, specific gravity, lean body weight, fat or % fat between the two trained groups. Dianabol had no apparent effect on the measured parameters other than a depression of LH. 相似文献
104.
原发性中枢神经系统恶性淋巴瘤MR表现及其病理学基础 总被引:5,自引:0,他引:5
目的 研究原发性中枢神经系统恶性淋巴瘤(PCNSL)的MR表现及其病理学基础。方法 分析13例手术病理证实的原发性中枢神经系统恶性淋巴瘤的临床病理及MR表现。结果 13例中单发肿瘤4例,多发肿瘤9例,共计36个病灶。13例病变均累及幕上,其中8例病灶位于深部脑白质近脑室旁。肿瘤平均最大径为3.2cm。T1WI略低信号28个,T2WI等信号24个。28个病灶呈均匀强化。肿瘤水肿及占位效应相对较轻。2例PCNSL行MR动态增强扫描,早期强化均不明显,时间-信号强度曲线呈缓慢上升型。病理上肿瘤细胞弥漫分布,瘤细胞大小较一致,细胞质少,细胞核大,染色质颗粒粗,可见瘤细胞围绕血管呈袖套样浸润,少见明显的出血及片状坏死,未见钙化,病理均为非霍奇金淋巴瘤。结论 原发性中枢神经系统恶性淋巴瘤的病理基础决定其MR增强形态、占位程度以及肿瘤发生部位具有一定特征,运用不同的MR影像学检查方法和技术,在多数情况下可以做出术前正确诊断。 相似文献
105.
Haijo Jung Hee-Joung Kim Sang-Ho Lee Sae-Rome Kim Chang Lyong Ji Jung-Han Kim Sun Kook Yoo Ki-Hwang Kim 《Journal of digital imaging》2004,17(2):100-108
This study evaluated the migration to full-PACS of medical image data archived using mini-PACS at two hospitals of the Yonsei University Medical Center, Seoul, Korea. A major concern in the migration of medical data is to match the image data from the mini-PACS with the hospital OCS (Ordered Communication System). Prior to carrying out the actual migration process, the principles, methods, and anticipated results for the migration with respect to both cost and effectiveness were evaluated. Migration gateway workstations were established and a migration software tool was developed. The actual migration process was performed based on the results of several migration simulations. Our conclusions were that a migration plan should be carefully prepared and tailored to the individual hospital environment because the server system, archive media, network, OCS, and policy for data management may be unique. 相似文献
106.
通过对乳腺肿瘤边界特征的分析,得到边界的特征量似圆度,面积比率,长宽比组成的特征矢量,最后用反向传播人工神经网络(BP)的算法对经病理证实的119幅乳腺良、恶性肿块超声图像进行分类识别。BP神经网络对良、恶性肿瘤正确识别率分别为89.7%、73.5N。量化后的乳腺超声图像肿瘤轮廓特征结合BP神经网络可以比较有效的用于肿瘤的良、恶性识别。 相似文献
107.
本文用计算机图象处理技术对细胞显微图象进行处理和定量分析,求出了细胞面积在低温保存中极其重要的参数。实验证明,计算机测量比人工精度高,误差小,同时新颖的标号去噪方法也非常有效。 相似文献
108.
E. Obál Jr. G. Benedek A. Jancsó-Gábor F. Obál 《Pflügers Archiv : European journal of physiology》1979,382(3):249-254
Salivary thermolytic mechanism (weight of salivary glands, effect of desalivation on water intake and body temperature, grooming activity) as well as escape behaviour and reaction to heat pain were studied in capsaicin-desensitized and control rats exposed to various warm ambient temperatures. Body temperature of the desensitized rats increased more than the controls at all the ambient temperatures studied (32, 34 and 36°C); however, significant differences in the mechanism of salivary cooling were obtained only at 34 and 36°C. Central impairment of saliva spreading in desensitized rats seems evident. Complete surgical desalivation did not increase hyperthermia of control and desensitized animals in warm environments. Therefore other mechanisms, primarily vasodilatatory, must also be involved in the rat's thermolytic normal response. Although desensitized rats did not show a tendency to escape from the warm environment their response to heat pain was normal. In conclusion, it is suggested that heat perception in desensitized animals is impaired; however, the existence of some capsaicin-insensitive thermolytic mechanisms (prone extension of the body) cannot be excluded.Supported by the Scientific Research Council, Ministry of Health, Hungary /4-05-0303-04-2/0/ and MTA-OM-MÉM-EÜM 70.211/79 相似文献
109.
Central amygdaloid nucleus lesions in rats had no effect on recovery of preoperative body weight and food consumption levels. The brain damaged rats also recovered preoperative levels of water consumption as rapidly as control rats but then developed a mild but persistent hypodipsia. The experimental rats also drank less than control rats when food deprived and showed marginally reliable decreases in 0.1% quinine solution consumption and latency to consume a novel food. There was no detectable lesion effect on 0.1% saccharin solution consumption, exploration of a novel environment or formation of a learned taste aversion. It is suggested that the central amygdaloid nucleus has a role in mediating the relationship between food and water intake and in some taste mediated consummatory behavior. 相似文献
110.
Professor K. M. Patil M. S. Srinath 《Medical & biological engineering & computing》1990,28(5):416-422
A new image-processing system, using a video digitiser with an IBM-compatible PC/AT, is developed for acquisition and processing
of low-contrast, lowintensity barographic images of both feet for assessment of pressure distribution during standing and
walking. Data displays, in the form of centres of pressures, isopressures contours, perspective views of pressures, grey scale
image and walking pressure patterns, combined image of walking pressures, paths of centres of pressures and pressure variations
with time, are developed. These have provided very useful and early information regarding the internal structural changes
in the bones of the foot and sites at risk of ulcer development in leprosy subjects and enable suitable corrective orthopaedic
procedures to be adopted.
unitl the end of November 1990, and will then return to the Indian Institute of Technology. 相似文献