全文获取类型
收费全文 | 16306篇 |
免费 | 1600篇 |
国内免费 | 528篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 295篇 |
妇产科学 | 159篇 |
基础医学 | 1964篇 |
口腔科学 | 97篇 |
临床医学 | 3474篇 |
内科学 | 3704篇 |
皮肤病学 | 54篇 |
神经病学 | 1063篇 |
特种医学 | 1576篇 |
外科学 | 946篇 |
综合类 | 1277篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 1906篇 |
眼科学 | 73篇 |
药学 | 820篇 |
12篇 | |
中国医学 | 466篇 |
肿瘤学 | 470篇 |
出版年
2024年 | 49篇 |
2023年 | 340篇 |
2022年 | 493篇 |
2021年 | 882篇 |
2020年 | 878篇 |
2019年 | 768篇 |
2018年 | 730篇 |
2017年 | 724篇 |
2016年 | 659篇 |
2015年 | 633篇 |
2014年 | 971篇 |
2013年 | 1341篇 |
2012年 | 834篇 |
2011年 | 782篇 |
2010年 | 714篇 |
2009年 | 636篇 |
2008年 | 711篇 |
2007年 | 629篇 |
2006年 | 551篇 |
2005年 | 436篇 |
2004年 | 419篇 |
2003年 | 404篇 |
2002年 | 328篇 |
2001年 | 353篇 |
2000年 | 311篇 |
1999年 | 257篇 |
1998年 | 218篇 |
1997年 | 199篇 |
1996年 | 212篇 |
1995年 | 196篇 |
1994年 | 141篇 |
1993年 | 175篇 |
1992年 | 189篇 |
1991年 | 135篇 |
1990年 | 123篇 |
1989年 | 111篇 |
1988年 | 131篇 |
1987年 | 131篇 |
1986年 | 98篇 |
1985年 | 97篇 |
1984年 | 73篇 |
1983年 | 47篇 |
1982年 | 68篇 |
1981年 | 50篇 |
1980年 | 66篇 |
1979年 | 37篇 |
1978年 | 20篇 |
1977年 | 19篇 |
1976年 | 21篇 |
1975年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
M. KROTKIEWSKI L. SJ
STR
M L. SULLIVAN P.-A. LUNDBERG G. LINDSTEDT H. WETTERQVIST P. BJ
RNTORP 《Journal of internal medicine》1984,216(3):269-275
Abstract Thyroid hormones were measured before, during and after acute exercise (60 min) or physical training (3 months) in obese women. Thyroid stimulating hormone concentration increased during acute work and decreased immediately after. No changes were seen during the two following days. An increase was seen after ten days as well as after three months of physical training. Thyroxine concentrations showed no changes. 3,5,3′-Triiodothyronine decreased slightly immediately after acute exercise, and after three months of physical training, 3,3′,5′-triiodothyronine (reverse triiodothyronine) increased slowly during and after acute exercise. A negative correlation was found between changes in fasting insulin and thyroxine and a positive correlation between changes in blood pressure and triiodothyronine after training. Lack of agreement in previous reports is probably due to methodological differences such as methods more or less susceptible to fatty acid interference, and thyroid hormones changing differently during acute work and before and after physical training. The duration of the study may also be of importance, even 3 months possibly being too short for attaining equilibrium in thyroid homeostasis. 相似文献
73.
医德重建:传统医德危机及其解决途径探析 总被引:1,自引:0,他引:1
目前,我国面临的医德危机是非常严重的。如何解决这一危机就成了一个不容回避的重大课题,不少学者提出要用传统医德来规范医务人员,并以此作为解决该危机的良方。然而,这种以人格伦理为特质的传统医德尽管有其一定的合理性,但其在实践中的有效性却受到了人们的质疑。为此,试图从传统医德自身的局限性、医务人员利益意识的觉醒以及因社会失范而导致的越轨三个方面来分析我国医德危机产生的根源,并为此提出了三条对策。 相似文献
74.
I. L. Kanstrup J. Marving N. Gadsbøll H. Lønborg-Jensen P. F. Høilund-Carlsen 《European journal of applied physiology》1995,72(1-2):86-94
Left ventricle systolic and diastolic functional parameters were measured by gated equilibrium radionuclide cardiography in 12 healthy men (age 33–51 years) at rest and during graded supine exercise. The leftventricle end-diastolic volume showed an initial small (11%) increase during low submaximal exercise [from mean 163 (SD 40) at rest to mean 181 (SD 48) ml], while left ventricle end-systolic volume decreased successively [from mean 59 (SD 19) to mean 39 (SD 21) ml] with increasing exercise. Stroke volume was therefore elevated at all exercise levels compared with rest [mean 104 (SD 23) ml], and the peak value [mean 128 (SD 33) ml] was found at the lowest exercise level, contributing 40% to the initial increase in cardiac output. Cardiac output increased from mean 6.2 (SD 1.4) at rest to mean 20.2 (SD 5.0) 1 · min–1 at maximum. Left ventricle peak ejection and peak filling rates increased from mean 449 (SD 89) and mean 442 (SD 85) ml · s–1 at rest to mean 996 (SD 227) and mean 1255 (SD 333) ml · s–1, respectively, at maximum. The myocardium oxygen consumption, assumed to be proportional to the sum of the stroke work and the potential energy, increased fourfold, but absolute values were twice as high as expected, indicating that extrapolation from data obtained in dog hearts (as we have done) cannot be directly applied to humans. Selected vaso-active hormones were measured at all exercise intensities. Noradrenaline (NA), adrenaline (A) and angiotensin II (AII) concentrations showed a very pronounced increase at maximal exercise compared with the preceding lower intensites, while atrial natriuretic factor (ANF) and cyclic guanosinemonophosphate (cGMP) concentrations showed a more continuous increase, and dopamine (DA) remained almost unchanged. This speaks in favour of a crucial role for NA, A and AII in preserving blood pressure at maximum exercise, while DA probably has no importance for the cardiovascular homeostasis during exercise. Increases in concentrations of ANF and cGMP were highly correlated (r = 0.86). Our data supported the opinion that there is a cardiac limitation to maximal performance connected to the cardiac pumping capacity. 相似文献
75.
76.
The effects of brisk walking on markers of bone and calcium metabolism in postmenopausal women 总被引:5,自引:0,他引:5
Weight-bearing exercise has been shown to maintain or increase bone mass in younger as well as older individuals but the mechanisms
by which mechanical loading affects bone metabolism are not known in detail. Twelve postmenopausal women participated in a
single bout of brisk walking (50% of VO2 max) for 90 minuttes. Calciotropic hormones and markers of type I collagen formation (PICP) and degradation (ICTP) were measured
before the exercise, and 1, 24, and 72 hours following the exercise. Total body bone mineral content (BMC) and density (BMD)
were measured by dual energy X-ray absorptiometry (DXA). Brisk walking did not induce any significant changes in the concentrations
of ionized calcium, parathyroid hormone (PTH), calcitonin, or osteocalcin. A significant increase of PICP was noted 24 and
72 hours (P<0.01) after exertion and a significant decrease in the concentration of serum ICTP at 1 hour (P<0.05) was followed by an increase at 72 hours (P<0.001). There was no significant difference between the increases in the concentrations of PICP and ICTP at 72 hours. Strong
inverse correlations between the basal levels of PTH and BMD (r=−0.78;P<0.01) as well as between osteocalcin and BMD (r=−0.83;P<0.01) were noticed. The changes in serum levels of bone collagen markers indicate an altered bone collagen turnover due to
this moderate endurance exercise. The results also support the fact that serum levels of PTH as well as those of osteocalcin
are associated with total body BMD in postmenopausal women. 相似文献
77.
Short and long term effects of exercise training on the tonic autonomic modulation of heart rate variability after myocardial infarction 总被引:3,自引:0,他引:3
Malfatto G.; Facchini M.; Bragato R.; Branzi G.; Sala L.; Leonetti G. 《European heart journal》1996,17(4):532-538
We studied the effects of cardiac rehabilitation on the sympathovagalcontrol of heart rate variability in 30 patients after a first,uncomplicated myocardial infarction. Twenty-two patients completed8 weeks of endurance training (trained), while eight decidednot to engage in the rehabilitation programme for logisticalreasons, and were taken as untrained controls. Age, site ofinfarction, ejection fraction, ventricular diameter and stresstest duration were similar in the two groups at baseline. Heartrate variability was evaluated 4 weeks after infarction beforestarting rehabilitation, and repeated 8 weeks and one year laterin both trained and untrained patients. Measures of heart ratevariability, obtained from both time- and frequency- domainanalysis of a 15 min ECG recording in resting conditions, wereas follows: mean RR interval and its standard deviation (RRSD),the mean square successive differences (MSSD), the percent ofRR intervals differing >50 ms from the preceding RR (pNTN50),the low and high frequency components of the autoregressivepower spectrum of the RR intervals and their ratio (LF/HF).At baseline, heart rate variability was similar in trained anduntrained patients. In the short term (8 weeks after infarction),training increased RRSD by 25% (P<0·01), MSSD by 69%(P<0·01), pNN50 by 120% (P<0·01), and reducedLF/HF ratio by 30% (P<0·01). The effects persistedafter one year in trained patients. In untrained patients, theautonomic control of heart rate variability did not change 8weeks after myocardial infarction and was only slightly modifiedby time. Thus, exercise training, performed for 8 weeks aftera myocardial infarction, modifies the sympathovagal controlof heart rate variability toward a persistent increase in parasympathetictone, known to be associated with a better prognosis. This maypartly account for the favourable outcome of patients who undergorehabilitation. 相似文献
78.
采用逐级负荷踏车实验和阻抗心动图的方法,测定居住3417m高原13~16岁藏汉族青少年静息状态下,运动后即刻及恢复期心率和左心收缩间期,结果显示,静息状态下两组STI各数值无差异,藏族运动后即刻的PEP短于汉族,LVET长于汉族,P/L有明显差异(P<0.01),经心率矫正后藏族运动后即刻LVETI及QS_2I均长于汉族,恢复期短于汉族,形成交叉曲线,说明居住高原的汉藏族人群的心功能差别在青少年时已经出现。提示:藏族在运动状态下有良好的心力储备及对运动负荷的适应能力,其原因可能与生长发育的环境及种群遗传有关。 相似文献
79.
The primary purpose of this study was to define regional blood flow in dogs with chronic tricuspid regurgitation (TR) in
order to determine if the marked hypertrophy of the right atria resulted in compromised myocardial perfusion. Myocardial blood
flow (ml/min/gm) was measured with radiolabeled microspheres in eight dogs with TR during rest, moderate exercise (5 dogs),
and infusion of adenosine (1 mg/kg/min), an index of minimal vascular resistance. Similar measurements were obtained in eight
normal dogs. In TR, the ratio of right atrium (RA) and right ventricle (RV) to body weight was greater than in normal dogs,
77 % and 30 %, respectively. During rest, flow in RA appendage was less than in nonappendage region in the normal dogs; no
differences were noted in TR dogs, indicating an augmented hemodynamic role of the appendage in TR. Both RA and RV blood flow
was greater in TR during rest but no other differences in flow were found between the two groups. Minimum vascular resistance
in RV but not RA was slightly increased in TR versus normal. During marked myocyte hypertrophy, the vasculature of RA develops
sufficiently to provide the same flow capacity as in the normal heart.
Received: 11 June 1997, Returned for revision: 15 July 1997, Revision received: 11 August 1997, Accepted: 7 September 1997 相似文献
80.
The purpose of this study was to assess, in subjects with low back pain, the changes and their permanence in muscular performance after a 3 month progressive physical exercise program. Ninety subjects with chronic low back pain participated in the study. The study design was controlled and it was carried out in three groups: intensive training, home exercise, and control group. Isometric and dynamic muscle strength of the trunk and lower limb were measured, at the beginning of the study and after the 3 months exercise program, and then during each of the follow-up sessions. The Oswestry Index and back pain intensity were also determined. Both exercise groups received benefit from the progressive exercise program. Their muscular performance improved and their back pain intensity decreased significantly. Among the home exercise group, the Oswestry Index also changed positively. The results demonstrate that the home exercise program could be as effective as the intensive training program in increasing muscle strength, as well as decreasing back pain and functional disability among low back pain patients with mild functional limitations. 相似文献