全文获取类型
收费全文 | 20443篇 |
免费 | 736篇 |
国内免费 | 202篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 614篇 |
妇产科学 | 105篇 |
基础医学 | 1914篇 |
口腔科学 | 26篇 |
临床医学 | 3699篇 |
内科学 | 6211篇 |
皮肤病学 | 35篇 |
神经病学 | 419篇 |
特种医学 | 948篇 |
外科学 | 2527篇 |
综合类 | 2371篇 |
预防医学 | 543篇 |
眼科学 | 4篇 |
药学 | 1298篇 |
7篇 | |
中国医学 | 351篇 |
肿瘤学 | 302篇 |
出版年
2023年 | 260篇 |
2022年 | 571篇 |
2021年 | 767篇 |
2020年 | 643篇 |
2019年 | 742篇 |
2018年 | 756篇 |
2017年 | 559篇 |
2016年 | 489篇 |
2015年 | 654篇 |
2014年 | 1495篇 |
2013年 | 1276篇 |
2012年 | 997篇 |
2011年 | 1163篇 |
2010年 | 977篇 |
2009年 | 1013篇 |
2008年 | 1060篇 |
2007年 | 971篇 |
2006年 | 893篇 |
2005年 | 688篇 |
2004年 | 579篇 |
2003年 | 475篇 |
2002年 | 399篇 |
2001年 | 300篇 |
2000年 | 304篇 |
1999年 | 256篇 |
1998年 | 189篇 |
1997年 | 212篇 |
1996年 | 210篇 |
1995年 | 181篇 |
1994年 | 178篇 |
1993年 | 155篇 |
1992年 | 134篇 |
1991年 | 124篇 |
1990年 | 105篇 |
1989年 | 90篇 |
1988年 | 117篇 |
1987年 | 93篇 |
1986年 | 73篇 |
1985年 | 120篇 |
1984年 | 160篇 |
1983年 | 87篇 |
1982年 | 107篇 |
1981年 | 94篇 |
1980年 | 101篇 |
1979年 | 79篇 |
1978年 | 59篇 |
1977年 | 72篇 |
1976年 | 79篇 |
1975年 | 73篇 |
1974年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Michael S. Yates C. Robin Hiley 《Pflügers Archiv : European journal of physiology》1979,379(2):219-222
The distribution of cardiac output was determined by 15 m radioactive microspheres in all the major organs of spontaneous, DOCA/NaCl and one kidney Goldblatt hypertensive rats and compared to normotensive Wistar rats. Although there were alterations in cardiac output distribution which were characteristic of each model of hypertension significant changes were common to all three were an increased distribution to skeletal muscle with decreases to the lungs, spleen and hepatosplanchnic tissues. The results suggest that alterations in peripheral resistance induced by hypertension are of unequal importance in the different vascular beds with certain vascular resistance changes occurring irrespective of the origin of the hypertension.Abbreviations used in this paper SHR
spontaneously hypertensive rats
- DOCA
deoxycorticosterone acetate
Supported by I.C.I. Pharmaceutical Ldt and the Mersey Regional Health Authority (Research Schemes No. 338). 相似文献
92.
Margaret O''Dougherty Gary G. Berntson Sarah T. Boysen Francis S. Wright Douglas Teske 《Psychophysiology》1988,25(3):305-315
Cardiac responses to non-signal stimuli and to signal stimuli in a vigilance task were examined in children born with congenital heart defects (CHD), and in normal and attention deficit disordered (ADD) subjects. Overall task performance was lower in subjects with heart defects and in the ADD group. Cardiac measures revealed that normal children displayed significantly larger heart rate deceleration to the target stimuli than did either of the clinical groups. Moreover, although no group differences were observed in the cardiac response to non-signal auditory stimuli, exaggerated heart rate deceleration was observed to vibrotactile stimuli in both the clinical groups. Regression analyses revealed that the magnitude of the cardiac response to somatosensory stimuli was predictive of task performance (both within and between subject groups), with larger responses associated with higher error rates and lower perceptual sensitivity. Results were suggestive of a predictive relationship between somatosensory reactivity and neuropsychological maturation. 相似文献
93.
M. E. Verberne A. C. Gittenberger-de Groot R. E. Poelmann 《Anatomy and embryology》1998,198(3):171-184
We were interested in the contribution of the cardiac neural crest to the complete anterior and posterior nerve plexus of
the chick heart. This includes the pathways by which these cardiac neural crest-derived neuronal precursors enter the heart.
As lineage techniques we used the traditional quail-chick chimera in combination with the newly introduced technique of retroviral
reporter gene transfer to premigratory cardiac neural crest cells. Retrovirally infected embryos (n=23) and quail-chick chimeras (n=19) between stages HH27 and 40, were immunohistochemically evaluated, using the lineage markers LacZ (retroviral reporter)
and QCPN (anti-quail nuclear marker), respectively and the neuronal differentiation markers HNK-1, RMO-270 and DO-170. Between
stages HH27 and 33, quail-derived and LacZ positive cells were situated around the arterial cardiac vagal branches at the
arterial pole, and vagal branches along the anterior cardinal veins and the sinal vagal branch at the venous pole. From stage
HH35 onward, QCPN/LacZ-positive cardiac ganglia were observed throughout the anterior and posterior plexus and were mainly
concentrated in the subepicardium near the distal ends of the arterial cardiac vagal branches and the sinal cardiac vagal
branch respectively. From stage HH36 both the anterior and posterior plexus contained a population of large cardiac ganglion
cells and a population of smaller cells along nerve branches as well as in the cardiac ganglia, which means that differentiation
starts in both plexus at the same time. Furthermore only nerve fiber connections between the anterior and posterior plexus
were observed. These results show that the cardiac neural crest contributes to the cardiac ganglion cells from both the entire
anterior and posterior plexus. Furthermore these results suggest that these precursor cells enter the arterial pole via the
arterial cardiac vagal branches and the venous pole via the sinal cardiac vagal branch without intermixing. Finally we show
that in addition to the cardiac ganglia, the cardiac neural crest contributes to small myocardial glia or undifferentiated
cells along nerve fibers, and some myocardial nerve fibers as well as nerve tissue in the adventitia of the large veins at
the venous pole and in the adventitia of the coronary arteries.
Accepted: 30 March 1998 相似文献
94.
D. Lang G. G. Belz R. Hofstetter U. Töllner G. von Bernuth 《Journal of molecular medicine (Berlin, Germany)》1976,54(8):389-390
Summary Serum digoxin concentration and half-life were radioimmunologically determined in 9 mature newborns after 7 days medication with digoxin. The newborns were in respiratory distress treated with continuous positive airway pressure or were suspected to have serious congenital heart disease. Loading dose was 26 µg/kg body weight intravenously and 35 µg/kg body weight orally, respectively. Maintenance dose corresponded to 1/8th of the digitalization dose twice daily.The serum digoxin level 12 h after the last dose varied between 1.4 and 2.5 ng/ml (mean 2.0 ng/ml, Sx=0.4). The serum half-life of digoxin varied between 21.7 and 42.4 h (mean 30.0 h, Sx=7.7). The mean serum half-life of digoxin of 30 h attained values found in adults without renal disease. This suggests that the serum digoxin levels of newborns which are usually higher if compared with those of adults result from higher digoxin doses per unit body weight and not from diminished digoxin elimination. 相似文献
95.
Previous studies demonstrated distinct cardiovascular patterns associated with threat and challenge appraisals for groups of participants. We extend these results by assessing whether appraisals continue to be associated with these cardiovascular response patterns within an individual as appraisals change. Participants completed four verbal mental arithmetic tasks for which they made appraisals before and after each task. Cardiac reactivity and total peripheral resistance (TPR) were calculated for the first and last minutes of each task, and the number of responses and percent correct were measured for each task. In line with our prediction, pretask appraisals were related to some task-related cardiac responses across the four tasks. In addition, task-related cardiovascular reactivity and behaviors both influenced appraisals following the task. Our findings suggest that an idiographic analysis of appraisals, cardiovascular physiology, and task-related behaviors provides a richer understanding of the appraisal process and reveals sex differences deserving further assessment. 相似文献
96.
The goal of this study was to investigate whether cruzipain, a Trypanosoma cruzi immunodominant antigen, was able to induce antibodies reactive to the cardiac M(2) muscarinic acetylcholine receptor (M(2) mAChR). Immunization with cruzipain that was devoid of enzyme activity triggered IgG antibodies against cardiac M(2) mAChR. By radioligand competition assay we proved that the anti-cruzipain IgG fraction, purified from serum, inhibited binding of the specific M(2) mAChR radioligand [(3)H]quinuclidinyl benzilate. We also demonstrated that anti-cruzipain IgG reacted against the second extracellular loop of the M(2) mAChR. The corresponding affinity-purified serum anti-M(2)e2 IgG (reacting against a synthetic peptide corresponding to this loop in humans) displayed agonist-like activity associated with specific M(2) mAChR activation - increase of cGMP, inositol phosphate accumulation and nitric oxide synthase activity - triggering a decrease in myocardial contractility. Moreover, the same IgG fraction decreased heart frequency, related to inhibition of adenylate cyclase activity. These results imply that cruzipain plays a role in the production of antibodies against M(2) mAChR, which have been related to the pathogenesis of dysautonomic syndrome described in Chagas' disease. 相似文献
97.
父母教养方式:EMBU的初步修订及其在神经症患者的应用 总被引:141,自引:20,他引:141
岳冬梅 《中国心理卫生杂志》1993,7(3):97-101
本文选取390名正常人为被试,对父母教养方式调查问卷 EMBU (Egna Minnen avBarndosnauppforstran) 通过主因素分析,项目分析进行了初步修订。修订后的问卷涉及父亲58个条目。母亲57个条目,并各自由六个和五个分量表组成。并对66名神经症患者和66名正常人进行了效度的实证考查。 相似文献
98.
Peter A. Shapiro Richard P. Sloan Emilia Bagiella J. Thomas Bigger JR. Jack M. Gorman 《Psychophysiology》1996,33(1):54-62
Heart rate reactivity to mental stress is substantially blunted early after heart transplantation, suggesting that the loss of neural modulation limits the cardiovascular response to mental stress. We tested whether reactivity to mental stress recovers during the first year after heart transplantation. Hemodynamic and respiratory responses to mental arithmetic challenge were studied in 20 heart transplant recipients 3, 6, and 12 months after surgery. A normal comparison group was studied at equivalent intervals. Heart rate reactivity to mental arithmetic was significantly reduced in the cardiac transplant group compared to the normal subjects. This effect persisted up to 1 year after transplantation. Heart period variability in the heart transplant recipients was minimal in all three-test sessions. The findings suggest that no functional reinnervation or other compensatory adaptation occurs up to 1 year after heart transplantation. 相似文献
99.
Richard J. Davidson Mark E. Horowitz Gary E. Schwartz David M. Goodman 《Psychophysiology》1981,18(1):36-41
Based upon suggestions that the two cerebral hemispheres may be differentially involved in the perception and regulation of autonomic activity, three studies were designed to explore differences in the relationship between left versus right hand finger tapping and the heartbeat. In each study, right-handed subjects were asked to tap with either their left versus right forefingers regularly at the rate of approximately once per second. When the time from the R-spike immediately preceding their tap to the tap was examined, a significant difference between the two hands was obtained in two of the studies, with the left hand tapping closer to the last R-spike compared with the right. A variety of additional conditions in the experiments suggest that this effect may depend upon tapping rhythmically. The implications of these findings for the differential role of the left and right hemispheres in the perception and regulation of cardiac activity are considered. 相似文献
100.
Norio Fukuda Hideaki Fujita Takashi Fujita Shin’ichi Ishiwata 《Pflügers Archiv : European journal of physiology》1996,433(1-2):1-8
Skinned fibres from bovine ventricles exhibited spontaneous tension oscillations when MgADP and inorganic phosphate (Pi)
were added to the solution bathing fibres in the relaxed state (ADP-SPOC). A similar type of oscillation was observed at intermediate
concentrations of free Ca2+ in the absence of MgADP and Pi (Ca-SPOC). To investigate the correlation between ADP-SPOC and Ca-SPOC, we constructed two-dimensional
state diagrams of cardiac muscle using different concentrations of Pi (0–20 mM) and free Ca2+ [pCa=around 5 (+Ca2+), pCa=5.15–6.9 and +EGTA (–Ca2+)], with varying concentrations of MgADP (0–10 mM), with 2 mM MgATP and 2 mM free Mg2+ maintaining ionic strength at 0.15±0.01 M, pH 7.0, 25 °C. The three-dimensional (pCa-Pi-MgADP) state diagram thus obtained
was divided into three regions, i.e. the contraction region in which tension oscillation was undetectable, the spontaneous
tension oscillation (SPOC) region and the relaxation region. We found that the regions of ADP-SPOC and Ca-SPOC were continuously
connected by a single oscillation region sandwiched between the contraction and relaxation regions. The state diagram, which
encompasses physiological conditions, shows that the probability of SPOC is higher in cardiac muscle than in skeletal muscle.
From these results, we suggest that, despite distinct ionic conditions, the molecular state of cross-bridges during SPOC is
common to both ADP-SPOC and Ca-SPOC.
Received 19 February 1996 / Received after revision: 16 July 1996 / Accepted: 14 August 1996 相似文献