全文获取类型
收费全文 | 8887篇 |
免费 | 500篇 |
国内免费 | 239篇 |
专业分类
耳鼻咽喉 | 158篇 |
儿科学 | 113篇 |
妇产科学 | 60篇 |
基础医学 | 1265篇 |
口腔科学 | 194篇 |
临床医学 | 737篇 |
内科学 | 858篇 |
皮肤病学 | 272篇 |
神经病学 | 1022篇 |
特种医学 | 194篇 |
外科学 | 831篇 |
综合类 | 876篇 |
预防医学 | 670篇 |
眼科学 | 167篇 |
药学 | 1353篇 |
中国医学 | 592篇 |
肿瘤学 | 264篇 |
出版年
2024年 | 43篇 |
2023年 | 105篇 |
2022年 | 265篇 |
2021年 | 359篇 |
2020年 | 294篇 |
2019年 | 218篇 |
2018年 | 186篇 |
2017年 | 203篇 |
2016年 | 251篇 |
2015年 | 298篇 |
2014年 | 477篇 |
2013年 | 616篇 |
2012年 | 404篇 |
2011年 | 488篇 |
2010年 | 426篇 |
2009年 | 421篇 |
2008年 | 463篇 |
2007年 | 427篇 |
2006年 | 453篇 |
2005年 | 376篇 |
2004年 | 333篇 |
2003年 | 322篇 |
2002年 | 238篇 |
2001年 | 216篇 |
2000年 | 183篇 |
1999年 | 184篇 |
1998年 | 154篇 |
1997年 | 136篇 |
1996年 | 105篇 |
1995年 | 114篇 |
1994年 | 89篇 |
1993年 | 71篇 |
1992年 | 88篇 |
1991年 | 65篇 |
1990年 | 75篇 |
1989年 | 50篇 |
1988年 | 54篇 |
1987年 | 56篇 |
1986年 | 38篇 |
1985年 | 44篇 |
1984年 | 31篇 |
1983年 | 25篇 |
1982年 | 41篇 |
1981年 | 26篇 |
1980年 | 25篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1974年 | 7篇 |
排序方式: 共有9626条查询结果,搜索用时 15 毫秒
101.
102.
Michael S. Glasgow Bernard T. Engel Burton C. D'Lugoff 《Journal of behavioral medicine》1988,11(5):435-446
Multiple daily, self-determined blood-pressure measurements were obtained from 254 hypertensive patients for 1 month. In an effort to establish a practical and reliable technique for estimating blood-pressure variability, standard deviations from three (at one time of day) or nine (throughout the day) successive self-determinations were compared with a reference value, taken to be the standard deviation for the entire month (252 determinations per subject). Neither the standard deviation of three measures taken on one occasion nor that of nine measures taken throughout the day correlated well with the reference value (average R3=.21 for SBP, .20 for DBP; average R9=.39 for SBP, .38 for DBP). However, when a sample consisting of 12 measures (taken three at a time, at the same time of day, weekly for 4 weeks) was used, the average correlation rose to .60 for SBP and .54 for DBP. Thus, it appears that 12 samples taken in this way provide a reliable estimate of the standard deviation for an entire month, and it is suggested that this sampling technique also would enhance the reliability of conclusions drawn from assessments of the prognostic value of blood-pressure variability. 相似文献
103.
G. N. Kryzhanovskii V. N. Grafova E. I. Danilova 《Bulletin of experimental biology and medicine》1977,83(5):607-611
With the aid of tetanus toxin, which disturbs various types of inhibition, generators of excitation were created in the left and right anterior horns of the lumbar spinal cord in rats. The regimes of activity of the generators differed: the left-sided generator, formed during the longer action of the toxin, in response to activation by trigger stimulation first produced tonic, and then intermittent activity, or individual spontaneous discharges, whereas the righ-sided generator produced only tonic activity. If one generator was blocked by glycine, the other continued to operate as before. Activation of one generator led to concomitant depression of the effects of the other. During separate activation of each generator, all the spinal and supraspinal motoneuron pools synchronously reproduced the character of activity of the generator functioning at that particular moment. The generator thus played the role of a determinant structure, determining the behavior of the system. The results are examined from the standpoint of the general concept of the role of determinant structures in the activity of the nervous system and the theory of generator mechanisms of neuropathological syndromes characterized by hyperactivity of systems.Laboratory of General Pathology of the Nervous System, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 5, pp. 515–519, May, 1977. 相似文献
104.
目的:观察睡眠剥夺(SD)后大鼠脑组织HSP70表达的变化及对超微结构的影响。方法:44只雄性SD大鼠随机分为11组,每组4只,免疫组织化学方法检测HSP70的表达,电镜观察海马超微结构的变化。结果:睡眠剥夺后12小时即可在大脑皮质及海马观察到HSP70阳性细胞,2—3天数量达到高峰,7天时明显下降。白天睡眠剥夺12小时(SDd12h)组HSP70阳性细胞数较夜晚睡眠剥夺12小时(SDn12h)组多(P〈0.05)。RS组大脑皮质HSP70阳性细胞数较白天睡眠剥夺1天(SDd1d)组减少(P〈0.05)。白天睡眠剥夺3天(SDd3d)海马出现超微结构改变,白天睡眠剥夺7天(SDd7d)后改变更加明显。结论:睡眠剥夺可影响大鼠脑组织HSP70表达及超微结构。 相似文献
105.
热休克蛋白70对离体心脏心肌间质的保护作用 总被引:2,自引:0,他引:2
目的探讨热休克蛋白70(HSP70)对大鼠离体心脏心肌间质的影响。方法Wistar大鼠16只,分为2组:对照组(C,n=8),腹腔注射生理盐水0.4ml,24h后取离体心脏灌注HTK心脏保护液,4℃保存3h后建立Langendorff灌注模型,灌注KH液2h;实验组(E,n=8),腹腔注射重酒石酸去甲肾上腺素,24h后取离体心脏,方法同对照组。以心肌细胞中HSP70含量、血流动力学指标、心肌组织羟脯氨酸(HP)、内皮索(ET)含量和心肌超微结构等作为观察指标。结果HSP70含量E组与C组比较明显增高;E组心功能恢复方面优于C组(P〈0.05),HP含量优于C组(P〈0.01),ET含量低于C组(P〈0.01),心肌超微结构损伤较C组明显减轻。结论HSP
70对供心心肌间质具有保护作用。 相似文献
106.
Arngrímsson SA Petitt DS Borrani F Skinner KA Cureton KJ 《European journal of applied physiology》2004,92(4-5):524-532
To compare the effect of hyperthermia on maximal oxygen uptake (O2max) in men and women, O2max was measured in 11 male and 11 female runners under seven conditions involving various ambient temperatures (Ta at 50% RH) and preheating designed to manipulate the esophageal (Tes) and mean skin
temperatures at O2max. The conditions were: 25°C, no preheating (control); 25, 35, 40, and 45°C, with exercise-induced preheating by a 20-min walk at ~33% of control O2max; 45°C, no preheating; and 45°C, with passive preheating during which Tes and
were increased to the same degree as at the end of the 20-min walk at 45°C. Compared to O2max (l·min–1) in the control condition (4.52±0.46 in men, 3.01±0.45 in women), O2max in men and women was reduced with exercise-induced or passive preheating and increased Ta, ~4% at 35°C, ~9% at 40°C and ~18% at 45°C. Percentage reductions (7–36%) in physical performance (treadmill test time to exhaustion) were strongly related to reductions in O2max (r=0.82–0.84). The effects of hyperthermia on O2max and physical performance in men and women were almost identical. We conclude that men and women do not differ in their thermal responses to maximal exercise, or in the relationship of hyperthermia to reductions in O2max and physical performance at high temperature. Data are reported as mean (SD) unless otherwise stated. 相似文献
107.
Joachim Saloga Gideon Lack Kathrine Bradley Harald Renz Gary Larsen Donald Y. M. Leung Erwin W. Gelfand 《European journal of immunology》1994,24(12):3140-3147
We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive Vβ8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of Vβ8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization to OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the Vβ8 T cell population, they did reduce the proliferative response of Vβ8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive Vβ8 T cells. 相似文献
108.
Duncan Mitchell C. H. Wyndham A. R. Atkins A. J. Vermeulen H. S. Hofmeyr N. B. Strydom T. Hodgson 《Pflügers Archiv : European journal of physiology》1968,303(4):324-343
Summary Two nude resting men were exposed for two-hour periods to each of 25 dry environments, with air temperatures ranging between 12.8° C and 49.1° C and wind speeds between 0.67 m/sec and 4.94 m/sec. The mean radiant temperature of the surroundings was kept equal to the air temperature. Rates of radiant and convective heat exchange were measured directly, separately and continuously. The men had reached a thermal steady state after 105 min in the warm environments, but not in the cold environments. Graphs are presented to show the effect of ambient temperature and wind speed on the radiation and convection rates attained after 105 min, as well as on metabolic rate, sweat evaporation rate, rectal temperature and mean skin temperature. These graphs revealed some important aspects of the behaviour of man's thermal control system. In particular the physiological conductance increased with increasing ambient temperature and then saturated at an ambient temperature near 35° C. This saturation resulted in a constant difference between rectal temperature and mean skin temperature irrespective of the environmental conditions.Published with the permission of the Chamber of Mines of South Africa. 相似文献
109.
Da Costa CU Wantia N Kirschning CJ Busch DH Rodriguez N Wagner H Miethke T 《European journal of immunology》2004,34(10):2874-2884
Heat shock protein 60 (HSP60) from Chlamydia pneumoniae was described to trigger in vitro inflammatory and cytokine responses including TNF and IL-12p40. Although it can be found in atherosclerotic plaques of patients, the stimulatory potential of chlamydial and other HSP60 in vivo is unclear. We now report that chlamydial HSP60 fails to induce TNF expression in vivo, and significant serum levels of IL-12p40 are only found upon intraperitoneal injection of high doses of HSP60 or after intravenous application. Upon purification of chlamydial HSP60 with polymyxin B-agarose columns, its ability to induce TNF secretion in vitro is much reduced. However, purified chlamydial HSP60 causes increased serum levels of the CXC chemokines KC and MIP2 in vivo, as well as a strong accumulation of polymorphonuclear neutrophils (PMN) in the peritoneal cavity upon intraperitoneal challenge. With respect to PMN accumulation, chlamydial HSP60 is more potent than endotoxin or the CpG oligonucleotide 1668. The responses observed are completely abolished in Toll-like receptor (TLR)2/4-double-deficient mice, while single-deficient mice respond almost normally. Furthermore, KC induction and PMN accumulation are largely dependent on MyD88. In conclusion, HSP60 from C. pneumoniae triggers inflammatory responses in vivo that differ from responses induced by endotoxin or CpG oligonucleotides and are dependent on TLR2 and 4. 相似文献
110.
T. Angelone E. Filice A. M. Quintieri S. Imbrogno A. Recchia E. Pulerà C. Mannarino D. Pellegrino M. C. Cerra 《Acta physiologica (Oxford, England)》2008,193(3):229-239
Aims: Using a model of isolated and Langendorff‐perfused rat heart we analysed whether activation of β3‐adrenergic receptors (β3‐ARs) influences ventricular lusitropic performance. We also focused on the NOS/NO/cGMP/PKG cascade as the signal transduction mechanism. Methods: Hearts were treated with increasing concentrations (from 10?12 to 10?6 m ) of BRL37344, a selective β3‐AR agonist, and cardiac performance was evaluated by analysing both lusitropic parameters and coronary motility. Cardiac preparations were also perfused with BRL37344 in the presence of either isoproterenol (ISO) or nadolol, or pertussis toxin (PTx), or selective inhibitors of the NOS/NO/cGMP/PKG pathway. Results: BRL37344 caused a significant concentration‐dependent reduction in (LVdP/dt)min, a decrease in half time relaxation significant starting from 10?12 m , and an increase in (LVdP/dt)max/(LVdP/dt)min ratio (T/?t). BRL37344 abolished the ISO‐mediated positive lusitropism. β3‐AR‐dependent effects on relaxation were insensitive to β1/β2‐AR inhibition by nadolol (100 nm ), and were abolished by Gi/o protein inhibition by PTx (0.01 nm ). NO scavenging by haemoglobin (10 μm ), and nitric oxide synthase (NOS) inhibition by NG‐monomethyl‐l ‐arginine (10 μm ) revealed the involvement of NO signalling in BRL37344 response. Pre‐treatment with inhibitors of either soluble guanylate cyclase (ODQ; 10 μm ) or PKG (KT5823; 100 nm ) abolished β3‐AR‐dependent negative lusitropism. In contrast, anantin (10 nm ), an inhibitor of particulate guanylate cyclase, did not modify the effect of BRL37344 on relaxation. Conclusion: Taken together, our findings provide functional evidence for β3‐AR modulation of ventricular relaxation in the rat heart which involves PTx‐sensitive inhibitory Gi protein and occurs via an NO‐cGMP‐PKG cascade. Whether the effects of β3‐AR stimulation on lusitropism are beneficial or detrimental remains to be established. 相似文献