全文获取类型
收费全文 | 5912篇 |
免费 | 308篇 |
国内免费 | 122篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 99篇 |
妇产科学 | 35篇 |
基础医学 | 1466篇 |
口腔科学 | 610篇 |
临床医学 | 517篇 |
内科学 | 609篇 |
皮肤病学 | 13篇 |
神经病学 | 478篇 |
特种医学 | 381篇 |
外科学 | 732篇 |
综合类 | 432篇 |
预防医学 | 208篇 |
眼科学 | 180篇 |
药学 | 295篇 |
1篇 | |
中国医学 | 130篇 |
肿瘤学 | 81篇 |
出版年
2024年 | 19篇 |
2023年 | 76篇 |
2022年 | 181篇 |
2021年 | 208篇 |
2020年 | 167篇 |
2019年 | 156篇 |
2018年 | 166篇 |
2017年 | 166篇 |
2016年 | 152篇 |
2015年 | 138篇 |
2014年 | 279篇 |
2013年 | 292篇 |
2012年 | 206篇 |
2011年 | 292篇 |
2010年 | 204篇 |
2009年 | 263篇 |
2008年 | 272篇 |
2007年 | 256篇 |
2006年 | 222篇 |
2005年 | 201篇 |
2004年 | 191篇 |
2003年 | 166篇 |
2002年 | 137篇 |
2001年 | 125篇 |
2000年 | 127篇 |
1999年 | 132篇 |
1998年 | 112篇 |
1997年 | 102篇 |
1996年 | 98篇 |
1995年 | 108篇 |
1994年 | 73篇 |
1993年 | 80篇 |
1992年 | 81篇 |
1991年 | 74篇 |
1990年 | 79篇 |
1989年 | 75篇 |
1988年 | 70篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 58篇 |
1984年 | 51篇 |
1983年 | 37篇 |
1982年 | 46篇 |
1981年 | 50篇 |
1980年 | 50篇 |
1979年 | 29篇 |
1978年 | 35篇 |
1977年 | 26篇 |
1976年 | 32篇 |
1975年 | 14篇 |
排序方式: 共有6342条查询结果,搜索用时 15 毫秒
11.
12.
Alberto Rivero Luis Crovetto Lidia Lopez Ricardo Maselli Martín Nogus 《Muscle & nerve》1995,18(9):943-947
We performed single fiber electromyography (SFEMG) in the superior rectus and levator palpebralis (SR-LP) muscles of 17 patients with pure ocular myasthenia gravis (MG) and 9 controls. Thirteen patients were also assessed with SFEMG in the orbicularis oculi (OO) muscle. All the MG patients but none of the control subjects showed abnormal SFEMG jitter in the SR-LP muscles. On the other hand, only 62% of the MG patients had abnormal SFEMG jitter in the OO muscle. The procedure was well tolerated by the patients, and complications were minor. We conclude that SFEMG of the SR–LP muscles is a safe and highly sensitive technique for the diagnosis of ocular MG. © 1995 John Wiley & Sons, Inc. 相似文献
13.
Ryo Suzuki M.D. Shunsaku Kobayashi 《Documenta ophthalmologica. Advances in ophthalmology》1988,70(4):293-300
Using tension-recording methods, we compared the effects of acetylcholine (Ach) and carbachol on the bovine iris sphincter. The isolated muscle strips were mounted in a 0.2 ml organ bath, through which Krebs solution at 36 °C flowed continuously. There was a tenthousandfold difference in potency between carbachol and Ach in this tissue. Neostigmine or eserine, acetylcholinesterase (AchE) inhibitors, produced a larger contraction of the muscle than did Ach. Ach-induced contractions were potentiated by low doses of anti-AchEs and were inhibited by atropine.This in vitro study suggests that Ach and/or endogenous chemical agents may be spontaneously released from tissues and that AchE activities in this tissue strongly inhibit or mask the Ach action, probably in order to protect the nerve terminals from released Ach. 相似文献
14.
采用细胞内微电极记录技术,同步观察了3,6-[二甲氨基]-二苯并碘因甲酸盐(IHC-64)对豚鼠心乳头肌细胞动作电位和收缩力的作用。50μmol/L IHC-64抑制心肌收缩力,而不影响快反应动作电位。增加IHC-64浓度,动作电位0相最大峰值(APA)、除极速率(dp/dt_(max))和复极50%和90%时程(APD_(50)、APD_(90))被明显抑制。IHC-64抑制慢反应动作电位,提高细胞外钙浓度可拮抗这种抑制。结果提示,IHC-64主要抑制慢Ca~(2+)内流,同时也部分抑制快Na~+内流,它可能是一种新型B类钙通道阻滞剂。 相似文献
15.
The purpose of this pilot study was to observe both relaxed and deep breathing patterns in a convenience sample to determine the incidence of normal versus faulty patterns of respiration. These observations were then combined with respondent answers to a survey on pain history to determine if there is any correlation between faulty breathing and musculo-skeletal pain patterns. If such a correlation can be made, then we propose that clinicians working with chronic pain patients may have improved outcomes if they address and correct faulty breathing patterns. Based on this study, it is suggested to include the evaluation and treatment of faulty respiration in the rehabilitation of chronic musculo-skeletal conditions, most notably cervical pain. 相似文献
16.
低氧及运动致大鼠骨骼肌形态学改变的实验研究 总被引:6,自引:0,他引:6
目的观察低氧及低氧复合运动时,大鼠体重及腓肠肌显微、超微结构的变化,旨在探讨低氧状态下适当运动对骨骼肌的影响。方法建立大鼠低氧及低氧复合运动模型,运用光镜及透射电镜观察大鼠腓肠肌显微、超微结构的变化。结果低氧复合运动组较低氧安静组大鼠体重差异有显著性意义(P<0.05)。低氧复合运动组骨骼肌结构正常,线粒体数量增加,骨骼肌纤维增粗,毛细血管增生。结论低氧复合适当的运动能够维持骨骼肌的正常形态,增强骨骼肌的有氧代谢,起到保护骨骼肌的作用,从而提高骨骼肌的低氧适应能力,促进低氧习服。 相似文献
17.
Mitsunori Murata M.D. 《Pediatrics international》1992,34(2):236-242
Since the end of the 2nd World War, Japan has seen quite rapid socioeconomical development. With this development the physical size of Japanese children has increased, but the final size, especially the stature, is still shorter than that of Americans or Europeans. Bone maturation velocities were compared among Japanese and Chinese children and adolescents aged 7 to 18 (in 1986) and English TW2-subjects, using the TW2 method. Asian children and adolescents may have a different tempo of skeletal maturation during pubertal growth from that of English children and adolescents. This, probably genetic, difference in the tempo of skeletal maturation, especially that of RUS, between Japanese and English during pubertal growth may be one of the main causes of the final difference in the stature of the two groups. 相似文献
18.
蝙蝠葛碱对奎尼丁诱发的豚鼠乳头肌早后去极化及触发活动的作用 总被引:4,自引:1,他引:3
用标准微电极技术观察了中药蝙蝠葛的有效成分蝙蝠葛碱对奎尼丁诱发的豚鼠乳头肌早后去极化及触发活动的影响. 结果表明,奎尼丁2 μmol·L-1能诱发豚鼠乳头肌早后去极化及触发活动,早后去极化的发生率为8/20, 幅值为13.4±2.6 mV, 起始电位为-42±5 mV, 触发活动的发生率为2/20. 蝙蝠葛碱20 μmol·L-1能明显抑制奎尼丁诱发的早后去极化及触发活动,早后去极化的发生率为4/20,幅值为7.3±1.1 mV,无触发活动. 结果提示蝙蝠葛碱具有抗早后去极化所致心律失常. 相似文献
19.
C. Veigel R. D. von Maydell K.R. Kress J. E. Molloy R. H. A. Fink 《Pflügers Archiv : European journal of physiology》1998,435(6):753-761
Recent atomic 3-D reconstructions of the acto-myosin interface suggest that electrostatic interactions are important in the
initial phase of cross-bridge formation. Earlier biochemical studies had also given strong evidence for the ionic strength
dependence of this step in the cross-bridge cycle. We have probed these interactions by altering the ionic strength (Γ/2)
of the medium mainly with K+, imidazole+ and EGTA2– to vary charge shielding. We examined the effect of ionic strength on the kinetics of rigor development at low Ca2+ (experimental temperature 18–22°C) in chemically skinned single fast-twitch fibres of mouse extensor digitorum longus (EDL)
muscle. On average the delay before rigor onset was 10 times longer, the maximum rate of rigor tension development was 10
times slower, the steady-state rigor tension was 3 times lower and the in-phase stiffness was 2 times lower at high (230 mM)
compared to low (60 mM) ionic strength. These results were modelled by calculating ATP depletion in the fibre due to diffusional
loss of ATP and acto-myosin Mg.ATPase activity. The difference in delay before rigor onset at low and high ionic strength
could be explained in our model by assuming a 15 times higher Mg.ATPase activity and a threefold increase in K
m in relaxing conditions at low ionic strength. Activation by Ca2+ induced at different time points before and during onset of rigor confirmed the calculated time course of ATP depletion.
We have also investigated ionic strength effects on rigor development with the activated troponin/tropomyosin complex. ATP
withdrawl at maximum activation by Ca2+ induced force transients which led into a ”high rigor” state. The peak forces of these force transients were very similar
at low and high ionic strength. The subsequent decrease in tension was only 10% slower and steady-state ”high rigor” tension
was reduced by only 27% at high compared to low ionic strength. Addition of 10 mM phosphate to lower cross-bridge attachment
strongly suppressed the transient increases in force at high ionic strength and reduced the steady-state rigor tension by
17%. A qualitatively similar but smaller effect of phosphate was observed at low ionic strength where steady-state rigor force
was reduced by 10%. The data presented in this study show a very strong effect of ionic strength on rigor development in relaxed
fibres whereas the ionic strength dependence of rigor development after thin filament activation was much less. The data confirm
the importance of electrostatic interactions in cross-bridge attachment and cross-bridge-attachment-induced activation of
thin filaments.
Received: 3 September 1997 / Received after revision and accepted: 12 December 1997 相似文献
20.
The purpose of the study was to compare the effect of voluntary pelvic floor muscle (PFM) contraction and vaginal electrical stimulation on urethral pressure. Twelve women with genuine stress incontinence, mean age 49.4 years (range 33–66) participated in the study. The urethral and bladder pressures were recorded simultaneously through a double-lumen 8 Ch catheter. The patients first performed three voluntary PFM contractions. Then two electrical stimulators, Conmax and Medicon MS 105, 50 Hz, were used in random order. A visual analog scale was used to measure pain and discomfort. Pain was reported to mean 6.8, SEM 0.64 (range 0.7–9.9) and mean 6.1, SEM 0.81 (range 0–9.1) with Conmax and Medicon MS 105, respectively. The mean paired difference in favor of voluntary contraction with Conmax was ?8.0, SD 6.7,P=0.0067, and with Medicon MS 105 it was ?12.2, SD 5.9,P=0.0022. The results demonstrated that voluntary PFM contraction increased urethral pressure significantly more than did vaginal electrical stimulation. 相似文献