全文获取类型
收费全文 | 3641篇 |
免费 | 216篇 |
国内免费 | 67篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 87篇 |
妇产科学 | 22篇 |
基础医学 | 470篇 |
口腔科学 | 66篇 |
临床医学 | 511篇 |
内科学 | 343篇 |
皮肤病学 | 26篇 |
神经病学 | 417篇 |
特种医学 | 135篇 |
外科学 | 612篇 |
综合类 | 395篇 |
预防医学 | 107篇 |
眼科学 | 285篇 |
药学 | 222篇 |
3篇 | |
中国医学 | 162篇 |
肿瘤学 | 19篇 |
出版年
2023年 | 28篇 |
2022年 | 53篇 |
2021年 | 140篇 |
2020年 | 94篇 |
2019年 | 78篇 |
2018年 | 96篇 |
2017年 | 98篇 |
2016年 | 106篇 |
2015年 | 103篇 |
2014年 | 212篇 |
2013年 | 203篇 |
2012年 | 189篇 |
2011年 | 190篇 |
2010年 | 167篇 |
2009年 | 162篇 |
2008年 | 161篇 |
2007年 | 166篇 |
2006年 | 152篇 |
2005年 | 147篇 |
2004年 | 104篇 |
2003年 | 101篇 |
2002年 | 84篇 |
2001年 | 74篇 |
2000年 | 70篇 |
1999年 | 54篇 |
1998年 | 57篇 |
1997年 | 51篇 |
1996年 | 58篇 |
1995年 | 64篇 |
1994年 | 58篇 |
1993年 | 49篇 |
1992年 | 40篇 |
1991年 | 39篇 |
1990年 | 36篇 |
1989年 | 32篇 |
1988年 | 34篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 39篇 |
1984年 | 39篇 |
1983年 | 23篇 |
1982年 | 24篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 16篇 |
1976年 | 18篇 |
1975年 | 12篇 |
1972年 | 9篇 |
排序方式: 共有3924条查询结果,搜索用时 31 毫秒
71.
You-Hung Cheng Wei-Chun Lee Yi-Feng Tsai Hsuan-Kai Kao Wen-E Yang Chia-Hsieh Chang 《Journal of children's orthopaedics》2021,15(2):106
PurposeThis study aimed to compare the efficacy of decreasing leg-length discrepancy (LLD) and postoperative complications between tension band plates (TBP) and percutaneous transphyseal screws (PETS).MethodsThis retrospective study reviewed LLD patients who underwent temporary epiphysiodesis at the distal femur and/or proximal tibia from 2010 to 2017 (minimum two years follow-up). Efficacy of decreasing LLD was assessed one and two years postoperatively. Complications were classified with the modified Clavien-Dindo-Sink complication classification system. Knee deformities were assessed by percentile and zone of mechanical axis across the tibial plateau.ResultsIn total, 53 patients (25 boys, 28 girls) underwent temporary epiphysiodesis (mean age, 11.4 years). The efficacy of decreasing LLD at two years between the TBP (n = 38) and PETS (n = 15) groups was comparable. Seven grade III complications were recorded in six TBP patients and in one PETS patient who underwent revision surgeries for knee deformities and physis impingement. Four grade I and two grade II complications occurred in the TBP group. The mechanical axis of the leg shifted laterally in the PETS group and medially in the TBP groups (+7.1 percentile versus -4.2 percentile; p < 0.05). Shifting of the mechanical axis by two zones was noted medially in four TBP patients and laterally in two PETS patients.ConclusionMore implant-related complications and revision surgeries for angular deformities were associated with TBP. A tendency of varus and valgus deformity after epiphysiodesis using TBP and PETS was observed, respectively. Patients and families should be informed of the risks and regular postoperative follow-up is recommended.Level of evidenceLevel III 相似文献
72.
73.
液体表面张力系数及测量精度的分析 总被引:1,自引:0,他引:1
分子之间的相互作用产生分子力,阐述表面张力形成的基本原理。对表面张力系数的测量进行分析,讨论提高测量精度的方法。 相似文献
74.
A clinical comparison of indices of pulmonary gas exchange with changes in the inspired oxygen concentration 总被引:1,自引:0,他引:1
Several indices have been introduced as convenient alternatives to calculation of the physiological shunt fraction (Qs/QT) for the assessment of pulmonary gas exchange. These include: the arterial-alveolar oxygen tension ratio (a/APO2), the arterial oxygen tension-inspired oxygen concentration ratio (PaO2/FIO2), the respiratory index (RI), [A-a)DO2/PaO2) and the alveolar-arterial oxygen tension difference [A-a)Do2). These indices are in use clinically despite the fact that they may not accurately predict gas exchange in situations where FIO2, Qs/QT or arterial-venous oxygen content is changing. The clinical stability of each of these indices, relative to the behaviour of the physiological shunt, was therefore investigated prospectively in ten mechanically ventilated postoperative adults as FIO2 was varied from 0.30 to 1.00. None of the indices studied reliably reflected the behaviour of the physiological shunt. As FIO2 was increased incrementally from 0.30 to 1.00, 42 to 55 per cent of the measured changes in these indices were opposite in direction to the corresponding changes in the physiological shunt. The maximum magnitudes of the opposite changes were substantial; 24 and 22 per cent for the a/APO2 and PaO2/FIO2 ratio respectively, 67 per cent for the RI and 101 per cent for the (A-a)DO2. We conclude that the use of any of these indices for clinical assessment of a patient's gas exchange defect when FIO2 is varying can be substantially misleading. 相似文献
75.
Shuzo Oshita Yoshiki Fujiwara Hisashi Tamura Takefumi Sakabe Hiroshi Takeshita 《Journal canadien d'anesthésie》1994,41(6):534-541
To gain a better understanding of the direct actions of halothane on myocardial function in ischaemia, we studied the effects
of increasing extracellular potassium concentration and decreasing extracellular pH (acidosis), alone or in combination with
halothane, on the contractile force and resting tension in isolated atria. Guinea pig left atria were superfused with Tyrode’s
solution and stimulated at 1 Hz. Isometric contractile force and resting tension were measured using a force displacement
transducer. Perfusate potassium concentrations were increased from 5.4 mmol · L−1 to either 8.1 mmol · L−1 or 10.8 mmol · L−1 by adding KCl to the standard Tyrode’s solution, and its pH was decreased from 7.4 to either 7.0 or 6.5 by decreasing bicarbonate.
In standard Tyrode’s solution (potassium 5.4 mmol · L−1, pH 7.4), halothane 0.5–2% reduced contractile force in a dose-dependent manner (P < 0.05); the effective concentration of
halothane for 50% inhibition of contractile force (IC50) was 1.3%. Both increasing extracellular potassium and decreasing extracellular pH decreased the contractile force in a potassium-or
pH-dependent fashion. The negative inotropism of halothane (1%) was not altered by increasing potassium concentrations, whereas
1% halothane caused a greater decrease in contractile force at pH 6.5 than at pH 7.4. Halothane (1%) enhanced the acidosis
(pH 6.5)-induced increases in resting tension. Arrhythmias were produced in one of eight preparations during acidosis, while
four of eight preparations demonstrated arrhythmias during acidosis in the presence of halothane. These data suggest that
acidosis and halothane may have a synergistic interaction on the contractile force and resting tension of the atria. The increase
in resting tension observed during acidosis/ halothane conditions suggests than an increase in cytosolic calcium is associated
with these synergistic interactions between acidosis and halothane.
Pour mieux comprendre l’action direct de l’halothane sur la fonction myocardique pendant l’ischémie, nous avons étudié les
effets de l’augmentation du potassium extracellulaire et de la diminution du pH extracellulaire (acidose), seuls ou en association
avec l’halothane, sur la force contractile et la tension de repos d’oreillettes isolées. Des oreillettes gauches de cobaye
furent perfusées avec une solution de Tyrode et stimulées à 1 Hz. La force contractile isométrique et la tension de repos
ont été mesurées avec un transducteur de force de déplacement. Les concentrations de potassium perfusées ont été augmentées
de 5,4 mmol · L−1 à 8,1 mmol · L−1 ou à 10,8 mmol · L−1 par l’ajout de KCl à la solution standard de Tyrode, et son pH abaissé de 7,4 à 7,0 ou 6,5 par baisse des bicarbonates. Avec
la solution standard de Tyrode (potassium 5,4 mmol · L−1, pH 7,4), l’halothane (0.5–2%) diminue la force contractile proportionnellement à la dose (P < 0,05); la concentration efficace
d’halothane requise pour produire une inhibition de 50% de la force contractile (IC5O) a été de 1,3%. L’augmentation du potassium extracellulaire et la diminution du pH extracellulaire réduisent toutes les deux
la force contractile proportionnellement au potassium ou au pH. L’inotropisme négatif de l’halothane (1%) n’est pas modifié
par l’augmentation de la concentration de potassium alors que l’halothane produit une diminution plus importante de la force
contractile à un pH de 6,5 que de 7,4. L’halothane (1%) exagère l’augmentation de la tension de repos induite par l’acidose
(pH 6,5). Des arrythmies sont apparues sur une des huit préparations pendant l’acidose en présence d’halothane. Ces données
suggèrent que l’acidose et l’halothane pourraient avoir une activité synergique sur le force contractile et la tension de
repos des oreillettes. L’augmentation de la tension de repos observée pendant l’acidose combinée à l’halothane suggère l’association
d’une augmentation du calcium cytosolique avec des interactions synergiques entre l’acidose et l’halothane. 相似文献
76.
McCallion Orla N. M. Taylor Kevin M. G. Thomas Marian Taylor Anthony J. 《Pharmaceutical research》1995,12(11):1682-1688
Purpose. Empirical formulae relate the mean size of primary droplets from jet and ultrasonic nebulizers to a fluid's physicochemical properties. Although the size selective filtering effects of baffling and evaporation may modify the secondary aerosol produced, this research sought to evaluate whether viscosity and surface tension of nebulized fluids influenced the aerosol's size and output characteristics.
Methods. Fluid systems of different surface tension and viscosity (glycerol and propylene glycol solutions [10–50% (v/v)] and a range of silicone fluids [200/0.65 cs– l00cs]) were nebulized in three jet and two ultrasonic nebulizers. Secondary aerosol characteristics were measured with a Malvern 2600C laser diffraction sizer and the nebulization times, residual volumes and percentage outputs were determined.
Results. While the droplet size appeared to be inversely proportional to viscosity for jet nebulizers, it was directly proportional to viscosity for ultrasonic nebulizers. Although fluid systems with lower surface tensions generally produced slightly smaller MMDs, the relationship between surface tension and droplet size was complex. The more viscous fluids required longer nebulization times and were associated with increased residual amounts (lower outputs). The ultrasonic nebulizers did not effectively, and were on occasion unable to, nebulize the more viscous fluids.
Conclusions. It follows that there are cut-off values for viscosity and/or surface tension above or below which ultrasonic devices fail to operate. Moreover, jet nebulizers generated an aerosol with an optimum respirable output from median-viscosity fluids. 相似文献
77.
Jean -Henri Gaudy Marielle Quignon Atos Jean -François Sicard Raymond Maneglia 《Journal canadien d'anesthésie》1995,42(3):249-255
Certains patients atteints de paralysie diaphragmatique ou de dysfonctionnement diaphragmatique maintiennent leur ventilation par la mise en jeu d’autres muscles que le diaphragme. L’anesthésie, modifiant le fonctionnement de ces muscles, représente un risque potentiel chez ces patients. Afin d’évaluer ce risque, nous avons étudié les effets de l’halothane sur la ventilation et sur les gaz du sang artériel sur un modèle de paralysie diaphragmatique bilatérale, le rat phrénicectomisé. L’étude a été réalisée sur 43 rats. L’efficacité de la phrénicectomie a été contrôlée par l’observation directe, après laparotomie. La laparotomie n’entraine pas de modification des gaz du sang. Chez 23 rats, une laparotomie a été effectuée et une artère carotide a été cathétérisée. Chez 11 rats témoins, les nerfs phréniques ont été abordés, sans être sectionnés. Chez 12 rats, les phréniques ont été sectionnés. La ventilation a été mesurée par une technique pléthysmographique, chez les rats éveillés, avant et après l’opération, puis chez les mêmes rats anesthésiés avec 1,1%, d’halothane inspiré. Les gaz du sang ont été mesurés après l’opération chez les rats éveillés, puis anesthésiés. Chez les 23 rats opérés on observe, après l’opération, une diminution du poids et de la température centrale, plus importante chez les phrénicectomisés que chez les témoins. Chez les 11 rats témoins, après l’opération, la ventilation augmente, sans modification des gaz du sang. Chez ces rats, l’halothane provoque une diminution de la ventilation minute et de la PaO2 et une augmentation de la PaCO2. La phrénicectomie entraine chez les 12 rats, éveillés, une augmentation de la ventilation minute, une hypoxémie et une hypercapnie. Chez ces rats, l’halothane entraine le décès dans trois cas, une diminution de la ventilation minute et une hypercapnie et une hypoxémie importantes chez les neuf autres rats. Les modifications des gaz du sang sont plus importantes que chez les témoins anesthésiés. Chez le rat intact, l’halothane provoque des modifications des gaz du sang comparables à celles observées chez d’autres espèces et chez l’homme. La présente étude confirme les effets de l’halothane sur les muscles respiratoires autres que le diaphragme. Elle met en évidence le risque respiratoire majeur que l’anesthésie peut fair courir aux patients dont la ventilation est maintenue par d’autres muscles que le diaphragme. 相似文献
78.
目的 观察氯地滴眼液对家兔眼压及房角组织影响。方法 用60只家兔设实验和对照组,以含0.175%氯霉素和0.15%地塞米松的氯地跟液滴眼,每日4次,生理盐水对照。于1/2、1、2、3月测眼压后处死家兔以电镜观察房角组织变化。结果 眼压和房角组织结构与对照组无明显差异。结论 临床应用氯地眼液3月内是安全的。 相似文献
79.
人眼晶体悬韧带的张力测定 总被引:1,自引:0,他引:1
目的:进行人眼晶体悬韧带部位及其张力的测定。 方法:对26只离体尸眼进行测定。悬韧带的最大张力规定为:在其放松及最大伸张情况下,从睫状突到嵌入晶体前囊膜内的悬韧带的距离的差值。 结果:悬韧带在拉断之前平均能被拉长4.48±1.78mm,年轻组为5.33±1.19mm,老年组为2.17±0.70mm。无韧带区老年组为6.98±0.70mm,年轻组为7.66±0.42mm,平均为7.48±0.58mm。结论:悬韧带具有一定的张力,随着年龄的增长,悬韧带有向囊膜中心生长的趋势,无韧带区随年龄的增加而减小,悬韧带的张力随年龄的增加而减少。 相似文献
80.
Dr. I. Wessler C. Apel M. Garmsen A. Klein 《Journal of molecular medicine (Berlin, Germany)》1992,70(3-4):182-189
Summary The effects of nicotine receptor agonists on the release of [3H]acetylcholine from the phrenic nerve, the small intestine and the trachea were investigated to characterize neuronal nicotine receptors within the peripheral nervous system. Contraction of the indirectly-stimulated hemidiaphragm was recorded to investigate desensitization of the postsynaptic muscular nicotine receptors. Nicotine, cytisine, 1,1-dimethyl-4-phenylpiperazinium and 2-(4-aminophenyl)-ethyl-trimethyl-ammoniumiodide caused a concentration-dependent (0.1–30 M) increase in evoked [3H]acetylcholine release from the phrenic nerve, whereby bell-shaped concentration-response curves were obtained. The rank order of decreasing potency was: nicotine > cytisine > 1,1-dimethyl-4-phenylpiperazinium > 2-(4-aminophenyl)-ethyl-trimethyl-ammoniumiodide. The presynaptic effects of nicotine depended strongly on the exposure time: facilitation occurred after a short 20 s exposure and inhibition after a 3 min exposure, whereas nicotine no longer affected evoked [3H]acetylcholine release after a 15 min exposure. Pre-exposure (40 min) of the phrenic nerve to 0.3 M nicotine prevented any subsequent modulatory effect of a high nicotine concentration. In contrast, the contraction of the indirectly-stimulated hemidiaphragm remained unaffected in the presence of 0.3–30 M nicotine, but a concentration of 1 mM nicotine abolished skeletal muscle contraction. Nicotine (10 M) produced a substantial release of [3H]acetylcholine in the small intestine but not in the isolated trachea. The present experiments show presynaptic nicotine receptors at the phrenic nerve, which, under appropriate conditions, can mediate facilitation of evoked transmitter release. These neuronal receptors appear more sensitive to desensitizing conditions than the postsynaptic muscular nicotine receptors. Nicotine also mediates a transient release of acetylcholine in the myenteric plexus but not in the trachea, and as a consequence, applied nicotine preferentially activates smooth muscle activity in the intestine.Abbreviations DMPP
1,1-dimethyl-4-phenylpiperazinium
- PAPETA
2-(4-aminophenyl)-ethyl-trimethylammoniumiodiderine of [3H]acetylcholine release 相似文献