全文获取类型
收费全文 | 1885篇 |
免费 | 113篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 80篇 |
妇产科学 | 27篇 |
基础医学 | 291篇 |
口腔科学 | 33篇 |
临床医学 | 193篇 |
内科学 | 329篇 |
皮肤病学 | 33篇 |
神经病学 | 168篇 |
特种医学 | 285篇 |
外科学 | 172篇 |
综合类 | 38篇 |
预防医学 | 118篇 |
眼科学 | 19篇 |
药学 | 110篇 |
中国医学 | 1篇 |
肿瘤学 | 91篇 |
出版年
2022年 | 12篇 |
2021年 | 36篇 |
2020年 | 18篇 |
2019年 | 28篇 |
2018年 | 34篇 |
2017年 | 24篇 |
2016年 | 26篇 |
2015年 | 43篇 |
2014年 | 39篇 |
2013年 | 59篇 |
2012年 | 77篇 |
2011年 | 80篇 |
2010年 | 81篇 |
2009年 | 76篇 |
2008年 | 69篇 |
2007年 | 76篇 |
2006年 | 77篇 |
2005年 | 94篇 |
2004年 | 62篇 |
2003年 | 55篇 |
2002年 | 55篇 |
2001年 | 63篇 |
2000年 | 46篇 |
1999年 | 38篇 |
1998年 | 61篇 |
1997年 | 53篇 |
1996年 | 65篇 |
1995年 | 45篇 |
1994年 | 48篇 |
1993年 | 44篇 |
1992年 | 22篇 |
1991年 | 29篇 |
1990年 | 27篇 |
1989年 | 40篇 |
1988年 | 60篇 |
1987年 | 27篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 7篇 |
1976年 | 20篇 |
1975年 | 6篇 |
1974年 | 11篇 |
1972年 | 7篇 |
排序方式: 共有2035条查询结果,搜索用时 0 毫秒
101.
A generally accepted grading system for patients suffering from chronic hydrocephalus has not been established yet. Therefore we designed a new grading system, which focuses on five symptom categories: gait disturbances, mental disorder, incontinence, headache, dizziness. For each category clearly circumscribed degrees of handicaps are defined. For each degree a value between 0-6 points is assigned in concordance to the severity of handicap. To get a generally accepted validation of the obstruction, the assigned values were oriented on the values provided in Germany to evaluate the degree of obstruction for insurances.[nl]In contrast to the established gradings of Stein and Langfitt and the Black Rating Scale our grading allows a more exact acquisition of the clinical presentation of a patient. Our experiences with the grading seemingly indicate also, that it is reliable. Because the grading allows an incorporation of measurable data such as psychometric analysis or gait analysis, our grading is useful as well for everydays' practice as for scientific purpose. 相似文献
102.
Diffusion and perfusion MRI for the localisation of epileptogenic foci in drug-resistant epilepsy 总被引:3,自引:1,他引:2
Heiniger P el-Koussy M Schindler K Lövblad KO Kiefer C Oswald H Wissmeyer M Mariani L Donati F Schroth G Weder B 《Neuroradiology》2002,44(6):475-480
Drug-resistant epilepsy is an important clinical challenge, both diagnostically and therapeutically. More and more surgical options are being considered, but precise presurgical assessment is necessary. We prospectively studied eight patients with drug-resistant epilepsy, who underwent clinical examination, single photon emission computed tomography (SPECT) and interictal MRI, including diffusion- and perfusion-weighted echoplanar sequences. Lesions suspected on SPECT of being epileptogenic showed mild hypoperfusion, while the diffusion-weighted MRI (DWI) revealed increased apparent diffusion coefficients relative to the other side. However, these abnormalities were not visible on the corresponding maps. We showed that DWI and perfusion-weighted MRI could be used confirm the characteristics and site of an epileptogenic area in patients with drug-resistant epilepsy. 相似文献
103.
Leonhard C Müller M Hickey WF Ringelstein EB Kiefer R 《The European journal of neuroscience》2002,16(9):1654-1660
Resident macrophages of the peripheral nervous system have recently been shown to respond rapidly to Wallerian degeneration before the influx of blood-derived macrophages. Because resident endoneurial macrophages are slowly but incompletely exchanged from the blood within 3 months, they could potentially comprise a heterogenous cell population consisting of long-term resident cells and more mobile cells undergoing turnover. We used bone marrow chimeric mice created by transplanting bone marrow from green fluorescent protein-transgenic mice into irradiated wildtype recipients to selectively analyse the response of these two resident macrophage populations to Wallerian degeneration in sciatic nerve explant cultures. In such nerves, recently immigrated macrophages exhibit green fluorescence whereas long-term resident macrophages do not. Studies in cultures from wildtype controls revealed rapid morphological changes of resident macrophages towards a bloated phenotype, a proliferative response resulting in a 3.7-fold increase of macrophage numbers over 2 weeks, and phagocytosis of myelin basic protein-immunoreactive myelin debris. When chimeric mice were analysed, both populations of resident endoneurial macrophages participated in morphological transformation, proliferation and phagocytosis. Quantitative studies revealed a stronger proliferative and phagocytic response in long-term resident endoneurial macrophages compared with recently immigrated macrophages. Our results point towards subtle, but not principal, differences between the two macrophage populations, which might indicate different stages of macrophage differentiation rather than the existence of entirely distinct endoneurial macrophage populations. The results further underline the versatility of resident endoneurial macrophages following peripheral nerve injury, which is reminiscent of the lesion response of microglial cells within the brain. 相似文献
104.
The authors present a newly designed device for ultrasonic guidance of neuroendoscopic procedures. It consists of a puncture adapter that attaches to a rigid endoscope having an outer diameter of 6 mm and is mounted on a small, bayonet-shaped ultrasound probe. This adapter directs the movement of the endoscope precisely within the ultrasonic field of view. The targeted region is identified by transdural insonation via an enlarged single burr-hole approach, and the endoscope is tracked in real time throughout its approach to the target. The procedure has been performed in 10 patients: endoscopic ventriculocystostomy in four cases; removal of a colloid cyst of the third ventricle in two cases; and intraventricular tumor biopsy, intraventricular tumor resection, third ventriculostomy, and removal of an intraventricular hematoma in one case each. The endoscope was depicted on ultrasonograms as a hyperechoic line without disturbing echoes and, consequently, the target (cyst, ventricle, or tumor) was safely identified in all but one case, in which intraventricular air hid a colloid cyst in the foramen of Monro. The method presented by the authors proved to be very effective in the guidance and control of neuroendoscopic procedures. Combining this method with image guidance is recommended to define the entry point of the endoscope precisely. 相似文献
105.
Julia C Wessel Magdalena Matyja Michael Neugebauer Heiko Kiefer Thomas Daldrup Fuad A Tarbah Horst Weber 《European journal of pharmaceutical sciences》2006,28(1-2):15-25
Metamizol (dipyrone, 1), a widely used drug with effective analgesic and antispasmodic properties, shows severe side effects like agranulocytosis and anaphylactic shock reactions, the reasons of which are not known until today. After oral administration 1 is completely metabolized. All hitherto known metabolites have an intact pyrazolinone ring structure like the parent compound and are completely extractable from urine with polar organic solvents. However, only a fractional amount of the applied dosage can be recovered by this procedure. To clarify the reason of this deficit of unknown metabolites we followed the hypothesis of oxidative rupture of the heterocyclic ring during metabolism of 1. On the basis of former in vitro results we now were able to identify in quality three oxalic acid derivatives and one acetic acid phenylhydrazide as new metabolites of metamizol in the allantoic fluid (AF) of incubated hen's eggs as well as in human urine by means of GC-MS analysis and comparison with unequivocally synthesized authentic reference compounds. Whereas the oxamazide 7, the phenylhydrazide 8 and N-methyloxamic acid 9 are only present in trace concentrations and therefore cannot account for the deficit in the balance of metabolites, the oxalic acid monohydrazide 11 seems to be excreted in higher amount. But quantitative determination of this new metabolite would be required to answer the open questions concerning the biotransformation of metamizol and thereby to detect new facts about mode of action and side effects of this drug. 相似文献
106.
O. Adunka J. Kiefer M.H. Unkelbach A. Radeloff W. Gstoettner 《Clinical otolaryngology》2005,30(2):121-127
Objectives: Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Design: Human temporal bone study with histological and radiological evaluation. Setting: Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Main outcome measures: Cochlear trauma and intracochlear positions. Results: All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Conclusions: Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing. 相似文献
107.
Event-related brain potentials (ERPs) were used to investigate the neurophysiological correlates of conscious and unconscious semantic processing. Masked words, which do not enter consciousness, as well as visible words, were shown to modulate the N400 ERP potential to subsequently presented, meaningfully related target words. The N400 is known as an electrophysiological index of semantic processing. However, for unconsciously perceived words semantic brain activation decays fast within 200 ms, but increases with time for consciously perceived words. Thus, conscious and unconscious semantic activation involves similar brain areas, but both forms of processes exhibit distinct, qualitatively different time courses. 相似文献
108.
109.
目的:研究胰岛素样生长因子I(IGF I)和人绒毛膜促性腺激素(hCG)对成年大鼠睾丸Leydig细胞中葡萄糖转运蛋白(GLUT)基因表达的影响,为进一步探讨Leydig细胞中睾酮的合成、分泌与葡萄糖代谢的关系提供依据。方法:采用改良的Klinefelter方法从成年大鼠睾丸中分离获得Leydig细胞;用反转录聚合酶链技术检测IGF I和hCG对原代培养的Leydig细胞中GLUT基因表达的调控作用。结果:分离得到纯度为98%的大鼠Leydig细胞,并与对照组比较,hCG可显著增加Leydig细胞中GLUT8基因mRNA的表达水平(P<0.001),且此作用具有剂量依赖性与时效性。当在试验组细胞中单独加入IGF I或IGF I和hCG作用于细胞后,发现IGF I(100ng mL)可显著增加Leydig细胞中GLUT8基因mRNA的表达(P<0.01),也可与hCG协同作用显著提高GLUT8基因的mRNA表达,该结果与IGF I(100ng mL)和hCG(10ng mL)能协同作用极显著增加睾酮合成水平(P<0.001)的结果是相吻合的。在大鼠Leydig细胞中,无论10ng mL或100ng mL还是两者同时作用于细胞,都不能影响GLUT1和GLUT3基因的mRNA水平。结论:在成年大鼠Leydig细胞中,IGF I和hCG对细胞中的GLUT8基因表达的调节作用具有特异性,其协同作用能显著提高细胞中GLUT8基因mRNA水平,增强细胞摄取葡萄糖的能力,给细胞提供更多的代谢能源,最终增加Leydig细胞睾酮的合成与分泌。 相似文献
110.