全文获取类型
收费全文 | 3757篇 |
免费 | 172篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 136篇 |
妇产科学 | 85篇 |
基础医学 | 433篇 |
口腔科学 | 41篇 |
临床医学 | 360篇 |
内科学 | 667篇 |
皮肤病学 | 68篇 |
神经病学 | 271篇 |
特种医学 | 428篇 |
外科学 | 476篇 |
综合类 | 21篇 |
预防医学 | 132篇 |
眼科学 | 381篇 |
药学 | 200篇 |
肿瘤学 | 230篇 |
出版年
2022年 | 27篇 |
2021年 | 29篇 |
2020年 | 20篇 |
2019年 | 24篇 |
2018年 | 48篇 |
2017年 | 32篇 |
2016年 | 51篇 |
2015年 | 94篇 |
2014年 | 83篇 |
2013年 | 111篇 |
2012年 | 122篇 |
2011年 | 147篇 |
2010年 | 119篇 |
2009年 | 108篇 |
2008年 | 137篇 |
2007年 | 136篇 |
2006年 | 121篇 |
2005年 | 138篇 |
2004年 | 127篇 |
2003年 | 133篇 |
2002年 | 113篇 |
2001年 | 122篇 |
2000年 | 90篇 |
1999年 | 118篇 |
1998年 | 135篇 |
1997年 | 95篇 |
1996年 | 102篇 |
1995年 | 65篇 |
1994年 | 81篇 |
1993年 | 84篇 |
1992年 | 60篇 |
1991年 | 42篇 |
1990年 | 60篇 |
1989年 | 87篇 |
1988年 | 57篇 |
1987年 | 84篇 |
1986年 | 52篇 |
1985年 | 68篇 |
1984年 | 50篇 |
1983年 | 35篇 |
1982年 | 34篇 |
1981年 | 39篇 |
1980年 | 37篇 |
1979年 | 24篇 |
1978年 | 25篇 |
1977年 | 41篇 |
1976年 | 32篇 |
1975年 | 21篇 |
1974年 | 19篇 |
1927年 | 15篇 |
排序方式: 共有3943条查询结果,搜索用时 11 毫秒
21.
22.
B Holland R Kubale G Seitz 《R?ntgen-Bl?tter; Zeitschrift für R?ntgen-Technik und medizinisch-wissenschaftliche Photographie》1985,38(3):87-92
Adenoma sebaceum, also known as Pringle's tumour, is frequently associated with tuberous sclerosis (Bourneville's disease); if the lungs are involved, however, the clinical course is different from that of the "classical" type of the combination of these two diseases without lung involvement. The case record of a woman patient in whom the lung was affected, is presented with a brief discussion of the x-ray and pathological changes and their differential diagnosis. 相似文献
23.
Hans J. Seitz Wilhelm Krone Harald Wilke Wolfgang Tarnowski D. Carsten B. Dunkelmann A. Harneit 《Pflügers Archiv : European journal of physiology》1981,389(2):115-120
The effect of acute cold exposure on the concentration of glucagon in the blood was investigated in man and in intact and adrenalectomized rats.In man fasted overnight acute cold exposure, which caused a twofold increase in O2-consumption resulted in a rapid rise in plasma glucagon. The levels of insulin and blood glucose remained unaltered, while the concentration of serum free fatty acids and -hydroxybutyrate increased.In fasted intact rats acute cold exposure lead to similar effects. A close parallelism between the rise in plasma glucagon and the concentration of hepatic cycloAMP was observed. Adrenalectomy did not impair the cold induced rise in plasma glucagon and hepatic cycloAMP.It is concluded that acute cold exposure caused a rapid rise in the concentration of plasma glucagon leading to an increase in the concentration of hepatic cycloAMP, thus enhancing the rate of hepatic gluconeogenesis and ketogenesis. As these alterations were similar in the absence of glucocorticoids and medulla-derived catecholamines, it is suggested that glucagon may play a role in the metabolic adaptation to acute cold exposure. 相似文献
24.
Three small peptides with a typical cysteine-rich domain (TFF or P-domain) display a specific folding structure (trefoil); they are abundantly expressed on mucosal surfaces of normal and neoplastic gastrointestinal tissues. This epithelial location coincides with mucin secretion and, although not proven beyond doubt, this association is suggestive of their function in maintenance of surface integrity. Using normal colon epithelium, premalignant lesions and tumor samples and specific antibodies we studied expression of these peptides in colorectal carcinomas. RT PCR was performed to extend the sensitivity of the assays. While coexpression of pS2, hITF, MUC1 and MUC2 was demonstrated, MUC5 was absent and no simultaneous activity of pS2 and SML1 (as in gastric mucosa and carcinoma) was noted in rectal tumors. Actively transcribed and expressed cytokeratin 20 and GAPDH were used as experimental controls for immunostaining and RT-PCR, respectively. 相似文献
25.
Langenbucher A Seitz B Kus MM Naumann GO 《Investigative ophthalmology & visual science》1999,40(3):582-591
PURPOSE: To demonstrate a mathematical method for decomposition of discrete corneal topography height data into a set of Zernike polynomials and to demonstrate the clinical applicability of these computations in the postkeratoplasty cornea. METHODS: Fifty consecutive patients with either Fuchs' dystrophy (n = 20) or keratoconus (n = 30) were seen at 3 months, 6 months, and 1 year (before suture removal) and again after suture removal following nonmechanical trephination with the excimer laser. Patients were assessed using regular keratometry, corneal topography (TMS-1, simulated keratometry [SimK]), subjective refraction, and best-corrected visual acuity (VA) at each interval. A set of Zernike coefficients with radial degree 8 was calculated to fit two model surfaces: a complete representation (TOTAL) and a representation with parabolic terms only to define an approximate spherocylindrical surface (PARABOLIC). The root mean square error (RMS) was calculated comparing the corneal raw height data with TOTAL (TOTALRMS) and PARABOLIC (PARABOLICRMS). The cylinder of subjective refraction was correlated with the keratometric readings, the SimK, and the respective Zernike parameter. Visual acuity was correlated with the tilt components of the Zernike expansion. RESULTS: The measured corneal surface could be approximated by the composed surface 1 with TOTALRMS < or = 1.93 microm and by surface 2 with PARABOLICRMS < or = 3.66 microm. Mean keratometric reading after suture removal was 2.8+/-0.6 D. At all follow-up examinations, the SimK yielded higher values, whereas the keratometric reading and the refractive cylinder yielded lower values than the respective Zernike parameter. The correlation of the Zernike representation and the refractive cylinder (P = 0.02 at 3 months, P = 0.05 at 6 months and at 1 year, and P = 0.01 after suture removal) was much better than the correlation of the SimK and refractive cylinder (P = 0.3 at 3 months, P = 0.4 at 6 months, P = 0.2 at 1 year, and P = 0.1 after suture removal). Visual acuity increased from 0.23+/-0.10 at the 3-month evaluation to 0.54+/-0.19 after suture removal. After suture removal, there was a statistically significant inverse correlation between VA and tilt (P = 0.02 in patients with keratoconus and P = 0.05 in those with Fuchs' dystrophy). CONCLUSIONS: Zernike representation of corneal topography height data renders a reconstruction of clinically relevant corneal topography parameters with a marked reduction of redundance and a small error. Correlation of amount/axis of refractive cylinder with respective Zernike parameters is more accurate than with keratometry or respective SimK values of corneal topography analysis. 相似文献
26.
"Orientation teeth" in non-mechanical laser corneal trephination for penetrating keratoplasty: 2.94 microm Er:YAG v 193 nm ArF excimer laser. 下载免费PDF全文
A. Behrens B. Seitz M. Kuchle A. Langenbucher M. Kus C. Rummelt G. Naumann 《The British journal of ophthalmology》1999,83(9):1008-1012
BACKGROUND/AIMS: "Orientation teeth" at the donor trephination margin and correspondent "notches" at the host margin facilitate graft orientation and avoid "horizontal torsion" induced by asymmetric suture placement. In this study the quality and reproducibility of these structures created by non-mechanical laser corneal trephination were compared using two laser emissions. METHODS: The procedure was performed in 20 enucleated pigs' eyes using open metal masks with eight "orientation teeth/notches" (0.3 x 0.15 mm, base x height), an automated globe rotation device, and either a 193 nm ArF excimer laser or a Q switched 2.94 microm Er:YAG laser. "Teeth/notches" were analysed by planimetry and scanning electron microscopy (SEM). RESULTS: Mean size was 0.30 (0.027) x 0. 16 (0.017) mm for "teeth" and 0.30 (0.035) x 0.15 (0.021) mm for "notches" (excimer), and 0.31 (0.022) x 0.16 (0.015) mm and 0.30 (0.031) x 0.14 (0.021) mm respectively (Er:YAG). Overall, variability of notches was higher than that of teeth. By SEM, comparable cut regularity and sustained ablation profile were observed with both lasers. However, the corneal surface at the cut edge appeared slightly elevated (=35 microm) in the Er:YAG group. CONCLUSION: Orientation teeth/notches resembling those obtained with the excimer laser can be created using the Q switched Er:YAG laser, with potential advantages of lower costs, convenient equipment size, and solid state safety. 相似文献
27.
28.
Specific chromosomal losses have been reported for various human tumors. We have now investigated ten cases of urothelial carcinoma and observed genomic alterations by a new method allowing detection of chromosomal losses directly in the tissue section. In 6 out of 8 male carcinomas, the Y-chromosome was lost either in single cells and isolated areas or in extended regions of the tumor sample. Presence of chromosome 1 served as an internal control. This new in situ method allows studies of chromosomal alterations in relation to their tumor topology and the observations constitute the first report on such localised tumor-specific genomic changes. 相似文献
29.
Wunderlich G Suchan B Volkmann J Herzog H Hömberg V Seitz RJ 《Archives of neurology》2000,57(4):561-565
OBJECTIVE: To investigate the cerebral metabolic and functional patterns during recovery from cortical blindness. DESIGN: Follow-up study with serial clinical, metabolic, and functional imaging and visual evoked potentials. CASE PRESENTATION: A 24-year-old woman suffered from cortical blindness after cardiac arrest and recovered over a 6-month period. During recovery, she experienced complex visual hallucinations that could be initiated by visual imagery. RESULTS: Initially, the regional cerebral metabolic rate of glucose was severely reduced in the visual and parieto-occipital cortex bilaterally but recovered almost completely. Visual hallucinations led to significant increases of the regional cerebral blood flow in the initially severely hypometabolic parieto-occipital and temporo-lateral cortex. CONCLUSIONS: Recovery of vision was related to normalization of the postlesionally dysfunctional cortex. Visual hallucinations appeared as the clinical correlate of the electrophysiological hyperexcitability of the recovering partially damaged visual cortex. 相似文献
30.
Broca's region subserves imagery of motion: a combined cytoarchitectonic and fMRI study 总被引:9,自引:0,他引:9
Binkofski F Amunts K Stephan KM Posse S Schormann T Freund HJ Zilles K Seitz RJ 《Human brain mapping》2000,11(4):273-285
Broca's region in the dominant cerebral hemisphere is known to mediate the production of language but also contributes to comprehension. Here, we report the differential participation of Broca's region in imagery of motion in humans. Healthy volunteers were studied with functional magnetic resonance imaging (fMRI) while they imagined movement trajectories following different instructions. Imagery of right-hand finger movements induced a cortical activation pattern including dorsal and ventral portions of the premotor cortex, frontal medial wall areas, and cortical areas lining the intraparietal sulcus in both cerebral hemispheres. Imagery of movement observation and of a moving target specifically activated the opercular portion of the inferior frontal cortex. A left-hemispheric dominance was found for egocentric movements and a right-hemispheric dominance for movement characteristics in space. To precisely localize these inferior frontal activations, the fMRI data were coregistered with cytoarchitectonic maps of Broca's areas 44 and 45 in a common reference space. It was found that the activation areas in the opercular portion of the inferior frontal cortex were localized to area 44 of Broca's region. These activations of area 44 can be interpreted to possibly demonstrate the location of the human analogue to the so-called mirror neurones found in inferior frontal cortex of nonhuman primates. We suggest that area 44 mediates higher-order forelimb movement control resembling the neuronal mechanisms subserving speech. 相似文献