全文获取类型
收费全文 | 3527篇 |
免费 | 194篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 261篇 |
妇产科学 | 32篇 |
基础医学 | 393篇 |
口腔科学 | 86篇 |
临床医学 | 363篇 |
内科学 | 743篇 |
皮肤病学 | 68篇 |
神经病学 | 234篇 |
特种医学 | 422篇 |
外科学 | 289篇 |
综合类 | 31篇 |
预防医学 | 204篇 |
眼科学 | 79篇 |
药学 | 285篇 |
1篇 | |
中国医学 | 11篇 |
肿瘤学 | 226篇 |
出版年
2021年 | 28篇 |
2020年 | 29篇 |
2019年 | 34篇 |
2018年 | 44篇 |
2017年 | 45篇 |
2016年 | 61篇 |
2015年 | 79篇 |
2014年 | 71篇 |
2013年 | 114篇 |
2012年 | 92篇 |
2011年 | 81篇 |
2010年 | 95篇 |
2009年 | 114篇 |
2008年 | 83篇 |
2007年 | 110篇 |
2006年 | 106篇 |
2005年 | 116篇 |
2004年 | 82篇 |
2003年 | 93篇 |
2002年 | 93篇 |
2001年 | 85篇 |
2000年 | 90篇 |
1999年 | 101篇 |
1998年 | 131篇 |
1997年 | 137篇 |
1996年 | 137篇 |
1995年 | 95篇 |
1994年 | 102篇 |
1993年 | 111篇 |
1992年 | 62篇 |
1991年 | 62篇 |
1990年 | 63篇 |
1989年 | 86篇 |
1988年 | 77篇 |
1987年 | 58篇 |
1986年 | 65篇 |
1985年 | 61篇 |
1984年 | 28篇 |
1983年 | 30篇 |
1982年 | 33篇 |
1981年 | 46篇 |
1980年 | 30篇 |
1979年 | 31篇 |
1978年 | 25篇 |
1977年 | 47篇 |
1976年 | 39篇 |
1975年 | 25篇 |
1974年 | 26篇 |
1973年 | 32篇 |
1971年 | 26篇 |
排序方式: 共有3749条查询结果,搜索用时 31 毫秒
51.
Helmut Seidel Ralph Blüthner Janos Martin Gerhard Menzel Rudolf Panuska Peter Ullsperger 《European journal of applied physiology》1992,65(4):376-382
Summary Auditory event-related brain potentials (ERP) in response to two different tone stimuli (1.1 kHz or 1 kHz, 80 dB, 50 ms; given by headphones at a regular interstimulus interval of 5 s with a probability distribution of 70:30) were recorded from 12 healthy male subjects (Ss) during four different conditions with two repetitions: A - 60 dBA white noise (wN), no wholebody vibration (WBV); B - 60 dBA wN plus sinusoidal WBV in the az-direction with a frequency of 2.01 Hz and acceleration of 2 m ·s–2 root mean square; C - 80 dBA wN, no WBV; D - 80 dBA wN plus WBV. Each condition consisted of two runs of about 11 min interrupted by a break of 4 min. During the break with continuing exposure, but without auditory stimuli, Ss judged the difficulty of the tone-detection task and intensity of noise by means of cross-modality matching (CMM). Vibration-synchronous activity in the electrocardiogram was eliminated by a subtraction-technique. Noise caused an attenuation of the N1 and P2 amplitudes and prolongation of P3 latencies. The WBV did not cause systematic ERP effects. Condition B was associated with higher N1 and smaller P3 amplitudes. The factor condition had a significant effect on the peak latencies of P3 to target stimuli and the task difficulty judged by CMM. Both effects exhibited significant linear increases in the sequence of conditions A, B, C, D. For the evaluation of exposure conditions at work, it can be suggested that noise has a strong systematic effect which can be enhanced by WBV. The P3 latency is considered as an advantageous measure for the detection of objective effects of physical environmental factors, correlating with relevant subjective responses. 相似文献
52.
53.
54.
Vaughan JR; Farrer MJ; Wszolek ZK; Gasser T; Durr A; Agid Y; Bonifati V; DeMichele G; Volpe G; Lincoln S; Breteler M; Meco G; Brice A; Marsden CD; Hardy J; Wood NW 《Human molecular genetics》1998,7(4):751-753
A mutation in exon 4 of the human alpha-synuclein gene was reported
recently in four families with autosomal dominant Parkinson's disease (PD).
In order to examine whether mutations in this exon or elsewhere in the gene
are common in familial PD, all seven exons of the alpha- synuclein gene
were amplified by PCR from index cases of 30 European and American
Caucasian kindreds affected with autosomal dominant PD. Each product was
sequenced directly and examined for mutations in the open reading frame. No
mutations were found in any of the samples examined. We conclude that the
A53T change described in the alpha- synuclein gene is a rare cause of PD or
may even be a rare variant. Mutations in the regulatory or intronic regions
of the gene were not excluded by this study.
相似文献
55.
Distribution of mutations in the PEX gene in families with X-linked hypophosphataemic rickets (HYP) 总被引:8,自引:0,他引:8
Rowe PS; Oudet CL; Francis F; Sinding C; Pannetier S; Econs MJ; Strom TM; Meitinger T; Garabedian M; David A; Macher MA; Questiaux E; Popowska E; Pronicka E; Read AP; Mokrzycki A; Glorieux FH; Drezner MK; Hanauer A; Lehrach H; Goulding JN; O'Riordan JL 《Human molecular genetics》1997,6(4):539-549
Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with
homologies to endopeptidases, on the X-chromosome), are responsible for
X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family
of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has
raised important questions regarding PEX function at the molecular level.
The aim of this study was to analyse 99 HYP families for PEX gene
mutations, and to correlate predicted changes in the protein structure with
Zn2+ metallopeptidase gene function. Primers flanking 22 characterised
exons were used to amplify DNA by PCR, and SSCP was then used to screen for
mutations. Deletions, insertions, nonsense mutations, stop codons and
splice mutations occurred in 83% of families screened for in all 22 exons,
and 51% of a separate set of families screened in 17 PEX gene exons.
Missense mutations in four regions of the gene were informative regarding
function, with one mutation in the Zn2+-binding site predicted to alter
substrate enzyme interaction and catalysis. Computer analysis of the
remaining mutations predicted changes in secondary structure,
N-glycosylation, protein phosphorylation and catalytic site molecular
structure. The wide range of mutations that align with regions required for
protease activity in NEP suggests that PEX also functions as a protease,
and may act by processing factor(s) involved in bone mineral metabolism.
相似文献
56.
Identification of the multiple endocrine neoplasia type 1 (MEN1) gene. The European Consortium on MEN1 总被引:10,自引:0,他引:10
Lemmens I; Van de Ven WJ; Kas K; Zhang CX; Giraud S; Wautot V; Buisson N; De Witte K; Salandre J; Lenoir G; Pugeat M; Calender A; Parente F; Quincey D; Gaudray P; De Wit MJ; Lips CJ; Hoppener JW; Khodaei S; Grant AL; Weber G; Kytola S; Teh BT; Farnebo F; Thakker RV 《Human molecular genetics》1997,6(7):1177-1183
57.
Frank Queisser Ralph Blüthner Dieter Bräuer Helmut Seidel 《European journal of applied physiology》1994,68(1):92-101
A group of 12 healthy men volunteered for the experiment. Electromyograms (EMG) were obtained from semispinalis capitis, splenius capitis, levator scapulae, and trapezius muscles. The flexion angle of the cervical spine was precisely adjusted to 0°, 10°, 20°, and 30° relative to the horizontal, with a constant angle of the atlanto-occipital joint. The subjects made eight short (about 2 s) vertical extension forces (6%, 12%,18%, 24%, 30%, 36%, 42%, and 48% of maximal voluntary peak contraction force). For each position, the centre of pressure under the head was determine as the basis for the calculation of the external lever arm. The presence of motor endplate regions was ascertained by multiple surface electrodes. The slopes of individual linear regression lines for the root mean square (rms)-values were dependent on the existence of endplates in the area of the electrodes — endplates caused smaller rms values per Newton metres of external torque. Significant intersubject differences between regression equations could not be eliminated by the normalization of EMG-parameters and/or torques. The elimination of gravity, the continuous monitoring of positions, and the consideration of localization of motor endplate regions were essential prerequisites for the acquisition of reliable relationships between EMG of different neck muscles and external torques. Two important conclusions were derived for the prediction of torques from EMG measurements: firstly, individual regression equations which take into account the position of the head and neck should be used; secondly, normalization procedures do not justify the application of average regressions to a group of subjects. 相似文献
58.
Rigor and resistance to stretch in vertebrate smooth muscle 总被引:2,自引:0,他引:2
59.
The aim of this study was to evaluate quantitatively the behaviour of in vivo hydroxyapatite coated implants (HA) in the rabbit over time, and to compare the results with observations made on titanium plasma spray implants (TPS). Results were analysed according to the percentage of bone contact. Eighteen HA cylindrical implants (3.25 x 8 mm) and 6 TPS cylindrical implants from Steri-Oss were placed in the epiphysis of the femur in 24 white rabbits. Each rabbit received one implant. Three rabbits with one HA implant (n = 3) and 1 rabbit with one TPS implant (n = 1) were sacrificed after implantation periods of 2, 4, 6, 8, 10 and 12 months. Implants were cut along the long axis and prepared for histological and histomorphometrical evaluations. Measurements of coating thickness and percentage of bone contact were performed with scanning electron microscopy analysis on the sides of the implant, in 3 different types of bone, namely cortical, trabecular and marrow. In cortical bone, dense bone was apposed to the HA implants: from 92.3 +/- 5.5% at 2 months to 89.6 +/- 6.5% at 1 year, with no significant regression of HA thickness (P = 0.37). TPS coating showed less bone contact, but thickness was stable (P = 0.46). In trabecular zone, where bone contact was less pronounced, a significant regression of HA coatings thickness (P < 0.05) was observed. Nevertheless TPS coatings were stable (P = 0.81). Histomorphometrical results demonstrated that a highly significant regression (P < 0.0001) of HA thickness was observed in the marrow area, where the bone-to-implant contact never exceeded 7.6% from 2 to 12 months. TPS coating did not reveal any sign of resorption (P = 0.88), despite a rare bone contact. Histological analysis revealed inflammatory and giant cells, principally in the marrow area in contact with HA coating, but always in restrictive numbers. We conclude that bone contact protected the HA coating from resorption. 相似文献
60.
Billette J; Janse MJ; van Capelle FJ; Anderson RH; Touboul P; Durrer D 《The American journal of physiology》1976,231(4):1129-1139