全文获取类型
收费全文 | 6742篇 |
免费 | 652篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 238篇 |
妇产科学 | 107篇 |
基础医学 | 883篇 |
口腔科学 | 239篇 |
临床医学 | 775篇 |
内科学 | 1135篇 |
皮肤病学 | 229篇 |
神经病学 | 814篇 |
特种医学 | 562篇 |
外科学 | 983篇 |
综合类 | 111篇 |
一般理论 | 4篇 |
预防医学 | 588篇 |
眼科学 | 48篇 |
药学 | 366篇 |
中国医学 | 3篇 |
肿瘤学 | 265篇 |
出版年
2021年 | 70篇 |
2020年 | 57篇 |
2019年 | 71篇 |
2018年 | 106篇 |
2017年 | 82篇 |
2016年 | 85篇 |
2015年 | 99篇 |
2014年 | 146篇 |
2013年 | 208篇 |
2012年 | 256篇 |
2011年 | 262篇 |
2010年 | 181篇 |
2009年 | 195篇 |
2008年 | 264篇 |
2007年 | 236篇 |
2006年 | 276篇 |
2005年 | 263篇 |
2004年 | 276篇 |
2003年 | 260篇 |
2002年 | 244篇 |
2001年 | 255篇 |
2000年 | 244篇 |
1999年 | 218篇 |
1998年 | 131篇 |
1997年 | 123篇 |
1996年 | 126篇 |
1995年 | 109篇 |
1994年 | 124篇 |
1993年 | 110篇 |
1992年 | 152篇 |
1991年 | 159篇 |
1990年 | 147篇 |
1989年 | 162篇 |
1988年 | 150篇 |
1987年 | 140篇 |
1986年 | 111篇 |
1985年 | 111篇 |
1984年 | 90篇 |
1983年 | 50篇 |
1982年 | 64篇 |
1981年 | 54篇 |
1980年 | 61篇 |
1979年 | 61篇 |
1978年 | 60篇 |
1977年 | 63篇 |
1976年 | 64篇 |
1975年 | 84篇 |
1974年 | 59篇 |
1973年 | 58篇 |
1972年 | 59篇 |
排序方式: 共有7404条查询结果,搜索用时 15 毫秒
61.
JE Robb LA Rymaszewski HB Bentley PT Donnan 《Surgical and radiologic anatomy : SRA》1991,13(3):181-185
Summary This study investigated the effect of tilt and observer reliability on radiographic measurements of the position of a prosthetic acetabular cup in seven dry bone pelves using the teardrop as a landmark. Coronal or sagittal tilt of more than five degrees was easily recognisable and there was effectively no observer variation in the measurements up to this limit. In addition, 90 out of 100 randomly selected antero-posterior pelvic radiographs from an outpatient department were not significantly rotated and 93 demonstrated a clearly defined teardrop. Measurements about the teardrop on routine radiographs are therefore sufficiently accurate to allow assessment of prosthetic position.
La valeur du sourcil cotyloidien comme repère d'analyse radiologique
Résumé Cette étude, conduite sur 7 bassins secs, apprécie l'effet de l'inclinaison du bassin sur la qualité de l'analyse radiographique de la position d'une cupule prothétique de hanche en utilisant le sourcil cotyloïdien comme repère. Une inclinaison du bassin dans les plans coronal et sagittal est aisément détectable et il n'existe pas de variation d'analyse entre les différents observateurs en dessous de 5° d'inclinaison. De plus, sur 100 radiographies antéro-postérieures de bassin choisies au hasard dans les dossiers de consultation, 90 avaient été réalisées sans incidence particulièrement adaptée et l'on pouvait repérer facilement le sourcil sur 93% d'entre elles. Les mesures faites sur des radios de routine sont donc suffisamment précises pour permettre l'évaluation de la position d'une prothèse à partir du sourcil cotyloïdien.相似文献
62.
Cultured neurons derived from mouse spinal cord were studied using intracellular recording techniques. Effects of muscarinic cholinergic antagonists (atropine) on voltage-dependent membrane events, which could not be related to muscarinic receptors are described. Atropine (in nanomolar to micromolar concentrations) blocks calcium conductances in a manner which is not blocked by carbachol (100 microM). A direct effect of atropine on membrane Ca2+ conductances is suggested. 相似文献
63.
C R Payne J W Hadfield P G Stovin V Barker B E Heard J E Stark 《Journal of clinical pathology》1981,34(7):773-778
The accuracy of diagnosis in 656 patients with the four common histopathological types of primary lung cancer has been assessed by comparing the cell type diagnosis made on cytological and histological investigation with that determined by examination of the surgically resected or necroscopy specimen. The accuracy of diagnosis achieved by cytological examination of sputum and bronchial aspirate, and by bronchial biopsy histology was over 85%. The least accurate diagnostic procedure was percutaneous needle biopsy (62%). Squamous and small cell tumours were accurately diagnosed by all four investigations but errors were made in the diagnosis of large cell and adenocarcinomas. Nearly half the number of patients (43%) with large cell carcinoma were later reclassified as having squamous carcinoma and of the patients with adenocarcinoma 32% had been predicted to be squamous and 18% large cell carcinoma. We consider such quality control of pretreatment diagnosis mandatory in management of individual patients and before enrollment in clinical trials. 相似文献
64.
Coding haplotype analysis supports HCR as the putative susceptibility gene for psoriasis at the MHC PSORS1 locus 总被引:13,自引:0,他引:13
Asumalahti K Veal C Laitinen T Suomela S Allen M Elomaa O Moser M de Cid R Ripatti S Vorechovsky I Marcusson JA Nakagawa H Lazaro C Estivill X Capon F Novelli G Saarialho-Kere U Barker J Trembath R Kere J;Psoriasis Consortium 《Human molecular genetics》2002,11(5):589-597
PSORS1, near HLA-C, is the major genetic determinant of psoriasis. We present genetic and structural evidence suggesting a major role for the HCR gene at the PSORS1 locus. Genotyping of 419 families from six populations revealed that coding single-nucleotide polymorphisms of HCR formed a conserved allele HCR*WWCC that associated highly significantly with psoriasis and with the HLA-Cw6 allele in all populations. Because of strong linkage disequilibrium between HLA-Cw6 and HCR*WWCC, the two genes could not be genetically distinguished by this sample size. However, the variant HCR allele was predicted to differ in secondary structure from the wild-type protein. HCR protein expression in lesional psoriatic skin differed considerably from that observed in normal skin. These results provide strong evidence for the HCR*WWCC allele as a major genetic determinant for psoriasis, probably by a mechanism impacting on keratinocyte proliferation. 相似文献
65.
Transcranial magnetic stimulation 总被引:2,自引:0,他引:2
Bächtold D Baumann T Sándor PS Kritos M Regard M Brugger P 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2001,136(1):128-132
We investigated the effects of unilateral cold-water vestibular stimulation on healthy subjects' performance in two cognitive tasks known to be differentially mediated by the two cerebral hemispheres. In a first experiment (right-hemisphere task), subjects memorized object-location associations while being stimulated with cold water in the left ear or right ear or not at all (control group). In the second experiment (left-hemisphere task), subjects memorized a list of sequentially presented function words while being stimulated in the same manner as the subjects in the first experiment. A recall phase followed each encoding phase. In the first experiment, subjects who had been stimulated in the left ear recalled the object locations significantly faster than subjects who had been stimulated in the right ear and those in the control group. The second experiment yielded the reverse pattern: correct word recognition was faster for subjects who had been stimulated in the right ear than for subjects stimulated in the left ear and those of the control group. We suggest that unilateral caloric stimulation leads to a selective activation of contralateral cerebral structures and speeds up cognitive processes mediated by these structures. These results are discussed with respect to findings in neglect patients and functional-imaging studies in healthy subjects. 相似文献
66.
The p75 neurotrophin receptor (p75(NTR)) is involved in the regulation of neuronal survival and phenotype, but its signal transduction mechanisms are poorly understood. Recent evidence has implicated the cytoplasmic protein NRAGE (neurotrophin receptor-interacting MAGE (from Melanoma AntiGEn) homolog) in p75(NTR) signaling. To gain further insight into the role of NRAGE, we investigated the co-expression of NRAGE and p75(NTR) in mature rat brain. In all areas examined, NRAGE appeared to be confined to neurons. In the basal forebrain cholinergic complex, NRAGE immunoreactivity was evident in all p75(NTR)-positive neurons. There were many more NRAGE-positive than p75(NTR)-positive neurons in these regions, however. NRAGE was also expressed in areas of the basal forebrain that did not express p75(NTR), including the lateral septal nucleus and the nucleus accumbens. A finding in marked contrast to previous studies was the presence of p75(NTR) immunoreactivity in neuronal cell bodies in the hippocampus. Hippocampal p75(NTR) immunoreactivity was apparent in rats 6 months and older, and was localized to the dentate gyrus and stratum oriens. All p75(NTR)-positive neurons in the dentate gyrus and hippocampal formation were positive for NRAGE. The majority of granular cells of the dentate gyrus and pyramidal cells in the hippocampal formation were positive for NRAGE and negative for p75(NTR). NRAGE was also present in some neuronal populations that express p75(NTR) after injury, including striatal cholinergic interneurons, and motor neurons. A region of marked disparity was the cerebral cortex, in which NRAGE immunoreactivity was widespread whereas p75(NTR) was absent. The results are consistent with an important role for NRAGE in p75(NTR) signaling, as all cells that expressed p75(NTR) also expressed NRAGE. The wider distribution of NRAGE expression suggests that NRAGE may also participate in other signaling processes. 相似文献
67.
APC mutation and tumour budding in colorectal cancer 总被引:14,自引:0,他引:14
Jass JR Barker M Fraser L Walsh MD Whitehall VL Gabrielli B Young J Leggett BA 《Journal of clinical pathology》2003,56(1):69-73
AIM: To determine the frequency of tumour budding and somatic APC mutation in a series of colorectal cancers stratified according to DNA microsatellite instability (MSI) status. Material/Methods: Ninety five colorectal cancers were genotyped for APC mutation in the mutation cluster region (exon 15) and scored for the presence of tumour budding at the invasive margin in haematoxylin and eosin stained sections. A subset was immunostained for beta catenin and p16. RESULTS: The frequency of both somatic APC mutation and tumour budding increased pari passu in cancers stratified as sporadic MSI high (MSI-H), hereditary non-polyposis colorectal cancer (HNPCC), MSI low (MSI-L), and microsatellite stable (MSS). Both budding and APC mutation were significantly less frequent in sporadic MSI-H cancers than in MSI-L or MSS cancers. Tumour buds were characterised by increased immunostaining for both beta catenin and p16. CONCLUSION: Tumour budding is associated with an adverse prognosis. The lack of budding in MSI-H colorectal cancer may account for the improved prognosis of this subset and may be explained by an intact WNT signalling pathway and/or inactivated p16(INK4a). 相似文献
68.
Characterization of the dominant autoreactive T-cell epitope in spontaneous autoimmune haemolytic anaemia of the NZB mouse 总被引:3,自引:0,他引:3
Shen CR Ward FJ Devine A Luross JA Lowrey PA Wraith DC Elson CJ Barker RN 《Journal of autoimmunity》2002,18(2):149-157
NZB mice spontaneously develop autoimmune haemolytic anaemia (AIHA) due to a T helper-dependent autoantibody response against the erythrocyte anion channel protein, Band 3. Here, we characterize the recognition of the Band 3 sequence 861-874, which carries the dominant, I-E(d)-restricted T cell epitope. The ability of N and C-terminal truncated versions of peptide 861-874 to elicit NZB splenic T-cell proliferation indicated that the core epitope spans residues 862-870. Next, a set of alanine substitution analogues was tested to determine which residues functioned either as MHC anchor or TCR contact residues. A combination of proliferation and MHC:peptide binding assays identified residues 862(L), 864(V), 865(L), and 869(K) as I-E(d) anchor residues, and 868(V) as the only TCR contact residue. The ability of the wild-type sequence 861-874 to compete with a high affinity reference peptide for binding to I-E(d) indicates that the escape of pathogenic NZB T cells from purging of the autoreactive repertoire cannot be attributed to ineffective presentation of peptide 861-874 by its restricting element. It will now be possible to design altered peptide ligands of Band 3 861-874, in order to further dissect the mechanisms responsible for the maintenance and loss of T cell tolerance to RBC autoantigens, and to modulate the immune response in AIHA. 相似文献
69.
We isolated bacteria from ticks, lice and fleas. Partial small subunit rRNA sequences were obtained for each isolate and the closest matches in the FastA database were determined. These bacteria were mostly Gram-positive (Firmicutes), although representatives from the Proteobacteria (alpha, beta, gamma subdivisions) and CFB group were also isolated. Most of the isolates we found were from genera that were present in most of the ectoparasites studied, but a few genera were restricted to one species of ectoparasite. The most commonly isolated genera were Stenotrophomonas, Staphylococcus, Pseudomonas, Acinetobacter and Bacillus. Species of Bacillus and Proteus, which have biopesticide potential, were found in some of these ectoparasites. Overall, the communities of bacteria were similar to those found in other studies of parasitic arthropods. 相似文献
70.