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排序方式: 共有373条查询结果,搜索用时 15 毫秒
1.
Two fast magnetic resonance (MR) imaging techniques, advanced Fourier and partial-flip imaging, were used at 0.35 T to examine 21 patients with suspected intracranial lesions; the results were quantitatively compared with a conventional spin-echo study. Both of the fast MR techniques yielded a fourfold reduction in imaging time per section. The advanced Fourier sequence showed contrast that was identical to the conventional spin-echo study with signal-to-noise ratios of 58% and 57% for the first and second echoes, respectively. The partial-flip sequence showed a contrast of 109% and 57% for lesions versus substantia alba, and 107% and 78% for substantia grisea versus substantia alba relative to the first and second echoes of the conventional spin-echo study. The partial-flip sequence was particularly sensitive to magnetic susceptibility; this produced artifacts that may undermine the usefulness of partial flip for routine screening in certain parts of the brain. However, this susceptibility significantly improved the detection of intracranial hemorrhage when compared with the spin-echo sequence, particularly when combined with phase mapping of the partial-flip study. 相似文献
2.
Gilbertson LG Doehring TC Livesay GA Rudy TW Kang JD Woo SL 《Annals of biomedical engineering》1999,27(6):839-843
This study investigated a previously unaccounted for source of error in a high-capacity, six degree-of-freedom load cell used in multi-degree-of-freedom robotic testing of musculoskeletal joints, an application requiring a load cell with high accuracy in addition to high load capacity. A method of calibration is presented for reducing the error caused by changes in universal force-moment sensor (UFS) orientation within a gravitational field. Uncorrected, this error can exceed a magnitude of 1% of the full-scale load capacity—the manufacturer-stated accuracy of the UFS. Implementation of the calibration protocol reduced this error by approximately 75% for a variety of loading conditions. This improvement in load cell accuracy (while maintaining full load capacity) should improve both the measurement and control of specimen kinetics by robotic/UFS and other biomechanical testing systems. © 1999 Biomedical Engineering Society.
PAC99: 8719Rr, 8780Vt, 0620Fn, 0620Dk, 8719Ff 相似文献
3.
Missense mutation in a von Willebrand factor type A domain of the alpha 3(VI) collagen gene (COL6A3) in a family with Bethlem myopathy 总被引:2,自引:0,他引:2
Pan TC; Zhang RZ; Pericak-Vance MA; Tandan R; Fries T; Stajich JM; Viles K; Vance JM; Chu ML; Speer MC 《Human molecular genetics》1998,7(5):807-812
The Bethlem myopathy is a rare autosomal dominant proximal myopathy
characterized by early childhood onset and joint contractures. Evidence for
linkage and genetic heterogeneity has been established, with the majority
of families linked to 21q22.3 and one large family linked to 2q37,
implicating the three type VI collagen subunit genes, COL6A1 (chromosome
21), COL6A2 (chromosome 21) and COL6A3 (chromosome 2) as candidate genes.
Mutations of the invariant glycine residues in the triple-helical
domain-coding region of COL6A1 and COL6A2 have been reported previously in
the chromosome 21-linked families. We report here the identification of a
G-->A mutation in the N-terminal globular domain-coding region of COL6A3
in a large American pedigree (19 affected, 12 unaffected), leading to the
substitution of glycine by glutamic acid in the N2 motif, which is
homologous to the type A domains of the von Willebrand factor. This
mutation segregated to all affected family members, to no unaffected family
members, and was not identified in 338 unrelated Caucasian control
chromosomes. Thus mutations in either the triple-helical domain or the
globular domain of type VI collagen appear to cause Bethlem myopathy.
相似文献
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C Wurthmann J Gregor B Baumann A Schwarz O Effenberger W Doehring B Bogerts 《Progress in neuro-psychopharmacology & biological psychiatry》1999,23(5):823-830
1. This CT study was designed to assess brain morphology in 21 patients with agoraphobia and 21 normal control subjects matched for age and sex. 2. Internal and external CSF spaces were evaluated by qualitative assessment on a 3-point scale (normal, questionable, abnormal). 3. Patients showed bilateral enlargement of prefrontal CSF spaces (p < .05). The rating abnormal" was given in the left hemisphere to 6 (28.6%) of the patients, to 4 (19%) of the patients in the right hemisphere, but to none (0%) of the normal controls. 4. These findings suggest that alterations in brain morphology are involved in the etiology of agoraphobia. 相似文献
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8.
R. Kardorff R. M. Gabone C. Mugashe D. Obiga C. E. Ramarokoto C. Mahlert N. Spannbrucker A. Lang V. Günzler B. Gryseels J. H. H. Ehrich E. Doehring 《Tropical medicine & international health : TM & IH》1997,2(3):230-239
One thousand six hundred and ninety-five inhabitants of 3 rural villages on Ukerewe Island, Lake Victoria, Tanzania, were examined by clinical, parasitological, ultrasonographic and—in part—serological means to evaluate Schistosoma (S.) mansoni-related morbidity on a community level. Villagers frequently complained of typical colitis symptoms (abdominal pain 80.1%, bloody stools 43.1%, diarrhoea 35.1%); haematemesis, on the other hand, was rare (and reports doubtful in most cases). 16.9% of the population had been given praziquantel previously. Overall S. mansoni prevalence was 86.3%, with a median egg output of 176 eggs per gram (e.p.g.) and a maximum output of 17 984 e.p.g. Children and adolescents were infected more severely than adults, men more severely than women. Pretreated individuals excreted significantly fewer ova (median 124 vs 192e.p.g., P<0.001). Hepatomegaly (determined by ultrasonography) was present in 35%, splenomegaly in 80%. Organomegaly was significantly related to egg output. Pretreated persons had lower rates of splenomegaly and left lobe hepatomegaly. Low-degree periportal fibrosis was common, while severe grades of fibrosis (MANAGIL score II and III) were present in about 6%. About 10% had other abnormalities on liver sonography (irregular parenchymal texture and/or shape); these persons passed significantly more S. mansoni ova than others. Clear sonographic signs of portal hypertension were seen in 2.1%. Serum procollagen-IV-peptide and γ-glutamyl-transferase levels were increased in persons with severe periportal fibrosis, irregular liver texture or portofugal collateral vessels. Thus, S. mansoni infection in the western part of Ukerewe Island is frequent and often severe, leading to a high prevalence of gastrointestinal symptoms. Hepatosplenic involvement does occur, although symptomatic cases of portal hypertension were not identified beyond doubt. The overall level of schistosomal morbidity is thus considered intermediate. Serum procollagen-IV-peptide may be a promising marker of schistosomal liver disease. Our data suggest that S. mansoni infection may also be related to diffuse liver parenchyma alterations in this area. 相似文献
9.
CC Thorn M Smith O Aziz TC Holme 《Annals of the Royal College of Surgeons of England》2013,95(1):52-56