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91.
Immunogenicity and protective efficacy of the alpha C protein of group B streptococci are inversely related to the number of repeats. 总被引:6,自引:3,他引:6 下载免费PDF全文
C Gravekamp D L Kasper J L Michel D E Kling V Carey L C Madoff 《Infection and immunity》1997,65(12):5216-5221
Infection by group B streptococci (GBS) is an important cause of bacterial disease in neonates. Alpha C protein is a protective cell surface-associated protein of GBS. This protein contains a repeat region flanked by N and C termini. Variable expression of tandem repeating units of alpha C proteins had been found among clinical isolates of GBS. We examined the effect of the number of repeats on the immunogenicity of the alpha C protein and its ability to elicit protection from GBS infection in a neonatal mouse model. Mice were immunized with purified alpha C proteins of constructs containing various numbers of repeats (n = 1, 2, 9, and 16) and the N- and C-terminal regions. Both the N-terminal and the repeat regions contain protective and opsonic epitopes. Antibody responses to the alpha C protein constructs with various numbers of repeats were tested with enzyme-linked immunosorbent assay plates coated with either native, nine-repeat alpha C protein or "repeatless" N-terminal antigen. An inverse relationship was found between the number of repeats and the immunogenicity of the alpha C protein; this effect was most pronounced on titers of antibody to the N-terminal region. An inverse relationship was also observed between the number of repeats and protective efficacy, i.e., mouse dams immunized with 5 microg of one- or nine-repeat alpha C protein transferred protective immunity to 65 or 11% of their pups, respectively (P < 0.0001). Thus, the presence of multiple repeats appears to lessen the antibody response to the complete alpha C protein, and especially the antibody response to its N-terminal region, and suggests a mechanism whereby repeat elements contribute to the evasion of host immunity. 相似文献
92.
Boisgard S Moreau PE Descamps S Courtalhiac C Silbert H Moreel P Michel JL Levai JP 《Surgical and radiologic anatomy : SRA》2003,25(3-4):330-334
The epicondylar axis is a reliable reference to check the rotation of the femoral implant in total knee prostheses (TKPs). However, during the operation it seems easier to use the posterior condylar axis as a landmark. The angle between these two axes is called the posterior condylar angle (PCA). The aim of this study was to measure the PCA in arthritic knees to assess the reliability of the posterior condylar axis as a reference for the control of the rotation of the femoral implant and to look for correlation with other radiological measurements. This prospective study consisted of 103 arthritic knees (81 varus, 22 valgus) before a TKP had been done in 103 patients (75 women, 28 men). The assessment of the PCA was made by computed tomographic scanning (CT). The HKA, HKS and HKT angles were measured on the pangonogram. The posterior condylar axis was internally rotated with respect to the epicondylar axis. The average value for all the patients was 2.65° degrees with a range from 0° to 7°. The PCA was significantly increased in the valgus knees. There was no correlation between the angles on the pangonogram and the posterior condylar axis. While the preoperative assessment of the PCA by CT scanning is reliable, the results obtained indicate the marked variability in its value. If one wishes to use the posterior condylar axis as a guide for rotation, it is therefore necessary to assess the PCA for each patient using adjustable jigs according to the value obtained. No measurement on standard radiographs allowed an extrapolation of the value of the PCA, and CT scanning seems to be the preferable radiological examination.
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Etude tomodensitométrique de l'angle condylien postérieur dans les genoux arthrosiques. Intérêt dans le positionnement en rotation de l'implant fémoral dans les prothèses totales de genou
Résumé L'axe épicondylien est une référence fiable pour le contrôle de la rotation de l'implant fémoral dans les prothèses totales de genou (PTG). Mais, lors de l'intervention, il semble plus facile d'utiliser l'axe condylien postérieur comme repère. L'angle entre ses deux axes est appelé angle condylien postérieur (ACP). Le but de cette étude était de mesurer l'ACP dans les genoux arthrosiques, d'évaluer la fiabilité de l'axe condylien postérieur comme référence pour le réglage de la rotation de l'implant fémoral, de rechercher une corrélation avec d'autres mesures radiologiques. Une étude prospective comportant 103 genoux arthrosiques (81 varus et 22 valgus), avant PTG a été effectuée, chez 103 patients (75 femmes et 28 hommes). L'évaluation de l'ACP a été faite par examen tomodensitométrique (TDM). Les angles HKA, HKS et HKT ont été mesurés sur le pangonogramme. L'axe condylien postérieur était en rotation interne par rapport à l'axe épicondylien. La valeur moyenne pour tous les patients était de 2.65°, avec des valeurs de 0 à 7°. La valeur de l'angle CP augmentait avec une différence significative dans le groupe des genu valgum. Il n'y avait pas de corrélation entre les angles du pangonogramme et l'ACP. Si l'évaluation pré-opératoire de l'ACP par TDM est fiable, les résultats obtenus mettent en évidence une variabilité importante de sa valeur. Il faut donc, si l'on veut utiliser l'axe condylien postérieur comme repère de rotation, évaluer pour chaque patient l'ACP, et utiliser un ancillaire réglable reportant la valeur obtenue. Aucune mesure sur des radiographies standard ne permettant d'extrapoler la valeur de l'ACP, la TDM semble l'examen radiologique de choix.相似文献
93.
Kozo Hirata Tetsuo Nagasaka Tadahiro Nunomura Michel Cabanac 《European journal of applied physiology》1988,58(1-2):92-96
Summary The effects of local heating on finger blood flow (BF) and local thermal sensation (Sens
w
) were studied. Finger BFs in both hands were measured simultaneously; one hand was immersed in water the temperature (T
w
) of which was raised from 35° C to 43°C by steps of 2° C every 10 min, while the other hand was kept atT
w
35°C. FingerBF in the locally heated hand decreased atT
w
37 to 41°C, while fingerBF in the control hand did not alter. Sensw, in the heated hand showed a dynamic response, initially increasing concomitantly with an increase inT
w
, then gradually returning and adapting to a new level of Sensw. The dynamic response of Sensw, was not perceived during mental calculation even whenT
w
was raised to 40°C, and the reduction in finger blood flow was not observed. These results suggest that finger vasoconstriction caused by local heating closely relates to the dynamic response characteristic of local thermal sensation atT
w
above core temperature, and that the perception of local thermal sensation in the central nervous system is involved in the mechanism of this vasoconstrictor response. 相似文献
94.
De Wit D Tonon S Olislagers V Goriely S Boutriaux M Goldman M Willems F 《Journal of autoimmunity》2003,21(3):277-281
Toll-like receptor (TLR)-4 signaling pathway plays an essential role in host defense against gram-negative bacteria while TLR-3-mediated signaling is critically involved in anti-viral immunity. To gain insight into the defects responsible for impaired Th1 responses in human newborns, we investigated the responses of human cord blood cells to lipopolysaccharide, LPS, and to polyinosinic-polycytidylic acid, Poly (I:C), ligands of TLR-4 and TLR-3, respectively. Measurement of cytokine levels revealed a profound defect in IL-12 (p70) synthesis and an increased release of IL-10 in cord blood exposed to LPS or Poly (I:C), as compared to adult blood. Moreover, Poly (I:C)-induced IFN-alpha production was found to be significantly impaired in cord blood. Phenotypic maturation of myeloid DC in response to LPS or Poly (I:C) was next compared in cord and adult blood. We observed that neonatal myeloid DC displayed decreased upregulation of CD40, CD80 whereas CD86 and HLA-DR upregulation did not differ significantly between adults and neonates. Taken together, these findings might be relevant to the increased vulnerability of human newborns to intracellular pathogens and to their inability to develop efficient Th1-type responses. 相似文献
95.
Sodium gradient-energized concentrative transport of adenosine in renal brush border vesicles 总被引:4,自引:0,他引:4
The uptake of adenosine in brush border vesicles of the proximal tubule of the rat kidney has been studied with a filtration technique. The initial rate of uptake was almost 6 times greater in the presence of NaCl than in the presence of KCl. The stimulatory effect of Na+ was strictly dependent on a gradient of Na+ (out>in). The time course of uptake showed an overshoot with a maximum at 20 s with a gradient of NaCl, but not with KCl. Inosine and 5-AMP were produced from adenosine within the vesicles. In the presence of an inhibitor or adenosine deaminase adenosine was not significantly metabolized during the first 20 s of uptake. Thus, kinetic parameters of transport could be studied in the absence of interferences with metabolism. AK
m of 1.1 M and aV
max of 232 pmol · min–1 · mg protein–1 were calculated for the Na+ gradient-dependent transport. The dependency on a Na+ gradient, the capacity for uphill transport and the high affinity for adenosine situate this transport system apart from the mechanisms of transport of nucleosides described so far. It may be relevant in regard to the role of adenosine in the regulation of glomerular filtration.Abbreviations used EHNA
erythro-9-(2-hydroxy-3-nonyl)adenine
- FCCP
carbonylcyanide p-trifluoromethoxy-phenylhydrazone
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- Tris
tris (hydroxymethyl)-aminomethane 相似文献
96.
97.
Cloned alpha and beta C-protein antigens of group B streptococci elicit protective immunity. 总被引:8,自引:5,他引:8 下载免费PDF全文
Streptococcus agalactiae (group B streptococci [GBS]) is the leading cause of neonatal sepsis and meningitis in the United States. The surface-associated C proteins of GBS play a role in immunity, but their number, size, structure, function, and virulence properties have not been well characterized. A recombinant library of DNA fragments from GBS strain A909 (type Ia/C) was prepared in the plasmid pUX12, a specially constructed Escherichia coli expression vector. The library was screened with a rabbit antiserum shown to be protective for passive immunity to GBS infection in a mouse lethality model. Clones were divided into two distinct groups on the basis of DNA-DNA cross-hybridization, restriction enzyme analysis, and the expression of antigenic proteins in E. coli. A characteristic clone from each group was chosen for further study. Clone pJMS23 expresses gene products that biochemically and immunologically correspond to the trypsin-resistant, C-protein alpha antigen. Clone pJMS1 expresses a gene product that binds to immunoglobulin A and is similar to the trypsin-sensitive, C-protein beta antigen. Antisera raised in rabbits against E. coli containing each of the plasmid clones were able to elicit protective immunity in mice challenged by GBS strains carrying the C proteins but not by non-C-protein-bearing strains. Southern blot analysis shows no DNA homology between the clones, and there is no immunological cross-reactivity between the antigens they express. Therefore, pJMS23 and pJMS1 encode two different C proteins that define unique protective epitopes. 相似文献
98.
Summary Infection of Aedes albopictus cells with Semliki Forest virus (SFV) leads to polykaryocyte formation below pH 6.2. This syncytium formation is accompanied by a decrease of the cellular ATP level. Addition of inhibitors of oxidative phosphorylation leads to a rapid, total depletion of ATP in infected cells at pH 6 and results in an inhibition of polykaryocyte formation. However, when cells were exposed for only a few minutes to pH 6 in the presence of the inhibitors and then kept at pH 7.2, the ATP level partially recovered to values sufficient for syncytium formation. Similar results were obtained after ATP depletion induced by 2-deoxyglucose. Thus, it can be concluded that SFV-induced syncytium formation is an ATP-dependent event.With 6 Figures 相似文献
99.
Detection of Tissue Culture-Adapted Theiler''s Virus RNA in Spinal Cord White Matter Cells Throughout Infection 总被引:3,自引:1,他引:3 下载免费PDF全文
The appearance of histological lesions and the localization of viral RNA in the central nervous system of mice infected with tissue culture-adapted Theiler's murine encephalomyelitis virus (WW strain) (TMEV-WW) was studied. Viral RNA was detected by autoradiography after in situ hybridization, using a 3H-labeled DNA probe complementary to virion RNA, which was applied to deparaffinized sections of central nervous system tissues from infected mice. Subjacent histological sections of tissues were used to assess the location and extent of lesions. Lesions were first observed at 20 days post-inoculation and appeared to enlarge throughout infection. They consisted of infiltrates of mononuclear cells and lymphocytes in spinal cord white matter and leptomeninges; at 78 days post-inoculation severe necrotizing and demyelinative myelitis and gliosis were observed. In contrast to the pathogenesis of brain-derived TMEV-WW-infected mice, no lesions were found in the central nervous system gray matter of mice infected with tissue culture-adapted TMEV-WW at any time post-infection. Tissue culture-adapted viral RNA was found in the cells of spinal cord white matter throughout infection; only one neuron in close proximity to the injection site was found to contain viral RNA shortly after infection. At early times after infection, spinal cord white matter cells containing viral RNA were found before development of inflammatory lesions; at later days post-inoculation, positive cells were found within, at the periphery of, or at a distance from lesions. The number of infected cells and the amount of viral RNA per cell appeared to remain constant from 20 to 78 days post-inoculation despite the increasing intensity of the inflammatory response. The nearly exclusive spinal cord white matter tropism of tissue culture-adapted TMEV-WW appeared to directly correlate with the disease-inducing potential of this virus. 相似文献
100.
Nassim Kamar Karine Sandres-Saune David Ribes Michel Duffaut Jannick Selves Dominique Durand Jacques Izopet Lionel Rostaing 《Journal of clinical virology》2004,31(4):298-303
BACKGROUND: Following renal transplantation (RT), chronic immunosuppression is associated in hepatitis B virus (HBV) (+) patients with a flare-up of the disease, which might be harmful in the long term. OBJECTIVES: We report on the effect of long-term lamivudine therapy given at an initial daily dose of 100mg in 18 HBV (+) RT patients. RESULTS: When lamivudine therapy was commenced, 14 patients (77%) had an increase in their aspartate (AST) and alanine (ALT) aminotransferase levels. During a mean follow-up, under treatment, of 36.5 +/- 3.5 months (up to 66 months), 10 patients (55%) had a sustained partial (HBV DNA < 4 x 10(5)copies/ml) (n = 4) or complete (HBV DNA < 400 copies/ml) (n = 6) virological response. Overall, 12 virological breakthroughs were observed. Of those who were HBe Ag(+) prior to lamivudine therapy (n = 4), one seroconverted to HBe Ab during therapy. At the last follow-up, AST and ALT levels were normal in 13 patients. When liver biopsy was repeated during treatment (n = 15), the virological responders showed a significant decrease in total Knodell score from 10 +/- 0.6 to 7 +/- 1 (P = 0.04), but no significant change in the stage of fibrosis. Conversely, in those patients with high HBV DNA titers, there were no significant changes in the total Knodell score or in the grade of fibrosis. CONCLUSION: In conclusion, lamivudine therapy is safe in HBV(+)ve renal-transplant patients. However, even if the full and partial virological response rates are still high (55%) in the long term, relapse or primary non-responses occur. The implementation of alternative efficient strategies is warranted. 相似文献