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991.
学术背景:最大摄氧量通常被认为是决定中长跑和长跑成绩的一个重要的生理学参数.近年来研究结果显示运动强度可能在提高最大摄氧量扮演着重要的作用.目的:就运动强度与最大摄氧量及运动强度诱导的肌体适应机制相关研究做一综述.检索策略:应用计算机检索http://www.ncbi.nlm.nih.gov网站1979-01/2007-07期间的相关文章,检索词为:“training intensity,maximal oxygen uptake“,限定文章语言种类为English.在检索336篇文献中,含有运动强度与最大摄氧量,运动强度诱导的肌体适应机制等内容文献126篇.文献评价:在126篇文献中,保留近年相关文献31篇文献做进一步分析,其中人体实验21篇,综述、述评、讲座类文献10篇.资料综合:①训练强度在40%~50%最大摄氧量可提高无训者最大摄氧量.②较小的运动强度能够提高最大摄氧量主要取决于起始最大摄氧量.③优秀耐力运动员需要采用高百分比最大摄氧量来提高最大摄氧量.④耐力训练诱导的肌形态的改变,每博输出量的增加,骨骼肌毛细血管增加,肌红蛋白蛋白含量增加,以及Ⅱ型肌纤维抗氧化能力的提高和最大摄氧量增加相关.结论:研究结果显示在95%~100%最大摄氧量运动强度进行训练可有效提高运动者的最大摄氧量.训练强度诱导耐力运动最大摄氧量变化与最大心输出量和最大动静脉氧差有关. 相似文献
992.
Lalloo DG; Trevett AJ; Black J; Mapao J; Saweri A; Naraqi S; Owens D; Kamiguti AS; Hutton RA; Theakston RD; Warrell DA 《QJM : monthly journal of the Association of Physicians》1996,89(1):25-35
Thirty-two patients with enzyme-immunoassay-proven death adder (Acanthophis
sp.) bites were studied in Port Moresby, Papua New Guinea. Eighteen were
envenomed; local signs were rare and none had incoagulable blood, but all
except one had signs of neurotoxicity. Five (27.7%) envenomed patients
required intubation and ventilation. One patient developed renal failure,
previously undescribed following death adder bites. Laboratory
investigations showed mild prolongation of prothrombin and partial
thromboplastin times in some patients. In vitro studies showed that the
venom contains anticoagulant activity, but does not cause fibrinogenolysis.
In contrast to taipan envenoming, neurotoxicity did not progress after
antivenom administration, and there was reversal of neurotoxicity, evident
within 6 h, in three severely envenomed patients treated less than 12 h
after the bite. One patient treated with antivenom and anticholinesterases
had the most dramatic response to treatment; the optimum management of
bites by this species may include prompt treatment with both antivenom and
anticholinesterases in addition to effective first aid.
相似文献
993.
Haemodynamic parameters predicting variceal haemorrhage and survival in alcoholic cirrhosis 总被引:1,自引:0,他引:1
Stanley AJ; Robinson I; Forrest EH; Jones AL; Hayes PC 《QJM : monthly journal of the Association of Physicians》1998,91(1):19-25
The relationship between the various haemodynamic abnormalities observed in
cirrhosis and their prognostic value remains unclear. We report
haemodynamic measurements on 96 patients with alcoholic cirrhosis (mean
Childs-Pugh Score, CPS, 9.0 +/- 0.2, mean age 55.6 +/- 1.0 years) and
assess their value in predicting variceal bleeding and death during a mean
follow-up of 19.3 +/- 1.5 months. Baseline CPS correlated with hepatic
venous pressure gradient (HVPG) (p = 0.001), azygos blood flow (p <
0.05), cardiac index (p < 0.05), and inversely with mean arterial
pressure (p < 0.01) and systemic vascular resistance index (p <
0.05). Renal blood flow was not related to any haemodynamic parameter or
CPS. Thirty-eight patients died during follow-up, and 16 had a variceal
bleed. Death (p = 0.001) and variceal bleeding (p < 0.05) were more
likely in patients with HVPG > 16 mmHg than in those with HVPG < 16
mmHg, and variceal bleeding was more likely in patients with HVPG > 12
mmHg (vs. HVPG < 12 mmHg, p < 0.05). HVPG also predicted death and
variceal haemorrhage on univariate and multivariate analyses. No other
haemodynamic parameter predicted death or bleeding. In alcoholic cirrhosis,
severity of liver disease is related to HVPG, collateral blood flow and
degree of systemic circulatory abnormalities. HVPG is a useful predictor of
survival and variceal bleeding in these patients.
相似文献
994.
Enhanced nitric oxide release during cortical spreading depression following infusion of glyceryl trinitrate in the anaesthetized cat 总被引:2,自引:0,他引:2
SJ Read MI Smith AJ Hunter AA Parsons 《Cephalalgia : an international journal of headache》1997,17(3):159-165
Intravenous infusion of glyceryl trinitrate (GTN) into migraineurs induces an immediate headache followed by migraine. We studied the effect of GTN 10.25 g kg1 min 1 ) on local cerebrovascular laser Doppler flux (rCBFLDF ), artery diameter and NO concentration (selective NO microelectrode) in the pial middle cerebral artery perfusion territory of the anaesthetized cat, at rest and during cortical spreading depression (SD). GTN infusion induced a significant increase in pial artery diameter, rCBFLDF , and NO concentration. Following termination of infusion, NO concentrations remained significantly elevated above controls for 60 min, other parameters returned to baseliae within 10 min ( p 0.05, ANOVA, post hoc Dunnett's multiple comparison procedure). Two hours after termination of infusion KCl-evoked SD was initiated. GTN-treated animals exhibited significantly ( p 0.05, Kruskal-Wallis) elevated SD-induced NO release compared to controls. All other parameters remained unaffected. Our results demonstrate that GTN induces a prolonged increase in local NO concentrations and enhances SD-induced NO release. 相似文献
995.
Furosemide inhibits regenerative cortical spreading depression in anaesthetized cats 总被引:2,自引:0,他引:2
SJ Read MI Smith CD Benham AJ Hunter AA Parsons 《Cephalalgia : an international journal of headache》1997,17(8):826-832
Ionic perturbations occur during cortical spreading depression (SD), a phenomenon implicated in migraine pathophysiology. We studied the effect of 0.2,2 and 20 mg kg−1 iv ( n =4) furosemide on cortical direct current (d.c.) potential, cerebrovascular laser Doppler flux (rCBFLDF ), artery diameter and NO concentration in the parietal cortex of the anaesthetized cat during repetitive SD. In vehicle treated animals ( n =4), SD activity was sustained for 50 1.8 min. However, duration of SD activity was significantly reduced when compared to vehicle to 39 6.6 ( n =4), 3.1 8.3 ( n =4) and 27.3 11.3 min ( n =4), at 0.2, 2 and 20 mg kg−1 iv furosemide respectively. It is hypothesized that the mechanism of inhibition of SD d.c. activity by furosemide may be through alterations in cortica ion buffering capacity or inhibition of cell swelling in neurones or glia. These mechanisms may represent potential novel drug targets in future migraine therapy. 相似文献
996.
EL Blundell ; DH Pamphilon ; ID Fraser ; JE Menitove ; TJ Greenwalt ; EL Snyder ; AJ Repucci ; SL Hedberg ; JK Anderson ; DH Buchholz ; LR Kagen ; RH Aster 《Transfusion》1996,36(4):296-302
BACKGROUND: Irradiation of platelet concentrates (PCs) with ultraviolet- B (UVB) light inactivates the contaminating white cells and might be an alternative to filtration for the prevention of alloimmunization to HLA antigens and subsequent refractoriness to further platelet transfusions in multiply transfused patients with bone marrow failure. STUDY DESIGN AND METHODS: Patients with hematologic malignancy, mainly acute myeloid leukemia, were prospectively assigned in a random manner to receive either UVB-irradiated or control, nonirradiated PCs. All patients were given red cells that were white cell reduced by filtration. Transfusion efficacy and alloimmunization were assessed by means of corrected count increments, requirement for red cells and PCs, and measurement of lymphocyte-reactive antibodies. RESULTS: UVB-irradiated PCs had a clinical efficacy similar to controls as judged by corrected count increments at 1 to 6 and 12 to 24 hours and by the median requirement for red cell and platelet transfusions. Alloimmunization determined by measurements of lymphocyte-reactive antibodies using both conventional and antiglobulin-augmented lymphocytotoxicity techniques was not abolished in recipients of UVB-irradiated PCs (4/30, 13%) but was less than that in controls (5/20, 25%; p = NS). The mean number of platelet transfusion episodes prior to the occurrence of alloimmunization was greater in the control group (27 vs. 10; p = 0.017). CONCLUSION: In this trial, UVB irradiation did not diminish the clinical efficacy of platelet transfusions. There was a small but nonsignificant reduction alloimmunization, but no difference in refractoriness of the two groups was observed. Larger prospective randomized studies are required to confirm these findings and to compare UVB irradiation with white cell reduction. 相似文献
997.
Antineutrophil cytoplasmic autoantibodies (ANCA) have been described in sera of patients with several forms of systemic vasculitis, including Wegener's granulomatosis and microscopic polyarteritis. The two main targets of ANCA in vasculitis are proteinase 3 (PR3) and myeloperoxidase (MPO). ANCA are capable of activating neutrophils primed by tumor necrosis factor-alpha (TNF-alpha) in vitro, which may be relevant for the induction of the vascular inflammation observed in vivo. Recently, it has been suggested that engagement of Fc gamma receptor IIa (Fc gamma RIIa) on the neutrophils is involved in the activation by ANCA. In the present study, we show that activation of the neutrophil respiratory burst by anti-PR3 and anti-MPO is strongly enhanced after TNF priming and lost on removal of the Fc parts of the antibodies. Similar results were obtained when the neutrophils were activated with antibodies against known membrane antigens without major changes in the expression of the target antigens. The TNF-induced enhancement of the neutrophil activation was not observed when adherence of the cells was prevented by continuous stirring of the suspension or by the addition of CD18 antibodies before TNF exposure. Hence, our results indicate that engagement of both Fc gamma RIIa and beta 2 integrins is instrumental in neutrophil activation induced by ANCA. 相似文献
998.
We present cell cycling and functional evidence that the CD34+CD38- immunophenotype can be used to define a rare and primitive subpopulation of progenitor cells in umbilical cord blood. CD34+CD38- cells comprise 0.05% +/- 0.08% of the mononuclear cells present in cord blood. Cell cycle analysis with the fluorescent DNA stain 7- aminoactinomycin D showed that the percentage of CD34+ cells in cycle directly correlated with increasing CD38 expression. CD34+CD38- cord blood cells were enriched for long-term culture-initiating cells (LTCIC; cells able to generate colony-forming unit-cells [CFU-C] after 35 to 60 days of coculture with bone marrow stroma) relative to CD34+CD38- cells. In an extended LTCIC assay, CD34+CD38- cells were able to generate CFU-C between days 60 and 100, clearly distinguishing them from CD34+CD38+ cells that did not generate CFU-C beyond day 40. When plated as single cells, onset of clonal proliferation was markedly delayed in a subpopulation of CD34+CD38- cells; clones (defined as > 100 cells) appeared after 60 days of culture in 2.9% of CD34+CD38- cells. In contrast, 100% of CD34+CD38+ cells formed clones by day 21. Although the CD34+CD38- immunophenotype defines highly primitive populations in both bone marrow and cord blood, important functional differences exist between the two sources. CD34+CD38- cord blood cells have a higher cloning efficiency, proliferate more rapidly in response to cytokine stimulation, and generate approximately sevenfold more progeny than do their counterparts in bone marrow. 相似文献
999.
To better understand the limited hematopoietic life span of human marrow "Dexter" cultures, we developed a miniaturized, two-stage culture system with which in vitro production of hematopoietic progenitors could be reproducibly detected and quantified. Light- density, gradient-separated human marrow cells were inoculated into Leighton slide tubes, and adherent ("stromal") cell layers were allowed to develop on the removable coverslips within these tubes during an initial 4 weeks of culture. Once stromal cell layers were established, cultures were irradiated (800 cGy) to eliminate all residual hematopoietic progenitors. The cultures were then recharged with autologous, cryopreserved marrow cells (enriched for BFU-E and CFU-GM) to reconstitute stem cell populations and to initiate in vitro hematopoiesis. Most progenitor cells added to irradiated cultures were no longer detectable by clonal assays within one to four days after recharge. Nonetheless, stable populations of adherent BFU-E and CFU-GM became established in these cultures within 24 to 48 hours, and when the total numbers of progenitors (adherent and nonadherent) were measured at weekly intervals thereafter, it was evident that both BFU-E and CFU-GM were generated in vitro. However, progenitor cell production declined as neutrophils and macrophages accumulated in the cultures. Moreover, with this accumulation of mature myeloid cells, increasing levels of O2- and H2O2 could be detected in the cultures, and it was found that the addition of oxidant scavengers (catalase and mannitol) to culture media enhanced the weekly expansions of progenitor cell numbers that could be measured. These findings support the conclusion that reactive O2 intermediates generated by mature myeloid cells have a role in limiting the duration and extent of hematopoietic progenitor cell self-renewal in long-term "Dexter" cultures of human marrow. 相似文献
1000.
Oral iloprost in Raynaud's phenomenon secondary to systemic sclerosis: a multicentre, placebo-controlled, dose-comparison study 总被引:3,自引:2,他引:3
Black CM; Halkier-Sorensen L; Belch JJ; Ullman S; Madhok R; Smit AJ; Banga JD; Watson HR 《Rheumatology (Oxford, England)》1998,37(9):952-960
OBJECTIVE: To identify the optimal dose of oral iloprost on the basis of
efficacy and tolerability in patients with Raynaud's phenomenon secondary
to systemic sclerosis. DESIGN: Multicentre, randomized, parallel-group
comparison of two different doses of oral iloprost and placebo. SETTING:
European university hospitals. PATIENTS: A total of 103 patients with
Raynaud's phenomenon secondary to systemic sclerosis. INTERVENTION:
Patients received one of three treatments for 6 weeks: placebo, oral
iloprost 50 microg or oral iloprost 100 microg. Each treatment was taken
twice daily, giving total daily doses of iloprost of 100 and 200 microg.
MEASUREMENTS: The frequency, total daily duration and severity of Raynaud's
attacks were recorded in a specially designed patient diary; physician's
global assessment and adverse events were recorded at visits to the clinic.
Analysis was performed on an intention-to-treat population. RESULTS: A
total of 103 patients were recruited, 89 completed the assessments
throughout the treatment period and 82 completed an additional 6 weeks of
follow-up after treatment. Thirty-five patients received placebo, 33
received iloprost 50 microg and 35 received iloprost 100 microg. The mean
percentage reductions in the frequency, total daily duration and severity
of Raynaud's attacks were numerically greater in the iloprost groups at the
end of treatment and at the end of follow-up. At the end of treatment (6
weeks), there were significant treatment differences in the total daily
duration of attacks (P = 0.03), but not in the severity (P = 0.07) or the
frequency of attacks (P = 0.37). At the end of follow-up (12 weeks), there
were significant treatment differences in the total daily duration of
attacks (P = 0.001) and in the severity of attacks (P = 0.007), but not in
the frequency of attacks (P = 0.07). Percentages of patients improved at
the end of treatment as assessed by the physician were 44% placebo, 57%
iloprost 50 microg and 64% iloprost 100 microg (not significant).
Side-effects were reported by 80% of patients on placebo, 85% on oral
iloprost 50 microg and 97% on oral iloprost 100 microg. Premature
discontinuations of treatment in each group were 9, 30 and 51%,
respectively, with 6, 27 and 51% being due to adverse events. CONCLUSION:
The results on the daily duration of Raynaud's attacks suggest that both 50
and 100 microg oral iloprost twice daily may be effective in the treatment
of Raynaud's phenomenon secondary to systemic sclerosis. The 50 microg
iloprost dose was better tolerated in this patient group.
相似文献