全文获取类型
收费全文 | 847篇 |
免费 | 66篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 31篇 |
妇产科学 | 5篇 |
基础医学 | 67篇 |
口腔科学 | 25篇 |
临床医学 | 49篇 |
内科学 | 115篇 |
皮肤病学 | 3篇 |
神经病学 | 6篇 |
特种医学 | 9篇 |
外国民族医学 | 1篇 |
外科学 | 421篇 |
综合类 | 48篇 |
预防医学 | 39篇 |
药学 | 74篇 |
中国医学 | 7篇 |
肿瘤学 | 16篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 31篇 |
2020年 | 20篇 |
2019年 | 24篇 |
2018年 | 32篇 |
2017年 | 36篇 |
2016年 | 21篇 |
2015年 | 28篇 |
2014年 | 33篇 |
2013年 | 73篇 |
2012年 | 30篇 |
2011年 | 55篇 |
2010年 | 37篇 |
2009年 | 57篇 |
2008年 | 45篇 |
2007年 | 36篇 |
2006年 | 36篇 |
2005年 | 36篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 13篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有923条查询结果,搜索用时 215 毫秒
31.
输血后肝炎患者HCV感染及其病毒血症的研究 总被引:4,自引:0,他引:4
利用血清学ELISA方法和PCR技术对169例输血后肝炎(PTH)患者病因学进行了研究。结果表明,PTH的主要致病原为HCV(98.22%),其中部分患者(24/169),同时合并有HBV感染,3例PTH患者病因仍不明确,HCV感染所致PTH患者抗HCV检出时间为PTH症状出现后7d~1年,平均为54.62d,HCVRNA在感染早期(6~20d)即可检出,对84例PTH患者1.5年~3年的随访观察 相似文献
32.
Internalization of the PTH type I receptor (PTH1R) is regulated in a cell- and ligand-specific manner. We previously demonstrated
that the sodium/proton exchanger regulatory factor type 1 (NHERF1; EBP50) is pivotal in determining the range of peptides
that internalize the PTH1R. Antagonist PTH fragments can internalize the PTH1R in some kidney and bone cell models. PTH(7-34),
which binds to, but does not activate, the PTH1R, internalizes the PTH1R in kidney distal tubule (DT) cells, where NHERF1
is not expressed. The effect of antagonist PTHrP peptides has not, to this point, been assessed. PTH1R internalization was
measured by real-time confocal fluorescence microscopy of DT cells stably expressing 105 EGFP-tagged PTH1R/cell (1). PTHrP(7-34) internalized the PTH1R in a manner indistinguishable from PTH(7-34). Introduction of NHERF1 into DT cells, however,
blocked PTH(7-34)—, but not PTHrP(7-34)—, induced PTH1R internalization. To delineate the sequences within PTHrP that determine
whether PTH1R internalization is affected by NHERF1, chimeric PTH/PTHrP fragments were tested for their ability to induce
PTH1R internalization. PTH(7-21)/PTHrP (22-34), PTH(7-32)/PTHrP(33-34), and PTH(7-33)/PTHrP(34) at 1 μM each internalized the PTH1R 50–70% in a NHERF1-independent manner. When the C terminus of PTHrP was replaced with homologous
amino acids from PTH, NHERF1 inhibited PTH1R internalization. It was determined that simply mutating F34 to A in PTH induced
PTH1R internalization in a NHERF1-independent manner. None of the chimeric peptides activated the PTH1R but all effectively
competed for 1 nM PTH(1-34) in cyclic AMP assays. In addition, all chimeric peptides competed for radiolabeled PTH(1-34) in binding assays
in DT cells. PTH(1-34) and PTHrP(7-34), but not PTH(7-34), efficiently recruited β-arrestin1 to plasma membrane PTH1Rs. We,
therefore, conclude that PTH(1-34) and PTHrP(7-34) induce a conformational change in the PTH1R that promotes arrestin binding
and dissociates NHERF1 from PTH1R internalization. 相似文献
33.
P. Baur V. Daniel S. Pomer H. Scheurlen G. Opelz D. Roelcke 《Annals of hematology》1991,62(2-3):68-73
Summary The hepatitis C-virus (HCV) is the main etiologic agent of posttransfusion hepatitis (PTH). Most patients depending on hemodialysis need transfusion of blood before kidney transplantation. Of 272 patients after kidney transplantation, 27 (10%) were found to be anti-HCV-ELISA-positive (HCV-Antibody-ELISA, Ortho Diagnostics). The antibodies could be neutralized by HCV C-100-3 antigen. Eight of 22 patients (36%) who had more than one kidney transplantation were classified anti-HCV positive [30% (8/27) of all anti-HCV positive patients]. The number of transfused blood units ranged from 0 to 99 BU. Receiving more than one kidney graft or the transfusion of more than 5 units of blood increased the risk for HCV infection 3.5 or 4.1 times, respectively, compared with one transplantation or less than 5 units of blood. No significant interactions were seen between these two variables. Of the anti-HCV positive patients, 48% were anti-HBc negative as well as HBs-antigen negative, 52% were anti-HBc positive.Abbreviations A492
absorbance at 492 nm wave-length
- ALT
alanin-amino-transferase
- BU
blood units
- D
dichotomization
- HBV
Hepatitis B-Virus
- HNANB
Hepatitis non-A, non-B
- OR
odds ratio
- PTH
posttransfusion hepatitis
- s/co
mean A492/cutoff= ELISA-ratio
- TPL
transplantation 相似文献
34.
Sergi G Sarti S Mosele M Ruggiero E Imoscopi A Miotto F Bolzetta F Inelmen EM Manzato E Coin A 《Experimental gerontology》2011,46(11):929-933
Background
Inflammatory states, hypovitaminosis D and secondary hyperparathyroidism may have a role in the age-related loss of muscle mass, and physical performance in healthy old people. The aim of this study is to investigate changes in muscle mass, strength and physical performance in healthy, active elderly females over a 3-year follow-up, correlating them with any inflammatory states and PTH and 25-hydroxyvitamin D (25-OHD) levels.Methods
One hundred healthy females over 65 years of age routinely attending a twice-weekly mild fitness program were eligible for the study. Clinical history, serum parameters, body composition by DEXA, handgrip strength, knee extensor isometric/isotonic strength and functional performance measured using the Short Physical Performance Battery (SPPB) were evaluated at the baseline and after 3 years.Results
After 3 years, the women had a significant decrease in weight (?:−0.8 ± 3.1 kg; p < 0.05) and height (?:−0.4 ± 0,6 cm; p < 0.001), while their BMI and body composition parameters did not change. Only IL-6 (?: 0.6 ± 2.0; p < 0.01) and PTH (?: 30.7 ± 29.2 ng/L; p < 0.001) increased significantly, while there were no changes in 25-OHD levels. There was a significant decrease in all the SPPB results and in muscle strength. ? PTH only correlated with the variation in 4-meter walking speed (r: 0.41; p < 0.01).Conclusions
With advancing age, physical performance declines even in healthy, active females despite a spare of muscle mass. The increase in PTH seems to have a role in this decline, that could be clarified by further investigations. 相似文献35.
36.
Stanislas Czekalski Nadine Loreau Franoise Paillard Raymond Ardaillou Jean-Paul Fillastre Eric Mallet 《European journal of clinical investigation》1974,4(2):85-92
Abstract. Biologically active bovine parathyroid hormone (b PTH) 1–34 fragment infused over one hour in normal subjects produced an immediate and sharp increase in the excreted fractions of filtered bicarbonate, sodium and potassium, followed by the return to pre-infusion levels as soon as the administration of b PTH was stopped. There was a gradual but steady increase in the excreted fraction of filtered phosphate but a decrease in the excreted fraction of filtered calcium and magnesium. The excreted fractions of these ions were still abnormal 150 minutes after the completion of PTH infusion. The urinary excretion of 3′5′-cyolic AMP increased immediately about one hundred-fold but returned rapidly to pre-infusion levels. Urinary clearance of cyclic AMP approximated glomerular filtration rate in control periods and was twenty to thirty times greater during b PTH infusion. In subjects overloaded with bicarbonate, b PTH brought about a decrease in bicarbonate Tm and the same effects on the urinary excretion of other electrolytes. 3′5′-cyclic AMP excretion was clearly higher in control periods and reached higher levels during b PTH infusion when compared to subjects without an alkaline load. 3′5′-cyclic AMP excretion and fractional clearance were also clearly higher in subjects not given b PTH when control periods were compared to periods with bicarbonate infusion or after acetazolamide administration. During distal blockade obtained by simultaneous administration of chlorothiazide and ethacrynic acid, there was a delay in the rise of 3′5′-cyclic AMP excretion after b PTH administration. It can be concluded from these studies that the pattern of excretion of 3′5′-cyclic AMP is similar to that of bicarbonate, sodium and potassium. The increase of 3′5′-cyclic AMP excretion when urinary pH is above 7 suggests a diffusion trapping mechanism for the secretion into the lumen of this nucleotide. Distal diuretics used in distal blockade did not inhibit 3′5′-cyclic AMP production but delayed its secretion into urine. 相似文献
37.
Background
The purpose of this study was to determine if laterality of internal jugular vein (IJV) sampling affects the accuracy of intraoperative parathyroid hormone (PTH) monitoring during parathyroidectomy for primary hyperparathyroidism.Methods
In this study, 109 patients underwent parathyroidectomy (82 with unilateral disease, 27 with multigland disease). PTH samples were taken from both the left and the right IJV at these time points: preincision (baseline) and then at 5, 10, and, in selected patients, 20 minutes after excision. The Miami criterion was used to determine operative success.Results
In all 109 patients combined, the mean decreases in intraoperative PTH levels were 73.8 ± 22.2% for the left IJV and 71.9 ± 23.0% for the right IJV (P = .22). The Miami criterion was met in 105 patients: in 100 (95%) left IJV samples and 99 (94%) right IJV samples (P = 1.00).Conclusions
No difference was found in the accuracy of intraoperative PTH monitoring between patients' left and right IJV samples. Central venous laterality did not affect fulfillment of the Miami criterion. 相似文献38.
《Nutrition, metabolism, and cardiovascular diseases : NMCD》2014,24(12):1310-1316
Background and aimsA high circulating fibroblast growth factor 23 (FGF23) level is an independent risk factor for cardiovascular mortality in renal transplant recipients and the general population. N-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) may contribute to cardiovascular risk reduction. We investigated whether fish and EPA-DHA intake are related to FGF23 levels in renal transplant recipients.Methods and resultsWe performed a cross-sectional analysis in 619 stable renal transplant recipients (mean age 53 years, 57% male, estimated glomerular filtration rate [eGFR] 53 ± 20 mL/min/1.73 m2). Dietary intake was assessed by a 177-item food frequency questionnaire. Serum intact FGF23 was measured by ELISA. We examined differences in FGF23 levels across categories of fish and EPA-DHA intake using analysis of variance models adjusted for age, sex, dietary and lifestyle factors and key determinants of FGF23. Patients consumed on average 15 g of fish and 139 mg EPA-DHA/day. Median FGF23 was 62 pg/mL (IQR 43–98 pg/mL). Higher dietary EPA-DHA and fish intake were associated with lower serum FGF23 levels. Subgroup analyses revealed that particularly in patients with reduced renal function (eGFR <60 mL/min/1.73 m2), adjusted FGF23 levels (114, 79, 75 pg/mL, P = 0.0001) were inversely associated with tertiles of EPA-DHA intake. Similarly, we observed an inverse association between fish consumption and serum FGF23 levels in adjusted analyses.ConclusionA higher intake of fish and dietary n-3 fatty acids (EPA-DHA) is related to lower circulating FGF23 levels in renal transplant recipients. Further research is needed to assess the causality of this association and the clinical implications. 相似文献
39.
目的利用基于荧光共振能量转移(Fluorescence resonance energy transfer,FRET)技术的检测PKC激活或PKC-delta激活的报告分子来确定PTH是否可以通过PLC非依赖途径激活PKC和PKC-delta。方法将表达PKC激活报告分子(CKAR)的质粒和表达PKC-delta激活报告分子的质粒转染HEK293细胞,培养72h后通过共聚焦显微镜检测FRET的改变,并以此判断佛波酯(TPA)是否激活PKC和PKC-delta。将表达甲状旁腺素1型受体(PTHR1)的质粒与CKAR质粒或PKC-delta质粒共转染HEK293细胞,培养72h后通过共聚焦显微镜检测FRET的改变,并判断PTH(1-34)、G1R19(1-34)和0.1%的三氟乙酸(TFA)对PKC和PKC-delta的作用。结果在转染CKAR质粒或PKC-delta质粒的HEK293细胞,TPA均使青色荧光与黄色荧光的强度之比(C/Y)增加。在共转染PTH1R质粒与CKAR质粒或PKC-delta质粒的HEK293细胞,PTH(1-34)和G1R19(1-34)均增加了C/Y的值,而0.1%TFA未引起C/Y的改变。结论 PTH与PTHR1结合后通过PLC非依赖途径激活PKC/PKC-delta。 相似文献
40.
Birgit Mair Stefan Tangl Johannes Feierfeil Daniela Skiba Georg Watzek Reinhard Gruber 《Clinical oral implants research》2009,20(4):400-405
Objective: Aging is a physiological determinant that can distinguish the outcome of a pharmaceutical therapy to improve osseointegration of titanium implants. Here we examined the possible interaction of intermittent parathyroid hormone (PTH) and the age of the recipient on the parameters of osseointegration in a rat tibia implantation model.
Material and methods: Twenty female Wistar rats aged 8 months and 20 female rats aged 2 months received PTH at 60 μg/kg body weight or a vehicle by a subcutaneous injection three times a week. After 4 weeks, histomorphometric analysis of the peri-implant area was performed. The possible interaction of the two factors on 'bone volume per tissue volume' (BV/TV) and 'bone-to-implant contact' (BIC) was tested by two-way analysis of variance.
Results: Based on data from the medullary compartment, two-way analysis of variance revealed that the effect of 'intermittent PTH' depends on the 'age of the recipient' when BV/TV is considered the dependent variable ( P =0.04). Post hoc tests indicated that PTH leads to an increase of BV/TV of adult and young rats. However, when BIC was considered the dependent variable, no interaction was observed ( P =0.14). PTH but not aging has a significant impact on BIC. In the cortical compartment, no effects of PTH on osseointegration were observed.
Conclusions: The findings indicate that treatment with PTH is more effective on the peri-implant bone regeneration in adult than in young animals, supporting the importance to consider the influences of age on the development of pharmaceutical therapies to increase the process of osseointegration. 相似文献
Material and methods: Twenty female Wistar rats aged 8 months and 20 female rats aged 2 months received PTH at 60 μg/kg body weight or a vehicle by a subcutaneous injection three times a week. After 4 weeks, histomorphometric analysis of the peri-implant area was performed. The possible interaction of the two factors on 'bone volume per tissue volume' (BV/TV) and 'bone-to-implant contact' (BIC) was tested by two-way analysis of variance.
Results: Based on data from the medullary compartment, two-way analysis of variance revealed that the effect of 'intermittent PTH' depends on the 'age of the recipient' when BV/TV is considered the dependent variable ( P =0.04). Post hoc tests indicated that PTH leads to an increase of BV/TV of adult and young rats. However, when BIC was considered the dependent variable, no interaction was observed ( P =0.14). PTH but not aging has a significant impact on BIC. In the cortical compartment, no effects of PTH on osseointegration were observed.
Conclusions: The findings indicate that treatment with PTH is more effective on the peri-implant bone regeneration in adult than in young animals, supporting the importance to consider the influences of age on the development of pharmaceutical therapies to increase the process of osseointegration. 相似文献