全文获取类型
收费全文 | 635篇 |
免费 | 48篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 57篇 |
妇产科学 | 6篇 |
基础医学 | 36篇 |
口腔科学 | 19篇 |
临床医学 | 66篇 |
内科学 | 96篇 |
皮肤病学 | 1篇 |
神经病学 | 32篇 |
特种医学 | 142篇 |
外科学 | 101篇 |
综合类 | 44篇 |
预防医学 | 36篇 |
眼科学 | 3篇 |
药学 | 23篇 |
肿瘤学 | 13篇 |
出版年
2021年 | 4篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 25篇 |
2012年 | 17篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 19篇 |
1998年 | 32篇 |
1997年 | 38篇 |
1996年 | 35篇 |
1995年 | 30篇 |
1994年 | 31篇 |
1993年 | 20篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1970年 | 8篇 |
1969年 | 6篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有690条查询结果,搜索用时 15 毫秒
21.
22.
A study was conducted on the phosphorylation of proteins in the neutrophil cytosol in response to phorbol myristate acetate (PMA) and N- formyl-methionyl-leucyl-phenylalanine (fMLP). Autoradiography of gel electrophoretograms prepared from neutrophils incubated with 32Pi in the presence and absence of the activators showed nine proteins whose state of phosphorylation was affected by neutrophil activation. 32P was gained by eight of these proteins and was lost by the ninth. For all but one of these proteins, the change in the extent of labeling appeared to reach completion by one to two minutes. It was possible to quantitate the changes in 32P content of three of the nine proteins. One of these was the 20-kD protein that lost label when the neutrophils were activated. Quantitation showed that over half the 32P present in this protein in the resting state was gone within 0.2 minutes after activation. The other two were proteins weighing 11 and 69 kD. The phosphorylation characteristics of these two proteins differed, depending on whether activation had been carried out with PMA or fMLP. These differences in protein phosphorylation support other evidence suggesting that PMA and fMLP do not activate neutrophils by identical biochemical pathways. Differences in phosphorylation between resting and activated cells were not affected by dibutyryl cyclic guanosine monophosphate (cGMP), dibutyryl cyclic adenosine monophosphate (cAMP), theophylline, aspirin, hydrocortisone, or colchicine. The differences were abolished, however, by 30 mumol/L trifluoperazine. This finding is consistent with the hypothesis that the calcium/calmodulin system plays a biochemical role in the activation of neutrophils. 相似文献
23.
Arellano R Gan BS Salpeter MJ Yeo E McCluskey S Pinto R Irish J Ross DC Doyle DJ Parkin J Brown D Rotstein L Witterick I Matthews W Yoo J Neligan PC Gullane P Lampe H 《Anesthesia and analgesia》2005,100(6):1846-1853
In Canada, hydroxyethyl starch 264/0.45 (HES 264/0.45; molar weight 264 kDa, molar substitution 0.45) has largely replaced albumin as the colloidal fluid of choice for perioperative intravascular volume expansion. The maximum recommended dose of HES 264/0.45 is 28 mL/kg; however, there are no clinical data supporting this limit. In this study we compared the hemostatic effects of HES 264/0.45 versus 5% albumin in doses up to 45 mL/kg over 24 h during major reconstructive head and neck surgery. Fifty patients were randomized to receive HES 264/0.45 or 5% human albumin from the induction of anesthesia until 24 h thereafter. Both albumin and HES 264/0.45 effectively maintained physiologic variables in the perioperative and postoperative periods. The partial thromboplastin time and international normalized ratio were significantly increased in the HES 264/0.45 group compared with the albumin group after infusion of 30 mL/kg and 45 mL/kg (P < 0.05). Factor VIII activity and von Willebrand factor level were significantly reduced in the HES 264/0.45 group compared with the albumin group after infusion of 15 mL/kg, 30 mL/kg, and 45 mL/kg (P < 0.05). Significantly more subjects in the HES 264/0.45 group received allogeneic red blood cell transfusions (P < 0.02). We conclude that HES 264/0.45 infusions >30 mL/kg over 24 h impair coagulation to a greater extent than albumin, possibly leading to more allogeneic transfusions. 相似文献
24.
OBJECTIVES: To investigate the relationship of specific nutrients and food items with oral precancerous lesions among tobacco users.
DESIGN: A population-based case-control study. SETTING: Villages in Palitana taluk of Bhavnagar district, Gujarat, India.
SUBJECTS AND METHODS: An interviewer-administered food frequency questionnaire, developed and validated for this population, was used to estimate nutrient intake in blinded, house-to-house interviews. Among 5018 male tobacco users, 318 were diagnosed as cases. An equal number of controls matched on age (±5 years), sex, village, and use of tobacco were selected.
MAIN OUTCOME MEASURES: Odds ratios (OR) from multiple logistic regression analysis controlling for relevant variables (type of tobacco use and economic status).
RESULTS: A protective effect of fibre was observed for both oral submucous fibrosis (OSF) and leukoplakia, with 10% reduction in risk per g day-1 ( P < 0.05). Ascorbic acid appeared to be protective against leukoplakia with the halving of risk in the two highest quartiles of intake (versus the lowest quartile: OR = 0.46 and 0.44, respectively; P < 0.10). A protective effect of tomato consumption was observed in leukoplakia and a suggestion of a protective effect of wheat in OSF.
CONCLUSION: In addition to tobacco use, intake of specific nutrients may have a role in the development of oral precancerous lesions. 相似文献
DESIGN: A population-based case-control study. SETTING: Villages in Palitana taluk of Bhavnagar district, Gujarat, India.
SUBJECTS AND METHODS: An interviewer-administered food frequency questionnaire, developed and validated for this population, was used to estimate nutrient intake in blinded, house-to-house interviews. Among 5018 male tobacco users, 318 were diagnosed as cases. An equal number of controls matched on age (±5 years), sex, village, and use of tobacco were selected.
MAIN OUTCOME MEASURES: Odds ratios (OR) from multiple logistic regression analysis controlling for relevant variables (type of tobacco use and economic status).
RESULTS: A protective effect of fibre was observed for both oral submucous fibrosis (OSF) and leukoplakia, with 10% reduction in risk per g day
CONCLUSION: In addition to tobacco use, intake of specific nutrients may have a role in the development of oral precancerous lesions. 相似文献
25.
HE Connor W Feniuk DT Beattie PC North AW Oxford DA Saynor PPA Humphrey 《Cephalalgia : an international journal of headache》1997,17(3):145-152
The biological profile of naratriptan (N-methyl-3-(1-methyl-4-piperidinyl)-1H-indole-5-ethane-sulphona-mide), a novel 5HT1B/1D receptor agonist, was investigated in a variety of experimental models of relevance to migraine. Naratriptan has high affinity for human recombinant 5HT1B and 5HT1D receptors (pKi = 8.70.03 and 8.30.1, respectively) and causes contractions of dog isolated basilar and middle cerebral artery (EC50 values of 0.11 and 0.07 M, respectively). Naratriptan causes small contractions of human isolated coronary arteries (EC50 value of 0.17 M; maximum contraction equivalent to 33% of 5HT maximum). In anaesthetized dogs, naratriptan causes selective vasoconstriction of the carotid arterial bed (CD50 dose = 193 g kg−1 ) and, in anaesthetized rats, naratriptan selectively inhibits neurogenic plasma protein extravasation in the dura (ID50 = 4.1 g kg−1 ). In a variety of antinociceptive tests, naratriptan has no effect even at high doses. In conscious rats and dogs, naratriptan has high oral bioavailability (71% and 95%, respectively). The data show that naratriptan is a selective agonist at 5HT1B/1D receptors, with a pharmacological profile very similar to that of sumatriptan, albeit 2-3 fold more potent. These observations, coupled with high oral bioavailability in animals, suggest that naratriptan has the profile of an orally effective anti-migraine drug. 相似文献
26.
PC Ng J Hiu TF Fok EAS Nelson KL Cheung W Wong 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(8):955-956
We report an unusual case of localized congenital tuberculosis otitis in a preterm infant. Unlike disseminated congenital cases, the manifestations of localized otitis are associated with a triad of signs: (i) regional lymphadenopathy in the absence of typical systemic features of tuberculosis; (ii) delayed onset of presentation; and (iii) refractory otitis unresponsive to conventional antimicrobial agents. The need for greater diligence in looking for neonatal tuberculosis is emphasized, especially in an ethnic or socioeconomic environment where the disease is prevalent. Congenital tuberculosis, otitis, preterm
PC Ng, Department of Paediatrics, Level 6, Clinical Sciences Building, Prince of Wales Hospital, Shatin, NT, Hong Kong 相似文献
PC Ng, Department of Paediatrics, Level 6, Clinical Sciences Building, Prince of Wales Hospital, Shatin, NT, Hong Kong 相似文献
27.
Vaslef SN Knudsen NW Neligan PJ Sebastian MW 《The Journal of trauma》2002,53(2):291-5; discussion 295-6
BACKGROUND: Massive transfusion of blood products in trauma patients can acutely deplete the blood bank. It was hypothesized that, despite a large allocation of resources to trauma patients receiving more than 50 units of blood products in the first 24 hours, outcome data would support the continued practice of massive transfusion. METHODS: A retrospective review of charts and registry data of trauma patients who received over 50 units of blood products in the first day was conducted for a 5-year period at a Level I trauma center. Patients were stratified into groups on the basis of the number of transfusions received. Results are expressed as mean +/- SD. Univariate analysis and multivariate logistic regression were used to identify those risk factors determined in the first 24 hours after admission that were predictive of mortality. Physiologic differences between survivors and nonsurvivors were also examined. RESULTS: Of 7,734 trauma patients admitted between July 1, 1995, and June 30, 2000, 44 (0.6%) received > 50 units of blood products in the first day. Overall mortality in these patients was 57%. There was no significant difference (p = 0.565, chi2) in mortality rate between patients who received > 75 units of blood products in the first day versus those who received 51 to 75 units. Multiple logistic regression analysis identified only one independent risk factor, base deficit > 12 mmol/L, associated with mortality. Base deficit > 12 mmol/L increases the risk of death by 5.5 times (p = 0.013; 95% confidence interval, 1.44-20.95). Neither the total blood product transfusion requirement in the first day nor the packed red blood cell transfusion amount in the first day were significant independent risk factors. Causes of the 25 deaths in this series included exsanguination in the operating room (n = 1) or in the surgical intensive care unit (n = 12), multiple organ failure/sepsis (n = 3), head injury (n = 3), respiratory failure (n = 2), cerebrovascular accident (n = 1), and other (n = 3). Of the survivors, 63% were discharged to home, 21% to rehabilitation, 11% to nursing home, and 5% to another acute care facility. Of the nonsurvivors, the mean Injury Severity Score was 43, 88% had a base deficit > 12 mmol/L, 68% had a Glasgow Coma Scale score < 8, and 64% had a Sequential Organ Failure Assessment score > 10. CONCLUSION: The 43% survival rate in trauma patients receiving > 50 units of blood products warrants continued aggressive transfusion therapy in the first 24 hours after admission. 相似文献
28.
Norton KI Kattan M Rao JS Cleveland R Trautwein L Mellins RB Berdon W Boechat MI Wood B Meziane M Platzker AC;P 《AJR. American journal of roentgenology》2001,176(6):1553-1558
OBJECTIVE: We prospectively studied children with and without maternally transmitted HIV-1 infection born to mothers infected with HIV-1 to determine the incidence of chronic radiographic lung changes (CRC) and to correlate these changes with clinical assessments. SUBJECTS AND METHODS: Between 1990 and 1997, we scored 3050 chest radiographs using a standardized form. Group I children (n = 201) were HIV-1-infected at enrollment. Group II children (n = 512) were enrolled prenatally or before 28 days postpartum and subsequently subdivided into group IIa (n = 86), children identified as HIV-1-infected; and group IIb (n = 426), those who were HIV-1-uninfected. CRC were defined as parenchymal consolidations or nodular disease lasting 3 months or more or increased bronchovascular markings or reticular densities lasting 6 months or more. Morbidity was assessed by CD4 counts, viral load, the presence of low oxygen saturation, wheezing, tachypnea, crackles, and clubbing. RESULTS: The cumulative incidence of chronic radiographic lung changes in HIV-1-infected children was 32.8% by 4 years old, with increased bronchovascular markings or reticular densities being most common. Chronic changes were associated with lower CD4 cell counts and higher viral loads. Resolution of these chronic changes was associated with decreasing CD4 cell counts but not with lower rates of clinical findings, viral load, or difference in survival. CONCLUSION: With increased survival, CRC are becoming more common. The resolution of these changes may indicate immunologic deterioration rather than clinical improvement. 相似文献
29.
Biomarkers for lysosomal storage disorders: identification and application as exemplified by chitotriosidase in Gaucher disease 总被引:1,自引:0,他引:1
Johannes M Aerts Marielle J van Breemen Anton P Bussink Karen Ghauharali Richard Sprenger Rolf G Boot Johanna E Groener Carla E Hollak Mario Maas Suzanne Smit Huub C Hoefsloot Age K Smilde Johannes PC Vissers Sheryas de Jong Dave Speijer Chris G de Koster 《Acta paediatrica (Oslo, Norway : 1992)》2008,97(S457):7-14
30.
Wang JF; Bashir M; Engelsberg BN; Witmer C; Rozmiarek H; Billings PC 《Carcinogenesis》1997,18(2):371-375
Chromium (Cr) is a human carcinogen and a potent DNA damaging agent.
Incubation of DNA with CrCl3 resulted in dose-dependent binding of Cr to
DNA and, at concentrations >20 microM, altered the electrophoretic
mobility of a 100 bp oligonucleotide. We also demonstrate that high
mobility group (HMG) proteins 1 and 2 bind Cr-damaged DNA (Cr-DNA). Protein
binding was lesion density-dependent, with maximal binding to DNA treated
with 100 microM CrCl3. HMG2 binds to Cr-DNA with a calculated Kd of
approximately 10(-9) M. These proteins also bound DNA obtained from
chromate-treated cells. These results suggest that the covalent attachment
of Cr to DNA induces alterations in DNA structure which are recognized by
HMG1 and HMG2. Therefore, these proteins may function as Cr-damaged DNA
recognition proteins in vivo and as a consequence of binding, may play a
role in directing the cellular response to Cr-DNA adduct formation.
相似文献