首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   283篇
  免费   23篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   12篇
妇产科学   3篇
基础医学   27篇
口腔科学   24篇
临床医学   33篇
内科学   64篇
皮肤病学   8篇
神经病学   4篇
特种医学   68篇
外科学   25篇
综合类   5篇
预防医学   14篇
眼科学   2篇
药学   4篇
肿瘤学   14篇
  2023年   1篇
  2021年   1篇
  2020年   4篇
  2019年   5篇
  2018年   7篇
  2017年   3篇
  2016年   4篇
  2015年   8篇
  2014年   6篇
  2013年   10篇
  2012年   4篇
  2011年   4篇
  2010年   15篇
  2009年   13篇
  2008年   4篇
  2007年   7篇
  2006年   6篇
  2005年   8篇
  2004年   2篇
  2003年   2篇
  2002年   1篇
  2001年   4篇
  2000年   3篇
  1999年   8篇
  1998年   20篇
  1997年   17篇
  1996年   16篇
  1995年   12篇
  1994年   10篇
  1993年   10篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1989年   13篇
  1988年   7篇
  1987年   4篇
  1986年   7篇
  1985年   5篇
  1984年   4篇
  1983年   7篇
  1982年   6篇
  1981年   10篇
  1980年   6篇
  1979年   3篇
  1978年   4篇
  1977年   5篇
  1976年   4篇
  1975年   4篇
排序方式: 共有308条查询结果,搜索用时 15 毫秒
61.
鉴定γB-晶体蛋白非酶糖基化位点。方法用离子交换HPLC纯化小牛晶状体γB-晶体蛋白,与果糖保温后用糜蛋白酶水解。糖基化的肽用Affi-Gel601柱层析纯化,并用RP-HPLC分离各肽。  相似文献   
62.
There is evidence that endogenous opioid peptides exert an inhibitory effect on pituitary luteinizing hormone (LH) secretion both in animals and in humans, by interacting with mu-opioid receptors. However, a role for delta-opioid receptors in the regulation of gonadotrophin releasing hormone (GnRH) secretion has recently been suggested. In the present study, we evaluated the effect of the highly selective delta-opioid receptor agonist deltorphin on the LH and follicle stimulating hormone (FSH) responses to naloxone in six healthy fertile women during the luteal phase of the menstrual cycle. Deltorphin infusion alone (7 microg/kg/min for 60 min) did not significantly change the basal serum concentrations of LH in this group of women. The intravenous (i.v.) bolus administration of naloxone (15 mg) induced a significant (P < 0.001) increase in serum LH concentrations (from a mean basal value of 4.24+/-1.10 IU/l to a peak of 13.27+/-1.8 IU/l). The LH response to naloxone was significantly (P < 0.001) blunted by preinfusion of deltorphin (13.27+/- 1.80 IU/l versus 4.80+/-1.18 IU/l). No significant changes in FSH concentrations were observed during deltorphin, naloxone or deltorphin plus naloxone administration. These data indicate that activation of delta-opioid receptors can reduce naloxone-induced LH release, suggesting a possible role of delta receptors in opioidergic modulation of LH secretion in women.   相似文献   
63.
BACKGROUND: Human red cells containing inositol hexaphosphate (IHP) have a lowered O2 affinity, though they are able to bind and carry about the same amount of oxygen as native cells. These modified cells therefore deliver oxygen more efficiently to the tissues, which is a property of potential clinical utility. Investigators set out to devise a system and procedure by which large volumes of IHP-containing red cells, suitable for transfusion, could be produced quickly and efficiently. STUDY DESIGN AND METHODS: The encapsulation of IHP into human red cells by use of several variations of static electroporation was performed to define the conditions necessary for optimal IHP incorporation and cell survival. These conditions were used as a starting point for optimization of a flow electroporation system. RESULTS: When fresh human red cells in a 35 mM IHP solution are subjected to three exponential pulses of field strength of 2.98 +/− 0.064 kV per cm per pulse and pulse length of 2.0 +/− 0.2 msec per pulse while flowing through a cooled electroporation chamber, the condition of the resultant cells, according to the criteria used here, is optimized. After storage for 24 hours in plasma at 37 degrees C, the cells show more than 85-percent survival (in vitro) and hematologic indices nearly identical to those of unpulsed control cells. The p50 value of these cells, however, has doubled to 50.4 +/− 2.0 torr. The processing time for 1 unit of blood is 90 minutes. CONCLUSION: These data indicate that the system described here can efficiently produce low-oxygen-affinity red cells in volumes that are useful in clinical applications.  相似文献   
64.
Abnormal fetal and infant growth have increasingly been correlated with adult onset cardiovascular disease. To date, there is little known about the lipid fatty acid profiles in infant cardiovascular tissue. Therefore, we analysed total lipid fatty acids from thoracic and abdominal aorta intima and media from 24 normally grown sudden infant death syndrome cases. Aorta from small for gestational age (n = 2), failure to thrive from birth (n = 3), and premature (n = 1) infants were also examined. Dihomo-gamma-linolenic acid (C20:3n-6) and oleic acid (C18:1n-9) concentrations were significantly lower in the thoracic than in the abdominal aorta. Similar dietary related differences were found in the subgroup (n = 15) of infants fed on formula milks. Both abdominal and thoracic intimal arachidonic (C20:4n-6) to dihomo-gamma-linolenic acid ratios were greater in the infants with retarded growth after birth than in their normally grown counterparts. Growth restriction in infancy might disrupt the normal accretion of vascular endothelial polyunsaturated fatty acids.  相似文献   
65.
For a seven year period (1985-91) clinical and epidemiological data were prospectively collected on children aged < 10 years with microbiologically confirmed invasive Haemophilus influenzae type b infection in the Oxford region to study the epidemiology of the disease and determine the potential impact of early primary immunisation in infants. Computer records of primary immunisations given to these cases were retrospectively analysed and, where necessary, hospital and general practitioner records were searched to determine the immunisation history. Over the seven year period, 416 cases of invasive H influenzae type b disease were reported. Widescale immunisation against H influenzae type b began in 1991 as part of a regional trial. The estimated annual incidence for invasive disease between 1985 and 1990 was 35.5 cases per 100,000 children aged less than 5 years; for H influenzae type b meningitis it was 25.1 per 100,000 children aged less than 5 years. The cumulative risks for invasive disease and meningitis by the fifth birthday were one in 560 and one in 800 respectively. The majority of disease (71%) occurred in children less than 2 years of age with the peak monthly incidences at 6 and 7 months of age. The overall mortality was 4.3% and 50% of these deaths occurred suddenly. Most (91%) of the children had received at least one primary immunisation against diphtheria, tetanus, and pertussis before H influenzae type b infection and there was only one case of parental refusal of immunisation. None had received H influenzae type b immunisation. Given a vaccine uptake of 90% by 5 months of age it is estimated that at least 82% of the H influenzae type b infections could have been prevented. Extrapolated nationally, 1150 cases of infection and 50 deaths could be prevented each year by routine primary immunisation.  相似文献   
66.
We randomly selected twenty lead workers from an electric accumulator factory in the State of S?o Paulo, Brazil, whose blood lead level and urinary d-aminolevulinic acid level were below 60 mg/dL and 10 mg/L, respectively. The workers were submitted to a standard motor nerve conduction velocity study of the right radial nerves, in addition to blood lead dosage. Based on these measures, a first-order linear regression model was adjusted, where the dependent variable was conduction velocity and the independent variable was the blood lead level. Analyzing the fitted model, we inferred that the negative predictive value of the Brazilian biological exposure limit is 0.63. In order for the above biological exposure limit to have a negative predictive value of 0.99, the study suggests that it be reduced from its present value (60 mg/dL) to 32 mg/dL.  相似文献   
67.
There is a dearth of published data regarding the presence of post-transplant donor-specific antibodies (DSA), especially C1q-binding DSA (C1q+DSA), and patient and kidney allograft outcomes in simultaneous liver–kidney transplant (SLKT) recipients. We conducted a retrospective cohort study consisted of 85 consecutive SLKT patients between 2009 and 2018 in our center. Associations between presence of post-transplant DSA, including persistent and/or newly developed DSA and C1q+DSA, and all-cause mortality and the composite outcome of mortality, allograft kidney loss, and antibody-mediated rejection were examined using unadjusted and age and sex-adjusted Cox proportional hazards and time-dependent regression models. The mean age at SLKT was 56 years and 60% of the patients were male. Twelve patients (14%) had post-transplant DSA and seven patients (8%) had C1q+DSA. The presence of post-transplant DSA was significantly associated with increased risk of mortality (unadjusted model: Hazard Ratio (HR) = 2.72, 95% confidence interval (CI): 1.06–6.98 and adjusted model: HR = 3.20, 95% CI: 1.11–9.22) and the composite outcome (unadjusted model: HR = 3.18, 95% CI: 1.31–7.68 and adjusted model: HR = 3.93, 95% CI: 1.39–11.10). There was also higher risk for outcomes in recipients with C1q+DSA compared the ones without C1q+DSA. Post-transplant DSA is significantly associated with worse patient and kidney allograft outcomes in SLKT. Further prospective and large cohort studies are warranted to better assess these associations.  相似文献   
68.
69.
Lian  EC; Savaraj  N 《Blood》1981,58(2):354-359
Antiplatelet drugs have been used in the treatment of thrombotic thrombocytopenic purpura (TTP) but there in vivo efficacy remains controversial. It has been shown that, in vitro, the plasmas obtained from patients with TTP induced the aggregation of washed platelets from normal donors as well as patients in remission. The effects of platelet inhibitors on the TTP plasma-induced platelet aggregation were examined. It was found that aspirin, indomethacin, ibuprofen, sulfinpyrazone, 5, 8, 11, 14-eisacotetraynoic acid, prostaglandin E1, prostaglandin I2, dBcAMP, apyrase, creatine phosphate/creatine phosphokinase, antimycin, 2-deoxy-D-glucose, dipyridamole, clofibrate, dextran 40, dextran 70, dibucaine, xylocaine, methylmaleimide, and ethylenediamine tetraacetic acid had little or no effect at all. These data lead us to conclude that at least in certain cases, antiplatelet drugs probably play a limited role in the treatment of patients with TTP.  相似文献   
70.
Pairs of sequential perfusion lung scans and pulmonary angiograms obtained in 45 patients were reviewed to investigate the utility of short-term, sequential scintigraphy in the diagnosis of pulmonary embolism (PE). Forty-six sequential scan pairs were reviewed; 13 were ventilation-perfusion (V-P) pairs. Angiograms were obtained within 48 hours of either the first (65%) or second (35%) perfusion scan in each pair. Sequential scintigraphic patterns were classified as showing change (i.e., improvement in defects, new defects), no change, or as being indeterminate. A changing perfusion pattern was associated with a high (20/23) likelihood of PE, but seven of 16 patients with stable perfusion patterns also had PE. The sensitivity of a changing perfusion pattern for PE was 0.74 (20/27) and its specificity was 0.75 (9/12). In two of six patients who had serial V-P studies that showed changing perfusion defects, there were matched changes in regional ventilation and angiograms were negative. The findings suggest that short-term serial perfusion lung scanning may aid the scintigraphic diagnosis of PE in certain circumstances. Serial V-P imaging is needed, however, to maximize diagnostic specificity.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号