全文获取类型
收费全文 | 1824篇 |
免费 | 90篇 |
国内免费 | 13篇 |
学科分类
医药卫生 | 1927篇 |
出版年
2023年 | 19篇 |
2022年 | 31篇 |
2021年 | 54篇 |
2020年 | 25篇 |
2019年 | 42篇 |
2018年 | 54篇 |
2017年 | 31篇 |
2016年 | 49篇 |
2015年 | 48篇 |
2014年 | 79篇 |
2013年 | 105篇 |
2012年 | 110篇 |
2011年 | 128篇 |
2010年 | 92篇 |
2009年 | 90篇 |
2008年 | 115篇 |
2007年 | 103篇 |
2006年 | 101篇 |
2005年 | 88篇 |
2004年 | 67篇 |
2003年 | 86篇 |
2002年 | 59篇 |
2001年 | 57篇 |
2000年 | 33篇 |
1999年 | 43篇 |
1998年 | 24篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 19篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1965年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有1927条查询结果,搜索用时 0 毫秒
101.
We report the successful outcome of allogeneic stem cell transplant (SCT) in a patient with acute lymphoblastic leukaemia (ALL) and pulmonary zygomycosis diagnosed prior to transplant. The lesion was surgically excised and SCT proceeded with antifungal therapy, granulocyte transfusions and G-CSF support during the period of neutropenia. 相似文献
102.
Webb JT Pilmanis AA Kannan N Olson RM 《Aviation, space, and environmental medicine》2000,71(7):692-698
INTRODUCTION: Space Shuttle extravehicular activity (EVA) requires decompression from sea level pressure (14.7 psia) to a 4.3 psia (30,300 ft) pressure suit. The transition currently involves altering the shuttle atmosphere to allow shirt-sleeve denitrogenation to occur during a 12 to 36-h staged decompression (SD) at 10.2 psia (9,800 ft) with an oxygen-enriched breathing gas (26.5% oxygen, 73.5% nitrogen). The denitrogenation provides protection from decompression sickness (DCS) during EVA in a 4.3 psia pressure suit. Our goal was to determine the highest altitude at which SD while breathing 100% oxygen (SD100) could provide effective protection from development of DCS symptoms after further decompression to 29,500 ft (4.5 psia). METHODS: There were 30 male subjects exposed to at least 6 of 11 conditions in random order on successive months to 29,500 ft for 4 h while performing mild exercise and being monitored for venous gas emboli (VGE) with an echo-imaging system. The subjects received 15 min of ground-level (GL) preoxygenation and an additional 60 or 120 min of SD100 at one of four altitudes between 8,000 ft (10.9 psia) and 18,000 ft (7.3 psia). Control exposures followed a 75- or 135-min ground-level preoxygenation. RESULTS: During SD100, one case of DCS occurred at 18,000 ft, but not at lower staging altitudes. Higher levels of VGE were observed during SD100 at 18,000 ft than during SD100 at any lower altitude. CONCLUSION: Staged decompression at 16,000 ft and below results in decompression risk during subsequent decompression to 29,500 ft similar to that following equivalent periods of ground-level preoxygenation. 相似文献
103.
Jha N Kannan AT Paudel IS Niraula S 《The Southeast Asian journal of tropical medicine and public health》2001,32(3):547-552
A number of surveys, small or large, have been undertaken by various agencies for coverage evaluation of immunization programs. The most commonly used design is the WHO-30 cluster sampling method. Other new methods are the Institute for Refresh Medical Statistics (IRMS) New Delhi method and the lot quality assurance sampling method. This paper describes the National Immunization Day (NID) method to evaluate the immunization coverage of the Expanded Program on Immunization (EPI) vaccines in the Sunsari district of Nepal. A total number of 3,332 respondents (69.4% females and 30.6% males) were interviewed regarding the immunization status of their children during NID. The children with complete immunization (BCG, measles and three doses of DPT and OPV) were 65.7%. The individual coverage by EPI vaccines (except OPV III and measles) was more than 80%. The result shows that there is positive relationship between immunization coverage and educational level of the respondents. 相似文献
104.
Effects of halothane on sarcoplasmic reticulum calcium release channels in porcine airway smooth muscle cells 总被引:6,自引:0,他引:6
BACKGROUND: Volatile anesthetics relax airway smooth muscle (ASM) by altering intracellular Ca2+ concentration ([Ca2+]i). The authors hypothesized that relaxation is produced by decreasing sarcoplasmic reticulum Ca2+ content via increased Ca2+ "leak" through both inositol trisphosphate (IP3) and ryanodine receptor channels. METHODS: Enzymatically dissociated porcine ASM cells were exposed to acetylcholine in the presence or absence of 2 minimum alveolar concentration (MAC) halothane, and IP3 levels were measured using radioimmunoreceptor assay. Other cells were loaded with the Ca2+ indicator fluo-3 and imaged using real-time confocal microscopy. RESULTS: Halothane increased IP3 concentrations in the presence and absence of acetylcholine. Inhibition of phospholipase C blunted the IP3 response to halothane. Exposure to 2 MAC halothane induced a transient [Ca2+]i response, suggesting depletion of sarcoplasmic reticulum Ca2+. Exposure to 20 microM Xestospongin D, a cell-permeant IP3 receptor antagonist, resulted in a 45+/-13% decrease in the [Ca2+]i response to halothane compared with halothane exposure alone. In permeabilized cells, Xestospongin D or 0.5 mg/ml heparin decreased the [Ca2+]i response to halothane by 65+/-13% and 68+/-22%, respectively, compared with halothane alone. In both intact and permeabilized cells, 20 microM ryanodine blunted the [Ca2+]i response to halothane by 32+/-13% and 39+/-21%, respectively, compared with halothane alone. Simultaneous exposure to Xestospongin D and ryanodine completely inhibited the [Ca2+]i response to halothane. CONCLUSIONS: The authors conclude that halothane reduces sarcoplasmic reticulum Ca2+ content in ASM cells via increased Ca2+ leak through both IP3 receptor and ryanodine receptor channels. Effects on IP3 receptor channels are both direct and indirect via elevation of IP3 levels. 相似文献
105.
KB Reddy VK Ahuja V Kannan E Vallikad N Anantha 《Journal of Medical Imaging and Radiation Oncology》1997,41(3):262-265
A retrospective analysis of 22 patients with ovarian dysgerminoma who were treated between 1980 and 1987 was carried out. The median age at presentation was 24.5 years. A total of 15 patients were in stage I, one patient was in stage II and six patients were in stage III. Bilateral ovarian involvement was present in four patients. Conservative surgery was carried out in nine patients and 11 patients underwent radical surgery. Two patients had biopsy only. Fourteen patients received adjuvant radiotherapy and three patients received salvage radiation for recurrent disease. The 10-year actuarial survival rate was 81.8%. All 15 patients in stage I were alive and disease-free at a median follow-up of 125 months. Four patients (one in stage II and three in stage III) died of progressive or recurrent abdominopelvic disease. Pelvic recurrence occurred after conservative surgery in two patients in stage IA who had a tumour size greater than 10 cm, but they were salvaged with radical surgery, chemotherapy and radiotherapy. There were seven patients aged 20 years or less. All were alive and disease-free at a median follow-up of 127 months. 相似文献
106.
107.
BACKGROUND: The growth of patients > or =65 years on hemodialysis is increasing. Guidelines recommend arteriovenous fistula (AVF) access but their outcomes in elderly patients are controversial. This study compared the outcomes of AVF in patients <65 years old (65- group) versus those > or =65 years old (65+ group). METHODS: This retrospective analysis of prospectively collected data included 444 incident, first-time AVF created in a large dialysis center between January 1, 1995 and July 1, 2003. The primary outcome of AVF cumulative patency was evaluated using Kaplan-Meier survival analysis with log-rank test comparison. A Cox model determined factors associated with AVF loss. RESULTS: One hundred ninety-six patients (44%) were in the 65+ group. In total, there were 230 (52.2%) radiocephalic, 186 (42.2%) brachiocephalic, and 25 (5.6%) basilic vein transposed AVF. The one-year AVF cumulative survival was 75.1% (65+ group) and 79.7% (65- group); the five-year survival was 64.7% (65+ group) and 71.4% (65- group). The overall total procedure, angioplasty, thrombolysis, and revision rates per access-year were 0.83, 0.30, 0.66, and 0.16, respectively. The 65+ group had a relative risk of 1.7 of their AVF failing to mature compared with the 65- group. Multivariate analysis yielded these variables significant for AVF loss: male sex HR 0.63 (95% CI 0.44-0.91), coronary artery disease HR 2.1 (95% CI 1.5-3.0), and Caucasian ethnicity HR 0.63 (95% CI 0.44-0.91). CONCLUSION: Age should not be a limiting factor when determining candidacy for AVF creation due to equivalent survival and procedural rates. Failure of fistula maturation is a primary concern to patients of all ages and demands further study. 相似文献
108.
BACKGROUND: Metabolic acidosis is a major metabolic abnormality in end-stage renal disease (ESRD) and alkali is provided with dialysis treatment to patients on chronic peritoneal dialysis (CPD) to keep their acid-base balance within normal serum HCO3- levels. METHODS AND RESULTS: We examined the levels of venous serum HCO3- in 163 patients on CPD and the predictive factors for HCO3- levels low enough to indicate metabolic acidosis. The mean value for HCO3- was 26+/-2.4 mmol/l and for anion gap was 13.1+/-3.1 mEq/l. A serum bicarbonate concentration of less than 24 mmol/l, compatible with metabolic acidosis, was observed in 13.5% of the patients. In a multivariate analysis HCO3- levels were directly correlated with older age and use of CaCO3- as phosphate binders, and inversely associated with serum potassium, the use of sevelamer and low lactate dialysis solutions. Higher serum urea levels, the use of low lactate solutions and sevelamer instead of CaCO3 were significantly predictive factors for HCO3- levels < 24 mmol/l. CONCLUSIONS: Venous HCO3- and anion gap values were within the normal ranges in stable CPD patients. In 13.5% of them, however, chronic metabolic acidosis was observed based on venous HCO3- levels < 24 mmol/l. Dietary protein intake, the use of sevelamer and low (35 mmol/l) concentration of lactate in dialysis solutions are important predictive factors for chronic metabolic acidosis in these patients. 相似文献
109.
Scaffolds of pure hydroxyapatite suitable for either direct clinical use or tissue-engineering applications were successfully produced via hydrothermal transformation of aragonite, obtained from fresh cuttlefish bones, at 200°C followed by sintering. Beyond low production cost, worldwide availability and natural–biological origin of raw materials, the produced scaffolds have ideal pore size and interconnectivity features suitable for supporting biological activities, such as bone tissue growth and vascularization. Bioactivity in vitro tests were excellent: (a) rapid and pronounced formation of hydroxyapatite occurred when the scaffolds were immersed in simulated body fluid (SBF), and (b) outstanding proliferation of osteoblasts was registered. The produced scaffolds can be machined and shaped very easily at any stage of processing. Therefore, these ceramic scaffolds can satisfy both bioactivity demands and the requirements for shaping of tailor-made individualized implants, especially for randomly damaged bones. 相似文献
110.