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   1058篇
  免费   78篇
  国内免费   17篇
耳鼻咽喉   3篇
儿科学   81篇
妇产科学   29篇
基础医学   89篇
口腔科学   26篇
临床医学   71篇
内科学   177篇
皮肤病学   27篇
神经病学   20篇
特种医学   135篇
外科学   129篇
综合类   134篇
预防医学   69篇
眼科学   4篇
药学   53篇
中国医学   39篇
肿瘤学   67篇
  2023年   8篇
  2022年   15篇
  2021年   23篇
  2020年   20篇
  2019年   15篇
  2018年   20篇
  2017年   14篇
  2016年   19篇
  2015年   29篇
  2014年   43篇
  2013年   38篇
  2012年   47篇
  2011年   47篇
  2010年   76篇
  2009年   64篇
  2008年   27篇
  2007年   29篇
  2006年   40篇
  2005年   29篇
  2004年   16篇
  2003年   22篇
  2002年   13篇
  2001年   15篇
  2000年   11篇
  1999年   21篇
  1998年   46篇
  1997年   61篇
  1996年   51篇
  1995年   38篇
  1994年   32篇
  1993年   31篇
  1992年   13篇
  1991年   8篇
  1990年   13篇
  1989年   23篇
  1988年   20篇
  1987年   17篇
  1986年   17篇
  1985年   10篇
  1984年   10篇
  1983年   2篇
  1982年   9篇
  1981年   8篇
  1980年   11篇
  1979年   3篇
  1977年   6篇
  1976年   6篇
  1975年   2篇
  1958年   4篇
  1957年   2篇
排序方式: 共有1153条查询结果,搜索用时 0 毫秒
61.
This randomized controlled trial was designed to answer the question: does administration of dexamethasone to neonates with bronchopulmonary dysplasia decrease the need for assisted ventilation? Twenty-five infants with a birth weight < 1501 g, requiring mechanical ventilation and FiO2 of ± 0.30 at 21-35 days of age, were randomized to treatment with iv dexamethasone or to sham injections for 12 days. The primary outcome criterion was extubation within seven days after study entry. Treatment (n= 12) and control (n= 13) groups were well matched at entry. Dexamethasone facilitated weaning from assisted ventilation (p= 0.0154). There was no increased incidence of infection. Dexamethasone treatment resulted in a significant increase in glucosuria (p= 0.0002) and in systolic blood pressure (p= 0.0034). There was a significant decrease in heart rate (p= 0.0001) and a significant weight loss (p= 0.0002) following dexamethasone treatment. Dexamethasone treatment facilitated weaning from assisted ventilation but several systemic effects were noted that deserve further evaluation before dexamethasone becomes routine treatment.  相似文献   
62.
The effects of intermittent positive airway and continuous negative extrathoracic pressure ventilation on cerebral blood volume in preterm infants were studied using near infrared spectroscopy. In 12 infants continuous negative extrathoracic pressure caused a median decrease in cerebral blood volume of 0.14ml/100ml brain (95% confidence intervals (CI) 0.035–0.280) compared with no respiratory support. Oxygenated and deoxygenated haemoglobin also decreased, implying increased venous drainage as the main effect. In 17 infants intermittent positive pressure ventilation also caused a median reduction in cerebral blood volume of 0.06 ml/100 ml brain (95% CI 0.010–0.115) compared with endotracheal positive airway pressure. Deoxygenated haemoglobin increased by 0.07 ml/100 ml brain (95% CI 0.010–0.100) while oxygenated haemoglobin decreased by O.lOml/lOOml brain (95% CI 0.005–0.175). The increase in deoxygenated haemoglobin implies decreased venous drainage and the decrease in oxygenated haemoglobin implies that other factors may also be significant. Heart rate, blood pressure and oxygen saturation were monitored continuously and remained stable.  相似文献   
63.
目的:通过对突发性聋病人血中一氧化氮(NO)、丙二醛(MDA)、超氧化物歧化酶(SOD)含量的检洲,探讨突聋与血氧自由基和自由基的清除剂SOD之间的关系。方法:采用硝酸还原酶法测定了30例突聋病人血中NO含量,并以25例同期体检正常的健康人为对照组;同时还用硫代巴比妥酸比色法测定MDA含量,用黄嘌呤氧化酶法测定SOD含量。砖呆;应用金纳多、能量合剂、克林臭(即马来酸桂哌齐特,钙通道阻滞药)联合静脉输入,突聋各组的听力均有不同程度提高,有效率在78.57%以上。治疗后同对照组相比,血清NO、MDA水平明显低于患病之初,而SOD活性明显高于治疗之前,P〈0.01。结论;检测突聋病人血中N0、MDA、SOD的含量,能帮助我们探讨突聋的发病机理,估计预后。血氧自由基的升高可能是突聋发病因素之一,而SOD的含量可以帮助我们估计预后。  相似文献   
64.
Primary osteogenic sarcoma of the skull is an exceedingly rare condition. An adult male patient is described, who had a painless swelling in the right forehead that had rapidly enlarged in the previous 6 months. Radiological investigations showed a large destructive mass lesion involving the right side of the frontal bone with extension into the frontal sinus, causing marked extradural compression of brain parenchyma. Histopathological examination confirmed the lesion to be primary osteogenic sarcoma.  相似文献   
65.
目的研究全反式维甲酸(ATRA)及联合应用神经营养因子(BDNF,GDNF)对体外培养的神经干细胞(NSCs)分化的影响。方法取新生SD大鼠的前脑室下带(SVZ)区,按NSCs的常规培养方法分离、培养。用免疫细胞化学法鉴定巢蛋白(nestin)、微管相关蛋白-2(MAP-2)、胶质原纤维酸性蛋白(GFAP)的表达,以此来观察ATRA、BDNF、GDNF单独或联合应用对次代神经球细胞分化的作用。结果原代及次代神经球均显示nestin阳性,并可分化为MAP-2阳性神经元样细胞及GFAP阳性胶质细胞样细胞。1μmol/LATRA可促进NSCs分化为MAP-2阳性细胞的比例达(29.14&#177;5.00)%,显著高于对照组的(7.19&#177;1.21)%,差异有高度统计学意义(P〈0.001)。ATRA联合应用10ng/ml的BDNF或GDNF,与单独使用ATRA比较,并不显著提高NSCs分化为MAP-2阳性细胞的比例。结论ATRA可促进神经干细胞向神经元方向分化,ATRA联合应用BDNF或GDNF无明显的协同作用。  相似文献   
66.
The relations between age, metabolic control, disease adjustment, and psychological factors in boys and girls with recently diagnosed insulin-dependent diabetes mellitus (IDDM) were studied. Older girls had significant higher postremission glycosylated haemoglobin A (Hb Alc) levels ( p = 0.008). Girls with more hospitalizations had a lower developmental level ( p = 0.05), and had significantly more problems in the behavioural rating ( p = 0.05). Boys with more hospitalizations had a more external locus of control ( p = 0.01), more difficulties with disease adjustment, more emotional problems, and were also clinically assessed as having more behavioural problems. Boys showing more difficulties in psychological adjustment to the disease also had higher postremission Hb A1clevels ( p = 0.02). Although Swedish children with IDDM of short disease duration do not differ from healthy children in important psychological aspects, older girls and a small group of problematic younger boys are at risk of developing metabolic imbalance after a short disease duration.  相似文献   
67.
Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months.  相似文献   
68.
BACKGROUND: A major cause of the pelvic morbidity after a radical hysterectomy (RH) is thought to be damage to the pelvic nerve plexus, but direct evidence is lacking. We set out to determine the nerve content of the uterosacral ligaments (USLs) and cardinal ligaments (CLs) at the level at which they are divided during a radical hysterectomy and a simple hysterectomy. METHODS: Intraoperative cross-sectional biopsies were collected from the lateral third of the uterosacral ligaments (USLs) and cardinal ligaments (CLs) in 20 women undergoing radical hysterectomy (RH) and from the uterine insertion of these ligaments in 11 women undergoing a simple hysterectomy. Quantitative immunocytochemistry was utilized to demonstrate and quantify the nerve content of the uterine supporting ligaments at the level at which they are divided in a RH and in a simple hysterectomy. Indirect immunofluorescence staining of frozen cryostat sections was performed using primary antibodies to PGP 9.5 (a pan-neuronal marker). A computer-assisted image analyzer measured the percentage area of immunoreactivity (PAI) that was used to quantify the nerve density. Confocal microscopy was used to determine the composition and spatial arrangement of nerve fibers in the ligaments. RESULTS: The PAI was significantly greater in the RH biopsies than in the simple hysterectomy biopsies, for both the CLs (P < 0.001) and the USLs (P < 0.001). In the RH biopsies, more nerve tissue was present in the USL than CL (P = 0.01), and compared with the CL more of the nerve fibers in the USL were concentrated in large trunks. Excluding these trunks and autonomic ganglia, the free nerve content of the USL was lower than that of the CL (P < 0.001). The presence of nerve trunks, autonomic ganglia, and free nerve fibers within the lateral third of the USL and CL is consistent with extension of the inferior hypogastric plexus along these ligaments to the pelvic organs. CONCLUSIONS: The uterine supporting ligaments contain autonomic nerves and ganglia, as extensions of the inferior hypogastric plexus. The USLs have a greater nerve density than the CLs. Because RH disrupts more nerve tissue than a simple hysterectomy, these data provide further evidence for the neurogenic etiology of pelvic morbidity after RH.  相似文献   
69.
70.
Recent reports have demonstrated that the HIV-1 transactivator protein,tat, induces apoptosis in T-lymphocyte cell lines, as well as in peripheral blood mononuclear cells, and stimulates a cascade of events resulting in up-regulation of the potent immunosuppressive cytokine, transforming growth factor-β (TGF-β). In this study we evaluated the ability of TGF-β to mediatetat induced apoptosis in T-lymphocyte cell lines. T-cells treated exogenously with either TGF-β1 or a combination of tat and pan-specific TGF-β neutralizing antibodies showed little change in the amount of apoptosis. When treated with pan-specific TGF-β neutralizing antibodies, Jurkat cells that stably expresstat protein (Jurkat-tat) showed only a modest decrease in apoptosis, while CEM-TART cells (CEM T-cells expressing both HIV-1tat andrev) demonstrated little change in the amount of apoptosis. In conclusion, we have demonstrated that TGF-β does not play a significant role in mediatingtat induced T-cell apoptosis.  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