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   264篇
  免费   7篇
  国内免费   68篇
儿科学   6篇
妇产科学   4篇
基础医学   29篇
口腔科学   1篇
临床医学   61篇
内科学   52篇
皮肤病学   1篇
神经病学   24篇
特种医学   47篇
外科学   19篇
综合类   15篇
预防医学   15篇
眼科学   1篇
药学   53篇
肿瘤学   11篇
  2023年   1篇
  2022年   3篇
  2021年   2篇
  2020年   3篇
  2019年   5篇
  2018年   1篇
  2017年   2篇
  2016年   3篇
  2015年   1篇
  2014年   3篇
  2013年   12篇
  2012年   2篇
  2011年   5篇
  2010年   7篇
  2009年   12篇
  2008年   4篇
  2007年   49篇
  2006年   7篇
  2005年   15篇
  2004年   6篇
  2003年   13篇
  2002年   9篇
  2001年   6篇
  2000年   11篇
  1999年   10篇
  1998年   19篇
  1997年   17篇
  1996年   20篇
  1995年   15篇
  1994年   4篇
  1993年   6篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   14篇
  1988年   9篇
  1987年   6篇
  1986年   3篇
  1985年   1篇
  1984年   3篇
  1983年   3篇
  1980年   3篇
  1978年   2篇
  1977年   5篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
排序方式: 共有339条查询结果,搜索用时 0 毫秒
31.
The recent Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) reiterated long-standing recommendations that Stage 1 hypertension (BP ≥ 140/90 mm Hg) without comorbidity should be treated initially with diuretics (DI) or beta blockers (BB). Yet market research suggests that many physicians prefer to use other drug classes, such as calcium channel blockers and ACE inhibitors.
OBJECTIVES: To explore the determinants of therapeutic choice in hypertension.
METHODS: We surveyed by mail a stratified random sample of 10,000 U.S. cardiologists, internists, and family/general practitioners. Physicians were queried about their practice environment and their knowledge, attitudes, and practices regarding antihypertensive therapy, including their choice of drugs to treat patients with specified clinical profiles. The probability that physicians would follow JNC guidelines Stage 1 hypertension was analyzed using multiple logistic regression with stepwise backward elimination to select variable with p < 0.001.
RESULTS: Completed surveys were received from 1,023 physicians. 86.7% prescribe drug therapy for Stage 1 hypertension, and 19.5% (22.5% of drug prescribers) limit their choices to DI and BB. Guideline conformity was higher among physicians who: practice in academic medical centrers; are older; are general practitioners (versus general internists); have smaller caseloads; have fewer hypertensive patients; have higher proportions of HMO, Medicaid, and uninsured patients; and experience more formulary restrictions. Cardiologists and family practitioners were less likely than internists to follow guidelines.
CONCLUSION: JNC guidelines are better accepted by academic physicians, older physicians who have more expenence using DI and BB, physicians with smaller caseloads and hence more time for follow-up and therapy adjustment, and physicians who face drug reimbursement constraints.  相似文献   
32.
从秋季采收的菊科植物大丁草Gerbera anandria(L.)Sch Bip.全草中共分出十三种成分。本文报道其中三个新化合物的结构鉴定.它们分别是3,8-dihydroxy-4-methoxy-coumarin(ⅪⅩ),3,8-dihydroxy-4-methoxy-2-oxo-2 H-1-benzopyran-5-carboxylic acid(ⅩⅦ),和5,8-dihydroxy-7-(4-hydroxy-5-methyl-coumarin-3-)-coumarin(ⅩⅪ)。  相似文献   
33.
目的:观察橄榄叶提取物对白陶土及鹿角菜胶诱导的大鼠骨关节炎组织炎症的预防作用及对关节软骨的修复作用。方法:试验于2005-11/12在大连医科大学中日合作医药科学研究所进行。实验动物:选择健康雄性SD大鼠80只。实验材料:受试物橄榄叶提取物[由日本国Eisai食品与化学有限公司(日本国东京市)提供]。实验分组及给药:按体质量将大鼠随机分为5组,每组16只。模型对照组,灌胃给予蒸馏水,消炎痛组,灌胃给予消炎痛2mg/kg体质量,其余3组为橄榄叶提取物组,分别给予橄榄叶提取物(活性成分为以羟基酪醇为主的多酚)25,50,100mg/kg体质量灌胃,连续5d。第1天给药后1h,采用白陶土与鹿角菜胶诱发大鼠单发亚急性关节炎。实验评估:①诱发关节炎后1,3,5d,用容积测量法测定每组8只大鼠的左右后肢足跖体积,计算肿胀度,并同时用游标卡尺测定其胫跗骨关节最大径。②诱发关节炎后第5天,测定大鼠足跖伊文思蓝含量。每组的另8只大鼠,在诱发关节炎第5天麻醉后处死,剪下右足跖做组织病理学检查,观察橄榄叶提取物对大鼠骨关节炎中组织炎症的预防作用及对关节软骨的修复作用。结果:80只大鼠全部进入结果分析。①足跖肿胀度及胫跗骨关节径:诱发关节炎后1,3,5d,橄榄叶提取物50mg/kg组和100mg/kg组大鼠的右后足跖肿胀度均明显小于模型对照组大鼠[1d:(46.7±4.2)%,(44.8±6.8)%,(52.5±4.0)%;3d:(40.4±4.8)%,(37.4±5.7)%,(45.0±2.9)%;5d:(34.5±4.8),(31.7±5.3)%,(40.4±4.0)%,P<0.05],橄榄叶提取物25mg/kg体质量组,50mg/kg体质量组,100mg/kg体质量组大鼠的右后胫跗骨关节径与模型对照组大鼠比较差异无显著性(P>0.05)。②足跖伊文思蓝含量:诱发关节炎后第5天,橄榄叶提取物50mg/kg,100mg/kg组大鼠的右后足跖伊文思蓝含量均明显小于模型对照组大鼠(P<0.05)。③组织病理学检查及评分:组织病理学检查可见,与模型对照组比较,橄榄叶提取物50mg/kg组,100mg/kg组大鼠骨关节炎中组织炎症浸润明显减少,软骨组织无破坏,且组织病理学评分也明显小于模型对照组(P<0.05)。结论:橄榄叶提取物在50mg/kg体质量及以上剂量能有效地预防白陶土与鹿角菜胶诱发的大鼠骨关节炎中组织炎症,且对软骨有修复作用。  相似文献   
34.
目的:为评价三维超声心动图在心血管疾病中的应用前景,验证左室心肌质量对心血管事件和死亡发生的预测价值,应用三维超声心动图检测左室心肌质量,探讨左室心肌质量与心血管病患者远期预后的关系。方法:①超声测定:选择2003-10/2007-04武警医学院附属医院CCU及普通病房住院的64例患者接受左室心肌质量指数、静息左室射血分数测定和NYHA心脏功能分级的评估,仪器采用彩色多普勒超声诊断仪,型号为GE vivid-7。②分组及随访:根据左室肥厚标准和各参数平均数分为2组,左室心肌质量指数男性<131g/m2或女性<100g/m2为Ⅰ组,男性≥131g/m2或女性≥100g/m2为Ⅱ组,连续随访54个月,观察终点为心源性死亡。结果:61例进入结果分析。随访期末发现左室心肌质量指数与远期死亡有着显著的相关性(r=0.592,P=0.000);静息左室射血分数和NYHA心脏功能分级与死亡没有相关性(P>0.05);左室肥厚的Ⅱ组死亡例数多于Ⅰ组(P<0.01),两组的静息左室射血分数和NYHA心脏功能分级比较差异不显著(P>0.05);左室心肌质量指数高于平均数的Ⅱ组与Ⅰ组死亡相对危险比为2.56(95%CI),差异有统计学意义(P=0.020),但是静息左室射血分数和NYHA心脏功能分级之间死亡相对危险比没有统计学意义(P>0.05)。结论:①左室心肌质量与心血管病患者远期预后关系密切,可用于预测心源性死亡的发生情况。②三维超声心动图测定左室心肌质量及功能参数方便准确,可用于心功能定量评估。  相似文献   
35.

Background

Management of high-grade T1 (formerly T1G3) bladder cancer continues to be controversial. Should patients with T1G3 bladder cancer have an immediate radical cystectomy or should they receive intravesical bacillus Calmette-Guérin preserving bladder? Gemcitabine and cisplatin (GC) adjuvant chemotherapy may help to strike a balance between intravesical and early cystectomy. For purposes of this study, we continue to refer high-grade T1 lesion as “T1G3.”

Objective

To evaluate the characteristics and the long-term outcome of GC adjuvant chemotherapy in T1G3 bladder cancer after transurethral resection of bladder tumor (TURBT).

Materials and methods

We, retrospectively, reviewed 48 patients who were newly diagnosed with T1G3 bladder cancer between January 2009 and December 2012. A total of 48 patients received 4 cycles of GC adjuvant chemotherapy after TURBT. One month after 4 cycles of GC adjuvant chemotherapy, response was evaluated by re-TURBT. Median follow-up was 59.5 (range: 18–70) months, all patients have been observed for more than 3 years. Salvage cystectomy was recommended for patients with persistent disease and for tumor progression after initial complete response.

Result

Complete response was achieved in 44 (91.7%) patients. Of complete responders, 5 patients experienced recurrence and 5 patients showed progression. The progression rate and disease-specific survival rate were 10.4% and 91.7% at 3 years, respectively. More than 80% of survivors preserved their bladder. Kaplan-Meier curves showed that concomitant carcinoma in situ (CIS) was the only factor that had an influence on progression-free survival (P = 0.022) and disease-specific survival (P = 0.017). Concomitant CIS was the prognostic factor for progression rate and disease-specific survival rate at 3 years (P = 0.008 and P = 0.035).

Conclusion

GC adjuvant chemotherapy is a safe conservative treatment for T1G3 bladder cancer, but effective is really a phase II study. Patients with T1G3 bladder cancer with concomitant CIS should be treated more aggressively because of the high risk of progression.  相似文献   
36.
BACKGROUND: Testing for antibody to hepatitis B core antigen (anti-HBc) as a surrogate for hepatitis C viremia is no longer needed for blood donor screening. Currently, the important question is how much its use supplements hepatitis B surface antigen (HBsAg) donor screening in preventing transfusion-transmitted hepatitis B virus (HBV) infection. STUDY DESIGN AND METHODS: In a study conducted in the 1970s, 64 blood donors were associated with 15 cases of HBV (1.0%) in 1533 transfusion recipients. Sera from 61 donors at donation and 29 follow-up visits were available for present-day assays for HBsAg, HBV DNA, anti-HBc, and antibody to HBsAg (anti-HBs). RESULTS: HBsAg was found in four previously negative blood donors; HBV DNA was limited to three of these four. Anti-HBc was detected in six HBsAg-negative donors. Two other donors were negative in all assays at donation, but positive for anti- HBc and anti-HBs 2 to 4 months later. The remaining donors were negative for all HBV markers, which left five recipient cases unexplained. No HBV transmission was observed when anti-HBs sample-to- negative control values were > or = 10. CONCLUSION: Some 33 to 50 percent of cases of hepatitis B that could be transmitted by transfusion of blood from HBsAg-negative donors are prevented by anti- HBc screening. Anti-HBc-positive donors unequivocally positive for anti- HBs should be considered noninfectious for HBV and should be allowed to donate. Anti-HBc screening of paid plasmapheresis donors, supplemented by anti-HBs testing, would reduce the amount of HBV to be processed by virus inactivation and increase the content of anti-HBs in plasma pools.  相似文献   
37.
目的:为保护濒死心肌提供机会窗口,对比观察经冠脉移植自体骨髓单个核细胞或间充质干细胞后,实验性急性心肌梗死动物心功能变化及心肌组织核转录因子кB、心肌细胞凋亡情况。方法:实验于2005-03/2006-11在河北省人民医院实验中心完成。选用24只雄性冀中白猪,随机数字表法分为4组:正常对照组、模型组、单个核细胞组、间充质干细胞组,6只/组。①24只猪均以盐酸氯胺酮200mg臀部肌肉注射麻醉后,分别于各自右侧股骨抽取骨髓20mL,采用Fercoll法分离获得骨髓单个核细胞,加入胶体金溶液,培养12~16h待用。分离过程中取出含有骨髓单个核细胞成分的细胞层,常规培养传代,每3d换液1次,贴壁生长细胞即为骨髓间充质干细胞,加入胶体金溶液,培养24h待用。②除正常对照组外,其余各组均经导管球囊封闭第一对角支以远的前降支,复制猪急性心肌梗死模型。单个核细胞组、间充质干细胞组均于造模后立即开通前降支,分别经球囊注入预先分离的骨髓单个核细胞6×108个、间充质干细胞6×108个。模型组造模后于梗死1h开通前降支,经球囊注入磷酸盐缓冲液10mL。③各组分别于术前及术后4周经心脏超声检测心功能,取材行病理学检查、心肌组织核转录因子кB的免疫组织化学检测及心肌细胞凋亡检测。结果:24只雄性白猪均进入结果分析。①心功能变化:术前各组左心室收缩末内径、左心室舒张末内径、左心室射血分数、短轴缩短率基本相似。移植术后4周,正常对照组、单个核细胞组、间充质干细胞组左心室舒张末内径均明显低于模型组(F=4.68,P=0.01),左心室射血分数及短轴缩短率均明显高于模型组(F=5.14,P=0.01;F=3.32,P=0.04),各组左心室收缩末内径差异无显著性意义(F=1.64,P=0.21)。②心肌组织病理学改变:电镜下单个核细胞组、间充质干细胞组在梗死边缘区可见有胶体金颗粒的不成熟的心肌细胞,胞质中散在肌丝结构,肌丝排列紊乱不规则。③心肌组织核转录因子кB阳性率表达:与模型组比较,单个核细胞组、间充质干细胞组的梗死边缘区核转录因子кB阳性率明显降低(F=25.59,P=0.0001);正常心肌区核转录因子кB阳性率亦明显降低(F=18.20,P=0.0001)。④心肌细胞凋亡检测结果:与模型组比较,单个核细胞组、间充质干细胞组在心肌梗死区细胞凋亡率均明显降低(F=6.63,P=0.0027),梗死边缘区细胞凋亡率亦明显降低(F=36.07,P=0.0001)。正常心肌区单个核细胞组细胞凋亡率与模型组基本相似(F=9.69,P=0.004),但间充质干细胞组有所降低。⑤心功能与心肌细胞凋亡及心肌组织NF-кB的相关性:急性心肌梗死4周时,左心室射血分数与心肌细胞凋亡、心肌组织核转录因子кB均呈负相关(r=0.613,P=0.001;r=-0.437,P=0.033)。心肌细胞凋亡与心肌组织核转录因子кB呈正相关(r=0.672,P=0.002)。结论:经冠脉移植骨髓单个核细胞和间充质干细胞均可改善实验性急性心肌梗死动物的心功能,与梗死边缘区核转录因子кB表达降低及心肌细胞凋亡减少有关。骨髓单个核细胞移植的促血管增生作用优于间充质干细胞移植。  相似文献   
38.
目的:建立以晚期少突胶质细胞前体为主、与人类早产儿脑室周围白质软化病理相似的可靠动物模型。方法:实验于2005-10/2006-06在上海交通大学医学院附属新华医院科研中心完成。2d龄和7d龄SD同窝清洁级新生大鼠各43只,雌雄不拘,以随机数字表法分为4组,即2d龄模型组(n=25)、2d龄假手术组(n=18)、7d龄模型组(n=25)和7d龄假手术组(n=18),脑室周围白质软化动物模型建立:结扎双侧颈总动脉,手术时间短于10~15min,术后将新生大鼠送入缺氧箱缺氧30min,混合气体为体积分数0.08的O2和0.92的N2,输入流量为1~2.5mL/min。假手术组游离双侧颈总动脉,但不予结扎和缺氧。将各组大鼠分别于术后1d测定脑梗死体积,术后2d进行少突胶质细胞系列免疫组织化学染色分析、脑片TTC染色观察脑梗死情况以及光镜下脑病理研究,术后21d进行电镜下病理研究。结果:实验86只新生大鼠,14只制作脑室周围白质软化模型死亡,余72只计入统计。①术后1d各组脑片大体观察:模型组脑内呈现大面积白色梗死区,多为大脑前、中动脉供血区域,2,7d龄模型组梗死体积分别为(53.45±33.90),(68.78±20.22)mm3,梗死百分比分别为(24.98±15.44)%,(11.84±4.14)%;假手术组脑片颜色鲜红,未见白色梗死区。②新生大鼠少突胶质细胞系列标志物免疫组织化学结果:2d龄新生大鼠脑白质内以少突胶质细胞前体为主,7d龄新生大鼠则以成熟少突胶质细胞为主。模型大鼠的相应少突胶质细胞系列阳性标记物的积分吸光度值均显著低于同日龄对照新生大鼠(P<0.05~0.01)。③各组大鼠术后2d光镜下脑病理检查结果:2d龄模型组新生大鼠的脑室周围以及皮层下白质呈现囊性坏死和细胞凋亡,而皮质神经元损伤轻微;而7d龄模型组在白质和皮质部位均呈明显损伤。④术后21d电镜下各组幼鼠脑病理检查结果:2d龄模型组幼鼠的脑白质内未见髓鞘形成,7d龄模型组幼鼠中见少量髓鞘形成,而同日龄假手术对照幼鼠的脑白质内则髓鞘形成正常。结论:通过对2d龄新生大鼠双侧颈总动脉结扎伴缺氧30min缺氧缺血法创建的脑室周围白质软化新生大鼠模型中存在少突胶质细胞前体和少突胶质细胞的明显受损和丢失,成功建立了2d龄新生大鼠以少突胶质细胞前体为主、与人类早产儿脑室周围白质软化病理相似的脑室周围白质软化动物模型。  相似文献   
39.
目的:成纤维细胞生长因子2是一种多功能、作用广泛的细胞因子。就成纤维细胞生长因子2分子结构和生物学效应以及与骨髓间充质干细胞移植治疗大鼠急性心肌梗死的相关研究进行综述。资料来源:应用计算机检索PubMed数据库1990-01/2006-10有关成纤维细胞生长因子2的文章,检索词“FGF-2,molecular structure,biological effect,myocardial infarction and rat and marrows tem cell”,限定文章语言种类为English。同时计算机检索中国期刊全文数据库、万方数据库1990-01/2006-10期间的相关文章,检索词“碱性成纤维细胞生长因子”,限定文章语言种类为中文。资料选择:对资料进行初审,选取符合研究要求的有关文章找全文。纳入标准:①有关成纤维细胞生长因子2分子结构、生物学特性的研究。②有关骨髓间充质干细胞移植治疗急性心肌梗死的研究。资料提炼:共收集到34篇有关成纤维细胞生长因子2分子结构和生物学效应的文章,67篇有关骨髓间充质干细胞移植治疗大鼠急性心肌梗死的研究。选取其中31篇归纳总结。资料综合:①成纤维细胞生长因子2在人体内普遍存在,许多体外培养的细胞也自分泌成纤维细胞生长因子2。成纤维细胞生长因子2包括18000的低相对分子质量成纤维细胞生长因子2和高相对分子质量成纤维细胞生长因子2。成纤维细胞生长因子2翻译的起始密码子有两种:AUG和CUG。②成纤维细胞生长因子2有两种不同的受体,它们可与相应的受体结合发挥生物学功能。③在体外培养骨髓间充质干细胞的过程中,成纤维细胞生长因子2可促进其向心肌样细胞分化,在相对缺氧的环境下,提高心肌样细胞存活率。结论:成纤维细胞生长因子2作为一种多功能的细胞生长因子,在胚胎发育,创伤修复以及缺血、炎症、肿瘤等情况下,可作用于靶细胞上的特异性受体,发挥多种生理功能。它对新生血管形成过程中的毛细血管基底膜降解、内皮细胞迁移增殖、胶原合成及小血管腔形成等均有明显的促进作用。在相对缺氧的环境下,成纤维细胞生长因子2提高心肌样细胞存活率。  相似文献   
40.
Traumatic childhood events can have a significant impact on overall child functioning. Early identification and intervention could offer significant benefits for children’s mental health and educational trajectories, but how to effectively identify young children is a challenge. In this paper, we describe screening for exposure to traumatic events and associated symptoms of posttraumatic stress, and examine differences by child gender and grade level. A total of 402 elementary school children in grades 1–5 participated across four elementary schools. We describe modified administration procedures of screening instruments for these young children. Children who endorsed exposure to one or more traumatic events were individually assessed for posttraumatic stress symptom severity. Thirty-four percent (N = 138) of children screened experienced one or more traumatic events, and 75.4 % of those exposed to at least one traumatic event endorsed moderate levels or higher of posttraumatic stress symptoms. Internal consistency of the symptom self-report instrument was adequate for children of all grade levels. Posttraumatic stress symptom severity increased for children exposed to more types of events. No gender/grade differences were found in symptom severity. Findings suggest that young children are impacted by traumatic events in relatively high numbers, that they can reliably report their posttraumatic stress symptoms, and that a large portion of those exposed to trauma experience significant distress. These results highlight the importance of early screening and identification of these children to curtail potential risk for future academic, social, and psychological maladjustment.  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