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   1714篇
  免费   49篇
  国内免费   23篇
耳鼻咽喉   20篇
儿科学   51篇
妇产科学   8篇
基础医学   130篇
口腔科学   15篇
临床医学   115篇
内科学   176篇
皮肤病学   39篇
神经病学   569篇
特种医学   57篇
外科学   124篇
综合类   187篇
预防医学   45篇
眼科学   20篇
药学   182篇
中国医学   17篇
肿瘤学   31篇
  2023年   14篇
  2022年   44篇
  2021年   84篇
  2020年   50篇
  2019年   44篇
  2018年   57篇
  2017年   59篇
  2016年   58篇
  2015年   40篇
  2014年   102篇
  2013年   113篇
  2012年   114篇
  2011年   86篇
  2010年   77篇
  2009年   72篇
  2008年   82篇
  2007年   54篇
  2006年   57篇
  2005年   63篇
  2004年   50篇
  2003年   20篇
  2002年   24篇
  2001年   29篇
  2000年   43篇
  1999年   30篇
  1998年   19篇
  1997年   24篇
  1996年   19篇
  1995年   24篇
  1994年   29篇
  1993年   14篇
  1992年   15篇
  1991年   11篇
  1990年   12篇
  1989年   12篇
  1988年   13篇
  1987年   12篇
  1986年   12篇
  1985年   19篇
  1984年   6篇
  1982年   10篇
  1981年   7篇
  1980年   6篇
  1979年   4篇
  1978年   10篇
  1977年   8篇
  1976年   6篇
  1974年   5篇
  1973年   4篇
  1971年   4篇
排序方式: 共有1786条查询结果,搜索用时 15 毫秒
21.
Cocaine, diethylpropion, chlorphentermine, and fenfluramine were compared on a drug-maintained progressive-ratio procedure in baboons. Intravenous infusions of drug were contingent on completion of a fixed-ratio response requirement (fixed number of lever-press responses) with a 3-h time-out period following each infusion. Prior to testing each dose of drug, stable self-infusion performance was first established with 0.4 mg/kg cocaine when the fixed-ratio requirement was 160. Subsequently, a test dose of drug was substituted for the standard dose of cocaine. If the dose of drug maintained a criterion level of self-infusion performance (six or more infusions per day for 2 days), the ratio requirement was systematically increased every day until the breaking point at which the self-infusion performance fell below a criterion level (one or zero infusionsper day). Fenfluramine did not maintain criterion self-infusion performance at any dose tested (0.02–5.0 mg/kg). The dose ranges of the other drugs that maintained maximum breaking points were 1.0–5.6 mg/kg for chlorphentermine, 1.0–3.0 mg/kg for diethylpropion, and 0.1–0.4 mg/kg for cocaine. Within-animal comparison of the maximum breaking points indicated that cocaine maintained the highest breaking points, followed in order by diethylpropion, chlorphentermine, and fenfluramine. The rank ordering of these drugs with the breaking point measure corresponds well with both the results of other animal experiments on measurement of reinforcing efficacy of these drugs and with the clinical information about the human subjective effects and abuse of these drugs.  相似文献   
22.
Summary A young woman presented a mixed congenital and familial immunodeficiency syndrome consisting in an absence of IgA and lowered levels of IgG and IgM, with a defect in cellular immunity. She had a mild malabsorption syndrome with slight alterations of the jejunal mucosa. Non-caseating tuberculoid granulomata were found in skin lesions, in lymph nodes and in the spleen. At age 27 the patient died of a neurological disease of 4 months duration. Autopsy revealed a very widespread demyelinating process involving mainly the right cerebellar hemisphere but also most of the pons and left cerebellum, with the typical morphologic characters of PML. In the hemispheres lesions were limited to microscopical microglial nodules with discrete demyelination. A review of 86 published cases of PML revealed 9 other cases in which lesions showed a strong predilection for the subtentorial territories. This sampling allows for the assumption that some 11% of the cases of PML have this particular lesion distribution. Other pertinent features of this case are briefly discussed.
  相似文献   
23.
To determine whether there are characteristic changes in event-related potentials (ERPs) in parkinsonian syndromes we studied 8 patients with progressive supranuclear palsy (PSP), 10 patients with corticobasal degeneration (CBD), 9 patients with striatonigral degeneration (SND), and 16 patients with idiopathic Parkinson's disease (PD) with a mean duration of illness shorter than 5 years in each group. A visual oddball paradigm was employed to elicit P300. P300 to the rare target and rare nontarget stimuli and reaction time (RT) to rare target stimuli in each group were compared with those in the corresponding age-matched normal control group and to each other after age correction. The correlation of P300 and RT to motor disability score was also studied. In PSP P300 amplitude was markedly reduced while in CBD P300 latency was prolonged. P300 amplitude to rare nontargets in SND and PD was attenuated. The mean RT in the PSP and the CBD group was significantly longer than in the other two groups. The mean RT in PD and P300 amplitude to rare nontargets in both CBD and PD showed significant correlation with the severity of motor disability. Simultaneous measurement of P300 and RT may yield useful supplementary information in facilitating diagnosis of parkinsonian syndromes in addition to clinical criteria. Received: 6 April 1999, Received in revised form: 5 August 1999, Accepted: 12 January 2000  相似文献   
24.
Introduction: Chronic progressiveexternal ophthalmoplegia is characterisedby limitation of ocular motility in alldirections of gaze and ptosis.Innervational or myogenic factors wereclaimed to be responsible for thismotility disorder. The aim of thisstudy was toinvestigate the extraocular muscles inCPEO with computerized tomography in an attemptto distinguish extraocular musclemorphology caused by this disorderfrom that occurring in normal individuals.Methods: Eighteen orbits from 9patients diagnosed with CPEOwere included in the study. Axialand coronal scans were obtained for CTevaluation of extraocular muscles and thedimensions of extraocular muscles were measured.The control group consisted of40 orbits belonging to 20 individuals and,the results were compared with a student'st test.Results: The thickness (the verticaldimension of vertical recti and thehorizontal dimension of horizontal recti)of all rectus muscles wassignificantly decreased in comparison with the controlgroup, whereas the width (the horizontal dimensionof vertical recti and the verticaldimension of horizontal recti) was similar inboth the diseased and normal orbits.In all the rectus musclesof the diseased orbits,the normal fusiform shape was lost and the muscles appeared asthin bands.Discussion: The differentiation ofCPEO from other myogenic and neurogenicdisorders may present difficulty,and a cluster of criteria are required fora final diagnosis. CT has provento be a valuable tool in assessing extraocularmuscles [1, 2]. In this study, an extremeatrophy of all rectus muscles wasdemonstrated by means of CT. This diagnostic method mayconsequently contribute to a properdiagnosis of CPEO.  相似文献   
25.
目的 探讨非典型帕金森病(APD)相关疾病的临床诊断思路.方法 通过回顾性分析笔者医院2006~2011年收治的48例APD相关疾病患者的临床资料包括病史、体格检查、临床表现、实验室检查、影像学检查、认知功能评估、左旋多巴(L-dopa)试验结果,复习文献,总结分析临床资料特征,并依据APD相关疾病的诊断标准作出临床诊断.结果 48例患者中,肌张力增高42例、震颤40例、运动迟缓39例、姿势反射异常32例、步态异常29例、直立性低血压13例、腱反射亢进11例、认知功能障碍11例、垂直性凝视麻痹和球麻痹各10例、共济失调和病理征阳性各8例、角膜K-F环7例、视幻觉5例、一侧肢体忽略并失用3例;肝功能异常9例、血小板减少8例、血清铜蓝蛋白降低7例、凝血功能异常5例;头颅CT:基底核区低密度影19例,脑室扩大17例,脑萎缩14例;头颅MRI:基底节区异常信号30例,脑室扩大20例,弥漫性脑萎缩18例,脑干和小脑萎缩15例,海马萎缩7例,双侧苍白球T2高信号4例.壳核“裂隙征”8例,脑桥“十字征”7例,中脑“蜂鸟征”6例;L-dopa试验反应不良46例;蒙特利尔认知评估量表(MoCA)总分<26分23例.出院诊断:多系统萎缩(MSA)18例、进行性核上性麻痹(PSP)10例、Wilson病(WD)7例、路易体痴呆(DLB)6例、伴帕金森综合征(PS)的阿尔茨海默病(AD)5例和皮质基底核变性(CBD)2例.结论 APD相关疾病间,虽然临床表现有许多相似之处,但临床特征、诊断标准及治疗转归各不相同,正确区分十分必要.  相似文献   
26.
低分子肝素与小剂量尿激酶治疗进展性脑卒中疗效比较   总被引:1,自引:0,他引:1  
目的:探讨小剂量尿激酶和低分子肝素对急性进展性缺血性脑卒中的治疗作用。方法:将60例急性进展性脑卒中患者随机分成低分子肝素组30例,予低分子肝素0.4ml,2次/d,皮下注射;尿激酶组30例,予尿激酶20~30万单位加生理盐水100ml静滴,连用7d;于治疗前、治疗7d比较两组神经功能缺损评分。结果:低分子肝素组治疗总有效率90.0%,尿激酶组83.3%,二者比较差异无统计学意义(P〉0.05),但尿激酶组出血副作用较大。结论:低分子肝素治疗急性进展性脑卒中较小剂量尿激酶的疗效可靠,相对安全。  相似文献   
27.
适当选取切边算子,引入函数的带边界的模,对文题建立先验估计,证明了高阶可微分解的存在性定理。  相似文献   
28.
Rare adipose disorders (RADs) including multiple symmetric lipomatosis (MSL), lipedema and Dercum''s disease (DD) may be misdiagnosed as obesity. Lifestyle changes, such as reduced caloric intake and increased physical activity are standard care for obesity. Although lifestyle changes and bariatric surgery work effectively for the obesity component of RADs, these treatments do not routinely reduce the abnormal subcutaneous adipose tissue (SAT) of RADs. RAD SAT likely results from the growth of a brown stem cell population with secondary lymphatic dysfunction in MSL, or by primary vascular and lymphatic dysfunction in lipedema and DD. People with RADs do not lose SAT from caloric limitation and increased energy expenditure alone. In order to improve recognition of RADs apart from obesity, the diagnostic criteria, histology and pathophysiology of RADs are presented and contrasted to familial partial lipodystrophies, acquired partial lipodystrophies and obesity with which they may be confused. Treatment recommendations focus on evidence-based data and include lymphatic decongestive therapy, medications and supplements that support loss of RAD SAT. Associated RAD conditions including depression, anxiety and pain will improve as healthcare providers learn to identify and adopt alternative treatment regimens for the abnormal SAT component of RADs. Effective dietary and exercise regimens are needed in RAD populations to improve quality of life and construct advanced treatment regimens for future generations.  相似文献   
29.
We developed an index to measure progressive realization for the human right to water and sanitation. While in this study we demonstrate its application to the non-discrimination and equality component for water, the conceptual approach of the index can be used for all the different components of the human right. The index was composed of one structural, one process, and two outcome indicators and is bound between −1 and 1, where negative values indicate regression and positive values indicate progressive realization. For individual structural and process indicators, only discrete values such as −1, −0.5, 0, 0.5, and 1 were allowed. For the outcome indicators, any value between −1 and 1 was possible, and a State's progress was evaluated using rates of change. To create an index that would allow for fair comparisons between States and across time, these rates of change were compared to benchmarked rates, which reflect the maximum rates a State can achieve. Using this approach, we calculated the index score for 56 States in 2010 for which adequate data were available and demonstrated that these index scores were not dependent on factors such as achieved level of coverage or gross national income. The proposed index differs from existing measures of inequality as it measures rate of change and not level of achievement, and thus addresses the principle of progressive realization that is fundamental to human rights.  相似文献   
30.
目的:探讨进展性缺血性脑卒中的发生是否与患者的血脂、血糖、同型半胱氨酸、纤维蛋白原及C反应蛋白等水平有关。方法整群收集了2009年9月—2012年9月该院收治的239例进展性缺血性脑卒中患者组成治疗组,并选择同期非进展性缺血性脑卒中239例对照患者的临床资料为对照组,对研究对象的血糖、血脂、纤维蛋白原、同型半胱氨酸水平等结果进行系统的研究,并与非进展性缺血性脑卒中相对比。结果进展组与非进展组两组患者血糖、血脂、CRP、FIB、HCY等比较,P均>0.05,差异无统计学意义。结论进展性缺血性脑卒中的发生与患者的血糖、血脂、纤维蛋白原、同型半胱氨酸水平等无相关性。  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