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   5415篇
  免费   557篇
  国内免费   277篇
耳鼻咽喉   51篇
儿科学   163篇
妇产科学   19篇
基础医学   569篇
口腔科学   127篇
临床医学   473篇
内科学   775篇
皮肤病学   59篇
神经病学   240篇
特种医学   288篇
外科学   450篇
综合类   984篇
一般理论   9篇
预防医学   476篇
眼科学   76篇
药学   616篇
  8篇
中国医学   494篇
肿瘤学   372篇
  2024年   22篇
  2023年   67篇
  2022年   151篇
  2021年   197篇
  2020年   139篇
  2019年   113篇
  2018年   118篇
  2017年   136篇
  2016年   102篇
  2015年   185篇
  2014年   217篇
  2013年   271篇
  2012年   396篇
  2011年   364篇
  2010年   350篇
  2009年   299篇
  2008年   352篇
  2007年   312篇
  2006年   302篇
  2005年   250篇
  2004年   194篇
  2003年   148篇
  2002年   153篇
  2001年   153篇
  2000年   128篇
  1999年   72篇
  1998年   35篇
  1997年   26篇
  1996年   29篇
  1995年   22篇
  1994年   26篇
  1992年   51篇
  1991年   57篇
  1990年   53篇
  1989年   57篇
  1988年   63篇
  1987年   56篇
  1986年   66篇
  1985年   46篇
  1984年   46篇
  1983年   38篇
  1982年   27篇
  1979年   40篇
  1978年   23篇
  1977年   24篇
  1976年   23篇
  1975年   24篇
  1974年   28篇
  1973年   25篇
  1971年   24篇
排序方式: 共有6249条查询结果,搜索用时 15 毫秒
11.
Forty suicide-attempt patients who were consecutively admitted to an intensive-care unit, their significant others and treatment personnel were investigated by semistructured interviews. The patients were divided into neurosis (n = 14), abuse (n = 19) and psychosis (n = 7) groups. Twenty-one of the patients (52%) had lost contact with one or both parents before the age of 18, in 25% of cases owing to death and in 27% because of the parents' divorce or separation. Parents and/or siblings of 19 patients (47%) had shown suicidal behaviour in the form of attempted suicide and/or suicide. Differences between the groups were not significant. Alcohol abuse in the parental home was overrepresented in the abuse group compared with the other groups. The role of identification with the dead and suicidal parent in prompting suicidal actions in adulthood is discussed, as well as that of the impeded evolution of stable external object relations owing to parental losses.  相似文献   
12.
A total of 88 interviews were conducted with 40 people attempting suicide who were receiving care in an intensive-care unit, and 129 interviews were carried out with their relatives and friends. The subjects were divided into 3 diagnostic groups: neurosis (n = 14), abuse (n = 19) and psychosis (n = 7). The incidence of relatives' failure to provide care after the suicide attempt--turning-away reactions as well as do not resuscitate orders, a form of passive euthanasia--was investigated. In 8 cases, partners of patients in the abuse and neurosis groups showed turning-away reactions. In 2 cases, relatives of elderly patients in the neurosis group said to the doctor that life-preserving measures should not be taken. Relatives explained their behaviour by saying that they had the best interests of the suicidal individual at heart. In-depth interviews, however, revealed that these reactions were a manifestation of the relatives own psychic conflicts, brought forth by the confrontation with the depressed and suicidal patient. Turning-away reactions and do not resuscitate orders might be interpreted as expressing the relatives' aggressiveness towards the suicidal individual and attempts to escape from a difficult situation. It is important that doctors stand up for the interests of suicidal people, which at times may conflict with relatives' interests, and help the relatives to sort out their problems and wishes with respect to the problem areas of passive euthanasia.  相似文献   
13.
For a prospective study of lead exposure and early development, we recruited pregnant women from a lead smelter town and from an unexposed town in Yugoslavia and followed their children through 7 years of age. In this paper we consider associations between lifetime lead exposure, estimated by the area under the blood lead (BPb) versus time curve (AUC7), and intelligence, with particular concern for identifying lead's behavioral signature. The Wechsler Intelligence Scales for Children-Version III (WISC-III) was administered to 309 7-year-old children, 261 of whom had complete data on intelligence, blood lead, and relevant sociodemographic covariates (i.e., Home Observation for the Measurement of the Environment (HOME), birth weight, gender, sibship size, and maternal age, ethnicity, intelligence, and education). These showed anticipated associations with 7-year intelligence, explaining 41-4% of the variance in Full Scale, Performance, and Verbal IQ. Before covariate adjustment, AUC7 was unrelated to intelligence; after adjustment, AUC7 explained a significant 2.8%-4.2% of the variance in IQ. After adjustment, a change in lifetime BPb from 10 to 30 micro/dl related to an estimated decrease of 4.3 Full Scale IQ points; estimated decreases for Verbal and Performance IQ were 3.4 and 4.5 points, respectively. AUC7 was significantly and negatively related to three WISC-III factor scores: Freedom from Distractibility, Perceptual Organization, and Verbal Comprehension; the association with Perceptual Organization was the strongest. Consistent with previous studies, the IQ/lead association is small relative to more powerful social factors. Findings offer support for lead's behavioral signature; perceptual-motor skills are significantly more sensitive to lead exposure than are the language-related aspects of intelligence.  相似文献   
14.
①目的 探讨库欣综合征病人低钾血症的发生与氢化可的松的关系。②方法 采用放免法测定 6 4例库欣综合征病人 2 4h尿游离氢化可的松 (UFC) ,血清氢化可的松 (SC)及血浆促皮质素 (ACTH)水平 ,比较增生型与腺瘤型病人中低钾血症组与非低钾血症组之间UFC ,SC和ACTH等指标的差异。③结果 库欣综合征中增生型及腺瘤型病人低钾血症的发生率均较高 ,分别为 30 .4 3%及 33.33% .增生型中低钾血症者UFC ,SC(2 4 :0 0 ,8:0 0 ) ,血浆ACTH(8:0 0 )含量显著高于无低钾血症者 ,差异有显著性 (t=2 .10~ 3.0 2 ,P <0 .0 5 ) ;腺瘤型中有低钾血症者仅UFC含量显著高于无低钾血症者 (t=3.2 7,P <0 .0 5 )。直线相关分析表明 ,低钾血症的发生与UFC含量呈正相关 (r=0 .32 5 ,P <0 .0 5 )。④结论 库欣综合征病人低钾血症的发生与体内氢化可的松水平有关 ,UFC水平可作为预测低钾血症是否发生的一个重要指标  相似文献   
15.
目的:从脑内铁代谢的角度研究铁在外伤后癫(PTE)发病机制中的可能作用。方法:用ELISA方法检测PTE大鼠模型脑组织内铁蛋白(Ft)和转铁蛋白(Tf)的动态含量。结果:早期Ft在整个脑组织内呈现为即刻反应性升高,15d后其含量在实验对侧脑组织内恢复至正常范围,而在实验侧脑组织内呈现继续升高的趋势;Tf含量只在实验侧脑组织内升高,且呈现随时间继续升高趋势。结论:PTE大鼠模型中的铁代谢过程十分复杂,相关蛋白尤其是Tf含量的增加提示铁可能是外伤后癫灶形成机制的一部分。  相似文献   
16.
We describe a patient with bilateral ureteral pseudodiverticulosis of 10 years’ duration before developing transitional carcinoma of the pelvis.  相似文献   
17.
Previous studies have suggested that, for the same power output, arm exercise requires higher oxygen uptake (VO2), carbon dioxide output (VCO2), and ventilation (VE) than leg exercise and that response kinetics are slower. To evaluate these differences, four healthy subjects performed a total of 95 arm cranking tests. Each subject performed several tests at each of three or four power outputs spaced evenly below the maximum the subject could sustain (average = 53 W). Breath-by-breath responses to identical stimuli were averaged. End-exercise blood lactate was determined at each power output. Responses were compared to leg exercise responses in these subjects (J. Appl. Physiol. 67:547-555, 1989). For power outputs unassociated with lactic acidosis, differences between steady-state VO2, VCO2, and VE responses for arm and leg exercise were not significant. At higher power outputs, the higher VO2, VCO2, and VE during arm exercise were well correlated with higher lactate. For power outputs not engendering lactic acidosis, the time constants (tau) for VO2, VCO2 and VE were not greatly different for arm than for leg exercise. For each variable, at higher power outputs tau became longer by an amount correlated with higher lactate level. Like leg exercise, the slower kinetics of VO2 and VE (but not VCO2) at higher power outputs were well described as a superimposed slower component. We conclude that both dynamic and steady-state responses of VE and gas exchange to arm exercise do not differ substantially from those to leg exercise so long as the power output does not elevate blood lactate.  相似文献   
18.
生长抑素受体亚型在人鼻咽癌细胞株CNE2中表达   总被引:3,自引:0,他引:3  
背景与目的:生长抑素受体(somatostatin receptor SSTR)在许多肿瘤组织均有表达,为生长抑素类似物如奥曲肽用于这些肿瘤的治疗提供了生物学基础,但对生长抑素受体在鼻咽癌中表达情况的研究甚少。本研究旨在了解生长抑素受体基因在鼻咽癌细胞中的表达情况,为生长抑素类似物用于鼻咽癌治疗的进一步研究提供试验基础。方法:采用RT—PCR法和SP免疫组化法联合检测体外培养的人鼻咽癌细胞株CNE2的SSTRs表达,并对PCR mRNA产物测序以鉴定结果。结果:RT—PCR提示人鼻咽癌细胞株CNE2分别表达生长抑素受体亚型SSTR1、SSTR2、SSTR4;免疫组化结果:人鼻咽癌细胞株CNE2表达SSTR1、SSTR2A为强阳性(〉60%),表达SSTR4为弱阳性、SSTR2介于两者之间、SSTR3和SSTR5则无表达。结论:我们的研究证实人鼻咽癌细胞株CNE2有多种生长抑素受体亚型基因表达,且以表达SSTR1、SSTR2较多。  相似文献   
19.
A significant decline (34.5%) in the suicide rate occurred in 1984–1988 throughout the USSR. The decline was observed shortly after the introduction of strict restrictions on the sale of alcohol. We tested the hypothesis that the restrictive alcohol policy in the first years of perestroika (June 1985) caused the fall in suicide rates in the former USSR. Data on alcohol consumption, violent death caused by external injury and poisoning (n= 916,315), death due to accidental alcohol poisoning (n= 77,837), suicide (n= 192,305) and death undetermined whether accidentally or purposely (n= 54,253) were analyzed for all former Soviet republics for 1984, 1986, 1988 and 1990. Men were chosen for the analysis, since men are more prone to abuse alcohol than women. Regression analysis with alcohol consumption as the independent variable and suicide rates and violent death rates as dependent variables shows that suicide and alcohol consumption were positively correlated as were violent death and alcohol consumption. In the republics with high alcohol consumption (Slavic and Baltic), suicide rates were also high. In the Caucasian republics, low alcohol consumption was associated with low suicide rates. For most republics, alcohol seems to explain more than 50% of suicides. Alcohol also has considerable explanatory value for violent death. Thus, a restrictive alcohol policy might be a way to reduce suicide and violent death.  相似文献   
20.
目的总结重型肝炎实施急诊肝移植的经验,探讨其手术指征。方法回顾性分析34例拟行急诊肝移植治疗的重型肝炎并急性肝衰竭患者的临床资料,其中11例实施急诊肝移植手术。结果34例患者中,14例在等待供体中死亡,另9例在转入我科时已丧失手术机会,于3d内死亡。11例急诊肝移植均采用改良背驮式肝移植,其中1例术后7d死于肺部感染、急性呼吸窘迫综合征(ARDS),1例术后20d死于原发性移植肝功能不良合并肾功能衰竭,其他9例术后均恢复顺利。随访6~29个月,1例于术后12个月死于慢性排斥反应,余8例情况良好。结论急诊肝移植是治疗重型肝炎合并急性肝功能衰竭移植的有效方法,其指征为:(1)Ⅱ级及Ⅱ级以上的进行性脑病;(2)PT延长15 s以上(或凝血酶原活动度<30%);(3)血清TBIL(300μmol/L(17.5mg/dl)或TBIL进行性升高(每天>17.1μmol/L)。  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