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   1047篇
  免费   82篇
  国内免费   7篇
耳鼻咽喉   12篇
儿科学   41篇
妇产科学   10篇
基础医学   98篇
口腔科学   36篇
临床医学   120篇
内科学   317篇
皮肤病学   40篇
神经病学   77篇
特种医学   137篇
外科学   65篇
综合类   24篇
预防医学   66篇
眼科学   5篇
药学   38篇
  1篇
中国医学   1篇
肿瘤学   48篇
  2023年   5篇
  2022年   13篇
  2021年   20篇
  2020年   21篇
  2019年   19篇
  2018年   28篇
  2017年   18篇
  2016年   30篇
  2015年   27篇
  2014年   28篇
  2013年   45篇
  2012年   36篇
  2011年   57篇
  2010年   52篇
  2009年   49篇
  2008年   40篇
  2007年   53篇
  2006年   46篇
  2005年   53篇
  2004年   32篇
  2003年   22篇
  2002年   17篇
  2001年   10篇
  2000年   10篇
  1999年   14篇
  1998年   40篇
  1997年   47篇
  1996年   39篇
  1995年   20篇
  1994年   29篇
  1993年   22篇
  1992年   20篇
  1991年   10篇
  1990年   13篇
  1989年   26篇
  1988年   22篇
  1987年   9篇
  1986年   12篇
  1985年   10篇
  1984年   14篇
  1983年   14篇
  1982年   13篇
  1981年   11篇
  1980年   7篇
  1978年   3篇
  1977年   2篇
  1976年   4篇
  1972年   1篇
  1969年   1篇
  1967年   1篇
排序方式: 共有1136条查询结果,搜索用时 15 毫秒
11.
12.
Hardy  DC; Murphy  WA; Siegel  BA; Reid  IR; Whyte  MP 《Radiology》1989,171(2):403-414
The radiologic studies of 38 essentially untreated adults with X-linked hypophosphatemia (XLH) were reviewed to determine the prevalence of radiologic features, to compare the findings in men and in women, and to elucidate the natural history of the disease by comparing the findings in young, intermediate-age, and older patients. Bone-reinforcement lines were common, but no characteristic mineral mass alteration was established. Looser zones were more prevalent in older subjects. Osteoarthritis was common, occurring in the ankles, knees, feet, sacroiliac joints, and wrists. Enthesopathy was infrequent in the younger group but was present in every member of the intermediate and older groups and was often accompanied by extra ossicles. Curvatures of the lower-extremity long bones were common in all age groups. Three new skeletal alterations in XLH were found to be common: flaring of the iliac wings, trapezoidal distal femoral condyles, and alterations in talar morphology, including shortening of the talar neck and flattening of the talar dome. Technetium-99m methylene diphosphonate scintigrams of 17 subjects were often abnormal, depicting bowing deformity and focal tracer accumulation in diaphyseal cortices and in periarticular and extraarticular regions. The mean metabolic index was moderately elevated (4.0). Both radiographic and scintigraphic findings were more severe in men, consistent with hemizygosity. The natural history of untreated XLH in both sexes is characterized by the development of a variety of age-related skeletal abnormalities during adulthood.  相似文献   
13.
14.
Mitropoulos  KA; Martin  JC; Reeves  BE; Esnouf  MP 《Blood》1989,73(6):1525-1533
The endogenous, negatively charged surface that induces activation of the contact coagulation factors was investigated in plasmas taken from women in late pregnancy and control subjects of child-bearing age. The plasmas from the two groups of subjects were incubated at 4 degrees C for 24 hours either in plastic or in glass tubes and the factor VII coagulant activity (VIIc) was assayed in the treated plasmas. The activation of factor VII under these conditions involves the generation of enzymes derived from factor XII (XIIa). The contact surface is rate- limiting for the activation of factor VII in the plasmas in both groups of subjects and can be supplemented by large multilamellar liposomal vesicles carrying the appropriate density of negative charge. The size of these vesicles is within the range of sizes of the large lipoprotein particles (chylomicrons, very low and intermediate-density lipoproteins). The relationship between the density of negative charge on the liposomal vesicles and VIIc was similar in the late pregnancy and the control plasmas incubated in plastic tubes. At a saturating density of negative charge the observed relative VIIc was similar in both sets of plasmas. The incubation of late pregnancy or control plasma in plastic tubes in the presence of sodium stearate caused VIIc to increase with increasing concentration of the added fatty acid. These results suggest that large lipoprotein particles carrying the appropriate free fatty acid at a sufficient density of negative charge could provide the contact surface that induces the generation of factor XIIa and the subsequent activation of factor VII. Moreover, plasmas from women in late pregnancy have a higher concentration of potential surface and a higher density of negative charge than the plasmas from nonpregnant women.  相似文献   
15.
Lichtenstein  A; Berenson  J; Norman  D; Chang  MP; Carlile  A 《Blood》1989,74(4):1266-1273
Previous work with continuously cultured multiple myeloma lines suggested that cytokine production by tumor cells may mediate some of the medical complications of this disease. To further investigate this issue, we assayed freshly obtained bone marrow (BM) cells from myeloma patients for the in vitro production of cytokines and the presence of cytokine RNA. Production of cytokine protein was assessed by bioassays with the aid of specific neutralizing anticytokine antibodies. These assays detected interleukin-1 (IL-1) and tumor necrosis factor (TNF) secretion by myeloma BM cells, which was significantly greater than secretion from similarly processed BM cells of control individuals. In contrast, lymphotoxin and interleukin-2 (IL-2) production could not be detected. The levels of IL-1 and TNF produced in vitro peaked at 24 hours of culture and correlated with stage and the presence (or absence) of extensive osteolytic bone disease. Northern blot analysis demonstrated the presence of IL-1 beta and TNF RNA in uncultured myeloma BM cells but no detectable IL-1 alpha or lymphotoxin RNA. In addition, the amount of cytokine RNA correlated with protein production, being significantly greater in patients' BM cells than in control marrow. These data suggest a role for IL-1 beta and/or TNF in the pathophysiology of multiple myeloma and argue against a role for lymphotoxin or IL-2.  相似文献   
16.
A non-human primate antiserum was prepared to acute lymphoblastic leukemia of T-cell phenotype (T-ALL) and, after absorptions with normal blood elements, reacted by immunofluorescence and microcytotoxicity to all the T-ALL tested. In addition, the antiserum reacted with cells from about 70% of the common ALL studied and immunoprecipitated the common ALL antigen of 100,000 daltons. However, when the anti-T-ALL serum was absorbed with with lymphoblasts from common ALL, it failed to react with common ALL lymphoblasts, yet reacted significantly with cells from patients with T-ALL phenotype and defined a 100,000-dalton membrane component not found on common ALL lymphoblasts. In addition, sequential immunoprecipitation of 125I-labeled T-ALL membranes by anti- common-ALL serum followed by anti-T-ALL serum detected the T-ALL membrane component of 100,000 daltons that was not found on common ALL. Thus, our results demonstrate the presence of of a unique human T-ALL antigen present on all T-ALL distinct from the common ALL antigen.  相似文献   
17.
作为标准化的非手术治疗,诱导化疗(ICT)在治疗局部晚期头颈鳞癌已有几十年的历史,但是关于其作用尚存争议。同期放化疗(CRT)是目前标准化的非手术治疗,然而由于ICT能够使肿瘤体积缩小,提高放疗的可行性,改善患者对放疗的耐受力,增加放疗后器官功能保留的可能性及降低远处转移率。所以,对ICT的研究从未停止。该文对近期随机试验进行回顾分析,与手术或单独CRT比较,评估ICT中紫杉醇的价值。Meta分析比较ICT中紫杉醇和顺铂及5氟尿嘧啶的作用。之前的随机试验中,并没有ICT提高生存率的报道。但  相似文献   
18.
19.
Modern population based oral health management requires a complete understanding of the impact of disease in order to provide efficient and effective oral health care and guidance. Periodontitis is an important cause of tooth loss and has been shown to be associated with a number of systemic conditions. The impact of oral conditions and disorders on quality of life has been extensively studied. However, the impact of periodontitis on quality of life has received less attention. This review summarizes the literature on the impact of periodontitis on oral health‐related quality of life (OHRQoL). Relevant publications were identified after searching the MEDLINE and EMBASE electronic databases. Screening of titles and abstracts and data extraction was conducted. Only observational studies were included in this review. Most of the reviewed studies reported a negative impact of periodontitis on OHRQoL. However, the reporting standards varied across studies. Moreover, most of the studies were conducted in developed countries.  相似文献   
20.
The aim of this study was to compare three groups of Brazilian psychoactive substance (PAS) abuse patients (crack cocaine users, cocaine snorters, and non-cocaine PAS users) in terms of psychiatric comorbidities and severity of psychosocial problems. A cross-sectional, multi-center study was conducted at five Brazilian research centers. A total of 738 current PAS abusers seeking specialized treatment (outpatient and inpatient clinics) were assessed using the sixth version of the Addiction Severity Index (ASI-6): 293 patients using crack cocaine were compared with 126 using powder cocaine and 319 using non-cocaine PAS (mostly alcohol and marijuana). Psychiatric comorbidities were assessed in a smaller sample (290 cases), originating from three of the centers, using the Mini International Neuropsychiatric Interview Plus (MINI-Plus). Crack and powder cocaine users were significantly younger than non-cocaine PAS users (31.1 ± 8.1 and 32.9 ± 8.8 vs. 42.4 ± 12, respectively; p < .001). Crack users presented a higher rate of antisocial personality disorder (25%) than powder cocaine (9%) and non-cocaine PAS users (9%), even when adjusted for confounding factors (Pr = 2.6; 95% CI 1.10-6.40). According to ASI-6 summary scores, crack users presented a significantly higher rate of occupational, family, and legal problems and reported more illegal and violent activities such as burglary and theft (23%) and threatening or assaulting (32%) than non-cocaine PAS users. Our findings, combined with the recent increase observed in the prevalence of crack use in Brazil, highlight the severity of psychiatric symptoms and psychosocial problems related to this powerful drug and corroborate the already suggested association between crack/cocaine, violence, and legal problems. Treatment programs for crack users should routinely consider the possibility of associated psychiatric comorbidities, such as antisocial personality disorder, which may affect treatment outcomes.  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