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   22987篇
  免费   1502篇
  国内免费   41篇
耳鼻咽喉   153篇
儿科学   711篇
妇产科学   745篇
基础医学   2889篇
口腔科学   320篇
临床医学   3670篇
内科学   3905篇
皮肤病学   261篇
神经病学   2372篇
特种医学   442篇
外科学   2070篇
综合类   280篇
一般理论   32篇
预防医学   3420篇
眼科学   342篇
药学   1340篇
中国医学   23篇
肿瘤学   1555篇
  2023年   142篇
  2022年   195篇
  2021年   425篇
  2020年   299篇
  2019年   457篇
  2018年   567篇
  2017年   420篇
  2016年   471篇
  2015年   561篇
  2014年   769篇
  2013年   1149篇
  2012年   1682篇
  2011年   1828篇
  2010年   956篇
  2009年   859篇
  2008年   1569篇
  2007年   1710篇
  2006年   1602篇
  2005年   1560篇
  2004年   1579篇
  2003年   1429篇
  2002年   1420篇
  2001年   241篇
  2000年   163篇
  1999年   192篇
  1998年   270篇
  1997年   232篇
  1996年   168篇
  1995年   188篇
  1994年   173篇
  1993年   122篇
  1992年   119篇
  1991年   85篇
  1990年   71篇
  1989年   75篇
  1988年   75篇
  1987年   66篇
  1986年   45篇
  1985年   72篇
  1984年   66篇
  1983年   54篇
  1982年   65篇
  1981年   59篇
  1980年   34篇
  1979年   39篇
  1978年   22篇
  1977年   20篇
  1975年   13篇
  1974年   13篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The anti-granulocyte activity of serum from patients with B-cell chronic lymphocytic leukaemia (CLL) and other lymphoproliferative disorders was investigated. Granulocyte-binding IgG was measured in 34 patients with CLL, 13 patients with hairy cell leukaemia, one patient with prolymphocytic leukaemia, two patients with Sézary cell leukaemia, and seven patients with chronic T-cell lymphocytosis who had a predominance of circulating large granular lymphocytes. Anti-granulocyte activity was absent in CLL and its variants, but present in the majority of granulocytopenic patients with chronic T-cell lymphocytosis. In one of these patients, granulocytopenia was associated with complement-activating IgG granulocyte antibody. Thus, antibody-mediated granulocyte injury appears to be an unusual occurrence in chronic lymphocytic leukaemia, but is a frequent complication of chronic T-cell lymphocytosis.  相似文献   
22.
23.
Arsenic pollution has become increasingly severe. It occurs as the result of geological processes and different human activities. Arsenic toxicity at the respiratory level occurs mainly by inhalation of products of coal combustion. The aim of this study was to evaluate sodium arsenite (As3+) toxicity in murine alveolar macrophages (AMs) in vitro and its association with the alterations in cell metabolism.

No changes in viability, apoptosis or cell area were detected in AMs treated with As3+ concentrations up to 2 μM for 24–96 h. A marked decrease in these end-points was observed for As3+ concentrations ranging from 2.5 μM to 10 μM.

Regarding the dynamics of the endo-exocytic process triggered by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell incorporation, no variations were detected for As3+ concentrations lower than 2 μM while higher concentrations markedly modified this response.

MTT specific activity, as a measure of cell metabolic activity, was not modified irrespective of the As3+ concentration assayed. However, nitroblue tetrazolium (NBT) specific activity, as a measure of superoxide anion generation, is responsive but only to low As3+ doses.

Although this study focuses on lung macrophages, the effects of As3+ described herein may also apply to the response of macrophages residing in other organs.

Arsenite modifies the metabolic and the oxidative status of AMs in vitro. When macrophages are in an As3+ rich medium, they exhibit a reduction in respiratory burst levels and lose their intrinsic capacity to respond to toxicants.  相似文献   

24.
Castleman disease is a rare disorder characterized by lymphoid hyperplasia which rarely manifests in children. We present 2 cases which highlight both histologic variants of this disease, and provide suggestions regarding workup and treatment with the goal of making practitioners aware of Castleman disease in the differential diagnosis of a child presenting with vague symptoms.  相似文献   
25.
26.
27.
28.
The authors tested the hypothesis that short stature predicts adult-onset asthma independent of obesity among women in the Nurses' Health Study. Height, weight, and physician-diagnosed asthma were assessed with validated questionnaire items. Proportional hazard models adjusted separately for weight and body mass index. The rate of newly diagnosed asthma was 1.55 times greater in the shortest versus the tallest quintile after adjustment for weight (95% CI, 1.26-1.91). After adjustment for body mass index, the rate ratio was 1.16 (95% CI, 0.94-1.42). Short stature predicted adult-onset asthma in a large cohort of women, but this association was not independent of obesity.  相似文献   
29.
Pregnant and parenting adolescents living in inner cities are at risk for acquiring HIV through unprotected sexual activity. In addition to individual risk behaviors, a lack of socioeconomic and other environmental resources create risk environments that make certain communities vulnerable to both adolescent pregnancy and HIV/AIDS. Research indicates that adolescent parents, many who have histories of childhood trauma, may use their experience of young parenthood and the concomitant feelings of parental protectiveness as a source of renewed hope for their future. The purpose of this report is to explore the relationship between history of childhood abuse and high risk behaviors in adolescent Latino mothers and fathers enrolled in a randomized clinical trial of a culturally rooted, couple-focused HIV prevention program. In addition, this report describes the HIV prevention program that was designed specifically for young Latino parents wherein maternal and paternal protectiveness are viewed as intrinsic and developing critical factors that promote resiliency and motivate behavioral change.  相似文献   
30.
PURPOSE: To compare visual acuity results obtained using the Lea Symbols chart with visual acuity results obtained with the Bailey-Lovie chart in school-aged children and adults using a within-subjects comparison of monocular acuity results. METHODS: Subjects were 62 individuals between 4.5 and 60 years of age, recruited from patients seen in five optometry clinics. Each subject had acuity of the right eye and the left eye tested with the Lea Symbols chart and the Bailey-Lovie chart, with order of testing varied across subjects. Outcome measures were monocular logarithm of the minimum angle of resolution (logMAR) visual acuity and inter-eye acuity difference in logMAR units for each test. RESULTS: Correlation between acuity results obtained with the two charts was high. There was no difference in absolute inter-eye acuity difference measured with the two acuity charts. However, on average, Lea Symbols acuity scores were one logMAR line better than Bailey-Lovie acuity scores, and this difference increased with worse visual acuity. CONCLUSIONS: The Lea Symbols chart provides a measure of inter-eye difference that is similar to that obtained with the Bailey-Lovie chart. However, the monocular acuity results obtained with the Lea Symbols chart differ from those obtained with the Bailey-Lovie chart, and the difference is dependent on the individual's absolute level of visual acuity.  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