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   4274篇
  免费   297篇
  国内免费   21篇
耳鼻咽喉   27篇
儿科学   173篇
妇产科学   94篇
基础医学   640篇
口腔科学   83篇
临床医学   440篇
内科学   952篇
皮肤病学   85篇
神经病学   352篇
特种医学   189篇
外科学   424篇
综合类   137篇
一般理论   3篇
预防医学   319篇
眼科学   55篇
药学   279篇
中国医学   8篇
肿瘤学   332篇
  2023年   40篇
  2022年   61篇
  2021年   154篇
  2020年   82篇
  2019年   104篇
  2018年   100篇
  2017年   72篇
  2016年   113篇
  2015年   117篇
  2014年   131篇
  2013年   190篇
  2012年   259篇
  2011年   265篇
  2010年   163篇
  2009年   129篇
  2008年   228篇
  2007年   236篇
  2006年   232篇
  2005年   211篇
  2004年   187篇
  2003年   167篇
  2002年   172篇
  2001年   82篇
  2000年   63篇
  1999年   74篇
  1998年   75篇
  1997年   54篇
  1996年   45篇
  1995年   32篇
  1994年   55篇
  1993年   18篇
  1992年   45篇
  1991年   35篇
  1990年   42篇
  1989年   40篇
  1988年   50篇
  1987年   36篇
  1986年   39篇
  1985年   33篇
  1984年   31篇
  1983年   29篇
  1982年   21篇
  1981年   18篇
  1980年   16篇
  1979年   21篇
  1978年   16篇
  1977年   15篇
  1976年   14篇
  1972年   12篇
  1966年   10篇
排序方式: 共有4592条查询结果,搜索用时 15 毫秒
61.
Disease Overview: Lymphomas, both Hodgkin’s and non-Hodgkin’s lymphomas, are one of the most common cancers in the head and neck area. The extra-nodal variant of lymphoma is rare, but it is the most common non-Hodgkin’s lymphoma (ENHL). Furthermore, it is difficult to diagnose due to its non-specific clinical and radiological features, which can mimic other benign or malignant clinical manifestations. The study: This retrospective study involved 72 patients affected by head and neck ENHL in the period between 2003 and 2017. All patients underwent a diagnostic-therapeutic procedure according to the guidelines, and a 5-year follow-up. Based on the location of the swelling at the time of diagnosis, patients were divided into two groups: oral and non-oral ENHLs. Statistical analysis was performed using Kaplan–Meier analysis with the log-rank test. In addition, Fisher’s exact test was applied to the two groups to evaluate and compare variances (the acceptable significance level was set at p < 0.05). Conclusion: ENHL with oral localization is much more aggressive than ENHL with non-oral localization, with a death rate of 40% (versus 4.76 for the non-oral one). In fact, between the two groups, there is a statistically significant difference in mortality, with a p-value of 0.0001 and 0.0002, respectively.  相似文献   
62.
The present study examined alterations of brain noradrenaline (NA) turnover as a function of preshock and psychological stress treatments, by measuring contents of NA metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), in discrete brain regions of male Wistar rats. Psychological stress induced by exposing to the sight, sound and odor of other rats being shocked produced higher levels of MHPG-SO4 in the hypothalamus, amygdala and locus coeruleus (LC) region, as well as higher levels of plasma corticosterone. Preshock experienced rats also showed marked increases of MHPG-SO4 levels in the same regions described above and elevated plasma corticosterone levels when placed but not shocked in the same environment in which the rats had previously received shocks. The effects of psychological stress on brain NA turnover were affected by the animal's shock history preferentially in the hypothalamus and amygdala. These results suggest that: a purely psychological stressor caused acutely enhanced NA turnover in specific brain regions; regional NA activity appeared to be reinstated simply by reexposure to the environment previously associated with shock; preshock experience further intensified the enhancement of amygdaloid NA turnover evoked by psychological stress. An additional experiment, studying the aftereffects of preshock experience, clearly showed that these findings result from sensitization or conditioning to the environment previously paired with shock, and not merely from the aftereffects of the shock per se.  相似文献   
63.
64.
Background and hypothesisPsychotic disorders have been associated with not being in education, employment, and training (NEET). There is a lack of knowledge on the importance of risk markers for NEET among people with psychotic disorders and what rehabilitation they receive.Study designWe based our research on the register-based 1987 Finnish Birth Cohort study, which included all live births in Finland during that year. The study cohort were 288 people who had been diagnosed with psychotic disorders during 2004–2007, when they were 16–20 year old, and 55 883 who had not. We looked at the national register data for those subjects in 2008–2015, when they were 20–28 year old, and compared any associations between sociodemographic factors and NEET status.Study resultsNEET for more than 5 year affected 2.2% of those without psychosis, 35.8% of those with any nonaffective psychotic disorder, and 57.0% of those with schizophrenia or schizoaffective disorders. Family-related risk factors were weaker predictors of long-term NEET in subjects with psychotic disorders than other cohort members. Having a psychotic disorder plus long-term NEET was associated with not applying for upper secondary education, not finishing upper secondary education, parents receiving welfare benefits, being diagnosed with schizophrenia or schizoaffective disorders and being hospitalized for psychosis. Only 24.3% with psychotic disorders had participated in vocational rehabilitation.ConclusionsA diagnosis of psychosis in adolescence is independently associated with serious long term functional disability. Among those with psychotic disorders, educational problems are markers for adverse labor market outcomes. Despite this, vocational rehabilitation is seldom provided.  相似文献   
65.
The fluorescence spectral fingerprint, also known as the excitation-emission matrix (EEM), is used to assess and visualize therapeutic drug photodegradation in combination with chemometrics. Examination of EEM-parallel factor analysis (PARAFAC) data showed that an individual component was easily separated from a mixture of photogenerated products of a heterocyclic pharmacophore, in this case, phenothiazine drugs (PTZs). Detailed investigations of both structure–EEM relationships and kinetics revealed that the components extracted from EEM–PARAFAC could be quantitatively attributed to such photogenerated products as phenothiazine sulfoxide and carbazole derivatives. EEM in combination with principal component analysis (PCA) could be used as a mapping tool to visualize information of the photodegradation process of PTZs. We also assessed the photostability of various types of PTZs containing side chains by using validated EEM–PARAFAC methodology.

Drug quality and assurance changes with time under the influence of a variety of environmental factors, such as light, temperature, and moisture.  相似文献   
66.
Herpes Simplex Virus type 1 (HSV‐1) is a very common infection often localized in the mucocutaneous junction of the lip. Rarely, it could be detected also in periodontal tissues, associated with an elevated risk of periodontal disease progression and gingival recessions. Recently, HSV‐1 and numerous co‐infections have been reported in literature associated with the Coronavirus and subsequent COVID‐19 disease. This report illustrates a case of HSV‐1 in a patient with Covid‐19 infection, showing the presence of ulcers and vesicles on the gingival margin of maxillary teeth associated with soreness and pain. The histology highlighted the presence of intraepithelial cell ballooning, confirming the diagnosis of HSV‐1 infection.  相似文献   
67.
68.
69.
70.
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