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   1277465篇
  免费   92775篇
  国内免费   1993篇
耳鼻咽喉   18191篇
儿科学   42266篇
妇产科学   37836篇
基础医学   187104篇
口腔科学   35381篇
临床医学   108285篇
内科学   251622篇
皮肤病学   26503篇
神经病学   99226篇
特种医学   50022篇
外国民族医学   366篇
外科学   197775篇
综合类   26524篇
现状与发展   1篇
一般理论   301篇
预防医学   92628篇
眼科学   29060篇
药学   97830篇
  1篇
中国医学   2498篇
肿瘤学   68813篇
  2018年   11820篇
  2015年   11621篇
  2014年   16011篇
  2013年   24373篇
  2012年   33584篇
  2011年   35974篇
  2010年   21234篇
  2009年   20039篇
  2008年   35020篇
  2007年   37984篇
  2006年   38551篇
  2005年   37837篇
  2004年   36425篇
  2003年   35400篇
  2002年   34952篇
  2001年   58127篇
  2000年   59618篇
  1999年   50713篇
  1998年   14248篇
  1997年   12816篇
  1996年   13082篇
  1995年   12355篇
  1994年   11765篇
  1993年   10866篇
  1992年   41006篇
  1991年   40384篇
  1990年   39899篇
  1989年   38732篇
  1988年   36129篇
  1987年   35364篇
  1986年   33740篇
  1985年   32156篇
  1984年   23935篇
  1983年   20833篇
  1982年   12387篇
  1981年   10935篇
  1980年   10206篇
  1979年   22639篇
  1978年   15885篇
  1977年   13730篇
  1976年   12976篇
  1975年   14205篇
  1974年   16688篇
  1973年   16083篇
  1972年   15321篇
  1971年   14235篇
  1970年   13214篇
  1969年   12737篇
  1968年   11978篇
  1967年   10481篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
944.
945.
946.
WT-1 positivity has previously been noted in nonneoplastic endometrial stroma. In this study we examined WT-1 expression in endometrial stromal neoplasms to ascertain whether these tumors are immunoreactive and whether this antibody might be of value in the diagnosis of these lesions. We also stained cases of cellular and highly cellular leiomyomas to investigate whether WT-1 might be of value in distinguishing these from an endometrial stromal neoplasm. We compared WT-1 staining with CD10, desmin, alpha smooth muscle actin, h-caldesmon, and AE1/3, many of these antibodies being commonly used to distinguish between an endometrial stromal and a smooth muscle phenotype. Cases of ESN (n = 5), low grade ESS (n = 14), and cellular or highly cellular leiomyoma (n = 14) were stained with the aforementioned antibodies. Cases were scored on a scale of 0 to 4+, with 4+ cases exhibiting positivity of >50% of cells. Sixteen of 19 endometrial stromal neoplasms were positive with WT-1, most (14 of 16) with 4+ positivity. Staining was nuclear (5 cases), cytoplasmic (5 cases), or combined nuclear and cytoplasmic (6 cases). All endometrial stromal neoplasms exhibited 4+ staining with CD10. Staining for alpha smooth muscle actin was present in most cases (14 of 19) and desmin and h-caldesmon were positive in a smaller number of cases (8 and 2 respectively). There was 4+ positivity with desmin in only 1 case. The 2 cases that were h-caldesmon positive both exhibited 1+ staining (<5% cells positive). Six cases were positive with AE1/3, 1 with 4+ staining. Leiomyomatous neoplasms always exhibited 4+ staining with desmin and alpha smooth muscle actin and in most cases (12 of 14) with h-caldesmon. The other 2 cases exhibited 2+ positivity. Most cases (12 of 14) were positive with WT-1 (7 of 14 with 4+ staining) and CD10 (5 of 14 with 4+ positivity). One case was positive with AE1/3. We conclude that diffuse WT-1 positivity is characteristic of endometrial stromal neoplasms and that this may be of value in diagnosis. However, WT-1 is of limited use in the distinction between an endometrial stromal and a cellular leiomyomatous neoplasm because many of the latter are also positive. This study confirms the value of h-caldesmon in the distinction between an endometrial stromal neoplasm (almost always h-caldesmon negative) and a cellular leiomyomatous neoplasm (h-caldesmon positive). Although CD10 is positive in endometrial stromal neoplasms, the commonly observed immunoreactivity of cellular and highly cellular leiomyomas with this antibody limits its diagnostic usefulness. Desmin is useful as all leiomyomatous neoplasms exhibited diffuse positivity, whereas only a small number of endometrial stromal neoplasms were focally positive and only 1 case exhibited 4+ positivity. Smooth muscle actin is of limited value since most neoplasms studied were positive. The overlapping immunophenotype of endometrial stromal and leiomyomatous neoplasms may reflect the origin of both cell types from a common progenitor within the uterus.  相似文献   
947.
Chronically elevated levels of corticotropin-releasing factor (CRF) in transgenic mice overexpressing CRF in the brain (CRF-OE) appear to be associated with alterations commonly associated with major depressive disorder, as well as with sensorimotor gating deficits commonly associated with schizophrenia. In the present study, we tested the hypothesis that antipsychotics may be effective in normalizing prepulse inhibition (PPI) of acoustic startle in CRF-OE mice, which display impaired sensorimotor gating compared to wild-type (WT) mice. The typical antipsychotic haloperidol and atypical antipsychotic risperidone improved PPI in the CRF-OE mice, but were ineffective in WT mice. The atypical antipsychotic clozapine did not influence PPI in CRF-OE mice, but reduced gating in WT mice. This effect of clozapine in the CRF-OE mice may thus be regarded as a relative improvement, consistent with the observed effect of haloperidol and risperidone. As expected, the anxiolytic, nonantipsychotic chlordiazepoxide was devoid of any effect. All four compounds dose-dependently reduced the acoustic startle response irrespective of genotype. These results indicate that antipsychotic drugs are effective in improving startle gating deficits in the CRF-OE mice. Hence, the CRF-OE mouse model may represent an animal model for certain aspects of psychotic depression, and could be a valuable tool for research addressing the impact of chronically elevated levels of CRF on information processing.  相似文献   
948.
949.
Abstract – Traumatic dental injuries often occur to the teeth and their supporting tissues and they are the main reasons for emergency visit to a dental clinic. Management of a fracture depends on its position and the extent of root involvement. Horizontal root fractures are not seen frequently and the treatment consists of reduction and long‐term rigid fixation of the coronal segment. The present case demonstrates the successful management of two horizontally fractured maxillary central incisors with a follow‐up period of 9 months.  相似文献   
950.
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