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   9053篇
  免费   859篇
  国内免费   32篇
耳鼻咽喉   77篇
儿科学   237篇
妇产科学   170篇
基础医学   1385篇
口腔科学   189篇
临床医学   960篇
内科学   2094篇
皮肤病学   123篇
神经病学   745篇
特种医学   317篇
外科学   1246篇
综合类   218篇
一般理论   7篇
预防医学   877篇
眼科学   95篇
药学   668篇
中国医学   4篇
肿瘤学   532篇
  2021年   130篇
  2019年   110篇
  2018年   120篇
  2016年   84篇
  2015年   124篇
  2014年   165篇
  2013年   230篇
  2012年   334篇
  2011年   398篇
  2010年   210篇
  2009年   213篇
  2008年   326篇
  2007年   314篇
  2006年   344篇
  2005年   348篇
  2004年   317篇
  2003年   303篇
  2002年   274篇
  2001年   312篇
  2000年   289篇
  1999年   272篇
  1998年   180篇
  1997年   117篇
  1996年   141篇
  1995年   97篇
  1994年   104篇
  1993年   99篇
  1992年   234篇
  1991年   225篇
  1990年   217篇
  1989年   193篇
  1988年   208篇
  1987年   187篇
  1986年   210篇
  1985年   197篇
  1984年   144篇
  1983年   155篇
  1982年   103篇
  1981年   102篇
  1980年   79篇
  1979年   144篇
  1978年   135篇
  1977年   109篇
  1976年   113篇
  1975年   103篇
  1974年   118篇
  1973年   107篇
  1970年   79篇
  1969年   74篇
  1968年   73篇
排序方式: 共有9944条查询结果,搜索用时 15 毫秒
61.
62.
Plasmacytoid T-cell lymphoma (PTL) is a rare lymphoma with unique morphologic, immunologic, and clinical features. Thus far, only three cases have been reported, each terminating in myeloid leukemia. The macrophage/monocyte rather than T-cell origin of "plasmacytoid T-cells" in reactive lymph nodes has been suggested in the past, but there has been no extensive investigation to demonstrate whether the PTLs are also of this lineage. The authors now report on a patient with PTL who had a long history of clinically stable idiopathic myelofibrosis. Immunocytochemical staining of the neoplastic plasmacytoid cells, with a large panel of monoclonal antibodies used on fresh-frozen and paraffin-embedded tissue sections, showed that the neoplastic cells expressed several macrophage/monocyte-associated markers, i.e., CD31, CD36 (thrombospondin receptor), and CD68 (KP1). Other markers of the macrophage/monocyte lineage (e.g., CD11b, CD11c, CD16) were absent. The neoplastic cells lacked B-cell-associated antigens and lacked most T-cell-associated markers, with the exception of CD2 and CD4. These findings are in close agreement with those of previous studies on normal plasmacytoid T-cells and support the macrophage/monocytic origin of PTL. Molecular hybridization studies provided additional support for the nonlymphoid origin of the plasmacytoid cells by demonstrating the absence of T-cell-receptor beta-chain and immunoglobulin heavy-chain gene rearrangements in the neoplastic cells. The results of the authors' studies indicate that "plasmacytoid T-cell lymphoma" associated with a chronic myeloproliferative disorder is of macrophage/monocyte lineage.  相似文献   
63.
Structure of the corpus luteum in the ovulatory polycystic ovary.   总被引:2,自引:0,他引:2  
BACKGROUND: Women with polycystic ovaries (PCO) have a wide spectrum of presentation from anovulation and amenorrhoea to apparently regular, ovulatory menstrual cycles. We have recently reported a subtle defect in steroidogenic function in the luteal phase in the latter and an increase in the number of degenerating corpora lutea (CL) were observed in ovulatory PCO (ovPCO) during dissection. The possibility was therefore investigated of differences in structure or degeneration in CL formed during ovulatory cycles in women with PCO. METHODS: This study compared the histology of the CL in ovPCO with that in the normal ovary. Corpora lutea were collected from nine normal ovaries (days 1-27 of the cycle) and from 13 women with ovPCO (days 5-38). RESULTS: Variations in the degree of regression, both in relation to onset of menses and between different areas within individual CL, were recorded in both groups. During development and regression no obvious differences were observed between either group apart from an apparent increase in luteal haemorrhage, which was more common and more extensive in CL from PCO. CONCLUSIONS: The findings suggest that possible luteal phase abnormalities of steroid secretion in women with ovulatory PCO are not associated with obvious morphological defects in the CL, however it is possible that the persistence of luteal structures seen in PCO was a consequence of increased luteal haemorrhage.  相似文献   
64.
BACKGROUND: The incidence of leiomyomas in pregnancy is approximately 1%. Their presence has been linked to spontaneous abortion, premature labor, soft tissue dystocia, uterine inertia, fetopelvic disproportion, malposition of the fetus, retention of the placenta, and postpartum hemorrhage. CASE: This case report documents a seldom-described event of a submucous leiomyoma masquerading as retained products of conception. The patient presented 4 weeks postpartum with complaints of urinary retention and heavy bleeding with cramping. Examination revealed a large mass resembling placental tissue filling the vaginal vault. The necrotic mass was removed with blunt and sharp dissection. The final pathology report revealed a degenerating leiomyoma. CONCLUSION: Complicating factors associated with this fibroid included a history of spontaneous abortion and preterm labor, as well as fetal malpresentation and carneous degeneration of the leiomyoma. Gestational myomas, although rare, can have an unusual appearance that may be misinterpreted.  相似文献   
65.
Thirteen cases of disseminated Mycobacterium avium-intracellulare (MAI), representing a total of 27 bone marrow specimens, were studied. The patients ranged from 25 to 46 years of age and included ten immunocompromised and three immunocompetent hosts. Peripheral blood findings included anemia in all patients, leukopenia in 73%, thrombocytopenia in 45%, and pancytopenia in 45%. Fourteen of the specimens (52%) showed granulomas ranging from small, subtle lymphohistiocytic aggregates to larger lymphohistiocytic lesions and clusters of epithelioid histiocytes; almost half of these lesions were missed initially. Rare acid-fast bacilli were seen in only one case, but 53% grew MAI on culture. In one case of the acquired immunodeficiency syndrome, culture was positive in the absence of inflammation or AFB on staining. These findings are not significantly different from those reported in disseminated Mycobacterium tuberculosis infection.  相似文献   
66.
67.
J W Mason 《Psychosomatic medicine》1968,30(5):Suppl:576-Suppl:607
  相似文献   
68.
The oral flora of 10 patients with Sjögren''s syndrome was compared with that of 10 healthy control subjects. Significantly greater numbers of Candida albicans, Staphylococcus aureus, and coliform bacilli were present in the Sjögren''s group. Possible reasons for these changes are discussed.  相似文献   
69.
Regression of v-src DNA-induced sarcomas is under host genetic control.   总被引:1,自引:0,他引:1  
Previous results have established that subcutaneous inoculation of chickens (line SC) with a v-src(+) subviral DNA fragment induces the formation of progressor sarcomas at the wing web site of inoculation. Because the sarcoma cells are incompetent for production of exogenous progeny virus, this system is a useful model of tumor expansion by sarcoma cell division, in the absence of infection-mediated recruitment of new tumor cells. The present study was undertaken to define conditions that modulate the pattern of growth (regression vs progression) of v-src DNA-induced sarcomas. These conditions were found to include the line of chicken or the presence on the subviral v-src(+) DNA fragment of a viral replication-specific sequence that includes env.  相似文献   
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