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   2023篇
  免费   109篇
  国内免费   76篇
耳鼻咽喉   1篇
儿科学   171篇
妇产科学   26篇
基础医学   226篇
口腔科学   58篇
临床医学   255篇
内科学   492篇
皮肤病学   73篇
神经病学   59篇
特种医学   392篇
外科学   98篇
综合类   44篇
一般理论   1篇
预防医学   87篇
眼科学   26篇
药学   89篇
  2篇
肿瘤学   108篇
  2023年   5篇
  2022年   7篇
  2021年   13篇
  2020年   15篇
  2019年   15篇
  2018年   32篇
  2017年   22篇
  2016年   22篇
  2015年   39篇
  2014年   47篇
  2013年   59篇
  2012年   36篇
  2011年   39篇
  2010年   88篇
  2009年   86篇
  2008年   50篇
  2007年   89篇
  2006年   51篇
  2005年   54篇
  2004年   24篇
  2003年   18篇
  2002年   29篇
  2001年   36篇
  2000年   31篇
  1999年   32篇
  1998年   131篇
  1997年   157篇
  1996年   132篇
  1995年   110篇
  1994年   114篇
  1993年   97篇
  1992年   28篇
  1991年   35篇
  1990年   36篇
  1989年   55篇
  1988年   47篇
  1987年   42篇
  1986年   49篇
  1985年   45篇
  1984年   26篇
  1983年   15篇
  1982年   24篇
  1981年   29篇
  1980年   25篇
  1979年   4篇
  1978年   8篇
  1977年   18篇
  1976年   25篇
  1975年   14篇
  1966年   1篇
排序方式: 共有2208条查询结果,搜索用时 15 毫秒
61.
62.
Pesando  JM; Conrad  TA 《Blood》1984,64(5):1074-1078
Serologic studies using four murine monoclonal antibodies specific for the common acute lymphoblastic leukemia antigen (CALLA) and five monoclonal antibodies specific for the gp24 surface antigen indicate that these leukemia-associated antigens are present on cells of comparable tissues in man and in four nonhuman primates. As in man, adherent cell populations obtained from skin, lung, and bone marrow of Macaca fascicularis, M mulatta, M nemestrina, and Papio cynocephalus react with these antibodies. Similarly, granulocytes from both man and these nonhuman primates bind CALLA- and gp24-specific antibodies. Radioimmune precipitation experiments confirm the identity of these antigens. Our studies suggest that nonhuman primates can be used to screen serologic reagents to leukemia-associated antigens for potential toxic effects on normal tissues prior to their use in man. Similarly, nonhuman primates could be employed to assess the possible role of antigen-positive stromal cells in the reconstitution of bone marrow following transplantation.  相似文献   
63.
Fifty-two patients with stage III or IV nodular mixed lymphocytic- histiocytic lymphoma (NM) were entered on a prospective randomized trial comparing cyclophosphamide-prednisone (CP) to either COPP (cyclophosphamide, vincristine, procarbazine, prednisone) or BCVP (BCNU, cyclophosphamide, vincristine, prednisone). The COPP regimen utilized in this Eastern Cooperative Oncology Group (ECOG) trial was similar to the four-drug regimen C-MOPP reported by the National Cancer Institute to achieve prolonged relapse-free survival in this histology. No significant differences in complete response rates, response duration, or overall survival were noted among the three regimens. A pattern of continuous late relapse was observed for all three chemotherapy programs. Although 11 of the 18 (61%) COPP patients achieved a complete response, only 3/11 (27%) remain disease-free with a median follow-up of over 3 yr. However, two of these three long-term complete responders have died with no clinical evidence of recurrent disease. The COPP patients received 84% of the calculated ideal doses of cyclophosphamide and 78% of the ideal dosage of procarbazine. Grade 3-4 hematologic toxicity was noted in 22% of the COPP group, 36% with BCVP, and 0% for the CP patients. We were unable to confirm the ability of COPP to achieve durable complete remissions in NM lymphoma. The cyclophosphamide-prednisone combination was equally effective when compared with COPP and BCVP, but produced minimal toxicity.  相似文献   
64.
Oral Diseases (2010) 17 , 115–122 Objective: To determine whether oral rinse matrix metalloproteinase (MMP)‐8 levels, measured by three different methods, tissue inhibitor of matrix metalloprotease‐1 (TIMP‐1) levels and elastase activity differentiate subjects with different periodontal condition; and second, to find out if MMP‐8 levels were comparable among the methods used. Methods: MMP‐8 levels were analysed with an immunofluorometric method (IFMA), dentoELISA and commercial ELISA. Also TIMP‐1 levels and elastase activity were measured. For statistical analysis 214 study subjects were categorized into four groups, specified by the presence and number of moderate (4–5 mm) and deep (≥6 mm) periodontal pockets, and bleeding on probing percentage. Results: MMP‐8 levels especially measured by dentoELISA and adjusted to the number of teeth per subject differentiated the study group with strong periodontal inflammatory burden from groups with lower levels. This was also verified with receiver operating characteristic ( ROC) analysis. Elastase activity associated with higher IFMA and dentoELISA MMP‐8 levels. IFMA MMP‐8/TIMP and dentoELISA MMP‐8/TIMP‐1 tended to be higher with the increasing level of periodontal inflammatory burden. TIMP‐1 levels decreased with increasing age. Conclusions: Oral rinse MMP‐8 together with TIMP‐1 analysis may have potential in complementary periodontal diagnostics. dentoELISA can be applied in quantitative oral rinse chair side biomarker diagnostics.  相似文献   
65.
66.
67.
68.
Cerebral microinfarcts (CMIs) are common neuropathologic findings in aging and dementia. We explored the spectrum of cortical CMIs that can be visualized with 7T magnetic resonance imaging (MRI). Thirty-three coronal brain slices of 11 individuals with neuropathologically confirmed dementia were subjected to a high-resolution postmortem 7T MRI protocol. First, we identified all visible small (⩽5 mm) intracortical and juxtacortical lesions on postmortem MRI. Lesions were classified as CMI or nonCMI based on histology, and their MR features were recorded. Thirty lesions were identified on the initial MRI evaluation, of which twenty-three could be matched with histology. Histopathology classified 12 lesions as CMIs, all of which were located intracortically. On the basis of their MR features, they could be classified as chronic gliotic CMIs—with or without cavitation or hemorrhagic components—and acute CMIs. Eleven MRI identified lesions were not of ischemic nature and most commonly enlarged or atypically shaped perivascular spaces. Their MRI features were similar to gliotic CMIs with or without cavitation, but these ‘CMI mimics'' were always located juxtacortically. 7T postmortem MRI distinguishes different histopathologic types of cortical CMIs, with distinctive MR characteristics. On the basis of our findings, we propose in vivo rating criteria for the detection of intracortical CMIs.  相似文献   
69.
氯化四乙基铵及维拉帕米对家兔缺血心肌不应期的影响   总被引:1,自引:0,他引:1  
实验比较了K+通道阻断剂氯化四乙基铵(TEA)及Ca2+通道阻断剂维拉帕米(verapamil,Ver)对家兔缺血性心室肌不应期(ERP)的影响。结果表明,阻断冠脉10min及30min后,缺血中心区(CIZ)和缺血边缘区(BIZ)心肌ERP比缺血前均明显缩短,而TEA和Ver均能延长急性缺血性心肌的ERP,可能对心肌缺血引起的心律失常有预防作用。  相似文献   
70.
P53 gene mutations in acute myeloid leukemia with 17p monosomy   总被引:4,自引:2,他引:4  
We looked for mutations of exons 5 to 8 of the P53 gene in 10 patients with acute myeloid leukemia (AML) and 17p monosomy, and 36 patients with AML and no cytogenetic abnormalities of 17p. DNA was analyzed by polymerase chain reaction, single-strand conformation polymorphism analysis, and nucleotide sequencing. Four of the 10 patients with 17p monosomy showed point mutation, single-nucleotide deletion, or insertion in exons 7 or 8. By contrast, only 1 of the 36 patients with AML and no cytogenetic abnormalities of 17p showed a mutation of the P53 gene in exons 5 to 8 (P less than .01). These results suggest that alterations of the P53 gene may have a role in leukemogenesis in some cases of AML. The fact that P53 gene mutations occurred more often in patients with 17p monosomy seems to support the "recessive" model of tumor suppressive activity of the P53 gene rather than the "dominant" model, in which alteration of only one allele is sufficient for the development of malignancy.  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