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   701篇
  免费   56篇
  国内免费   96篇
耳鼻咽喉   4篇
儿科学   35篇
妇产科学   1篇
基础医学   89篇
口腔科学   20篇
临床医学   113篇
内科学   167篇
皮肤病学   18篇
神经病学   26篇
特种医学   109篇
外科学   34篇
综合类   36篇
预防医学   30篇
眼科学   18篇
药学   83篇
肿瘤学   70篇
  2023年   3篇
  2021年   8篇
  2019年   6篇
  2018年   7篇
  2017年   5篇
  2016年   5篇
  2015年   7篇
  2014年   11篇
  2013年   27篇
  2012年   15篇
  2011年   13篇
  2010年   34篇
  2009年   25篇
  2008年   19篇
  2007年   67篇
  2006年   24篇
  2005年   33篇
  2004年   11篇
  2003年   11篇
  2002年   18篇
  2001年   17篇
  2000年   15篇
  1999年   13篇
  1998年   42篇
  1997年   38篇
  1996年   31篇
  1995年   29篇
  1994年   29篇
  1993年   41篇
  1992年   9篇
  1991年   12篇
  1990年   13篇
  1989年   30篇
  1988年   27篇
  1987年   21篇
  1986年   18篇
  1985年   18篇
  1984年   17篇
  1983年   4篇
  1982年   10篇
  1981年   6篇
  1980年   12篇
  1979年   7篇
  1978年   5篇
  1977年   10篇
  1976年   3篇
  1975年   3篇
  1974年   2篇
  1973年   3篇
  1972年   2篇
排序方式: 共有853条查询结果,搜索用时 31 毫秒
111.
人参叶中微量新皂甙-La的分离与鉴定   总被引:4,自引:0,他引:4  
前已报道从人参(Panax ginseng C.A.Meyer)叶中分到三种微量新皂甙。在继续研究的基础上,又得到一个微量新皂甙,命名为人参皂甙-La(ginsenoside-La)。人参皂甙-La,无色针晶(MeOH),[α]D~(20)—18.4(Pyridine-d_5)。负离子FAB-MS  相似文献   
112.
Of 66 specimens from benign melanocytic nevi, including common acquired and congenital nevi, Spitz tumors (epithelioid cell nevi), and melanocytic nevi with dysplasia, 57 could be grown in tissue culture. The cultured cells were identified as melanocytes by the presence of premelanosomes and melanosomes. Cells from 28 of 32 nevus cultures grew in an anchorage-independent way in soft agar with a colony-forming efficiency between 0.001 and 1%. Clones derived from single cells and soft agar-selected colonies showed marked phenotypic heterogeneity, but all had a limited life span and did not undergo transformation in culture. These cells were nontumorigenic in nude mice. Cultured nevus cells expressed antigens present on melanoma but absent on normal fibroblasts and/or melanocytes as tested with monoclonal anti-melanoma antibodies. The anti-melanoma antibodies bound equally well to dysplastic, congenital, and common acquired nevi. Antigens are released by nevus cells similar to melanoma cells.  相似文献   
113.
114.
115.
116.
To investigate the influence of asymptomatic bacteriuria inchildhood on subsequent pregnancy, we reviewed the outcome of139 pregnancies in 88 women who were first identified duringa programme of screening schoolgirls for asymptomatic bacteriuriacarried out between 1970–1972 [1]. Data were analysedfor the following groups: 50 pregnancies in 28 women with knownrenal scars (group 1); 16 pregnancies in 14 women with normalkidneys and reflux (group 2); 73 pregnancies in 46 women withnormal urinary tracts (group 3); 139 healthy controls. Women in group 1 had a 3.3-fold increased relative risk of hypertension(p < 0.01) and a 7.6-fold increased risk of pre-eclampsia(p< 0.05) compared to controls, and a higher rate of obstetricinterventions, including emergency caesarean section. Womenin groups 2 and 3 appeared to carry a slightly increased riskof hypertension during the last trimester (RR = 1.8) but therewere no significant differences in this or the incidence ofpre-eclampsia or mode of delivery. Bacteriuria was more prevalentin all index groups compared to controls (37 per cent vs. 8per cent, p < 0.01) and included four cases of acute pyelonephritisin the study group. Fetal outcome was satisfactory in all cases.These results suggest that women with renal scars are at riskof hypertension and pre-eclampsia during pregnancy but thatmodern obstetric care minimizes these risks.  相似文献   
117.
Cytogenetic evidence for the clonal nature of Richter's syndrome   总被引:2,自引:0,他引:2  
Nowell  P; Finan  J; Glover  D; Guerry  D 《Blood》1981,58(1):183-186
Sequential chromosome studies were done on a patient who developed diffuse histiocytic lymphoma (DHL) after a long history of untreated chronic T-cell leukemia. During the indolent phase of her disease, a pseudodiploid lymphocyte population with 3q+ and 14q+ chromosome markers gradually replaced the originally diploid tumor cells. The karyotype of the lymphoma was hypertriploid (70--74 chromosomes) with the same 3q+ and 14q+ markers. The findings indicate that DHL in this patient evolved from the leukemic T-cell clone.  相似文献   
118.
Three primary and 16 metastatic melanoma cell lines were established from primary and metastatic lesions of 4 patients with malignant melanoma. Comparison of metastatic melanoma cells with cells of the vertical growth phase (VGP) or late primary melanoma from the same individual revealed, generally, a shorter population-doubling time, growth to a higher cell density, higher tyrosinase activity, and more pigmentation in metastatic cells. Conversely, primary and metastatic melanoma cells had similar morphology, plating efficiency, and tumorigenicity in nude mice. Karyotypic analysis revealed clonality and nonrandom abnormalities in chromosomes 1, 6, and 7 in cells of the primary and metastatic lesions of the 3 patients studied. Few differences were found in the expression of melanoma-associated antigens on short-term and long-term cultured cells by tests with monoclonal antibodies in mixed hemadsorption assays, flow cytometry, and radioimmunoassays. Our results indicate that cells cultured from the VGP but not from the radial growth phase of primary melanoma are similar to metastatic melanoma cells.  相似文献   
119.
120.
Superior mesenteric artery embolization: an angiographic emergency   总被引:1,自引:0,他引:1  
  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