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   2038篇
  免费   123篇
  国内免费   75篇
耳鼻咽喉   1篇
儿科学   172篇
妇产科学   26篇
基础医学   239篇
口腔科学   58篇
临床医学   256篇
内科学   514篇
皮肤病学   76篇
神经病学   63篇
特种医学   391篇
外科学   91篇
综合类   44篇
预防医学   92篇
眼科学   19篇
药学   85篇
  2篇
肿瘤学   107篇
  2023年   4篇
  2022年   3篇
  2021年   11篇
  2020年   14篇
  2019年   15篇
  2018年   31篇
  2017年   22篇
  2016年   22篇
  2015年   39篇
  2014年   47篇
  2013年   58篇
  2012年   36篇
  2011年   39篇
  2010年   88篇
  2009年   85篇
  2008年   52篇
  2007年   89篇
  2006年   53篇
  2005年   54篇
  2004年   29篇
  2003年   22篇
  2002年   32篇
  2001年   39篇
  2000年   36篇
  1999年   31篇
  1998年   129篇
  1997年   156篇
  1996年   134篇
  1995年   108篇
  1994年   116篇
  1993年   97篇
  1992年   29篇
  1991年   37篇
  1990年   38篇
  1989年   55篇
  1988年   51篇
  1987年   42篇
  1986年   50篇
  1985年   46篇
  1984年   27篇
  1983年   16篇
  1982年   25篇
  1981年   29篇
  1980年   26篇
  1979年   4篇
  1978年   8篇
  1977年   20篇
  1976年   25篇
  1975年   14篇
  1966年   1篇
排序方式: 共有2236条查询结果,搜索用时 31 毫秒
941.
942.
Pesando  JM; Hoffman  P; Martin  N; Conrad  T 《Blood》1986,67(3):588-591
The common acute lymphoblastic leukemia antigen (CALLA) is a 100-kd surface glycoprotein that is present on normal and malignant lymphoid cells. It is a useful marker for distinguishing between clinically important types of acute leukemia. Anti-CALLA monoclonal antibodies (MoAb) also react with mature myeloid cells (granulocytes), where they identify an antigen having a similar molecular weight (mol wt). We now report that the antigens detected by anti-CALLA MoAb on human lymphoid and myeloid cells differ in their behavior and chemistry. Surface- labeling studies indicate that the antigen on lymphoid cells has a mol wt of approximately 100 kd v 110 kd for that on granulocytes. When cells are metabolically labeled with 35S-methionine, differences in the mol wt of these antigens are again observed. Unlike the lymphoid antigen, expression of that on purified granulocytes is not modulated by incubation with specific antibody. Sodium dodecyl sulfate- polyacrylamide gel electrophoresis analysis of proteolytic digests of the two antigens fails to clarify their chemical relationship. Thus the antigens detected on these two cell types may share an epitope(s) but be chemically distinct, or CALLA may exist in distinct forms and behave differently on lymphoid cells and granulocytes.  相似文献   
943.
944.
CT findings in Swyer-James syndrome   总被引:4,自引:0,他引:4  
Swyer-James syndrome (SJS) is usually diagnosed with plain chest radiographs obtained during inspiration/expiration. The authors studied patients with CT to assess its value in the evaluation of this syndrome. In patients with SJS, CT was useful in the determination of bronchial patency (all nine patients), lung parenchymal changes (subpleural infiltrates in six patients, atelectasis in two, and cavities in two), and the extent and degree of bronchiectasis (all nine patients). If CT is used for the evaluation of bronchiectasis, knowledge of the main findings associated with SJS (hyperlucent lung without anteroposterior gradient attenuation [n = 8], small lung [n = 6], and diminished central and peripheral pulmonary arteries [n = 9]) should facilitate the diagnosis of associated SJS. Expiration CT would support the diagnosis with demonstration of air trapping.  相似文献   
945.
The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.  相似文献   
946.
947.
应用导数光谱法考察苯呋洛尔溶液体外经皮渗透性   总被引:1,自引:0,他引:1  
杨丽  郑俊民 《药学学报》1990,25(12):916-919
本文应用二阶导数紫外分光光度法考察了苯呋洛尔溶液体外经皮渗透性。考察了促进剂月桂氮(?)酮-丙二醉及PEG-400溶剂对其渗透性的影响。应用二阶导数紫外分光光度法消除了兔皮溶出物对一般紫外测定方法的干扰。结果表明:苯呋洛尔溶液具有体外经皮渗透性;月桂氮(?)酮-丙二醇系统及PEG-400均能增强苯呋洛尔溶液的体外经皮渗透性。  相似文献   
948.
949.
Weinreb  JC; Cohen  JM; Maravilla  KR 《Radiology》1985,156(2):435-440
Magnetic resonance (MR) imaging was performed on 15 healthy subjects to define the appearance of the iliopsoas muscle and on 15 patients with iliopsoas disease. Seven patients had tumorous involvement of the muscles, five had inflammatory disease, one had retroperitoneal hemorrhage, one had iliopsoas bursitis, and one had bilateral hypertrophy. MR imaging permitted delineation of the muscles and depiction of the disease condition. Transverse MR images alone almost always provided the necessary data to determine the origin and extent of disease. Sagittal images were occasionally useful in defining the extension of disease into the spine. T1-weighted images provided optimal contrast between the muscles and adjacent tissues, while T2-weighted images were more useful for depicting disease within the muscles themselves.  相似文献   
950.
To ascertain the optimal treatment for carcinoma of the piriform sinus, the authors determined survival rates and local and regional tumor growth for two groups of patients: those treated by radiation therapy alone (n = 209) and those treated by radiation therapy combined with surgery (n = 154). The two groups were similar with respect to the characteristics of primary tumor stage and degree of nodal involvement. The overall 3-year and 5-year actuarial survival rates were 19.2% and 15.5%, respectively. For 5-year actuarial survival, there was no significant difference between patients with T1 and T2 tumors, but there was a significant difference between patients with T1 + T2 tumors versus those with T3 tumor. There was no significant difference in 3- and 5-year survival between patients with N0 and N1 nodal involvement and those with N1 and N2 involvement, but there was a significant difference between patients with N0 versus those with N3 involvement. The 5-year actuarial survival rate is significantly better for patients who underwent surgery followed by radiation therapy than for those who received only radiation therapy. However, for patients with early-stage (T1 and T2) tumors, radiation therapy alone controls local tumor growth as well as the combination of surgery and radiation therapy does. For each treatment group, the causes of death and patterns of failure were studied and compared with investigations to date.  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