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   21558篇
  免费   1878篇
  国内免费   787篇
耳鼻咽喉   209篇
儿科学   400篇
妇产科学   233篇
基础医学   1922篇
口腔科学   652篇
临床医学   2513篇
内科学   2946篇
皮肤病学   195篇
神经病学   1064篇
特种医学   1031篇
外国民族医学   26篇
外科学   2588篇
综合类   3577篇
现状与发展   5篇
一般理论   2篇
预防医学   2001篇
眼科学   361篇
药学   2167篇
  23篇
中国医学   1184篇
肿瘤学   1124篇
  2024年   55篇
  2023年   212篇
  2022年   493篇
  2021年   662篇
  2020年   534篇
  2019年   386篇
  2018年   387篇
  2017年   478篇
  2016年   379篇
  2015年   656篇
  2014年   885篇
  2013年   1133篇
  2012年   1489篇
  2011年   1674篇
  2010年   1404篇
  2009年   1249篇
  2008年   1461篇
  2007年   1344篇
  2006年   1229篇
  2005年   1036篇
  2004年   800篇
  2003年   785篇
  2002年   666篇
  2001年   547篇
  2000年   536篇
  1999年   330篇
  1998年   143篇
  1997年   120篇
  1996年   98篇
  1995年   108篇
  1994年   77篇
  1993年   65篇
  1992年   183篇
  1991年   177篇
  1990年   174篇
  1989年   157篇
  1988年   155篇
  1987年   143篇
  1986年   142篇
  1985年   142篇
  1984年   103篇
  1983年   87篇
  1982年   71篇
  1981年   60篇
  1979年   65篇
  1978年   63篇
  1977年   58篇
  1976年   58篇
  1974年   68篇
  1973年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
The LY-1 gene expression in murine hybridomas producing autoantibodies   总被引:1,自引:0,他引:1  
  相似文献   
73.
Rates in vitro changes of gonococcal colony opacity phenotypes.   总被引:10,自引:9,他引:10       下载免费PDF全文
The rate of change of colony opacity phenotype was determined for 12 strains of Neisseria gonorrhoeae. The average rate of change was about 2 X 10(-3) per colony-forming unit per generation with a range of 0.2 X 10(-3) to 4 X 10(-3) per colony-forming unit per generation. Transition from opaque to transparent occurred at the same rate as transition from transparent to opaque. The following factors were shown to have no effect on the transition rate: (i) the state of piliation; (ii) the number of passages as a particular phenotype; (iii) alteration in the temperature, pH, or amount of oxygen in the atmosphere during growth; (iv) the addition of any of 194 compounds or mixtures to the growth media; (v) the addition of DNase or of DNA from opaque or transparent gonococci; and (vi) incubation between the opacity-transparency transition and the change resulting in the loss of piliation was seen. Some implications of the high transition rate are discussed.  相似文献   
74.
Infliximab for the treatment of fistulas in patients with Crohn's disease   总被引:38,自引:0,他引:38  
BACKGROUND: Enterocutaneous fistulas are a serious complication of Crohn's disease and are difficult to treat. Infliximab, a chimeric monoclonal antibody to tumor necrosis factor alpha, has recently been developed as a treatment for Crohn's disease. We conducted a randomized, multicenter, double-blind, placebo-controlled trial of infliximab for the treatment of fistulas in patients with Crohn's disease. METHODS: The study included 94 adult patients who had draining abdominal or perianal fistulas of at least three months' duration as a complication of Crohn's disease. Patients were randomly assigned to receive one of three treatments: placebo (31 patients), 5 mg of infliximab per kilogram of body weight (31 patients), or 10 mg of infliximab per kilogram (32 patients); all three were to be administered intravenously at weeks 0, 2, and 6. The primary end point was a reduction of 50 percent or more from base line in the number of draining fistulas observed at two or more consecutive study visits. A secondary end point was the closure of all fistulas. RESULTS: Sixty-eight percent of the patients who received 5 mg of infliximab per kilogram and 56 percent of those who received 10 mg per kilogram achieved the primary end point, as compared with 26 percent of the patients in the placebo group (P=0.002 and P=0.02, respectively). In addition, 55 percent of the patients assigned to receive 5 mg of infliximab per kilogram and 38 percent of those assigned to 10 mg per kilogram had closure of all fistulas, as compared with 13 percent of the patients assigned to placebo (P=0.001 and P=0.04, respectively). The median length of time during which the fistulas remained closed was three months. More than 60 percent of patients in all the groups had adverse events. For patients treated with infliximab, the most common were headache, abscess, upper respiratory tract infection, and fatigue. CONCLUSIONS: Infliximab is an efficacious treatment for fistulas in patients with Crohn's disease.  相似文献   
75.
Punch grafting and flap surgery are proven methods of correcting baldness. Using either method, the location and shape of a new hairline on the frontal and temporal scalp is one of the most important aspects of hair replacement surgery. If the hairline is not aesthetic, the results can be unacceptable or even devastating for the patient and surgeon alike. The principles of planning the frontal and temporal hairline are presented using punch grafts as well as flaps. Postoperative styling of the "new" hair will vary depending upon the method used to transfer the hair (flaps or grafts), the local factors involved (texture, direction, density, tufting, etc.), as well as the patient's preference. The various advantages and disadvantages of styling possibilities with each method are presented. These factors should be discussed with the patient preoperatively.  相似文献   
76.
Summary Patients with malignant disease may be predisposed to bacterial infections because of neoplastic disruption of normal tissue barriers, exogenous immunosuppressive therapy (drugs with or without radiation), and intrinsic host immune deficits secondary to these diseases. Diminished polymorphonuclear leukocyte numbers or function and impaired humoral immunity are highly correlated with the development of serious bacterial infections. The usual signs and symptoms of infection may be absent or altered in a compromised host.Therapy must be instituted promptly upon clinical suspicion of bacterial infection, and empirical choices should usually include combinations that are synergistic for likely pathogens based on knowledge of the local predominant flora and susceptibility data. Synergism has most often been demonstrated in combinations that utilize a -lactam (semisynthetic penicillin or cephalosporin) and an aminoglycoside. Triple drug therapy has not been shown to be advantageous. Monotherapy with third generation cephalosporins, carbapenems, monobactams, or ureidopenicillins has not been proven to offer advantages over 2-drug regimens for these patients.Patients with blood deficient in granulocytes (granulocytopenic) who respond to 2-drug therapy but remain deficient in neutrophils (neutropenic) may need continued treatment until the neutropenia subsides. Those who do not respond and remain febrile with an unclear focus of infection may need to be started on antifungal therapy in addition to the antibacterial agent. The use of oral agents for the prophylaxis of neutropenic patients against bacteremia remains controversial. If drugs are used, co-trimoxazole and nystatin suspension may be preferable.  相似文献   
77.
目的研究脂肪组织中高迁移率族蛋白B1(HMGB1)表达增加与妊娠期糖尿病(GDM)患者胰岛素抵抗程度及产后糖代谢异常的关系。方法选择2016年10月至2019年3月期间在海安市中医院诊断为GDM并接受剖宫产的126例患者作为GDM组,选择同期在该院接受剖宫产的健康孕妇150例作为对照组,检测剖宫产当天孕妇血清HMGB1、空腹胰岛素(FINS)的含量及脂肪组织中HMBG1、胰岛素受体底物(IRS)-1、IRS-2的表达水平,计算胰岛素抵抗指数(HOMA-IR)。随访产后1年内糖代谢异常的发生情况并绘制K-M曲线。结果GDM组患者脂肪组织中HMGB1的表达水平、血清HMGB1含量及FINS、HOMA-IR水平明显高于对照组(t值分别为14.496、16.503、19.068、13.446,P<0.05),脂肪组织中IRS-1、IRS-2的表达水平明显低于对照组(t值分别为11.616、10.596,P<0.05);GDM组患者脂肪组织中HMGB-1的表达水平与血清HMGB1、FINS的含量及HOMA-IR的水平呈正相关(r值分别为0.405、0.358、0.405,P<0.05),与脂肪组织中IRS-1、IRS-2的表达水平呈负相关(r值分别为-0.278、0.255,P<0.05);经K-M曲线分析,与GDM组中脂肪组织HMGB1低表达患者比较,HMGB1高表达患者产后1年糖代谢异常累积发生率明显升高(χ^(2)=3.933,P<0.05)。结论GDM患者脂肪组织中HMGB1表达增加与胰岛素抵抗的加重、产后糖代谢异常的发生有关。  相似文献   
78.
79.
80.
Modified Allen pictures to assess amblyopia in young children   总被引:1,自引:0,他引:1  
D L Mayer  R D Gross 《Ophthalmology》1990,97(6):827-832
To produce a test of visual acuity for young children that is more sensitive to amblyopia than current preschool vision tests, the authors surrounded four Allen pictures with "crowding" bars. This modified Allen test was evaluated by measuring acuity of amblyopic children (n = 28) and children (n = 10) and adults (n = 5) with normal eyes. Mean acuities of amblyopic eyes for the modified pictures was 0.8 octaves or nearly three logMar Snellen lines poorer than for the isolated pictures. For nonamblyopic and normal eyes modified picture acuity averaged 0.1 to 0.4 octaves poorer than isolated picture acuity. Average acuities of amblyopic eyes (n = 22) for the modified pictures agreed with line letter acuities. These results suggest that the modified picture test induces contour interaction similar to that of line letter tests, and thus, is a more sensitive test of amblyopia in the preschool child than isolated symbols.  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