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   924篇
  免费   53篇
  国内免费   46篇
耳鼻咽喉   2篇
儿科学   50篇
妇产科学   22篇
基础医学   105篇
口腔科学   38篇
临床医学   216篇
内科学   210篇
皮肤病学   11篇
神经病学   23篇
特种医学   116篇
外科学   66篇
综合类   12篇
预防医学   46篇
眼科学   4篇
药学   59篇
  1篇
肿瘤学   42篇
  2023年   5篇
  2022年   8篇
  2021年   10篇
  2020年   6篇
  2019年   11篇
  2018年   13篇
  2017年   14篇
  2016年   15篇
  2015年   17篇
  2014年   26篇
  2013年   38篇
  2012年   39篇
  2011年   36篇
  2010年   37篇
  2009年   29篇
  2008年   19篇
  2007年   53篇
  2006年   26篇
  2005年   16篇
  2004年   16篇
  2003年   18篇
  2002年   27篇
  2001年   18篇
  2000年   27篇
  1999年   16篇
  1998年   46篇
  1997年   52篇
  1996年   55篇
  1995年   46篇
  1994年   32篇
  1993年   33篇
  1992年   7篇
  1991年   17篇
  1990年   11篇
  1989年   16篇
  1988年   28篇
  1987年   21篇
  1986年   19篇
  1985年   15篇
  1984年   6篇
  1983年   8篇
  1982年   9篇
  1981年   8篇
  1980年   13篇
  1979年   8篇
  1978年   8篇
  1977年   9篇
  1975年   4篇
  1973年   2篇
  1970年   3篇
排序方式: 共有1023条查询结果,搜索用时 15 毫秒
31.
Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T- cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance.  相似文献   
32.
33.
The aim of this case report was to present a case of multiple calcified tuberculous lymph nodes found on a panoramic radiograph coincidently diagnosed in an endodontic clinic. A detailed discussion on the differential diagnosis of similar such calcification found in the same region is also presented. A 14‐year‐old girl was referred to our department with the complaint of painless swelling in the left side of the lower jaw. Clinical and radiographical examinations were performed, leading to the initial diagnosis of chronic periapical abscess. The patient's medical history was re‐evaluated. Advanced imaging and excisional biopsy were performed in order to confirm the final diagnosis. Regarding the presenting signs and symptoms of bilateral carious mandibular molars, a periapical inflammatory process was considered in the provisional diagnosis. A thorough examination and investigations were suggestive of cervical tuberculous lymphadenitis (scrofula), and the patient underwent excision of the same. The clinician should consider the possibility of chronic granulomatous inflammatory lesions in the differential diagnosis of radiopaque lesions.  相似文献   
34.
35.
目的研究新时期综合ICU患者的临床监护记录单,以保证患者及护士使用过程的便利及安全。方法将我院ICU自2002年使用的“图标式ICU监护记录单”,在原表格的基础上根据综合ICU患者需要多系统监测的特点进行修订,主要以数字和符号表示形式形成新的护理记录表格,并采取对比的方法考证新旧两种表格的效用。结果两种表格各项指标比较:相同人数的护士分别填写两种不同表格所使用的时间分别是新表格平均(66±11)min,旧表格平均(97±10)min,每份表格的分数设为100分,护理质量检查小组检查的结果,新表格平均(97±2)分,旧表格平均(94±2)分,两组时间及分数比较差异有统计学意义(t=10.6263,4.0307;P〈0.01);新旧表格使用合格率比较差异有统计学意义(90.12%比82.62%,x2=67.49,P〈0.01)。结论新的监护记录单更科学、更全面、简洁、更适合综合ICU不同种类的患者的记录要求,减轻护士工作量,减少记录时间,提高工作效率。  相似文献   
36.
Antigens of Fasciola hepatica adult worms were chromatographed using concanavalin A-Sepharose 4B. Two unbound peaks appeared in the inclusion volume (DT-1 and DT-2), and one peak was eluted with alpha-methylglucoside (E1-1). At least seven peaks were obtained by isoelectric focusing of E1-1. The largest of these peaks, with an average pI of 4.0, contained the antigens reactive with antibodies to Schistosoma mansoni. Mice immunized with DT-2 or E1-1 and challenged with S. mansoni cercariae developed 39 to 82% fewer worms than controls. DT-1 had no protective effect. Combining DT-1 and DT-2 abolished this protection. These experiments demonstrate that F. hepatica glycoprotein antigens induce in mice significant protection to infection with S. mansoni and offer an interesting approach to the study of vaccines in experimental schistosomiasis.  相似文献   
37.
Purpose.?To determine whether foot and leg problems are independently associated with functional status in a community sample of older people after adjusting for the influence of socio-demographic, physical and medical factors.

Method.?Data were analysed from the Health Status of Older People project, a population-based study involving a random sample of 1000 community-dwelling people aged 65?–?94 years (533 females, 467 males, mean age 73.4 years?±?5.87). A structured interview and brief physical examination were used to investigate the associations between self-reported foot and leg problems and functional status. Functional status was assessed using: (i) timed ‘Up & Go’ test, (ii) self-reported difficulty climbing stairs, (iii) self-reported difficulty walking one kilometer, (iv) self-reported difficulty performing instrumental activities of daily living (IADLs), and (v) self-reported history of one or more falls in the previous 12 months. These associations were then explored after adjusting for socio-demographic, physical and medical factors.

Results.?Thirty-six percent of the sample reported having foot or leg problems. Univariate analyses revealed that people with foot and leg problems were significantly more likely to exhibit poorer functional status in all parameters measured. After adjusting for socio-demographic, physical and medical factors, foot and leg problems remained significantly associated with impaired timed ‘Up & Go’ performance (OR?=?2.15, 95%CI 1.55?–?2.97), difficulty climbing stairs (OR?=?3.33, 95%CI 1.98?–?5.61), difficulty walking one kilometer (OR?=?3.13, 95%CI 2.09?–?4.69), and history of falling (OR?=?1.73, 95%CI 1.26?–?2.37).

Conclusions.?Foot and leg problems are reported by one in three community-dwelling people aged 65 years and older. Independent of the influence of age, gender, common medical conditions and other socio-demographic factors, foot and leg problems have a significant impact on the ability to perform functional tasks integral to independent living.  相似文献   
38.
Manometry of the alimentary tract is a valuable and widely used means to evaluate and diagnose the function of the alimentary tract. However, the measurement can be inconvenient due to the invasive method used, and the many factors affecting results. Research on colonic pressure data is even more insufficient. This paper deals with colonic pressure data via an improved method ensuring that pressure data of the whole colon is available. The data is analysed based on the learning vector quantization (LVQ) method. Testing results show that this method distinguishes the normal data and the abnormal data, consistently with the original diagnoses. This method can serve as an assistant diagnosis of colonic motility and contributes to further research on colonic motility based on pressure data.  相似文献   
39.
BB-10010 is a genetically engineered variant of human macrophage inflammatory protein-1 alpha with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of BB-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S12, and progenitors with marrow repopulating ability (MRA). A single subcutaneous dose of BB-10010 caused a twofold increase in circulating numbers of CFU-S8, CFU-S12, and MRA 30 minutes after dosing. We also investigated the effects of granulocyte colony-stimulating factor (G- CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-10010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA even further to 38-, 33-, and 100- fold. Splenectomy resulted in increased circulating progenitor numbers but did not change the pattern of mobilization. Two days of treatment with G-CSF then increased circulating CFU-S8, CFU-S12, and MRA by 64-, 69-, and 32-fold. A single BB-10010 administration after G-CSF treatment further increased them to 85-, 117-, and 140-fold, respectively, compared with control. We conclude that BB-10010 causes a rapid increase in the number of circulating hematopoietic progenitors and further enhances the numbers induced by pretreatment with G-CSF. BB- 10010 preferentially mobilized the more primitive progenitors with marrow repopulating activity, releasing four times the number achieved with G-CSF alone. Translated into a clinical setting, this improvement in progenitor cell mobilization may enhance the efficiency of harvest and the quality of grafts for peripheral blood stem cell transplantation.  相似文献   
40.
Tumor cells from eight adult patients with T-cell chronic malignancies were investigated with a series of monoclonal antibodies recognizing T- cell differentiation antigens. This series allowed definition of discrete subpopulations of mature T cells with functional specialization. All six patients with Sezary syndrome and one patient with T-chronic lymphocytic leukemia had cells with the same phenotype as normal helper/inducer T cells, whereas the other patient with T- chronic lymphocytic leukemia had cell with the same phenotype as normal cytotoxic/suppressor T cells. Some clinical manifestations observed in these patients may reflect retention of functional activities by their malignant cells.  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