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   1334篇
  免费   71篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   140篇
妇产科学   23篇
基础医学   171篇
口腔科学   30篇
临床医学   115篇
内科学   191篇
皮肤病学   37篇
神经病学   120篇
特种医学   195篇
外科学   149篇
综合类   9篇
预防医学   60篇
眼科学   17篇
药学   75篇
中国医学   5篇
肿瘤学   64篇
  2019年   12篇
  2018年   15篇
  2016年   19篇
  2014年   23篇
  2013年   21篇
  2012年   44篇
  2011年   44篇
  2010年   25篇
  2009年   21篇
  2008年   20篇
  2007年   41篇
  2006年   38篇
  2005年   50篇
  2004年   29篇
  2003年   27篇
  2002年   29篇
  2001年   48篇
  2000年   47篇
  1999年   45篇
  1998年   34篇
  1997年   29篇
  1996年   18篇
  1995年   29篇
  1994年   30篇
  1993年   29篇
  1992年   46篇
  1991年   42篇
  1990年   24篇
  1989年   38篇
  1988年   28篇
  1987年   30篇
  1986年   27篇
  1985年   26篇
  1984年   21篇
  1983年   19篇
  1982年   17篇
  1981年   16篇
  1980年   19篇
  1978年   15篇
  1977年   14篇
  1976年   21篇
  1975年   15篇
  1974年   22篇
  1973年   20篇
  1972年   29篇
  1971年   20篇
  1970年   11篇
  1969年   13篇
  1968年   12篇
  1967年   14篇
排序方式: 共有1407条查询结果,搜索用时 0 毫秒
41.
The first 100 consecutive shoulder arthroscopic procedures performed under interscalene anesthesia at a small community-sized military hospital are the basis of this report. This method of anesthesia was compared with 100 shoulder arthroscopies performed in a previous 2-year time period under general anesthesia. A variety of arthroscopic and subsequent open reconstructive procedures about the shoulder were performed using both techniques. Using the interscalene method, 87 regional blocks were entirely successful. Thirteen patients required conversion to general anesthesia for adequate pain control; however, 4 of these had a complete block in the recovery room and required no postoperative narcotics. Seven patients required supplementation with local anesthetic when an open procedure became necessary. There were no major complications. Minor complications included 5 patients with transient Horner's syndrome, 4 patients who experienced anxiety, which was controlled with sedation, and 3 with nausea or pruritus. Interscalene anesthesia provided excellent intraoperative and postoperative analgesia with low morbidity. On a subsequent questionnaire, all patients with a successful block reported that they were extremely satisfied with their experience. Ten patients who had previous shoulder surgery under general anesthesia preferred the interscalene method. In summary, interscalene anesthesia proved to be an excellent method of anesthesia for shoulder arthroscopy. The technique is reproducible within the resources available in most community-level hospitals.  相似文献   
42.
43.
As a preliminary step towards the use of cell surface single-chain class I major histocompatibility complex (MHC) molecules as T cell immunogens, we have engineered a recombinant gene encoding a full-length cell surface single-chain version of the H-2Dd class I MHC molecule (SCβDdm) which has β2-microglobulin (β2m) covalently linked to the amino terminus of a full-length H-2Dd heavy chain via a peptide spacer. The single-chain protein is correctly folded and stably expressed on the surface of transfected L cells. It can present an antigenic peptide to an H-2Dd-restricted antigen-specific T cell hybridoma. When expressed in peptide-transport-deficient cells, SCβDdm can be stabilized and pulsed for antigen presentation by incubation with extracellular peptide at 27° or 37 °C, allowing the preparation of cells with single-chain molecules that are loaded with a single chosen antigenic peptide. SCβDdm can be stably expressed in β2m-negative cells, showing that the single-chain molecule uses its own β2m domain to achieve correct folding and surface expression. Furthermore, the β2m domain of SCβDdm, unlike transfected free β2m, does not rescue surface expression of endogenous class I MHC in the β2m-negative cells. This strict cis activity of the β2m domain of SCβDdm makes possible the investigation of class I MHC function in cells, and potentially in animals, that express but a single type of class I MHC molecule.  相似文献   
44.
45.
Summary 1. Twenty-two patients with infectious mononucleosis were studied by liver biopsy and paper electrophoresis of the serum proteins. The findings were compared with a similar group of 30 patients with infectious hepatitis.2. The essential histologic features of infectious mononucleosis were the presence in the hepatic sinusoids and portal tracts of chronic inflammatory cells resembling small lymphocytes, with essentially no parenchymal cell damage. Admixed with this lymphocytic infiltrate, but in relatively minimal numbers, were a few plasma cells and polymorphonuclear leukocytes. In addition, in infectious mononucleosis there were, with rare exceptions, no lipochrome-containing Kupffer cells. Thus, in the majority of cases, the histologic picture was distinct from that seen in infectious hepatitis. Only in comparing a few of the more severe infectious mononucleosis cases with subsiding infectious hepatitis cases was there any tendency for the two pictures to merge, and the distinction on histologic grounds between the two entities could be made in the great majority of cases.3. The most commonly seen abnormalities in the paper electrophoretic patterns of sera obtained from patients with infectious mononucleosis were decreased albumin, increased gamma globulin, not infrequent but variable changes in alpha2 globulin, and the presence of abnormal proteins migrating with mobilities intermediate to alpha2 and beta, and beta and gamma globulins. The abnormalities observed in infectious hepatitis were similar to those of infectious mononucleosis, except that in hepatitis alpha2 globulin was decreased more consistently, gamma globulin increased less frequently, and beta globulin, which was normal in practically all the cases of infectious mononucleosis, was increased in a considerable number of cases.4. Treatment of patients with infectious mononucleosis need not include prolonged bed rest and restriction of activity in an effort to avoid the development of chronic liver disease.  相似文献   
46.
47.
The classification of urothelial neoplasms of the kidney traditionally has been similar to that of urinary bladder tumors. Several years ago, the classification of papillary urothelial neoplasms was revised. The current study focuses on the application of the 1998 World Health Organization (WHO)/International Society of Urological Pathology classification system to 102 renal pelvic urothelial neoplasms and compares it to the 1973 WHO classification scheme. In this study, all tumors were classified as urothelial carcinomas, and the majority (85%) were papillary. Most patients with papillary tumors presented with 'superficial' disease (< or = pT1). With the 1998 system, most papillary carcinomas were high grade, and were more often invasive as compared to low-grade tumors. Only 34% were low-grade papillary tumors and, of these, most (93%) were noninvasive. With the 1973 system, most papillary tumors were grade 2 or 3, with invasion more common in grade 3 tumors. By 1973 criteria, grade 2 tumors were a heterogeneous group; with 1998 criteria, nearly one-half were high grade and the other half low grade. The grade of papillary urothelial carcinomas with both the 1973 and 1998 grading methods was associated with stage (P=0.001). Our study reveals that papillomas and papillary urothelial neoplasms of low malignant potential are uncommon tumors in the kidney. Renal pelvic papillary urothelial neoplasms are most often carcinomas and are more commonly high grade than low grade. Although both the 1973 and 1998 systems showed a significant association with tumor stage, grade 2 papillary carcinomas are a heterogeneous group by 1973 criteria. The 1998 system provides useful information in that it more clearly defines a papillary tumor's grade and selects for a group of tumors, namely low-grade papillary urothelial carcinomas, for which a low likelihood of invasion can be predicted.  相似文献   
48.
CD8 can serve as a co-receptor or accessory molecule on the surface of CTL. As a co-receptor, CD8 can bind to the alpha3 domain of the same MHC class I molecules as the TCR to facilitate TCR signaling. To evaluate the role of the MHC class I molecule alpha3 domain in the activation of CD8(+) CTL, we have produced a soluble 227 mutant of H-2D(d), with a point mutation in the alpha3 domain (Glu227 --> Lys). 227 mutant class I-peptide complexes were not able to effectively activate H-2D(d)-restricted CD8 T cells in vitro, as measured by IFN-gamma production by an epitope-specific CD8(+) CTL line. However, the 227 mutant class I-peptide complexes in the presence of another MHC class I molecule (H-2K(b)) (that cannot present the peptide) with a normal alpha3 domain can induce the activation of CD8(+) CTL. Therefore, in order to activate CD8(+) CTL, the alpha3 domain of MHC class I does not have to be located on the same molecule with the alpha1 and alpha2 domains of MHC class I. A low-avidity CD8(+) CTL line was significantly less sensitive to stimulation by the 227 mutant class I-peptide complexes in the presence of the H-2K(b) molecule. Thus, low-avidity CTL may not be able to take advantage of the interaction between CD8 and the alpha3 domain of non-presenting class I MHC molecules, perhaps because of a shorter dwell time for the TCR-MHC interaction.  相似文献   
49.
Mucosal tissues are the primary route of transmission for most respiratory and sexually transmitted diseases, including human immunodeficiency virus. We aimed to generate strong mucosal immune responses to simian immunodeficiency virus (SIV) in rhesus macaques by targeting recombinant adenovirus serotype 5 (rAd5) to the lung. The immunogenicity and efficacy of aerosol (AE) vaccination was compared with intramuscular (IM) delivery in either an intravenous (IV) or intrarectal (IR) SIV(mac251) challenge model. Aerosolized rAd5 induced strong cellular responses in the lung and systemic humoral responses equivalent to IM. Strikingly, all immunization groups controlled acute viremia in the IV challenge model by 1-2 logs. By contrast, after IR challenge, only peak viremia was reduced by immunization, with no significant effect on SIV infection acquisition rate or mucosal CD4(+) T-cell preservation. Improved disease outcome was associated with pre-challenge cellular and humoral responses, while post-challenge T-cell responses were highly correlated with viremia control. The similar outcomes achieved by systemic and airway mucosal immunization support AE delivery as a safe, effective, and less invasive alternative to parenteral vaccination.  相似文献   
50.
Mucins are large highly glycosylated molecules that have been postulated to interfere with certain cell-cell interactions. Steric, charge and specific signalling effects have been postulated for the inhibition by cell-surface mucin molecules. In this report we evaluate the inhibitory effects of bovine submaxillary mucin (BSM), a mucin without specific lymphocyte interactions, on lymphocyte function. BSM inhibits the adhesion of lymphocytes when coimmobilized with intercellular adhesion molecule-1 (ICAM-1) and blocks the activation of T lymphocytes when coimmobilized with anti-CD3. These data demonstrate a general mucin effect on lymphocyte adhesion and activation that is primarily steric in nature and implicates mucins as general barriers to lymphocyte-tumour cell interactions. Mucin blockade of cell-cell interactions may explain why mucinous tumours are often associated with a poor prognosis.  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