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   813篇
  免费   58篇
  国内免费   15篇
耳鼻咽喉   1篇
儿科学   19篇
妇产科学   7篇
基础医学   107篇
口腔科学   12篇
临床医学   138篇
内科学   144篇
皮肤病学   10篇
神经病学   49篇
特种医学   133篇
外科学   70篇
综合类   5篇
预防医学   61篇
眼科学   7篇
药学   71篇
中国医学   2篇
肿瘤学   50篇
  2023年   3篇
  2021年   14篇
  2020年   7篇
  2019年   7篇
  2018年   10篇
  2017年   10篇
  2016年   7篇
  2015年   13篇
  2014年   12篇
  2013年   16篇
  2012年   26篇
  2011年   26篇
  2010年   16篇
  2009年   7篇
  2008年   18篇
  2007年   28篇
  2006年   28篇
  2005年   28篇
  2004年   28篇
  2003年   21篇
  2002年   26篇
  2001年   32篇
  2000年   28篇
  1999年   21篇
  1998年   37篇
  1997年   26篇
  1996年   21篇
  1995年   21篇
  1994年   19篇
  1993年   13篇
  1992年   26篇
  1991年   18篇
  1990年   23篇
  1989年   30篇
  1988年   44篇
  1987年   27篇
  1986年   18篇
  1985年   13篇
  1984年   13篇
  1983年   12篇
  1982年   15篇
  1981年   10篇
  1980年   12篇
  1979年   10篇
  1978年   10篇
  1977年   8篇
  1976年   8篇
  1975年   7篇
  1973年   2篇
  1967年   2篇
排序方式: 共有886条查询结果,搜索用时 15 毫秒
71.
During this time of nursing shortages, hospitals that want to maintain the competitive edge must seek ways to recruit and retain a competent nursing staff. This study was conducted in a large hospital that strives to be the primary health care provider and employer of choice in its geographic region. The purpose of the study was to assess new nurses' perceptions of nursing practice and their expectations for meeting professional goals. Sixty-seven new nurses from 13 hospital departments were interviewed. Comprehensive orientation, continuing education, and mentoring were important values identified by this group of nurses. Communication with physicians and fear of causing accidental harm to patients were expressed concerns. Data from this survey will be used by the organization to change orientation policies to better meet the needs of the nursing staff and improve recruitment and retention of nurses.  相似文献   
72.
73.
Reported here are studies of Fanconi anemia fetal cells that led to the first use of umbilical cord blood for hematopoietic reconstitution in a clinical trial. Prenatal diagnosis and HLA typing were performed in fetuses at risk for Fanconi anemia (FA) to identify, prior to birth, those that were unaffected with the syndrome and were HLA-identical to affected siblings. Umbilical cord blood was harvested at the delivery of these infants; assays of progenitor cells indicated the presence of colony-forming units-granulocyte-macrophage (CFU-GM) in numbers similar to those of bone marrow CFU-GM that are associated with successful engraftment in HLA-matched allogeneic bone marrow transplantation. The possibility that umbilical cord blood from a single individual can be used as an alternative to bone marrow for hematopoietic reconstitution has now been demonstrated by the successful engraftment of two patients with FA. Progenitor cell assays of umbilical cord blood collected at the birth of a child affected with FA, who had been misdiagnosed on the basis of chorionic villus sampling (CVS) studies, indicated a profound deficiency in colony formation, consistent with previously reported abnormalities in the growth of FA cells in vitro. These results suggest that the hematopoietic disorder in FA is related to an underlying problem with cell proliferation.  相似文献   
74.
75.
Ellen C. Caniglia  James M. Robins  Lauren E. Cain  Caroline Sabin  Roger Logan  Sophie Abgrall  Michael J. Mugavero  Sonia Hernández-Díaz  Laurence Meyer  Remonie Seng  Daniel R. Drozd  George R. Seage III  Fabrice Bonnet  Fabien Le Marec  Richard D. Moore  Peter Reiss  Ard van Sighem  William C. Mathews  Inma Jarrín  Belén Alejos  Steven G. Deeks  Roberto Muga  Stephen L. Boswell  Elena Ferrer  Joseph J. Eron  John Gill  Antonio Pacheco  Beatriz Grinsztejn  Sonia Napravnik  Sophie Jose  Andrew Phillips  Amy Justice  Janet Tate  Heiner C. Bucher  Matthias Egger  Hansjakob Furrer  Jose M. Miro  Jordi Casabona  Kholoud Porter  Giota Touloumi  Heidi Crane  Dominique Costagliola  Michael Saag  Miguel A. Hernán 《Statistics in medicine》2019,38(13):2428-2446
Decisions about when to start or switch a therapy often depend on the frequency with which individuals are monitored or tested. For example, the optimal time to switch antiretroviral therapy depends on the frequency with which HIV-positive individuals have HIV RNA measured. This paper describes an approach to use observational data for the comparison of joint monitoring and treatment strategies and applies the method to a clinically relevant question in HIV research: when can monitoring frequency be decreased and when should individuals switch from a first-line treatment regimen to a new regimen? We outline the target trial that would compare the dynamic strategies of interest and then describe how to emulate it using data from HIV-positive individuals included in the HIV-CAUSAL Collaboration and the Centers for AIDS Research Network of Integrated Clinical Systems. When, as in our example, few individuals follow the dynamic strategies of interest over long periods of follow-up, we describe how to leverage an additional assumption: no direct effect of monitoring on the outcome of interest. We compare our results with and without the “no direct effect” assumption. We found little differences on survival and AIDS-free survival between strategies where monitoring frequency was decreased at a CD4 threshold of 350 cells/μl compared with 500 cells/μl and where treatment was switched at an HIV-RNA threshold of 1000 copies/ml compared with 200 copies/ml. The “no direct effect” assumption resulted in efficiency improvements for the risk difference estimates ranging from an 7- to 53-fold increase in the effective sample size.  相似文献   
76.
Monoclonal antibodies are increasingly being developed to treat multiple disease areas, including those related to oncology, immunology, neurology, and ophthalmology. There are multiple factors, such as charge, size, neonatal Fc receptor (FcRn) binding affinity, target affinity and biology, immunoglobulin G (IgG) subclass, degree and type of glycosylation, injection route, and injection site, that could affect the pharmacokinetics (PK) of these large macromolecular therapeutics, which in turn could have ramifications on their efficacy and safety. This minireview examines how characteristics of the antibodies could be altered to change their PK profiles. For example, it was observed that a net charge modification of at least a 1-unit shift in isoelectric point altered antibody clearance. Antibodies with enhanced affinity for FcRn at pH 6.0 display longer serum half-lives and slower clearances than wild type. Antibody fragments have different clearance rates and tissue distribution profiles than full length antibodies. Fc glycosylation is perceived to have a minimal effect on PK while that of terminal high mannose remains unclear. More investigation is warranted to determine if injection route and/or site impacts PK. Nonetheless, a better understanding of the effects of all these variations may allow for the better design of antibody therapeutics.  相似文献   
77.
CD4(+) T cells expressing the latent form of transforming growth factor-β [latency-associated peptide (LAP) (TGF-β(1))] play an important role in the modulation of immune responses. Here, we identified a novel peptide ligand (GPC(81-95) ) with an intrinsic ability to induce membrane-bound LAP (TGF-β(1)) expression on a subpopulation of human CD4(+) T cells (using flow cytometry; ranging from 0·8% to 2·6%) and stimulate peripheral blood mononuclear cells to release LAP (TGF-β(1) ) (using ELISPOT assay; ranging from 0·03% to 0·16%). In spite of this low percentage of responding cells, GPC(81-95) significantly reduced Toll-like receptor 4 ligand-induced tumour necrosis factor-α production in a TGF-β(1) - and CD4(+) T-cell-dependent manner. The results demonstrate that GPC(81-95) is a useful tool to study the functional properties of a subpopulation of LAP (TGF-β(1))(+) CD4(+) T cells and suggest a pathway that can be exploited to suppress inflammatory response.  相似文献   
78.
We show constitutive activation of Rho kinase (ROCK) in cells bearing oncogenic forms of KIT, FLT3, and BCR-ABL, which is dependent on PI3K and Rho GTPase. Genetic or pharmacologic inhibition of ROCK in oncogene-bearing cells impaired their growth as well as the growth of acute myeloid leukemia patient-derived blasts and prolonged the life span of mice bearing myeloproliferative disease. Downstream from ROCK, rapid dephosphorylation or loss of expression of myosin light chain resulted in enhanced apoptosis, reduced growth, and loss of actin polymerization in oncogene-bearing cells leading to significantly prolonged life span of leukemic mice. In summary we describe a pathway involving PI3K/Rho/ROCK/MLC that may contribute to myeloproliferative disease and/or acute myeloid leukemia in humans.  相似文献   
79.
80.
Study Design: Comparative assessment of randomized controlled trials of caudal and lumbar interlaminar epidural injections in chronic lumbar discogenic pain.Objective: To assess the comparative efficacy of caudal and lumbar interlaminar approaches of epidural injections in managing axial or discogenic low back pain.Summary of Background Data: Epidural injections are commonly performed utilizing either a caudal or lumbar interlaminar approach to treat chronic lumbar axial or discogenic pain, which is pain exclusive of that associated with a herniated intervertebral disc, or that is due to degeneration of the zygapophyseal joints, or due to dysfunction of the sacroiliac joints, respectively. The literature on the efficacy of epidural injections in managing chronic axial lumbar pain of presumed discogenic origin is limited.Methods: The present analysis is based on 2 randomized controlled trials of chronic axial low back pain not caused by disc herniation, radiculitis, or facet joint pain, utilizing either a caudal or lumbar interlaminar approach, with a total of 240 patients studied, and a 24-month follow-up. Patients were assigned to receive either local anesthetic only or local anesthetic with a steroid in each 60 patient group.Results: The primary outcome measure was significant improvement, defined as pain relief and functional status improvement of at least 50% from baseline, which was reported at 24-month follow-ups in 72% who received local anesthetic only with a lumbar interlaminar approach and 54% who received local anesthetic only with a caudal approach. In patients receiving local anesthetic with a steroid, the response rate was 67% for those who had a lumbar interlaminar approach and 68% for those who had a caudal approach at 12 months. The response was significantly better in the lumbar interlaminar group who received local anesthetic only, 77% versus 56% at 12 months and 72% versus 54% at 24 months.Conclusion: This assessment shows that in patients with axial or discogenic pain in the lumbar spine after excluding facet joint and SI Joint pain, epidural injections of local anesthetic by the caudal or lumbar interlaminar approach may be effective in managing chronic low back pain with a potential superiority for a lumbar interlaminar approach over a caudal approach.  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