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   30836篇
  免费   2374篇
  国内免费   89篇
耳鼻咽喉   368篇
儿科学   920篇
妇产科学   747篇
基础医学   4044篇
口腔科学   459篇
临床医学   3073篇
内科学   6510篇
皮肤病学   426篇
神经病学   2867篇
特种医学   1245篇
外科学   5282篇
综合类   343篇
现状与发展   1篇
一般理论   52篇
预防医学   2376篇
眼科学   520篇
药学   1574篇
中国医学   46篇
肿瘤学   2446篇
  2023年   294篇
  2022年   450篇
  2021年   1322篇
  2020年   709篇
  2019年   1031篇
  2018年   1237篇
  2017年   845篇
  2016年   837篇
  2015年   999篇
  2014年   1375篇
  2013年   1715篇
  2012年   2508篇
  2011年   2434篇
  2010年   1337篇
  2009年   1060篇
  2008年   1656篇
  2007年   1733篇
  2006年   1521篇
  2005年   1385篇
  2004年   1212篇
  2003年   1034篇
  2002年   876篇
  2001年   291篇
  2000年   264篇
  1999年   265篇
  1998年   196篇
  1997年   162篇
  1996年   176篇
  1995年   155篇
  1994年   123篇
  1993年   114篇
  1992年   236篇
  1991年   225篇
  1990年   229篇
  1989年   212篇
  1988年   195篇
  1987年   208篇
  1986年   156篇
  1985年   198篇
  1984年   175篇
  1983年   156篇
  1982年   139篇
  1981年   121篇
  1980年   116篇
  1979年   167篇
  1978年   138篇
  1977年   80篇
  1974年   74篇
  1972年   76篇
  1970年   74篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
94.
Conclusion  The ACCF/ASNC AC for SPECT MPI provides recommendations for the appropriate use of SPECT MPI. After the publication of the AC document in 2005, the AC has been used by nuclear cardiology practices with many clinical studies evaluating the list of indications in routine clinical practice. From these data. ASNC recommends minor but important changes to the indication list, suggesting the addition of 6 new indications and the modification of the definitions for “chest pain syndrome” and “CHD high risk.”. An objective review of existing indications focused on only those indications that had significant variability among the reviewers (n=20). These indications were reviewed in the presence of existing and new evidence-based data, and ASNC recommends that the grades for 6 indications be re-evaluated. The AC for SPECT MPI will require periodic review as new evidence becomes available or as clinical practice evolves. ASNC recognizes the importance of these criteria to improve the quality of patient care, and it will continue to play a key role in assembling the information for this ongoing review. From the current summary of evidence, ASNC consensus opinions, and ASNC recommendations in this document, ASNC strongly recommends that the AC guidelines be reviewed Prepared by the American Society of Nuclear Cardiology Quality Assurance Subcommittee for Quality in Imaging Standards. Reviewed by members of the American Society of Nuclear Cardiology Quality Assurance Committee. Approved by the American Society of Nuclear Cardiology Board of Directors, September 6, 20.  相似文献   
95.
96.
Neural stem cell (NSC) transplantation has been shown to attenuate the severity of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Central to the future success of NSC transplantation in MS is the ability of transplanted cells to migrate from the site of transplantation to relevant foci of disease. Using magnetically labeled mouse neurospheres and human embryonic stem cell (hESC)-derived neurospheres, we applied serial magnetic resonance imaging (MRI) to assess the biodynamics of transplanted cell migration in a chronic mouse EAE model. Magnetic labeling did not affect the in vitro and in vivo characteristics of cells as multipotential precursors. Cell migration occurred along white matter (WM) tracts (especially the corpus callosum (CC), fimbria, and internal capsule), predominantly early in the acute phase of disease, and in an asymmetric manner. The distance of cell migration correlated well with clinical severity of disease and the number of microglia in the WM tracts, supporting the notion that inflammatory signals promote transplanted cell migration. This study shows for the first time that hESC-derived neural precursors also respond to tissue signals in an MS model, similarly to rodent cells. The results are directly relevant for designing and optimizing cell therapies for MS, and achieving a better understanding of in vivo cell dynamics and cell-tissue interactions.  相似文献   
97.
Quantitative software for the analysis and review of myocardial perfusion emission computed tomography images is an indispensable tool in the nuclear physician's evaluation of patients with known or suspected heart disease. The Corridor4DM (4DM) application (formerly known as 4DM-SPECT), developed at the University of Michigan Medical Center, is a quantitative software application providing automated processing, analysis, and reporting of myocardial perfusion and function from cardiac emission computed tomography studies in a tightly integrated, user-centered environment. With health care placing increased emphasis on higher quality and efficiency in diagnostic imaging, quantitative analysis and review software applications need to provide a comprehensive environment supporting correlative review of multimodality images, integrated report generation, and remote review capabilities. The current and future design capabilities of the 4DM software application are discussed with respect to the changing landscape of imaging, where cardiac computed tomography, positron emission tomography, structured reporting, and remote review are expanding the base requirement specifications for quantitative software.  相似文献   
98.
99.
Use of antibiotic and analgesic drugs during lactation.   总被引:2,自引:0,他引:2  
During lactation, multiple situations can arise that require maternal pharmacological treatment. Because of the many health advantages of human milk to infants, breast feeding should be interrupted only when the needed drug might be harmful to the nursing child and exposure via the breast milk will be sufficient to pose a risk. Since the majority of drugs have not been shown to cause adverse effects when used during lactation, and even temporary interruption of breast feeding can be difficult for the nursing dyad, decisions regarding maternal medication use during breast feeding should be based on accurate and up-to-date information. This article reviews available data on the most commonly used antibiotics and analgesics. The use of most antibiotics is considered compatible with breast feeding. Penicillins, aminopenicillins, clavulanic acid, cephalosporins, macrolides and metronidazole at dosages at the low end of the recommended dosage range are considered appropriate for use for lactating women. Fluoroquinolones should not be administered as first-line treatment, but if they are indicated, breast feeding should not be interrupted because the risk of adverse effects is low and the risks are justified. Paracetamol (acetaminophen), low-dose aspirin (acetylsalicylic acid) [up to 100 mg/day] and short-term treatment with NSAIDs, codeine, morphine and propoxyphene are considered compatible with breast feeding. Safer alternatives should be considered instead of dipyrone, aspirin at a dosage >100 mg/day and pethidine (meperidine). In the light of the many safe alternatives for pain control, breast-feeding mothers should not be allowed to experience pain or be made to feel that they must choose between analgesia and breast feeding.  相似文献   
100.
PURPOSE: Bone marrow transplantation (BMT) is often associated with profound neutropenia. Allogeneic transplant recipients also have defects in both humoral and cellular immunity and thus are subject to increased risk of serious, often life-threatening, infection even beyond the period of granulocyte recovery. The current study was undertaken to evaluate patients who required operative intervention for perianal sepsis following BMT. METHODS: The bone marrow transplant database at a single institution was used to identify all patients diagnosed with perianal infections after autologous or allogeneic BMT. Charts were reviewed in a retrospective manner. RESULTS: Over a ten-year period ending in November 1993, 963 BMT were performed at the City of Hope National Medical Center. Twenty-four patients were diagnosed with perianal infections foEowing their transplants. Fifteen patients did not have purulent collections requiring drainage and were treated with antibiotics and supportive measures alone. Nine patients (37.5 percent) required surgical intervention between 10 and 380 days following transplantation. At the time of surgical intervention, seven patients had purulent collections and two patients had acute and chronic inflammation, tissue necrosis, and fibrosis. Of the two patients with an absolute neutrophil count less than 1,000, a purulent collection was found in one of the patients. Cultures taken from perianal abscesses were almost all polymicrobial, and the most common organisms were Escherichia coli, Bacteroides, Enterococcus,and Klebsiella.For those patients undergoing surgical intervention, mean time to complete wound closure by secondary intention was 37.6 days; five patients healed in less than 15 days, two patients healed at 93 and 114 days, and two patients had persistent, open wounds at time of death, which was unrelated to their perianal disease. Five patients were receiving systemic steroids at time of surgical intervention; this did not appear to affect time to wound healing. CONCLUSIONS: Perianal infections are a rare complication of BMT. Majority of these infections are polymicrobial, and organisms isolated are similar to those seen in the perianal infections of nonimmunosuppressed patients. Despite steroid use, granulocytopenia does not exclude the possible presence of purulent collections, and clinical examination should guide the decision for surgical drainage. In general, perianal wound healing is not prolonged in BMT patients.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Montreal, Quebec, Canada, May 7 to 12, 1995.  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