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   1344140篇
  免费   94666篇
  国内免费   2956篇
耳鼻咽喉   19823篇
儿科学   40334篇
妇产科学   38737篇
基础医学   188290篇
口腔科学   40011篇
临床医学   113148篇
内科学   264299篇
皮肤病学   30369篇
神经病学   107025篇
特种医学   53980篇
外国民族医学   435篇
外科学   209800篇
综合类   31072篇
现状与发展   6篇
一般理论   437篇
预防医学   92340篇
眼科学   31509篇
药学   100701篇
  4篇
中国医学   3026篇
肿瘤学   76416篇
  2018年   11891篇
  2015年   12016篇
  2014年   16872篇
  2013年   25544篇
  2012年   33364篇
  2011年   35308篇
  2010年   20963篇
  2009年   20467篇
  2008年   33913篇
  2007年   37097篇
  2006年   37639篇
  2005年   36396篇
  2004年   35462篇
  2003年   34435篇
  2002年   33977篇
  2001年   63818篇
  2000年   65527篇
  1999年   55603篇
  1998年   14762篇
  1997年   13561篇
  1996年   13019篇
  1995年   12283篇
  1994年   11531篇
  1992年   42939篇
  1991年   41444篇
  1990年   40722篇
  1989年   39708篇
  1988年   37134篇
  1987年   36572篇
  1986年   35032篇
  1985年   33202篇
  1984年   24895篇
  1983年   21127篇
  1982年   12690篇
  1981年   11600篇
  1980年   10796篇
  1979年   23993篇
  1978年   17102篇
  1977年   14867篇
  1976年   13423篇
  1975年   15289篇
  1974年   18114篇
  1973年   17597篇
  1972年   16855篇
  1971年   15754篇
  1970年   14952篇
  1969年   14378篇
  1968年   13494篇
  1967年   12039篇
  1966年   11280篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
The enormous development in the field of molecular genetics during the last decades has lead to optimism concerning the possibilities for identifying the causes of multiple sclerosis (MS) through genetic studies. However, we have learned that dense mapping of large sample sets is needed, which only can be achieved through large collaborative studies. The contribution from each yet unidentified gene is probably weaker than that of the well established human leukocyte antigen association. The ultimate goal of the search for susceptibility genes in MS is to develop diagnostic tools and better treatments that can prevent or reduce the development of symptoms of this often devastating disease.  相似文献   
993.
OBJECTIVE: The objective of this study was to determine if temporomandibular joint (TMJ) samples positive for Chlamydia trachomatis have a greater presence of tumor necrosis factor-alpha (TNFalpha) or interleukin-6 (IL-6) when compared with Chlamydia-negative samples. STUDY DESIGN: Posterior bilaminar tissue samples removed during TMJ surgery from 70 patients were evaluated. Cryosections were stained using monoclonal antibody that identifies C. trachomatis. The presence of IL-6 and TNFalpha were evaluated by immunostaining in 15 samples positive and in 25 samples negative for the presence of C. trachomatis. RESULTS: Of the 70 TMJ samples, 32 (46%) were positive for C. trachomatis. In 15 samples positive for C. trachomatis, 10 (67%) were positive for TNFalpha and 7 (47%) for IL-6. In 25 samples negative for C. trachomatis, only 4 (16%) were positive for TNFalpha and only 2 (8%) for IL-6. Differences in C. trachomatis-positive samples versus negative were significant for both TNFalpha (P < .002) and IL-6 (P < .008). CONCLUSION: The presence of C. trachomatis in the TMJ is associated with a significantly increased presence of TNFalpha and IL-6.  相似文献   
994.
Tendon injuries of the hand, especially flexor tendon injuries, should be treated by specially trained surgeons. Tendon injuries should be treated immediately to avoid joint stiffness or tendon adhesions, which arise predominantly at the tendon laceration. In addition to a professional operation, postoperative management is also important. As with surgery, specially trained physiotherapists should supervise the active or passive mobilization after tendon repair. A close cooperation between physiotherapist and physician is mandatory for an optimal result.  相似文献   
995.
Isolated fractures of the metacarpal and phalangeal bones are common injuries of the upper extremities. They usually occur at the age of 10–40, whereas the highest incidence is observed in childhood. The results of treatment have an important impact for the practical value of the hand. This article aims to give a brief overview of the different fracture types and their treatment options.  相似文献   
996.
Objective To describe the clinical presentation of acute diverticulitis in an emergency department and to characterize the natural history of diverticulitis in the short perspective. Comparisons are made with an important differential diagnosis, nonspecific abdominal pain (NSAP). Method Patients admitted to our hospital with abdominal pain of up to 7 days’ duration were registered prospectively using a detailed schedule for history, symptoms and signs, from 1 February 1997 to 1 June 2000. Of 3349 patients initially included, 3073 (92%) were eligible for follow up after 1–3 years. Results Acute diverticulitis was the final diagnosis in 145 patients and NSAP in 1142 patients. The incidence of hospitalized patients with diverticulitis was 47 per year and 100 000 population, with a mean hospital stay of 3.3 days. Patients with diverticulitis, more frequently than NSAP, had a longer history and laboratory signs of inflammatory activity. Isolated left abdominal tenderness was more common in diverticulitis, whereas isolated right abdominal tenderness was more common in NSAP. Duration of symptoms on arrival was independent of age and was not correlated to C‐reactive protein, leucocytes or body temperature. Sensitivity of diverticulitis as primary diagnosis was 64% and specificity 97%. Corresponding figures for NSAP were 43% and 90% respectively. Age and gender did not influence diagnostic accuracy or risk of surgery. Conclusion Diverticulitis differs significantly from NSAP in clinical presentation and laboratory parameters. Sensitivity of primary diagnosis for diverticulitis and NSAP was low.  相似文献   
997.
The immunologic risk associated with donor-specific antibodies (DSA) against Class II human leukocyte antigens (HLA) in kidney transplant (KTx) recipients is unclear. The aim of this study was to determine the outcome of KTx when DSA was detected only against HLA Class II. To isolate the impact of anti-Class II DSA, we retrospectively analyzed 12 KTx recipients who at baseline had a positive B-cell flow cytometric crossmatch (FXM) and a negative T-cell FXM. Using alloantibody specification analysis, 58.3% (7/12) had DSA against donor Class II and 41.7% had no demonstrable DSA. Biopsy-proven AMR occurred in 57% (4/7) in the Class II(+) group and 0% in the Class II(-) group (p > 0.05). Peritubular capillaries stained positive for C4d in 86% (6/7) of the Class II(+) patients and in 40% (2/5) of the Class II(-) patients (p > 0.05). One patient in the Class II(+) group lost their graft at 3 months to accelerated transplant glomerulopathy, while all other grafts were functioning 3-37 months posttransplant despite the persistence of anti-Class II DSA. We conclude that KTx recipients with clearly defined anti-Class II DSA are at risk for humoral rejection suggesting that desensitization and/or close posttransplant monitoring may be needed to prevent AMR.  相似文献   
998.
Haemoglobin (Hb) abnormalities in chronic obstructive pulmonary disease (COPD) are not well characterised. The present authors investigated the prevalence and association of abnormal Hb with clinical outcomes. Analysis of a prospective cohort of stable COPD outpatients (n = 683) in a USA Veterans Administration pulmonary clinic was undertaken. Patients were classified as anaemic (Hb <13 g.dL(-1)), polycythemic (Hb > or =17 g.dL(-1) and > or =15 g.dL(-1) for males and females, respectively) or normal. Demographic characteristics and physiological/functional outcomes were compared between groups. Regression models adjusting for confounders examined the independent association of anaemia with clinical outcomes. Anaemia was present in 116 (17%) patients and polycythemia in 40 (6%). While the only values that differed between polycythemic and nonpolycythemic patients were mean body mass index and Hb, anaemic patients showed a significantly higher modified Medical Research Council dyspnoea scale score (2.8 versus 2.6), lower 6-min walk distance (265 versus 325 m) and shorter median survival (49 versus 74 months) than nonanaemic patients. In regression models, anaemia independently predicted dyspnoea and reduced exercise capacity. Anaemia in chronic obstructive pulmonary disease was an independent risk factor for reduced functional capacity. Polycythemia prevalence was low and had no association with worsened outcomes. Further work is required to evaluate the effect of anaemia correction on outcomes in chronic obstructive pulmonary disease.  相似文献   
999.
1000.
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