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   1069195篇
  免费   80348篇
  国内免费   2797篇
耳鼻咽喉   13495篇
儿科学   36560篇
妇产科学   29829篇
基础医学   155089篇
口腔科学   29247篇
临床医学   98078篇
内科学   208607篇
皮肤病学   23892篇
神经病学   86220篇
特种医学   40704篇
外国民族医学   306篇
外科学   159301篇
综合类   24667篇
一般理论   466篇
预防医学   84455篇
眼科学   24313篇
药学   76676篇
  4篇
中国医学   2104篇
肿瘤学   58327篇
  2019年   8602篇
  2018年   12133篇
  2017年   9430篇
  2016年   10669篇
  2015年   12106篇
  2014年   16702篇
  2013年   25117篇
  2012年   33929篇
  2011年   35867篇
  2010年   21374篇
  2009年   20010篇
  2008年   33487篇
  2007年   35523篇
  2006年   35942篇
  2005年   34338篇
  2004年   33415篇
  2003年   31863篇
  2002年   30775篇
  2001年   47675篇
  2000年   48679篇
  1999年   41057篇
  1998年   12070篇
  1997年   10862篇
  1996年   10843篇
  1995年   10381篇
  1994年   9588篇
  1993年   8971篇
  1992年   32745篇
  1991年   31952篇
  1990年   31427篇
  1989年   30276篇
  1988年   27557篇
  1987年   27677篇
  1986年   25838篇
  1985年   24982篇
  1984年   18799篇
  1983年   15920篇
  1982年   9716篇
  1981年   8765篇
  1979年   17182篇
  1978年   12519篇
  1977年   10556篇
  1976年   9939篇
  1975年   10355篇
  1974年   12496篇
  1973年   12008篇
  1972年   11031篇
  1971年   10250篇
  1970年   9489篇
  1969年   8826篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The short section of the urethra that passes through the urogenital diaphragm is termed the membranous urethra. It is accompanied by several vessels and nerve fibers. In surgery on the membranous urethra the perineal body is of crucial importance, and precise knowledge of the course of the urethra through the pelvic floor is essential. Furthermore, the relationship between the membranous urethra and its accompanying structures is of great importance. These include the branches of the internal pudendal artery, the prostatic venous plexus and the cavernous nerves coursing ventrally from the pelvic plexus. The nerves supplying the membranous urethra were studied in fetuses with the help of a magnifying lens. The results of the dissections are documented by histological sections, photographs and paintings.  相似文献   
992.
Résumé L'utilisation de matériaux d'ostéosynthèse biodégradables a l'avantage d'éviter la réintervention pour extraire le matériel. Les biomatériaux de polymères polyglycolides ont été expérimentés sur plus de 3 600 animaux de laboratoire avant leur introduction en pratique clinique. Depuis 1984 nous les avons utilisés comme matériau d'ostéosynthèse dans près de 1 700 cas parmi lesquels 880 cas de fracture malléolaire, 226 cas d'ostéotomie en chevron pour hallux valgus, 65 cas de fracture de la tête radiale et 54 cas de fracture de l'olécrane. Parmi les 800 premiers cas traités par broches biodégradables nous avons obtenu des résultats favorables et sans incidents dans 91 pour cent des cas. Il y eut 7 cas de fixation défaillante nécessitant une réintervention. Il y a eu 7 cas d'infection superficielle et 3 cas d'infection profonde. Nous avons observé la formation d'une collection séreuse sous-cutanée sans influence sur le résultat radiologique ou clinique dans 52 cas (6,5 %). Au vue de ces résultats et compte tenu des avantages économiques et psychologiques des matériaux biodégradables (pas de réintervention), on peut penser que l'usage de biomatériaux rivalise favorablement avec l'usage de matériaux conventionnels dans certains types d'ostéosynthèse.
Utilization of biodegradable implants in the surgical treatment of fractures and osteotomies
Summary The utilization of biodegradable implants instead of metals in orthopaedic surgery abolishes the need to remove the fixation material. For this study biodegradable rods and screws of self-reinforced polyglycolide, polylactide and lactide-glycolide copolymer were developed and manufactured. The clinical introduction of these implants was preceded by thorough experimental studies with 3 600 animals. From November 1984 the developed biodegradable method of osteofixation was used in 1 700 operations. These included 880 displaced malleolar fractures, 226 chevron-osteotomy for hallux valgus, 65 displaced fracture of the radial head, 54 displaced frature of the olecranon and other fresh fractures or orthopaedic operations. In the first 800 cases operated on using self-reinforced polyglycolide rods the postoperative course was uneventful (91%). Because of failure in the fixation reoperation was needed in 7 cases. A superficial wound infection was observed in 7 cases, deep infection in 3 and transient fluid accumulation in 52 cases (6,5%). Fluid accumulation did not influence the radiological or clinical end-result. The advantages of biodegradable fixation are many-sided. There is a costbenefit and clinical capacity is free for other use, and psychological advantages must be emphasised because removal of implants is not needed. The over all results of this study were considered favourable.
  相似文献   
993.
Study Objective . To determine the efficacy of high-dose ascorbate supplementation in lowering lipoprotein(a) [Lp(a)] levels in patients with premature coronary heart disease (CHD). Design . Randomized, double-blind, placebo-controlled trial. Setting . Outpatient clinic. Patients . Forty-four patients with documented premature CHD. defined as confirmed myocardial infarction and/or angiographically determined stenosis of 50% or greater in at least one major coronary artery before age 60 years. Interventions . Patients were block randomized on the basis of age, gender, and screening Lp(a) concentrations to receive ascorbate 4.5 g/day or placebo for 12 weeks. Measurements and Main Results . High-dose ascorbate was well tolerated and produced a marked elevation in mean plasma ascorbate levels (+1.2 mg/dl; p<0.001). Multiple linear regression analysis revealed no significant effect of supplementation on postintervention Lp(a) levels (p=0.39) in a model that included treatment group assignment, and baseline Lp(a) levels. Conclusions . Our findings do not support a clinically important lowering effect of high-dose ascorbate on plasma Lp(a) in patients with premature CHD.  相似文献   
994.
995.
Tuberculosis and leprosy are chronic bacterial infectious diseases which represent major health problems worldwide. It is generally accepted that, on the one hand, effective vaccination strategies are required for satisfactory control of these diseases and, on the other hand, that currently available vaccination measures are insufficient for this purpose. Ideally, a subunit vaccine should be designed which is composed of one or a few protective antigens. In this brief treatise our approach towards the identification of antigens with potential value for vaccine design is described. It comprises high resolution fractionation by two-dimensional gel electrophoresis, transfer of separated fractions by electroelution and testing of separated fractions with viable T cells and accessory cells. Using this approach we find: (1) multiple antigens are recognized by T cells from leprosy and tuberculosis patients as well as healthy contacts; (2) apparently, suppressive antigens exist in leprosy; (3) an antigen cluster which is apparently indicative for immunity against M. tuberculosis is present among secreted proteins. We hope that further improvement of this methodology will help in the rational design of subunit vaccines against tuberculosis and leprosy.  相似文献   
996.
997.
African Americans are at increased risk for cancer and represent an important target population for programs such as Healthy People 2000, the Cancer Information Service (CIS), and the 5 a Day for Better Health Initiative. Yet, awareness of such programs among rural blacks is unknown. This study assessed awareness of these programs and determined related knowledge and beliefs among rural African Americans. It was undertaken as part of the baseline survey for the Black Churches United for Better Health project, a National Cancer Institute-funded initiative. A minority of respondents (n = 3737) demonstrated name recognition of Healthy People 2000 (23.4%), the CIS (42.4%), and the 5 a Day Program (40.7%). Far fewer (7.4%) were able to correctly identify the recommended daily number of servings of fruits and vegetables. Reported family history of cancer was associated with a greater tendency believe that eating more fruits and vegetables can prevent disease. These findings underscore the need for efforts to reach the rural black community with culturally sensitive and stage appropriate cancer prevention messages. Knowledge of family history of cancer may play an important role in targeting subgroups and delivering effective cancer prevention messages.  相似文献   
998.
999.
1000.
114 patients aged over 75 underwent surgery for aneurysm of the infra-renal abdominal aorta in the University Teaching Hospitals in Nantes and Angers between 1979 and 1988. A retrospective study of these patients was performed to evaluate the immediate and long-term results. The mean age of the patients was 79 (+/- 4) years, the oldest being 94. 70% were men. Half of the patients underwent emergency or semi-emergency surgery (52 cases). Cardiovascular factors (in particular coronary insufficiency in 17% of cases) were the most common risk factors. In all cases grafting after laying open the aneurysm was performed, with an aorto-aortic graft in 32% of patients, an aorto-iliac graft in 37% or an aorto-bifemoral graft in 27% of patients. Combined intestinal revascularisation was performed in 10% of case either involving the inferior mesenteric artery or at least one internal iliac artery; renal revascularisation was performed in 3.5% of cases. 75% of patients underwent simple grafting. The mean duration of hospitalisation was 14 days (+/- 6), including a mean period of 7 days in ICU. 36 patients (31%) died in the first post-operative month. The mortality rate in patients who underwent emergency surgery for a complication of the aneurysm (essentially rupture) was 61% versus 6' for elective surgery. 96% of the patients who survived the first post-operative month were independent at the end of the study or at the time of their death.(ABSTRACT TRUNCATED AT 250 WORDS)  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