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   3463869篇
  免费   296892篇
  国内免费   13949篇
耳鼻咽喉   47486篇
儿科学   109250篇
妇产科学   87957篇
基础医学   551450篇
口腔科学   93328篇
临床医学   313896篇
内科学   614758篇
皮肤病学   89531篇
神经病学   298504篇
特种医学   138435篇
外国民族医学   299篇
外科学   536024篇
综合类   106205篇
现状与发展   24篇
一般理论   2285篇
预防医学   294548篇
眼科学   78933篇
药学   238649篇
  24篇
中国医学   9585篇
肿瘤学   163539篇
  2021年   55314篇
  2020年   35191篇
  2019年   58238篇
  2018年   71577篇
  2017年   54489篇
  2016年   60155篇
  2015年   74269篇
  2014年   108627篇
  2013年   173703篇
  2012年   93526篇
  2011年   93526篇
  2010年   116973篇
  2009年   121311篇
  2008年   80328篇
  2007年   83521篇
  2006年   94052篇
  2005年   89569篇
  2004年   91518篇
  2003年   82425篇
  2002年   71539篇
  2001年   111095篇
  2000年   104704篇
  1999年   102279篇
  1998年   66233篇
  1997年   63831篇
  1996年   62026篇
  1995年   57784篇
  1994年   51796篇
  1993年   48387篇
  1992年   73549篇
  1991年   70261篇
  1990年   66587篇
  1989年   65145篇
  1988年   60425篇
  1987年   59090篇
  1986年   55913篇
  1985年   56004篇
  1984年   50451篇
  1983年   45780篇
  1982年   42554篇
  1981年   39985篇
  1980年   37686篇
  1979年   41777篇
  1978年   36575篇
  1977年   33126篇
  1976年   30464篇
  1975年   29044篇
  1974年   30280篇
  1973年   29046篇
  1972年   27044篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The author describes a concept of automobilisation of the cervical spine and suboccipital joints. The well known biomechanic peculiarities of cervical spine are transformed in a therapeutic setting to allow a form of automobilisation within a closed system of head and underlying base. The so resulting new patterns of movement – the so-called “advanced movement”– differ from those usually exercised. Slow motion moving and low strength efforts are resulting in mobilisation of important vertebral and soft tissue structures.  相似文献   
992.
Prat  F. 《Acta endoscopica》2002,32(2):507-510
Acta Endoscopica - L’hémorragie iatrogène en endoscopie digestive reste pour l’essentiel l’apanage des techniques de résection tumorale et de la...  相似文献   
993.
994.
In standing, there are small sways of the body. Our interest is to use an artificial task to illuminate the mechanisms underlying the sways and to account for changes in their size. Using the ankle musculature, subjects balanced a large inverted pendulum. The equilibrium of the pendulum is unstable and quasi-regular sway was observed like that in quiet standing. By giving full attention to minimising sway subjects could systematically reduce pendulum movement. The pendulum position, the torque generated at each ankle and the soleus and tibialis anterior EMGs were recorded. Explanations about how the human inverted pendulum is balanced usually ignore the fact that balance is maintained over a range of angles and not just at one angle. Any resting equilibrium position of the pendulum is unstable and in practice temporary; movement to a different resting equilibrium position can only be accomplished by a biphasic 'throw and catch' pattern of torque and not by an elastic mechanism. Results showed that balance was achieved by the constant repetition of a neurally generated ballistic-like biphasic pattern of torque which can control both position and sway size. A decomposition technique revealed that there was a substantial contribution to changes in torque from intrinsic mechanical ankle stiffness; however, by itself this was insufficient to maintain balance or to control position. Minimisation of sway size was caused by improvement in the accuracy of the anticipatory torque impulses. We hypothesise that examination of centre of mass and centre of pressure data for quiet standing will duplicate these results.  相似文献   
995.
BACKGROUND: The risk for allergic reactions depends on the sensitivity of individuals and the quantities of offending food ingested. The sensitivity varies among allergic individuals, as does the threshold dose of a food allergen capable of inducing an allergic reaction. OBJECTIVE: This study aimed at determining the distribution of minimum provoking doses of hazelnut in a hazelnut-allergic population. METHODS: Thirty-one patients with a history of hazelnut-related allergic symptoms, a positive skin prick test to hazelnut and/or an elevated specific IgE level, were included. Double-blind, placebo-controlled food challenges (DBPCFC) were performed with seven increasing doses of dried hazelnut (1 mg to 1 g hazelnut protein) randomly interspersed with seven placebo doses. RESULTS: Twenty-nine patients had a positive challenge. Itching of the oral cavity and/or lips was the first symptom in all cases. Additional gastrointestinal symptoms were reported in five patients and difficulty in swallowing in one patient. Lip swelling was observed in two patients, followed by generalized urticaria in one of these. Threshold doses for eliciting subjective reactions varied from a dose of 1 mg up to 100 mg hazelnut protein (equivalent to 6.4-640 mg hazelnut meal). Extrapolation of the dose-response curve showed that 50% of our hazelnut-allergic population will suffer from an allergic reaction after ingestion of 6 mg (95% CI, 2-11 mg) of hazelnut protein. Objective symptoms were observed in two patients after 1 and 1,000 mg, respectively. CONCLUSION: DBPCFCs demonstrated threshold doses in half of the hazelnut-allergic patients similar to doses previously described to be hidden in consumer products. This stresses the need for careful labelling and strategies to prevent and detect contamination of food products with hazelnut residues.  相似文献   
996.
997.
Ten oxacillin-sensitive Staphylococcus aureus strains were grown on agar containing four times their ciprofloxacin MIC to determine if exposure to ciprofloxacin would increase their resistance to oxacillin. All strains grew on the ciprofloxacin-containing agar and subsequently grew on oxacillin-salt agar. The geometric mean MICs for oxacillin increased one- to sixteen-fold and remained elevated after ten passages on antibiotic-free agar. The mecA gene was not detected in any strain. There was no increase in oxacillin MICs when the bacteria were passaged on agar containing four times their MIC of piperacillin/tazobactam. Exposure of oxacillin-sensitive strains of Staphylococcus aureus to ciprofloxacin may increase their MICs to oxacillin. Electronic Publication  相似文献   
998.
E. Soncini  A. Petit   《ITBM》2002,23(3):172
Regulations evolve and risks management becomes one of the biomedical engineers' preoccupations. Thus, risks are various, and consequently it is difficult to identify, to manage and to bring them under control. Furthermore, regulations exist for sectors like healthcare technology monitoring, but it is not the same thing for instance for the risks linked to the maintenance. Thus regulation in the sector of maintenance evolves and the decree of the 1st July law of health safety is going to modify the biomedical environment. The goal of this work is to study the tools and the methods of risks management that have been used for several years in the industrial field and to use them for some biomedical equipment like monitors or IV pumps. These methods adapted to these equipment will allow us to determine some appropriate rules of maintenance.  相似文献   
999.
1000.
Polyploidization and centrosome hyperamplification in inflammatory bronchi   总被引:1,自引:0,他引:1  
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi.  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