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   935613篇
  免费   66520篇
  国内免费   1360篇
耳鼻咽喉   12973篇
儿科学   24424篇
妇产科学   23252篇
基础医学   133347篇
口腔科学   28344篇
临床医学   80781篇
内科学   184218篇
皮肤病学   19336篇
神经病学   72572篇
特种医学   36887篇
外国民族医学   79篇
外科学   152801篇
综合类   18049篇
现状与发展   1篇
一般理论   234篇
预防医学   61855篇
眼科学   21335篇
药学   72769篇
  3篇
中国医学   2171篇
肿瘤学   58062篇
  2018年   9027篇
  2017年   7081篇
  2016年   7831篇
  2015年   8929篇
  2014年   12056篇
  2013年   17612篇
  2012年   24271篇
  2011年   25260篇
  2010年   14930篇
  2009年   14363篇
  2008年   24792篇
  2007年   25914篇
  2006年   26715篇
  2005年   25621篇
  2004年   24759篇
  2003年   23802篇
  2002年   23308篇
  2001年   54847篇
  2000年   56644篇
  1999年   47050篇
  1998年   10767篇
  1997年   9504篇
  1996年   9642篇
  1995年   8970篇
  1994年   8323篇
  1993年   7618篇
  1992年   35538篇
  1991年   33976篇
  1990年   32777篇
  1989年   31925篇
  1988年   29052篇
  1987年   28288篇
  1986年   26322篇
  1985年   25191篇
  1984年   17860篇
  1983年   15168篇
  1982年   7810篇
  1981年   6778篇
  1979年   15802篇
  1978年   10614篇
  1977年   9064篇
  1976年   7887篇
  1975年   8642篇
  1974年   10479篇
  1973年   9874篇
  1972年   9376篇
  1971年   8862篇
  1970年   8442篇
  1969年   7947篇
  1968年   7215篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Based on repeated fluoroangiographic examinations in a group of 28 children with type I diabetes mellitus the authors observed progressing diabetic retinal changes. At the end of the three-year observation period they found progress in 32% of the children. They investigated influence of risk factors such as age, duration of the basic disease, its metabolic compensation, sex and HLA typing on the development of diabetic retinopathy.  相似文献   
992.
The laminar structure and cellular distribution of cytochrome-oxidase (CO) reactivity in supragranular puffs of striate cortex was examined in adult macaque monkeys surviving various periods of monocular enucleation, lid suture, and retinal impulse blockage with tetrodotoxin (TTX). Enucleation and TTX produced a rapid and severe loss in the size of the CO reactive region in puffs dominated by the removed or treated eye compared to slower and less marked reductions obtained in deprived puffs of lid-sutured monkeys. In all deprived animals, the cross-sectional areas of deprived puffs decreased most rapidly in the upper layers (2 and 3A). In long-term enucleated (60 wks) and TTX-treated (4 wks) monkeys, puff area was severely reduced in layer 3B, while reactivity in layer 3B appeared partially spared in lid-sutured monkeys. The density of the CO reaction product was significantly and evenly reduced throughout deprived puffs for all of the monkeys examined; however, this decrease was less severe in adult monkeys lid-sutured for 11 wks. Although no evidence for cell loss was obtained, all three forms of visual deprivation led to lower counts of neuronal perikarya with high levels of CO reaction product in both deprived puff and interpuff areas. This effect was less marked in the deprived puffs of monkeys lid-sutured for 2.5 and 3 yrs, suggesting recovery of CO activity in some neurons. Neurons in deprived puffs and interpuffs were generally similar in size to those in nondeprived regions, although CO-reactive cells were significantly smaller in the deprived puffs of monkeys enucleated for 28.5 or 60 wks. These results indicate that the metabolic response of neuronal elements in supragranular striate cortex depends upon the nature of the visual deficit. The partial sparing of CO reactivity in deprived puffs of lid-sutured monkeys may reflect the continued transmission of certain types of visual stimuli through a closed eyelid.  相似文献   
993.
994.
Immunoblotting of streptococcal antigens in guttate psoriasis   总被引:6,自引:0,他引:6  
Guttate psoriasis may be precipitated by acute streptococcal infection, usually of the upper respiratory tract. We have studied the immune response to streptococci in 26 patients presenting with a first or recurrent episode of acute guttate psoriasis (AGP), using immunoblotting. Eighteen of 26 patients studied had a demonstrable response to a wide range of streptococcal antigens using this approach, compared with 14 of 26 patients who demonstrated a response using more conventional anti-streptococcal antibody tests. Patients with AGP had a significantly higher antibody detection score using immunoblotting than did control subjects (P<0.005). We conclude that immunoblotting is a useful technique in studying this condition and may be of benefit in exploring the immunopathogene-sis of AGP.  相似文献   
995.
Trazodone hydrochloride is an oral antidepressant agent which has been associated with the improvement of erections in impotent men and the development of prolonged erections or priapism in potent men. An in vivo study in animal and human subjects was performed to gain experience with the effect of intracavernosal trazodone. In the anesthetized New Zealand White rabbit, intracavernosal trazodone or its major metabolite m-chlorophenylpiperazine (m-CPP) produced full penile erection in 76% and 84% of animals studied respectively with doses ranging from one to 15 mg. On the other hand, intracavernosal administration of five mg. papaverine resulted in a prolonged erection in 90% of animals studied. In 13 selected volunteer patients, intracavernosal trazodone caused tumescence but not full penile erection with corporal body pressures of 28.2 +/- 5.8 mm. Hg. Intracavernosal papaverine or papaverine and phentolamine in these subjects resulted in significantly higher corporal body pressures of 58 +/- 18 mm. Hg (p less than .05). Intracavernosal administration of alpha adrenoceptor agonists but not normal saline resulted in complete detumescence of trazodone- or m-CPP-induced prolonged erection in the animal studies. Intracavernosal trazodone results in erectile activity that appears in part based on its local alpha blocking activity but like other intracavernosal alpha-blocking agents is not as effective in initiating penile erections as are intracavernosal agents that directly induce smooth muscle relaxation.  相似文献   
996.
On the basis of analysis of surgical treatment of 753 patients with coxarthrosis during 1970-1987, the authors set forth the stages of arthroplasty development in the USSR, using the experience of the Kharkov research institute of orthopaedics and traumatology named after M. I. Sitenko on the problems of arthrodesis operations, endoprosthetics and biological arthroplasty. In the article are presented the peculiar features of diagnostic and surgical tactics in case of patients with idiopathic and dysplastic coxarthrosis; operation technique for each form is presented in details. The authors have developed a new perosseous access to the hip joint, which made a good showing and permits to preserve the integrity of periarticular muscles and neurovascular formations. Application of the given access made possible the extension of indications for arthroplasty in case of grave forms of coxarthrosis, met earlier in a reserved manner.  相似文献   
997.
998.
A 10-month-old child with achondroplasia with progressive head enlargement, ventriculomegaly, and wide subarachnoid spaces over the hemispheres was referred for evaluation. A steady-state lumbar infusion test revealed increased cerebrospinal fluid (CSF) outflow resistance (14 mm Hg/ml/min), and intra-arterial digital subtraction angiography (DSA) demonstrated bilateral venous outflow obstruction due to stenosis of the jugular foramen. Surgical decompression by opening the right jugular foramen relieved the clinical signs of intracranial hypertension. During the following year, the patient's head enlargement was moderate with relative normalization of size. Repeat DSA demonstrated improved venous runoff on the right side, and a steady-state lumbar infusion test demonstrated reduced CSF outflow resistance (10 mm Hg/ml/min). Venous decompression is causal therapy and may prove to be preferable to shunting in children with hydrocephalus and bilateral stenosis of the jugular foramen.  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