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   536395篇
  免费   27943篇
  国内免费   506篇
耳鼻咽喉   6723篇
儿科学   17033篇
妇产科学   12757篇
基础医学   93565篇
口腔科学   12459篇
临床医学   48982篇
内科学   96765篇
皮肤病学   12008篇
神经病学   34805篇
特种医学   20096篇
外国民族医学   54篇
外科学   78772篇
综合类   7650篇
现状与发展   2篇
一般理论   108篇
预防医学   39038篇
眼科学   11995篇
药学   41944篇
  1篇
中国医学   1141篇
肿瘤学   28946篇
  2021年   3987篇
  2018年   5822篇
  2017年   4204篇
  2016年   4971篇
  2015年   5483篇
  2014年   7276篇
  2013年   10698篇
  2012年   15889篇
  2011年   17692篇
  2010年   10144篇
  2009年   8998篇
  2008年   15975篇
  2007年   17715篇
  2006年   17197篇
  2005年   16547篇
  2004年   16128篇
  2003年   15509篇
  2002年   15064篇
  2001年   22622篇
  2000年   23184篇
  1999年   19114篇
  1998年   5305篇
  1997年   4418篇
  1996年   4431篇
  1995年   4175篇
  1992年   14498篇
  1991年   15887篇
  1990年   16039篇
  1989年   15737篇
  1988年   14415篇
  1987年   14280篇
  1986年   13264篇
  1985年   12791篇
  1984年   9459篇
  1983年   8059篇
  1982年   4204篇
  1979年   9016篇
  1978年   6435篇
  1977年   5204篇
  1976年   5549篇
  1975年   6662篇
  1974年   7461篇
  1973年   7224篇
  1972年   6654篇
  1971年   6377篇
  1970年   5942篇
  1969年   5525篇
  1968年   5206篇
  1967年   4657篇
  1966年   3994篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
991.
992.
The objective of this study was to estimate the incidence of hip fracture in the canton of Vaud, Switzerland (total population 584 000), for the period 1986–1991 using routine hospital discharge data collected by the Cantonal Service of Statistical Research and Information (SCRIS). For the survey period, the estimated average annual crude incidence rate of hip fractures was 167 per 100 000 persons aged 20 or older (241 for women and 84 for men). For the population aged 50 years or older, the crude incidence rate was 388 per 100 000 persons (546 for women and 185 for men). The average annual age-specific rates rose exponentially by successive 5-year age groups. The median age of patients at the time of the fracture was 82 years in women and 74 years in men. There was no significant difference between the total number of cervical and trochanteric fractures. Between the ages of 20 and 84 years, the cumulative risk for a woman to be admitted to hospital with a hip fracture was twice that of a man (15.8% vs 7.8%). From 1986 to 1991, the age- and sex-adjusted incidence, like the ratio of cervical to trochanteric fractures, did not show any significant trend, although it was consistent with an increase in men (p=0.09). However, the annual number of fractures rose from 644 to 776, particularly among very aged men. The mean length of stay in the acute care hospital fell from 38 days in 1986 to 25 days in 1991. Finally, the comparison of these results with those obtained in 1986 for the same population from more exhaustive sources has confirmed the provision of a consistent, although overestimated, assessment of hip fracture incidence by means of these routine hospital statistics in the canton of Vaud, Switzerland.  相似文献   
993.
994.
995.
The authors present the results of a transmission electron-microscopic study performed on a tissue sample obtained by an intraocular fine-needle aspiration biopsy in a case of retinoma. The ultrastructural study showed that the tumor was composed mainly of granular osmiophilic material which contained some tumor cells. These cells showed peculiar ultrastructural characteristics, which demonstrated their neural character, and appeared in different degenerative stages. Apparently, this is the first case in whom ultrastructural technique have been applied to study an intraocular tumor sample obtained by intraocular fine-needle aspiration biopsy, and the first case of retinoma studied by such a diagnostic approach.  相似文献   
996.
An eye protection program is needed in occupational medicine policies. Typical eye injuries and eye accidents, as they relate to occupational accidents, justify the management advocating such a program. A recommended model for a functional eye protection program is provided and defined.  相似文献   
997.
Central sensory and motor conduction in vitamin B12 deficiency.   总被引:7,自引:0,他引:7  
Four patients with subacute combined degeneration were studied through upper and lower limb SEPs recorded with a non-cephalic reference montage and through cortical and spinal magnetic stimulation. Clinical signs were confined to the lower limbs in 3 patients; the remaining patient presented only paraesthesiae in 4 limbs. Median nerve SEPs showed a normal cervical N13 response with a significant increase of central conduction time concerning exclusively the P9-P14 interpeak interval. Central motor conduction to upper and lower limb muscles was abnormal. Nerve conduction studies provided no evidence of peripheral nerve involvement. These electrophysiological findings suggest that in vitamin B12 deficiency the higher segments of the cervical cord are usually affected first and that central sensory and motor conduction studies are sensitive methods for detecting such damage.  相似文献   
998.
Disease processes in the peritoneum, omentum, and mesentery occasionally are not recognized at radiologic examination. The authors have used computed tomography (CT) to categorize the radiologic appearances of the more common abnormalities into three basic patterns: (a) solid but relatively well-defined masses, (b) cystic-appearing masses, and (c) ill-defined or infiltrative processes. The most common solid masses to affect these anatomic regions are secondary neoplasms, which are associated with enhancement of the peritoneum on contrast material-enhanced CT scans and, typically, ascites. The various cystic-appearing masses (including cystic lymphangioma, cystic mesothelioma, teratoma, and loculated ascites) and infiltrating masses (such as peritoneal mesothelioma, retractile mesenteritis, desmoid, and carcinoid) must be differentiated on the basis of clinical findings and additional imaging findings (eg, CT depiction of fat and calcium in teratomas and the radiating appearance of carcinoids). Although the CT appearances of some of the abnormalities overlap, classifying them by pattern is helpful in narrowing the range of the differential diagnosis.  相似文献   
999.
We describe the types of aggressive behaviour and determine their prevalence in a sample of hospitalized elderly psychiatric patients. Data were obtained by nurse ratings of aggressive behaviour using the recently developed Rating Scale for Aggressive Behaviour in the Elderly; 90 patients were rated over a 3-d period. Nearly half the sample were at least mildly aggressive; the frequencies of some specific types of aggressive behaviour were high. In contrast, the frequency of injuries and the use of restraints and medication for aggressive behaviour were low. Some correlates of the aggressive behaviour were also analysed.  相似文献   
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