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   1623289篇
  免费   132656篇
  国内免费   2695篇
耳鼻咽喉   21953篇
儿科学   53262篇
妇产科学   46665篇
基础医学   230536篇
口腔科学   47751篇
临床医学   142516篇
内科学   320782篇
皮肤病学   34312篇
神经病学   131730篇
特种医学   65327篇
外国民族医学   474篇
外科学   247522篇
综合类   39819篇
现状与发展   3篇
一般理论   545篇
预防医学   123501篇
眼科学   36803篇
药学   122729篇
  3篇
中国医学   3016篇
肿瘤学   89391篇
  2018年   15127篇
  2016年   13235篇
  2015年   15362篇
  2014年   21123篇
  2013年   31960篇
  2012年   43468篇
  2011年   45759篇
  2010年   26885篇
  2009年   25798篇
  2008年   43965篇
  2007年   46265篇
  2006年   47031篇
  2005年   45586篇
  2004年   45009篇
  2003年   43092篇
  2002年   42231篇
  2001年   76447篇
  2000年   79129篇
  1999年   67104篇
  1998年   18007篇
  1997年   16537篇
  1996年   16497篇
  1995年   16182篇
  1994年   15217篇
  1993年   14346篇
  1992年   55973篇
  1991年   54346篇
  1990年   53056篇
  1989年   51317篇
  1988年   47687篇
  1987年   47015篇
  1986年   44667篇
  1985年   43221篇
  1984年   32309篇
  1983年   27780篇
  1982年   16236篇
  1981年   14514篇
  1980年   13651篇
  1979年   30669篇
  1978年   21178篇
  1977年   17890篇
  1976年   16774篇
  1975年   17663篇
  1974年   21600篇
  1973年   20781篇
  1972年   18983篇
  1971年   17884篇
  1970年   16395篇
  1969年   15391篇
  1968年   14051篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
OBJECTIVE: To evaluate the prenatal distribution, associated conditions and outcome of the different types of right aortic arch (RAA) detected in fetal life. METHODS: This was a retrospective review of all cases of RAA detected prenatally between 1998 and 2005 in two tertiary referral centers. RESULTS: In the study period 71 cases of RAA were detected; 26 (37%) had RAA with aberrant left subclavian artery, 23 (32%) had RAA with mirror-image branching, 20 (28%) had RAA of unknown type and two (3%) had double aortic arch. While 20/26 cases with RAA and aberrant left subclavian artery were isolated findings, all 23 cases with RAA and mirror-image branching were associated with cardiac defects, namely tetralogy of Fallot (43%) or pulmonary atresia with ventricular septal defect (22%). Of the 20 cases with RAA, 19 of unknown type were associated with heterotaxy syndromes and had additional cardiac malformations and ambiguities of the situs. The two cases with DAA were isolated findings. Seven cases in our series (10%) had a microdeletion 22q11 and these were significantly associated with extracardiac malformations. The outcome in our series depended solely on the associated cardiac and extracardiac malformations, with the exception of one infant with isolated DAA, in whom a surgical correction was warranted. CONCLUSIONS: RAA detected in fetal life is associated frequently with other cardiac/non-cardiac malformations, heterotaxy syndromes and microdeletions 22q11. The associated conditions vary depending on the branching type of the brachiocephalic vessels and the presence of extracardiac malformations.  相似文献   
52.
53.
BACKGROUND CONTEXT: Substantial variation exists regarding the use of sedation before interventional spine techniques. Patient preference should play an important role in decision making regarding the need for sedation. However, little is known about patients' anxiety levels before spinal injections and their perceptions about the necessity of sedation. PURPOSE: To determine patient perception for need for sedation before epidural steroid injections and zygapophyseal joint injections. STUDY DESIGN/SETTING: Survey of consecutive spinal injection patients in an outpatient spine center. PATIENT SAMPLE: 500 consecutive lumbar, thoracic, and cervical patients receiving spinal injections. OUTCOME MEASURES: A 12-item questionnaire assessing patients' perceived anxiety before to a spinal injection. METHODS: Subjects were given the questionnaire after their spinal injection. Percentages requesting sedation for a first and potential second procedure were assessed. Additionally, anxiety level and pain rating, location of injection, age, sex, and other medication use were analyzed to determine the effect on the request for sedation. RESULTS: 17% of patients questioned requested sedation before an injection, and 28% would request sedation if they were to have a second injection. CONCLUSIONS: Routine sedation before diagnostic and therapeutic injections is not necessary as the majority of patients would not request sedation before the procedure when given the option. However, in some patients sedation is indicated, and all patients would benefit from educational material on sedation before the injection.  相似文献   
54.
55.
INTRODUCTION: Autoimmune hepatitis (AIH) is a well-defined entity in the West but there are sparse Indian data on this disease. AIM: To study the clinical profile and response to treatment of Indian patients with AIH. METHODS: This is a part retrospective and part prospective study of 50 patients (median age 48 years, range 11-82; 43 women) seen between 1995 to 2001, diagnosed to have AIH as per the revised scoring system. Clinical and laboratory profile, response to treatment, and complications of treatment were analyzed. RESULTS: AIH accounted for 6% of all patients with liver disease seen during the period. The presenting symptoms were gastrointestinal in 43 and non-gastrointestinal in 7, with median symptom duration of 6 months (range 2 weeks to 40 years). Forty patients (80%) had chronic liver disease. Associated illnesses were present in 28 patients. Twenty-six patients were classified as definite and the rest as probable AIH. Forty-nine patients had Type 1 AIH. Five patients had overlap syndrome. Forty-five patients (90%) received immunosuppressive therapy. Twelve of 18 patients receiving only prednisolone and 21 of 27 patients receiving prednisolone and azathioprine combination responded. Thirteen (26%) patients had therapy-related complications (infectious 5, non infectious 8) with two treatment-related deaths. CONCLUSION: Type 1 AIH was the predominant type of AIH. The majority of patients with AIH presented with chronic liver disease. There was good response to immunosuppressive therapy. Therapy-related complications occurred in one-fourth of patients.  相似文献   
56.
The aim of the present study was to explore differences in the clinical expression, clinical diagnoses and management of airway diseases in a primary-care setting. Patients aged >or=35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females. Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively). In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.  相似文献   
57.
58.
59.
60.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  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