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   20118篇
  免费   2084篇
  国内免费   35篇
耳鼻咽喉   126篇
儿科学   667篇
妇产科学   741篇
基础医学   2986篇
口腔科学   535篇
临床医学   2384篇
内科学   4014篇
皮肤病学   303篇
神经病学   1827篇
特种医学   588篇
外科学   2500篇
综合类   500篇
一般理论   17篇
预防医学   2066篇
眼科学   221篇
药学   1709篇
中国医学   32篇
肿瘤学   1021篇
  2021年   233篇
  2020年   159篇
  2019年   259篇
  2018年   306篇
  2017年   207篇
  2016年   250篇
  2015年   308篇
  2014年   408篇
  2013年   626篇
  2012年   905篇
  2011年   937篇
  2010年   539篇
  2009年   518篇
  2008年   805篇
  2007年   967篇
  2006年   890篇
  2005年   777篇
  2004年   851篇
  2003年   789篇
  2002年   750篇
  2001年   701篇
  2000年   687篇
  1999年   626篇
  1998年   256篇
  1997年   248篇
  1996年   219篇
  1995年   220篇
  1994年   171篇
  1993年   177篇
  1992年   513篇
  1991年   496篇
  1990年   438篇
  1989年   533篇
  1988年   437篇
  1987年   396篇
  1986年   442篇
  1985年   354篇
  1984年   303篇
  1983年   316篇
  1982年   175篇
  1981年   166篇
  1979年   246篇
  1978年   183篇
  1977年   163篇
  1976年   162篇
  1974年   153篇
  1973年   181篇
  1972年   152篇
  1971年   160篇
  1970年   139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We used immunohistochemistry to evaluate four cytologically malignant cutaneous neoplasms on the face or neck of elderly individuals. All four lesions were composed of a dermal proliferation of spindle and pleomorphic giant cells. Differential diagnosis included spindle cell carcinoma, atypical fibroxanthoma, malignant melanoma, leiomyosarcoma, and angiosarcoma. All four neoplasms were strongly immunoreactive for vimentin and negative for cytokeratin, S100 protein, desmin, and factor-VIII-related antigen. Focal immunoreactivity for lysozyme and/or a1-antichymotrypsin was seen in the giant cells of each lesion. These results supported the diagnosis of atypical fibroxanthoma in each instance. Immunohistochemical staining can provide useful information for distinguishing among malignant cutaneous spindle cell tumors.  相似文献   
62.
This study evaluated the changes in renal function that occur during the early phases of chronic infusion of carbachol into the lateral ventricle in conscious rats. Infusion of 1.0 micrograms/h of carbachol i.c.v. resulted in a prompt pressor response with mean arterial pressure rising 20 mm Hg within 15 min. The pressure remained elevated for the duration of a 2-hour infusion. Carbachol infusion at 0.5 micrograms/h induced a similar elevation in blood pressure, but the onset was delayed, reaching significance only after 30-60 min. The higher dose of carbachol was associated with a marked and sustained natriuresis, with sodium excretion increasing from 2.1 +/- 0.3 to 5.3 +/- 1.0 microEq/100 g min after 2 h, compared to 2.0 +/- 0.5 and 1.8 +/- 0.3 microEq/100 g min in vehicle-infused control animals. Sodium excretion did not change significantly in animals infused with carbachol at 0.5 microgram/h. There were no significant changes in glomerular filtration rate in any of the groups. Plasma levels of atrial natriuretic peptide (ANP) were not altered significantly by ventricular infusion of carbachol (188 +/- 99 before vs. 83 +/- 17 pg/ml after infusion). It is concluded that the pressor response to central carbachol infusion is not dependent on retention of sodium and water. The natriuresis observed with carbachol infusion can be dissociated from the pressor response, and is not mediated by ANP.  相似文献   
63.
The authors have developed and patented a neurosurgical retractor system incorporating an infrared emitter and detector that allows detection of cerebral pulsations. Gentle contact with the surface of cat brains shows cerebral pulsations that correlate with arterial pulse as well as mechanical ventilation. The amplitude of cerebral pulsations decreases with higher retraction pressure and disappears at approximately 20 mmHg. The pressure on the surface of the brain decreased 50% in 5 minutes even though the position of the retractor was maintained constant. The authors postulate that monitoring cerebral pulsation may prove useful in clinical neurosurgery with respect to avoiding excessive retraction, which causes brain damage.  相似文献   
64.
65.
OBJECTIVE: To determine whether Helicobacter pylori, a chronic bacterial infection often acquired in childhood, is associated with increased risk of coronary heart disease and stroke later in life. DESIGN: Nested case-control study. SETTING: Prospective study of cardiovascular disease in men aged 40-59 years at entry (1978-1980) in 24 British towns. SUBJECTS: 135 cases of myocardial infarction and 137 cases of stroke occurring before December 1991; 136 controls were identified, frequency matched to cases by town and age group. METHODS: Serum samples stored at entry were analysed by an enzyme linked immunosorbent assay for the presence of H pylori specific IgG antibodies. RESULTS: 95 of the myocardial infarction cases (70%) and 93 (68%) of the stroke cases were seropositive for H pylori compared with 78 (57%) of the controls (odds ratio for myocardial infarction 1.77, 95% confidence interval (CI) 1.06 to 2.95, P = 0.03; odds ratio for stroke 1.57, 95% CI 0.95 to 2.60, P = 0.07). Helicobacter pylori infection was associated with manual social class, residence in Northern England or Scotland, cigarette smoking, higher systolic pressure and blood glucose, and a lower height-standardised forced expiratory volume in one second. Adjustment for these factors attenuated the relation between H pylori and myocardial infarction (odds ratio = 1.31, 95% CI 0.70 to 2.43, P = 0.40) and effectively abolished the relation with stroke (odds ratio = 0.96, 0.46 to 2.02, P = 0.92). The relation between helicobacter infection and fatal myocardial infarction was slightly stronger (odds ratio 2.41, 95% CI 1.13 to 5.12) but was also markedly attenuated after adjustment (1.56, 95% CI 0.68 to 3.61). CONCLUSION: In this prospective study the association between Helicobacter pylori infection and increased risk of myocardial infarction and stroke was substantially confounded by the relation between this infection, adult social class, and major cardiovascular risk factors.  相似文献   
66.
67.
68.
69.
The baroreflex maintains blood pressure through the glossopharyngeal (IX) cranial nerve. We report a 54-year-old man who developed a left sided headache, hoarseness, dysarthria, dysphagia, and sustained hypertension from a left internal carotid artery dissection. We hypothesise that interruption of the left IX nerve caused hypertension in this patient.  相似文献   
70.
A 32–year–old man had an unusual gunshot wound to the leg, causing a peroneal nerve palsy. Sonography provided useful complementary findings to the electrodiagnostic localization of the injury.  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