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   18948篇
  免费   2053篇
  国内免费   23篇
耳鼻咽喉   152篇
儿科学   640篇
妇产科学   653篇
基础医学   2659篇
口腔科学   358篇
临床医学   2239篇
内科学   3816篇
皮肤病学   197篇
神经病学   1420篇
特种医学   640篇
外科学   2600篇
综合类   598篇
一般理论   43篇
预防医学   2299篇
眼科学   294篇
药学   1372篇
中国医学   17篇
肿瘤学   1027篇
  2021年   321篇
  2020年   205篇
  2019年   307篇
  2018年   348篇
  2017年   273篇
  2016年   263篇
  2015年   286篇
  2014年   428篇
  2013年   645篇
  2012年   844篇
  2011年   957篇
  2010年   507篇
  2009年   482篇
  2008年   774篇
  2007年   818篇
  2006年   752篇
  2005年   797篇
  2004年   732篇
  2003年   719篇
  2002年   686篇
  2001年   617篇
  2000年   645篇
  1999年   555篇
  1998年   274篇
  1997年   217篇
  1996年   235篇
  1995年   211篇
  1994年   177篇
  1993年   173篇
  1992年   437篇
  1991年   479篇
  1990年   443篇
  1989年   414篇
  1988年   358篇
  1987年   385篇
  1986年   357篇
  1985年   341篇
  1984年   284篇
  1983年   243篇
  1982年   156篇
  1981年   144篇
  1979年   194篇
  1978年   149篇
  1977年   150篇
  1976年   123篇
  1975年   117篇
  1974年   183篇
  1973年   163篇
  1972年   131篇
  1970年   133篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Extracranial paranasal spread of meningiomas is uncommon. We describe the management of four cases, all of which first presented to an oto-rhino-laryngologist for an opinion. We suggest that greater use of modern imaging techniques could lead to earlier diagnosis. The natural history of extracranial spread is relatively benign but the management of regrowth of residual disease is difficult. We therefore suggest radical surgery in the first instance provided that the patients general health and configuration of the tumour allow.  相似文献   
62.
63.
We report a case of an infantile myofibromatosis with hemangiopericytoma-like features arising in the tongue of a 5-month-old female infant. Many authors now classify neoplasms as infantile myofibromatosis that were previously called infantile hemangiopericytoma. The ultrastructural features of our tumor illustrate its biphasic nature and provide a possible explanation for its histogenesis. Infantile myofibromatosis, including those diagnosed as infantile hemangiopericytomas, rarely arise in any intraoral location. Despite the generally good prognosis associated with these neoplasms, complete surgical excision is recommended to avoid recurrences.  相似文献   
64.
The α-inhibin gene has been shown in knockout mouse models to be a suppressor of granulosa tumorigenesis in the mouse. To determine if α-inhibin has the same function in humans, we have assessed the frequency of loss of heterozygosity (LOH) of the α-inhibin gene locus on chromosome 2q in 17 human granulosa cell tumors and 36 epithelial ovarian cancers. LOH was detected in 12 of 36 (33.3%) epithelial tumors but in only 1 of 17 (6%) granulosa cell tumors. These data suggest that in contrast to the suggestions from the mouse model α-inhibin does not function as a granulosa cell tumor suppressor gene in the human. Furthermore, analysis of the TP53 gene in the granulosa cell tumors failed to detect either LOH or point mutations, indicating that they have a developmental pathway distinct from that of epithelial ovarian tumors.  相似文献   
65.
66.
67.
A series of dihydropyridines substituted at the 2-position by basic side chains are described and their potencies as calcium antagonists listed. One compound, 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-3-ethoxycarbonyl-5- methoxycarbonyl-6-methyl-1,4-dihydropyridine (17, amlodipine) was found to be comparable in potency to nifedipine and to have an elimination half-life of 30 h in dogs. Oral bioavailability approached 100%, and hemodynamic responses were gradual in onset and long-lasting in effect. The two enantiomers have been prepared, and the bulk of the activity was found to reside with the (-) isomer, 18. X-ray crystallographic studies, carried out on a close analogue of 17, suggest the existence of a weak hydrogen bond between the side-chain oxygen and the proton on the ring nitrogen.  相似文献   
68.
To examine the efficacy of modified stroma-free hemoglobin in maintaining liver PO2, rats were exchange-transfused to hematocrit 10% using pyridoxalated polymerized hemoglobin (plp-polyHb, 10-12 g/dl) prepared from crystalline Hb. Following hemodilution, plasma Hb was 7.4 g/dl, and rats were normotensive. Mean liver PO2 was 3.4 vs 23.3 mm Hg in sham-exchanged controls. Other rats, hemodiluted similarly with 6% albumin or hydroxyethylstarch, were hypotensive and died. At 24 hours plasma Hb was 2.0 g/dl, indicating an intravascular half-life of approximately 16 hours. Hepatic PO2 was 12.4 vs 26.8 mm Hg in nonhemodiluted controls. Data provided by clearance of low-dose indocyanine green suggested reduced plasma volume and depressed liver blood flow. Scattered foci of midzonal hypoxic damage were observed in liver lobules. The basis for hypoxic injury is considered to be due in part to the acute restriction of oxygen supply induced by exchange-transfusion with plp-polyHb. The rate of loss of intravascular hemoglobin and diminished plasma volume could have contributed to oxygen insufficiency as well. Endotoxin present in the plp-polyHb was not a factor.  相似文献   
69.
One hundred patients with cirrhosis underwent abdominal computed tomography (CT) using a delayed contrast technique to determine liver and spleen volume. These scans were reviewed to screen this "at risk" population for hepatocellular carcinoma (HCC). Fifteen of the 100 screened patients had focal abnormalities suspicious for HCC. On biopsy, only 1 patient was shown to have HCC. The other 14 patients had either fatty infiltration or focal regeneration. In the same time interval, a total of 10 patients had histologically proven HCC. All presented with symptoms and died within 4 months of diagnosis. The results show that focal hepatic lesions can be detected by CT but in this population the lesions may not be due to HCC. The incidence of HCC was approximately 1%, probably reflecting a truly low incidence in this population.  相似文献   
70.
Petit mal-grand mal (PM-GM) electroconvulsive therapy (ECT) is a technique developed by Impastato to elicit unconsciousness with a subconvulsive electrical stimulus, rather than with barbiturate anesthesia. Muscle relaxation is produced with succinylcholine chloride before stimulus is applied. The cases reported here illustrate applications of the technique to depressed patients with severe cardiac and pulmonary disease, and the use of PM-GM ECT in a patient in whom seizures could not be elicited by the usual ECT technique is described.  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