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   62320篇
  免费   5405篇
  国内免费   1964篇
耳鼻咽喉   733篇
儿科学   827篇
妇产科学   1262篇
基础医学   9614篇
口腔科学   1542篇
临床医学   5562篇
内科学   11587篇
皮肤病学   1444篇
神经病学   4289篇
特种医学   2177篇
外国民族医学   13篇
外科学   8212篇
综合类   4801篇
现状与发展   2篇
一般理论   9篇
预防医学   3598篇
眼科学   1652篇
药学   6049篇
  5篇
中国医学   1234篇
肿瘤学   5077篇
  2023年   334篇
  2022年   687篇
  2021年   997篇
  2020年   666篇
  2019年   991篇
  2018年   1506篇
  2017年   1198篇
  2016年   1289篇
  2015年   1550篇
  2014年   1974篇
  2013年   2221篇
  2012年   3149篇
  2011年   3025篇
  2010年   1795篇
  2009年   1695篇
  2008年   2434篇
  2007年   2496篇
  2006年   2232篇
  2005年   1921篇
  2004年   1666篇
  2003年   1620篇
  2002年   1495篇
  2001年   4747篇
  2000年   4668篇
  1999年   4049篇
  1998年   1458篇
  1997年   1084篇
  1996年   664篇
  1995年   562篇
  1994年   488篇
  1993年   444篇
  1992年   1982篇
  1991年   1710篇
  1990年   1556篇
  1989年   1513篇
  1988年   1318篇
  1987年   1213篇
  1986年   1074篇
  1985年   914篇
  1984年   593篇
  1983年   477篇
  1982年   255篇
  1981年   183篇
  1980年   143篇
  1979年   288篇
  1978年   80篇
  1974年   78篇
  1973年   98篇
  1972年   72篇
  1970年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The authors reviewed the radiographic manifestations of 17 cases of parosteal osteosarcoma, with pathologic correlation in 15. There were two types of parosteal osteosarcoma radiologically. The majority of cases were type I with uniformly dense masses which had regular borders. They often adhered to the cortex and showed no evidence of soft-tissue invasion which correlated with low-grade pathologic malignancy and a relatively benign clinical course. Type II involved the bone, soft-tissue and the medullary cavity. These lesions were poorly differentiated and frequently accompanied by metastatic lesions.
  相似文献   
72.
73.
This paper is a summary of our observations on 105 cases of infantile spasms. The age of onset was around six months after birth, but the patients came for treatment mainly about one year after onset. Fever of unknown cause, asphyxia, birth injury, infection of the central nervous system, tuberous sclerosis, phenylketonuria and recent immunization etc. were complained. Clinically, it is characterized by head nodding, mental retardation, myoclonic jerks and various neurologic deficits. EEG findings showed classical or modified arrythmia or other epileptiform patterns. About one third of 22 cases examined had abnormal brain stem auditory evoked potentials. Among 42 patients who underwent CT scanning before ACTH treatment, 18 were normal and 7 abnormal; during ACTH treatment 3 normal and 4 abnormal; after completion of treatment, 4 normal and 6 abnormal, suggesting no further atrophy of the brain. Examination of trace elements of the hair by particle-induced X-ray emission (PIXE) method in 23 patients revealed a significant difference in lead, calcium and zinc contents between patients and 101 controls, but no statistical difference in iron and copper contents between the two groups. Sodium valproate, prednisone and ACTH appear to be effective in the treatment of infantile spasms. Eight patients fully recovered, and they can go to school without difficulty. Many patients derived various degrees of improvement to the satisfaction of their parents. Two patients were still amented and often attacked by myoclonus. The effects, side effects of these drugs, and the possible pathogenesis were discussed.
  相似文献   
74.
The effects of some antirheumatics on the formation and retraction of collagen lattices seeded with fibroblasts have been studied. Among the antirheumatics, diclofenac was the most active inhibitor of lattice retraction, then tropesin and to a lesser extent indomethacin. Ibuprofen which is known as a very slight inhibitor of protein synthesis was able to significantly enhance lattice retraction when 10 micrograms/ml (48.5 microM) and 50 micrograms/ml (242 microM) were used.  相似文献   
75.
76.
77.
Tick-borne encephalitis (TBE) virus is an important human pathogenic flavivirus that is endemic in Europe and Asia. The disease can be effectively prevented by inactivated vaccines and vaccination breakthroughs (VBTs) are rare. We investigated the characteristics of antibody responses in such VBTs in comparison to those in unvaccinated TBE patients. In contrast to the unvaccinated controls, most of the VBTs displayed a delayed IgM antibody response and had high avidity and strongly neutralizing antibodies already in the first sample taken upon hospitalization. The antibody profile of these patients therefore had the characteristics of an anamnestic immune response. In the VBTs analyzed, immunological priming and memory were apparently not sufficient or fast enough to prevent the disease.  相似文献   
78.
The recent global resurgence of mumps has drawn attention to the continued need for robust mumps immunization programs. Unfortunately, some vaccines derived from inadequately attenuated vaccine strains of mumps virus have caused meningitis in vaccinees, leading to withdrawal of certain vaccine strains from the market, public resistance to vaccination, or in some cases, cessation of national mumps vaccination programs. The most widely implicated mumps vaccine in cases of postvaccination meningitis is derived from the Urabe AM9 strain, which remains in use in some countries. The Urabe AM9 vaccine virus has been shown to exhibit a considerable degree of nucleotide and amino acid heterogeneity. Some studies have specifically implicated variants containing a lysine residue at amino acid position 335 in the hemagglutinin-neuraminidase (HN) protein with neurotoxicity, whereas a glutamic acid residue at this position was associated with attenuation. To test this hypothesis we generated two modified Urabe AM9 cDNA clones coding either for a lysine or a glutamic acid at position 335 in the HN gene. The two viruses were rescued by reverse genetics and characterized in vitro and in vivo. Both viruses exhibited similar growth kinetics in neuronal and non-neuronal cell lines and were of similar neurotoxicity when tested in rats, suggesting that amino acid 335 is not a crucial determinant of Urabe AM9 growth or neurovirulence.  相似文献   
79.
OBJECTIVE: A comprehensive study was performed to evaluate the accuracy of a newly developed CT-free, intra-operative planning and navigation system for anterior spine surgery. MATERIALS AND METHODS: Instruments and an image intensifier were tracked using the SurgiGATE navigation system. A laboratory study was performed on 27 plastic vertebrae. Fiducial markers were implanted in the vertebrae for accuracy evaluation purposes, and a dynamic reference base was placed on the vertebrae to establish a patient coordinate system (P-COS). Two fluoroscopic images were used for intra-operative planning. The graft bed plan was recorded in P-COS, followed by surgical formation of the graft bed, which was visualized. To evaluate the accuracy, the vertebrae were scanned with CT, and the markers were used to calculate an accurate paired-point registered transformation between the CT coordinate system and P-COS. RESULTS: Using the new SPO module, accurate planning and navigation of a resection of the vertebral body is possible using two fluoroscopic images. The overall mean error between the planned resection volume and the actual resection was 0.98 mm. In addition, the module can serve as an educational tool for training spine surgeons. CONCLUSIONS: The new fluoroscopy-based system can be used safely for accurate performance of anterior resection during spondylodesis. New methods for safe and accurate registration during anterior spine surgery need to be developed.  相似文献   
80.
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