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   71294篇
  免费   5977篇
  国内免费   2147篇
耳鼻咽喉   787篇
儿科学   939篇
妇产科学   1640篇
基础医学   10632篇
口腔科学   1811篇
临床医学   6482篇
内科学   14033篇
皮肤病学   1224篇
神经病学   4927篇
特种医学   2154篇
外国民族医学   9篇
外科学   9913篇
综合类   5435篇
现状与发展   4篇
一般理论   10篇
预防医学   4023篇
眼科学   2112篇
药学   6266篇
  6篇
中国医学   1314篇
肿瘤学   5697篇
  2023年   420篇
  2022年   774篇
  2021年   1230篇
  2020年   800篇
  2019年   1111篇
  2018年   1680篇
  2017年   1364篇
  2016年   1349篇
  2015年   1622篇
  2014年   2076篇
  2013年   2494篇
  2012年   3520篇
  2011年   3549篇
  2010年   2132篇
  2009年   1943篇
  2008年   2918篇
  2007年   3035篇
  2006年   2944篇
  2005年   2597篇
  2004年   2263篇
  2003年   2102篇
  2002年   2021篇
  2001年   5143篇
  2000年   5046篇
  1999年   4370篇
  1998年   1553篇
  1997年   1188篇
  1996年   765篇
  1995年   610篇
  1994年   559篇
  1993年   486篇
  1992年   2134篇
  1991年   1859篇
  1990年   1691篇
  1989年   1626篇
  1988年   1411篇
  1987年   1297篇
  1986年   1154篇
  1985年   959篇
  1984年   631篇
  1983年   497篇
  1982年   294篇
  1981年   219篇
  1980年   176篇
  1979年   316篇
  1978年   109篇
  1975年   81篇
  1974年   88篇
  1973年   109篇
  1972年   81篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
84.
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   
85.
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   
86.
Epiphrenic diverticulum is rare, comprising of about 10% of all esophageal diverticula. Carcinoma arising within such a diverticulum is even less common. We report on two patients with squamous cell carcinoma arising from an epiphrenic diverticulum. Some features of malignant change related to the epiphrenic diverticula were misdiagnosed or missed in our cases and other reports due to lack of clinical experience. It is important to exclude the possibility of malignancy as this is vital for surgical planning. Although the prognosis for patients with malignancy arising from an epiphrenic diverticulum is generally poor, a high index of suspicion may increase the chance of cure.  相似文献   
87.
咬肌与颅面形态的关系   总被引:3,自引:0,他引:3  
目的探讨咬肌与颅面形态之间的关系,了解咬肌体积与邻近骨骼结构的大小及形态的相关性。方法对40例要求改变脸型者进行磁共振成像(MRI)测量,人体测量,头部正位、侧位和下颌骨曲面断层X线检查,测量并计算咬肌体积(MsV),测量头长(HL)、头宽(HB)、面长(FL)、面宽(FB)、下颌角间宽(IB)、下颌骨体长(CL)、下颌角切线长(MAL)、下颌角角度(JA),计算颜面形态指数FI(FL/FB)、头颅指数C(IHB/HL)。用SPSS11.5软件统计分析MsV与HI。HB、FL、FB、IB、CL、MAL、JA、FI、CI之间的相关性。结果MsV与JA呈明显负相关,与CL、MAL、IB、FB、HL呈明显正相关,与CL、FI、HB无明显相关性。结论咬肌肥大可能是方脸面型的成因之一,是影响面型的重要因素。  相似文献   
88.
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   
89.
90.
Three patients who presented with scrotal swelling within a few days of inguinal herniorrhaphy are reported. Ultrasonography scans performed in these patients all demonstrated features suspicious of recurrence of hernia. One patient underwent surgical exploration, which revealed only a scrotal haematoma without evidence of recurrent hernia. The other two patients were managed conservatively because clinically the swellings were regarded to be more compatible with haematoma. Both patients had subsequent resolution of the scrotal swelling with no clinical evidence of recurrence of hernia on follow‐up. It is concluded that sonographic diagnosis of recurrence of hernia shortly after inguinal herniorrhaphy can occasionally be misleading.  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