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   278964篇
  免费   23191篇
  国内免费   6471篇
耳鼻咽喉   3437篇
儿科学   5887篇
妇产科学   4462篇
基础医学   23610篇
口腔科学   7636篇
临床医学   30327篇
内科学   32146篇
皮肤病学   2747篇
神经病学   14066篇
特种医学   8687篇
外国民族医学   15篇
外科学   25987篇
综合类   46078篇
现状与发展   15篇
一般理论   24篇
预防医学   32333篇
眼科学   2735篇
药学   27089篇
  407篇
中国医学   30376篇
肿瘤学   10562篇
  2024年   911篇
  2023年   4846篇
  2022年   9207篇
  2021年   12709篇
  2020年   12202篇
  2019年   13209篇
  2018年   11933篇
  2017年   10612篇
  2016年   9808篇
  2015年   9342篇
  2014年   18181篇
  2013年   19005篇
  2012年   16331篇
  2011年   17525篇
  2010年   14114篇
  2009年   12319篇
  2008年   11803篇
  2007年   12058篇
  2006年   10447篇
  2005年   9093篇
  2004年   7689篇
  2003年   6884篇
  2002年   5592篇
  2001年   4907篇
  2000年   4255篇
  1999年   3555篇
  1998年   2998篇
  1997年   2930篇
  1996年   2374篇
  1995年   2331篇
  1994年   2146篇
  1993年   1757篇
  1992年   1657篇
  1991年   1494篇
  1990年   1270篇
  1989年   1211篇
  1988年   1155篇
  1987年   996篇
  1986年   928篇
  1985年   2352篇
  1984年   2522篇
  1983年   1581篇
  1982年   2128篇
  1981年   1497篇
  1980年   1295篇
  1979年   1122篇
  1978年   914篇
  1977年   712篇
  1976年   835篇
  1975年   549篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
The immunohistochemical occurrence of the high affinity neurotrophin (NT) receptors trkA, trkB, and trkC is shown in the pre-term newborn, infant, and adult human post-mortem cerebellum. Immunoreactive neuronal perikarya and processes were observed in all specimens examined, where they appeared unevenly distributed in the cerebellar cortical layers and deep nuclei, and showed regional differences among cerebellar lobules and folia. The trk receptor-antibodies, tested by Western blot on human cerebellum homogenates, revealed multiple immunoreactive bands for trkA and single bands for trkB and trkC. The results obtained show the tissue localization of the trk receptor-like immunoreactivity in the human cerebellum from prenatal to adult age. The analysis for codistribution of the receptors with the relevant ligand and among the receptors in discrete cortical and deep nuclei tissue fields shows a wide variety of conditions, from a good similarity in terms of type and density of labeled structures, to a lack of correspondence, and suggests the possibility of colocalization of trk receptors with the relevant neurotrophin and among them in the cerebellar cortex. These results sustain the concept that the neurotrophin trophic system participates in the development, differentiation, and maintenance of the human cerebellar connectivity and support the possibility of a multifactorial trophic support for the neurotrophins through target-derived and local mechanisms.  相似文献   
972.
生物化学与细胞生物学课程整合的探讨   总被引:8,自引:0,他引:8  
为了适应新世纪教学内容和课程体系改革的要求,我校借鉴美国哈佛大学医学院的经验,将生物化学与细胞生物学两门课程整合为“细胞的化学与生物学”。整合后在减少两个学科间重复内容、增加学科间联系、减少学时、早期接触临床、培养学生分析解决问题的能力、创新能力等方面有了很大改进,为这两门课程的改革开辟了新途径。  相似文献   
973.
AnAnalysisofChromosomeonSterilityCausedbyAzoospermiaorOligospermia¥WuMeiheng;TangWingnuo.(ACTAACADEMIAEMEDICINAENANJING,1995(...  相似文献   
974.
以史为鉴,直面SARS   总被引:1,自引:1,他引:0  
回顾影响我国古代疫病流行的各种因素,直接面对这次SARS危机,可以引出以下思考:①要尽快有效地战胜一种传染力极强的疫病,必须是一种政府行为,必须有一个有高度取信于民,而又敢于负责,务实高效的政府来统一领导。②应该珍惜安定团结的政治局面,努力发展生产,只有拥有了可靠的物质保障,才能有经得起风浪的能力。③合理控制人口、规划大城市的建设规模,是有效防疫的必要措施,这项工作做不好,很大程度上增加了防疫工作的难度,本次发生在我国大城市的SARS爆发流行值得警惕。  相似文献   
975.
某医科大学中老年教职工健康状况分析   总被引:6,自引:0,他引:6  
对1004名50岁以上中老年教职工进行健康检查。结果:健康者仅占11.25%,而88.75%的中老年教职工至少患有1例次疾病,最多患有5例次疾病,总例次患病率为186.95%,男女例次患病率分别为187.24%和186.62%,男女间无差异。前5位疾病的顺位是:心血管疾病、呼吸系疾病、脑血管疾病、消化系统病、泌尿生殖疾病。  相似文献   
976.
977.
文章对33例中老年肺尖和锁骨下区慢性结核作平片和肺尖断层对照分析。结果表明:断层对该部位慢性结核多形态病灶检出率和病情判断明显优于平片。着重对空洞、结核球和合并肺癌断层影像研究。肯定断层诊断价值。  相似文献   
978.
Background. Partial harvesting of the left internal mammary artery (LIMA) is a widespread technique used during minimally invasive coronary operations performed through a left anterior small thoracotomy. The influence of persisting LIMA branches was investigated to evaluate their effect on the blood flow of the left anterior descending artery.

Methods. Thirty patients, 15 with totally (group A) and 15 with partially (group B) harvested LIMAs, were evaluated. All the patients underwent postoperative angiography, during which a flow map of the LIMA was performed. The average peak velocity and the diastolic-to-systolic peak velocity ratio were recorded. The LIMA graft flow pattern was recorded in the proximal and distal thirds of the artery. Intramammary adenosine (12 to 14 μg) was injected and the average peak velocities before and after injection were calculated.

Results. The average peak velocity was similar in both groups in the proximal and distal thirds of the LIMA (25 ± 7 and 26 ± 5 cm/sec, respectively, in group A versus 27 ± 5 and 25 ± 5 cm/sec, respectively in group B; p = NS). The diastolic-to-systolic peak velocity ratio was similar proximally (0.78 ± 0.3 in group A versus 0.69 ± 0.3 cm/s in group B; p = NS), but not distally (1.72 ± 0.1 in group A versus 0.97 ± 0.3 in group B; p < 0.0005). The LIMA graft flow reserve was similar both proximally and distally (2.6 ± 0.6 and 2.5 ± 0.3 cm/s, respectively, in group A versus 2.6 ± 0.5 and 2.6 ± 0.3 cm/s, respectively, in group B; p = NS).

Conclusions. The persistence of LIMA branches does not influence the blood flow of the left anterior descending artery after acute adenosine-induced myocardial hyperemia. If a left anterior small thoracotomy is used in left anterior descending artery direct revascularization, complete LIMA harvesting is not mandatory and depends on the personal preference of the surgeon.  相似文献   

979.
A lymph node metastasis in the neck or parotid region from an unknown primary melanoma is an uncommon occurrence. Out of a total of 300 patients with head and neck melanoma treated at the Netherlands Cancer Institute between 1976 and 1992, 17 (5.7%) presented in this way. The most common site for metastatic lymph nodes (18 nodes in 17 patients) was level V (n= 7), followed by the parotid region (n= 4), level II (n= 4), level III (n= 2), and level IV (n= 7). Two patients had local excision of the neck node metastasis only, while the remaining 15 patients underwent more extensive surgical treatment. The 5-year disease-specific survival rate in this group was 48%, with a median survival of 36 months, which is more or less similar to the prognosis of stage II melanoma of the head and neck with a known, surgically treated primary tumour. No relation was found between disease-free interval and sex, the number of positive lymph nodes or the duration of symptoms.  相似文献   
980.
The subcellular distribution of the blood group antigen A in the transitional epithelium of the urinary tract and its neoplastic growths was studied using transmission immuno-electronmicroscopy. Sixty-five tissue specimens from 50 blood group A1 patients were processed according to an immunogold procedure which was optimized for preservation of both antigen and ultrastructure. The reactions were stronger in the glycocalyx of the luminal surfaces and at the interdigitating cytoplasmic processes of the cells. In the intracellular compartment the reactions were associated with tubulovesicular membrane-bound structures and with the Golgi complexes. Secretory products, intra- or extra-cellular, were also positive. The greatest variability was noted in the cell surface reactions, which were positive in 88% of normal but only 41% of neoplastic urothelial specimens. An inverse correlation was found between malignant behaviour and cell surface, but not intracellular, reactions. We conclude that, in transitional cell carcinomas, there is a quantitative defect in the processing of substance A which affects predominantly the cell surface component and may involve either the transport-insertion steps, the plasma membrane-associated glycosyltransferases or internalization of blood group antigen A.  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