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   12810篇
  免费   742篇
  国内免费   149篇
耳鼻咽喉   94篇
儿科学   259篇
妇产科学   164篇
基础医学   1960篇
口腔科学   226篇
临床医学   872篇
内科学   3151篇
皮肤病学   175篇
神经病学   1103篇
特种医学   691篇
外国民族医学   1篇
外科学   1768篇
综合类   299篇
预防医学   399篇
眼科学   134篇
药学   1084篇
中国医学   90篇
肿瘤学   1231篇
  2023年   72篇
  2022年   117篇
  2021年   202篇
  2020年   131篇
  2019年   136篇
  2018年   196篇
  2017年   154篇
  2016年   207篇
  2015年   251篇
  2014年   275篇
  2013年   318篇
  2012年   559篇
  2011年   568篇
  2010年   354篇
  2009年   289篇
  2008年   496篇
  2007年   596篇
  2006年   575篇
  2005年   591篇
  2004年   665篇
  2003年   661篇
  2002年   733篇
  2001年   588篇
  2000年   568篇
  1999年   474篇
  1998年   223篇
  1997年   152篇
  1996年   150篇
  1995年   138篇
  1994年   117篇
  1993年   96篇
  1992年   395篇
  1991年   306篇
  1990年   282篇
  1989年   337篇
  1988年   267篇
  1987年   291篇
  1986年   223篇
  1985年   179篇
  1984年   149篇
  1983年   103篇
  1982年   65篇
  1981年   62篇
  1980年   39篇
  1979年   95篇
  1978年   48篇
  1977年   54篇
  1976年   36篇
  1975年   18篇
  1969年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的:在原核系统中表达并纯化大肠杆菌胞嘧啶脱氨酶(cytosine deaminase,CD),制备鼠抗大肠杆菌CD多克隆抗体,方法:亚克隆CD基因到原核表达载体pMAL-c2和pBV222中,并转化入大肠杆菌DH5α内,诱导表达并纯化MBP-CD和6his-CD融合蛋白,用纯化的MBP-CD融合蛋白免疫小鼠制备多克隆抗体。结果:通过重组质粒的酶切筛选出重组阳性克隆,成功地表达和纯化出MBP-CD和6his-CD融合蛋白,用纯化的MBP-CD成功制备了鼠抗CD多克隆抗体,并用6his-CD和GST-CD重组蛋白进行Western印迹分析,证实了抗体的正确性,结论:应用多克隆抗体可以检测体内外CD基因的表达,为临床前和临床上深入开展CD基因的生物治疗研究提供重要的实验材料。  相似文献   
2.
Bronchial venous plexus and its communication with pulmonary circulation   总被引:2,自引:0,他引:2  
This study was undertaken to clarify the microvascular anatomy of the normal human bronchial circulation, focusing on the bronchial venous system and its communication with the pulmonary circulation. Ten normal lungs obtained at autopsy were studied. Bronchial arteriography was performed in six lungs, pulmonary arteriography in two lungs, and pulmonary venography in another two. Using radiologic methods, including microradiography, and serial histologic sections, we found numerous bronchial venous plexuses around the airways and blood vessels into which the bronchial capillaries drained. Frequent communications of the venous plexuses with the pulmonary veins and neighboring alveolar capillaries were also demonstrated. The bronchial venous plexus and its close connection with the pulmonary circulation may be important in various pathologic conditions involving the interstitial space, such as interstitial pulmonary edema.  相似文献   
3.
4.
High-resolution computed tomography (HRCT) findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are varied and nonspecific. There is no known report of changes in HRCT findings and respiratory function test results for RB-ILD patients following the cessation of smoking. Five patients with RB-ILD, confirmed by surgical lung biopsy, were retrospectively studied. Each stopped cigarette smoking and did not receive corticosteroid therapy after diagnosis. The clinical symptoms, respiratory function test results and HRCT findings obtained at the final observation were compared with those from the time of diagnosis. Ground-glass opacity and centrilobular nodules corresponding to pathological respiratory bronchiolitis, as well as intralobular fine linear-reticular opacity corresponding to fibrosis involving the subpleural alveolar septa, showed computed tomography-pathological correlations. Both clinical symptoms and the diffusing capacity of the lungs for carbon monoxide improved significantly following smoking cessation, as did ground-glass opacity and centrilobular nodules seen during the initial HRCT examination. Centrilobular nodules and ground-glass opacity, which are the main features of high-resolution computed tomography of respiratory bronchiolitis-associated interstitial lung disease patients and represent pathological respiratory bronchiolitis, can be improved by smoking cessation. The diffusing capacity of the lung for carbon monoxide in respiratory function tests can be also improved.  相似文献   
5.
AIMS: A rare case of the insulin autoimmune syndrome (IAS) accompanied by insulin receptor anomaly is reported. METHODS: Antibodies to insulin and insulin receptor were determined in the patient with severe hypoglycaemia before and after the treatment with prednisolone. RESULTS: Titers of antibody to insulin and insulin receptors were 73.0% and 41.5%, respectively. Drug-induced lymphocyte stimulation tests were all negative for the suspicious drugs. Her HLA-DR was DRB1*0403/04051. Following steroid therapy, the formation of antibodies was suppressed and alleviated her symptoms. Scatchard analysis yielded findings specific to polyclonal antibodies. CONCLUSIONS: The changes in autoantibodies resulted in alleviation of the hypoglycemic symptoms as a result of steroid therapy.  相似文献   
6.
Two antifungal antibiotics maniwamycins A and B were isolated from the culture broth of a strain of actinomycetes, which were classified as Streptomyces prasinopilosus. These antibiotics were isolated by resin absorption and extraction with EtOAc and purified by column chromatography. Both antibiotics were found to be new azoxy substances from their physico-chemical properties. They showed broad antifungal spectra.  相似文献   
7.
We experienced a rare case of giant cell tumor (GCT) arising in the 5th rib involving the 5th vertebral body and transverse process. A 57-year-old man presented with a well-defined mass in the left thoracic cavity on chest x ray examination. Chest computed tomography showed a heterogeneous 7cm-diameter mass originating in the posterior segment of the left 5th rib. The tumor had spread to the 5th thoracic vertebra destroying the left half of the body and transverse process. Magnetic resonance imaging showed a heterogeneous-intensity mass involving the 4th to 6th ribs. A radical excision of the tumor followed by a 50 Gy radiotherapy was performed after embolization of the feeding arteries. The pathological diagnosis was a GCT. The patient remains well without evidence of recurrence for 6 years following surgery. The present case is only the 14th case of GCT arising in the rib to have been reported in Japan.  相似文献   
8.
目的:分析胃癌大肠转移的X线钡灌肠表现。方法:104例胃癌入院术前检查发现结肠转移或胃癌术后转移入院治疗的病例。分析钡灌肠初次发现大肠转移征象的年龄、发现胃癌原发病变距初次发现大肠转移的间隔时间、转移病变的发生部位和病变造成的X线钡灌肠图像上的肠管变形和粘膜面的改变。结果:104例胃癌结肠转移,男67例,女37例。胃癌术前检查中发现结肠转移者32例,术后发现的大肠转移中,多数转移发生在手术后3年内(占91.3%)。胃癌原发灶的肉眼形态BorrmannⅢ型(28例)和BorrmannⅣ型(65例)者占89.4%,组织学中以低分化腺癌和印戒细胞癌为主要成分者占91.3%。X线钡灌肠检查显示大肠转移的好发部位为横结肠(80),其次为直肠(50)。转移灶可累及多节段肠管,其中横结肠中1/3段(47),横结肠左1/3(44),横结肠右1/3(39)和直肠腹膜返折之上(39)。X线显示肠管单侧变形者227处,双侧变形者96处。黏膜面表现为梳齿状黏膜纹聚集改变253处,颗粒结节状改变23处,外压性改变20处,弥漫性改变62处。结论:胃癌大肠转移的好发部位为横结肠和直肠,结肠黏膜面的梳齿状黏膜纹聚集为胃癌大肠转移的主要X线钡剂灌肠表现。  相似文献   
9.
10.
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