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   343383篇
  免费   28717篇
  国内免费   4121篇
耳鼻咽喉   3785篇
儿科学   9232篇
妇产科学   9412篇
基础医学   94007篇
口腔科学   11609篇
临床医学   24925篇
内科学   54600篇
皮肤病学   11748篇
神经病学   18041篇
特种医学   10537篇
外国民族医学   75篇
外科学   44435篇
综合类   10893篇
现状与发展   19篇
一般理论   21篇
预防医学   6919篇
眼科学   3838篇
药学   10268篇
  25篇
中国医学   564篇
肿瘤学   51268篇
  2023年   5963篇
  2022年   8526篇
  2021年   11005篇
  2020年   10969篇
  2019年   7995篇
  2018年   9896篇
  2017年   10081篇
  2016年   10519篇
  2015年   12100篇
  2014年   21197篇
  2013年   19214篇
  2012年   15149篇
  2011年   16184篇
  2010年   16923篇
  2009年   15911篇
  2008年   12577篇
  2007年   12824篇
  2006年   11736篇
  2005年   10931篇
  2004年   9949篇
  2003年   9436篇
  2002年   9226篇
  2001年   9243篇
  2000年   8851篇
  1999年   8384篇
  1998年   5128篇
  1997年   4292篇
  1996年   4329篇
  1995年   3764篇
  1994年   3349篇
  1993年   3097篇
  1992年   6464篇
  1991年   6350篇
  1990年   6218篇
  1989年   5865篇
  1988年   5703篇
  1987年   3092篇
  1986年   1542篇
  1985年   1981篇
  1984年   1909篇
  1983年   1674篇
  1982年   1585篇
  1981年   1389篇
  1980年   1319篇
  1979年   1251篇
  1978年   1182篇
  1977年   943篇
  1976年   847篇
  1974年   870篇
  1973年   849篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A 86-year-old man was admitted to our hospital because of swallowing disturbance and deterioration of consciousness. He had been aware of hearing disturbance on the right side for twelve months. Computed tomography (CT) scan demonstrated an inhomogeneous hyperdense mass lesion, 3.2 X 2.3 cm in size, at the right cerebello-pontine angle, and ventricular enlargement with intraventricular hemorrhage. Skull tomogram revealed destructive enlargement of the right jugular foramen. The angiogram showed avascular mass with elevation of anterior inferior cerebellar artery, and downward shift of posterior inferior cerebellar artery. Operative and histological findings were compatible with glossopharyngeal neurinoma of Antoni type A dominance. This tumor had numerous abnormal vessels probably causing massive hemorrhage. Only fifteen cases of intracranial neurinoma with symptomatic hemorrhage have been reported in the world literature. This case is reported as the sixteenth one and the first glossopharyngeal neurinoma among them. Possible etiology of such hemorrhage is discussed.  相似文献   
992.
993.
以聚合酶链反应(PCR)法在mRNA水平检测T淋巴细胞受体α链可变区基因表达为例,介绍用~(32)P标记的人工合成寡核苷酸探针对PCR产物特异性作阳性证实的方法。该法以干琼脂糖凝胶作为支持物、相对较为简便和省财。用Ca探针以干凝胶作支持物的杂交结果,证实29个Vα基因的PCR扩增中物均为特异性的,放射自显影的带型与位置和溴乙锭染色所示完全吻合。  相似文献   
994.
Granular cell tumors (GCT) are rare neoplasms, and only 173 cases of benign GCT of the breast have been documented. We report herein the cases of two patients with this tumor and discuss the methods of diagnosis and treatment. The first patient was a 60-year-old woman who presented with a firm ill-defined mass in her left breast. Mammography showed a dense shadow with spicula and skin thickness, and ultrasonography revealed a hypoechoic mass with an irregular border. Radical mastectomy was performed under the wrong preoperative diagnosis of breast cancer. The second patient was a 31-year-old woman who presented with an elastic-hard mass in her left breast. Mammography showed a well-demarcated dense mass, and ultrasonography revealed a well-defined hypoechoic mass with a large depth-width ratio. Fine-needle aspiration cytology (FNAC) showed a large number of histiocytic cells with abundant granular cytoplasm. An excisional biopsy was performed, and histological examination confirmed a diagnosis of GCT. GCT is benign, but often misdiagnosed as breast cancer both clinically and radiologically. Therefore, histological examination is essential for making a correct diagnosis, while FNAC is also useful. Local resection is still the treatment of choice, and surgeons should do their utmost to avoid performing needless radical mastectomy.  相似文献   
995.
应用放射免疫测定法,对20例胃肠癌患者进行了血清癌胚抗原(CEA)测定,并应用免疫组化法对其中16例癌组织中的CEA进行了检测.检测结果,血清CEA阳性6例,癌组织CEA阳性9例.低分化癌的血清CEA显著高于高分化癌(P<0.05).血清CEA与癌灶部位、癌组织CEA与分化程度及血清CEA均无关(P>0.05).提示血清CEA的含量与癌组织的分化程度有关,血清CEA与癌组织内的CEA无平行关系.作者并对其机制及检测CEA的意义进行讨论.  相似文献   
996.
BACKGROUND:: A soluble 105 kD neu-related protein is detectable in conditionedmedium from breast cancer cells expressing the neu-oncogeneproduct and in serum of nude mice bearing tumors that overexpressneu-oncogene PATIENTS AND METHODS:: In 100 patients with primary (n - 33) relapse-free (n - 6) andmetastatic (n - 61) breast carcinoma the serum levels of thesoluble new-related protein were investigated by ELISA techniques.Median age was 57 years, range 26–89 years. RESULTS:: The neu-protein serum levels were below 40 HNU/ml (human neu-antigenunit) in 72 patients and 40 or more HNU/ml in 28 patients. In30 patients with primary breast carcinoma, tested before mastectomy,all serum- neu-protein samples were negative. However, 26 of61 metastazised patients (43%) were serum-neu-protein-positive.In disseminated disease (n – 61), serum-neu-protein-positivitywas more likely to be seen in patients with visceral metastases(18/33 – 54%), than in patients with nonvisceral metastases(8/28 – 28%). Furthermore, monitoring of the serum-neu-proteinlevels reflected clinical course. For 53 patients original paraffin-embeddedtumor material was available for studying immunohistochemicalneu-protein expression. In 39/53 (73%) patients immunohistochemicaland ELISA data showed corresponding results. In 27/30 (90%)patients, from whom sera and tissue could be obtained at thesame time at primary mastectomy, results of immunohistochemistryin primary tumor and serum ELISA were negative and mutuallyconfirmatory. However, the other three patients were positivefor immunohistochemical neu-protein expression in primary tumorbut negative for serum-neu-protein expression. CONCLUSIONS:: Our results suggest that patients with advanced breast cancerand an elevated serum-neu-protein level may have a poor clinicaloutcome. This test might be a useful tool for monitoring patientswith advanced breast carcinoma, but not those with early disease.Further prospective studies are warranted to elucidate the questionof whether this test can contribute to determining prognosisand treatment strategies. breast carcinoma, c-erb-B2, HER-2, neu, oncogene, pl85  相似文献   
997.
The bone marrow (BM) and peripheral blood (PB) samples of 71 patients with plasma cell dyscrasias were analysed by the Southern blot technique for the presence of clonal immunoglobulin (Ig) gene rearrangements. 53% of BM samples examined were archival material such as air dried BM slides or frozen trephine biopsies. The results were related to bone marrow plasmacytosis as determined by cytology and flow cytometry, and other clinical parameters. Clonal Ig gene rearrangements were found in BM samples of 45 (83%) of 54 MM patients and in 3 of 6 patients with monoclonal gammopathy of unknown significance (MGUS). Clonal cell populations in the PB were detected in 11 (30%) of 37 examined MM patients, but in none of the patients with MGUS or solitary plasmacytoma of bone. PB involvement was associated with progressive disease. Circulating monoclonal cells were significantly associated with higher M-protein levels (p 0.05). Thus, circulating clonal precursor cells are encountered more frequently in active MM.  相似文献   
998.
We examined the effect of interruption of pulmonary arterial flow and inadequate ventilation on the development of pulmonary infarction in rats. Pulmonary arterial flow was blocked by the injection of agar into the inferior vena cava and inadequate ventilation was produced by obstructing the left main bronchus with a polypropylene tip. Histological and angiographic examination of the lung demonstrated that: pulmonary artery embolism alone does not induce pulmonary infarction; obstruction of a bronchus does not induce significant changes, but that pulmonary infarction develops when pulmonary artery embolism and obstruction of a bronchus occur simultaneously. It has been thought that pulmonary infarction is caused by acute obstruction of a pulmonary artery, however, the alveolar walls are supplied with oxygen by both the pulmonary circulation and by ventilation. Interruption of pulmonary arterial flow alone is probably not sufficient to induce pulmonary infarction, which is probably caused by deficiency of oxygen supply to the alveolar walls by a synergy between interruption of pulmonary arterial flow and inadequate ventilation.  相似文献   
999.
1000.
本研究应用电镜CMP酶细胞化学和心钠素免疫电镜胶体金,分别标记人心房肌细胞中初级溶酶体和心钠素,进行鉴别定位观察和定量分析。心钠素颗粒数量居多,占78.7~79.3%,大小均一,直径0.20±0.05μm(x±s),分布于整个细胞质内,多成簇,尤以肌膜下,核极区多见。而溶酶体大小不一,直径0.30±0.19μm(x±s),显著大于心钠素颗粒(P<0.001),一般在核极区成簇分布,也见肌原纤维之间和肌膜下单个散在分布。  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