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   10081篇
  免费   447篇
  国内免费   56篇
耳鼻咽喉   59篇
儿科学   175篇
妇产科学   98篇
基础医学   1236篇
口腔科学   298篇
临床医学   647篇
内科学   2989篇
皮肤病学   218篇
神经病学   698篇
特种医学   360篇
外科学   1670篇
综合类   25篇
预防医学   325篇
眼科学   121篇
药学   731篇
中国医学   14篇
肿瘤学   920篇
  2023年   53篇
  2022年   108篇
  2021年   168篇
  2020年   114篇
  2019年   134篇
  2018年   172篇
  2017年   144篇
  2016年   163篇
  2015年   184篇
  2014年   198篇
  2013年   266篇
  2012年   428篇
  2011年   495篇
  2010年   281篇
  2009年   234篇
  2008年   475篇
  2007年   474篇
  2006年   437篇
  2005年   465篇
  2004年   470篇
  2003年   408篇
  2002年   447篇
  2001年   311篇
  2000年   306篇
  1999年   268篇
  1998年   110篇
  1997年   92篇
  1996年   98篇
  1995年   80篇
  1994年   87篇
  1993年   90篇
  1992年   275篇
  1991年   243篇
  1990年   198篇
  1989年   247篇
  1988年   212篇
  1987年   221篇
  1986年   218篇
  1985年   190篇
  1984年   120篇
  1983年   95篇
  1982年   48篇
  1979年   82篇
  1978年   53篇
  1977年   49篇
  1975年   44篇
  1972年   44篇
  1971年   48篇
  1969年   46篇
  1968年   46篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
IgA immune complexes and polymeric IgA are presumed to play important roles in the development and progression of IgA nephropathy. Complex-forming glycoprotein heterogenous in charge (protein HC), being inhibitors of neutrophilic chemotaxis, has been reported as binding to IgA. As a working hypothesis it was assumed that complexes of protein HC and IgA are present in glomeruli from IgA nephropathy patient in stable state. In this study, we examined the glomerular deposition of protein HC in 40 patients with IgA nephropathy and in 10 patients with non-IgA nephropathy. We used highly specific antibody against protein HC, that does not cross-react with alpha-1-microglobulin. An immunofluorescent study revealed that 10 out of the 40 patients (25%) showed an intensity of 1+, 16 (40%) showed weak positive (+/-), and the other 14 (35%) were negative. There was no deposition of protein HC in non-IgA nephropathy patients. Histopathological analysis demonstrated a significant correlation between the intensity of glomerular-deposited protein HC and pathological activity (p less than 0.005); the latter was defined as having either crescents in more than 15% of the remaining glomeruli (excluding global sclerotic glomeruli), or segmental necrosis or sclerosis in more than 30% of the remaining glomeruli. A significant correlation was observed between pathological activity and the intensity of deposited IgG, IgA and IgM (p = 0.01), and lambda chain (p less than 0.005). Considering anti-inflammatory activity of protein HC, these results suggest that protein HC cannot protect sufficiently acute inflammation or tissue damages due to co-deposited IgG and IgM and/or other factors.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
42.
J Hamada  H Seto  M Miura  J Kuratsu  Y Ushio 《Neurosurgery》1990,27(4):647-649
A rare case of suprasellar pituitary adenoma arising from the pars tuberalis in a 53-year-old woman is presented. The tumor was located exclusively above the diaphragma sellae, and no invasion into the sella turcica was noted.  相似文献   
43.
Combined large cell neuroendocrine carcinoma   总被引:1,自引:0,他引:1  
We report a case of combined large cell neuroendocrine carcinoma. A 78-year-old man with vertigo was referred to our hospital where chest X-ray revealed a tumor shadow in the right lung. A transbronchial lung biopsy specimen verified a diagnosis of non-small cell lung carcinoma (cT1N0M0). Right lower lobectomy with mediastinal lymph node dissection (#7,8,9) was performed. A postoperative histological diagnosis was combined large cell neuroendocrine carcinoma of a component of squamous cell carcinoma [pT4 (pm) N2M0]. The patient received concurrent chemoradiotherapy due to upper mediastinal lymph node metastasis 4 months after surgery. The chemoradiotherapy well responded and the patient remains well 9 months after surgery.  相似文献   
44.
45.
Mechanism of methylmercury cytotoxicity   总被引:2,自引:0,他引:2  
Although a large number of epidemiological, clinical, and pathological studies on methylmercury intoxication have been published, these investigations have not been able to elucidate the detailed mechanisms by which the metal alkyl causes a wide variety of biological dysfunctions. Thus, the cultured cells which are free from the influence of whole body complexities, such as absorption, distribution, metabolism, etc., which complicate the interpretation of in vivo experimental results, attract the attention of many scientists who are interested in clarifying the mode of toxic action of methylmercury. The aim of this article is to review the recent studies on the toxicity of methylmercury at the cellular level and to outline the mechanisms which have been proposed to be responsible for cell injuries.  相似文献   
46.
Y Takahashi  T Miura 《Toxicology》1989,56(3):253-262
Male Jcl:Wistar rats were exposed continuously to 0.2 ppm ozone (O3) and 4 ppm nitrogen dioxide (NO2), alone and in combination, for 1 and 2 months to examine the effects of combined gas on the xenobiotic metabolizing systems of lung microsomes. The cytochrome P-450 content increased to 200% and 253% of the control values during 2-month exposures to O3, while it was not increased by NO2 exposures. Addition of NO2 to O3 reduced the increased level of cytochrome P-450 to 179% and 178% of the control values. The activities of cytochrome P-450-dependent monooxygenase, benzo[a]pyrene hydroxylase and 7-ethoxycoumarin O-deethylase were changed in the same fashion by exposures to NO2 and O3. The 7-ethoxycoumarin O-deethylase activity was increased to 147% and 142% of the control values by O3 exposure, whereas it was decreased to 71% and 75% of the control values by NO2 exposures. This activity was decreased to 124% and 97% of the control values by combination of O3 with NO2 after 1 and 2 months, respectively. Similarly, the benzo[a]pyrene hydroxylase activity was increased to 157% and 153% of the control values during O3 exposures, while it was not changed by NO2 exposures. Addition of NO2 to O3 reduced the activity to 140% and 115% of the control values after 1 and 2 months, respectively. The alteration of coumarin hydroxylase activity was different from those of others. This activity decreased to 44% and 29% of the control values after 1- and 2-month exposures to NO2, respectively, and was also decreased by O3 exposures. However, the magnitude of decrease was not reinforced by combination of NO2 with O3. These results indicate that an increased level of xenobiotic metabolizing activity produced by O3 exposures is lowered by combination with NO2. These phenomena may be antagonistic effects of these gases on the xenobiotic metabolizing systems of lung microsomes.  相似文献   
47.
48.
We report a metastatic pulmonary tumor resected by video-assisted thoracoscopic surgery. A 63-year-old female was found to have four nodules of hepatocellular carcinoma (HCC) in January 1991; after non-surgical treatment, the tumors had become necrotic. In June 1992, a new HCC nodule was found. After infusion chemotherapy, it became necrotic. In September 1993, a solitary lung tumor, 2.4 cm in diameter, appeared at the periphery of the right lung. Because the tumor was considered to be a metastatic HCC rather than a primary lung cancer, it was removed by thoracoscopic wedge resection. Although whether metastasectomy contributes to prolongation of survival is still controversial, thoracoscopic pulmonary resection may be indicated for solitary peripheral metastasis, if the primary HCC is well controlled by multidisciplinary treatment.  相似文献   
49.
An enzyme-linked immunosorbent assay (ELISA) system for the quantitation of human monocytic colony-stimulating factor (hM-CSF) was established, which was based on the "dual antibody immunometric sandwich" principle using horse and rabbit polyvalent antibodies against human urinary colony-stimulating factor (CSF-HU). The minimal detectable level of hM-CSF was 10 U/mL, and the assays showed good reproducibility. As measured by this method, the average serum hM-CSF level of 20 normal adults was 540 +/- 110 U/mL (range, 300 to 800 U/mL). The peak of hM-CSF measured by ELISA was identical to that measured by bioassay when semipurified CSF-HU was fractionated by reversed-phase high performance liquid chromatography (HPLC). This method detected two types of hM-CSF, which had approximate molecular weights of 85 Kd (CSF-HU) and 45 Kd in human serum and urine; the ratio of 85:45 Kd was very high in serum and the amounts of the two types were nearly equal in urine. After anticancer chemotherapy, the serum hM- CSF level of one half of the patients with hematological malignancy was elevated according to the reduction in neutrophil number, while it was almost in the normal range in the other half of the patients, indicating the possibility that anticancer chemotherapy damaged the hM- CSF-producing cells. This ELISA method may be useful for monitoring the serum hM-CSF level after anticancer chemotherapy.  相似文献   
50.
Summary Four patients with dural arteriovenous malformation (AVMs) draining into the cavernous sinus, who presented ophthalmic manifestations, were studied by magnetic resonance (MR) imaging. In all patients signal decrease in the involved cavernous sinus was demonstrated in coronal spinecho (SE) imaging. It is attributable to rapid venous flow in the sinus, and this high velocity signal loss is a fairly pathognomonic finding in this condition. We stress the validity of MR imaging in the primary diagnosis of dural AVMs with ophthalmic symptoms.  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