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   18722篇
  免费   952篇
  国内免费   127篇
耳鼻咽喉   200篇
儿科学   309篇
妇产科学   167篇
基础医学   2141篇
口腔科学   387篇
临床医学   1158篇
内科学   4962篇
皮肤病学   319篇
神经病学   1125篇
特种医学   761篇
外科学   3683篇
综合类   101篇
预防医学   534篇
眼科学   324篇
药学   1100篇
中国医学   76篇
肿瘤学   2454篇
  2023年   105篇
  2022年   199篇
  2021年   448篇
  2020年   252篇
  2019年   339篇
  2018年   431篇
  2017年   338篇
  2016年   440篇
  2015年   457篇
  2014年   552篇
  2013年   627篇
  2012年   1003篇
  2011年   1182篇
  2010年   671篇
  2009年   516篇
  2008年   992篇
  2007年   1112篇
  2006年   1043篇
  2005年   1067篇
  2004年   1065篇
  2003年   1030篇
  2002年   1006篇
  2001年   452篇
  2000年   412篇
  1999年   407篇
  1998年   238篇
  1997年   201篇
  1996年   183篇
  1995年   151篇
  1994年   116篇
  1993年   132篇
  1992年   245篇
  1991年   209篇
  1990年   210篇
  1989年   195篇
  1988年   183篇
  1987年   166篇
  1986年   156篇
  1985年   171篇
  1984年   113篇
  1983年   117篇
  1982年   60篇
  1979年   80篇
  1978年   67篇
  1977年   52篇
  1975年   47篇
  1974年   50篇
  1973年   53篇
  1971年   49篇
  1969年   46篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Zhenxuanyin [symbol: see text] is composed of pure Chinese medicinal herbs, such as gastrodia tuber, poria cocos, ligusticum wallichii etc. 4-verssel occlusion (4VO) model rats were reperfused after 30 minutes' complete occlusion, and Zhenxuanyin was administered 3 times a day. 24 hours later, 123I-IMP uptake in the brain was evaluated as an index of cerebral blood flow (CBF). The results show that Zhenxuanyin (0.03 g/kg, 0.3 g/kg, 1 g/kg, or 3 g/kg a day) can greatly improve the blood flow in the main cerebral regions, and 0.3 g/kg can increase cerebral blood flow (CBF) to the normal level.  相似文献   
52.
In the medical field, Korotkoff sounds have been explained as sounds generated by the disturbed blood flow in the artery. However, in the biomechanics field, Korotkoff sounds are considered to be produced and/or modified by the self-excited oscillation of a collapsed artery. The self-excited oscillation is an oscillation of the arterial wall. In addition, it is influenced by the nonlinear pressure–flow relationships in the artery and the arterial compliance. In this paper, we proposed an arterial-compliance-measuring method, using Korotkoff sounds. We constructed a circulatory simulator with a brachial model that mimics the physiological circulation, because in vivo resolution of nonlinear pressure–flow relationships is very difficult. The simulator was utilized to generate artificial Korotkoff sounds similar to those in auscultation in the brachial model. Additionally, we prepared latex tubes as artificial brachial arteries. In the experiment, we investigated the relationship between the self-excited oscillation and Korotkoff sounds by the distinguishing its frequency characteristics. The frequency of the sounds was changed by the variation of the tube compliance. As a result, we have found that the changes of the sounds largely depended on the difference of the tube compliance in this simulator. In conclusion, Korotkoff sounds contain useful information for predicting brachial arterial compliance. These experiments indicate the effectiveness of noninvasive measurement for brachial arterial compliance using Korotkoff sounds.  相似文献   
53.
The purpose of this study was to determine the relationship between segmental hyperintensity of the liver on T1-weighted images and segmental cholestasis in patients with obstructive jaundice. T1-weighted and T2-weighted MR images were obtained of 73 patients with obstructive jaundice caused by various diseases. Fat-suppressed T1-weighted images were also obtained of 10 patients. Eleven patients with segmental intra-hepatic bile duct dilatation (cholestasis) showed segmental hyperintensity on T1-weighted images and/or fat-suppressed T1-weighted images and no signal intensity difference on T2-weighted images. Sixty-two patients with widespread intrahepatic bile duct dilatation showed no intensity difference on T1-weighted and T2-weighted images (P < .01). Segmental hyperintensity on T1-weighted images was correlated with intrahepatic cholestasis.  相似文献   
54.
Kimura's disease is a rare disorder that involves regional lymph nodes and the major salivary glands, which become infiltrated by eosinophils and lymphocytes. Renal lesions associated with Kimura's disease are rare. We describe the case of a 60-year-old Japanese woman who first noted a nodular mass in a salivary gland. As the nodule grew, nephrotic syndrome and heart failure developed. A biopsy of the nodule revealed Kimura's disease, and surgical excision was performed. After the operation, the heart failure and nephrotic syndrome, which were diagnosed as minimal change disease on renal biopsy, improved rapidly without steroid therapy. Four months later, the nephrotic syndrome recurred without recurrence of Kimura's disease. The patient showed marked improvement during prednisolone therapy (40 mg/d) and was in complete remission 4 weeks after the initiation of steroid therapy. This case shows that surgical excision and prednisolone therapy are useful for nephrotic syndrome associated with Kimura's disease.  相似文献   
55.
A 74-year-old man with combined valvular disease with a recent cerebral infarction was admitted. While undergoing thorough examination for valvular disease, absent right superior vena cava (RSVC) and persistent left superior vena cava (PLSVC) were recognized. Chest X-ray film suggested a right arch protrusion, and CT and venogram confirmed the diagnosis. During surgery, replacement of the mitral and aortic valves and annuloplasty of the tricuspid valve were performed. A blood draining cannula was inserted in retrograde fashion from the coronary sinus into the PLSVC, without any difficulties in the tricuspid valve repair. Due to bradycardic atrial fibrillation, we believed that it would be difficult to insert an endocardial electrode postoperatively, hence myocardial electrode was placed in the right ventricular wall. Absent RSVC combined with PLSVC is very rare, and a patient who underwent combined valve surgery with this rare anatomical abnormality is herein presented.  相似文献   
56.
PURPOSE: The association of BRCA2 polymorphisms at codon 372 [Asn (N)/His (H)]and codon 784 [Met (M)/Val (V)] with breast cancer risk was evaluated in Japanese women. In addition, the prognostic significance of these polymorphisms was studied in breast cancer patients. EXPERIMENTAL DESIGN: A case-control study was conducted to examine the association of the BRCA2 N/H372 polymorphism and M/V 784 polymorphism with breast cancer risk (cases = 149, controls = 154). The prognostic significance of these polymorphisms was evaluated in 139 patients with primary breast cancer. RESULTS: No significant association was observed between the N/H372 polymorphism and breast cancer risk. In contrast, a significant increase in breast cancer risk (odds ratio, 2.03; 95% confidence interval, 1.07-3.87) was observed in carriers of the variant allele (V784) of the M/V784 polymorphism as compared with noncarriers after adjustment for the classical risk factors, age, family history, parity, body mass index, and so forth. Among breast cancer patients, various clinicopathological parameters including menopausal status, tumor size, lymph node status, histological grade, and estrogen-receptor status were not significantly different between the carriers and noncarriers of the variant allele with regard to both N/H372 and M/V784 polymorphisms. The N/H 372 polymorphism was not significantly associated with patient prognosis. On the other hand, breast cancer patients carrying the variant allele of M/V784 polymorphism showed a significantly (P = 0.014) lower 3-year disease-free survival rate (63%) than noncarriers (92%). Multivariate analysis has revealed that the M/V784 polymorphism is a significant prognostic factor, being independent of the other conventional prognostic factors such as lymph node status and estrogen receptor status. CONCLUSION: These results suggest that the M/V784 polymorphism, but not the N/H372 polymorphism, would be useful in the selection of women at high risk for developing breast cancer and would also serve as a clinically useful prognostic factor in breast cancer patients.  相似文献   
57.
The present study was designed to examine the selectivity of 3H-CGP-12177 (4-(3-t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazole-2-one hydrochloride) for beta 1- and beta 2-adrenergic receptors by the Scatchard and the displacement analysis. The plots of specific binding obtained from the Scatchard analysis using 3H-CGP12177 for the rat myocardium membrane were uniphasic when the non-specific binding was determined by the use of 10 microM I-propranolol, and the Kd and Bmax values were 408.53 +/- 67.20 pM and 12.27 +/- 0.83 fmoles/mg protein, respectively. On the other hand, two binding sites were observed in the displacement curve when I-metoprolol was used as a competitor. The existence of these two binding sites implied the selectivity of 3H-CGP12177 to beta-adrenoceptors because 3H-CGP12177 was 1.8-fold more selective towards beta 1-adrenoceptors than beta 2-adrenoceptors. In addition, these two binding sites could be regarded as beta 1- and beta 2-adrenergic receptors from the evaluation of the binding characteristics beta-adrenoceptors by the displacement analysis using beta-selective antagonists. Thus, 3H-CGP12177, a hydrophilic radioligand, was useful for the binding assay of beta-adrenoceptors in rat myocardial membranes.  相似文献   
58.
The effectiveness of Tc-99m bleomycin (BLM) and Tc(V)-99m DMSA are compared with that of Ga-67 citrate, which is currently the most widely used agent. In four patients with lipomatous tumors, the clinical significance of tumor imaging with each of these three agents is discussed and compared. Results indicate that both Tc-99m BLM and Tc(V)-99m DMSA are superior in detecting the extension or localization of liposarcomas.  相似文献   
59.
60.
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