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   8655篇
  免费   2678篇
  国内免费   38篇
耳鼻咽喉   204篇
儿科学   231篇
妇产科学   241篇
基础医学   383篇
口腔科学   83篇
临床医学   1279篇
内科学   2343篇
皮肤病学   451篇
神经病学   773篇
特种医学   341篇
外科学   2636篇
综合类   101篇
预防医学   626篇
眼科学   627篇
药学   229篇
中国医学   15篇
肿瘤学   808篇
  2024年   87篇
  2023年   691篇
  2022年   127篇
  2021年   340篇
  2020年   426篇
  2019年   201篇
  2018年   727篇
  2017年   768篇
  2016年   672篇
  2015年   620篇
  2014年   853篇
  2013年   799篇
  2012年   496篇
  2011年   415篇
  2010年   583篇
  2009年   737篇
  2008年   386篇
  2007年   244篇
  2006年   292篇
  2005年   187篇
  2004年   178篇
  2003年   130篇
  2002年   143篇
  2001年   149篇
  2000年   86篇
  1999年   113篇
  1998年   109篇
  1997年   99篇
  1996年   71篇
  1995年   67篇
  1994年   50篇
  1993年   49篇
  1992年   57篇
  1991年   52篇
  1990年   36篇
  1989年   33篇
  1988年   36篇
  1987年   28篇
  1986年   20篇
  1985年   26篇
  1984年   13篇
  1983年   12篇
  1982年   19篇
  1981年   11篇
  1980年   9篇
  1979年   15篇
  1978年   16篇
  1977年   16篇
  1976年   10篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Impaired absorption of sodium (Na+) and water is a major factor in the pathogenesis of diarrhoea in ulcerative colitis (UC). Electrogenic Na+ absorption, present mainly in human distal colon and rectum, is defective in UC, but the molecular basis for this is unclear. The effect of UC on the expression of apical Na+ channels (ENaC) and basolateral Na+, K+-ATPase, the critical determinants of electrogenic Na+ transport, was therefore investigated in this study. Sigmoid colonic and/or proximal rectal mucosal biopsies were obtained from patients with mild to moderate UC, and patients with functional abdominal pain (controls). ENaC subunit expression was studied by immunohistochemistry, western blot analysis, and in situ hybridization, and Na+, K+-ATPase isoform expression was studied by immunohistochemistry, western blotting, and northern blot analysis. UC was associated with substantial decreases in the expression of the ENaC beta- and gamma-subunit proteins and mRNAs, whereas the decrease in ENaC alpha-subunit protein detected by immunolocalization was less marked. The levels of expression of Na+, K+-ATPase alpha1- and beta1-isoform proteins were also lower in UC patients than in controls, although there were no differences in Na+, K+-ATPase alpha1- and beta1-isoform mRNA levels between the two groups. Taken together, these results show that UC results mainly in decreased expression of the apical ENaC beta- and gamma-subunits, as well as the basolateral Na+, K+-ATPase alpha1- and beta1-isoforms. In conclusion, these changes provide a basis for the low/negligible levels of electrogenic Na+ absorption seen in the distal colon and rectum of UC patients, which contribute to the pathogenesis of diarrhoea in this disease.  相似文献   
62.
63.
Infertility is a major health issue affecting over 48.5 million couples around the world, with the male factor accounting for about 50% of the cases. The conventional semen analysis recommended by the World Health Organization (WHO) is the cornerstone in the evaluation of male fertility status. It includes macroscopic and microscopic evaluation of the ejaculate, which reflects the production of spermatozoa in the testes, the patency of the duct system and the glandular secretory activity. Evaluation of seminal fructose, sperm vitality and leucocytes (Endtz test) are useful adjuncts to semen analysis that provide information on specific clinical conditions. Though several computer-assisted sperm analysis (CASA) systems have been developed, conventional methods for semen analysis are still widely accepted in clinical practice. This review summarises the conventional techniques used in routine semen analysis and their diagnostic value in clinical andrology.  相似文献   
64.
Varicocele is one of the major causes of male infertility and has a negative impact on spermatogenesis. The conventional semen analysis does not reveal the underlying subcellular mechanisms associated with defects in spermatozoa. Proteomics and bioinformatics analysis can be used to identify the molecular aetiologies associated with poor semen quality in varicocele patients. Mitochondrial dysfunction has been identified as the main factor affecting normal physiological functions of spermatozoa. This article discusses the proteomic studies of spermatozoa and seminal plasma in varicocele patients. Proteomics can identify potential spermatozoa and seminal plasma biomarkers in varicocele-mediated male infertility. In future, these protein biomarkers can be useful in the development of noninvasive diagnostic and therapeutic strategies for varicocele patients.  相似文献   
65.
A 46-year-old male presented with breathlessness for a few months. He had been operated twice for liver hydatid cysts and once for right pulmonary hydatid cysts at other hospitals. Now he was found to have one hydatid cyst in the upper lobe of the left lung and multiple hydatid cysts adjoining left heart border. On computed tomography (CT) scan chest and echocardiography, it was difficult to ascertain whether these cysts were pulmonary or intrapericardial. Left ventricular ejection fraction (LVEF) was 25%. Enzyme-linked immunosorbent assay (ELISA) was positive for hydatid. Left posterolateral thoracotomy revealed dead hydatid cyst in upper lobe of the lung that was removed. Infected mother hydatid cyst was encountered inside pericardial sac. Scores of daughter hydatid cysts, varying in size from 1 to 30 mm, were scooped out intact from the pericardial cavity. There was significant improvement in cardiac activity, once the tamponade effect of hydatid cyst was removed. Pericardium was about 1 cm thick with lot of purulent and necrotic slough. To prevent future constrictive pericarditis, subtotal pericardiectomy was done. Intrapericardial hydatid cyst should be kept in mind whenever it obscures the heart border and patient has features of cardiac tamponade. Early surgical intervention may be required in these cases.  相似文献   
66.
67.
BackgroundTardy ulnar nerve palsy is the development of late onset ulnar nerve dysfunction and is usually treated by open anterior transposition of ulnar nerve. Open technique is done using a longitudinal incision about 6–8 inch. in length with chances of development of medial antebrachial cutaneous nerve neuromas.PurposeIn this study, we describe the technique of Endoscopic Anterior Transposition of Ulnar Nerve (EATUN procedure) to treat tardy ulnar nerve palsy and analyze the results.MethodsSeven patients diagnosed to have tardy ulnar nerve palsy was treated by EATUN. The humerus-elbow-wrist angle (HEW), pre- and post-operative intrinsic muscle power and sensory assessment, Dellon scores, and the Q-DASH was analyzed.ResultsThe minimum follow-up was 12 months (Mean 27.4 months, Range 12–36 months). Improvement in Dellon and Q-DASH scores following EATUN procedure was statistically significant. There was objective improvement of intrinsic muscle power and sensation on follow-up, though not statistically significant. No instance of neuroma of the medial cutaneous nerve of forearm was noted.ConclusionsThe endoscopic anterior transposition of the ulnar nerve is a good option in surgical management of tardy ulnar nerve palsy.Level of evidenceTherapeutic Level IV.Supplementary InformationThe online version contains supplementary material available at 10.1007/s43465-021-00366-w.  相似文献   
68.
Breast fat necrosis (BFN) is usually a benign inflammatory response to breast trauma. However, an extremely rare cause of fat necrosis is calciphylaxis, a calcification of small- and medium-sized arteries causing thrombosis and ischemia. It is classified into (A) uremic (B) nonuremic-induced calciphylaxis. Calciphylaxis has been reported to be encountered in different parts of the body. However, to the best of our knowledge there is only one case in the English literature of BFN 2ry to warfarin-induced calciphylaxis. We report a 65-year-old female, known case of atrial fibrillation on warfarin, presented with a left breast mass of 4-month duration. The mass was painful and progressively enlarging. Examination of the left breast showed 7 × 4 cm mass, spanning from 10-2 o'clock, free from surrounding structures, with preserved overlying skin. However, the mass was not visualized on mammogram. Ultrasound showed a left breast lobulated hypoechoic mass containing a hyperechoic component. Biopsy showed fat necrosis. After 1 month, she presented with ulceration of the overlying skin. After wide local excision, histopathology demonstrated a calciphylaxis-induced fat necrosis. Considering the patient's background, the diagnosis was BFN secondary to warfarin-induced calciphylaxis. Hence, the warfarin was shifted to Rivaroxaban, 6 months follow-up showed no evidence of recurrence. In conclusion, the rarity of nonuremic calciphylaxis is reflected on the delay of diagnosis in some of the reported cases and the lack of grading system used to guide the management of such difficult wounds. However, keeping a high index of suspicion is important whenever such wounds are encountered with presence of risk factors other than end-stage kidney disease.  相似文献   
69.
Rhabdomyosarcoma (RMS) is a common malignancy in children, but embryonal rhabdomyosarcoma (ERMS) deposits rarely occur in the breast in adults. Therefore, little is known about magnetic resonance imaging (MRI) features of breast metastases from RMS, especially the embryonal type. We reported a case of a 22-year-old woman who was diagnosed with ERMS at left foot 2 years ago and accepted operation and chemotherapy. She was confirmed to have breast metastases from the left foot. Successive imaging examinations were performed 3 months apart. Breast ultrasound indicated a benign lesion, and further examination did not reveal any bone metastases. However, predominant restricted diffusion and rim contrast enhancement on MRI combined with the patient's medical history suggested a malignancy of BI-RADS 5. After 3 months, breast ultrasound revealed masses detected last time became larger and lobulated. In addition, internal heterogeneous intensity and rim contrast enhancement with restricted diffusion were revealed on MRI. We speculated that typical MRI findings of breast metastases from RMS may include iso- to hypointensity on T1WI, heterogeneous hyperintensity on T2WI, and circular enhancement with restricted diffusion. Moreover, mild peritumoral edema, rapid expansion of necrosis, and ascending time-intensity curve detected on MRI may be features of the ERMS type.  相似文献   
70.
Self-care enables patients in improving quality of life and reducing hospital admissions. Research explored the experiences of patients about breathlessness, sleep problems and complication management in chronic obstructive pulmonary disease (COPD). However, the self-care experiences and the role of the family in self-care are underexplored. This study aimed to understand the self-care experiences of patients with COPD and explore the role of the family in self-care. An interpretive phenomenological inquiry was used, and 13 patients were interviewed in 2019 from two hospitals in Pakistan. The inclusion criteria were patients above 30 years of age at any stage of COPD, who received a confirmed diagnosis of COPD and were receiving the treatment, and engaged in self-care at their homes or communities. The interviews lasted for 35–60 min. Ricoeur's interpretation theory was used for data analysis comprising steps explanation, naive understanding and in-depth understanding. Self-care emerged as a complex individual and familial endeavour affected by personal, social and economic factors. Poverty was one of the core determinants of self-care. Patients emphasised the spiritual, cultural and traditional approaches to self-care. Future research is warranted to develop better understanding of spiritual and cultural self-care and how these dimensions of self-care affect patients’ self-care behaviours.  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