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   52428篇
  免费   4193篇
  国内免费   1908篇
耳鼻咽喉   614篇
儿科学   655篇
妇产科学   562篇
基础医学   7065篇
口腔科学   835篇
临床医学   5926篇
内科学   7556篇
皮肤病学   1214篇
神经病学   3202篇
特种医学   2249篇
外国民族医学   14篇
外科学   4885篇
综合类   6310篇
现状与发展   9篇
一般理论   11篇
预防医学   3793篇
眼科学   1377篇
药学   5803篇
  60篇
中国医学   2455篇
肿瘤学   3934篇
  2024年   160篇
  2023年   705篇
  2022年   2080篇
  2021年   2827篇
  2020年   1893篇
  2019年   1612篇
  2018年   1779篇
  2017年   1656篇
  2016年   1743篇
  2015年   2591篇
  2014年   3176篇
  2013年   3318篇
  2012年   4798篇
  2011年   4920篇
  2010年   3041篇
  2009年   2516篇
  2008年   3140篇
  2007年   2840篇
  2006年   2436篇
  2005年   2218篇
  2004年   1633篇
  2003年   1368篇
  2002年   1062篇
  2001年   850篇
  2000年   869篇
  1999年   674篇
  1998年   310篇
  1997年   266篇
  1996年   192篇
  1995年   195篇
  1994年   161篇
  1993年   117篇
  1992年   195篇
  1991年   210篇
  1990年   159篇
  1989年   123篇
  1988年   99篇
  1987年   89篇
  1986年   77篇
  1985年   59篇
  1984年   36篇
  1983年   40篇
  1982年   33篇
  1981年   23篇
  1980年   23篇
  1979年   36篇
  1978年   22篇
  1976年   17篇
  1974年   21篇
  1971年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
2.
Background/purpose: Vitiligo and nevus depigmentosus (ND) present similar hypopigmented macules with significantly different prognoses. Although the distinction between the two diseases is important, differential diagnosis relies on medical history and physical examination, which is far from decisive in some cases. The Mexameter® is an objective skin color-measuring device, and has been reported to provide a reproducible and sensitive means of quantifying small skin color differences. In this study, we investigated the usefulness of a Mexameter® for discriminating these diseases.
Methods: A selection of 202 hypopigmented skin lesions (182 from vitiligo and 20 from ND) were the objects of this study. Using a Mexameter, MIs were obtained from lesions and symmetrically located control skin. RMIs, ratios of the MIs of lesional skins to control skins, were calculated.
Results: The mean MIs and RMIs were significantly different for vitiligo and ND. The mean RMI of ND lesions was 74±13, which was significantly higher than that of vitiligo lesions (50±24). No ND lesion had an RMI of <50%.
Conclusion: This study shows that the Mexameter®, an objective pigment-measuring device, can be used to achieve a more accurate diagnosis of hypopigmentary disorders, and that the relative melanin index (RMI), which represents the relative pigment levels, might be a more effective parameter than the melanin index (MI) itself for comparing pigmentation differences.  相似文献   
3.
Pituitary abscess is a rare and potentially lethal condition. Pituitary abscess in a pregnant woman has not been previously described. A 38-year-old pregnant woman (34 weeks gestation) with a pituitary mass complained of a progressive headache and sudden visual impairment. She was afebrile and had no inflammatory symptoms on admission. On MRI, the preoperative diagnosis was pituitary adenoma with sphenoid sinusitis. She underwent an uncomplicated transsphenoidal procedure for removal of the pituitary mass. The next day, labor commenced and a healthy preterm baby was delivered. Pathologic examination of the intrasellar mass showed polymorphonuclear cells, debris and no tumor cells. The sellar contents were cultured and Streptococcus viridans was grown. To our knowledge this is the first case of pituitary abscess reported during pregnancy. Although the patient was pregnant, the transsphenoidal approach was safe for the mother and the fetus. Surgical drainage and antibiotic therapy are required for the definitive treatment of this condition.  相似文献   
4.
With the introduction of more potent immunosuppressive agents, rejection has decreased in simultaneous pancreas/kidney transplant (SPK) recipients. However, as a consequence, opportunistic infections have increased. The purpose of this report is to outline the course of SPK patients who developed polyomavirus-associated nephropathy (PVAN). A retrospective review of 146 consecutive SPK recipients from January 1, 1996 to December 31, 2002 was performed. Immunosuppression, rejection and development of PVAN were reviewed. Nine patients were identified. All received induction with either OKT3 or thymoglobulin. Immunosuppression included tacrolimus/cyclosporine, MMF/azathioprine and sirolimus/prednisone. Two patients were treated for kidney rejection prior to the diagnosis of PVAN. Time to diagnosis was an average of 359.3 days post-transplantation. Immunosuppression was decreased but five ultimately lost function. However, none developed pancreatic abnormalities as demonstrated by normal glucose and amylase. Two underwent renal retransplantation after PVAN diagnosis and both have normal kidney function. PVAN was the leading cause of renal loss in SPK patients in the first 2 years after transplantation and is a serious concern for SPK recipients. The pancreas, however, is spared from evidence of infection, and no pancreatic rejection occurred when immunosuppression was decreased.  相似文献   
5.
6.
7.
Nineteen cases of mid-trimester pregnancy were terminated using prostaglandin E2 gel applied intracervically. In this prospective study, 42% were primipara with gestational age at the time of abortion between 16 and 28 weeks. The induction to abortion time was 19.65 +/- 10.37 h with a success rate of 89%. The average number of applications was 1.8 times (range 1-3 times) and the average dosage of prostaglandin required was 5.5 mg (range 3-9 mg). The complications were minimal except retained placenta in 42% of cases. Prostaglandin E2 in form of gel applied intracervically is an effective alternative to the commonly used hypertonic saline or, more recently, to prostaglandin analogues for termination of pregnancy in the second trimester.  相似文献   
8.
BACKGROUND: To adequately address the complex health needs of young people, their access to services, and the quality of services received, must be improved. AIMS: To explore the barriers to service provision for young people and to identify the training needs of primary healthcare service providers in New South Wales (NSW), Australia. DESIGN OF STUDY: A cross-sectional, qualitative study of the perspectives of a range of health service providers. SETTING: A range of primary healthcare organisations across NSW. METHODS: Samples of general practitioners (GPs), youth health workers, youth health coordinators, and community health centre staff were drawn from urban and rural clusters across NSW. Focus groups and interviews were used to identify barriers to service provision and the training needs of service providers. Data were tape recorded, transcribed, and analysed. RESULTS: Barriers to service provision among GPs and community health centre staff included inadequate time, flexibility, skills, and confidence in working with young people, and poor linkages with other relevant services. Training needs included better knowledge of and skills in adolescent health requirements, working with adolescents, and working with other services. Barriers to service provision for youth health workers and coordinators included lack of financial resources and infrastructure. There were few linkages between groups of service providers. CONCLUSION: Models of service provision that allow stronger linkages between service providers, sufficient time for consultation with young people, adequate training and support of health professionals, and flexibility of service provision, including outreach, should be explored and evaluated.  相似文献   
9.
A magnetic resonance imaging study of putamen nuclei in major depression.   总被引:7,自引:0,他引:7  
The basal ganglia are recognized as putative mediators of certain cognitive and behavioral symptoms of major depression. Moreover, patients with basal ganglia lesions have repeatedly exhibited significant affective symptomatology, including apathy, depressive mood, and psychosis. Using high resolution, axial T2 intermediate magnetic resonance images, and a systematic sampling stereologic method, we assessed putamen nuclei volumes in 41 patients with major depression (DSM-III) and 44 healthy volunteer controls of similar age. Depressed patients had significantly smaller putamen nuclei compared with controls. Age was negatively correlated with putamen size in both groups. These results are the first demonstration of diminished putamen volumes in depression and further support a role for basal ganglia structures in the etiopathogenesis of depression.  相似文献   
10.
Eight cases of malignant and 12 0f benign Bren- ner tumor are reported, patient ages ranged 31 69 and 39-53 years. The malignant tumor was bilateral in 6 0f 8 cases, and the benign in l of 12. The greatest diameter of the malignant tumors averaged around 11 cm, and the benign 10. Six of the malignant Brenner tumor patients died, one was lost to follow up, and one survived for 10 years. Pathologic and microscopic findings were pre- sented in some detail. Based on the analysis of the association between the histologic features and type of Mullerian epithelium, we believe that the so called Brenner tumor is in effect a tumor arising from the Mullerian epithelium with a tendency to differentiate into vaginocervical type epithelium.  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