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   1696940篇
  免费   123784篇
  国内免费   3795篇
耳鼻咽喉   21741篇
儿科学   55648篇
妇产科学   46166篇
基础医学   241377篇
口腔科学   48752篇
临床医学   151456篇
内科学   333920篇
皮肤病学   38675篇
神经病学   131319篇
特种医学   63945篇
外国民族医学   242篇
外科学   257664篇
综合类   38950篇
现状与发展   4篇
一般理论   531篇
预防医学   124303篇
眼科学   40219篇
药学   123701篇
  7篇
中国医学   4483篇
肿瘤学   101416篇
  2021年   12819篇
  2019年   13543篇
  2018年   19985篇
  2017年   15237篇
  2016年   16643篇
  2015年   18985篇
  2014年   26255篇
  2013年   37997篇
  2012年   52806篇
  2011年   55520篇
  2010年   32830篇
  2009年   30735篇
  2008年   51600篇
  2007年   54913篇
  2006年   55349篇
  2005年   52645篇
  2004年   50845篇
  2003年   48240篇
  2002年   46464篇
  2001年   91841篇
  2000年   93654篇
  1999年   77003篇
  1998年   19733篇
  1997年   17277篇
  1996年   17404篇
  1995年   16756篇
  1994年   15296篇
  1993年   14078篇
  1992年   57406篇
  1991年   55293篇
  1990年   52998篇
  1989年   50769篇
  1988年   46166篇
  1987年   44957篇
  1986年   42247篇
  1985年   40004篇
  1984年   29359篇
  1983年   24915篇
  1982年   13903篇
  1979年   25545篇
  1978年   17579篇
  1977年   14911篇
  1976年   13883篇
  1975年   14569篇
  1974年   17639篇
  1973年   16953篇
  1972年   15679篇
  1971年   14457篇
  1970年   13437篇
  1969年   12522篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
21.
The present study compared four different sites and conditions for the measurement of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in 38 spontaneous breathing tracheotomised patients. Of the patients, 28 had chronic obstructive pulmonary disease (COPD). The four different conditions were: 1) through a cuff inflated cannula (condition A); 2) through the mouth with a deflated cannula (condition B); 3) through the mouth with a phonetic uncuffed cannula (condition C); and 4) through the mouth after stoma closure (condition D). Five trials in each condition were performed using a standardised method. The measurement of both MIP and MEP differed significantly depending on the condition of measurement. MIP taken in condition A was significantly higher when compared with conditions B, C and D. MEP in condition A was significantly higher when compared with condition B and D. In condition A the highest frequency of the best measurement of MIP and MEP was observed at the fourth and fifth effort, respectively. The same results were obtained after the selection of only COPD patients. In conclusion, respiratory muscle assessment differs significantly depending on measurement condition. Measurement through inflated cannula tracheotomy yields higher values of both maximal inspiratory and maximal expiratory pressure.  相似文献   
22.
23.
Summary: A female patient with isovaleric acidaemia had a successful outcome from pregnancy.  相似文献   
24.
25.
26.
AIM: The innovations for disease management need to be thoroughly evaluated so that their benefits and potential downsides can be compared with the already existing approaches. Endovascular laser (EVL) treatment for varicose veins offers today several advantages over surgical standard stripping. The Italian Endovenous-laser Working Group (IEWG) is a homogeneous group of surgeons and phlebologists who have been using EVL since 1999 and has undertaken to examine EVL in a multicenter study starting from a well defined rationale, with the benefit of a single protocol to use. METHODS: In a cooperative, multicenter, clinical study, 1076 limbs in 1050 patients, mean age of 54.5 years, 241 males and 809 females affected by chronic venous insufficiency (CVI) were considered eligible for surgery and stratified by CEAP classification in a four-year period (January 1999 December 2003). Inclusion criteria were insufficiency of the great and/or small saphenous vein at various levels, beyond those accessory saphenous trunks with incompetence in the saphenofemoral junction. In all cases truncular reflux apparead up on duplex scan examination, with or without associated varicosities. All the patients underwent a surgery on the basis of the clinical assessment. All the centres involved performed treatment in conformity with the Food and Drug Administration (FDA) validated procedure, using an endo-laser venous system kit with a 810-980 nm diode. Duplex scan was performed in all patients after 36 months with very few lost to follow-up cases. RESULTS: In the immediate postoperative period the results have been impressive, with a very effective closure of incompetent great saphenous vein and the other treated varicose veins (the early occlusion rate has been 99%). Major complications have not been detected: in particular, no deep venous thrombosis (DVT) evaluated duplex ultrasound. The patients' acceptability and satisfaction regarding the procedure, have been measured by means of a questionnaire on the quality of life, and the result was 96.7%. After 36 months, the total occusion rate of saphenous trunks has been 97%. CONCLUSIONS: The first important Italian experience with EVL based on preoperative, perioperative and postoperative duplex control and which is also based on the patients' satisfaction at mid/long-term has indicated some advantages over the standard treatment with the stripping method. In terms of reduced postoperative pain, shorter sick leave, a faster resumption of the normal activities, and, in particular, the total absence of DVT, we can conclude that EVL is a good solution for all patients with anatomic and hemodinamic patterns for saphenous vein surgery.  相似文献   
27.

Background  

A public hospital in New Mexico required collection of 50% of estimated costs prior to elective surgeries for self-pay patients. This study assesses the impact of this policy on access to elective surgical procedures.  相似文献   
28.
29.
We aimed to evaluate the potential of the cerebrospinal fluid (CSF) axonal damage biomarker NfH(SMI35) in the laboratory-supported differential diagnosis of parkinsonian syndromes. Patients with idiopathic Parkinson's disease (PD; n = 22), multiple-system atrophy (MSA; n = 21), progressive supranuclear palsy (PSP; n = 21), corticobasal degeneration (CBD; n = 6), and age-matched controls (n = 45) were included. CSF levels of NfH(SMI35) were measured using ELISA. Levels of CSF NfH(SMI35) were elevated in PSP compared to PD and controls (P < 0.05 each). They were also significantly higher in MSA than in PD and controls (P < 0.05 each). NfH(SMI35) differentiated PD from PSP with a sensitivity of 76.5% and a specificity of 94.4%. Axonal damage as measured by CSF NfH(SMI35) is most prominent in the more rapidly progressive syndromes PSP and MSA as compared to PD or CBD. CSF NfH(SMI35) may therefore be of some value for the laboratory-supported differential diagnosis of atypical parkinsonian syndromes.  相似文献   
30.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  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