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   293809篇
  免费   25183篇
  国内免费   17280篇
耳鼻咽喉   2626篇
儿科学   3812篇
妇产科学   5677篇
基础医学   34195篇
口腔科学   5121篇
临床医学   36889篇
内科学   47869篇
皮肤病学   3434篇
神经病学   15880篇
特种医学   10729篇
外国民族医学   130篇
外科学   32722篇
综合类   42208篇
现状与发展   59篇
一般理论   61篇
预防医学   18565篇
眼科学   7989篇
药学   29760篇
  215篇
中国医学   13670篇
肿瘤学   24661篇
  2024年   851篇
  2023年   4153篇
  2022年   10338篇
  2021年   13664篇
  2020年   10061篇
  2019年   9034篇
  2018年   9596篇
  2017年   8437篇
  2016年   8101篇
  2015年   12090篇
  2014年   15225篇
  2013年   14530篇
  2012年   21180篇
  2011年   23166篇
  2010年   14352篇
  2009年   11538篇
  2008年   15606篇
  2007年   15771篇
  2006年   15118篇
  2005年   14995篇
  2004年   10699篇
  2003年   9577篇
  2002年   8391篇
  2001年   7475篇
  2000年   7523篇
  1999年   7712篇
  1998年   4354篇
  1997年   4369篇
  1996年   3361篇
  1995年   3056篇
  1994年   2655篇
  1993年   1768篇
  1992年   2753篇
  1991年   2377篇
  1990年   2032篇
  1989年   1769篇
  1988年   1525篇
  1987年   1422篇
  1986年   1135篇
  1985年   901篇
  1984年   604篇
  1983年   464篇
  1982年   284篇
  1981年   270篇
  1980年   228篇
  1979年   313篇
  1978年   178篇
  1977年   139篇
  1974年   152篇
  1973年   128篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Background The incidence rate of incisional hernias after open surgery has been reported to be higher than that of port site hernias after laparoscopic surgery. No studies have compared the costs for the health care system in treating those two types of hernia. Methods A systematic review was conducted to obtain the baseline data, and a decision analysis model was created to simulate the occurrence and recurrence of incisional and port site hernias. Results The overall risk of having incisional hernias was eight-times higher than that of having port site hernias (7.4% vs 0.9%). A cost savings of £93 per patient can be generated for the health care system in the UK. Similar results were obtained for Germany, Italy and France. Conclusions The additional treatment costs for incisional hernia should be taken into account when the costs of a surgery performed by open approach are compared with by laparoscopy.  相似文献   
82.
无线网络技术在医学仪器中的应用   总被引:1,自引:0,他引:1  
简要介绍无线网络技术的原理、特点及其在医学仪器中的应用.  相似文献   
83.
OBJECTIVES: To compare the sensitivity of rotational chair (ROTO) versus electronystagmography (ENG) in peripheral vestibular pathology. METHODS: Retrospective chart review. RESULTS: One thousand consecutive patients undergoing evaluation for dizziness and imbalance at a tertiary care referral balance center were reviewed. ROTO was the primary vestibular study used in all patients with ENG used as a confirmatory test at the discretion of the treating physician. A subgroup of 478 patients underwent both ROTO and ENG. Among the patients diagnosed with peripheral vestibulopathy, sensitivity for peripheral vestibulopathy was 71% for ROTO and 31% for ENG. However, specificity was 54% for ROTO and 86% for ENG. CONCLUSIONS: We conclude that in this retrospective cohort with the authors' clinical diagnoses, ROTO is a more sensitive diagnostic study of peripheral vestibular pathology. The higher sensitivity of ROTO and the higher specificity of ENG may support the use of ROTO as the primary vestibular study and ENG as a supplemental vestibular study. Prospective analysis with distinct diagnostic criteria and defined inclusion criteria are necessary before these results can be widely extrapolated.  相似文献   
84.
The aim of this study was to compare the demographic and clinical characteristics of individuals with affective disorders who had attempted suicide at some time in their lives and those who had not made a suicide attempt. In a Chinese rural community, individuals with suicide attempt (N = 30) and those without suicide attempt (N = 166) were assessed with Present State Examination (PSE). Attempters had a significantly higher level of family economic status, higher rate of lifetime depressed mood and hopelessness, and delusions than nonattempters. The logistic regression models also indicated that depressed mood and hopelessness were the most important predictors of suicide attempts. No significant difference in treatment condition was found between attempters and non-attempters. Early identification and interventions focusing on reducing depressed mood, hopelessness, and controlling psychotic symptoms may be helpful in reducing the risk of suicide attempts among individuals with affective disorders residing in the community.  相似文献   
85.
Objectives: To determine interobserver agreement between radiologists for computed tomography (CT) angiography and venography. CT venography of the lower extremities combined with standard CT angiography of the chest may result in an increased overall diagnosis rate of venous thromboembolism (pulmonary embolism or deep venous thrombosis).
Methods: The study had a retrospective cohort design. The population consisted of emergency department patients who were evaluated for suspected pulmonary embolism. A random sample of 50 patients diagnosed and treated for venous thromboembolism and 50 age- and gender-matched patients whose CT angiograms and venograms were read as negative were enrolled. The original reading (R1) was compared with readings of two study radiologists: R2, a general radiologist, and R3, a radiologist with fellowship training in cross-sectional imaging. All readers were blinded to each other.
Results: Both R2 and R3 found both CT angiogram and venogram components technically adequate in 95% (95% CI = 89% to 98%) and 86% (95% CI = 78% to 92%) of studies, respectively. The agreement was very good for CT angiography (lowest agreement = 92%; lowest κ = 0.83) and was good for CT venography (85%, κ = 0.65). In nine cases, R1 read the CT angiogram as negative but the venogram as positive for DVT, whereas both R2 and R3 read both components as negative in four of these nine, suggesting a false-positive isolated DVT rate of 44% (95% CI = 19% to 73%). In no case did R1 read both scan components as negative when R2 and R3 agreed on presence of pulmonary embolism or DVT.
Conclusions: Diagnosis of pulmonary embolism on CT angiography is more reliable than diagnosis of isolated DVT on CT venography.  相似文献   
86.
BACKGROUND: There are limited studies of large cohorts of patients with specific polysaccharide antibody deficiency (SPAD) syndrome. OBJECTIVE: To study the clinical and laboratory characteristics of patients with specific polysaccharide antibody deficiency syndrome. METHODS: We retrospectively studied 75 patients with total IgG levels of at least 500 mg/dL and fewer than 9 of 12 responses to vaccination with pneumococcal vaccine polyvalent. Exclusion criteria included an IgG level less than 500 mg/dL, established immunodeficiency syndrome, and secondary immunodeficiency. RESULTS: The most common clinical presentation was frequent infections (n = 69; 92%), including sinusitis (n = 53; 77%), pneumonia (n = 29; 42%), ear infections (n = 18; 26%), and bronchitis (n = 19; 28%). Other presentations were systemic infections (n = 5; 7%), autoimmune or rheumatic diseases (n = 6; 8%), and chronic diarrhea (n = 4; 5%). The median IgG2 level of patients with no response to pneumococcal vaccine polyvalent tended to be lower than that of patients with at least 1 response (150 vs 193 mg/dL, respectively; P = .06). There was no association between total IgG level (categorized as 500-600 or > or = 600 mg/dL) and frequency of infection (P = .43). Patients with fewer responses to pneumococcal vaccine polyvalent and a higher frequency of infections were more likely to receive intravenous immunoglobulin (IVIG) therapy (P = .01 and .003, respectively). Treatment with IVIG significantly reduced the number of infections (P < .001). CONCLUSION: Patients with no response to pneumococcal vaccine polyvalent tended to have lower IgG2 levels; those with fewer responses were more likely to receive IVIG therapy.  相似文献   
87.
In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished.  相似文献   
88.
全同非典进行特死斗争过程中,医护人员表现出一种临危不惧、挺身而出、全力救治、不怕牺牲、恪尽职守、患者至上、竭诚服务、科学防治的“抗非典精神”值得宣传,学习和效法。  相似文献   
89.

Purpose  

Hepatitis B virus (HBV) is endemic in Bangladesh, and the quality of life (QoL) of these patients remains unknown as there is no instrument available in the native language. In this study, we translated the 56-item Hepatitis Quality of Life Questionnaire (HQLQ) into Bengali and evaluated its validity and reliability.  相似文献   
90.
The levels and temporal variations of surface ozone at a coastal site in East China during summer and autumn were analyzed and the influences of meteorological parameters on ozone were investigated. An inland city was chosen as a comparison site. The main results and conclusions of this study are: (1) ozone pollution, with a maximum 1 h concentration of 150.98 ppbv, was severe during summer and autumn at the coastal site; (2) the ozone level was obviously higher at the coastal site than that at the inland site in September; (3) besides temperature and solar radiation, sea-land breeze circulation is an important factor influencing the ozone level at the coastal site, and sea breeze often induce high ozone levels (the average ozone concentration for sea breeze was about 13 ppbv higher than that for land breeze).  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