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   4754篇
  免费   586篇
  国内免费   9篇
耳鼻咽喉   9篇
儿科学   199篇
妇产科学   236篇
基础医学   795篇
口腔科学   99篇
临床医学   427篇
内科学   803篇
皮肤病学   142篇
神经病学   483篇
特种医学   109篇
外科学   571篇
综合类   129篇
一般理论   5篇
预防医学   586篇
眼科学   141篇
药学   302篇
中国医学   15篇
肿瘤学   298篇
  2021年   60篇
  2019年   59篇
  2018年   73篇
  2017年   65篇
  2016年   71篇
  2015年   57篇
  2014年   86篇
  2013年   128篇
  2012年   189篇
  2011年   179篇
  2010年   121篇
  2009年   107篇
  2008年   184篇
  2007年   226篇
  2006年   228篇
  2005年   179篇
  2004年   181篇
  2003年   178篇
  2002年   200篇
  2001年   179篇
  2000年   183篇
  1999年   169篇
  1998年   75篇
  1997年   52篇
  1996年   54篇
  1995年   40篇
  1994年   47篇
  1993年   57篇
  1992年   127篇
  1991年   112篇
  1990年   120篇
  1989年   118篇
  1988年   97篇
  1987年   108篇
  1986年   101篇
  1985年   100篇
  1984年   87篇
  1983年   76篇
  1982年   55篇
  1981年   37篇
  1980年   51篇
  1979年   67篇
  1978年   52篇
  1977年   46篇
  1976年   44篇
  1975年   45篇
  1974年   53篇
  1973年   52篇
  1972年   45篇
  1967年   35篇
排序方式: 共有5349条查询结果,搜索用时 31 毫秒
101.
Community-university partnerships for research and action are at the heart of many fields in the social sciences including public health, urban planning, education, and community psychology. These partnerships involve individuals from different backgrounds and disciplines working together to address social issues of importance to the community. This article proposes an interactive and contextual model for developing and sustaining community-university partnerships. The phases in the model include gaining entry into the community, developing and sustaining a mutual collaboration (developing trust and mutual respect, establishing adequate communication, respecting human diversity, establishing a culture of learning, respecting the culture of the setting and the community, and developing an action agenda), and recognizing the benefits and outcomes of partnership work. The model also includes the potential challenges that might threaten the partnership, such as resource inequality and time commitment.  相似文献   
102.
PURPOSE: This phase III randomized trial compared two chemotherapy regimens, gemcitabine plus carboplatin and mitomycin, ifosfamide, and cisplatin, in chemotherapy-naive patients with advanced non-small-cell lung cancer (NSCLC). The regimens were compared with regard to effects on survival, response rates, toxicity, and quality of life. PATIENTS AND METHODS: Eligible patients had previously untreated stage IIIB or IV NSCLC suitable for cisplatin-based chemotherapy. Randomly assigned patients were to receive four cycles, each at 3-week intervals, of carboplatin area under the curve of 5 on day 1 plus gemcitabine 1,200 mg/m(2) on days 1 and 8 (GCa) or mitomycin 6 mg/m(2), ifosfamide 3g/m(2), and cisplatin 50 mg/m(2) on day 1 (MIC). RESULTS: Between February 1999 and August 2001, 422 patients (GCa, n = 212; MIC, n = 210) were randomly assigned in the United Kingdom. The majority of patients received the intended four cycles (GCa, 64%; MIC, 61%). There was a significant survival advantage for GCa compared with MIC (hazard ratio, 0.76; 95% CI, 0.61 to 0. 93; P = .008). Median survival was 10 months with GCa and 7.6 months with MIC (difference, 2.4 months; 95% CI, 1.0 to 4.0), and 1-year survival was 40% with GCa and 30% with MIC (difference, 10%; 95% CI, 3% to 18%). Overall response rates were similar (42% for GCa v 41% for MIC; P = .84). More thrombocytopenia occurred with GCa (P = .03), but this was not associated with increased hospital admission or fatality. GCa caused less nausea, vomiting, constipation, and alopecia and was associated with fewer admissions for administration and better quality of life. CONCLUSION: In patients with advanced NSCLC, GCa chemotherapy was shown to be a better-tolerated treatment that conferred a survival advantage over MIC.  相似文献   
103.
Different theories have evolved to explain the pathogenesis and the cell of origin of intraneural ganglion cysts. Reportedly only three cases of intraneural ganglion of the tibial nerve have been located within the popliteal fossa, and all of these were thought to arise within the nerve. The authors report a case of a recurrent tibial intraneural ganglion in which a connection to the proximal tibiofibular joint was demonstrated on magnetic resonance (MR) images and at surgery. Surgical ligation of the articular branch and evacuation of the cyst led to symptomatic relief, and an MR image obtained 1 year after surgery documented no recurrence. This case reinforces the fact that surgeons need to consider and search for an articular connection in all cases of intraneural ganglia, especially in those that have recurred.  相似文献   
104.
An isolated avulsion fracture of the lesser tuberosity is an uncommon injury. We present five cases in adolescent athletes which demonstrate the radiographic, ultrasound, and MR appearances of this injury. Clinically and radiologically, the diagnosis can be difficult. In a setting of trauma, careful review of the imaging studies can lead to early diagnosis and appropriate treatment.  相似文献   
105.
106.
Analysis of Proficiency Analytical Testing (PAT) results between 2003 and 2013 suggest that the variation in respirable crystalline silica analysis is much smaller today than it was in the period 1990–1998, partly because of a change in sample production procedure and because the colorimetric method has been phased out, although quality improvements in the x-ray diffraction (XRD) or infrared (IR) methods may have also played a role. There is no practical difference between laboratories using XRD or IR methods or between laboratories which are accredited or those which are not. Reference laboratory means (assigned values) are not different from the means of all participants across the current range of mass loading, although there is a small difference in variance in the ratios of all participants to reference laboratory means based on method because the reference laboratories are much more likely to use XRD than are the others. Matrix interference does not lead to biases or substantially larger variances for either XRD or IR methods. Data from proficiency test sample analyses that include results from poorly performing laboratories should not be used to determine the validity of a method. PAT samples are not produced below 40 μg and variance may increase with lower masses, although this is not particularly predictable. PAT data from lower mass loadings will be required to evaluate analytical performance if exposure limits are lowered without change in sampling method. Task-specific exposure measurements for periods shorter than a full shift typically result in lower mass loadings and the quality of these analyses would also be better assured from being within the range of PAT mass loadings. High flow rate cyclones, whose performance has been validated, can be used to obtain higher mass loadings in environments of lower concentrations or where shorter sampling times are desired.  相似文献   
107.
108.
HIV infection increases the risk of psychological distress among adolescents living with HIV (ALHIV), which, in turn, increases risky behaviours such as medication non-adherence, substance use, and sexual risk-taking. The majority of studies on psychological distress among ALHIV have been conducted in high-income countries; data on the prevalence and correlates of psychological distress among ALHIV in sub-Saharan Africa (SSA) are scarce, yet over two-thirds of the global population of ALHIV resides in SSA. The purpose of this study was to identify the contextually relevant correlates of psychological distress among Ugandan ALHIV. Utilizing the stress and coping framework, we explored the risk and protective factors for psychological distress in cross-sectional sample of 464 ALHIV (aged 12–19; 53% female) at a large HIV treatment centre in Kampala, Uganda. The stressors associated with psychological distress included daily hassles, major negative life events, HIV-related quality of life, and stigma. Protective factors included psychosocial resources such as religious coping, satisfaction with social support, and general coping style and behaviours. Social support and optimism were significantly associated with psychological distress. Findings underscore the need for mental health services for ALHIV in Uganda and other resource-limited settings.  相似文献   
109.
Abstract. Wahlin S, Floderus Y, Stål P, Harper P (Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden). Erythropoietic protoporphyria in Sweden: demographic, clinical, biochemical and genetic characteristics. J Intern Med 2010; 269 : 278–288. Objective. To investigate the demographic, clinical, biochemical and genotypic features of patients with erythropoietic protoporphyria (EPP) in a Swedish cohort. Design. Cross‐sectional questionnaire, biochemical and genetic study. Setting. Sweden. Subjects. Fifty‐one Swedish individuals known in 2008 to have EPP confirmed by molecular diagnosis. There were no exclusion criteria; all patients were included in the demographic and genetic study. A total of 92% participants completed the questionnaire study and 82% the biochemical study. Results. The prevalence of EPP was 1 : 180 000. Nine novel ferrochelatase gene mutations were found. The most commonly reported age at onset of symptoms was the first year of life and the mean age at diagnosis was 22 years. Painful photosensitivity was the main symptom. Exogenous factors other than sunlight were frequently reported to cause cutaneous symptoms. One in five patients reported a positive effect of beta‐carotene therapy. A marked impact of EPP on quality of life was reported. Women had a significantly lower mean erythrocyte protoporphyrin concentration than men. Of all participants, 84% had insufficient vitamin D concentrations, 44% had below normal serum ferritin or transferrin saturation levels and red cell abnormalities were common. Conclusions. The notably delayed diagnosis suggests the need for an increased awareness of EPP. Disturbed erythropoiesis, biochemical signs of iron deficiency and low vitamin D levels are frequent findings in this disease. New and better treatments are needed as current treatment options for symptom amelioration are limited. Vitamin D supplementation should be considered.  相似文献   
110.
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