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   1021088篇
  免费   80845篇
  国内免费   2375篇
耳鼻咽喉   15036篇
儿科学   29815篇
妇产科学   28428篇
基础医学   145944篇
口腔科学   32786篇
临床医学   87020篇
内科学   199723篇
皮肤病学   21278篇
神经病学   83432篇
特种医学   40341篇
外国民族医学   197篇
外科学   155887篇
综合类   25920篇
现状与发展   4篇
一般理论   321篇
预防医学   83138篇
眼科学   23577篇
药学   74757篇
中国医学   2417篇
肿瘤学   54287篇
  2021年   8680篇
  2018年   12026篇
  2017年   9252篇
  2016年   9940篇
  2015年   11781篇
  2014年   16598篇
  2013年   23583篇
  2012年   33221篇
  2011年   34849篇
  2010年   19586篇
  2009年   18063篇
  2008年   30834篇
  2007年   33381篇
  2006年   32601篇
  2005年   32428篇
  2004年   31391篇
  2003年   29830篇
  2002年   27190篇
  2001年   40045篇
  2000年   40667篇
  1999年   34605篇
  1998年   10597篇
  1997年   9668篇
  1996年   9560篇
  1995年   8932篇
  1994年   8642篇
  1992年   28860篇
  1991年   28262篇
  1990年   27586篇
  1989年   26635篇
  1988年   24987篇
  1987年   24541篇
  1986年   23313篇
  1985年   22562篇
  1984年   17437篇
  1983年   14872篇
  1982年   9329篇
  1981年   8643篇
  1979年   17528篇
  1978年   12655篇
  1977年   10595篇
  1976年   9676篇
  1975年   10640篇
  1974年   13120篇
  1973年   12621篇
  1972年   11948篇
  1971年   11063篇
  1970年   10632篇
  1969年   10331篇
  1968年   9305篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Gestational trophoblastic neoplasia (GTN) patients are treated according to the eight-variable International Federation of Gynaecology and Obstetrics (FIGO) scoring system, that aims to predict first-line single-agent chemotherapy resistance. FIGO is imperfect with one-third of low-risk patients developing disease resistance to first-line single-agent chemotherapy. We aimed to generate simplified models that improve upon FIGO. Logistic regression (LR) and multilayer perceptron (MLP) modelling (n = 4191) generated six models (M1-6). M1, all eight FIGO variables (scored data); M2, all eight FIGO variables (scored and raw data); M3, nonimaging variables (scored data); M4, nonimaging variables (scored and raw data); M5, imaging variables (scored data); and M6, pretreatment hCG (raw data) + imaging variables (scored data). Performance was compared to FIGO using true and false positive rates, positive and negative predictive values, diagnostic odds ratio, receiver operating characteristic (ROC) curves, Bland-Altman calibration plots, decision curve analysis and contingency tables. M1-6 were calibrated and outperformed FIGO on true positive rate and positive predictive value. Using LR and MLP, M1, M2 and M4 generated small improvements to the ROC curve and decision curve analysis. M3, M5 and M6 matched FIGO or performed less well. Compared to FIGO, most (excluding LR M4 and MLP M5) had significant discordance in patient classification (McNemar's test P < .05); 55-112 undertreated, 46-206 overtreated. Statistical modelling yielded only small gains over FIGO performance, arising through recategorisation of treatment-resistant patients, with a significant proportion of under/overtreatment as the available data have been used a priori to allocate primary chemotherapy. Streamlining FIGO should now be the focus.  相似文献   
12.
13.
Cutaneous leiomyomas are rare benign smooth‐muscle tumors. These lesions are distinguished based on their cell of origin and are subclassified as pilar leiomyoma, angioleiomyoma, and genital‐type leiomyoma. Nipple leiomyoma is the least common genital‐type leiomyoma, arising from the dartoic muscle cell of the nipple. Histologic examination of the lesion is necessary for definitive diagnosis, and these uncommon tumors can pose a diagnostic challenge. We describe herein a series of six nipple leiomyomas with a spectrum of histologic appearances.  相似文献   
14.
15.
16.
17.
Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish‐eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH‐induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus‐2 (CPV‐2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH‐induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV‐2.  相似文献   
18.

Objective

Comparative survival between neoadjuvant chemotherapy and adjuvant chemotherapy for patients with cT2-4N0-1M0 non–small cell lung cancer has not been extensively studied.

Methods

Patients with cT2-4N0-1M0 non–small cell lung cancer who received platinum-based chemotherapy were retrospectively identified. Exclusion criteria included stage IV disease, induction radiotherapy, and targeted therapy. The primary end point was disease-free survival. Secondary end points were overall survival, chemotherapy tolerance, and ability of Response Evaluation Criteria In Solid Tumors response to predict survival. Survival was estimated using the Kaplan–Meier method, compared using the log-rank test and Cox proportional hazards models, and stratified using matched pairs after propensity score matching.

Results

In total, 330 patients met the inclusion criteria (n = 92/group after propensity-score matching; median follow-up, 42 months). Five-year disease-free survival was 49% (95% confidence interval, 39-61) for neoadjuvant chemotherapy versus 48% (95% confidence interval, 38-61) for adjuvant chemotherapy (P = .70). On multivariable analysis, disease-free survival was not associated with neoadjuvant chemotherapy or adjuvant chemotherapy (hazard ratio, 1.1; 95% confidence interval, 0.64-1.90; P = .737), nor was overall survival (hazard ratio, 1.21; 95% confidence interval, 0.63-2.30; P = .572). The neoadjuvant chemotherapy group was more likely to receive full doses and cycles of chemotherapy (P = .014/0.005) and had fewer grade 3 or greater toxicities (P = .001). Response Evaluation Criteria In Solid Tumors response to neoadjuvant chemotherapy was associated with disease-free survival (P = .035); 15% of patients receiving neoadjuvant chemotherapy (14/92) had a major pathologic response.

Conclusions

Timing of chemotherapy, before or after surgery, is not associated with an improvement in overall or disease-free survival among patients with cT2-4N0-1M0 non–small cell lung cancer who undergo complete surgical resection.  相似文献   
19.
20.
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