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   2727800篇
  免费   208670篇
  国内免费   6031篇
耳鼻咽喉   36169篇
儿科学   90474篇
妇产科学   75588篇
基础医学   387335篇
口腔科学   77664篇
临床医学   247386篇
内科学   535404篇
皮肤病学   62782篇
神经病学   217563篇
特种医学   103052篇
外国民族医学   696篇
外科学   411505篇
综合类   63926篇
现状与发展   7篇
一般理论   948篇
预防医学   209107篇
眼科学   64017篇
药学   197017篇
  7篇
中国医学   6592篇
肿瘤学   155262篇
  2019年   21928篇
  2018年   31473篇
  2017年   23848篇
  2016年   26536篇
  2015年   29922篇
  2014年   41980篇
  2013年   62273篇
  2012年   85369篇
  2011年   90489篇
  2010年   53355篇
  2009年   50287篇
  2008年   83698篇
  2007年   88870篇
  2006年   89713篇
  2005年   86346篇
  2004年   83079篇
  2003年   79190篇
  2002年   76336篇
  2001年   138660篇
  2000年   142165篇
  1999年   117701篇
  1998年   32330篇
  1997年   28517篇
  1996年   28598篇
  1995年   27365篇
  1994年   24974篇
  1993年   23250篇
  1992年   89728篇
  1991年   86113篇
  1990年   82865篇
  1989年   79544篇
  1988年   72811篇
  1987年   71153篇
  1986年   66656篇
  1985年   63472篇
  1984年   47400篇
  1983年   40098篇
  1982年   23379篇
  1981年   20803篇
  1979年   41807篇
  1978年   29103篇
  1977年   24480篇
  1976年   23040篇
  1975年   23960篇
  1974年   29006篇
  1973年   27980篇
  1972年   26059篇
  1971年   23908篇
  1970年   22536篇
  1969年   21014篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  相似文献   
52.

Purpose

Endovascular treatment with mechanical thrombectomy devices demonstrated high recanalization rates but functional outcome did not correlate with high rates of recanalization obtained. Patient selection prior to the endovascular treatment is very important in the final outcome of the patient. The primary aim of our study was to evaluate the prognostic value of posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS) and Pons-Midbrain Index (PMI) scores in patients with Basilar Artery Occlusion (BAO) treated with successful angiographic recanalization after mechanical thrombectomy.

Methods

Retrospective single-center study including 18 patients between 2008 and 2013 who had acute basilar artery occlusion managed with endovascular treatment within 24 hours from symptoms onset and with successful angiographic recanalization. The patients were initially classified into two groups according to clinical outcome and mortality at 90 days. For analysis we also divided patients into groups based on pc-ASPECTS (≥8vs.< 8) and PMI (≥3vs.< 3) on non-contrast CT (NCCT) and CT Angiography Source Images (CTASI). Imaging data were correlated to clinical outcome and mortality rate.

Results

CTASI pc-ASPECTS, dichotomized at < 8 versus≥8, was associated with a favorable outcome (RR: 2.6; 95% CI: 1.3-5.2) and a reduced risk of death (RR: 6.5: 95% CI: 7.8-23.3). All patients that survived and were functionally independent had pc-ASPECTS score≥8. None of the 5 patients with CTASI pc-ASPECTS score less than 8 survived.

Conclusion

PC-ASPECTS on CTASI is helpful for predicting functional outcome after BAO recanalization with endovascular treatment. These results should be validated in a randomized controlled trial in order to decide whether or not to treat a patient with BAO.  相似文献   
53.
54.
55.
56.
Objective: Human epidermal growth factor receptor 2 (erbb2/HER2) overexpression, has now been implicatedin advanced gastric and gastroesophageal junction cancers. The study was conducted to determine the rate of HER2positivity in patients with locally advanced or metastatic gastric and gastroesophageal adenocarcinoma in North-EastIndia and to assess the impact of various demographic and clinical parameters on HER2 positivity. Methods: A total of68 patients of age >18 years of gastric and gastroesophageal adenocarcinoma diagnosed on histopathological examinationfrom September 2016 to February 2018 at Dr B Borooah Cancer Institute, Assam were enrolled for the observational(epidemiological) study. All patients were subjected to the HER2 immunohistochemistry test using a FDA-approved,standardized test kit. HER2 expression was correlated with various demographic and clinicopathological parameters.Results: The overall rate of HER2 positivity in the population studied was 56% (n=38). The rate was non-significantlyhigher in male, older age group (>60 years) and Hindu population. Similarly, HER2 positivity rate was higher in patientswith well differentiated histology and was more common in patients with stage II and III diseases, but neither of theassociations is statistically significant. HER2 positivity rate was significantly higher in proximal and in GEJ tumours(56% versus 44%, P=0.002). Conclusion: HER2 overexpression was evident in 56% of the North-East Indian patientswith locally advanced and metastatic gastric and gastroesophageal adenocarcinoma. The overexpression correlatedsignificantly with primary tumour site. Routine testing of gastric and gastroesophageal tumours for HER2 expressionis recommended to provide a therapeutic advantage in Indian patients.  相似文献   
57.
58.

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   
59.
Metabolism describes the series of chemical reactions that are concerned with the provision of energy to biological systems. They may be divided into reactions involved in energy yield (catabolism: demand exceeds supply), and energy storage (anabolism: supply exceeds demand). Regulation of these pathways is critical for homeostasis, and derangements in metabolism are seen in a wide variety of pathological processes. Understanding metabolism is key to the treatment of many diseases, notably diabetes, as well as underpinning clinical nutritional support.  相似文献   
60.
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