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   10674篇
  免费   652篇
  国内免费   22篇
耳鼻咽喉   119篇
儿科学   297篇
妇产科学   199篇
基础医学   1614篇
口腔科学   145篇
临床医学   1004篇
内科学   1785篇
皮肤病学   445篇
神经病学   1209篇
特种医学   423篇
外国民族医学   2篇
外科学   1821篇
综合类   101篇
一般理论   1篇
预防医学   708篇
眼科学   153篇
药学   709篇
中国医学   39篇
肿瘤学   574篇
  2022年   59篇
  2021年   149篇
  2020年   120篇
  2019年   132篇
  2018年   182篇
  2017年   163篇
  2016年   176篇
  2015年   211篇
  2014年   237篇
  2013年   361篇
  2012年   498篇
  2011年   536篇
  2010年   326篇
  2009年   302篇
  2008年   437篇
  2007年   496篇
  2006年   478篇
  2005年   482篇
  2004年   425篇
  2003年   405篇
  2002年   399篇
  2001年   414篇
  2000年   384篇
  1999年   317篇
  1998年   150篇
  1997年   113篇
  1996年   86篇
  1995年   77篇
  1994年   73篇
  1993年   74篇
  1992年   170篇
  1991年   186篇
  1990年   138篇
  1989年   155篇
  1988年   165篇
  1987年   150篇
  1986年   157篇
  1985年   112篇
  1984年   102篇
  1983年   104篇
  1982年   66篇
  1979年   72篇
  1978年   66篇
  1977年   61篇
  1975年   69篇
  1974年   65篇
  1973年   81篇
  1972年   56篇
  1971年   66篇
  1970年   58篇
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
41.
Background: The purpose of this study was to evaluate the tumor characteristics and treatment associated with an improved overall survival in patients with adenocarcinoma of the small intestine. Methods: The records of all patients with primary adenocarcinoma of the small bowel seen between January 1971 and December 1991 were reviewed retrospectively. The study comprised 38 patients, 22 (58%) with duodenal tumors, 11 (29%) with jejunal tumors, and five (13%) with ileal tumors. Results: Although not statistically significant, the patients with duodenal adenocarcinoma lived longer than the patients with jejunal or ileal lesions (p=0.77). The overall survival was 23% and seemed to correlate best with absence of lymph node metastases (p=0.04) and pancreaticoduodenectomy for localized duodenal tumors (p=0.04). The patient's age, duration of symptoms, disease-free interval, tumor location, type of recurrence, and histologic grade did not significantly influence survival. Conclusions: The lethality of small-intestinal adenocarcinoma appears to be related to a delay in diagnosis and treatment. When a definitive surgical procedure is performed before lymph node metastases appear, the patient's chance for long-term survival is greatly improved.Presented at the 46th Annual Cancer Symposium of The Society of Surgical Oncology, Los Angeles, California, March 18–21, 1993.  相似文献   
42.
43.
Re-resection for gallbladder carcinoma incidentally discovered after cholecystectomy is routinely advocated. However, the incidence of finding additional disease at the time of re-resection remains poorly defined. Between 1984 and 2006, 115 patients underwent re-resection at six major hepatobiliary centers for gallbladder carcinoma incidentally discovered during cholecystectomy. Data on clinicopathologic factors, operative details, TNM tumor stage, and outcome were collected and analyzed. Data on the incidence and location of residual/additional carcinoma discovered at the time of re-resection were also recorded. On pathologic analysis, T stage was T1 7.8%, T2 67.0%, and T3 25.2%. The median time from cholecystectomy to re-resection was 52 days. At the time of re-resection, hepatic surgery most often consisted of formal segmentectomy (64.9%). Patients underwent lymphadenectomy (LND) (50.5%) or LND + common bile duct resection (43.3%). The median number of lymph nodes harvested was 3 and did not differ between LND alone (n = 3) vs LND + common duct resection (n = 3) (P = 0.35). Pathology from the re-resection specimen noted residual/additional disease in 46.4% of patients. Of those patients staged as T1, T2, or T3, 0, 10.4, and 36.4%, respectively, had residual disease within the liver (P = 0.01). T stage was also associated with the risk of metastasis to locoregional lymph nodes (lymph node metastasis: T1 12.5%; T2 31.3%, T3 45.5%; P = 0.04). Cystic duct margin status predicted residual disease in the common bile duct (negative cystic duct, 4.3% vs positive cystic duct, 42.1%) (P = 0.01). Aggressive re-resection for incidental gallbladder carcinoma is warranted as the majority of patients have residual disease. Although common duct resection does not yield a greater lymph node count, it should be performed at the time of re-resection for patients with positive cystic duct margins because over one-third will have residual disease in the common bile duct. Presented at the 48th Annual Meeting of the Society for Surgery of the Alimentary Tract at Digestive Week 2007, Plenary Session, Washington, DC, March 23, 2007.  相似文献   
44.
OBJECTIVE: A robust and fast algorithm for the offline detection of epileptic seizures in scalp EEG is described. It is aimed for seizure detection with high sensitivity and low number of false detections in long-term EEG data without a priori information. METHODS: To capture the characteristic electrographic changes of seizures, we developed an efficient method based on power spectral analysis techniques. The integrated power is calculated in two frequency bands for three multi-channel seizure detection montages (referenced against the average of Fz-Cz-Pz, common average, bipolar) using the same parameters for all montages and all patients taking into account an appropriate artifact rejection. RESULTS: A total of 3248 h of scalp recordings containing 148 seizures from 19 patients were examined. The averaged sensitivity was 90.9% and selectivity (false-positive errors/h, FPH) was 0.29/h of the Fz-Cz-Pz montage; the other montages yielded lower sensitivities but even better selectivity values. CONCLUSIONS: Taking into account that the method has been performed in a standardized way with fixed parameters for all patients and montages the obtained values for sensitivity are quite high while the selectivity is acceptably low. The parameters can additionally be tuned to patient specific seizures. It is assumed that this may further improve the seizure detection performance. SIGNIFICANCE: The proposed method may enhance the clinical use for the detection of seizures in scalp EEG long-term monitoring during presurgical evaluation.  相似文献   
45.
BACKGROUND: Chronic inflammation is associated with processes that contribute to the onset or progression of cancer. This study examined the relationships between circulating levels of the inflammatory markers interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-alpha) and total as well as site-specific cancer incidence. METHODS: Study subjects (n = 2,438) were older adults (ages 70-79 years) participating in the Health Aging and Body Composition study, who did not report a previous cancer diagnosis (except for nonmelanoma skin cancer) at baseline. Incident cancer events (n = 296) were ascertained during an average follow-up of 5.5 years. Inflammatory markers were measured in stored baseline fasting blood samples. RESULTS: The adjusted hazard ratios (95% confidence intervals) for incident cancer associated with a 1-unit increase on the natural log-scale were 1.13 (0.94-1.37), 1.25 (1.09-1.43), and 1.28 (0.96-1.70) for IL-6, CRP, and TNF-alpha, respectively. Markers were more strongly associated with cancer death: hazard ratios were 1.63 (1.19-2.23) for IL-6, 1.64 (1.20-2.24) for CRP, and 1.82 (1.14-2.92) for TNF-alpha. Although precision was low for site-specific analyses, our results suggest that all three markers were associated with lung cancer, that IL-6 and CRP were associated with colorectal cancer, and that CRP was associated with breast cancer. Prostate cancer was not associated with any of these markers. CONCLUSIONS: These findings suggest that (a) the associations between IL-6, CRP, and TNF-alpha and the risk of cancer may be site specific and (b) increased levels of inflammatory markers are more strongly associated with the risk of cancer death than cancer incidence.  相似文献   
46.
47.
48.
49.
50.
BACKGROUND. The antibody Ki-67 binds to nuclei in all cell cycle phases except GO and can be used to measure growth fraction. Because proliferative activity has been linked to prognosis in neoplasia, the authors analyzed 100 cases of colorectal carcinoma, each with 3 or more years of follow-up, using Ki-67 immunostaining. METHODS. The Ki-67-positive nuclear area and total nuclear area of carcinoma cells in 20 microscopic fields were measured by computed morphometry. A Ki-67 score (percent positive nuclear area x 100) was calculated. The following characteristics also were recorded for each case: patient age and sex, tumor site and size, modified Dukes' stage, spread beyond bowel wall, lymph node status, tumor grade, histologic type, extramural venous spread, tumor growth pattern, fibrosis, lymphocytic infiltration, and mitotic rate. RESULTS. Ki-67 scores ranged from 1 to 90 (mean, 34.6). Ki-67 scores were higher in Stage A disease (versus Stage B, C, and D disease) but were not associated with survival. Survival curves differed by stage, lymph node metastases, infiltrative growth pattern, lymphocytic infiltration, fibrosis, extramural venous spread, and tumor grade in a univariate analysis. The infiltrative growth pattern (P = 0.04) and lymphocytic infiltration (P = 0.003) were features associated independently with survival after adjusting for modified Dukes' stage. Furthermore, the lack of a significant lymphocytic infiltrate was associated with a death rate 3.4 times greater than that occurring in patients with Stage B disease with a significant infiltrate. CONCLUSIONS. The authors conclude that proliferative activity in colorectal carcinoma as measured by Ki-67 immunostaining was not associated with prognosis.  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