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   24098篇
  免费   1386篇
  国内免费   295篇
耳鼻咽喉   472篇
儿科学   329篇
妇产科学   273篇
基础医学   4343篇
口腔科学   573篇
临床医学   1951篇
内科学   4623篇
皮肤病学   890篇
神经病学   1805篇
特种医学   1480篇
外科学   2954篇
综合类   147篇
现状与发展   1篇
一般理论   5篇
预防医学   1073篇
眼科学   453篇
药学   2131篇
中国医学   284篇
肿瘤学   1992篇
  2023年   119篇
  2022年   497篇
  2021年   813篇
  2020年   404篇
  2019年   570篇
  2018年   651篇
  2017年   534篇
  2016年   733篇
  2015年   1089篇
  2014年   1304篇
  2013年   1434篇
  2012年   2164篇
  2011年   2048篇
  2010年   1171篇
  2009年   1064篇
  2008年   1452篇
  2007年   1350篇
  2006年   1146篇
  2005年   1009篇
  2004年   866篇
  2003年   757篇
  2002年   652篇
  2001年   576篇
  2000年   475篇
  1999年   403篇
  1998年   203篇
  1997年   157篇
  1996年   121篇
  1995年   122篇
  1994年   83篇
  1993年   77篇
  1992年   149篇
  1991年   161篇
  1990年   117篇
  1989年   148篇
  1988年   120篇
  1987年   129篇
  1986年   106篇
  1985年   105篇
  1984年   77篇
  1983年   73篇
  1982年   52篇
  1981年   54篇
  1980年   48篇
  1979年   50篇
  1978年   57篇
  1977年   49篇
  1976年   39篇
  1975年   31篇
  1973年   35篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.

Purpose

We investigated the influence of positive surgical margins (PSMs) and their locations on biochemical recurrence (BCR) according to risk stratification and surgical modality.

Methods

A total of 1,874 post-radical-prostatectomy (RP) patients of pT2–T3a between 2000 and 2010 at three tertiary centers, and who did not receive neoadjuvant/adjuvant therapy, were included in this study. Patients were stratified according to BCR risk: low risk (PSA <10, pT2a-b, and pGS ≤6), intermediate risk (PSA 10–20 and/or pT2c and/or pGS 7), and high risk (PSA >20 or pT3a or pGS 8–10). The median follow-up was 43 months.

Results

PSMs were a significant predictor of BCR in both the intermediate- and high-risk-disease groups (P = .001, HR 2.1, 95 % CI 1.3–3.4; P < .001, HR 2.8, 95 % CI 2.0–4.1). Positive apical margin was a significant risk factor for BCR in high-risk disease (P = .003, HR 2.0, 95 % CI 1.2–3.3), but not in intermediate-risk disease (P = .06, HR 1.7, 95 % CI 0.9–3.1). Positive bladder neck margin was a significant risk factor for BCR in both intermediate- and high-risk disease (P < .001, HR 5.4, 95 % CI 2.1–13.8; P = .001, HR 4.5, 95 % CI 1.8–11.4). In subgroup analyses, robotic RP provided comparable BCR-free survival regardless of risk stratification. Patients with PSMs showed similar BCR-free survival between open and robotic RP (log-rank, P = .897).

Conclusions

Post-RP PSMs were a significantly independent predictor of disease progression in high-risk disease as well as intermediate-risk disease. Both positive apical and bladder neck margins are also significant risk factors of BCR in high-risk disease. Patients with PSMs showed similar BCR-free survival between open and robotic surgery.  相似文献   
962.
The purpose of this study was to observe whether the results of the median nerve fascicle transfer to the biceps are equivalent to the classical ulnar nerve fascicle transfer, in terms of elbow flexion strength and donor nerve morbidity. Twenty‐five consecutive patients were operated between March 2007 and July 2013. The patients were divided into two groups. In Group 1 (n = 8), the patients received an ulnar nerve fascicle transfer to the biceps motor branch. In Group 2 (n = 15), the patients received a median nerve fascicle transfer to the biceps motor branch. Two patients with follow‐up less than six months were excluded. Both groups were similar regarding age (P = 0.070), interval of injury (P = 0.185), and follow‐up period (P = 0.477). Elbow flexion against gravity was achieved in 7 of 8 (87.5%) patients in Group 1, versus 14 of 15 (93.3%) patients in Group 2 (P = 1.000). The level of injury (C5‐C6 or C5‐C7) did not affect anti‐gravity elbow flexion recovery in both the groups (P = 1.000). It was concluded that the median nerve fascicle transfer to the biceps is as good as the ulnar nerve fascicle transfer, even in C5‐C7 injuries. © 2014 Wiley Periodicals, Inc. Microsurgery 34:511–515, 2014.  相似文献   
963.
964.
Risperidone, an atypical antipsychotic drug, has been discovered to have some beneficial effects beyond its original effectiveness. The present study examines the neuroprotective effects of risperidone against ischemic damage in the rat and gerbil induced by transient focal and global cerebral ischemia, respectively. The results showed that pre‐ and posttreatment with 4 mg/kg risperidone significantly protected against neuronal death from ischemic injury. Many NeuN‐immunoreactive neurons and a few F‐J B‐positive cells were found in the rat cerebral cortex and gerbil hippocampal CA1 region (CA1) in the risperidone‐treated ischemia groups compared with those in the vehicle‐treated ischemia group. In addition, treatment with risperidone markedly attenuated the activation of microglia in the gerbil CA1. On the other hand, we found that treatment with risperidone significantly maintained the antioxidants levels in the ischemic gerbil CA1. Immunoreactivities of superoxide dismutases 1 and 2, catalase, and glutathione peroxidase were maintained in the stratum pyramidale of the CA1; the antioxidants were very different from those in the vehicle‐treated ischemia groups. In brief, our present findings indicate that posttreatment as well as pretreatment with risperidone can protect neurons in the rat cerebral cortex and gerbils CA1 from transient cerebral ischemic injury and that the neuroprotective effect of risperidone may be related to attenuation of microglial activation as well as maintenance of antioxidants. © 2014 Wiley Periodicals, Inc.  相似文献   
965.

Background

The presence of fluid–fluid levels (FFLs) on osteosarcoma magnetic resonance imaging (MRI) is underestimated as a nonspecific finding; however, we hypothesized that FFL in conventional osteosarcoma may be indicative of chemoresistance.

Methods

In 567 stage IIB osteosarcoma patients, we evaluated the following: the incidence of FFL and their correlation with other clinicopathological variables; tumor volume change after chemotherapy and survival according to the presence of FFL; and the relationship between survival and the extent of FFL.

Results

One hundred eight (19 %) tumors showed FFL on initial MRI. FFL were correlated with proximal humeral location (P = 0.017), osteolytic on plain radiographs (P < 0.001), tumor enlargement after chemotherapy (P < 0.001), and poor histological response (P = 0.005). Large tumor (P < 0.01), proximal tumor location (P = 0.01), and presence of FFL (P < 0.01) were independent predictors of poor survival. Compared to the extensive FFL (more than one third of the tumor), small foci of FFL (less than one third of the tumor) showed a high tendency for tumor enlargement after chemotherapy (P < 0.001), poor histologic response (P = 0.001), and worse survival (P < 0.001).

Conclusions

FFL on initial MRI could predict tumor progression after chemotherapy. Notably, tumors with small foci of FFL (less than one third of the tumor) have a high propensity for poor outcome. Patients with this finding should be considered for risk-adapted therapy.  相似文献   
966.

Background

T1 gastric cancer can be diagnosed only by endoscopy and is almost curable by local treatment. It has been unclear how a multidetector-row computed tomography (CT) evaluation is valuable for clinical T1 patients.

Methods

Patients with clinical T1 disease, as diagnosed by endoscopy and treated with endoscopic submucosal dissection (ESD) or surgery between October 2000 and October 2007, were examined. The efficacy of CT was evaluated by the reversal rate of endoscopic T1 by CT, the incidence of clinical M1 disease, and the accuracy of diagnosing pathological N+ disease in patients who received surgery. To confirm metachronous distant and nodal metastases, the disease-free survival (DFS) also was evaluated.

Results

A total of 761 patients, 236 treated by ESD and 525 treated with surgery, were examined. None of the patients had an endoscopic diagnosis of clinical T1 reversed by CT. No clinical M1 disease was found. Among the 525 patients who underwent surgery, 8 showed clinical N+ disease (1.5 %), while 47 demonstrated pathological N+ disease (8.9 %). The accuracy, sensitivity, specificity, positive predictive value, and negative predictive values were 90.3, 4.3, 98.7, 25, and 91.3 %, respectively. The 5-year DFS rate was 93.6 % (95 % confidence interval 91.4–95.8 %).

Conclusions

The present study suggests that diagnostic value of CT is limited for staging of clinical T1 gastric cancer patients, because the reversal rate of endoscopic T1 by CT was very low, clinical M1 disease was rare, the diagnosis of N+ status was unreliable, and metachronous M1 and N+ findings were rare.  相似文献   
967.

Background

There is no consensus on the optimal method of primary tumor control, determined by preoperative clinical factors, during sentinel node (SN) navigation surgery for early gastric cancer (EGC). In this study, we investigated the accuracy of clinical diagnosis based on preoperative examination in patients with EGC and proposed surgical options for primary tumor control during SN navigation surgery.

Methods

We analyzed 815 patients with clinical stage IA gastric cancer who underwent gastrectomy at the National Cancer Center in Korea between March 2001 and February 2011. The clinical stage was determined by endoscopy, endoscopic ultrasonography, and abdominal computed tomography.

Results

The preoperative assessment of tumor depth and tumor size was accurate in 57.5 and 70.8 % of patients, respectively. Tumor depth and size were underestimated in 8 and 25.3 % of patients. The overall accuracy of histologic diagnosis by endoscopic biopsy was 87.2 %. Of those tumors diagnosed preoperatively as differentiated, 20.5 % revealed mixed histology of undifferentiated type.

Conclusions

The recommendation for SN biopsy may be limited to tumors sized 3 cm or smaller to avoid positive lateral margins and to minimize the risk of skip metastases. Endoscopic resection may safely be applied to small mucosal cancers, but other surgical options should be employed for undifferentiated large mucosal lesions, given their tendency for diffuse invasion. Full-thickness resection is preferable for submucosal cancers, to secure clear vertical margins.  相似文献   
968.

Background

In patients undergoing pancreatic resection (PR), identification of subgroups at increased risk for postoperative complications can allow focused interventions that may improve outcomes.

Study Design

Patients undergoing PR from 2005–2010 were selected from the American College of Surgeons National Surgical Quality Improvement Program database and categorized as having any history of cardiac disease (angina, congestive heart failure (CHF), myocardial infarction (MI), cardiac stent, or bypass) or as having acute cardiac disease (symptoms of CHF or angina within 30 days or MI within 6 months). These variables were utilized to examine the relationship between cardiac disease and outcomes after PR.

Results

The rate of serious complications and perioperative mortality in patients with any history of cardiac disease vs. those without was 34 vs. 24 % (p?<?0.001) and 4.5 vs. 2.0 % (p?<?0.001), respectively, and in patients with acute cardiac disease compared to patients without was 37 vs. 25 % (p?<?0.001) and 8.6 vs. 2.2 % (p?<?0.001), respectively. In multivariate analysis, the two cardiac disease variables remained associated with mortality.

Conclusions

In patients undergoing PR, cardiac disease is a significant risk factor for adverse outcomes. These observations are critical for meaningful informed consent in patients considering pancreatectomy.  相似文献   
969.
970.
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