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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   18180篇
  免费   356篇
  国内免费   74篇
耳鼻咽喉   219篇
儿科学   351篇
妇产科学   374篇
基础医学   2015篇
口腔科学   650篇
临床医学   1380篇
内科学   4565篇
皮肤病学   218篇
神经病学   2024篇
特种医学   643篇
外科学   2858篇
综合类   41篇
一般理论   2篇
预防医学   657篇
眼科学   283篇
药学   910篇
  2篇
中国医学   17篇
肿瘤学   1401篇
  2024年   177篇
  2023年   212篇
  2022年   462篇
  2021年   720篇
  2020年   462篇
  2019年   595篇
  2018年   617篇
  2017年   472篇
  2016年   532篇
  2015年   580篇
  2014年   761篇
  2013年   1001篇
  2012年   1442篇
  2011年   1507篇
  2010年   796篇
  2009年   758篇
  2008年   1093篇
  2007年   1093篇
  2006年   945篇
  2005年   929篇
  2004年   905篇
  2003年   700篇
  2002年   651篇
  2001年   96篇
  2000年   56篇
  1999年   86篇
  1998年   132篇
  1997年   118篇
  1996年   88篇
  1995年   78篇
  1994年   72篇
  1993年   53篇
  1992年   40篇
  1991年   33篇
  1990年   43篇
  1989年   42篇
  1988年   25篇
  1987年   19篇
  1986年   31篇
  1985年   16篇
  1984年   25篇
  1983年   24篇
  1982年   25篇
  1981年   16篇
  1980年   18篇
  1979年   9篇
  1978年   10篇
  1976年   7篇
  1973年   4篇
  1969年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Surgical treatment of pancreatic cancer is to date the only modality that offers a chance of long-term survival. Potentially curative surgery is an option for only about 15% of patients with pancreatic adenocarcinoma. The aim of this study was to determine the survival and to assess the association of clinical, pathological, and treatment features with survival of patients who underwent resection of pancreatic cancer at the Department of Surgery of Udine University Hospital. From November 1989 to December 2005, 137 consecutive patients, who underwent surgical procedures for pancreatic cancer, were followed in our department. We performed 76 pancreatico-duodenectomy, 26 distal pancreatectomies and 35 total pancreatectomies. The surgical reconstruction after pancreatico-duodenectomy was as follows: 11 closures of the main duct with manual nonabsorbable stitches, 24 closures of the main duct with a linear stapler, 17 occlusions of the main duct with neoprene glue and 24 duct-to-mucosa anastomoses. Mean survival time was 27.7 +/- 26.93 months (mean +/- SD) and mean disease-free survival time was 25.4 +/- 23.06 months (mean +/- SD). 1, 3, 5, 7 and 9-year survival rates were 63.9, 33.7, 21.17, 12.7 and 10.2%, respectively. Significant differences in survival were recorded by the Log-rank test for age > 70 (p = 0.001), surgical procedures (p = 0.00046) and presence of metastases (p = 0.0055) The treatment of pancreatic cancer is undertaken with two different aims. The first is radical surgery for patients with early-stage disease, mainly stage I and partly stage II. In all other cases, the aim of treatment is the palliation of the several distressing symptoms related to this cancer. The standard treatment option for resectable tumours is radical pancreatic resection according to the Whipple procedure or total pancreatectomy.  相似文献   
43.
44.
45.
To investigate a possible antinociceptive role of serotonin receptor subtype 3 (5-HT(3)), we evaluated the effects of a coadministration of ondansetron, a 5-HT(3) selective antagonist, and tramadol, a central analgesic dependent on enhanced serotonergic transmission. Fifty-nine patients undergoing ear, throat, and nose surgery, using tramadol for 24-h postoperative patient-controlled analgesia (bolus = 30 mg; lockout interval = 10 min) were randomly allocated either to a group receiving ondansetron continuous infusion (1 mg. mL(-1). h(-1)) for postoperative nausea and vomiting (Group O) or to a control group receiving saline (Group T). Pain and vomiting scores and tramadol consumption were evaluated at 4, 8, 12, and 24 h. Pain scores were never >4, according to a 0-10 numerical rating scale, in both groups. Group O required significantly larger doses of tramadol at 4 h (213 versus 71 mg, P < 0.001), 8 h (285 versus 128 mg, P < 0.002), and 12 h (406 versus 190 mg, P < 0.002). Vomiting scores were higher in Group O at 4 h (P < 0.05) and 8 h (P = 0.05). We conclude that ondansetron reduced the overall analgesic effect of tramadol, probably blocking spinal 5-HT(3) receptors. IMPLICATIONS: Serotonin is an important neurotransmitter of the descending pathways that down-modulate spinal nociception. In postoperative pain, ondansetron, a selective 5-HT(3) receptor antagonist, increased the analgesic dose of tramadol. We suggest that, when antagonized for antiemetic purpose, 5-HT(3) receptors foster nociception, because of their site-dependent action.  相似文献   
46.
Background: Recently, various studies have questioned the efficacy of intraoperative acute normovolemic hemodilution (ANH) in reducing bleeding and the need for allogeneic transfusions in cardiac surgery. The aim of the present study was to reevaluate the effects of a low-volume ANH in elective, adult open-heart surgery.

Methods: Two hundred four consecutive adult patients undergoing cardiac surgery were prospectively randomized in a nonblinded manner into two groups: ANH group (103 patients), where 5-8 ml/kg of blood was withdrawn before systemic heparinization and replaced with colloid solutions, and a control group, where no hemodilution was performed (101 patients). Procedures included single and multiple valve surgery, aortic root surgery, coronary surgery combined with valve surgery, or partial left ventriculectomy. The purpose of the study was to evaluate the efficacy of ANH in reducing the need for allogeneic blood components. Routine hematochemical evaluations, perioperative blood loss, major complications, and outcomes were also recorded.

Results: No differences were found between the groups regarding demographics, baseline hematochemical data, and operative characteristics. There was no difference in the amount of transfusions of packed red cells, fresh frozen plasma, platelet concentrates, total number of patients transfused (control group, 36%vs. ANH group, 34.3%;P = 0.88), and amount of postoperative bleeding (control group, 412 ml [313-552 ml]vs. ANH group, 374 ml [255-704 ml]) (median [25th-75th percentiles]);P = 0.94. Further, perioperative complications, postoperative hematochemical data, and outcomes were not different.  相似文献   

47.
Arterial-venous extracorporeal membrane oxygenation (ECMO) is more and more used as first line mechanical support in acute cardiopulmonary failure. Important pitfall of this technique is the inappropriate unloading of left ventricle (LV) in case of myocardial insufficiency, leading to pulmonary stasis and inadequate myocardial recovery. We report our experience of left side unloading by a 7-F pigtail, introduced in the LV through the aortic valve, connected to the venous drainage. Echographic guidance is sufficient to pigtail positioning and follow-up monitoring avoiding catheterization laboratory transport. With this approach we were able to support three different patients, resolving LV distension and preventing lung congestion, without major complication.  相似文献   
48.

Context

Although magnetic resonance imaging (MRI) is emerging as the most commonly used imaging modality for prostate cancer (PCa) detection, treatment planning, and follow-up, its acceptance has not been uniform. Recently, great interest has been shown in multiparametric MRI, which combines anatomic T2-weighted (T2W) imaging with MR spectroscopic imaging (MRSI), dynamic contrast-enhanced MRI (DCE-MRI), and diffusion-weighted imaging (DWI).

Objective

The aim of this article is to review the current roles of these MR techniques in different aspects of PCa management: initial diagnosis, biopsy strategies, planning of radical prostatectomy (RP) and external radiation therapy (RT), and implementation of alternative focal therapies.

Evidence acquisition

The authors searched the Medline and Cochrane Library databases (primary fields: prostatic neoplasm, magnetic resonance). The search was performed without language restriction from January 2008 to November 2010.

Evidence synthesis

Initial diagnosis: The data suggest that the combination of T2W MRI and DWI or MRSI with DCE-MRI has the potential to guide biopsy to the most aggressive cancer foci in patients with previously negative biopsies, increasing the accuracy of the procedure. Transrectal MR-guided prostate biopsy can improve PCa detection, but its availability is still limited and the examination time is rather long. Planning of RP: It appears that adding MRSI, DWI, and/or DCE-MRI to T2W MRI can facilitate better preoperative characterization of cancer with regard to location, size, and relationship to prostatic and extraprostatic structures, and it may also facilitate early detection of local recurrence. Thus, use of these MR techniques may improve surgical, oncologic, and functional management. Planning of external RT and focal therapies: MR techniques have similar potential in these areas, but the published data remain very limited.

Conclusions

MRI technology is continuously evolving, and more extensive use of MRI technology in clinical trials and practice will help to improve PCa diagnosis and treatment planning.  相似文献   
49.

Objective:

To evaluate the short-term outcomes of laparoscopic colorectal surgery for cancer in the elderly compared with younger patients.

Methods:

We retrospectively considered a consecutive unselected series of 159 patients who underwent elective laparoscopic procedures for colorectal cancer at our institution between January 2007 and December 2009. Of these patients, 101 (63.5%) were ≤70 years of age (Group A), and 58 (36.5%) were >70 (Group B). Operative steps and instrumentation were standardized. Demographics, disease-related, operative, and short-term data were analyzed for each group, and an appropriate statistical comparison was made. Comorbidity was quantified by using the Charlson Comorbidity Index.

Results:

We reviewed right colectomies (29.5%), left colectomies (44.7%), rectal resections (19.5%), and other procedures (6.3%). There was no significant difference in sex ratio, body mass index, American Society of Anesthesiology score, type of surgical procedures, and tumor stage between Group A and Group B. A statistically higher comorbidity according to the Charlson index characterized Group B (2.2 vs 3.8; P=.034). Median operative time (228±78.1min vs 224.3±97.6min; NS), estimated blood loss (50.0±94.8mL vs 31.2±72.7mL; NS), conversion rate (2.0% vs 1.7%; NS), and timing to canalization (4.5±1.7dd vs 4.4±1.3dd; NS) were statistically comparable in both Groups. Group B was associated with a significantly longer length of hospital stay compared with Group A (8.1±2.8dd vs 10.8±6.6dd; P<.01) There was no statistically significant difference in major postoperative complications (3.8% vs 3.4%; NS), reoperations (0.9% vs 1.7%; NS), and 30-day mortality (0% vs 1.7%; NS).

Conclusions:

Laparoscopic colorectal surgery appears feasible and safe in elderly patients with increased comorbidity.  相似文献   
50.
Benign multicystic peritoneal mesothelioma (BMPM) is a rare disease with good short-term prognosis and rare malignant transformation. However, its biological significance remains unexplained. A neoplastic origin is considered by many authors to require a surgical excision, based on the high recurrence and progressive growth rate of the tumors. However, alternative or integrative treatment options have also been proposed. A 45-year-old woman presented to our unit with a history of occasional discomfort and pain in the left hip. On physical examination, we noticed a tough-elastic, fixed mass located in the iliac fossa. Computed tomography scan detected a mass with multiseptated cystic-like areas. Due to the similarity of these findings to a primitive sarcomatous tumor of the retroperitoneum, an arteriographic study was also performed. The patient underwent en bloc resection of the mass, including a segment of the sigmoid colon. The final pathologic diagnosis was cystic mesothelioma. Further studies are needed to better understand the etiology and pathogenesis of this rare disease, and to define a more tailored treatment plan.  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