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   24245篇
  免费   1322篇
  国内免费   277篇
耳鼻咽喉   474篇
儿科学   329篇
妇产科学   273篇
基础医学   4336篇
口腔科学   581篇
临床医学   2012篇
内科学   4625篇
皮肤病学   888篇
神经病学   1807篇
特种医学   1474篇
外科学   2958篇
综合类   157篇
现状与发展   1篇
一般理论   5篇
预防医学   1089篇
眼科学   448篇
药学   2101篇
中国医学   284篇
肿瘤学   2002篇
  2023年   154篇
  2022年   512篇
  2021年   820篇
  2020年   404篇
  2019年   570篇
  2018年   646篇
  2017年   533篇
  2016年   738篇
  2015年   1085篇
  2014年   1304篇
  2013年   1447篇
  2012年   2165篇
  2011年   2056篇
  2010年   1176篇
  2009年   1077篇
  2008年   1460篇
  2007年   1338篇
  2006年   1146篇
  2005年   1016篇
  2004年   865篇
  2003年   761篇
  2002年   655篇
  2001年   580篇
  2000年   483篇
  1999年   401篇
  1998年   193篇
  1997年   151篇
  1996年   120篇
  1995年   128篇
  1994年   82篇
  1993年   70篇
  1992年   149篇
  1991年   153篇
  1990年   116篇
  1989年   147篇
  1988年   125篇
  1987年   123篇
  1986年   103篇
  1985年   102篇
  1984年   73篇
  1983年   66篇
  1982年   57篇
  1981年   50篇
  1980年   47篇
  1979年   49篇
  1978年   57篇
  1977年   53篇
  1976年   39篇
  1974年   30篇
  1973年   34篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.

Objective

To evaluate the efficacy of newly designed covered and non-covered coated colorectal stents for colonic decompression.

Materials and Methods

Twenty-six patients, (15 palliative cases and 11 preoperative) underwent treatment for the relief of colorectal obstruction using metallic stents positioned under fluoroscopic guidance. In 24 of the 26, primary colorectal carcinoma was diagnosed, and in the remaining two, recurrent colorectal carcinoma. Twenty-one patients were randomly selected to receive either a type A or type B stent; for the remaining five, type C was used. Type A, an uncovered nitinol wire stent, was lightly coated to ensure structural integrity. Type B (flare type) and C (shoulder type) stents were polyurethane covered and their diameter was 24 and 26mm, respectively. The rates of technical success, clinical success, and complications were analyzed using the chi-square test, and to analyse the mean period of patency, the Kaplan-Meier method was used.

Results

Thirty of 31 attempted placements in 26 patients were successful, with a technical success rate of 96.8% (30/31) and a clinical success rate of 80.0% (24/30). After clinically successful stent placement, bowel decompression occurred within 1-4 (mean, 1.58 ± 0.9) days. Five of six clinical failures involved stent migration and one stent did not expand after successful placement. In the preoperative group, 11 stents, one of which migrated, were placed in ten patients, in all of whom bowel preparation was successful. In the palliative group, 19 stents were placed in 15 patients. The mean period of patency was 96.25 ± 105.12 days: 146.25 ± 112.93 for type-A, 78.82 ± 112.26 for type-B, and 94.25 ± 84.21 for type-C. Complications associated with this procedure were migration (n=6, 20%), pain (n=4, 13.3%), minor bleeding (n=5, 16.7%), incomplete expansion (n=1, 3.3%), and tumor ingrowth (n=1, 3.3%). The migration rate was significantly higher in the type-B group than in other groups (p=0.038).

Conclusion

Newly designed covered and non-covered metallic stents of a larger diameter are effective for the treatment of colorectal obstruction. The migration rate of covered stents with flaring is higher than that of other types. For evaluation of the ideal stent configuration for the relief of colorectal obstruction, a clinical study involving a larger patient group is warranted.  相似文献   
232.

Objective

To evaluate the radiographic and MR appearance of idiopathic synovial osteochondromatosis of the hip.

Materials and Methods

Radiographs and MR images of 15 patients with idiopathic synovial osteochondromatosis of the hip were assessed. The former were analysed in terms of the presence of 1) juxta-articular calcified and/ or ossified bodies, 2) osteophytes, 3) bone erosion, 4) juxta-articular osteopenia, and 5) joint space narrowing, while for the latter, analysis focused on 1) the configuration of intra-articular bodies, 2) bone erosion, 3) synovial thickening, 4) conglomeration of intra-articular bodies, and 5) extra-articular extension.

Results

At hip radiography, juxta-articular calcified and/ or ossified bodies were seen in 12 of the 15 patients (80%), bone erosion in eight (53%), osteophytes in seven (47%), juxta-articular osteopenia in five (33%) and joint space narrowing in five (33%). In eight patients (53%), MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, and areas of iso-intensity at T1WI and hyperintensity at T2WI. In three (20%), intra-articular bodies of focal low signal intensity and areas of hyperintensity at all pulse sequences were observed, with areas of iso-intensity at T1WI and hyperintensity at T2WI, while in four (27%), intra-articular bodies of only focal low signal intensity at all pulse sequences were apparent. Synovial thickening was present in 13 patients (87%), bone erosion in 11 (73%), conglomeration of the intra-articular bodies in 11 (73%), and an extra-articular herniation sac in six (40%).

Conclusion

The most common radiographic finding of synovial osteochondromatosis of the hip was the presence of juxta-articular calcified and/ or ossified bodies. MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, with areas of iso-intensity at T1WI and hyperintensity at T2WI. In addition, the presence of an extra-articular herniation sac was not uncommon.  相似文献   
233.
PURPOSE: To assess whether coaxial placement of uncovered and covered expandable nitinol stents overcomes the disadvantages of the increased migration rate seen with covered stents and the tumor ingrowth seen in uncovered stents in the treatment of malignant gastric outlet obstructions. MATERIALS AND METHODS: Two types of expandable nitinol stent were designed: an uncovered stent and a covered stent. Under fluoroscopic guidance, the uncovered and covered stents were placed coaxially with complete overlap in 39 consecutive patients with malignant gastric outlet obstruction caused by stomach cancer. Food intake capacity was graded on a scale of 0-4. Stent patency rate was estimated by the Kaplan-Meier method. RESULTS: Technical success rate was 97% (38 of 39 patients). After stent placement, food intake capacity improved at least one grade in 36 patients. Stent migration occurred in three patients (8%), that is, partial (n = 2) or complete (n = 1) upward migration of the inner covered stent into the stomach. Two of these patients were treated by placement of an additional covered stent. During the mean follow-up period of 134 days (range, 15-569 d), 10 patients developed recurrent symptoms of obstruction with tumor overgrowth being the most common cause. Nine underwent placement of an additional covered stent with good results. The median period of primary stent patency was 157 days (mean, 278 d). The 30-, 60-, and 180-day patency rates were 97%, 91%, and 39%, respectively. Four patients (10%) died within 1 month after the procedure. CONCLUSION: Coaxial stent placement technique seems to contribute to decreasing the migration rate of the stent and decrease the rate of recurrent obstruction by preventing or delaying tumor ingrowth.  相似文献   
234.
Air-trapping zone surrounding sclerosing hemangioma of the lung   总被引:17,自引:0,他引:17  
We present two cases of sclerosing hemangioma of the lung with a peculiar radiologic finding: an air-trapping zone surrounding the tumor. On microscopic examinations, the tumor was of the hemangiomatous subtype, and the radiolucent zone corresponded to enlarged alveoli with septal destruction. A possible mechanism in the production of an air-trapping zone around a sclerosing hemangioma is bleeding from the highly vascular tumor followed by expectoration in communication with an airway. We reviewed the literature on the air meniscus sign in sclerosing hemangioma and concluded that although it is not a common finding, it could be of help in the confident diagnosis of sclerosing hemangioma and in differentiating it from other benign tumors of the lung.  相似文献   
235.
Kim HJ  Higashimori T  Park SY  Choi H  Dong J  Kim YJ  Noh HL  Cho YR  Cline G  Kim YB  Kim JK 《Diabetes》2004,53(4):1060-1067
The circulating level of the inflammatory cytokine interleukin (IL)-6 is elevated in various insulin-resistant states including type 2 diabetes, obesity, cancer, and HIV-associated lipodystrophy. To determine the role of IL-6 in the development of insulin resistance, we examined the effects of IL-6 treatment on whole-body insulin action and glucose metabolism in vivo during hyperinsulinemic-euglycemic clamps in awake mice. Pretreatment of IL-6 blunted insulin's ability to suppress hepatic glucose production and insulin-stimulated insulin receptor substrate (IRS)-2-associated phosphatidylinositol (PI) 3-kinase activity in liver. Acute IL-6 treatment also reduced insulin-stimulated glucose uptake in skeletal muscle, and this was associated with defects in insulin-stimulated IRS-1-associated PI 3-kinase activity and increases in fatty acyl-CoA levels in skeletal muscle. In contrast, we found that co-treatment of IL-10, a predominantly anti-inflammatory cytokine, prevented IL-6-induced defects in hepatic insulin action and signaling activity. Additionally, IL-10 co-treatment protected skeletal muscle from IL-6 and lipid-induced defects in insulin action and signaling activity, and these effects were associated with decreases in intramuscular fatty acyl-CoA levels. This is the first study to demonstrate that inflammatory cytokines IL-6 and IL-10 alter hepatic and skeletal muscle insulin action in vivo, and the mechanism may involve cytokine-induced alteration in intracellular fat contents. These findings implicate an important role of inflammatory cytokines in the pathogenesis of insulin resistance.  相似文献   
236.
237.
We considered performing living donor liver transplantation (LDLT) in a larger-size recipient. When the recipient was large-sized, or when the donor liver was severely steatotic or had a right-to-left volume discrepancy. We devised dual living donor liver transplantation (DLDLT) to make up for graft size insufficiency and to secure the donor's safety. However, portal vein thrombosis (PVT) presented a challenge for DLDLT because of the need for intact right and left portal veins for the implantation of both liver grafts. Our 52-year-old male patient with hepatitis B cirrhosis had suffered from repeated esophageal and gastric variceal bleeding and underwent 2 trials of a transjugular intrahepatic portosystemic shunt (TIPS). He developed TIPS occlusion and PVT involving the area just above the spleno-mesenteric confluence to the right and left PV. Also, the right PV orifice was destructed and difficult to isolate because of severe periportal inflammation and neointima growth in the TIPS mesh. The patient's two sons were inadequate for donation because of right-to-left volume discrepancy. Therefore, DLDLT using 2 left lobes was necessary to compensate for graft-size insufficiency and to secure donor safety, and we substituted an intact umbilical portion of recipient's left PV for the destroyed right PV. The patient recovered well, and liver function has been normal for more than a year. In conclusion, the umbilical portion of recipient's left PV can be a useful vascular substitute for the reconstruction of a thrombosed main portal branch in DLDLT.  相似文献   
238.
The purpose of this study is to present the surgical outcome of endoscopic carpal tunnel release (ECTR) for the treatment of carpal tunnel syndrome (CTS). One hundred and thirty-one procedures (36 right hands, 33 left hands and 31 bilateral hands) of single portal ECTR were performed upon 100 patients (age range: 36-77 years, mean age: 52.9 years; 98 women and 2 men) with electrodiagnostically proven CTS for 2.5 years from 2001. Preoperative clinical severity and results of electrodiagnostic studies were compared with surgical outcomes at the minimal 3-month postoperative period. Among 131 cases 125 (95.4 %) with complete or significant relief of symptoms were satisfied and 6 (4.6 %) with partial or no relief of symptoms were dissatisfied. There were 2 cases of major complications (one with ulnar nerve injury and the other with ulnar artery injury) that developed in our early experience of ECTR and 1 case of recurrence. The grade of electrodiagnostic abnormalities was associated with surgical outcome but there was no statistical significance between them. The severity of clinical findings, age at onset and symptom duration were not correlated with surgical outcome. In conclusion, ECTR surgery was effective in relieving the symptoms of CTS with a low complication rate after the learning curve period. Thus, ECTR can be an alternative to the traditional open surgery and can be the first procedure for CTS with several advantages over open methods.  相似文献   
239.

Background

The transosseous-equivalent (TOE) repair of the rotator cuff tears was invented to make up for several shortcomings of the double-row (DR) repair. However, no studies have compared the clinical aspects of the DR repair and the TOE technique, supporting the superior results of the TOE technique over the DR repair, including the benefit of minimizing surgical steps. We asked whether differences existed between the two repairs regarding clinical outcomes, time and costs.

Materials and methods

Subjects included 55 using the DR repair and 119 using the TOE repair for the medium to large sized rotator cuff tears. Clinical outcomes were measured with a Visual Analog Scale, American Shoulder and Elbow Surgeons score, Constant score, and shoulder strength. For practical aspects, operative time and number of suture anchors used for the medial and lateral rows were compared.

Results

Both repairs brought substantial improvements in pain and function. However, significant differences were not detected between the repairs in all the clinical measurements. Regarding operative time and costs, in the medium size tears, a statistical difference was found only in the anchors used for the lateral row. In the large size tears, the DR repair required more operation time than the TOE repair, while the TOE repair used more anchors for the lateral row.

Conclusion

This study failed to demonstrate clinical differences between the techniques. However, when stratifying rotator cuff tears according to the tear sizes, significant differences were found in operative time and cost: the DR repair had the advantage of cost effectiveness by saving anchors for the lateral row, while the TOE repair required less operative time with more anchors used for the lateral row in the large size tears. This finding provides evidence to support the use of the TOE repair to reduce surgical steps.  相似文献   
240.
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