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   193178篇
  免费   1626篇
  国内免费   57篇
耳鼻咽喉   2100篇
儿科学   7160篇
妇产科学   4146篇
基础医学   18713篇
口腔科学   1704篇
临床医学   13418篇
内科学   34600篇
皮肤病学   872篇
神经病学   18334篇
特种医学   9268篇
外科学   30077篇
综合类   2366篇
一般理论   4篇
预防医学   19292篇
眼科学   3319篇
药学   11914篇
中国医学   674篇
肿瘤学   16900篇
  2023年   88篇
  2022年   196篇
  2021年   400篇
  2020年   204篇
  2019年   368篇
  2018年   22494篇
  2017年   17708篇
  2016年   19890篇
  2015年   1310篇
  2014年   1485篇
  2013年   1768篇
  2012年   8117篇
  2011年   22373篇
  2010年   19543篇
  2009年   11827篇
  2008年   20369篇
  2007年   22883篇
  2006年   1882篇
  2005年   3405篇
  2004年   4704篇
  2003年   5654篇
  2002年   3555篇
  2001年   735篇
  2000年   907篇
  1999年   468篇
  1998年   305篇
  1997年   232篇
  1996年   106篇
  1995年   123篇
  1994年   119篇
  1993年   74篇
  1992年   66篇
  1991年   104篇
  1990年   164篇
  1989年   97篇
  1988年   72篇
  1987年   60篇
  1986年   37篇
  1985年   52篇
  1984年   35篇
  1983年   40篇
  1982年   48篇
  1981年   34篇
  1980年   62篇
  1978年   34篇
  1975年   34篇
  1974年   32篇
  1938年   63篇
  1932年   59篇
  1930年   49篇
排序方式: 共有10000条查询结果,搜索用时 814 毫秒
121.

Background  

Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure.  相似文献   
122.
We examined the clinical and radiographic results of 93 patients affected by knee arthritis or osteonecrosis subjected to unilateral cementless mobile-bearing total knee arthroplasty with the LCS prothesis (Depuy/Johnson & Johnson). The mean follow-up was 9.5 years (range, 7–12 years). Clinical evaluation was performed using the Knee Society rating system, while radiographic evaluation was done according to the Knee Society roentgenographic system. At the latest follow-up, the mean knee score was 87 points: the functional score improved from 40 to 90. Radiolucent lines were small and not progressive. The implant survival at 12 years was 88%. Six knees (7%) required revision for implant-related problems. We conclude that the mobile-bearing prosthesis is a successful device even at long-term follow-up.  相似文献   
123.

Background  

Skin and soft tissue infections are increasingly prevalent clinical problems, and it is important for health care practitioners to be well trained in how to treat skin abscesses. A realistic model of abscess incision and drainage will allow trainees to learn and practice this basic physician procedure.  相似文献   
124.
The objective of this study is to compare the effects of three different anesthetic combinations on the electroretinogram in the same animals under similar laboratory conditions. Thiopental–isoflurane (TI), medetomidine–ketamine (MK), and xylazine–ketamine (XK) were used on each of 12 healthy miniature schnauzer dogs (MS) with a period of at least 3 weeks in between subsequent anesthesia protocols, using the Dog Standard Protocol. The scotopic ERGs consisted of scotopic low stimulus strength (S) responses designated S1, S2, S3, S4, and S5, at 1, 5, 10, 15, and 20 min after dark adaptation, respectively, and scotopic standard stimulus strength (S-ST) responses. The photopic ERGs consisted of a photopic single flash (P) response and 31 Hz flicker (P-FL) responses. For S-ST (2.5 cd s/m2), the amplitude of the a-wave using TI was significantly lower than that using MK (adjusted P = 0.05) and XK (adjusted P = 0.03), and the implicit time of the a-wave was significantly shorter than that using MK (adjusted P = 0.04). For P (2.5 cd s/m2), the amplitude of the b-wave using XK was significantly higher than that using MK (adjusted P = 0.01). The implicit times of the b-wave using TI was significantly longer and shorter than that of MK for S1, S2 and P-FL and for S4 and S-ST, respectively, and than that of XK for S2 and P-FL and for S5 and S-ST, respectively. The results of the present study showed that TI affected both the amplitude and the implicit time of the a-wave for S-ST and the implicit time of the b-wave relatively more so than was the case when using XK or MK. Therefore, it appears that either XK or MK could be advantageous to use rather than TI for clinical studies.  相似文献   
125.
Conclusion  We would like to stress that we do not necessarily consider AC for SPECT MPI to be unfeasible or unworthy of scientific pursuit; indeed, a great deal of creative scientific effort has been poured into this area of investigation over the past 3 decades, and much of it has contributed to a better understanding of the physics, as well as the clinical aspects, of our field. However, the great variety of available AC hardware and software “flavors,” the historical pattern of commercial release of insufficiently validated AC implementations, and the increasingly clouded health care reimbursement horizon may have created an environment where the envisioned users of the technology have been desensitized and discouraged from expecting it to ever come to fruition in a standardized, validated, and costeffective form. It has been reported as recently as 2005 that the “entire base of SPECT cameras has only 5% of systems with attenuation correction.”8 Perhaps the reports of AC’s demise are exaggerated, but it certainly seems as if the people have spoken and, after readying themselves for the wolf one too many times, have come to the conclusion that “the future (of AC) ain’t what it used to be” . . .at least not yet.  相似文献   
126.
Survival after resection of colorectal liver metastases has traditionally been associated with clinicopathologic factors. We sought to investigate whether echogenicity of colorectal liver metastasis as assessed by intraoperative ultrasound (IOUS) was a prognostic factor after hepatic resection. Prospective data on tumor IOUS appearance were collected in 84 patients who underwent hepatic resection for colorectal liver metastasis. Images were digitally recorded, blindly reviewed, and scored for echogenicity (hypo-, iso-, or hyperechoic). The median tumor number was 1 and the median tumor size was 5.0 cm. At the time of surgery, the IOUS appearance of the colorectal liver metastases were hypoechoic in 35 (41.7%) patients, isoechoic in 37 (44.0%) patients, and hyperechoic in 12 (14.3%) patients. Traditional clinicopathologic prognostic factors were similarly distributed among the three echogenicity groups (all p > 0.05). Patients with a hypoechoic lesion had a significantly shorter median survival (30.2 months) compared with patients who had either an isoechoic (53.2 months) or hyperechoic (42.3 months) lesion (p = 0.005). The 5-year survival after hepatic resection of colorectal liver metastasis was also associated with the echogenic appearance of the lesion (hypoechoic 14.4 vs isoechoic 37.4 vs hyperechoic 46.2%) (p < 0.05). Intraoperative ultrasound echogenicity should be considered a prognostic factor after hepatic resection of metastatic colorectal cancer. This study was presented at the 47th annual meeting of The Society for Surgery of the Alimentary Tract, Los Angeles, CA, USA, 22 May 2006.  相似文献   
127.
Laparoscopic colectomy is a difficult procedure with a long learning curve. We describe in this study our technique for right- and left-sided laparoscopic medial-to-lateral colectomy. The medial approach involves division of the vascular pedicle first, followed by mobilization of the mesentery toward the abdominal wall, and finally freeing of the colon along the white line of Toldt. This approach allows immediate identification of the plane between the mesocolon and the retroperitoneum and renders the dissection fast and safe. Our series of 50 consecutive laparoscopic colectomies supports this concept. We believe that surgeons familiar with this technique will have an important tool in their armamentarium to circumvent some of the challenges of laparoscopic colectomy.  相似文献   
128.
Gastroesophageal reflux disease (GERD) is a common disease and can be successfully treated by laparoscopic fundoplication. This article describes the technique of laparoscopic surgery for GERD with a focus on operative pitfalls.  相似文献   
129.
Management of upper gastrointestinal bleeding because of erosion of vessels by esophageal cancer may be challenging. We present herein the angiographic images of a 49-year-old patient who was admitted with massive bleeding from a tumor-eroded inferior thyroid artery. Attempts to control the bleeding by means of flexible endoscopy and insertion of a Sengstaken–Blakemore tube had failed. The diagnosis was impressively demonstrated by multislice computed tomography with intravenous contrast in the arterial phase and multiplanar reconstructions (computed tomography angiography) and by digital subtraction angiography. The bleeding was successfully treated with superselective catheterization and coiling of the eroded vessel.  相似文献   
130.
Internal hernia, the protrusion of a viscus through a peritoneal or mesenteric aperture, is a rare cause of small bowel obstruction. We report the clinical presentation, surgical management, and outcomes of one of the largest series of nonbariatric internal hernias. Ten-year retrospective review of patients at our institution yielded 49 cases of internal hernias. Majority of patients presented with symptoms of acute (75%) or intermittent (22%) small bowel obstruction. While 16% of CT scans were suspicious for internal hernia, in no cases the preoperative diagnosis of internal hernia was made. The most frequent internal hernias were transmesenteric (57.0%) and 34 hernias (69%) were caused by previous surgery. All internal hernias were reduced and the defects were repaired. Compromised bowel was present in 22 cases and 11 patients underwent small bowel resection. The mean postoperative hospitalization was 10.9 days. The overall mortality rate from our series is 2%, and the morbidity rate is 12%. Transmesenteric hernias, as complications of previous surgeries, are the most prevalent internal hernias. Preoperative diagnosis of internal hernia is extremely difficult because of the nonspecific clinical presentation. However, if discovered promptly, internal hernias can be repaired with acceptable morbidity and mortality. Poster presentation at Digestive Disease Week, May 22, 2006, Los Angeles, California, USA.  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