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   4032篇
  免费   393篇
  国内免费   6篇
耳鼻咽喉   51篇
儿科学   178篇
妇产科学   64篇
基础医学   648篇
口腔科学   58篇
临床医学   462篇
内科学   829篇
皮肤病学   35篇
神经病学   254篇
特种医学   65篇
外科学   523篇
综合类   81篇
一般理论   13篇
预防医学   434篇
眼科学   40篇
药学   242篇
中国医学   3篇
肿瘤学   451篇
  2023年   24篇
  2022年   30篇
  2021年   89篇
  2020年   49篇
  2019年   89篇
  2018年   74篇
  2017年   64篇
  2016年   63篇
  2015年   82篇
  2014年   98篇
  2013年   154篇
  2012年   228篇
  2011年   216篇
  2010年   124篇
  2009年   132篇
  2008年   184篇
  2007年   201篇
  2006年   179篇
  2005年   167篇
  2004年   172篇
  2003年   164篇
  2002年   136篇
  2001年   126篇
  2000年   178篇
  1999年   125篇
  1998年   51篇
  1997年   45篇
  1996年   38篇
  1995年   39篇
  1994年   57篇
  1993年   45篇
  1992年   86篇
  1991年   93篇
  1990年   90篇
  1989年   75篇
  1988年   58篇
  1987年   57篇
  1986年   61篇
  1985年   47篇
  1984年   40篇
  1983年   33篇
  1982年   28篇
  1981年   25篇
  1979年   30篇
  1978年   19篇
  1977年   23篇
  1971年   20篇
  1969年   25篇
  1968年   26篇
  1966年   21篇
排序方式: 共有4431条查询结果,搜索用时 15 毫秒
51.
Eighteen patients with major burns (mean total body surface area burned was 49% and mean total body surface area with full-thickness burns was 38%) had cultured epithelial autografts applied to 2% to 35% of the body surface area. In six patients successful "take" of greater than 65% occurred, and in 12 patients less than 40% "take" occurred. Most wounds underwent early excision to subcutaneous fat or fascia, and the wounds of 16 patients had been treated previously with homograft. Cultured epithelial autografts were covered with either single or multilayered dressings. Perioperative wound cultures showed that all patients had microorganisms, and appropriate perioperative antibiotic coverage of Staphylococcus epidermidis and Pseudomonas aeruginosa was noted less frequently in the poor take group, which may have influenced subsequent cultured epithelial allograft take. Adherence and stability of cultured epithelial allografts lag behind adherence and stability of meshed split-thickness autograft. The anterior trunk and thighs are the best recipient sites. The number of autograft harvests that were required to close wounds and the length of hospital stay were not significantly decreased by the use of cultured epithelial allografts as compared with comparable full-thickness burns that were treated previously without cultured epithelial allografts. Presently, grafting with cultured epithelial allografts is an adjunct but not an alternative to conventional burn-wound coverage with split-thickness autograft, because engraftment is inconsistent.  相似文献   
52.
53.
54.
Though increasing attention is being paid to psychological aspects of multiple sclerosis, much research continues to examine patients as differing in quantity rather than quality of psychological abnormality or response. Cluster analysis was used to identify distinctive psychological profiles in a large sample of patients with multiple sclerosis. It employed three measures, carefully chosen to capture the main responses historically observed in multiple sclerosis. These measures were (1) the patient's physical disability-impairment, assessed by a neurologist; (2) physical disability-impairment as perceived and reported by the patient; and (3) self-reported psychological well-being (or distress) independent of physical signs and symptoms. The optimal solution from the cluster analysis separated the 99 patients into 10 clusters, which were collapsed into four profiles, consistent with the labels "depression," "denial," "exaggerated somatic," and "severity-related." These data give strong empirical support to the existence of discrete and distinctive coping styles in multiple sclerosis.  相似文献   
55.
The Age/Sex Register: estimation of the practice population   总被引:2,自引:0,他引:2  
Determination of the number of patients served by a family practice is important for health services delivery and research. A sound estimate of the practice population should enhance the patient management responsibilities of the family physician. This methodology uses the Age/Sex Register to provide a series of estimations of a "teaching" unit population. Results of a sample survey indicate that 21.3% of "inactive patients" (those who have not received services from the practice in two years) still consider themselves under the care of the practice. Replication of this approach is suggested for other practices to improve planning and resource allocation.  相似文献   
56.
PURPOSE: The purpose of this research was to examine the diagnostic and prognostic significance of elevated serum insulin-like growth factor binding protein (IGFBP)-2 levels in women with ovarian cancer from diagnosis through treatment to relapse or remission. EXPERIMENTAL DESIGN: Serum collected pre- and postoperatively in women newly diagnosed with ovarian cancer, during adjuvant chemotherapy cycles, at 6 months follow-up and at relapse was analyzed for IGFBP-2. Control serum was from women undergoing pelvic or abdominal surgery for benign ovarian disease or nonovarian pathology. RESULTS: IGFBP-2 at diagnosis was significantly elevated (P < 0.0001) in women with ovarian cancer (887 +/- 62 ng/ml) compared with benign controls (337 +/- 25 ng/ml), and women undergoing nonovarian surgery (439 +/- 49 ng/ml) and correlated positively with tumor stage and cellular differentiation but not with CA125. Unexpectedly, IGFBP-2 levels increased additionally 1-week postoperatively in ovarian cancer patients (1581 +/- 90 ng/ml; P = 0.0027) as well as controls (977 +/- 95 ng/ml; P < 0.0001) and was higher in women who had suboptimal debulking compared with optimal debulking of their tumor. IGFBP-2 levels returned to normal in women without evidence of progressive disease, but remained significantly elevated in women who later relapsed. Patients with IGFBP-2 levels in the highest tertile at diagnosis had a significantly shorter progression-free interval and overall survival. CONCLUSION: In ovarian cancer IGFBP-2 is elevated at diagnosis, and corresponds to stage and histology with patients in the highest tertile of IGFBP-2 more likely to relapse and have a poorer outlook. Identification of these patients at diagnosis may allow more individualized, aggressive adjuvant treatment and follow-up, and IGFBP-2 may therefore be an important additional prognostic marker in this disease.  相似文献   
57.
BACKGROUND: The impact of acute rejection, immunosuppression, and infection, specifically cytomegalovirus infection, on the development of chronic rejection in the cardiac allograft, has been the subject of a large number of investigations. One of the difficulties in finding associations has been the marked immunologic heterogeneity of the patient population coupled with the lack of the ability to HLA match. Furthermore, the ideal animal model, which duplicates as well as controls for this immunologic heterogeneity, is lacking. METHODS: To try to simulate differences in HLA matching, immunosuppression regiments and cytomegalovirus infection, heterotopic heart transplantation was performed in two separate, complete MHC mismatch, rat strain combinations (WF-LEW, BN-LEW) requiring chronic immunosuppression and employing four separate immunosuppression/infection protocols. Animals were followed for 6 months, killed, and rejection and vascular changes were scored blinded to the group. RESULTS: The mean vascular and acute rejection scores were not significantly different between treatment regiments for either specific strain combination. There was a trend for the subtherapeutic groups to have higher vascular scores. Overall, there were no significant differences in vascular scores between the WF-LEW and BN-LEW groups (1.25+/-0.18 vs. 1.13+/-0.20, P=NS). Similar numbers of WF-LEW and BN-LEW exhibited cellular infiltration and necrosis of the allograft, but the intensity of the response (rejection score) was more severe in the WF-LEW combination (4.54+/-0.22 vs. 3.92+/-0.21, P=0.052) when limiting the analysis to those with myocyte necrosis. There was no significant correlation between acute rejection and vascular lesion severity in the WF-LEW combination (r=0.22, P=NS) but a high correlation between these parameters in the BN-LEW combination (r=0.74, P<0.0001). CONCLUSIONS: These data suggest that, although acute rejection and chronic rejection are related, MHC matching may influence their interdependence. These data also may explain why the clinical association between acute and chronic rejection is difficult to demonstrate.  相似文献   
58.
Phyllodes tumors of the breast: a review of 32 cases   总被引:2,自引:0,他引:2  
Most general surgeons involved in breast cancer care have limited experience with phyllodes tumors. We analyzed a comprehensive database incorporating 8567 breast cancer cases treated surgically in the Tulsa, Oklahoma, region between 1969 and 1993. This yielded 32 cases of phyllodes tumors (0.37%) in 31 patients. The median age was 57 years (range, 18-91). There were 9 low-grade (28%), 2 intermediate-grade (6%), and 21 high-grade (66%) lesions. Size distribution consisted of 23 (72%) lesions 5 cm or less and 9 (28%) greater than 5 cm (mean, 3; range, 1.2-17.5 cm). Of 137 resected nodes in 13 patients, none were positive for metastatic disease. Surgical management consisted of wide excision or mastectomy. No patients received adjuvant chemoradiation therapy. The disease-free, locoregional disease-free, and overall mean survival rates were 80, 81, and 97 months, respectively. Ten-year disease-free survival (DFS), locoregional disease-free survival (LRDFS), and overall survival (OS) rates were 66, 72, and 55 per cent, respectively. Although there was a tendency toward a higher rate of locoregional recurrences and metastases with high-grade lesions, this was not statistically significant and did not affect DFS, LRDFS, or OS rates. Similarly, size of lesion did not affect DFS, LRDFS, or OS rates. Three patients (9.6%) had metastatic disease at presentation, and a further two (6.4%) developed metastases during follow-up. Overall, nine (28.1%) recurrences developed in eight patients, seven locoregional and two distant. Four patients (12.9%) died with evidence of disease. These findings indicate prolonged survival in this patient population with cystosarcoma phyllodes. Wide local excision of primary and recurrent lesions remains the mainstay of therapy. Neither regional lymph node dissection nor adjuvant chemoradiation adds significant benefit.  相似文献   
59.
BACKGROUND: Mucosal atrophy and bowel shortening are the hallmark of proximal intestinal diversion for extensive necrotizing enterocolitis (NEC) or Thiry-Vella fistulas (TVF), in which the ends of a defunctionalized loop of intestine are exteriorized as stomas. Recombinant human interleukin-11 (rhIL-11) is a pleiotropic cytokine that promotes epithelial regeneration and enhances adaptation after bowel resection. The authors hypothesized that rhIL-11 may prevent mucosal atrophy and bowel shortening in rats with TVF METHODS: After creation of ileal TVF, Sprague-Dawley rats were selected randomly to receive either rhIL-11 or equal volume of 0.1% bovine serum albumin (BSA) subcutaneously daily. On day 14, the TVF were excised and examined morphologically. Enterocyte apoptosis was measured using the TUNEL assay. Mucosal DNA and protein content were measured. RESULTS: Administration of rhIL-11 resulted in a significantly greater weight gain and less shortening of TVF than BSA treatment. TVF from the rhIL-11-treated group showed evidence of hyperplasia and hypertrophy and increased crypt to villus ratio. The BSA group had substantial mucosal atrophy. There was a qualitative decrease in the incidence of apoptosis in the rhIL-11 group. CONCLUSIONS: Recombinant human IL-11 prevents mucosal atrophy and shortening of defunctionalized intestinal loops. It may help reduce the incidence of short gut syndrome in infants with extensive NEC.  相似文献   
60.
OBJECTIVES: We wished to determine whether early rejection after lung transplantation as assessed by surveillance transbronchial biopsy predicts for survival. METHODS: Between 1990 and 1997, 96 consecutive patients had lung transplantation: 89 had a minimum 1-month follow-up. For 71 consecutive patients we have 1-year follow-up and for 69 patients we have the results of the first 3 biopsies. Cytomegalovirus status, bronchiolitis obliterans prevalence, and use of total lymphoid irradiation are noted. Biopsies were done at 1 week and 1, 3, and 6 months. Standard immunosuppression consisted of induction antilymphocyte globulin and high-dose methylprednisolone induction for 1 week and standard maintenance triple therapy. Acute rejection treatment was with pulse methylprednisolone. Bronchiolitis obliterans syndrome was treated with total lymphoid irradiation and a change to tacrolimus and mycophenolate. Blinded grading using International Society for Heart and Lung Transplantation classification was done retrospectively. RESULTS: Survival at 1 month and 1, 2, and 3 years for the 96-patient cohort with 1-year follow-up was 93%, 74%, 62%, and 56%. Survival was not significantly different for subsets with rejection on any combination of the first 3 biopsies (1/3, 2/3, 3/3) or absence of rejection on the first 3 biopsies. Ninety-one positive biopsy results were graded. Eighteen of 71 patients had one or more moderate or severe rejection episodes without survival difference relative to the others. There was no statistically significant association between acute rejection on the first 3 surveillance biopsy results and bronchiolitis obliterans. CONCLUSIONS: Intensive induction and maintenance immunotherapy with surveillance transbronchial biopsies and aggressive treatment of acute rejection is associated with a survival similar to that of patients without early acute rejection. This regimen appears to uncouple the association between early acute rejection and bronchiolitis obliterans. Further study may elucidate this mechanism.  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