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   6318篇
  免费   541篇
  国内免费   78篇
耳鼻咽喉   89篇
儿科学   182篇
妇产科学   191篇
基础医学   756篇
口腔科学   69篇
临床医学   650篇
内科学   1375篇
皮肤病学   85篇
神经病学   652篇
特种医学   156篇
外科学   947篇
综合类   166篇
一般理论   5篇
预防医学   699篇
眼科学   277篇
药学   454篇
中国医学   3篇
肿瘤学   181篇
  2023年   27篇
  2022年   29篇
  2021年   91篇
  2020年   44篇
  2019年   96篇
  2018年   99篇
  2017年   94篇
  2016年   92篇
  2015年   95篇
  2014年   150篇
  2013年   284篇
  2012年   320篇
  2011年   406篇
  2010年   224篇
  2009年   228篇
  2008年   384篇
  2007年   405篇
  2006年   389篇
  2005年   437篇
  2004年   430篇
  2003年   370篇
  2002年   361篇
  2001年   66篇
  2000年   40篇
  1999年   60篇
  1998年   94篇
  1997年   82篇
  1996年   83篇
  1995年   51篇
  1994年   74篇
  1993年   57篇
  1992年   36篇
  1991年   43篇
  1990年   42篇
  1989年   32篇
  1988年   30篇
  1987年   25篇
  1986年   36篇
  1985年   45篇
  1984年   49篇
  1983年   50篇
  1982年   63篇
  1981年   51篇
  1980年   67篇
  1979年   35篇
  1978年   45篇
  1977年   29篇
  1976年   38篇
  1974年   37篇
  1973年   25篇
排序方式: 共有6937条查询结果,搜索用时 15 毫秒
101.
Alcohol-induced chronic pancreatitis involving the head of pancreas may have profound effects on the hepatobiliary system. The natural history, complications, and management of the syndrome are presented, using selected cases to emphasize important features. Chronic pancreatitis can cause mechanical obstruction to both the distal common bile duct and the proximal pancreatic duct. In the common bile duct this will result in proximal dilatation above the stenosis with bile stasis. Possible sequelae are ascending cholangitis, cholecystitis, biliary calculi formation, and secondary biliary cirrhosis. The mechanical effects of stricture of the proximal pancreatic duct may exacerbate pancreatic dysfunction. The clinicopathological spectrum of chronic pancreatitis with biliary obstruction encompasses three clinical types–"transient,""recurrent." and "persistent." The widespread effects of the syndrome are evident from the involvement of pancreas, proximal pancreatic duct, papilla of Vater, liver, peripheral biliary tree, common bile duct, gallbladder, and reticuloendothelial system. Essential to management is surgery which should be considered when there is objective evidence of obstruction to the common bile duct. Choledochoduodenostomy is the preferred type of operation. If dilatation is mild and jaundice transient, conservative therapy with careful observation is advocated.  相似文献   
102.
Spontaneous free perforation of the small intestine in Crohn's disease.   总被引:1,自引:0,他引:1  
Spontaneous free perforation of the small intestine is a rare but often dramatic event in the clinical course of Crohn's disease. Fifteen new cases of spontaneous free perforation of the small intestine--nine female patients and six male patients--were discovered in a series of 1000 consecutively evaluated patients with Crohn's disease seen during a period spanning 20 years, for an estimated frequency of 1.5%. Spontaneous free perforation was the presenting clinical feature of Crohn's disease in nine (60%) of the newly discovered cases. Most perforations were located in the ileum rather than in the jejunum, and there were no duodenal free perforations. One patient with extensive intestinal disease presented with concomitant free perforations of the jejunum and ileum, while a second patient had two free ileal perforations that developed independently, separated by about six years. No perforations were the result of a superimposed malignant process, ie, adenocarcinoma or lymphoma. There have been no mortalities, and the subsequent clinical course of these patients has been limited to a minority requiring corticosteroid or immunosuppressive medications, or further surgical resections.  相似文献   
103.
PURPOSE: This study was designed to determine clinical and pathologic variables associated with poor outcome following resection of Stage B colorectal cancer. METHODS: This was a retrospective study of 117 patients with Stage B cancer who underwent curative surgery and survived the postoperative period. Fourteen clinical and pathologic features were studied. Clinical data were extracted from a prospective colorectal cancer database, and histologic slides were retreived and examined by a pathologist blinded as to clinical details and outcome. RESULTS: After a median follow-up period of 8.2 years, bowel obstruction was significantly related to a poor prognosis (log-rank test; P=0.03). Extensive necrosis (P =0.01) and perineural invasion (P = 0.03) were also associated with decreased survival. Vascular invasion was associated with poor long-term outcome in the subgroup of patients with rectal (P =0.07) but not colonic (P =0.57) cancer. Multivariate regression analysis identified both tumor necrosis (P =0.01) and perineural invasion (P =0.03) as independently related to outcome. CONCLUSION: Further study of prognostic indicators might result in an algorithm to distinguish Stage B cases at high risk of tumor recurrence and death. Such patients could be included in future trials of adjuvant therapies.Presented in part at the meeting of the American Gastroenterological Association, Boston, Massachusetts, May 16 to 19, 1993. Published in abstract form in Gastroenterology 1993;104:A432.  相似文献   
104.
Clostridium difficile (CD), specifically its toxins, have been implicated as a risk factor for exacerbation of the inflammatory process in up to 5% of patients with ulcerative colitis or Crohn’s disease. Typical evidence of colonic changes with CD infection, including pseudomembranous exudate, are often not present; however, a severe clinical course may result, including precipitation of toxic colitis and toxic megacolon. Recently, hypervirulent CD strains have been reported raising concern for a more severe disease process in patients with underlying inflammatory bowel disease.Moreover, small bowel involvement or CD enteritis has been increasingly described, usually in those with a history of a prior colectomy or total proctocolectomy for prior severe and extensive inflammatory bowel disease. Finally, refractory or treatment-resistant pouchitis may occur with CD infection.  相似文献   
105.
Adult celiac disease followed by onset of systemic lupus erythematosus   总被引:1,自引:0,他引:1  
BACKGROUND: Celiac disease has been associated with autoimmune disease (eg, autoimmune thyroiditis) and the appearance of different autoantibodies (eg, antidouble-stranded DNA). Conversely, tissue transglutaminase antibodies have been detected in autoimmune disorders, including systemic lupus erythematosus (SLE), but cases of celiac disease with SLE have been only rarely recorded. METHODS: In this study, 246 patients with biopsy-defined celiac disease were evaluated for a prior diagnosis of SLE on the basis of American Rheumatological Association-defined clinical and serologic parameters. RESULTS: There were 6 patients with celiac disease and SLE, or 2.4%, including 4 females and 2 males. Their mean age at diagnosis of celiac disease was 44.7 years and SLE 50 years. In all patients, the diagnosis of SLE was established from 2 years to more than 10 years after the diagnosis of celiac disease, with a mean of 5.3 years. The celiac disease in all 6 patients responded to a gluten-free diet with histologic normalization of the small intestinal biopsies. Despite this small bowel biopsy response, SLE appeared later in the clinical course of the celiac disease. CONCLUSIONS: This study suggests that SLE occurs far more frequently in biopsy-defined celiac disease than is currently appreciated, and detection may be more likely if the period of clinical follow-up of the celiac disease is prolonged.  相似文献   
106.
Despite wide use in clinical practice, acupuncture remains a controversial treatment for chronic pain. Our objective was to update an individual patient data meta-analysis to determine the effect size of acupuncture for 4 chronic pain conditions. We searched MEDLINE and the Cochrane Central Registry of Controlled Trials randomized trials published up until December 31, 2015. We included randomized trials of acupuncture needling versus either sham acupuncture or no acupuncture control for nonspecific musculoskeletal pain, osteoarthritis, chronic headache, or shoulder pain. Trials were only included if allocation concealment was unambiguously determined to be adequate. Raw data were obtained from study authors and entered into an individual patient data meta-analysis. The main outcome measures were pain and function. An additional 13 trials were identified, with data received for a total of 20,827 patients from 39 trials. Acupuncture was superior to sham as well as no acupuncture control for each pain condition (all P?<?.001) with differences between groups close to .5 SDs compared with no acupuncture control and close to .2 SDs compared with sham. We also found clear evidence that the effects of acupuncture persist over time with only a small decrease, approximately 15%, in treatment effect at 1 year. In secondary analyses, we found no obvious association between trial outcome and characteristics of acupuncture treatment, but effect sizes of acupuncture were associated with the type of control group, with smaller effects sizes for sham controlled trials that used a penetrating needle for sham, and for trials that had high intensity of intervention in the control arm. We conclude that acupuncture is effective for the treatment of chronic pain, with treatment effects persisting over time. Although factors in addition to the specific effects of needling at correct acupuncture point locations are important contributors to the treatment effect, decreases in pain after acupuncture cannot be explained solely in terms of placebo effects. Variations in the effect size of acupuncture in different trials are driven predominantly by differences in treatments received by the control group rather than by differences in the characteristics of acupuncture treatment.

Perspective

Acupuncture is effective for the treatment of chronic musculoskeletal, headache, and osteoarthritis pain. Treatment effects of acupuncture persist over time and cannot be explained solely in terms of placebo effects. Referral for a course of acupuncture treatment is a reasonable option for a patient with chronic pain.  相似文献   
107.
Background: Preoperative malnutrition is increasingly prevalent in patients undergoing cardiac surgery. Although prealbumin is a widely used indicator of nutrition status, its use in the preoperative assessment of patients undergoing cardiac surgery is not well defined. The purpose of this study is to determine the impact of preoperative prealbumin levels on outcomes after cardiac surgery. Materials and Methods: Data were prospectively gathered from February 2013 to July 2013 on 69 patients undergoing cardiac surgery. Prealbumin levels were obtained within 24 hours of surgery. Patients were divided into 2 groups based on a prealbumin cutoff value of 20 mg/dL. Results: Of the 69 patients, 32 (46.4%) had a preoperative prealbumin ≤20 mg/dL. There was no correlation between prealbumin levels and body mass index (r = ?0.13, P = .28). Likewise, there was no correlation between preoperative albumin and prealbumin levels (r = 0.09, P = .44). Nine of 32 (28.1%) patients with low preoperative prealbumin levels had postoperative infections compared with 2 of 37 (5.4%) patients with high prealbumin levels (P = .010). Patients with low prealbumin levels also had increased risk of postoperative intubation for >12 hours (P = .010). Conclusions: Patients undergoing cardiac surgery with preoperative prealbumin levels of ≤20 mg/dL have an increased risk for postoperative infections and the need for longer mechanical ventilation. If feasible, nutrition optimization of such patients may be considered prior to cardiac surgery.  相似文献   
108.
109.
110.
OBJECTIVES: We sought to determine the prevalence of treatable left ventricular (LV) systolic dysfunction (LVSD) in patients who present with their first noncardiac vascular episode. BACKGROUND: Screening for LV dysfunction in patients who present with their first stroke (cerebrovascular accident), their first transient ischemic attack (TIA) or their first manifestation of peripheral vascular disease (PVD) may represent a golden opportunity to identify treatable LV dysfunction, and so their known high incidence of sudden cardiac death may be reduced. METHODS: Participating in this study were 522 (75%) of 700 consecutive patients (302 patients with stroke, TIA or PVD and 220 age- and gender-matched control subjects). Each underwent a full clinical assessment, 12-lead electrocardiography and two-dimensional echocardiography. Left ventricular dysfunction was defined as LV ejection fraction < or = 40%. RESULTS: Seventy-two (28%) patients with vascular disease and 11 (5.5%) control subjects were found to have LVSD. Twenty-six (28%) stroke patients, 22 (26%) patients with TIA and 24 (31%) patients with PVD had LVSD. Left ventricular systolic dysfunction was symptomatic in 44% of patients and in 35% of control subjects. CONCLUSIONS: Left ventricular systolic dysfunction is five times more common among patients with stroke, TIA and PVD than among age- and gender-matched control subjects. Asymptomatic LVSD is more common than symptomatic LVSD in these patients. These findings suggest that routine screening of all patients with noncardiac vascular episodes for LVSD should now be considered. Future studies should investigate whether identifying and treating LVSD in these patients would reduce their known high rate of cardiac death.  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