首页 | 官方网站   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   10664篇
  免费   856篇
  国内免费   110篇
医药卫生   11630篇
  2023年   53篇
  2022年   66篇
  2021年   232篇
  2020年   128篇
  2019年   234篇
  2018年   261篇
  2017年   194篇
  2016年   200篇
  2015年   254篇
  2014年   326篇
  2013年   423篇
  2012年   665篇
  2011年   667篇
  2010年   377篇
  2009年   353篇
  2008年   629篇
  2007年   612篇
  2006年   627篇
  2005年   582篇
  2004年   534篇
  2003年   455篇
  2002年   413篇
  2001年   397篇
  2000年   397篇
  1999年   330篇
  1998年   148篇
  1997年   119篇
  1996年   120篇
  1995年   104篇
  1994年   84篇
  1993年   83篇
  1992年   182篇
  1991年   154篇
  1990年   143篇
  1989年   158篇
  1988年   145篇
  1987年   134篇
  1986年   130篇
  1985年   108篇
  1984年   72篇
  1983年   55篇
  1982年   41篇
  1981年   39篇
  1980年   29篇
  1979年   35篇
  1978年   19篇
  1977年   22篇
  1976年   19篇
  1975年   13篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background: A high level of low-density lipoprotein cholesterol (LDL-C) is a major risk factor for coronary artery disease (CAD). Evidence shows that lowering LDL-C improves the outcomes of patients with CAD. Atorvastatin is an established drug for the treatment of hypercholesterolemia.Objective: The purpose of this open-label, uncontrolled, prospective study was to assess the effectiveness of treatment with atorvastatin 10 mg/d for 18 weeks in achieving the target level of LDL-C (<2.6 mmol/L [<100 mg/dL]) established by the National Cholesterol Education Program (NCEP) (United States) for patients with established CAD and hypercholesterolemia.Methods: Chinese patients with CAD, hypercholesterolemia (defined as a baseline LDL-C level between 3.4 and 5.2 mmol/L [131-201 mg/dL]), and body mass index <30 kg/m2 were eligible. Atorvastatin 10 mg/d was given to each patient for 18 weeks. Lipid profiles were checked at 6, 12, and 18 weeks. To assess the extent of the achievement of NCEP LDL-C target levels, patients were categorized into 3 groups retrospectively according to baseline LDL-C level: group 1, 3.4 to 4.0 mmol/L (131-154 mg/dL); group 2, 4.01 to 4.6 mmol/L (155-178 mg/dL); and group 3, 4.61 to 5.2 mmol/L (179-201 mg/dL).Results: A total of 63 patients (50 men, 13 women; mean age, 64.3 years) were enrolled. Significant decreases in total cholesterol (31.3% at week 18), LDL-C (42.9% at week 18), and triglycerides (21.8% at week 18) from baseline levels were found at 6, 12, and 18 weeks of treatment (P < 0.001 for all). The changes in high-density lipoprotein cholesterol levels were nonsignificant. In group 1, 83.3% of patients met the target level of LDL-C; group 2, 87.5%; group 3, 37.5%; groups 1 and 2 combined, 85.2%. Atorvastatin 10 mg/d was well tolerated. Clinical adverse events were mild and transient; no severe adverse events were reported. One patient (1.6%) developed an elevated alanine aminotransferase level and withdrew. Sixty-two of 63 patients (98.4%) completed the study.Conclusions: In this group of Chinese patients with CAD and hypercholesterolemia treated with atorvastatin 10 mg/d for 18 weeks, 85.2% of patients with a baseline LDL-C level of 3.4 to 4.6 mmol/L achieved the NCEP target LDL-C level of <2.6 mmol/L, suggesting that atorvastatin 10 mg/d is efficacious in preventing secondary CAD.  相似文献   
992.
1. Plasma and urine free and total carnitine and acylcarnitine levels were assayed in 12 control subjects and 20 chronic alcoholics with fatty liver. Although the alcoholics had a wider range of values than the controls, there was no significant difference between the two groups. 2. Hepatic free and total carnitine and long- and short-chain acylcarnitines were assayed by a radioenzymatic method in samples from seven control subjects and seven alcoholics. No significant differences in any of the indices were noted between the patient and control groups and it was concluded that carnitine deficiency did not contribute to alcoholic fatty liver in patients without cirrhosis. 3. Skeletal muscle free and total carnitine and long- and short-chain acylcarnitines were assayed in eight alcoholics and seven control subjects. The alcoholics had significantly higher total and free carnitine levels. It is suggested that this reflects a selective enrichment of the biopsy sample with type I carnitine-rich fibres due to the type II fibre atrophy found in approximately half the patients.  相似文献   
993.
The values of procalcitonin (PCT), neopterin, and C-reactive protein (CRP) alone and in combination to differentiate bacterial from viral etiology in patients with lower respiratory tract infections (LRTIs) were evaluated. Sera obtained on the day of hospitalization for LRTI from 139 patients with confirmed bacterial etiology and 128 patients with viral etiology were examined. A further 146 sera from healthy Chinese subjects with no infection were included as controls. The area under the receiver operating characteristic (ROC) curve (area under curve [AUC]) for distinguishing bacterial from viral infections was 0.838 for CRP and 0.770 for PCT (P < 0.05). The AUC for distinguishing viral from bacterial infections was 0.832 for neopterin (P < 0.05). When the markers were used in combination, AUC of ROC (CRP/neopterin) was 0.857, whereas (CRP x PCT)/neopterin was 0.856. Combination of 2 or all 3 of the biomarkers may improve the discriminatory power in delineating bacterial versus viral etiology in LRTI.  相似文献   
994.
BACKGROUND: Unsedated colonoscopy is not required by the Accreditation Council of Graduate Medical Education in the curriculum of GI trainees. OBJECTIVE: We describe our pilot experience with trainee participation in unsedated colonoscopy. DESIGN: A retrospective review of a performance improvement program to provide access to colonoscopy. SETTING: A Veteran's Affair ambulatory care facility that discontinued sedated colonoscopy because of a nursing shortage. PATIENTS: A total of 145 of 483 patients who chose unsedated colonoscopy after both sedated and unsedated options were discussed. INTERVENTIONS: GI fellows performed unsedated colonoscopy under the supervision of the attending physician. MAIN OUTCOME MEASUREMENTS: Cecal intubation rate, patient assessment of the reasons for the choice, the unsedated experience, willingness to have another colonoscopy, and the rate of return for unsedated colonoscopy among eligible patients. RESULTS: Cecal intubation was achieved in 112 of 145 patients. The adjusted success rate (excluding inadequate bowel preparation and an obstructing lesion) was 81%. The most frequently acknowledged reason for the choice was the ability to communicate with the colonoscopist. Eighty-six patients reported a good experience and were likely to accept another unsedated colonoscopy. To date, all 8 patients eligible for 3-year follow-up successfully completed another unsedated examination. LIMITATION: An uncontrolled, nonrandomized review in predominantly male older veterans. CONCLUSIONS: An unsedated colonoscopy might be acceptable to some populations, particularly when communication with clinicians and procedural convenience are highly valued. Involvement of trainees is feasible. Randomized controlled comparisons of sedated and unsedated options in terms of safety (eg, sedation and procedure-related complications) and cost in settings with and without a nursing shortage deserve to be considered.  相似文献   
995.
996.

Background  

Endorectal ultrasound (ERUS) is an emerging technique for preoperative rectal cancer staging. It is an operator-dependent examination with accuracy closely related to endosonographer experience. In this study, we prospectively analyzed our results of ERUS staging for rectal cancer, aiming to determine its accuracy and to define the learning curve of the procedure.  相似文献   
997.
The histologic subtype of non-small cell lung carcinoma is important in selecting appropriate chemotherapy for patients with advanced disease. As many of these patients are not operative candidates, they are treated medically after biopsy for diagnosis. Inherent limitations of small biopsy samples can make distinguishing poorly differentiated lung adenocarcinoma (ADC) from squamous cell carcinoma (SCC) difficult. The value of histochemical and immunohistochemical markers to help separate poorly differentiated ADC from SCC in resection specimens is well established; however, the optimal use of markers in small tissue samples has only recently been examined and the correlation of marker expression in small tissue samples with histologic subtype determined on resection specimens has not been well documented. We address this issue by examining the expression of 9 markers (p63, TTF1, CK5/6, CK7, 34βE12, Napsin A, mucicarmine, NTRK1, and NTRK2) on 200 cases of ADC and 225 cases of SCC in tissue microarray format to mimic small tissue specimens. The single best marker to separate ADC from SCC is p63 (for SCC: sensitivity 84%, specificity 85%). Logistic regression analysis identifies p63, TTF1, CK5/6, CK7, Napsin A, and mucicarmine as the optimal panel to separate ADC from SCC. Reduction of the panel to p63, TTF1, CK5/6, and CK7 is marginally less effective but may be the best compromise when tissue is limited. We present an algorithm for the stepwise application of p63, TTF1, CK5/6, CK7, Napsin A, and mucicarmine in situations in which separation of ADC from SCC in small specimens cannot be accomplished by morphology alone.  相似文献   
998.
Background : The long‐term prognostic implication of post‐procedural hematocrit drops in patients undergoing cardiac catheterization outside the clinical trial setting is not well defined. Methods : Data was prospectively collected from 12,661 patients undergoing diagnostic or interventional cardiac catheterization between July 1998 and July 2006. Patients were divided into three cohorts based upon the degree of hematocrit change: drop greater than 6, drop between 3 and 6, and drop less than 3. In‐hospital major adverse events, 30‐day mortality, and long‐term all‐cause mortality were recorded. Results : Patients with larger reductions in hematocrit were more likely to be older, female, and have a higher baseline hematocrit, present with acute myocardial infarction, develop cardiogenic shock, require emergent catheterization, develop retroperitoneal bleeds and large hematomas, receive transfusions, have longer index hospitalizations, develop subacute stent thrombosis, and have higher 30‐day and long‐term mortality. An increase in long‐term mortality was observed with progressive hematocrit drop. This finding is largely driven by early (30 day) mortality, as trends were no longer significant after rezeroing mortality. Hematocrit drop was not an independent risk factor for 30‐day mortality. Transfusion and low baseline hematocrit were identified as independent predictors of near and long‐term mortality. Conclusions : Periprocedural bleeding, defined by hematocrit drop, is associated with increased near‐term and long‐term mortality in patients undergoing diagnostic and therapeutic cardiac catheterization procedures. Long‐term mortality is largely driven by up front 30‐day mortality. Hematocrit drop was not an independent predictor for near‐term mortality. Transfusion and low baseline hematocrit were independent predictors for near and long‐term mortality. © 2009 Wiley‐Liss, Inc.  相似文献   
999.
1000.
Ho AM  Cheung BK  Stadlin A 《Addictive behaviors》2011,36(12):1361-1364
We compared cold-pain responses among male current opioid users with and without concurrent benzodiazepine use, long-term ex-users, and healthy controls. Forty-eight current opioid users (14 concurrently using benzodiazepines), 34 ex-users (abstinent for ≥1 y) and 63 controls received cold-pressor tests. Pain threshold (first reporting pain) and pain tolerance (total immersion time) were recorded. Pain thresholds were similar in ex-users and current users; pain tolerance was similar in ex-users and controls. Net pain tolerance (endurance) in ex-users was intermediate between the other two groups. Current users showed higher pain threshold and shorter pain tolerance than controls (p<0.05). Current users not co-using benzodiazepines showed the lowest pain tolerance and net pain tolerance, and differed significantly from controls, ex-users, and current users co-using benzodiazepines (p<0.05). Neuroticism was higher in current users than in the other two groups (p<0.001), extraversion marginally lower (p<0.05); net pain tolerance differences remained significant after controlling for these. Benzodiazepine use modulates pain tolerance in opioid users. Pain responses altered by opioid use may partially recover with abstinence.  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-23

京公网安备 11010802026262号