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   35608篇
  免费   2342篇
  国内免费   101篇
耳鼻咽喉   507篇
儿科学   858篇
妇产科学   494篇
基础医学   4334篇
口腔科学   475篇
临床医学   3873篇
内科学   7296篇
皮肤病学   431篇
神经病学   3091篇
特种医学   1407篇
外科学   5881篇
综合类   422篇
一般理论   42篇
预防医学   3311篇
眼科学   537篇
药学   2628篇
中国医学   30篇
肿瘤学   2434篇
  2024年   30篇
  2023年   264篇
  2022年   487篇
  2021年   1107篇
  2020年   658篇
  2019年   995篇
  2018年   1193篇
  2017年   834篇
  2016年   852篇
  2015年   1005篇
  2014年   1503篇
  2013年   1960篇
  2012年   2852篇
  2011年   2938篇
  2010年   1540篇
  2009年   1427篇
  2008年   2469篇
  2007年   2410篇
  2006年   2215篇
  2005年   2240篇
  2004年   2102篇
  2003年   1890篇
  2002年   1730篇
  2001年   228篇
  2000年   210篇
  1999年   252篇
  1998年   321篇
  1997年   252篇
  1996年   264篇
  1995年   188篇
  1994年   184篇
  1993年   154篇
  1992年   124篇
  1991年   102篇
  1990年   96篇
  1989年   94篇
  1988年   92篇
  1987年   74篇
  1986年   55篇
  1985年   63篇
  1984年   65篇
  1983年   70篇
  1982年   77篇
  1981年   51篇
  1980年   37篇
  1979年   40篇
  1978年   23篇
  1977年   26篇
  1976年   26篇
  1975年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Placental p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) concentration and cord blood atopic markers were determined in 19 neonates. Increased placental p,p'-DDE was associated with a statistically significant increase in cord plasma interleukin (IL)-13. Furthermore, both cord plasma IL-4/interferon (IFN)-gamma and IL-13/IFN-gamma ratios were significantly positively associated with placental p,p'-DDE concentration.  相似文献   
62.
Prospective studies suggest that tea may protect against cardiovascular disease. A potential mechanism for such an effect involves inhibition of lipid peroxidation by polyphenolic antioxidants derived from tea. Our objective was to determine whether regular ingestion of tea could inhibit in vivo lipid peroxidation. Two controlled intervention studies assessed the effects of regular ingestion of tea on lipid peroxidation determined by measurement of urinary F(2)-isoprostane excretion. Study 1: The effects of 1000 mL/d of green tea and black tea were compared with hot water containing caffeine in 13 subjects with elevated blood pressure using a randomized 3-period (7 d each) crossover design. Study 2: The effects of 1250 mL/d of black tea were compared with hot water in 22 subjects with mildly raised serum total cholesterol concentrations using a randomized 2-period (4 wk each) crossover design. F(2)-isoprostane excretion was not altered after regular ingestion of green tea (273 +/- 48 pmol/mmol creatinine) or black tea (274 +/- 39 pmol/mmol creatinine) in comparison with hot water (263 +/- 47 pmol/mmol creatinine; Study 1), or by regular ingestion of black tea (334 +/- 71 pmol/mmol creatinine) in comparison with hot water (355 +/- 75 pmol/mmol creatinine; Study 2). These results do not support the suggestion that polyphenolic antioxidants derived from tea inhibit in vivo lipid peroxidation.  相似文献   
63.
Background: Anesthetic preconditioning (APC) with sevoflurane reduces myocardial ischemia-reperfusion injury. The authors tested whether two brief exposures to sevoflurane would lead to a better preconditioning state than would a single longer exposure and whether dual exposure to a lower (L) concentration of sevoflurane would achieve an outcome similar to that associated with a single exposure to a higher (H) concentration.

Methods: Langendorff-prepared guinea pig hearts were exposed to 0.4 mm sevoflurane once for 15 min (H1-15; n = 8) or 0.4 mm (H2-5; n = 8) or 0.2 mm sevoflurane (L2-5; n = 8) twice for 5 min, with a 5-min washout period interspersed. Sevoflurane was then washed out for 20 min before 30 min of global no-flow ischemia and 120 min of reperfusion. Control hearts (n = 8) were not subjected to APC. Left ventricular pressure was measured isovolumetrically. Ventricular infarct size was determined by tetrazolium staining and cumulative planimetry. Values are expressed as mean +/- SD.

Results: The authors found a better functional return and a lesser percentage of infarction on reperfusion in H2-5 (28 +/- 9%) than in H1-15 (36 +/- 8%; P < 0.05), L2-5 (43 +/- 6%; P < 0.05), or control hearts (52 +/- 7%; P < 0.05).  相似文献   

64.
65.
66.
The Effect of Cuts in Medicare Reimbursement on Hospital Mortality   总被引:1,自引:0,他引:1  
Objective. To determine if patients treated at hospitals under different levels of financial strain from the Balanced Budget Act (BBA) of 1997 had differential changes in 30-day mortality, and whether vulnerable patient populations such as the uninsured were disproportionately affected.
Data Source. Hospital discharge data from all general acute care hospitals in Pennsylvania from 1997 to 2001.
Study Design. A multivariate regression analysis was performed retrospectively on 30-day mortality rates, using hospital discharge data, hospital financial data, and death certificate information from Pennsylvania.
Data Collection. We used 370,017 hospital episodes with one of four conditions identified by the Agency for Healthcare Research and Quality as inpatient quality indicators were extracted.
Principal Findings. The average magnitude of Medicare payment reduction on overall net revenues was estimated at 1.8 percent for hospitals with low BBA impact and 3.6 percent for hospitals with a high impact in 1998, worsening to 2 and 4.8 percent, respectively, by 2001. Operating margins decreased significantly over the time period for all hospitals ( p <.05). While unadjusted mortality rates demonstrated a disproportionate rise in mortality for patients from high impact hospitals from 1997 to 2000, adjusted analyses show no consistent, significant difference in the rate of change in mortality between high-impact and low-impact hospitals ( p =.04–.94). Similarly, uninsured patients did not experience greater increases in mortality in high-impact hospitals relative to low-impact hospitals.
Conclusions. An analysis of hospitalizations in the Commonwealth of Pennsylvania did not find an adverse impact of increased financial strain from the BBA on patient mortality either among all patients or among the uninsured.  相似文献   
67.
The present study examined the false negative error rate associated with the optional use of the Retention trial the Test of Memory Malingering (TOMM). TOMM scores from 150 traumatic brain injury and 150 chronic pain patients were examined. Results indicated that early termination of the TOMM resulted in 3% of patients going undetected by the TOMM. The practical cost of this error was minimized by the inclusion of at least one other SVT. Clinical implications are discussed.  相似文献   
68.
69.
The study reports on a questionnaire study of final-year medical students' self-reported attitudes to dealing with dying patients. All respondents had some direct clinical experience with dying patients, and reported that such encounters were largely unproblematic. Alleviating patient anxiety and counseling relatives were seen as important aspects of the doctor's role, along with diagnosis, and management of symptoms. “High fear” respondents were more likely to report difficulty in discussing the prognosis with the dying and to experience minor psychological problems.  相似文献   
70.
The case of a 19 year old man struck by lightning is described. He sustained quadriplegia for several months and fully recovered. It is suggested that his weakness was due to extensive peripheral nerve damage. In addition, he displayed many well recognised medical complications of lightning injury including acute renal failure, rhabdomyolysis, respiratory distress syndrome, autonomic dysfunction, perforated ear drum, uveitis and cataract. The literature relating to the neurology of lightning strike is briefly reviewed.  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