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   2292篇
  免费   290篇
  国内免费   19篇
耳鼻咽喉   15篇
儿科学   84篇
妇产科学   34篇
基础医学   322篇
口腔科学   19篇
临床医学   254篇
内科学   507篇
皮肤病学   52篇
神经病学   115篇
特种医学   221篇
外科学   244篇
综合类   85篇
一般理论   2篇
预防医学   267篇
眼科学   17篇
药学   216篇
  2篇
中国医学   2篇
肿瘤学   143篇
  2021年   39篇
  2020年   25篇
  2019年   29篇
  2018年   34篇
  2017年   20篇
  2016年   20篇
  2015年   22篇
  2014年   43篇
  2013年   61篇
  2012年   86篇
  2011年   93篇
  2010年   43篇
  2009年   39篇
  2008年   97篇
  2007年   106篇
  2006年   100篇
  2005年   88篇
  2004年   92篇
  2003年   74篇
  2002年   77篇
  2001年   57篇
  2000年   73篇
  1999年   69篇
  1998年   49篇
  1997年   50篇
  1996年   62篇
  1995年   39篇
  1994年   43篇
  1993年   44篇
  1992年   47篇
  1991年   42篇
  1990年   44篇
  1989年   84篇
  1988年   55篇
  1987年   62篇
  1986年   52篇
  1985年   57篇
  1984年   36篇
  1983年   36篇
  1982年   24篇
  1980年   23篇
  1979年   28篇
  1978年   21篇
  1977年   24篇
  1976年   19篇
  1974年   21篇
  1973年   21篇
  1972年   35篇
  1969年   22篇
  1968年   22篇
排序方式: 共有2601条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Recipients of hearts from donors with spontaneous intracerebral hemorrhage (ICH) are at increased risk of allograft vasculopathy compared with trauma donors. We have recently shown that the vitronectin receptor (integrin alpha(V)beta3) is upregulated in transplant vasculopathy. We hypothesized that donor ICH is associated with systemic activation of alpha(V)beta3 in the donor before transplantation. METHODS: We evaluated mRNA expressions of alpha(V)beta3 (TaqMan PCR) in endomyocardial biopsy samples at 1-week post-transplant in 20 recipients from ICH donors and 20 recipients from trauma donors. To investigate whether systemic activation of alpha(V)beta3 was present in the donor before transplantation, alpha(V)beta3 expression was also evaluated in the corresponding donor spleen lymphocytes. All patients underwent serial coronary intravascular ultrasound to evaluate for coronary vasculopathy. The baseline characteristics were similar except for increased donor age in the ICH Group. RESULTS: The ICH Group showed significant increased mRNA expression of alpha(V)beta3 in the heart biopsy samples (3.8-fold, p = 0.012) and in the corresponding donor spleen lymphocytes (3.5-fold, p = 0.014) compared with the Trauma Group. At 1 year, the ICH Group also showed increased progression of coronary vasculopathy. Multivariate regression analysis found that donor lymphocytic alpha(V)beta3 mRNA expression was independently associated with increased risk of vasculopathy (odds ratio, 1.9; 95% CI, 1.21-3.98, p = 0.03). CONCLUSIONS: Our report demonstrates the presence of systemic activation of alpha(V)beta3 in donors with spontaneous intracerebral hemorrhage and its association with the subsequent development of allograft vasculopathy in the recipient.  相似文献   
2.
BACKGROUND: The epidemiology of superficial venous disease is relatively well defined in the U.K. Caucasian population. By contrast, there are currently no data available for Asians, who comprise 3.6% of the U.K., and 14.1% of this institution's catchment population. The aim of this study was to compare surgery for superficial venous disease in Caucasians and Asians in this institution, in the context of our local population. METHODS: A prospectively gathered database of all 2011 superficial venous operations performed between January 1997 and April 2002 was retrospectively analysed with regard to ethnicity. The ethnic, gender and age composition of our catchment area was determined from U.K. census data. The full institutional records of 100 Asian and 100 randomly selected age and sex-matched Caucasian patients were compared in a case control study. RESULTS: After adjusting for age and gender according to census data, Asians were 40% less likely to undergo superficial venous surgery (SVS). Considering the 2011 operated patients as a whole, Asians were significantly younger and more likely to be male. In the case control study, Asians were significantly less likely to be operated for recurrent disease and significantly more likely to be operated for advanced disease. CONCLUSIONS: Although Asians are significantly less likely to undergo SVS; those that do are more likely to be young, male and operated for skin changes and ulcers. This strongly suggests that the under-representation of Asians is due to cultural, genetic or environmental factors and unmet health care need, rather than a lower prevalence of clinically significant venous disease in the Asian population.  相似文献   
3.
The pelvic congestion syndrome   总被引:4,自引:0,他引:4  
Perivulval varices appear during pregnancy and usually disappear after delivery but become more prominent with subsequent pregnancies. They may extend over the buttock and may be associated with recurrent leg varices. Some patients have extensive varices in the broad ligaments and present with the pelvic congestion syndrome. These patients have been shown to have grossly dilated ovarian veins. Elimination of this proximal incompetence relieves the symptoms.  相似文献   
4.
5.
SUMMARY Four specialised air mattresses had interface pressure measured under six body sites prone to pressure sores in 10 subjects, supine and sitting. The mattresses were the Clinirest (SSI) and FirstStep (KCI) continuous airflow mattress overlays, and Airwave (Pegasus) and Nimbus (Huntleigh) alternating pressure air mattresses. On the mattress overlays, average supine interface pressures were 2.33 kPa (scapula), 4.15 kPa (elbow), 1.94 kPa (sacrum) and 2.79 kPa (buttock), although they were higher at the occiput (7.97 kPa) and heel (11.7 kPa). The alternating pressure air mattresses had an average minimum interface pressure close to zero for three sites, rising to 4.28 kPa under the heel. Average maximum interface pressures were 8.61 kPa (occiput), 5.21 kPa (scapula), 4.90 (elbow), 4.85 kPa (sacrum), 4.61 kPa (buttock) and 13.2 kPa (heel). No accepted scientific method exists for comparing the two types of mattress. Our data suggest a clinical benefit at the occiput and heel (supine) in using an alternating pressure air mattress and a benefit in using a continuous airflow mattress overlay at other sites.  相似文献   
6.
7.
Mercury sphygmomanometers have been commonly used in primary care to measure blood pressure but are associated with bias. Electronic blood pressure machines are being introduced in many practices and have anecdotally been associated with higher recorded blood pressure. This study examined recorded blood pressure in four practices before and after electronic blood pressure machine introduction. No consistent change in mean blood pressure was apparent following their introduction, but there was a large and significant fall in terminal digit preference suggesting improved precision of recording.  相似文献   
8.
Abstract: In order to consider whether admission to a special hostel was a desirable policy in view of the likelihood of subsequent transfer to a nursing home, this study compared the time spent by residents in a special hostel with the period in a nursing home after they were transferred out of the hostel. We also estimated the number of nursing home places necessary for residents who were transferred and studied the reasons for transfer. The setting was a special hostel in Perth, Western Australia, for 36 people with moderate or severe dementia. The periods spent in the hostel or a nursing home were calculated for all residents admitted between 1985 and 1990. Forty-two of the 84 residents admitted during the study period were transferred to nursing homes. About two thirds of the total time in the two institutions was spent in the hostel. The two principal reasons necessitating transfer to a nursing home were advancing dementia and the addition of a physical impairment. Because a major proportion of the care of selected people with dementia (who can no longer remain at home) can be undertaken in a special hostel, this facility should be included with standard hostel and nursing home in arrangements for institutional care. Between 20 and 25 nursing home places are necessary for residents transferred from a hostel of this size.  相似文献   
9.
10.
BACKGROUND: Hypertension is a potential risk factor for allograft coronary vasculopathy. We evaluated the efficacy of angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists, and their combined use, on the development of coronary vasculopathy in hypertensive heart transplant recipients. METHODS: Eighty-two heart transplant recipients underwent serial intravascular ultrasound (IVUS) analysis at baseline (within 1 month) and at 1 year after transplantation and were evaluated for the development of coronary vasculopathy. Patients were divided into 4 groups. Nineteen normotensive recipients received no treatment, control (Group A). Hypertensive patients were treated with either ACE inhibitors (Group B, n = 37), calcium antagonists (Group C, n = 16), or both (Group D, n = 10). RESULTS: We found a significant reduction in IVUS indices of coronary vasculopathy in heart transplant recipients who used a combination of an ACE inhibitor and a calcium antagonist compared with recipients who used either drug alone (p < 0.05). This synergistic efficacy was independent of the baseline indices evaluated in a multivariate regression analysis model and was noted despite comparable mean arterial pressure among the 3 hypertensive groups at 1 year, thus suggesting the presence of a synergistic anti-proliferative effect beyond the anti-hypertensive efficacy. CONCLUSIONS: The combined use of an ACE inhibitor and a calcium antagonist is more effective than the individual use of either drug alone on the development of coronary vasculopathy in cardiac transplant recipients. Large randomized clinical trials are warranted to evaluate such a synergistic efficacy.  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