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   185648篇
  免费   10541篇
  国内免费   1727篇
耳鼻咽喉   2437篇
儿科学   4443篇
妇产科学   5447篇
基础医学   27152篇
口腔科学   6198篇
临床医学   14383篇
内科学   38318篇
皮肤病学   4087篇
神经病学   13890篇
特种医学   5547篇
外国民族医学   3篇
外科学   25784篇
综合类   5496篇
一般理论   60篇
预防医学   14432篇
眼科学   4070篇
药学   14581篇
中国医学   1063篇
肿瘤学   10525篇
  2021年   2089篇
  2020年   1230篇
  2019年   2211篇
  2018年   3667篇
  2017年   2394篇
  2016年   2510篇
  2015年   3456篇
  2014年   3934篇
  2013年   5419篇
  2012年   9393篇
  2011年   9498篇
  2010年   4893篇
  2009年   3980篇
  2008年   8217篇
  2007年   8626篇
  2006年   8819篇
  2005年   8079篇
  2004年   7408篇
  2003年   6748篇
  2002年   6487篇
  2001年   8268篇
  2000年   8974篇
  1999年   6678篇
  1998年   2037篇
  1997年   1524篇
  1996年   1090篇
  1995年   1003篇
  1992年   3844篇
  1991年   3915篇
  1990年   3621篇
  1989年   3627篇
  1988年   3481篇
  1987年   3327篇
  1986年   3154篇
  1985年   3040篇
  1984年   2140篇
  1983年   1851篇
  1982年   1061篇
  1979年   1952篇
  1978年   1221篇
  1977年   1023篇
  1976年   952篇
  1975年   1214篇
  1974年   1391篇
  1973年   1440篇
  1972年   1362篇
  1971年   1260篇
  1970年   1149篇
  1969年   1134篇
  1968年   1027篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
In the current immunosuppressive therapy era, vessel thrombosis is the most common cause of early graft loss after renal transplantation. The prevalence of IgA anti–β2-glycoprotein I antibodies (IgA-aB2GPI-ab) in patients on dialysis is elevated (>30%), and these antibodies correlate with mortality and cardiovascular morbidity. To evaluate the effect of IgA-aB2GPI-ab in patients with transplants, we followed all patients transplanted from 2000 to 2002 in the Hospital 12 de Octubre prospectively for 10 years. Presence of IgA-aB2GPI-ab in pretransplant serum was examined retrospectively. Of 269 patients, 89 patients were positive for IgA-aB2GPI-ab (33%; group 1), and the remaining patients were negative (67%; group 2). Graft loss at 6 months post-transplant was significantly higher in group 1 (10 of 89 versus 3 of 180 patients in group 2; P=0.002). The most frequent cause of graft loss was thrombosis of the vessels, which was observed only in group 1 (8 of 10 versus 0 of 3 patients in group 2; P=0.04). Multivariate analysis showed that the presence of IgA-aB2GPI-ab was an independent risk factor for early graft loss (P=0.04) and delayed graft function (P=0.04). There were no significant differences regarding patient survival between the two groups. Graft survival was similar in both groups after 6 months. In conclusion, patients with pretransplant IgA-aB2GPI-ab have a high risk of early graft loss caused by thrombosis and a high risk of delayed graft function. Therefore, pretransplant IgA-aB2GPI-ab may have a detrimental effect on early clinical outcomes after renal transplantation.  相似文献   
4.
5.
6.
7.
Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24‐hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev‐erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP‐citrate lyase, malic enzyme, fatty acid synthase, and glucose‐6‐phosphate dehydrogenase) was abolished in pinealectomized animals.  相似文献   
8.
9.

Objective

To discover the experiences of end-of-life patients attended by the emergency services, through the discourse of the family caregivers who accompanied the family member in this care transit.

Method

A qualitative approach study, based on the paradigm of hermeneutical phenomenology. In total, 81 family caregivers participated. The techniques used were the in-depth interview and the discussion group, with a total of 5 discussion groups and 41 interviews. The period of data collection was carried out between January 2013 and June 2014.

Results

In the network of discourses obtained with respect to “Urgent Care”, all the codes were grouped in relation to a single argumentative line: deficiencies in urgent care. Among them, we found different dimensions that are established depending on the different times of care, or the different determinant aspects of these deficiencies: disorganization of the care received, lack of experience of the professionals in emergencies, application of general protocols in the emergency services, inadequate care in the treatment received, delays in emergency care.

Conclusions

In general, we highlight the dissatisfaction of the family members with respect to the care received from the emergency services. The needs of these types of situation are not covered from these services and are of low quality. Therefore, it is necessary to reorient the care protocols for these patients.  相似文献   
10.
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