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   1262320篇
  免费   96519篇
  国内免费   1579篇
耳鼻咽喉   16313篇
儿科学   41015篇
妇产科学   34948篇
基础医学   189405篇
口腔科学   34729篇
临床医学   117772篇
内科学   247913篇
皮肤病学   27279篇
神经病学   101863篇
特种医学   46771篇
外国民族医学   265篇
外科学   178584篇
综合类   25750篇
现状与发展   3篇
一般理论   568篇
预防医学   104654篇
眼科学   28044篇
药学   92561篇
  6篇
中国医学   2022篇
肿瘤学   69953篇
  2018年   13532篇
  2017年   10396篇
  2016年   11325篇
  2015年   13083篇
  2014年   18003篇
  2013年   27482篇
  2012年   37583篇
  2011年   39976篇
  2010年   23056篇
  2009年   22256篇
  2008年   37759篇
  2007年   40394篇
  2006年   39969篇
  2005年   39106篇
  2004年   37547篇
  2003年   35957篇
  2002年   34871篇
  2001年   56037篇
  2000年   57047篇
  1999年   48097篇
  1998年   13401篇
  1997年   12224篇
  1996年   12644篇
  1995年   11917篇
  1994年   11110篇
  1993年   10403篇
  1992年   38206篇
  1991年   37680篇
  1990年   36456篇
  1989年   35270篇
  1988年   32698篇
  1987年   32030篇
  1986年   30529篇
  1985年   28788篇
  1984年   21943篇
  1983年   19192篇
  1982年   11364篇
  1981年   10322篇
  1979年   20948篇
  1978年   15397篇
  1977年   12793篇
  1976年   11851篇
  1975年   12811篇
  1974年   15589篇
  1973年   15363篇
  1972年   14514篇
  1971年   13553篇
  1970年   12786篇
  1969年   12065篇
  1968年   11229篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
182.
PurposeRegional nodal irradiation (RNI) improved disease-free survival by 3% to 5% in 2 large randomized trials, but this small absolute advantage relies on accurate contouring and dose delivery. We audited our network to determine compliance on regional nodal coverage, contouring, and dosimetric parameters with respect to accepted guidelines.Methods and MaterialsIn our network, we have established a clinical pathway for patients with node-positive breast cancer that guides indications for RNI and dosimetric goals. We reviewed records of 183 patients with nodal macrometastases after upfront surgery or involved nodes of any size after neoadjuvant chemotherapy. Radiation treatment plans were examined to determine lymph node volumes treated, whether nodes were contoured, quality of nodal contours, and whether target coverage and normal organ dosimetric constraints were met when RNI was delivered.ResultsDespite the presence of macrometastases on sentinel lymph node biopsy, no lymph nodes were treated in 2.2% (4 of 183). Of 179 patients who received nodal irradiation, 18 received radiation to axillary levels 1 and 2 only, and 161 patients received RNI. Overall, regional nodes were not treated despite strong indications in 7.6% (14 of 183). Treated nodes were not contoured for 2.2% (4 of 179), and lymph node contours were unacceptable in 15.4% (27 of 175). Of patients receiving RNI, 14.9% (24 of 161) did not have adequate nodal target volume coverage, mean heart dose was >4 Gy for 3.1% (5 of 161), and lung V20 Gy was >35% for 8.7% (14 of 161).ConclusionsAdherence to indications for regional nodal treatment was high, but nodes were either not contoured or had unacceptable contour quality in 18% of plans, and coverage was inadequate in 15%. Because the small disease-free survival advantage seen in trials may be decreased with these deviations, routine clinical practice requires detailed peer review to fully translate results of clinical trials.  相似文献   
183.
Measurement of P-selectin on activated platelets as a means of measuring platelet function utilizing the technology described here has the advantage of not requiring immediate access to specialist equipment and expertise. Blood samples are activated, fixed, stored, and transported to a central laboratory for flow cytometric analysis. Here we have compared P-selectin with other more traditional approaches to measuring platelet function in blood and/or platelet-rich plasma (PRP) from patients with acute coronary syndromes on treatment for at least 1 month with either aspirin and clopidogrel or aspirin with prasugrel. The comparators were light transmission aggregometry (LTA), VerifyNow and Multiplate aggregometry (for determining the effects of aspirin) and LTA, VerifyNow and Multiplate together with the BioCytex VASP phosphorylation assay (for the P2Y12 antagonists). The P-selectin Aspirin Test revealed substantial inhibition of platelet function in all but three of 96 patients receiving aspirin with clopidogrel and in none of 51 patients receiving aspirin and prasugrel. The results were very similar to those obtained using LTA. There was only one patient with high residual platelet aggregation and low P-selectin expression. The same patients identified as “non-responders” to aspirin also presented with the highest residual platelet activity as measured using the VerifyNow system, although not quite as well separated from the other values. With the Multiplate test only one of these patients clearly stood out from the others. The results obtained using the P-selectin P2Y12 Test in 102 patients taking aspirin and clopidogrel were similar to the more traditional approaches in that a wide scatter of results was obtained. Generally, high values seen with the P-selectin P2Y12 Test were also high with the LTA, VerifyNow, Multiplate, and BioCytex VASP P2Y12 Tests. Similarly, low residual platelet function using the P2Y12 test was seen irrespective of the testing procedure used. However, there were differences in some patients. Prasugrel was always more effective than clopidogrel in inhibiting platelet function with none of 56 patients (P-selectin and VerifyNow), only 2 of 56 patients (Multiplate) and only 3 of 56 patients (Biocytex VASP) demonstrating high on-treatment residual platelet reactivity (HRPR) defined using previously published cut-off values. The exception was LTA where there were 11 of 56 patients with HRPR. It remains to be seen which experimental approach provides the most useful information regarding outcomes after adjusting therapies in treated patients.  相似文献   
184.
185.
186.
187.

Aims

Variations of the anatomy of donor hepatic arteries increase the number of arterial anastomoses during liver transplantation and, possibly, the incidence of hepatic artery thrombosis (HAT). In this study, we describe the arterial anatomic variations in liver grafts procured and transplanted by a single center in Greece, the techniques of arterial anastomosis, and their effect on the incidence of early HAT.

Materials and Methods

From January 2013 to December 2017, the arterial anatomy of 116 grafts procured for liver transplantation were recorded, as well as the technique of arterial anastomosis and the incidence of early hepatic artery thrombosis (HAT <30 days).

Results

A single hepatic artery was recorded in 72.41% of the procured grafts, an aberrant left hepatic artery (accessory or replaced) in 18 grafts (15.52%), and an aberrant right hepatic artery (accessory or replaced) in 17 grafts (14.66%), while other variations were observed in less than 1% of the procured livers. Of the 116 primary liver transplantations, 6 patients (5.17%) developed early HAT <30 days. Two of these patients (1.72%) had 1 anastomosis of the hepatic artery and 4 (3.45%) had 2 anastomoses due to anatomic variations.

Conclusions

Anatomic variations of the hepatic artery in liver grafts is a common finding and increase the incidence of early HAT but not to a degree to make these grafts unusable.  相似文献   
188.
Psoriasis is a common chronic inflammatory skin disease, affecting about 3% of the general population and approximately 2.5 million people in France, where this study took place. The genital area may be affected, however prevalence is poorly understood, meaning we do not know exactly how commonly this occurs. While it affects quality of life, genital psoriasis is under-recognized, probably due to the reluctance of patients to discuss genital involvement and sexual quality of life. The aims of this study, called the GENIPSO study, were to determine the prevalence of genital psoriasis, its clinical characteristics (its symptoms), whether it is associated with a particular type of psoriasis, and its impact on quality of life. The study included 776 adults seeing their doctor for psoriasis between November 2016 and March 2017. Among them, 336 (43.2%) had genital psoriasis. All these patients were aware that they had psoriasis on their genitals (genital lesions) but only 135 (40%) had already had a genital medical examination. Genital lesions were associated with (linked to) male gender, more severe psoriasis, first developing psoriasis when aged over 20 years, psoriasis of the skin folds, psoriasis on the scalp, nail and external auditory (ear) canal, but they were not associated with obesity or psoriatic arthritis. Itching was the main symptom. Genital psoriasis was associated with reduced quality of life and sexual health. The study found that genital psoriasis has a high prevalence in patients seeing their doctors about their psoriasis generally, it affects quality of life and should be better taken into account by dermatologists for the best possible care for patients.  相似文献   
189.
Several regulatory bodies have agreed that low-dose radiation used in medical imaging is a weak carcinogen that follows a linear, non-threshold model of cancer risk. While avoiding radiation is the best course of action to mitigate risk, computed tomography (CT) scans are often critical for diagnosis. In addition to the as low as reasonably achievable principle, a more concrete method of dose reduction for common CT imaging exams is the use of a diagnostic reference level (DRL). This paper examines Canada's national DRL values from the recent CT survey and compares it to published provincial DRLs as well as the DRLs in the United Kingdom and the United States of America for the 3 most common CT exams: head, chest, and abdomen/pelvis. Canada compares well on the international scale, but it should consider using more electronic dose monitoring solutions to create a culture of dose optimization.  相似文献   
190.
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