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   981943篇
  免费   65501篇
  国内免费   2530篇
耳鼻咽喉   13733篇
儿科学   31170篇
妇产科学   28379篇
基础医学   137721篇
口腔科学   26986篇
临床医学   79867篇
内科学   201344篇
皮肤病学   21395篇
神经病学   77847篇
特种医学   38091篇
外国民族医学   338篇
外科学   152037篇
综合类   19440篇
一般理论   272篇
预防医学   74238篇
眼科学   22002篇
药学   70248篇
中国医学   2069篇
肿瘤学   52797篇
  2019年   8034篇
  2018年   11953篇
  2017年   8867篇
  2016年   9288篇
  2015年   10582篇
  2014年   14332篇
  2013年   22391篇
  2012年   31191篇
  2011年   32906篇
  2010年   19378篇
  2009年   17808篇
  2008年   30703篇
  2007年   32591篇
  2006年   32596篇
  2005年   32163篇
  2004年   30568篇
  2003年   29396篇
  2002年   28808篇
  2001年   43629篇
  2000年   44935篇
  1999年   38168篇
  1998年   10338篇
  1997年   9355篇
  1996年   9314篇
  1995年   8624篇
  1994年   8233篇
  1993年   7707篇
  1992年   29173篇
  1991年   27851篇
  1990年   27260篇
  1989年   26115篇
  1988年   24257篇
  1987年   23875篇
  1986年   22903篇
  1985年   21789篇
  1984年   16273篇
  1983年   13851篇
  1982年   8254篇
  1979年   15088篇
  1978年   10512篇
  1977年   8867篇
  1976年   8418篇
  1975年   9243篇
  1974年   11147篇
  1973年   10621篇
  1972年   10020篇
  1971年   9242篇
  1970年   8963篇
  1969年   8382篇
  1968年   8031篇
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
91.
92.
The histologic distinction between peritoneal epithelioid mesotheliomas and serous carcinomas diffusely involving the peritoneum may be difficult, but it can be facilitated by the use of immunohistochemistry and electron microscopy. D2-40 and podoplanin are two recently recognized lymphatic endothelial markers that can be expressed in normal mesothelial cells and mesotheliomas. The purpose of this study is to compare the value of these new mesothelial markers with those that are commonly used for discriminating between mesotheliomas and serous carcinomas, and also to determine the current role of electron microscopy in distinguishing between these malignancies. A total of 40 peritoneal epithelioid mesotheliomas and 45 serous carcinomas of the ovary (15 primary, 30 metastatic to the peritoneum) were investigated for the expression of the following markers: D2-40, podoplanin, calretinin, keratin 5/6, thrombomodulin, MOC-31, Ber-EP4, B72.3 (TAG-72), BG-8 (Lewis(Y)), CA19-9, and leu-M1 (CD15). All 40 (100%) of the mesotheliomas reacted for calretinin, 93% for D2-40, 93% for podoplanin, 93% for keratin 5/6, 73% for thrombomodulin, 13% for Ber-EP4, 5% for MOC-31, 3% for BG-8, and none for B72.3, CA19-9, or leu-M1. All 45 (100%) serous carcinomas were positive for Ber-EP4, 98% for MOC-31, 73% for B72.3, 73% for BG-8, 67% for CA19-9, 58% for leu-M1, 31% for keratin 5/6, 31% for calretinin, 13% for D2-40, 13% for podoplanin, and 4% for thrombomodulin. After analyzing the results, it is concluded that Ber-EP4 and MOC-31 are the best negative mesothelioma markers for differentiating between epithelioid mesotheliomas and serous carcinomas. The best discriminators among the positive markers for mesotheliomas are D2-40, podoplanin, and calretinin. From a practical point of view, Ber-EP4 and MOC-31, in combination with calretinin, and/or D2-40 or podoplanin allow the differential diagnosis to be established between mesothelioma and serous carcinoma in nearly all instances. As a clear distinction could be made between these two malignancies in all of the cases in which electron microscopy was performed, this technique can be very useful in establishing the correct diagnosis when the immunohistochemical results are equivocal or further support of a diagnosis of either mesothelioma or serous carcinoma is needed.  相似文献   
93.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
94.
目的:描述胚胎种植前遗传诊断在1例携带Ⅰ型白细胞黏附缺陷病(LAD-1)携带者并完成健康妊娠夫妇中的应用。设计:病例报道。机构:大学医院生殖中心。患者:1例男女双方都是LAD-1携带者的夫妇,女方CD18基因的外显子4携带有G400A置换,男方的外显子5携带有C562T置换。干预:标准体外受精(IVF)后第3天行卵裂期活检和分裂球遗传分析以检测2处突变以及21号染色体标记物。主要观察指标:1个未罹患LAD-1婴儿的出生。结果:得到15个卵母细胞,其中10个受精。8个胚胎适宜胚胎活组织检查。  相似文献   
95.
Setting goals to maintain hope.   总被引:3,自引:0,他引:3  
  相似文献   
96.
97.
98.
Sniff nasal inspiratory pressure (SNIP) measurement is a volitional noninvasive assessment of inspiratory muscle strength. A maximum of 10 sniffs is generally used. The purpose of the present study was to investigate whether the maximum SNIP improved after the tenth sniff. In total, 20 healthy volunteers and 305 patients with various neuromuscular and lung diseases were encouraged to perform 40 and 20 sniffs, respectively. The best SNIP among the first 10 sniffs was lower than the best SNIP among the next 10 sniffs in the healthy volunteers and patients. The SNIP improvement after the twentieth sniff was marginal. In conclusion, a learning effect persists after the tenth sniff. The current authors suggest using 10 additional sniffs when the best result of the first 10 sniffs is slightly below normal, or when sniff nasal inspiratory pressure is used to monitor a progressive decline in inspiratory muscle strength.  相似文献   
99.
100.
Bone stock preservation is crucial when performing total hip replacement in young patients. The aim is to save good bone stock for a possible revision procedure. Furthermore, there is an increasing demand from young and active patients to receive a new joint which allows a normal or nearly normal life style. With this in mind, we began, in 1993, to develop a new femoral implant. The purpose of this ultra-short stem was a physiologic strain distribution on the proximal femur with a proximal load transfer from the implant to the femoral bone. Main features were an almost complete absence of the diaphyseal portion of the stem, a well defined lateral flare with load transfer on the lateral column of the femur, and a very high femoral neck cut. These innovations resulted in a conservative implant on both the bone stock and the soft tissues. This implant, in the first years, was recommended only for young and active patients. Over the last thirteen years, this project has undergone several modifications but the basic principles of the implant have remained the same. In the present review, we present the rationale, the surgical technique and the clinical and experimental results so far obtained with this implant.  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