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   33362篇
  免费   2088篇
  国内免费   202篇
耳鼻咽喉   314篇
儿科学   561篇
妇产科学   448篇
基础医学   4645篇
口腔科学   887篇
临床医学   3436篇
内科学   7089篇
皮肤病学   661篇
神经病学   3704篇
特种医学   1953篇
外科学   5309篇
综合类   184篇
一般理论   7篇
预防医学   1407篇
眼科学   686篇
药学   1956篇
中国医学   68篇
肿瘤学   2337篇
  2024年   28篇
  2023年   268篇
  2022年   515篇
  2021年   886篇
  2020年   626篇
  2019年   811篇
  2018年   929篇
  2017年   798篇
  2016年   926篇
  2015年   1130篇
  2014年   1358篇
  2013年   1645篇
  2012年   2679篇
  2011年   2786篇
  2010年   1670篇
  2009年   1490篇
  2008年   2377篇
  2007年   2379篇
  2006年   2224篇
  2005年   2168篇
  2004年   1958篇
  2003年   1784篇
  2002年   1644篇
  2001年   283篇
  2000年   202篇
  1999年   263篇
  1998年   313篇
  1997年   235篇
  1996年   184篇
  1995年   159篇
  1994年   130篇
  1993年   122篇
  1992年   70篇
  1991年   57篇
  1990年   55篇
  1989年   37篇
  1988年   37篇
  1987年   29篇
  1986年   30篇
  1985年   25篇
  1984年   43篇
  1983年   26篇
  1982年   33篇
  1981年   27篇
  1980年   17篇
  1978年   12篇
  1977年   14篇
  1975年   9篇
  1974年   12篇
  1927年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Whole-brain echo-planar spectroscopic imaging (EPSI) often substantially lengthens MRI/MRSI (magnetic resonance spectroscopic imaging) protocols. To halve acquisition time, application of a blipped phase-encoding (PE) gradient during the EPSI readout (RO) was previously suggested by PE of the even RO echoes in k-space at an interstitial location along k(PE), separated from the odd RO echoes, effectively reducing the number of PEs by a factor of 2. However, the approach is very susceptible to phase inconsistencies between even and odd RO echoes in the presence of B(0) inhomogeneities and gradient imbalance, leading to ghosting in the PE direction. In this work, the blipped PE gradient is placed in between pairs of even/odd RO gradient lobes to avoid these problems. This approach is demonstrated in a phantom and in normal human brain in vivo at 4T. While the proposed method allows substantial reduction in metabolite ghosting, it may be limited by the presence of a relatively large spurious signal at the Nyquist frequency.  相似文献   
42.
43.
Introduction Delayed massive hemorrhage induced by pancreatic fistula after pancreaticoduodenectomy is a rare but life-threatening complication. The purpose of this study was to analyze the clinical course of patients with late hemorrhage, with or without sentinel bleeding, to better define treatment options in the future. Material and Methods From April 1998 to December 2006, 189 pancreaticoduodenectomies were performed. Eleven patients, including two patients referred from other hospitals, were treated with delayed massive hemorrhage occurring 5 days or more after pancreaticoduodenectomy. Sentinel bleeding was defined as minor blood loss via surgical drains or the gastrointestinal tract with an asymptomatic interval until development of hemorrhagic shock. The clinical data of patients with bleeding episodes were analyzed retrospectively. Results Eight of the 11 patients had sentinel bleeding, and seven of them had it at least 6 h before acute deterioration. Seven out of 11 patients died, five out of eight with sentinel bleeding. No differences could be detected between patients with or without sentinel bleeding before delayed massive hemorrhage. The only difference found was that non-surviving patients were significantly older than surviving patients. Delayed massive hemorrhage is a common cause of death after pancreaticoduodenostomy complicated by pancreatic fistula formation. The observation of sentinel bleeding should lead to emergency angiography and dependent from the result to emergency relaparotomy to increase the likelihood of survival.  相似文献   
44.
45.
46.
47.
OBJECTIVE: Due to limited resources, improvement of preservation solutions is still of great importance in cardiac transplant surgery. New additives with antioxidant properties were tested with respect to coronary function of isolated rat hearts. METHODS: Bretschneider HTK solution containing none or an antioxidant additive (deferoxamine, trolox or LK 616) was used for 8h cold cardioplegia. After reperfusion with Krebs-Henseleit buffer (KHB), we assessed vascular dilator capacity (bradykinin, adenosine triphosphate, reactive hyperemia), myocardial function (left ventricular developed pressure, heart rate, oxygen consumption) and release of biochemical markers (aspartate aminotransferase, creatine kinase, lactate dehydrogenase, troponin, adenosine). RESULTS: Bradykinin- and adenosine triphosphate-induced vasodilations were largely reduced in hearts stored 8h in traditional HTK as compared to unstored controls. Storage in HTK+LK 616 significantly improved bradykinin-induced vasodilation. Vasodilation toward ATP was best preserved in hearts stored in HTK+deferoxamine. Deferoxamine and trolox, both improved reactive hyperaemic response during reperfusion. Left ventricular pressure development was significantly reduced after 8h cardioplegia, but no difference existed between different cardioplegia groups. Release of biochemical markers of tissue injury was similar in all cardioplegia groups. After storage in HTK+LK 616 (100 microM), however, heart marker release was slightly augmented as compared to HTK. CONCLUSIONS: Despite similar myocardial function and marker release, coronary vascular function after cardioplegic storage may profit by addition of iron chelators (or antioxidants) to traditional HTK solution.  相似文献   
48.
49.
50.
4 patients with a mean age of 20 years and isolated congenital radial head dislocation (1 unilateral anterior, 1 unilateral posterior and 2 bilateral anterior dislocations) were all pain-free and had almost normal elbow function.  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