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   22492篇
  免费   1039篇
  国内免费   101篇
耳鼻咽喉   187篇
儿科学   310篇
妇产科学   391篇
基础医学   2922篇
口腔科学   553篇
临床医学   1425篇
内科学   5920篇
皮肤病学   333篇
神经病学   1863篇
特种医学   821篇
外科学   3483篇
综合类   91篇
一般理论   2篇
预防医学   579篇
眼科学   551篇
药学   1850篇
中国医学   78篇
肿瘤学   2273篇
  2022年   187篇
  2021年   316篇
  2020年   243篇
  2019年   266篇
  2018年   318篇
  2017年   265篇
  2016年   353篇
  2015年   352篇
  2014年   488篇
  2013年   609篇
  2012年   972篇
  2011年   1055篇
  2010年   586篇
  2009年   488篇
  2008年   919篇
  2007年   979篇
  2006年   921篇
  2005年   947篇
  2004年   1035篇
  2003年   936篇
  2002年   974篇
  2001年   905篇
  2000年   962篇
  1999年   901篇
  1998年   294篇
  1997年   220篇
  1996年   199篇
  1995年   177篇
  1994年   174篇
  1993年   163篇
  1992年   630篇
  1991年   522篇
  1990年   532篇
  1989年   545篇
  1988年   484篇
  1987年   422篇
  1986年   388篇
  1985年   408篇
  1984年   288篇
  1983年   224篇
  1982年   104篇
  1979年   206篇
  1978年   135篇
  1977年   125篇
  1974年   99篇
  1972年   107篇
  1971年   102篇
  1970年   98篇
  1968年   115篇
  1967年   102篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
In order to complete operations without blood transfusion we have chosen means of preoperative autologous blood saving and intraoperative autotransfusion, but we have not always achieved our purpose. We examined 29 patients (13 patients without blood transfusion and 16 with blood transfusion) to analyze the determinant factors as to whether open heart surgery without blood transfusion may be indicated or not, according to the quantification theory (type II) and to examine the possibility to apply the maximum surgical blood order schedule (MSBOS) for the open heart surgery by the quantification theory (type I). The analysis of determinant factors revealed hematocrit (Ht) value before saving of blood (more than 40%) as the best contributor of possibility of non-blood transfusion surgery, followed by the amount of blood loss during operation (less than 600 ml), the amount of saving blood (more than 800 ml), body weight (less than 70 kg), calculated Ht value on the beginning of cardiopulmonary bypass (CPB) (more than 24%), CPB time (less than 120 minutes) and the amount of postoperative blood loss (less than 600 ml). The prospective using blood volume at the operation was precisely calculated by the values of 4 preoperative factors, that is, the amount of saving blood, calculated Ht value on the beginning of CPB, CPB time and body weight. Therefore it is important to increase the amount of preoperative saving blood and decrease the amount of surgical bleeding in order to perform operations without blood transfusion, and is possible to apply the MSBOS for the open heart surgery.  相似文献   
53.
Expression of mRNAs encoding the erythroid-specific delta-aminolevulinate synthase (ALAS-E) and the nonspecific delta-aminolevulinate synthase (ALAS-N) were examined in murine Friend virus-transformed erythroleukemia (MEL) cells using nonradioactive in situ hybridization. Following dimethyl sulfoxide (DMSO) treatment, ALAS-E mRNA increased markedly, while ALAS-N mRNA did not increase in wild-type MEL cells. In contrast, in a DMSO-resistant clone of MEL cells, ALAS-E was not detectable before and after DMSO treatment. These findings suggest that ALAS-E and ALAS-N mRNAs are under separate controls and that the expression of ALAS-E mRNA is a critical event in erythroid differentiation.  相似文献   
54.
An ulnar recurrent adipofascial flap was raised and turned over to reconstruct massive defects around the elbow and forearm after wide resection of malignant tumours. Compared to the fasciocutaneous flap, the ulnar recurrent adipofascial flap has the following advantages: (1) a larger flap can be harvested without the problem of primary closure of the donor site, (2) the contour and scar of the donor site is reasonably acceptable since no tension is presented, (3) the flap can be turned over to cover a wider area, and (4) debulking of the flap can be performed during the operation if needed. The rotation arc of the ulnar recurrent adipofascial flap reaches a wide region, including the distal one-half of the upper arm, the elbow, and the proximal two-thirds of the forearm. Sensory deficit in the forearm was avoided in our patients because meticulous separation and preservation of the medial cutaneous nerve of the forearm was achieved without jeopardising the blood supply to the flap. The ulnar recurrent adipofascial flap is an easy and reliable option for one-stage reconstruction of massive defects around the elbow.  相似文献   
55.
56.
Analysis of DNA ploidy patterns was performed on 76 diffusely infiltrating carcinomas of the stomach and the results correlated with histologic findings and outcome. Twenty six cases were diploid (34%) and 50 cases were aneuploid. There was no correlation between DNA ploidy and histologic type, depth of invasion, lymphatic invasion, evidence of peritoneal dissemination or curability. In aneuploid tumors, incidence of vascular invasion was significantly higher than that in diploid tumors (p less than 0.05). In addition, the patients with aneuploid tumors had a poor prognosis than with diploid tumors. These results indicate that DNA ploidy patterns may possibly be a useful prognostic marker for diffusely infiltrating carcinomas of the stomach.  相似文献   
57.
Helicobacter pylori (HP) has been shown to possibly be a pathogen of gastric carcinoma. HP has urease activity and produces ammonia in the stomach. In this study, the role of ammonia on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in rats. After 24 weeks pretreatment with MNNG (83 mg/l), 0.01% ammonia or tap water as a drinking water was administered for 24 weeks. The ammonia-treated rats showed a significantly higher incidence of gastric cancer (percent of animals with tumors and number of tumors per rat). Ammonia would thus appear to have an important role in HP-related human gastric carcinogenesis.  相似文献   
58.
Limited vertical skin incision for median sternotomy.   总被引:4,自引:0,他引:4  
The cosmetic deformity of the vertical skin incision for median sternotomy was decreased by using a mechanical traction system to increase exposure at the superior margin of a shorter wound. The limited vertical skin incision did not impede technical surgical maneuvers and produced a scar that was more acceptable than submammary incision or right anterior thoracotomy. The limited skin incision is especially useful in young women with congenital heart disease.  相似文献   
59.
60.
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