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   37222篇
  免费   2039篇
  国内免费   211篇
耳鼻咽喉   354篇
儿科学   561篇
妇产科学   405篇
基础医学   4970篇
口腔科学   1048篇
临床医学   2396篇
内科学   9166篇
皮肤病学   906篇
神经病学   2553篇
特种医学   1469篇
外科学   6547篇
综合类   176篇
一般理论   1篇
预防医学   1156篇
眼科学   725篇
药学   2701篇
中国医学   47篇
肿瘤学   4291篇
  2023年   183篇
  2022年   429篇
  2021年   735篇
  2020年   430篇
  2019年   542篇
  2018年   721篇
  2017年   623篇
  2016年   693篇
  2015年   734篇
  2014年   940篇
  2013年   1176篇
  2012年   1789篇
  2011年   1890篇
  2010年   1112篇
  2009年   982篇
  2008年   1640篇
  2007年   1582篇
  2006年   1644篇
  2005年   1724篇
  2004年   1606篇
  2003年   1625篇
  2002年   1535篇
  2001年   1339篇
  2000年   1360篇
  1999年   1253篇
  1998年   472篇
  1997年   401篇
  1996年   355篇
  1995年   326篇
  1994年   272篇
  1993年   272篇
  1992年   848篇
  1991年   750篇
  1990年   750篇
  1989年   708篇
  1988年   719篇
  1987年   629篇
  1986年   620篇
  1985年   605篇
  1984年   398篇
  1983年   332篇
  1982年   159篇
  1979年   322篇
  1978年   206篇
  1977年   153篇
  1975年   152篇
  1974年   215篇
  1973年   152篇
  1972年   165篇
  1971年   148篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We implanted normal peripheral blood lymphocytes (PBL) from healthy donors and splenic tissues from patients with gastric cancers into the severe combined immunodeficient (SCID) mouse, demonstrating that SCID mouse with splenic tissue can produce a high level of human immunoglobulin G (IgG). The normal PBLs at 10(7) and 10(8)/mouse were implanted intraperitoneally, and three splenic tissues with a size of 3 x 3 x 3 mm from gastric cancer patients were inoculated subcutaneously into the bilateral backs of the mice. At 2, 4, 6 and 8 weeks after inoculation, mice were killed, and the human IgG was assessed by an ELISA method. SCID mice with splenic tissue revealed high human IgG levels from 2 weeks after inoculation and approximately 2 mg of IgG per ml was observed at 8 weeks post-implantation, while the IgG levels in mice treated with PBLs were limited. Since the half life of the extrinsic human IgG was 10.2 days, the high level of human IgG in the SCID mice was supposed to be produced by human plasma cells in the splenic tissue from gastric cancer patients. This model was thought to be adequate for evaluating human immunological functions in vivo.  相似文献   
62.
In order to elucidate the roles of hippocampal N-methyl-D-aspartate-type excitatory amino acid receptors in working and reference memory in rats, the effects of intrahippocampal injections of selective and competitive N-methyl-D-aspartate receptor antagonists such as CGS 19755 (cis-4-phosphonomethyl-2-piperidine carboxylic acid), 3-[(+-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid and 2-amino-5-phosphonovaleric acid on this behavior were examined with a three-panel runway task. The results were compared with the effect of the muscarinic receptor antagonist scopolamine. In the working memory task, CGS 19755 and 3-[(+-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid at 10 and 32 ng/side, injected bilaterally into the dorsal hippocampus before testing, produced a significant increase in the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points). This also occurred after the rats were given systemic injection of these drugs at 3.2 and 10 mg/kg. In the reference memory task, neither CGS 19755 nor 3-[(+-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid affected the number of errors, whether given at doses up to 32 ng/side intrahippocampally or up to 10 mg/kg systemically. Working memory errors also increased significantly after intrahippocampal injections of d-2-amino-5-phosphonovaleric acid at 100 and 320 ng/side, but were not affected by I-2-amino-5-phosphonovaleric acid at doses up to 1 microgram/side. On the other hand, intrahippocampal scopolamine at 1.0 and 3.2 micrograms/side increased significantly working memory errors, without affecting reference memory errors.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
63.
We report the case of a 52-year-old female with middle-ear paraganglioma masquerading as a traumatic facial palsy, and describe the diagnostic steps and surgical treatment by the tympanomastoid approach.  相似文献   
64.
To apply Nd:YAG laser irradiation through a new sapphire tip contact laser method to catheter ablation in treatment of tachy-arrhythmias, effects of laser irradiation on ventricular myocardium were investigated in 10 mongrel dogs. Nd:YAG lase (1064nm) discharges were delivered to different sites on the endomyocardium at power of 5, 10, 15, 20 or 25w with duration of 3, 5, or 10 seconds (sec.) respectively in closed beating hearts. Histopathologically, the lesion irradiated was clearly demarcated from the normal myocardium by the construction band necrosis zone. The depth of injured myocardium was less than 2mm with 3 sec. irradiations, with 5 sec. from 1 mm to 4 mm in proportion to power increase, with 10 sec. from 3mm to 8 mm in proportion to the power from 5w to 15w and could not be measured in cases of more than 20w irradiations. Although with every irradiation duration, the depth of injury increased in proportion to the power increase. With the same total energy, a longer time of irradiation produced deeper injury than a shorter time. This method makes it easier to keep the laser positioned to target than bare laser, and is suitable for use in catheter ablation.  相似文献   
65.
The effects of potassium in reperfusion solution (RS) and the influence of sodium on this effect were studied. Experimental time course was as followed: 20 min working perfusion, 3 min cardioplegic infusion with St. Thomas Cardioplegic Solution followed by global ischemia for 33 or 35 min at 37.5 degrees C, 15 min early Langendorff reperfusion with several different potassium concentration modified with Krebs Henseleit Bicarbonate Buffer (KHBB) containing 145 mM and 110 mM sodium and 5 min late reperfusion with KHBB, followed by 20 min working perfusion. Potassium in RS possessed bell shaped dose response nature with optimal concentration of 10 mM in the condition of 145 mM sodium but 6 m in the condition of 110 mM in terms of percent recovery of aortic flow. Although higher potassium reperfusion produced less Creatine Kinase leakage.  相似文献   
66.
The vascular type of Ehlers-Danlos syndrome is a genetic disorder of connective tissue and is frequently associated with catastrophic arterial complications. Its surgical treatment is extremely difficult because of the fragility of vessels. This article describes three patients with vascular type of Ehlers-Danlos syndrome who developed mesenteric hemorrhage due to spontaneous arterial rupture. The clinical and molecular characteristics of the disease are briefly reviewed.  相似文献   
67.
Abstract:  Carbohydrate (Carb) counting is a meal planning approach for patients with diabetes mellitus that focuses on carbohydrate as the primary nutrient affecting postprandial glycemic response. The concept of carb counting is not new. In the early 1990`s the Diabetes Control and Complications Trial (DCCT) used carb counting as one of its education tools. More recently, short acting insulin analogues and insulin pumps have made the role of carb counting important and popular. Carb counting can be used in conjunction with a meal plan to set carbohydrate targets at each meal and snack. It is also used, perhaps more commonly, to estimate carbohydrate intake and adjust insulin around mixed meals and snacks using insulin to carbohydrate ratio. This effectively addresses the variable eating habits of most children and adolescents. The method may be adapted for patients who use a conventional insulin regimen and may meet the needs of patients who use multiple daily injections (MDI) or an insulin pump. Carb counting can make food planning flexible and enjoyable for patients, and the meal planning approach is very important for the physical growth and psychological development of children with diabetes. This paper describes the importance of carb counting for childhood diabetes as well as some of the special aspects associated with it.  相似文献   
68.
69.
The three human isozymes of alkaline phosphatases were quantitatively determined in normal testis and seminoma tissues. The highly selective assays were based on isozyme specific monoclonal antibodies. In the normal testis approximately 90% of the catalytic activity originates from the tissue unspecific alkaline phosphatase, and the remaining activity was due to trace expression of both intestinal (approximately 5%) and placental alkaline phosphatase (PLAP) or PLAP-like isozyme (approximately 5%). In homogenates of seminoma tissues, highly increased levels of all three isozymes were identified. Both the tissue unspecific alkaline phosphatase and PLAP-like enzymes displayed relative increases of 10- to 100-fold and intestinal alkaline phosphatase 2- to 10-fold compared with normal testis. This finding indicates that the entire genome coding for alkaline phosphatases may be activated in seminomas. The PLAP-like enzyme from seminoma cells comprises a heterogenous population of molecules demonstrating partial heat sensitivity and microheterogeneity upon starch gel electrophoresis in contrast to the pregnancy related PLAP. These findings have implications for the different PLAP assays used in the clinical monitoring of seminoma patients.  相似文献   
70.
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