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   38025篇
  免费   3324篇
  国内免费   1691篇
耳鼻咽喉   450篇
儿科学   649篇
妇产科学   639篇
基础医学   4491篇
口腔科学   643篇
临床医学   4298篇
内科学   6083篇
皮肤病学   789篇
神经病学   2380篇
特种医学   1212篇
外国民族医学   19篇
外科学   4564篇
综合类   5430篇
现状与发展   8篇
一般理论   20篇
预防医学   2456篇
眼科学   1343篇
药学   3278篇
  28篇
中国医学   1458篇
肿瘤学   2802篇
  2024年   91篇
  2023年   526篇
  2022年   1170篇
  2021年   1698篇
  2020年   1328篇
  2019年   1167篇
  2018年   1283篇
  2017年   1180篇
  2016年   1145篇
  2015年   1535篇
  2014年   1896篇
  2013年   1916篇
  2012年   2843篇
  2011年   2849篇
  2010年   1791篇
  2009年   1499篇
  2008年   2078篇
  2007年   2066篇
  2006年   1964篇
  2005年   1928篇
  2004年   1429篇
  2003年   1212篇
  2002年   1065篇
  2001年   898篇
  2000年   871篇
  1999年   822篇
  1998年   463篇
  1997年   391篇
  1996年   295篇
  1995年   309篇
  1994年   249篇
  1993年   172篇
  1992年   311篇
  1991年   295篇
  1990年   283篇
  1989年   260篇
  1988年   225篇
  1987年   205篇
  1986年   201篇
  1985年   151篇
  1984年   107篇
  1983年   72篇
  1982年   49篇
  1981年   53篇
  1979年   74篇
  1978年   51篇
  1977年   52篇
  1974年   66篇
  1973年   62篇
  1972年   63篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
41.
本文应用 ADP、肾上腺素及复合诱聚剂对30例慢性肾功能不全(尿毒症期)病人的血小板聚集功能进行了检测,其中5例在血液透析前后分别测定。结果表明尿毒症患者血小板聚集功能障碍,血液透析有助于改善血小板功能。通过相关性检验,发现尿毒症病人的血小板聚集率与血肌酐值呈负相关性,其意义尚需进一步探讨。  相似文献   
42.
43.
Two embryonal CNS tumors, atypical teratoid/rabdoid tumor (AT/RT) and primitive neuroectodermal tumor (PNET), may be confused with each other and misdiagnosed. Here we report an infant with a congenital supratentorial tumor, which was detected by fetal MRI at 37 weeks gestation. On routine histological examination, the tumor was composed mainly of small undifferentiated cells, among which many rhabdoid cells and occasional sickle‐shaped embracing cells were observed. No mesenchymal or epithelial areas were evident. Our impression was that the tumor was an atypical example of AT/RT. Immunohistochemically, almost all the tumor cells were strongly positive for vimentin. However, epithelial membrane antigen was notably negative, and most of the tumor cell nuclei were clearly positive for INI1. In addition, many tumor cells were positive for neurofilament protein. There were also occasional small areas containing many tumor cells positive for glial fibrillary acidic protein. Finally, a diagnosis of PNET, with a rhabdoid phenotype and expression of neuronal and glial markers, was made. In the present case, application of INI1 immunostaining was very helpful for distinguishing PNET from AT/RT.  相似文献   
44.
单甲氧聚乙二醇化学修饰药物酶的研究进展   总被引:4,自引:0,他引:4  
用单甲氧基聚乙二醉(1)化学修饰药物酶是生化药物研究开发的重要手段之一。本文综述了1化学修饰药物酶的一般方法及修饰后酶在生物和理化性质方面的变化,同时对1研究前景进行展望,并指出了尚待解决的问题。  相似文献   
45.
Motor imagery (MI), which refers to the process of mental representation of movements, has not been studied in patients with essential tremor (ET). We investigated the presence of impaired MI in ET patients compared with healthy controls. A group of drug-naive and nondemented ET patients and age-matched controls were studied using transcranial magnetic stimulation, while they were specifically instructed to try and imagine themselves performing two motor tasks. The various clinical and electrophysiological variables were evaluated and compared. Repeated measures ANOVA demonstrated a significant difference between ET patients and controls with respect to mean motor-evoked potential (MEP) amplitudes (F(1,38) = 31.92, P < 0.005) during MI. The process of MI effectively facilitated MEP amplitude in controls but not in ET patients, regardless of side of stimulation or motor tasks. We provide evidence to demonstrate impairment of MI in a group of ET patients compared with healthy controls. The basis for this novel finding is unclear, and further studies are warranted to determine whether it is related to cerebellar or motor cortical dysfunction.  相似文献   
46.
Previously we have shown that leukaemia inhibitory factor (LIF) potentiates the development of murine spinal cord neurons in vitro , suggesting that it, or related factors, may play an important regulatory role in neuronal development. We have further investigated this role and show here that the generation of neurons in cultures of embryonic day 10 spinal cord cells is inhibited by antibodies to the β subunit of the LIF receptor. Since there are more undifferentiated precursors in antibody-treated cultures than in control and LIF-treated cultures, it is concluded that the primary action of LIF, or related molecules, is to promote neuronal differentiation, not precursor survival. In addition, the failure of LIF to support neuronal survival in the period immediately following differentiation suggests that the increased numbers of neurons generated with LIF are not attributable to its neurotrophic action. By selecting neuronal precursors on the basis of their inability to express class I major histocompatibility complex molecules, it was shown that LIF acted directly upon these cells and not via an intermediary cell. LIF also appears to be involved in regulating the differentiation of astrocytes, since it increases the number of glial fibrillary protein (GFAP)-positive cells present in the cultures and since the spontaneous production of GFAP-positive cells is blocked by antibodies to the LIF β receptor. These findings suggest that LIF or related factors promote the differentiation of neural precursors in the spinal cord, but that they are not involved in preferentially promoting precursors down a specific differentiation pathway.  相似文献   
47.
Summary: This study was done to determine if impaired glucose tolerance in pregnancy was associated with increased maternal and neonatal morbidity and if so, whether the increased morbidity was due to the confounding factors of increased maternal age and maternal obesity. It was a retrospective analysis to compare 944 women with impaired glucose tolerance (IGT) in pregnancy with 10,065 women without abnormal glucose tolerance. The incidence of impaired glucose tolerance in pregnancy was 8.6% in this study. Even when maternal age and obesity were excluded, the IGT group had significantly higher risks of labour induction (relative risk, RR, 1.15); Caesarean section (RR: overall 1.43, elective 1.72, emergency 1.31); Caesarean section for dystocia/no progress (RR 1.60); macrosomia (RR 1.69,1.76,1.61 for birth-weight =97th, 95th, 90th percentiles respectively) and shoulder dystocia (RR 2.84) when compared to the nondiabetics (NDM). The risks of hypertensive disease (RR 1.22) and Caesarean section for fetal distress/thick meconium-stained liquor (RR 1.53) were also higher in the IGT group but these increases were not statistically significant when maternal age and obesity were excluded. There was no significant difference in the rates of low Apgar scores at 1 and 5 minutes between the 2 groups.  相似文献   
48.
Summary A total of 16 patients with recurrent epithelial ovarian cancer were treated with sulofenur (LY 186641), a novel oral sulfonylurea. All subjects had received previous chemotherapy. Anaemia occurred in all 16 patients, 14 of whom required a blood transfusion, and 2/16 patients received methylene blue for breathlessness due to methaemaglobinaemia. Treatment was discontinued in 2/16 cases due to rising liver enzyme values, which reverted to normal on cessation of the drug. There was no nausea or alopecia. Only two minor responses were seen. Plasma drug levels were insufficient to result in antitumour activity as extrapolated from animal data. Further studies that attempt to increase the bioavailability and improve the therapeutic index are warranted.  相似文献   
49.
The specialty which has benefited the most from the rapid development of reconstructive microsurgery over the last decade, has been plastic surgery. In particular, the authors refer to reconstructive microsurgery after malignant tumor resection. Resections which used to cause serious psychological problems or which required multiple reconstructive procedures, can now be performed as a single stage procedure with good oncological, functional and aesthetic results. This experience concerns the treatment of 14 primary or recurrent malignant tumors of the skin and soft tissues using microsurgical techniques. The free latissimus dorsi musculocutaneous flap was the flap most commonly used. The authors also used the groin flap, the scapular flap, the tensor fasciae latae flap, the dorsalis pedis flap and finally the jejunum combined with the second metatarsus to reconstruct the mandible and the floor of the mouth. Complications consisted of complete necrosis of a dorsalis pedis flap and two revisions were performed for venous thrombosis. With a minimum follow-up of 5 years, one patient has developed a local recurrence and another has developed regional lymph node metastases. The functional and aesthetic results were quite satisfactory. The authors believe that microsurgery is a very valuable technique to treat difficult reconstructive problems.  相似文献   
50.
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