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   34529篇
  免费   3479篇
  国内免费   2563篇
耳鼻咽喉   211篇
儿科学   476篇
妇产科学   392篇
基础医学   4215篇
口腔科学   621篇
临床医学   4474篇
内科学   5376篇
皮肤病学   320篇
神经病学   1553篇
特种医学   1131篇
外国民族医学   29篇
外科学   3732篇
综合类   5991篇
现状与发展   9篇
一般理论   3篇
预防医学   2389篇
眼科学   932篇
药学   3790篇
  32篇
中国医学   2003篇
肿瘤学   2892篇
  2024年   166篇
  2023年   697篇
  2022年   1661篇
  2021年   2098篇
  2020年   1451篇
  2019年   1240篇
  2018年   1219篇
  2017年   1137篇
  2016年   1044篇
  2015年   1554篇
  2014年   1944篇
  2013年   1747篇
  2012年   2494篇
  2011年   2797篇
  2010年   1716篇
  2009年   1365篇
  2008年   1720篇
  2007年   1849篇
  2006年   1685篇
  2005年   1616篇
  2004年   1144篇
  2003年   1103篇
  2002年   961篇
  2001年   782篇
  2000年   760篇
  1999年   765篇
  1998年   448篇
  1997年   468篇
  1996年   357篇
  1995年   343篇
  1994年   333篇
  1993年   188篇
  1992年   231篇
  1991年   229篇
  1990年   243篇
  1989年   185篇
  1988年   153篇
  1987年   120篇
  1986年   123篇
  1985年   93篇
  1984年   70篇
  1983年   39篇
  1982年   27篇
  1981年   22篇
  1979年   20篇
  1977年   16篇
  1975年   14篇
  1974年   19篇
  1972年   13篇
  1969年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Morphine can modulate the processes underlying memory in vertebrates. However, studies have shown various modulations by morphine: positive, negative and even neutral. The honeybee is a potential platform for evaluating the effects of drugs, especially addictive drugs, on the nervous system. However, the involvement of morphine in learning and memory in insects or other invertebrates is poorly understood. The current work evaluated whether morphine affects memory acquisition, consolidation and retrieval in honeybees, using the proboscis extension response (PER) paradigm. We demonstrated that morphine treatment (5 μg/bee) before training decreased the percentage of correct PERs and the response latency related to aversive rather than rewarding odors when tested after 1 or 24 h. Morphine treatment after training also caused a decrease in this latency when tested after 24 h. Meanwhile, morphine treatment reduced the ambulation distance when tested after 30 min. Our findings suggest that morphine impairs the acquisition of short- and long-term associative memory and slightly disrupts the consolidation of long-term memory in honeybees. These negative effects cannot be explained by reduced locomotion but by impaired memory associated with aversion.  相似文献   
994.
红细胞分布宽度(red cell distribution width,RDW)是通过定量的方法反映循环中红细胞大小变异性的指标.近期较多研究发现RDW的升高能够作为预测人群心血管疾病预后不良的指标,即使RDW值在正常参考值范围内,处于高值的人群存在更高的心血管疾病死亡风险.本文综述了RDW与高血压发病、血压水平、血压形态及靶器官损害之间的关系,并探讨了RDW升高提示高血压预后不良的机制.由于RDW简单易得,可以作为高血压患者预后风险评估有潜力的指标.  相似文献   
995.
Killer cell immunoglobulin‐like receptors (KIRs) show extensive variation among different populations. In this study, 404 unrelated individuals in Han population in Yunnan Province, China, were genotyped for the presence or the absence of 16 KIR genes using the multiplex PCR‐SSP method. Our data showed that the inhibitory gene frequency of genes KIR2DL1, KIR2DL3, KIR3DL1, KIR2DL5 and KIR2DL2 was 0.930, 0.889, 0.789, 0.206 and 0.095, respectively, and the activating gene frequency of KIR2DS4, KIR3DS1, KIR2DS1, KIR2DS5, KIR2DS2 and KIR2DS3 was 0.795, 0.218, 0.196, 0.165, 0.095 and 0.087, respectively. In all, 44 distinct KIR genotypes were identified; genotype 1 was predominant with a frequency of 0.478, followed by genotypes 2 and 8 with a frequency of 0.121 and 0.077, respectively. Haplotype A outnumbered haplotype B by 2.39:1. In addition, phylogenetic tree and multidimensional scaling analysis (MDS) based on KIR genes in populations including Asian, African and Caucasians have been performed. Neighbour‐joining tree analysis and the MDS plot showed that Han populations were clustered together with Asian and were separate from other populations. The Han populations in China were separated into northern and southern groups; the Yunnan Han population investigated in this study was clustered in the southern group. These results implied that the difference between northern and southern Han populations might reflect responses to a variety of locally acting epidemiological challenges.  相似文献   
996.

OBJECTIVES:

Patients with Type I neurofibromatosis scoliosis with intra-canal rib head protrusion are extremely rare. Current knowledge regarding the diagnosis and treatment for this situation are insufficient. The purpose of this study is to share our experience in the diagnosis and surgical treatments for such unique deformities.

METHODS:

Six patients with Type I neurofibromatosis scoliosis with rib head dislocation into the spinal canal were diagnosed at our institution. Posterior instrumentation and spinal fusion without intra-canal rib head resection via a posterior-only approach was performed for deformity correction and rib head extraction. The efficacy and outcomes of the surgery were evaluated by measurements before, immediately and 24 months after the surgery using the following parameters: coronal spinal Cobb angle, apex rotation and kyphosis of the spine and the intra-canal rib head position. Post-operative complications, surgery time and blood loss were also evaluated.

RESULTS:

Patients were followed up for at least 24 months post-operatively. The three dimensional spinal deformity was significantly improved and the intra-canal rib head was significantly extracted from the canal immediately after the surgery. At follow-up 24 months after surgery, solid fusions were achieved along the fusion segments, and the deformity corrections and rib head positions were well maintained. There were no surgery-related complications any time after the surgery.

CONCLUSIONS:

Systematic examinations are needed to identify patients with Type I neurofibromatosis scoliosis with rib head dislocation into the canal who can be treated by posterior-only spinal fusion without rib head resection.  相似文献   
997.
998.
A 70-year-old woman visited a local hospital complaining of a nodulein the right breast, present since 1 month. She was referred to our hospital for further evaluation. Following mammotome (MMT) biopsy, the nodule was diagnosed as myxoid/round cell liposarcoma. She underwent total mastectomy of the right breast. Histological analysis indicated that the tumor was almost entirely composed of proliferating small round mesenchymal cells in amyxoid matrix background with capillary-like vessels with partial necrosis (<10%). Immunohistochemically, p53 positive cells were seen focally (<1%) only, and the Ki-67 labeling index was approximately 20%. Sincethe surgical margin was histologically positive despite pathologic findings of high-grade malignancy, adjuvant treatment involving local radiation therapy (60Gy) was administered. The patient was free from any symptoms of local recurrence and metastases 1 year and 8 months after surgery.  相似文献   
999.
目的:使用锥形束CT(CBCT)对唇腭裂患者上颌窦状况进行分析。方法:对四川大学华西口腔医院2012年1~6月收治的用CBCT确诊为唇腭裂的患者进行研究,观察其上颌窦情况并分析。结果:唇腭裂患者上颌窦病变发生率为78.1%。根据病变不同的影像学表现可分为黏膜增厚型(51.3%),粘液囊肿型(19.3%)及积液型(22.7%)。上颌窦黏膜增厚的平均厚度为2.40 mm;粘液囊肿的平均最大径为7.60 mm。上颌窦病变可发生于单侧上颌窦,也可双侧同时发生。结论:CBCT作为一种实用有效的影像学检查,在对患者唇腭裂状况评价的同时,也可以准确地判断唇腭裂患者上颌窦情况。  相似文献   
1000.
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