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   183828篇
  免费   17463篇
  国内免费   11822篇
耳鼻咽喉   1648篇
儿科学   1922篇
妇产科学   2434篇
基础医学   21962篇
口腔科学   3332篇
临床医学   24038篇
内科学   26934篇
皮肤病学   2233篇
神经病学   9554篇
特种医学   6551篇
外国民族医学   102篇
外科学   18746篇
综合类   29979篇
现状与发展   39篇
一般理论   22篇
预防医学   12356篇
眼科学   4765篇
药学   19833篇
  193篇
中国医学   11040篇
肿瘤学   15430篇
  2024年   739篇
  2023年   3009篇
  2022年   7840篇
  2021年   9856篇
  2020年   7406篇
  2019年   6327篇
  2018年   6677篇
  2017年   6126篇
  2016年   5714篇
  2015年   8790篇
  2014年   10658篇
  2013年   9835篇
  2012年   14344篇
  2011年   15497篇
  2010年   9904篇
  2009年   7628篇
  2008年   10103篇
  2007年   9608篇
  2006年   9214篇
  2005年   8942篇
  2004年   5750篇
  2003年   5215篇
  2002年   4320篇
  2001年   3659篇
  2000年   3849篇
  1999年   3896篇
  1998年   2306篇
  1997年   2370篇
  1996年   1802篇
  1995年   1747篇
  1994年   1528篇
  1993年   914篇
  1992年   1293篇
  1991年   1117篇
  1990年   905篇
  1989年   845篇
  1988年   766篇
  1987年   627篇
  1986年   459篇
  1985年   398篇
  1984年   191篇
  1983年   162篇
  1982年   94篇
  1981年   123篇
  1980年   79篇
  1979年   109篇
  1978年   52篇
  1977年   51篇
  1976年   42篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
杨青香 《护理研究》2006,20(25):2290-2291
代谢综合征(metabolic syndrome,MS)是包括多种代谢紊乱的一组病理综合征。这些代谢紊乱之间具有密切而复杂的相互关系,是造成包括高血压病、糖尿病、心脑血管疾病在内的一组疾病的基础。MS患病率在世界范围内正以极快的速度增长,预防和治疗MS相关疾病的发生和发展,是目前备受关注的重大社会卫生问题[1]。笔者对119例MS病人进行MS认知程度的调查,分析影响MS病人治疗依从性的因素。1对象和方法1.1对象2003年6月—2005年6月我院内分泌科住院和门诊MS病人119例,均符合中华糖尿病学分会CDS(2004)MS诊断标准[2]。所有病人思维清晰,语言表…  相似文献   
102.
LHRH-PE40识别结肠癌细胞膜表面蛋白的研究   总被引:1,自引:0,他引:1  
目的探讨人结肠癌细胞系Lovo及人白血病细胞系Jurket细胞膜表面蛋白能否识别LHRH-PE40及是否存在竞争性抑制。方法将结肠癌细胞系Lovo及白血病细胞系Jurket制备成细胞膜,利用125I标记的LHRH-PE40与两种细胞膜进行放射性配基分析,与LHRH进行竞争结合分析。结果人结肠癌细胞系Lovo的结合竞争符合特异性配基-受体结合、竞争;而白血病细胞系Jurket未见配基-受体特异性结合。其中LHRH-PE40与Lovo细胞的亲和力:Kd=10·6±2·33nmol/L,容量Bmax=345±7·59pmol/mg。结论LHRH是结肠癌免疫治疗的有效靶点,LHRH-PE40对过度表达LHRH受体的结肠癌具有特异性杀伤作用,而对无LHRH表达的肿瘤无杀伤作用,对于药物的临床应用有着指导意义。  相似文献   
103.
PURPOSE: Perineural invasion is a frequent occurrence in salivary adenoid cystic carcinoma (ACC) and may prevent complete surgical resection. Studies have indicated that nerve growth factor (NGF) and its high-affinity receptor tyrosine kinase A (TrkA) may play a role in perineural invasion in several malignancies in which perineural invasion is observed. The present study was conducted to investigate the expression of NGF and TrkA in salivary ACC and to examine the effects of NGF on adhesion, migration and invasion capacities of a salivary ACC cell line (SACC-83) in vitro. PATIENTS AND METHODS: Expression of NGF and TrkA was explored using immunohistochemistry in paraffin-embedded tissues of 32 cases of salivary ACC. The effects of NGF on in vitro adhesion, migration, and invasion capacities of the SACC-83 cell line were examined using an MTT assay and a modified Boyden chamber assay respectively. RESULTS: In ACC specimens, 31 (96.9%) and 32 (100%) tumors showed immunoreactivity for NGF and TrkA respectively. Significant correlations were found between NGF/TrkA expression levels and perineural invasion (P < .05). In cell adhesion assay, the percent adherences of SACC-83 cells co-cultured with 25 ng/ml NGF at 1.5 hours and 5, 25 ng/ml NGF at 6 hours were significantly higher than that co-cultured with 0 ng/ml NGF (P < .05). However, high concentration of NGF (500 ng/ml) resulted in a significant inhibition of invasion (P < .05). CONCLUSION: Overexpression of NGF and TrkA in human salivary ACC tissues may constitute a reason for perineural invasion in salivary ACC.  相似文献   
104.
105.
本文对1984年1~3月和1985年3~8月共107例急性下呼吸道感染的住院患儿,采用间接免疫荧光法检测其急性期血清抗RSV特异性IgM抗体,并与病毒分离和/或中和试验比较,敏感性为82.1%,特异性为71.8%。RSV感染患儿发病后3天内大多数病例即可从血清中检测出RSV-IgM,因此该法具有早期诊断价值。  相似文献   
106.
107.
The purpose of investigation was to study the effect of intrathecal fentanyl on the onset and duration of hyperbaric bupivacaine-induced spinal block in adult male patients. Fortythree patients undergoing lower extremity or genitourinary surgery were enrolled to receive either 13.5 mg hyperbaric bupivacaine 0.75% + 0.5 ml CSF it, (Group I) or 13.5 mg hyperbaric bupivacaine 0.75% + 25 μg fentanyl it, (Group II) according to a randomized assessor-blind protocol. The onset and duration of sensory block were assessed by pinching the skin with forceps in the midclavicular line bilaterally every two minutes for first twenty minutes and then every five to ten minutes. Similarly, the onset and duration of motor block were assessed and graded at the same time intervals using the criteria described by Bromage. The time required for two sensory segment regression and sensory regression to L1 dermatome was 74 ± 18 and 110 ± 33 min vs 93 ± 22 and 141 ± 37 min in Groups I and II, respectively (P < 0.05). Intrathecal fentanyl did not enhance the onset of sensory or motor block, or prolong the duration of bupivacaine-induced motor spinal block. Fewer patients demanded pain relief in the fentanyl-treated group than in the control group in the early postoperative period (19% vs 59%; P < 0.05). Episodes of hypotension were more frequent in the fentanyl-treated group than in the control group (43% vs 14%; P < 0.05). We conclude that fentanyl, 25 μg it, prolonged the duration of bupivacaine-induced sensory block (sensory regression to L1 dermatone) by 28% and reduced the analgesic requirement in the early postoperative period following bupivacaine spinal block.  相似文献   
108.
雷公藤双层栓的研制   总被引:7,自引:0,他引:7  
介绍了雷公藤双层栓的制备和质量检查。雷公藤双层栓的上层为空白层,下层为含药层。空白层可有效地阻止后端所释药物向上扩散,从而避免相当部分药物经门肝系统吸收,因此可明显提高其生物利用度。  相似文献   
109.
本文报告动脉粥样硬化(AS)形成和消退研究的部分工作。在复制AS形成和消退模型的基础上,研究了AS形成和消退中的内皮细胞、平滑肌细胞和单核细胞的改变。  相似文献   
110.
R.R Fiscus  L Lu  A.W.K Tu  H Hao  L Yang  X Wang 《Neuropeptides》1998,32(6):499-509
Calcitonin gene-related peptide (CGRP) causes vasorelaxation in rat aorta involving endothelium/nitric oxide (NO)-dependent elevations of both cAMP and cGMP levels. When endothelium is removed, preincubation with exogenous NO uncovers and potentiates direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP. This enhancing effect of NO potentially involves elevation of cGMP and inhibition of Type III (cGMPinhibitable) phosphodiesterase, causing accumulation of cAMP. However, NO may have other actions. The aim of the present study was to determine if brain natriuretic peptide (BNP), which elevates cGMP levels independent of NO, could enhance cAMP accumulations and vasorelaxations induced by CGRP in rat aortic rings denuded of endothelium. When added separately, neither CGRP (100 nM) nor BNP (10 nM) altered cAMP levels. When added in combination, CGRP (100 nM) and BNP (10 nM) significantly elevated cAMP levels (from control of 0.95 ± 0.08 to 1.53 ± 0.09 pmol/mg protein) at 2 min. BNP (10 nM) elevated cGMP levels 10-fold at 2 min and this response was not altered by co-administration of CGRP (100 nM).Pretreatment with BNP at concentrations as low as 1 nM in endothelium-denuded aortic rings greatly enhanced the direct vasorelaxant effects of CGRP (100 nM) (from control of 0% to 57.6 ± 6.8% relaxation of phenylephrineprecontractions). Our findings indicate that BNP enhances direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP in rat aorta, thus supporting the concept that cGMP inhibits cAMP metabolism and enhances CGRP-induced responses in aortic smooth muscle cells.  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