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   9349篇
  免费   447篇
  国内免费   858篇
耳鼻咽喉   106篇
儿科学   111篇
妇产科学   153篇
基础医学   1612篇
口腔科学   124篇
临床医学   534篇
内科学   1836篇
皮肤病学   107篇
神经病学   484篇
特种医学   192篇
外科学   865篇
综合类   1086篇
现状与发展   19篇
一般理论   10篇
预防医学   577篇
眼科学   392篇
药学   996篇
  2篇
中国医学   214篇
肿瘤学   1234篇
  2024年   24篇
  2023年   111篇
  2022年   85篇
  2021年   62篇
  2020年   38篇
  2019年   27篇
  2018年   43篇
  2017年   27篇
  2016年   28篇
  2015年   40篇
  2014年   115篇
  2013年   72篇
  2012年   1589篇
  2011年   1773篇
  2010年   317篇
  2009年   130篇
  2008年   964篇
  2007年   904篇
  2006年   830篇
  2005年   814篇
  2004年   661篇
  2003年   536篇
  2002年   422篇
  2001年   249篇
  2000年   308篇
  1999年   170篇
  1998年   97篇
  1997年   25篇
  1996年   12篇
  1995年   9篇
  1994年   6篇
  1993年   5篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   20篇
  1988年   14篇
  1987年   13篇
  1986年   9篇
  1985年   20篇
  1984年   26篇
  1983年   13篇
  1982年   15篇
  1981年   13篇
  1980年   3篇
  1979年   4篇
  1977年   1篇
  1976年   1篇
  1964年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
目的观察高位硬膜外麻醉和全麻异氟烷吸入在婴幼儿动脉导管未闭(PDA)手术降压中的临床应用。方法将40例患儿分为2组:高位硬膜外麻醉组(20例)和全麻异氟烷吸入组(20例),观察比较2组的降压效果。结果2组降压效果比较差异无统计学意义(P>0.05),高位硬膜外麻醉组在手术结束时心血管指标恢复平稳,与全麻异氟烷吸入组相比,差异有统计学意义(P<0.05),而且拔管时间明显缩短。结论2种降压方法均可行控制性降压,高位硬膜外麻醉使婴幼儿心血管反应更加稳定,对循环系统的扰乱程度轻,保护了婴幼儿的应激反应。  相似文献   
92.
Objective: To investigate the distribution of TRPA1 (one kind of the TRP-like ion channel family) channel in the hippocampus and cerebral cortex of rat. Methods: RT-PCR was used to amplify the fragment of TRPA1 in the DRG (dorsal root ganglion), hippocampus and cerebral cortex of adult SD rat. In situ hybridization staining was used to show the distribution of TRPA1 mRNA in the hippocampus and cerebral cortex of adult rat brain. Results: Both RT-PCR and in situ hybridization staining showed that TRPA1 mRNA was expressed in hippocampus and cerebral cortex of the adult rat brain. Conclusion: Our results suggest that there is expression of TRPA1 mRNA both in the hippocampus and cerebral cortex of the adult rat brain.  相似文献   
93.
OBJECTIVE: To study alterations of serum levels of the pancreatic reg family of proteins in two models of acute pancreatitis. SUMMARY BACKGROUND DATA: The pancreatic reg family of proteins is expressed in the acinar pancreas. Reg I (pancreatic stone protein, PSP) and reg III (pancreatitis-associated protein, PAP) are induced after the onset of acute pancreatitis, and both have been proposed as potential markers of pancreatitis. METHODS: Pancreatitis was induced in rats by either retrograde infusion of sodium taurocholate or by direct trauma. Serum samples were obtained daily for 4 days after the procedure, and the animals were then killed. Twelve animals underwent sham procedure and six underwent daily analysis without surgery. Levels of reg I/PSP and reg III/PAP were estimated by enzyme-linked immunosorbent assay. RESULTS: Reg III/PAP levels increased significantly the first day after induction of both types of pancreatitis and rapidly returned to baseline in all survivors. Even animals who received retrograde infusion of saline showed a mild increase in reg III/PAP on the first day, whereas control animals that did not undergo surgery showed no variations. Reg I/PSP serum levels remained unchanged throughout all experimental periods. Postinjury reg III/PAP levels significantly correlated with severity of the pancreatic injury and animal survival; reg I/PSP levels did not. CONCLUSION: After induction of pancreatitis, serum levels of reg I and III protein differ significantly. Reg III/PAP levels are a sensitive marker of pancreatic injury and early in the disease may be a useful prognostic indicator for disease severity.  相似文献   
94.
AIM: To investigate the expression and role of calcitonin gene-related peptide (CGRP) in the mouse models induced by Aspergillus fumigatus (A. fumigatus). METHODS: C57BL/6 mice were randomized into a control group and A. fumigatus keratitis group. The cornea photography was assessed under the slit lamp and the clinical score was recorded after infection. Western blot, real-time polymerase chain reaction (PCR) and immunohistofluorescence analysis were applied to detect CGRP expression in cornea of both groups. In vitro, tests were conducted with C57BL/6 mice macrophages to investigate CGRP expression after interaction with A. fumigatus. Cytokines expression induced by exogenous CGRP and the antagonist CGRP8-37 in A. fumigatus-exposed macrophages was evaluated by real-time PCR and ELISA. RESULTS: The cornea expression of CGRP was significantly elevated in C57BL/6 mice corneas and macrophages after A. fumigatus infection. After treatment with exogenous CGRP, the levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and IL-6 were reduced, and IL-10 level was increased in the A. fumigatus stimulated-macrophages. However, IL-1β, TNF-α and IL-6 levels were upregulated after pretreatment of CGRP8-37. But the mRNA levels of MIP-2, TGF-β and IL-10 were not changed. CONCLUSION: This study provides evidence that A. fumigatus increased CGRP expression. CGRP may play a protective role against inflammation in A. fumigatus keratitis.  相似文献   
95.
To evaluate the maneuverability and efficacy of phacoemulsification and intraocular lens (IOL) implantation in eyes with corneal opacities after deep anterior lamellar keratoplasty (DALK), twelve eyes of 12 patients with mild to moderate corneal opacities after DALK and coexisting cataracts were analyzed retrospectively. Phacoemulsification and IOL implantation assisted with anterior capsule staining, as well as non-invasive optical fiber illumination, were performed on all eyes. No intraoperative or postoperative complications were noted. Mean corrected distance visual acuity (logMAR) improved from 1.24±0.17 to 0.73±0.22. Post-phaco intraocular pressure was maintained between 13 to 20 mm Hg in all cases throughout the follow-up period. Mean endothelial cell density decreased from 2258.42±205.94 to 1906.25±174.23 cells/mm2. Phacoemulsification and IOL implantation are safe and valid in eyes with mild to moderate corneal opacities after DALK and coexisting cataracts when assisted with anterior capsule staining and non-invasive optical fiber illumination.  相似文献   
96.
Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.  相似文献   
97.
Objective:To investigate the network pharmacology of anti-tumor Chinese medicinal formulae and explain the synergistic mechanism of various active ingredients of Chinese medicinal formulae.Methods:We collected the anti?tumor Chinese medicinal formulae and chose several single herbs with the top frequency for further study.The chemical constituents of these herbs were downloaded from databases CNPC and Traditional Chinese Medicine Systems Pharmacology and were analyzed to set up the anti-tumor material basis.The genes regulated by these constituents were retrieved in Traditional Chinese Medicine integrated database and Comparative Toxicogenomics database.Results:We collected 65 anti-tumor Chinese medicinal formulae,and 4 single herbs were selected,including Licorice,Radix astragali,Panax ginseng,and Radix scutellariae,which consist of 172,70,293,and 92 known constituents,respectively.The constituent–gene network,protein–protein interaction network,gene–pathway enrichment network,and gene–disease network were constructed.Moreover,molecular docking was employed to clarify the interactions between active constituents and key drug targets(PTG2,epidermal growth factor receptor,peroxisome proliferator?activated receptor gamma,estrogen receptor 1,mammalian target of rapamycin,AKT1,mitogen-activated protein kinase 1 [MAPK1],peroxisome proliferator-activated receptor alpha,and MAPK8).Most of the constituents could act on multiple targets,whose structures mainly belong to alkaloids,flavonoids,and their glycosides,organic acids,or dianthrone,and their representative chemical constituents include narcissus glycosides,rutin,dauricine,scutellarin,baicalin,isoschaftoside,and leucovorin.Conclusion:The network mechanism of the effective constituents from traditional Chinese medicines(TCMs) for anti-tumor therapy was partially uncovered by using statistical methods,network pharmacology methods,and molecular docking methods.This study will provide important information for new drug design with multiple targets for anti-tumor therapy.  相似文献   
98.
有越来越多的医生选择学习在线课程来进行继续医学教育,但却很少有严格的评估方法来确定在线继续医学教育活动的效果.鉴于此,美国阿拉巴马大学医学院继续医学教育部的研究人员进行了相关研究.应用时间序列设计的方法,来比较完成了继续医学教育网站提供的任意30分钟在线继续医学教育课程的医生在教育活动前后其知识、态度和自我报告的在临床实践中诊疗行为的变化.  相似文献   
99.
Objective: The differences of ovarian morphology, reproductive hormones, glucose and lipid metabolism and intestinal bacteria in rats with polycystic ovary syndrome (PCOS) induced by triazole were compared. Method: Eighteen 21 SPF female SD rats were randomly divided into group A (3-week group), group B (5-week group) and group D (control group) by random number table.Group A received letrozole + CMC-Na mixture by gavage in the first 3 weeks and CMC-Na solution by gavage in the last 2 weeks, group B received letrozole + CMC-Na mixture by gavage for 5 weeks, and group D received CMC-Na solution by gavage for 5 weeks, and all three groups of rats were fed with normal diet.At the end of gavage, the body weight of rats in each group was observed, the histological changes of ovaries were observed by hematoxylin-eosin (HE) staining, the serum levels of estradiol (E2), follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), total cholesterol (TC), triglyceride (TG), fasting blood glucose (Glu), fasting insulin (FINS) and lipopolysaccharide (LPS) were measured by enzyme-linked immunosorbent assay (ELISA), and the LH/FSH ratio and insulin resistance index (HOMA IR) were calculated; the intestinal bacteria of rats were detected by 16S rRNA technique. Result: 1. Comparison of ovary histomorphology: Under light microscope, multiple luteum and oocytes were observed in mature follicles in group D, and granulosa cells were orderly arranged and multilayered, without cystic dilated follicles. There were no mature follicles in the ovarian tissues of group A and GROUP B. The follicles were irregular in structure and more cystic dilated follicles were visible. The number of granular cells in some follicles decreased or even disappeared. 2. Comparison of sex hormone levels: compared with group D, T level in group B was significantly increased (P < 0.001), and T level in group A had an upward trend (P > 0.05); The LH/FSH levels in group A and B were significantly increased (P < 0.001; P < 0.001). Compared with group A, E2 in group B was significantly decreased (P < 0.05) and T was significantly increased (P < 0.01). 3. Comparison of glucose and lipid metabolism levels: Compared with group D, TC levels in groups A and B were significantly increased (P < 0.01; P < 0.01). Compared with group A, TG in group B was significantly increased (P < 0.05). There were no significant differences in Glu, FINS and HOMA-IR levels among all groups. 4. Comparison of LPS levels: Compared with group D, the serum LPS levels of rats in groups A and B were significantly increased (P < 0.001; P < 0.01). 5. Intestinal flora analysis and comparison: At the phylum level, compared with group D, the abundance of Firmicutes in group B increased (P < 0.01), Firmicutes in group A showed an upward trend (P > 0.05), and the abundance of Bacteroidetes in groups A and B decreased (P < 0.05). At the genus level, compared with group D, Lactobacillus in group B increased (P < 0.01). The results of LEfSe analysis showed that there were differences in the composition of various intestinal bacteria among the three groups (LDA > 3).Conclusion: The phenotype of PCOS rats was related to the length of modeling, and the phenotypic characteristics of PCOS in rats at 5 weeks of modeling were more typical than those in rats at 3 weeks of modeling; PCOS can cause changes in intestinal flora, and the changes in the structure of intestinal flora between groups are related to different modeling duration.  相似文献   
100.
Neuroinflammation and the NACHT, LRR, and PYD domains-containing protein 3 inflammasome play crucial roles in secondary tissue damage following an initial insult in patients with traumatic brain injury(TBI). Maraviroc, a C-C chemokine receptor type 5 antagonist, has been viewed as a new therapeutic strategy for many neuroinflammatory diseases. We studied the effect of maraviroc on TBI-induced neuroinflammation. A moderate-TBI mouse model was subjected to a controlled cortical impact device. Mara...  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