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   276767篇
  免费   26088篇
  国内免费   11452篇
耳鼻咽喉   1811篇
儿科学   6370篇
妇产科学   4020篇
基础医学   46261篇
口腔科学   5560篇
临床医学   20905篇
内科学   46087篇
皮肤病学   4421篇
神经病学   22613篇
特种医学   5370篇
外国民族医学   81篇
外科学   20851篇
综合类   38779篇
现状与发展   42篇
预防医学   15597篇
眼科学   4802篇
药学   33288篇
  47篇
中国医学   9675篇
肿瘤学   27727篇
  2024年   471篇
  2023年   3816篇
  2022年   5761篇
  2021年   10839篇
  2020年   9338篇
  2019年   10046篇
  2018年   9654篇
  2017年   9882篇
  2016年   10021篇
  2015年   11360篇
  2014年   16926篇
  2013年   18944篇
  2012年   17455篇
  2011年   20264篇
  2010年   17136篇
  2009年   16313篇
  2008年   15938篇
  2007年   14866篇
  2006年   13460篇
  2005年   11641篇
  2004年   10098篇
  2003年   8602篇
  2002年   6834篇
  2001年   5884篇
  2000年   4915篇
  1999年   4373篇
  1998年   3738篇
  1997年   3338篇
  1996年   2914篇
  1995年   2527篇
  1994年   2132篇
  1993年   1772篇
  1992年   1509篇
  1991年   1278篇
  1990年   1109篇
  1989年   889篇
  1988年   748篇
  1987年   604篇
  1986年   577篇
  1985年   1034篇
  1984年   1016篇
  1983年   690篇
  1982年   809篇
  1981年   603篇
  1980年   527篇
  1979年   430篇
  1978年   323篇
  1977年   253篇
  1976年   233篇
  1975年   165篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
目的:研究PTPN6对前列腺癌细胞PC3的作用及其作用机制。方法:RT-PCR和Western blot实验检测前列腺癌组织和细胞以及癌旁组织和人前列腺上皮细胞中PTPN6的表达量;CCK-8和EDU染色实验检测PTPN6对前列腺癌细胞PC3增殖的影响;Western blot实验检测耐药相关蛋白P-gp和MRP-1的蛋白表达水平。结果:RT-PCR和Western blot结果显示,PTPN6在前列腺癌组织和细胞中的表达量显著低于癌旁组织和人前列腺上皮细胞中的表达量;过表达PTPN6显著抑制前列腺癌PC3细胞的增殖,并降低PC3细胞的耐药性;进一步的研究结果表明PTPN6可通过抑制SP1,并抑制p38 MAPK通路抑制PC3细胞的增殖和耐药。结论:PTPN6能够抑制前列腺癌细胞PC3的增殖和耐药,提高其化疗敏感性,作用机制是通过调控SP1/p38 MAPK信号通路来实现的,这一结果能够为临床上前列腺癌的诊断和治疗提供分子基础。  相似文献   
92.
Attachment is a behavioral and physiological system, which enables individual’s dynamic adaptation to its environment. Attachment develops in close interaction between an infant and his/her mother, plays an important role in the development of the infant’s brain, and influences the quality of interpersonal relationships throughout life.Security of attachment is believed to influence individual response to stress, exposing insecurely organized individuals to deregulated autonomic nervous system and exaggerated hypothalamic-pituitary-adrenal activity, which, in turn, produces increased and prolonged exposure to stress-hormones. Such stress responses may have considerable implications for the development of diverse health-risk conditions, such as insulin resistance and hyperlipidemia, shown by numerous studies.Although the mechanisms are not yet fully understood, there is compelling evidence highlighting the role of psychological stress in the development of type 1 diabetes (T1D). One of the possible contributing factors for the development of T1D may be the influence of attachment security on individual stress reactivity. Thus, the suggestion is that insecurely attached individuals are more prone to experience increased and prolonged influence of stress hormones and other mechanisms causing pancreatic beta-cell destruction.The present paper opens with a short overview of the field of attachment in children, the principal attachment classifications and their historic development, describes the influence of attachment security on individual stress-reactivity and the role of the latter in the development of T1D. Following is a review of recent literature on the attachment in patients with T1D with a conclusion of a proposed role of attachment organization in the etiology of T1D.  相似文献   
93.
Ceramide synthases (CerS) synthesise ceramides of defined acyl chain lengths, which are thought to mediate cellular processes in a chain length-dependent manner. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), we observed a significant elevation of CerS2 and its products, C24-ceramides, in CD11b+ cells (monocytes and neutrophils) isolated from blood. This result correlates with the clinical finding that CerS2 mRNA expression and C24-ceramide levels were significantly increased by 2.2- and 1.5-fold, respectively, in white blood cells of MS patients. The increased CerS2 mRNA/C24-ceramide expression in neutrophils/monocytes seems to mediate pro-inflammatory effects, since a specific genetic deletion of CerS2 in blood cells or a total genetic deletion of CerS2 significantly delayed the onset of clinical symptoms, due to a reduced infiltration of immune cells, in particular neutrophils, into the central nervous system. CXCR2 chemokine receptors, expressed on neutrophils, promote the migration of neutrophils into the central nervous system, which is a prerequisite for the recruitment of further immune cells and the inflammatory process that leads to the development of MS. Interestingly, neutrophils isolated from CerS2 null EAE mice, as opposed to WT EAE mice, were characterised by significantly lower CXCR2 receptor mRNA expression resulting in their reduced migratory capacity towards CXCL2. Most importantly, G-CSF-induced CXCR2 expression was significantly reduced in CerS2 null neutrophils and their migratory capacity was significantly impaired. In conclusion, our data strongly indicate that G-CSF-induced CXCR2 expression is regulated in a CerS2-dependent manner and that CerS2 thereby promotes the migration of neutrophils, thus, contributing to inflammation and the development of EAE and MS.  相似文献   
94.
95.
Background: Dense deposit disease and atypical hemolytic uremic syndrome are often caused by Complement Factor H (CFH) mutations. This study describes the retinal abnormalities in dense deposit disease and, for the first time, atypical haemolytic uremic syndrome. It also reviews our understanding of drusen pathogenesis and their relevance for glomerular disease. Methods: Six individuals with dense deposit disease and one with atypical haemolytic uremic syndrome were studied from 2 to 40 years after presentation. Five had renal transplants. All four who had genetic testing had CFH mutations. Individuals underwent ophthalmological review and retinal photography, and in some cases, optical coherence tomography, and further tests of retinal function. Results: All subjects with dense deposit disease had impaired night vision and retinal drusen or whitish-yellow deposits. Retinal atrophy, pigmentation, and hemorrhage were common. In late disease, peripheral vision was restricted, central vision was distorted, and there were scotoma from sub-retinal choroidal neovascular membranes and atypical serous retinopathy. Drusen were present but less prominent in the young person with atypical uremic syndrome due to a heterozygous CFH mutation. Conclusions: Drusen are common in forms of C3 glomerulopathy caused by compound heterozygous or heterozygous CFH mutations. They are useful diagnostically but also impair vision. Drusen have an identical composition to glomerular deposits. They are also identical to the drusen of age-related macular degeneration, and may respond to the same treatments. Individuals with a C3 glomerulopathy should be assessed ophthalmologically at diagnosis, and monitored regularly for vision-threatening complications.  相似文献   
96.
97.
目的:探讨单孔胸腔镜下肺癌手术术后胸腔引流时间的影响因素。方法:本研究采用回顾性分析方法,回顾我院2018年01月至2019年12月原发性肺癌患者经单孔胸腔镜手术治疗的病例199例。按照术后胸腔引流时间分为两组,Ⅰ组(术后胸腔引流时间<5天)和Ⅱ组(术后胸腔引流时间≥5天)。对于影响术后胸腔引流时间的可能因素在两组间先采用单因素分析的方法筛选,再将筛选出来的对术后胸腔引流时间可能有意义的影响因素进行二项Logistic多因素回归分析。结果:经单因素分析及二项Logistic多因素回归分析结果显示:年龄≥60岁、手术部位、肺段切除术、胸膜粘连、手术时间≥180 min、术后早期下床活动是术后胸腔引流时间的独立影响因素(P<0.05)。结论:对于具有多个延长术后胸腔引流时间的独立影响因素的患者,应制定个体化管理方案,尽可能减少术后胸腔引流时间,减少住院天数,加快患者康复。  相似文献   
98.
目的 探讨丹青胶囊联合他扎罗汀倍他米松治疗银屑病的临床疗效.方法 选取2019年6月—2021年6月在天津市职业病防治院门诊皮肤科就诊治疗的114例银屑病患者,根据随机数字法分为对照组和治疗组,每组各57例.对照组患者给予他扎罗汀倍他米松乳膏,洗净患处,待皮肤干爽后,将适量本品均匀涂抹于患处,1次/d.治疗组患者在对照组治疗基础上口服丹青胶囊,4粒/次,3次/d.两组患者均连续治疗7 d.观察两组患者的临床疗效和临床症状好转时间,比较两组治疗前与治疗1、4、8周的皮损面积和严重程度指数(PASI)评分和血清炎性因子水平.结果 治疗后,治疗组总有效率是98.25%,显著高于对照组的82.46%(P<0.05).治疗后,治疗组患者皮损暗红、皮损肥厚、皮肤瘙痒、皮肤疼痛等症状好转时间均显著短于对照组(P<0.05).治疗后,两组PASI评分均较治疗前显著降低(P<0.05);治疗1、4、8周治疗组PASI评分显著低于对照组(P<0.05).治疗后,两组患者血清炎性因子白细胞介素6(IL-6)、白细胞介素17(IL-17)、肿瘤坏死因子α(TNF-α)、干扰素-γ(IFN-γ)水平均较治疗前显著降低(P<0.05);治疗后,治疗组血清炎性因子水平显著低于对照组(P<0.05).结论 丹青胶囊联合他扎罗汀倍他米松治疗银屑病效果明显,能显著降低炎性因子水平,并有助于改善皮损情况,值得临床推广应用.  相似文献   
99.
ObjectiveTo investigate the association between type 1 diabetes mellitus (T1D) and type 2 diabetes mellitus (T2D) with risk of sudden cardiac arrest (SCA).MethodsIn a prospective community-based study of SCA from February 1, 2002, through November 30, 2019, we ascertained 2771 cases age 18 years of age or older and matched them to 8313 controls based on geography, age, sex, and race/ethnicity. We used logistic regression to evaluate the independent association between diabetes, T1D, T2D, and SCA.ResultsPatients had a mean age of 64.5±15.9 years, were 33.3% female and 23.9% non-White race. Overall, 36.7% (n=1016) of cases and 23.8% (n=1981) of controls had diabetes. Among individuals with diabetes, the proportion of T1D was 6.5% (n=66) among cases and 2.0% among controls (n=40). Diabetes was associated with 1.5-times higher odds of SCA. Compared with those without diabetes, the odds ratio and 95% CI for SCA was 4.36 (95% CI, 2.81 to 6.75; P<.001) in T1D and 1.45 (95% CI, 1.30 to 1.63; P<.001) in T2D after multivariable adjustment. Among those with diabetes, the odds of having SCA were 2.41 times higher in T1D than in T2D (95% CI, 1.53 to 3.80; P<.001). Cases of SCA with T1D were more likely to have an unwitnessed arrest, less likely to receive resuscitation, and less likely to survive compared with those with T2D.ConclusionType 1 diabetes was more strongly associated with SCA compared with T2D and had less favorable outcomes following resuscitation. Diabetes type could influence the approach to risk stratification and prevention of SCA.  相似文献   
100.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  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