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   11338篇
  免费   707篇
  国内免费   129篇
耳鼻咽喉   195篇
儿科学   74篇
妇产科学   135篇
基础医学   2071篇
口腔科学   325篇
临床医学   945篇
内科学   1841篇
皮肤病学   453篇
神经病学   1040篇
特种医学   636篇
外科学   1568篇
综合类   37篇
一般理论   2篇
预防医学   455篇
眼科学   277篇
药学   1241篇
中国医学   153篇
肿瘤学   726篇
  2024年   3篇
  2023年   52篇
  2022年   228篇
  2021年   477篇
  2020年   200篇
  2019年   306篇
  2018年   358篇
  2017年   276篇
  2016年   389篇
  2015年   504篇
  2014年   650篇
  2013年   730篇
  2012年   1051篇
  2011年   983篇
  2010年   626篇
  2009年   530篇
  2008年   751篇
  2007年   741篇
  2006年   644篇
  2005年   566篇
  2004年   450篇
  2003年   385篇
  2002年   314篇
  2001年   220篇
  2000年   188篇
  1999年   130篇
  1998年   59篇
  1997年   45篇
  1996年   31篇
  1995年   27篇
  1994年   20篇
  1993年   17篇
  1992年   34篇
  1991年   32篇
  1990年   31篇
  1989年   22篇
  1988年   16篇
  1987年   16篇
  1986年   8篇
  1985年   8篇
  1984年   10篇
  1983年   3篇
  1982年   4篇
  1981年   4篇
  1979年   7篇
  1978年   5篇
  1977年   5篇
  1976年   5篇
  1969年   2篇
  1968年   3篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
荧光分光光度法检测裸鼠移植瘤组织中阿霉素浓度   总被引:3,自引:0,他引:3  
目的建立裸鼠移植瘤组织中阿霉(Dox)素浓度的荧光分光光度法检测方法。方法建立KB、KBv200细胞裸鼠移植瘤模型,经鼠尾静脉给予不同剂量阿霉素,3h后,处死裸鼠,分离及匀浆肿瘤组织,用含0.3mol·L-1HCl的60%乙醇抽提,离心取上清液,用荧光分光光度计在λex/em为470/590nm测定其荧光值,通过标准曲线方程计算阿霉素浓度。结果样本扫描未见杂峰,日内精密度<6.4%,日间精密度小于5.7%,阿霉素于肿瘤组织匀浆中抽提回收率>75.9%,KB细胞移植瘤组织中阿霉素浓度为KBv200的2.53~4.54倍。结论本方法专属性高,快速、简便,结果准确可靠,适用于裸鼠移植瘤组织中Dox药代动力学研究。  相似文献   
102.
A co-operative study was conducted to determine the clinical characteristics of patients with moyamoya disease who were diagnosed and treated at neurosurgical institutes in Korea before 1995. Twenty-six hospitals contributed 505 cases and among them, the clinical characteristics of 334 patients with definite moyamoya disease were evaluated. The number of patients began to increase from the late 1980s, and after that approximately 20 patients were treated each year. There were two age peaks: from six to 15 and from 31 to 40 years of age. Haemorrhagic manifestations occurred in approximately 43% of the patients. The major clinical manifestations were haemorrhage in adults (62.4%) and ischaemia in children (61.2%). Overall 54.5% of the patients experienced decreased consciousness levels, mainly due to intracranial haemorrhage or cerebral infarction. In the patients with ischemic manifestations, the adult patients were more likely to have cerebral infarction than the pediatric patients (80% vs. 39%) and the pediatric patients were more likely to have TIA (61% vs. 25%). Thirty eight percent of the patients underwent bypass surgery and 53% of these procedures were performed bilaterally. Treatment policies, including indications for bypass surgery and commonly used drugs, were somewhat different according to the institution. Overall favorable outcome was 73%, and the most significant factor affecting poor outcome was haemorrhagic manifestation. This article describes the characteristics of 334 patients with moyamoya disease, who were diagnosed and treated at neurosurgical institutes in Korea before 1995.  相似文献   
103.
Intrinsic signal imaging (ISI) measures changes in light reflectance from the illuminated cortex (intrinsic signals or IS) attributed to various vascular and metabolic sources that, when using illumination in the 600 nm range, appear to co-localize with neuronal activity. Given the multiple sources contributing to the collected IS, the common practice of averaging across an extended post-stimulus time epoch before dividing by baseline data typically visualizes evoked IS overlying both the cortical tissue and the large surface blood vessels. In rat PMBSF, the contribution from these vessels are problematic as they do not co-localize with known PMBSF function. Determining a means for quantifying the evoked IS area poses an additional challenge. Here, we describe how exploiting IS collected shortly after stimulus onset (within 1.5 s), which coincides with fast oxygen consumption of active neurons, visualizes evoked IS overlying the cortical tissue without the large surface vessels. We also describe how the use of absolute thresholds combined with a baseline determined from data collected immediately prior to stimulus onset (within 1 s) targets most precisely a specific evoked IS amplitude, a method that should be especially useful when evoked areas are expected to occupy a substantial portion of the total imaged area and/or when peak activity is expected to differ between subjects.  相似文献   
104.
Pituitary adenylate cyclase-activating polypeptide (PACAP) regulates pituitary hormone biosynthesis and secretion through its cognate receptors. PACAP also plays an important role in the regulation of ovarian steroid biosynthesis. If so, there might be a feedback regulation of hypothalamic PACAP synthesis by the pituitary and by ovarian steroids. In the present study, we used RNase protection assays to determine changes in mRNA levels of PACAP and type I PACAP receptor (PAC(1)) under the conditions of ovariectomy and replacement with ovarian steroids. Progesterone (P) alone or in combination with estradiol (E) induced significant increases in PACAP mRNA level in the medial basal hypothalamus (MBH) and PAC(1) mRNA levels in MBH and the preoptic area (POA). This finding suggests that feedback regulation takes place between the ovary and hypothalamic PACAP neurons. P is known to be a major regulatory feedback factor for hypothalamic luteinizing hormone-releasing hormone (LHRH) neurons, but P receptor is not present in these neurons. Therefore, we examined a possible involvement of PACAP in the feedback regulatory pathway of P to LHRH neurons. After an antisense PAC(1) oligodeoxynucleotide (ODN) was i.c.v.-injected into the third ventricle of E and P-treated rats, LHRH mRNA levels were determined. The ODN markedly decreased the P-induced increase in the LHRH mRNA level. Taken together, the present data suggest that PACAP may play a role as a mediator in the regulation of LHRH synthetic machinery by stimulatory feedback of P.  相似文献   
105.
目的 探讨MTS法细胞毒试验的细胞数 OD关系以及药物剂量 -抑制率关系 ,为更好地应用MTS法提供提示。方法 采用HL 6 0和Raji细胞株。细胞数 OD关系试验 :96孔板接种不同浓度的细胞 ,加入MTS培养 1~ 5h后于 4 90nm波长测定OD ,用SPSS 11 0软件对数据作曲线估计。细胞毒试验 :96孔板每孔接种细胞 ,加不同剂量的药物培养 72h ,加入MTS培养 3h后于 4 90nm波长测定OD ,用SPSS11 0软件对数据作曲线估计。结果  2种细胞 5个时间点的细胞数 OD关系以三次项曲线拟合度最好 ,r2 为 0 997~1 0 0 0 ,均大于线性模型的r2 0 938~ 0 993。 3种药物对 2种细胞的剂量 -抑制率以三次项曲线拟合度最好 ,r2 为0 998~ 1 0 0 0 ,优于对数剂量 -概率单位线性模型的r20 94 8~ 0 987。结论 三次项曲线对MTS法细胞毒试验的细胞数 OD关系有很高拟合度且优于线性曲线模型。通过药物剂量 -抑制率的三次项曲线拟合方程可望得到比常用的概率单位回归法更准确的IC50 。  相似文献   
106.
107.
Targeted application of next-generation sequencing (NGS) technology allows detection of specific mutations that can provide treatment opportunities for cancer patients. We evaluated the applicability of the Ion AmpliSeq Cancer Hotspot Panel V2 (CHV2) using formalin-fixed, paraffin-embedded (FFPE) tissue of clinical specimens.Thirty-five FFPE tumour samples with known mutational status were collected from four different hospitals and sequenced with CHV2 using an Ion Chef System and Ion S5 XL system. Out of 35 cases, seven were sequenced with Oncomine focus Assay Panel for comparison. For the limit of detection test, we used an FFPE reference standard, a cell line that included an engineered 50% EGFR T790?M in an RKO cell line background. Coverage analysis results including number of mapped reads, on target percent, mean depth, and uniformity were not different according to hospitals. Sensitivity for mutation detection down to 3% was demonstrated. NGS results showed 100% concordance with the results from single molecular pathology tests Assay in 30 cases with 24 known positive mutations and 14 known negative mutations, and another NGS panel of the Oncomine focus in seven cases.The CHV2 NGS test for solid tumours using Ion chef system and S5 XL system in clinical molecular pathology laboratories for analysis of solid tumours could be routinely used and could replace some single molecular pathology tests after a stringent and thorough validation process.  相似文献   
108.
109.
This study translated the Depressive Cognition Scale (DCS) from English into Korean and tested the reliability and validity of the scale. Data were from a convenient sample of 795 community-dwelling Korean adults with a self-administered questionnaire. With regard to the reliability estimate, the internal consistency of the Korean version of the DCS (K-DCS) was acceptable, where the Chronbach's alpha is .93 and the average item-to-total correlation r = .760. With regard to the validity estimate, the mean scores of the K-DCS were significantly different according to gender, age, and marital status. A single factor was extracted that accounted for 67.37% of the total variance. The average score of the K-DCS also correlated significantly with the subscales of the Korean version of the Profile of the Mood States Brief Form. These findings suggest that the K-DCS can be used as a reliable and valid measure of depressive cognition among Korean adults.  相似文献   
110.
We encountered an undescribed histologic feature of papillary urothelial neoplasms: “urothelial eddy”, which was histologically reminiscent of squamous eddy of irritated follicular keratosis of the skin. A review of 756 patients with transurethral resection of bladder tumor revealed 10 patients (1.3%) of papillary urothelial neoplasms with urothelial eddies. All cases were male with a median age of 65 years. Urothelial eddies were characterized by small ovoid nests of ovoid to spindle cells arranged in an onion-skin pattern with fine cytoplasmic processes within wide intercellular space. The cytoplasmic processes mimicked intercellular bridges but ultrastructurally were cytoplasmic microvillous projections. They were of papillary urothelial neoplasm of low malignant potential in seven patients and low-grade urothelial carcinoma in three patients. Nine patients presented as non-invasive tumor and one patient showed microinvasion within papillary stalks. Six patients showed an inverted growth pattern. Their immunoprofile was more similar to that of conventional urothelial carcinoma rather than squamous cell carcinoma: high expressions of GATA3, S100P, uroplakin III, and cytokeratin 7; and low expressions of high molecular weight cytokeratin and p53. The Ki-67 labeling index was low (mean and median values, 2% each). During the follow-up period (mean, 88.7 months), four patients, including the microinvasive patient, showed recurrence with the same grade and stage but neither progressed into muscle-invasive tumor nor caused death. Our results suggest that urothelial eddy is a rare aberrant histology of papillary urothelial neoplasms with indolent behavior and should be discriminated from squamous differentiation of urothelial carcinoma, which has a poor prognosis.  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