全文获取类型
收费全文 | 48973篇 |
免费 | 4195篇 |
国内免费 | 1821篇 |
专业分类
耳鼻咽喉 | 312篇 |
儿科学 | 873篇 |
妇产科学 | 1363篇 |
基础医学 | 10174篇 |
口腔科学 | 1693篇 |
临床医学 | 3926篇 |
内科学 | 5349篇 |
皮肤病学 | 1269篇 |
神经病学 | 2947篇 |
特种医学 | 1079篇 |
外国民族医学 | 20篇 |
外科学 | 3321篇 |
综合类 | 7344篇 |
现状与发展 | 12篇 |
一般理论 | 12篇 |
预防医学 | 4054篇 |
眼科学 | 957篇 |
药学 | 5712篇 |
22篇 | |
中国医学 | 1094篇 |
肿瘤学 | 3456篇 |
出版年
2024年 | 68篇 |
2023年 | 516篇 |
2022年 | 1051篇 |
2021年 | 1517篇 |
2020年 | 1346篇 |
2019年 | 1376篇 |
2018年 | 1372篇 |
2017年 | 1494篇 |
2016年 | 1591篇 |
2015年 | 1620篇 |
2014年 | 2548篇 |
2013年 | 3489篇 |
2012年 | 2565篇 |
2011年 | 2843篇 |
2010年 | 2489篇 |
2009年 | 2286篇 |
2008年 | 2238篇 |
2007年 | 2417篇 |
2006年 | 2267篇 |
2005年 | 2058篇 |
2004年 | 1883篇 |
2003年 | 1707篇 |
2002年 | 1465篇 |
2001年 | 1269篇 |
2000年 | 1122篇 |
1999年 | 998篇 |
1998年 | 944篇 |
1997年 | 873篇 |
1996年 | 835篇 |
1995年 | 793篇 |
1994年 | 679篇 |
1993年 | 630篇 |
1992年 | 560篇 |
1991年 | 509篇 |
1990年 | 383篇 |
1989年 | 378篇 |
1988年 | 324篇 |
1987年 | 259篇 |
1986年 | 229篇 |
1985年 | 386篇 |
1984年 | 333篇 |
1983年 | 223篇 |
1982年 | 254篇 |
1981年 | 206篇 |
1980年 | 158篇 |
1979年 | 101篇 |
1978年 | 101篇 |
1977年 | 64篇 |
1976年 | 62篇 |
1975年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
181.
The influence of ethanol on the permeation of 17-estradiol (estradiol) across viable human skin in vivo was investigated with the human skin sandwich flap model. Maintaining continuous delivery of a constant concentration of the solute in phosphate-buffered saline, pH 7.4 (PBS), or mixtures of ethanol in PBS to the skin surface revealed that steady-state flux of estradiol was achieved within 30–60 min and maintained throughout 4 hr. The 10-fold decrease in in vivo flux and permeability coefficient (K
p) of tracer estradiol solutions in ethanol or ethanol solutions compared with PBS vehicle reflected the 10-fold difference in the apparent partition coefficients (K
m) of estradiol from the respective vehicles into isolated human stratum corneum. Neither the stratum corneum thickness nor the diffusion coefficient of estradiol was significantly different among the vehicles tested. In vivo flux of estradiol in ethanol or ethanol solutions across viable human skin was increased with saturated solutions of estradiol. Further, in vivo flux of estradiol from vehicles such as PBS, ethanol, and ethanol mixtures, which minimally alter the rate-limiting barrier, can be successfully predicted with knowledge of only two physicochemical parameters, the estradiol concentration in the vehicle and the K
m of estradiol from the vehicle into isolated human stratum corneum. 相似文献
182.
Samples of human allograft skin prepared without freezing ("fresh skin) were found to have electrical and sodium ion transport properties which differed only slightly from those of skin which had been similarly treated but stored frozen (frozen skin). The fresh skin samples were less permeable to sodium ions during passive diffusion and less conductive than frozen skin at low current levels. They were more permselective for sodium versus chloride during constant-current iontophoresis and showed slightly more asymmetry in their current–voltage properties. Overall, the electrical behavior of the two tissues was similar enough to support the use of frozen tissue in iontophoresis studies. However, caution should be exercised when considering the use of frozen skin for applications, such as those based on electroosmosis, where the observed differences could have a major impact on the results. 相似文献
183.
人巨细胞病毒感染与宫颈癌关系的研究 总被引:1,自引:0,他引:1
采用聚合酶链反应 (PCR)检测 30例宫颈癌、 30例宫颈炎、 8例正常宫颈组织标本中 HCMV早期 (IE)、晚期 (L)基因片段、 HCMV79- aa ORF癌基因及 HPV16、 18、 32、 5 2 b、 5 8型 DNA。结果表明 :除 HCMV L 基因外 ,以上各基因在宫颈癌组之检出率均显著高于宫颈炎组 ,且宫颈癌组 IE和 L 基因、HPV高危型和 HCMV同时感染的比值比 (OR)分别高于 IE或 L 基因、HPV高危型或 HCMV单独感染的 OR值之和。提示人巨细胞病毒与宫颈癌的发生有关 ,可通过其 IE基因启动、激活 HPV的致癌作用 ,HCMV79- aa ORF癌基因的整合也可能是致宫颈癌的一个不可忽视的重要因素 相似文献
184.
The development of the stria vascularis in the human cochlea was studied in step sections of 81 human foetal temporal bones. The stria vascularis primordium can be identified as a ridge of epithelial cells on the lateral wall of the cochlear duct. The first signs of differentiation appear at the 11th week, but it is not until the 17th–18th week that the typical trilaminar structure is observed. The appearance of similar cells with notched nuclei in both marginal and mesenchymal layers at this stage suggests the possibility that some of the intermediate cells may be of epithelial origin. By the 21st week, the overall appearance resembles that of the adult structure. This occurs 1week after the opening of the tunnel of Corti, and possibly marks the onset of cochlear function. 相似文献
185.
Humanherpesvirus 7(HHV 7)isoneofthemostrecentlydiscoveredmemberoftheher pesvirusfamily .Itwasfirstisolatedfromactivat edCD4 Tcellsfromperipheralbloodmononu clearcells (PBMCs)ofahealthyindividual[1] ,apatientwithchronicfatiguesyndrome(CFS) [2 ] ,andfromsalivaofheal… 相似文献
186.
本文用微吸管吸吮技术检测人疲劳运动前后中性粒细胞表面进入微吸管内的距离D(t)有明显差异。提示疲劳运动会降低人中性粒细胞的变形能力,影响其与变形有关的细胞吞噬功能。 相似文献
187.
Akitaka Yamasaki Kumiko Maruyama-Takahashi Kento Nishida Shogo Okazaki Kouki Okita Yasutoshi Akiyama Hideaki Suzuki Yuichi Endo Kazue Masuko Takashi Masuko Yoshihisa Tomioka 《Genes to cells : devoted to molecular & cellular mechanisms》2023,28(5):374-382
Human epidermal growth factor receptor (HER) family proteins are currently major targets of therapeutic monoclonal antibodies against various epithelial cancers. However, the resistance of cancer cells to HER family-targeted therapies, which may be caused by cancer heterogeneity and persistent HER phosphorylation, often reduces overall therapeutic effects. We herein showed that a newly discovered molecular complex between CD98 and HER2 affected HER function and cancer cell growth. The immunoprecipitation of the HER2 or HER3 protein from lysates of SKBR3 breast cancer (BrCa) cells revealed the HER2-CD98 or HER3-CD98 complex. The knockdown of CD98 by small interfering RNAs inhibited the phosphorylation of HER2 in SKBR3 cells. A bispecific antibody (BsAb) that recognized the HER2 and CD98 proteins was constructed from a humanized anti-HER2 (SER4) IgG and an anti-CD98 (HBJ127) single chain variable fragment, and this BsAb significantly inhibited the cell growth of SKBR3 cells. Prior to the inhibition of AKT phosphorylation, BsAb inhibited the phosphorylation of HER2, however, significant inhibition of HER2 phosphorylation was not observed in anti-HER2 pertuzumab, trastuzumab, SER4 or anti-CD98 HBJ127 in SKBR3 cells. The dual targeting of HER2 and CD98 has potential as a new therapeutic strategy for BrCa. 相似文献
188.
Moriya Hidetaka Maitani Yoshie Shimoda Naoto Takayama Kozo Nagai Tsuneji 《Pharmaceutical research》1997,14(11):1621-1628
Purpose. Recombinant human erythropoietin (Epo) is used frequently through intravenous (i.v.) and subcutaneous (s.c.) administration for the clinical treatment of the last stage of renal anemia. We encapsulated Epo in liposomes to develop an alternative administration route. The purpose of our study was to evaluate the pharmacokinetics and the pharmacological effects of liposomal Epo in comparison with the Epo after i.v. and s.c. administration to rats.
Methods. Epo was encapsulated in liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and soybean-derived sterol mixture (SS) prepared by the reversed-phase evaporation vesicle method. After filtration through a 0.1 m polycarbonate membrane, liposomes were gel filtered (Epo/liposomes).
Results. Epo/liposomes showed higher pharmacological activity than Epo/liposomes before gel filtration after i.v. administration to rats. Non-encapsulated Epo lost its activity, whereas encapsulated Epo in liposomes retained it. The pharmacological effects of Epo/liposomes were greater than those of Epo after i.v. administration. Epo/liposomes afforded 3–9 times higher AUC, lower clearance and lower steady-state volume of distribution than Epo after both i.v. and s.c. administrations. Epo/liposomes had an improved pharmacokinetic profile compared with Epo. S.c. administration of Epo/liposomes at 7 h may penetrate primarily (40% of dose) through the blood as a liposome and partly (7% of dose) in lymph.
Conclusions. Epo/liposomes may reduce the frequency of injections required for a certain reticulocyte effect in comparison to Epo. The lower clearance of Epo/liposomes may increase the plasma concentrations of Epo, which increases the efficacy. 相似文献
189.
Maria Svetlova Ljudmila Solovjeva Grigory Stein Claude Chamberland Baldev Vig Nikolai Tomilin 《Chromosome research》1994,2(1):47-52
Recentin situ hybridization studies suggested that within the range of 0.1–1.0 Mb, human interphase chromosomes follow a random walk model (i.e. they behave as flexible polymers without major constraints). However, chromosome structure may differ in the G1, S, and G2 phases, and phase-specific constraints may be masked if the chromosome analysis does not discriminate between the phases. Therefore, using confocal microscopy, we examined the structure of S-phase chromosomes labelled with 5-iododeoxyuridine after prolonged treatment with 5-fluorodeoxyuridine. In the S-phase, labelled 0.32 µ chromosome fibres mostly appear as semi-circles with an average diameter of 0.83 ±0.03 µ. These semi-circles are joined together to form different 3D structures, and two semicircles frequently adopt s- or-like conformations involving about 2.5 µ of the chromosome contour length (L). Morphometric analysis of the S-phase fibres suggests that our data fit both the random flexible polymer model and also a model in which two constrained semi-circles are attached to each other by a flexible joint, thus eliminating constraints at long distances (L more than 2 µ). 相似文献
190.
The Pittsburgh Sleep Diary 总被引:5,自引:3,他引:2
Monk TH Reynolds CF Kupfer DJ Buysse DJ Coble PA Hayes AJ MacHen MA Petrie SR Ritenour AM 《Journal of sleep research》1994,3(2):111-120
SUMMARY Increasingly, there is a need in both research and clinical practice to document and quantify sleep and waking behaviors in a comprehensive manner. The Pittsburgh Sleep Diary (PghSD) is an instrument with separate components to be completed at bedtime and waketime. Bedtime components relate to the events of the day preceding the sleep, waketime components to the sleep period just completed. Two-week PghSD data is presented from 234 different subjects, comprising 96 healthy young middle-aged controls, 37 older men, 44 older women, 29 young adult controls and 28 sleep disorders patients in order to demonstrate the usefulness, validity and reliability of various measures from the instrument. Comparisons are made with polysomnographic and actigraphic sleep measures, as well as personality and circadian type questionnaires. The instrument was shown to have sensitivity in detecting differences due to weekends, age, gender, personality and circadian type, and validity in agreeing with actigraphic estimates of sleep timing and quality. Over a 12–31 month delay, PghSD measures of both sleep timing and sleep quality showed correlations between 0.56 and 0.81 ( n = 39, P < 0.001). 相似文献