全文获取类型
收费全文 | 31859篇 |
免费 | 2901篇 |
国内免费 | 2418篇 |
专业分类
耳鼻咽喉 | 234篇 |
儿科学 | 259篇 |
妇产科学 | 331篇 |
基础医学 | 3753篇 |
口腔科学 | 490篇 |
临床医学 | 4706篇 |
内科学 | 4647篇 |
皮肤病学 | 249篇 |
神经病学 | 1713篇 |
特种医学 | 1062篇 |
外国民族医学 | 21篇 |
外科学 | 2904篇 |
综合类 | 5404篇 |
现状与发展 | 5篇 |
一般理论 | 2篇 |
预防医学 | 1820篇 |
眼科学 | 1192篇 |
药学 | 3603篇 |
26篇 | |
中国医学 | 1886篇 |
肿瘤学 | 2871篇 |
出版年
2024年 | 114篇 |
2023年 | 565篇 |
2022年 | 1475篇 |
2021年 | 1767篇 |
2020年 | 1354篇 |
2019年 | 1210篇 |
2018年 | 1115篇 |
2017年 | 1155篇 |
2016年 | 996篇 |
2015年 | 1584篇 |
2014年 | 1848篇 |
2013年 | 1521篇 |
2012年 | 2316篇 |
2011年 | 2533篇 |
2010年 | 1510篇 |
2009年 | 1178篇 |
2008年 | 1575篇 |
2007年 | 1574篇 |
2006年 | 1610篇 |
2005年 | 1818篇 |
2004年 | 993篇 |
2003年 | 854篇 |
2002年 | 779篇 |
2001年 | 676篇 |
2000年 | 651篇 |
1999年 | 762篇 |
1998年 | 537篇 |
1997年 | 503篇 |
1996年 | 397篇 |
1995年 | 369篇 |
1994年 | 308篇 |
1993年 | 219篇 |
1992年 | 236篇 |
1991年 | 213篇 |
1990年 | 193篇 |
1989年 | 147篇 |
1988年 | 149篇 |
1987年 | 106篇 |
1986年 | 101篇 |
1985年 | 66篇 |
1984年 | 29篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1977年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
应用抗增殖细胞核抗原和抑癌基因p53蛋白的单克隆抗体对37例放疗或化疗后的肺癌进行了检测,并与未经术前治疗的肺癌组织进行对照,部分组织进行了超微结构观察。结果发现:(1)放疗或化疗对肺癌组织细胞浆及胞核有不同程度的破坏。(2)放、化疗后组织(除分化型腺癌外)PCNA指数下降明显(P<0.01或P<0.05)。(3)放疗后肺癌组织p53表达率减低,但化疗后变化不明显。 相似文献
112.
Osteoblasts exhibit enhanced differentiation and altered gene profiles when cultured on hydroxyapatite (HA) compared to plastic surfaces. To begin determining mechanisms for this response, we used proteomics to identify proteins predominantly found in osteoblasts on HA but not plastic surfaces. Two-dimensional gel electrophoresis and Western analyses indicate that fetuin is abundant in extracts from HA, but not plastic surfaces. Incubation of HA and plastic surfaces with cell culture medium (containing 10% serum) under cell-free conditions shows that fetuin is predominantly derived from the culture medium serum and readily adsorbs to the HA surface. However, we did detect low levels of fetuin B mRNA in osteoblasts. Serum albumin, actin-beta, apolipoprotein-AI, and vimentin also adsorbed to HA. To determine the role of fetuin in the HA-induced osteoblast phenotype changes, osteoblasts were seeded onto fetuin-coated or uncoated HA under serum-free conditions. Osteoblast morphology was similar on both HA surfaces, suggesting that HA alone (without adsorbed serum proteins) is sufficient for cell attachment and spreading. Similarly, genes previously reported to be modulated by HA (glvr-1, DMP-1, osteoglycin, and proliferin 3) were modulated even in the absence of fetuin or other serum proteins. These data show that HA surface can be enriched selectively with fetuin from serum; however, neither fetuin or other serum proteins are required to mediate HA-induced osteoblast attachment, spreading, or changes in expression of genes examined. This finding suggests that factors intrinsic to HA are required for the response. 相似文献
113.
应用免疫组化等方法,对慢性迁延性丙型肝炎肝组织中呈结蛋白阳性的贮脂细胞进行了定量的研究结果;结蛋白阳性的细胞数量与同阶段的乙型肝炎相比显著减少;电镜观察可见肝窦中有较多的枯否细胞,肝细胞间隙及窦周胶原纤维的沉积。我们认为,在丙型肝炎早期纤维化中,贮脂细胞可能并非主要导致纤维化的效应细胞,这和乙型肝炎有所不同。 相似文献
114.
一种可生物降解温度敏感型聚乙二醇-聚己内酯-聚乙二醇水凝胶的合成和表征 总被引:1,自引:0,他引:1
合成了一系列分子量较低的聚乙二醇.聚己内酯-聚乙二醇(Poly(ethylene glycol)-Polycaprolactone-Poly(ethylene glycol),PEG-PCL—PEG)三嵌段共聚物。分别采用FTIR和1H—NMR对其结构进行了表征。所合成的PEG-PCL-PEG共聚物具有良好的水溶性,当水溶液浓度高于临界凝胶浓度(Critical gel concentration,CGC)时,随着温度的变化聚合物水溶液会呈现特有的凝胶-溶胶转变。研究了共聚物亲水疏水链段的比例和长度,以及热历史等对凝胶-溶胶转变行为的影响。通过调节上述条件,可以在一定程度上拓宽凝胶-溶胶转变温度范围,有助于PEG—PCL-PEG水凝胶在可注射药物控制释放系统等方面的应用。 相似文献
115.
本文报道用化学法全合成降钙素的基因。基因全长113碱基对。采用大肠杆菌偏爱密码子。整个基因分为6个片段合成。用T~4DNA连接酶一次连接成功,序列分析证明合成的基因序列与设计的一致。 相似文献
116.
Cultured Reed-Sternberg cells HDLM-1 and KM-H2 can be induced to become histiocytelike cells. H-RS cells are not derived from lymphocytes. 下载免费PDF全文
Two Hodgkin's Reed-Sternberg cell (H-RS) lines, HDLM-1 and KM-H2, have phenotypes and functional properties very similar to those of H-RS cells in tissues. These two types of cells were induced to differentiate with a combination of phorbol ester, retinoic acid, and extracellular matrix. The induced cells displayed the morphology of histiocytes or histiocytelike cells, with a small, round or oval, eccentric nucleus and abundant cytoplasm. In ultrastructural studies, many cytoplasmic projections and rugae were observed. These induced cells exhibited abundant cytoplasmic lysosomal enzymes, such as esterase, acid phosphatase, alpha 1-antitrypsin, or lysozyme. The histiocytic nature of these induced cells was further confirmed by the increased expression of many monocyte/histiocyte markers, including CD11b, CD11c, CD13, CD14, CD15, CD33, CD68, Mac387, and 1E9. In functional tests, the induced cells were shown to produce interleukin-1, tumor necrosis factor, macrophage colony-stimulating factor, and/or prostaglandin E2. Phagocytosis was detected in less than 5% to 10% of the cells when Candida albicans was added to cultures. The results strongly suggest that H-RS cells are related to cells of histiocyte lineage. 相似文献
117.
Effect of aging on neuroglobin expression in rodent brain 总被引:5,自引:0,他引:5
Sun Y Jin K Mao XO Xie L Peel A Childs JT Logvinova A Wang X Greenberg DA 《Neurobiology of aging》2005,26(2):275-278
Neuroglobin (Ngb), a recently discovered O2-binding heme protein related to hemoglobin and myoglobin, protects neurons from hypoxic-ischemic injury in vitro and in vivo. In immunostained mouse brain sections, we found widespread expression of Ngb protein in neurons, but not astrocytes, of several brain regions that are prominently involved in age-related neurodegenerative disorders. Western blots from young adult (3 month), middle-aged (12 month), and aged (24 month) rats showed an age-related decline in Ngb expression in cerebral neocortex, hippocampus, caudate-putamen, and cerebellum. Loss of this neuroprotective protein may have a role in increasing susceptibility to age-related neurological disorders. 相似文献
118.
Role of actin microfilament in osmotic stretch-induced increase of voltage-operated calcium channel current in guinea-pig gastric myocytes 总被引:5,自引:0,他引:5
Wen Xie Xu Sung Joon Kim Insuk So K. W. Kim 《Pflügers Archiv : European journal of physiology》1997,434(4):502-504
Using the whole-cell patch clamp technique, the role of actin microfilament in hyposmotic increase of voltage-operated calcium
channel current (I
Ba) was studied in guinea-pig gastric myocytes. Hyposmotic superfusate (212 mOsm) increased peak I
Ba amplitude by 32.7 ± 6.5%; when cytochalasin-D (Cyt-D, 20 μM), an actin cytoskeleton disruptor, was used, an increase of only
9.7 ± 3.1% was seen. I
Baresponse to osmotic stress was potentiated (45.1 ± 4.1% increase) by 20 μM phalloidin, an actin microfilament stabilizer.
However, colchicine (100 μM), an microtubule cytoskeleton disruptor, had no effect on either I
Ba or its response to hyposmotic solution. Phalloidin also induced a rightward shift of the I/V relationship of I
Ba, while Cyt-D itself had no effect. These results suggest that actin cytoskeleton may mediate hyposmotic stretch-induced I
Ba increase in gastric smooth muscle.
Received: 26 March 1997 / Received after revision: 28 May 1997 / Accepted: 3 June 1997 相似文献
119.
Silviu-Alin Bacanu Cynthia M Bulik Kelly L Klump Manfred M Fichter Katherine A Halmi Pamela Keel Allan S Kaplan James E Mitchell Alessandro Rotondo Michael Strober Janet Treasure D Blake Woodside Vibhor A Sonpar Weiting Xie Andrew W Bergen Wade H Berrettini Walter H Kaye Bernie Devlin 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2005,(1):61-68
To increase the likelihood of finding genetic variation conferring liability to eating disorders, we measured over 100 attributes thought to be related to liability to eating disorders on affected individuals from multiplex families and two cohorts: one recruited through a proband with anorexia nervosa (AN; AN cohort); the other recruited through a proband with bulimia nervosa (BN; BN cohort). By a multilayer decision process based on expert evaluation and statistical analysis, six traits were selected for linkage analysis (1): obsessionality (OBS), age at menarche (MENAR), and anxiety (ANX) for quantitative trait locus (QTL) linkage analysis; and lifetime minimum body mass index (BMI), concern over mistakes (CM), and food-related obsessions (OBF) for covariate-based linkage analysis. The BN cohort produced the largest linkage signals: for QTL linkage analysis, four suggestive signals: (for MENAR, at 10p13; for ANX, at 1q31.1, 4q35.2, and 8q13.1); for covariate-based linkage analyses, both significant and suggestive linkages (for BMI, one significant [4q21.1] and three suggestive [3p23, 10p13, 5p15.3]; for CM, two significant [16p13.3, 14q21.1] and three suggestive [4p15.33, 8q11.23, 10p11.21]; and for OBF, one significant [14q21.1] and five suggestive [4p16.1, 10p13.1, 8q11.23, 16p13.3, 18p11.31]). Results from the AN cohort were far less compelling: for QTL linkage analysis, two suggestive signals (for OBS at 6q21 and for ANX at 9p21.3); for covariate-based linkage analysis, five suggestive signals (for BMI at 4q13.1, for CM at 11p11.2 and 17q25.1, and for OBF at 17q25.1 and 15q26.2). Overlap between the two cohorts was minimal for substantial linkage signals. 相似文献
120.
运用敏感的B_9细胞增殖试验检测了81例多发性骨髓瘤(MM)患者血清IL-6活性,同时分析了标本的几种急性相蛋白含量,结果表明,68%MM患者血清中IL-6活性大于5μ/ml(正常对照为5μ/ml以下),几种急性相蛋白中C-反应性蛋白(CRP)在MM时升高(P<0.01),平均达正常对照组的17倍以上,MM患者补体C_4与正常对照组无差异(p>0.05),C_3、白蛋白及转铁蛋白在MM时分别比正常下降24.42%、38.83%和32.80%,且与疾病分期有关,在血清IL-6大于5μ/ml的55例中,IL-6活性与CRP、C_3、白蛋白的相关系数分别为0.46,-0.34和-0.29,IL-6与转铁蛋白浓度相关不明显。本文结果提示:CRP、C_3及白蛋白等含量的变化可作为反映MM病情的简易而敏感的指标。 相似文献