全文获取类型
收费全文 | 20691篇 |
免费 | 1316篇 |
国内免费 | 142篇 |
专业分类
耳鼻咽喉 | 159篇 |
儿科学 | 671篇 |
妇产科学 | 554篇 |
基础医学 | 2973篇 |
口腔科学 | 324篇 |
临床医学 | 1607篇 |
内科学 | 4900篇 |
皮肤病学 | 464篇 |
神经病学 | 2729篇 |
特种医学 | 700篇 |
外科学 | 2176篇 |
综合类 | 37篇 |
一般理论 | 1篇 |
预防医学 | 1177篇 |
眼科学 | 199篇 |
药学 | 1475篇 |
中国医学 | 38篇 |
肿瘤学 | 1965篇 |
出版年
2024年 | 35篇 |
2023年 | 235篇 |
2022年 | 469篇 |
2021年 | 824篇 |
2020年 | 468篇 |
2019年 | 579篇 |
2018年 | 853篇 |
2017年 | 623篇 |
2016年 | 701篇 |
2015年 | 779篇 |
2014年 | 930篇 |
2013年 | 1252篇 |
2012年 | 1671篇 |
2011年 | 1601篇 |
2010年 | 950篇 |
2009年 | 851篇 |
2008年 | 1374篇 |
2007年 | 1246篇 |
2006年 | 1121篇 |
2005年 | 1029篇 |
2004年 | 953篇 |
2003年 | 823篇 |
2002年 | 648篇 |
2001年 | 164篇 |
2000年 | 117篇 |
1999年 | 171篇 |
1998年 | 141篇 |
1997年 | 80篇 |
1996年 | 58篇 |
1995年 | 57篇 |
1994年 | 61篇 |
1993年 | 34篇 |
1992年 | 141篇 |
1991年 | 136篇 |
1990年 | 110篇 |
1989年 | 97篇 |
1988年 | 90篇 |
1987年 | 85篇 |
1986年 | 84篇 |
1985年 | 72篇 |
1984年 | 49篇 |
1983年 | 38篇 |
1982年 | 20篇 |
1980年 | 25篇 |
1979年 | 50篇 |
1978年 | 26篇 |
1976年 | 19篇 |
1973年 | 28篇 |
1969年 | 20篇 |
1967年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Loriano Ballarin Francesca Cima Armando Sabbadin 《Developmental and comparative immunology》1994,18(6):467-481
Phagocytosis by Botryllus schlosseri hemocytes in influenced by temperature, pH, concentration, and physicochemical properties of the test particles and requires Ca2+ or Mg2+ ions to occur. Phagocytes recognized glucosyl or mannosyl residues on the surface of yeast cells, and a respiratory burst is associated with phagocytosis, as indicated by increased superoxide production. Factors that enhance phagocytosis of yeast, sheep red blood cells, and latex beads and reduce the uptake of yeast and sheep erythrocytes are present in the plasma. 相似文献
72.
73.
Francesca Blasi Elena Bacchelli Giulia Pesaresi Simona Carone Anthony J Bailey Elena Maestrini 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2006,(3):220-221
Neuroligin abnormalities have been recently implicated in the aetiology of autism spectrum disorders (ASD), given the finding of point mutations in the two X-linked genes NLGN3 and NLGN4X and the important role of neuroligins in synaptogenesis. To enquire on the relevance and frequency of neuroligin mutations in ASD, we performed a mutation screening of NLGN3 and NLGN4X in a sample of 124 autism probands from the International Molecular Genetic Study of Autism Consortium (IMGSAC). We identified a new non-synonymous variant in NLGN3 (Thr632Ala), which is likely to be a rare polymorphism. Our data indicate that coding mutations in these genes are very rarely associated to ASD. 相似文献
74.
Ioachim HL Decuseara R Giancotti F Dorsett BH 《Pathology, research and practice》2005,200(11-12):743-751
FAS receptor (FAS, CD95) and FAS ligand (FAS-L, CD95-L) are complementary members of a particular apoptotic pathway that plays a major role in immune regulation. The activation of FAS-L may trigger cytotoxic mechanisms leading to the death of FAS-expressing cells. Tumor cells and tumor-infiltrating lymphocytes (TIL) may express FAS and FAS-L in various proportions, and their interplay may affect tumor behavior. In the present study, we explored the expression of FAS and FAS-L in 28 mammary carcinomas (19 ductal and 9 lobular) and in their lymph node metastases. The expression of these mediators in immunostained sections was graded and evaluated comparatively between normal and neoplastic mammary epithelium, between tumor cells and TILs, and between mammary carcinoma cells and their lymph node metastases. We demonstrated the coexpression of FAS and FAS-L by breast carcinoma cells and TIL, with FAS expressed more strongly by normal epithelial cells and TIL than tumor cells. FAS-L was better stained on tumor cells than on TIL. There was equal or greater expression of FAS and FAS-L in the primary tumors and their TIL than in the metastatic counterparts. Comparing the expression of FAS with that of FAS-L, we recorded FAS equal or stronger than FAS-L in the primary mammary tumors and the reversal of their expression, FAS-L greater than FAS in the lymph node metastases. These results are consistent with reports of studies with other tumors, suggesting that the upregulated FAS-L indicates an increased ability of tumor cells to induce apoptosis in TIL and in the normal tissues invaded. However, it is understood that the FAS/FAS-L system, although essential for apoptosis, is only a contributing factor to the complex process of tumor invasion and antitumor defense. 相似文献
75.
Belia S Pietrangelo T Fulle S Menchetti G Cecchini E Felaco M Vecchiet J Fanò G 《Journal of muscle research and cell motility》1998,19(8):865-876
Recently it has been hypothesized that, in skeletal muscle, NO produced directly by high-frequency stimulation could produce contraction through reactions with thiol groups on the sarcoplasmic reticulum (SR). However, a possible cGMP-mediated relaxing effect, similar to that seen in smooth muscle, has also been demonstrated. We used purified SR preparations and single fibres from frog fast muscles incubated with different concentrations of sodium nitroprusside (SNP) in this study. The results obtained from a long low-frequency stimulation, together with those from a study on Ca2+ transport regulation, showed that the presence of NO precursor induced: an acceleration of the onset of fatigue in single fibres; a decreased vesicular Ca2+ content due to increased Ca2+ release; a shift to open status in SR Ca2+ channels; an increase in SR Ca2+ pump activity. The data presented in this paper seem to indicate that the increased NO in the muscle fibres can influence muscle activity in different ways, perhaps depending on the metabolic status of the muscle and target (filaments, sarcolemma, SR) with which the NO (or its derivatives) acts. 相似文献
76.
77.
Genuardi M Carrara S Anti M Ponz de Leòn M Viel A 《European journal of human genetics : EJHG》1999,7(7):778-782
To determine the role played by MLH1 and MSH2 missense variants in cancer susceptibility, we have investigated the following genetic and biological characteristics associated with six MLH1 and four MSH2 missense changes identified in Italian hereditary nonpolyposis colorectal cancer (HNPCC) families: co-segregation with disease phenotype and/or bonafide pathogenetic mutations; presence of the variant in healthy control subjects; evolutionary conservation of the involved aminoacid and type of aminoacid change; and presence/absence of microsatellite instability (MSI) in tumour DNA. Overall, nine variants did not fulfil > or = 2 pathogenicity criteria. MSI was investigated in tumour samples from carriers of nine different missense mutations. Only 3/9 variants were associated with MSI in tumour DNA. In addition, four variants were not present in affected pedigree members, and five variants were observed in the control population. Based upon these results, we conclude that most MLH1 and MSH2 missense changes are unlikely to act as major causative factors in colorectal cancer susceptibility and development. 相似文献
78.
Ponzanelli Isabella; Landi Stefano; Bernacchi Francesca; Barale Roberto 《Mutagenesis》1997,12(5):329-333
We employed the three-way differential staining technique (TWD),which allows SCEs to be distinguished on a per generation basisby scoring third metaphases (M3), in order to study the spontaneouslevels of SCEs in normal and high frequency cells (HFCs) thatoccurred in the first (S1), second (S2) and third (S3) S phases.Fifty one of 900 lymphocytes from 37 healthy donors were definedas HFCs by calculating the 95th percentile of the distributionof SCEs in S1 + S2. Normal cells presented almostthe same number of SCEs after the first, second and third cellcycles (SCE averages of 2.43, 2.04 and 3.53 respectively). Incontrast, HFCs showed a higher SCE count in SI, which decreasedrapidly through the cycles and reached baseline level at S3(SCE averages of 7.18, 4.29 and 3.45 respectively). This wouldsuggest that the lesions responsible for the higher SCE frequencyin HFCs were effectively removed after two cell cycles and stronglysupport the hypothesis that HFCs are lymphocytes which accumulatehigher levels of DNA lesions through time.
1To whom correspondence should be addressed 相似文献
79.