全文获取类型
收费全文 | 38733篇 |
免费 | 2577篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 448篇 |
儿科学 | 1434篇 |
妇产科学 | 945篇 |
基础医学 | 4733篇 |
口腔科学 | 462篇 |
临床医学 | 6454篇 |
内科学 | 6725篇 |
皮肤病学 | 401篇 |
神经病学 | 3726篇 |
特种医学 | 799篇 |
外国民族医学 | 1篇 |
外科学 | 3575篇 |
综合类 | 362篇 |
一般理论 | 49篇 |
预防医学 | 5511篇 |
眼科学 | 409篇 |
药学 | 2362篇 |
中国医学 | 44篇 |
肿瘤学 | 2967篇 |
出版年
2024年 | 30篇 |
2023年 | 323篇 |
2022年 | 450篇 |
2021年 | 847篇 |
2020年 | 602篇 |
2019年 | 938篇 |
2018年 | 1092篇 |
2017年 | 812篇 |
2016年 | 851篇 |
2015年 | 945篇 |
2014年 | 1328篇 |
2013年 | 2093篇 |
2012年 | 3035篇 |
2011年 | 3213篇 |
2010年 | 1713篇 |
2009年 | 1551篇 |
2008年 | 2785篇 |
2007年 | 2792篇 |
2006年 | 2733篇 |
2005年 | 2685篇 |
2004年 | 2474篇 |
2003年 | 2196篇 |
2002年 | 2107篇 |
2001年 | 240篇 |
2000年 | 206篇 |
1999年 | 275篇 |
1998年 | 434篇 |
1997年 | 337篇 |
1996年 | 260篇 |
1995年 | 209篇 |
1994年 | 216篇 |
1993年 | 208篇 |
1992年 | 128篇 |
1991年 | 115篇 |
1990年 | 92篇 |
1989年 | 99篇 |
1988年 | 90篇 |
1987年 | 79篇 |
1986年 | 83篇 |
1985年 | 82篇 |
1984年 | 99篇 |
1983年 | 76篇 |
1982年 | 90篇 |
1981年 | 99篇 |
1980年 | 70篇 |
1979年 | 41篇 |
1978年 | 31篇 |
1977年 | 38篇 |
1976年 | 21篇 |
1975年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Daniel D. Billadeau Subrha Chatterjee Patricia Bramati Raghavakaimal Sreekumar Vijay Shah Karen Hedin Raul Urrutia 《Journal of gastrointestinal cancer》2006,37(4):110-119
CXCL12 and its receptor, CXCR4, are emerging as promising targets for modulating growth, angiogenesis, and metastasis in several human cancers. Indeed, blocking the receptor is sufficient to prevent metastasis and angiogenesis in experimental breast cancer xenografts. Recently, the biological effect of the CXCR4 in pancreatic cancer, one of the most deadly neoplastic diseases, has been reported. However, the molecular mechanism by which CXCR4 contributes to these properties is not completely understood. In this paper, we characterize the signaling pathways activated by CXCR4 in pancreatic cancer. We show that after CXCR4 activation, EGFR becomes tyrosine phosphorylated, and the kinase activity of this receptor, together with the activation of MMPs, Src, and PI3-Kinase, is required for CXCR4-mediated ERK activation. Analysis of this cascade in pancreatic cancer cells revealed that the ERK-mediated pathway regulates genes involved in angiogenesis, such as VEGF, CD44, HIF1α, and IL-8. Furthermore, ERK blockage inhibits the migration and tube formation of endothelial cells induced by CXCL12. Considering that inhibitors for several components of this pathway, including CXCR4 itself, are at different stages of clinical trials, this study provides theoretical justification for the clinical testing of these drugs in pancreatic cancer, thus extending the list of potential targets for treating this dismal disease. 相似文献
22.
Frank A Middleton Marco G Trauzzi Antony E Shrimpton Karen L Gentile Christopher P Morley Helena Medeiros Michele T Pato Carlos N Pato 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2006,(1):28-32
Uniparental isodisomy (iUPD) is a rare genetic condition caused by non-disjunction during meiosis that ultimately leads to a duplication of either the maternal or paternal chromosome in the affected individual. Two types of disorders can result, those due to imprinted genes and those due to homozygosity of recessive disease-causing mutations. Here, we describe the third known case of complete chromosome 4 iUPD of maternal origin. This condition became apparent during whole genome linkage studies of psychiatric disorders in the Portuguese population. The proband is an adult female with normal fertility and no major medical complaints, but a history of major depressive disorder and multiple suicide attempts. The proband's siblings and parents had normal chromosome 4 genotypes and no history of mood disturbance. A brief review of other studies lends support for the possibility that genes on chromosome 4 might confer risk for mood disorders. We conclude that chromosome 4 maternal uniparental disomy (UPD) is a rare disorder that may present with a major depressive phenotype. The lack of a common disease phenotype between this and two other cases of chromosome 4 iUPD [Lindenbaum et al. [1991] Am J Med Genet 49(Suppl 285):1582; Spena et al. [2004] Eur J Hum Genet 12:891-898) would suggest that there is no vital maternal gene imprinting on chromosome 4. However, since there is no reported case of paternal chromosome 4 UPD, paternal gene imprinting on chromosome 4 cannot be excluded. 相似文献
23.
Comparison of ThinPrep versus conventional smear cytopreparatory techniques for fine-needle aspiration specimens of head and neck masses. 总被引:2,自引:0,他引:2
Lloyd Ford Barry M Rasgon Raymond L Hilsinger Raul M Cruz Karen Axelsson Gregory J Rumore Thomas M Schmidtknecht Balaram Puligandla John Sawicki William Pshea 《Otolaryngology--head and neck surgery》2002,126(5):554-561
OBJECTIVES: Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses. METHODS: In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques. RESULTS: ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses. CONCLUSIONS: For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe. 相似文献
24.
Jenny Chang-Claude Silke Hermann Ursula Eilber Karen Steindorf 《Cancer epidemiology, biomarkers & prevention》2005,14(4):963-968
BACKGROUND: The long-term observation of vegetarians in affluent countries can provide insight into the relative effects of a vegetarian diet and lifestyle factors on mortality. METHODS: A cohort study of vegetarians and health-conscious persons in Germany was followed-up prospectively for 21 years, including 1,225 vegetarians and 679 health-conscious nonvegetarians. Standardized mortality ratios compared with the German general population were calculated for all causes and specific causes. Within the cohort, Poisson regression modeling was used to investigate the joint effects of several risk factors on overall and cause-specific mortality. RESULTS: Standardized mortality ratios for all-cause mortality was significantly below 100: 59 [95% confidence interval (95% CI), 54-64], predominantly due to a deficit of deaths from circulatory diseases. Within the cohort, vegetarian compared with nonvegetarian diet had no effect on overall mortality [rate ratio (RR), 1.10; 95% CI, 0.89-1.36], whereas moderate and high physical activity significantly reduced risk of death (RR, 0.62, 0.64), adjusted for age, sex, smoking, alcohol intake, body mass index, and educational level. Vegetarian diet was however associated with a reduced RR of 0.70 (95% CI, 0.41-1.18) for ischemic heart disease, which could partly be related to avoidance of meat. CONCLUSIONS: Both vegetarians and nonvegetarian health-conscious persons in this study have reduced mortality compared with the general population. Within the study, low prevalence of smoking and moderate or high level of physical activity but not strictly vegetarian diet was associated with reduced overall mortality. The nonsignificant reduction in mortality from ischemic heart diseases in vegetarians compared with health-conscious persons could be explained in part by avoidance of meat intake. 相似文献
25.
26.
27.
28.
A convenience sample of hospital workers, those receiving influenza vaccine and those not receiving vaccine, were asked to complete questionnaires delineating the occurrence of symptoms (e.g., fever, headache, extreme tiredness, dry cough, sore throat, runny nose, stuffy nose, muscle aches) and absenteeism in the 7-day period post-vaccination if vaccinated. Those unvaccinated completed the questionnaire in a self-selected 7 consecutive day period during the study conducted from November 2004 to February 2005. Those receiving either Fluzone or FluMist reported significantly fewer symptoms and related absenteeism than the unvaccinated group (p < .05). Administration of influenza vaccine did not result in higher rates of post-vaccination symptoms as compared to an unvaccinated group. Further, vaccinated employees did not experience higher absenteeism rates as a result of receiving either influenza vaccine. However, for those reporting absenteeism as a result of symptoms, mean absenteeism days were highest in the FluMist group (4.5 days) compared to the unvaccinated group (2.1 days) and the Fluzone group (1.9 days). 相似文献
29.
30.