全文获取类型
收费全文 | 23663篇 |
免费 | 1291篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 218篇 |
儿科学 | 532篇 |
妇产科学 | 433篇 |
基础医学 | 3270篇 |
口腔科学 | 543篇 |
临床医学 | 2122篇 |
内科学 | 4495篇 |
皮肤病学 | 418篇 |
神经病学 | 2570篇 |
特种医学 | 926篇 |
外国民族医学 | 42篇 |
外科学 | 3272篇 |
综合类 | 289篇 |
一般理论 | 6篇 |
预防医学 | 1840篇 |
眼科学 | 677篇 |
药学 | 1627篇 |
1篇 | |
中国医学 | 22篇 |
肿瘤学 | 1709篇 |
出版年
2022年 | 177篇 |
2021年 | 337篇 |
2020年 | 216篇 |
2019年 | 328篇 |
2018年 | 396篇 |
2017年 | 308篇 |
2016年 | 330篇 |
2015年 | 465篇 |
2014年 | 610篇 |
2013年 | 934篇 |
2012年 | 1357篇 |
2011年 | 1410篇 |
2010年 | 762篇 |
2009年 | 712篇 |
2008年 | 1265篇 |
2007年 | 1403篇 |
2006年 | 1339篇 |
2005年 | 1364篇 |
2004年 | 1292篇 |
2003年 | 1209篇 |
2002年 | 1175篇 |
2001年 | 336篇 |
2000年 | 299篇 |
1999年 | 301篇 |
1998年 | 271篇 |
1997年 | 256篇 |
1996年 | 222篇 |
1995年 | 193篇 |
1994年 | 193篇 |
1993年 | 180篇 |
1992年 | 162篇 |
1991年 | 166篇 |
1990年 | 147篇 |
1989年 | 167篇 |
1988年 | 163篇 |
1987年 | 156篇 |
1986年 | 143篇 |
1985年 | 149篇 |
1984年 | 189篇 |
1983年 | 155篇 |
1982年 | 191篇 |
1981年 | 160篇 |
1980年 | 146篇 |
1979年 | 135篇 |
1978年 | 128篇 |
1977年 | 88篇 |
1976年 | 105篇 |
1975年 | 102篇 |
1974年 | 127篇 |
1973年 | 97篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
101.
102.
Bertrand Kimberly A. Rosner Bernard Eliassen A. Heather Hankinson Susan E. Rexrode Kathryn M. Willett Walter Tamimi Rulla M. 《Breast cancer research and treatment》2015,151(2):479-479
Breast Cancer Research and Treatment - Epidemiologic evidence for an association between plasma 25-hydroxyvitamin D [25(OH)D] and breast cancer is inconsistent. Data are especially limited for... 相似文献
103.
104.
Claudia Vollbrecht Robert Werner Robert Fred Henry Walter Daniel Christian Christoph Lukas Carl Heukamp Martin Peifer Burkhard Hirsch Lina Burbat Thomas Mairinger Kurt Werner Schmid Jeremias Wohlschlaeger Fabian Dominik Mairinger 《British journal of cancer》2015,113(12):1704-1711
Background:
Lung cancer is the leading cause of cancer-related deaths worldwide. The typical and atypical carcinoid (TC and AC), the large-cell neuroendocrine carcinoma (LCNEC) and the small-cell lung cancers (SCLC) are subgroups of pulmonary tumours that show neuroendocrine differentiations. With the rising impact of molecular pathology in routine diagnostics the interest for reliable biomarkers, which can help to differentiate these subgroups and may enable a more personalised treatment of patients, grows.Methods:
A collective of 70 formalin-fixed, paraffin-embedded (FFPE) pulmonary neuroendocrine tumours (17 TCs, 17 ACs, 19 LCNECs and 17 SCLCs) was used to identify biomarkers by high-throughput sequencing. Using the Illumina TruSeq Amplicon-Cancer Panel on the MiSeq instrument, the samples were screened for alterations in 221 mutation hot spots of 48 tumour-relevant genes.Results:
After filtering >26 000 detected variants by applying strict algorithms, a total of 130 mutations were found in 29 genes and 49 patients. Mutations in JAK3, NRAS, RB1 and VHL1 were exclusively found in SCLCs, whereas the FGFR2 mutation was detected in LCNEC only. KIT, PTEN, HNF1A and SMO were altered in ACs. The SMAD4 mutation corresponded to the TC subtype. We prove that the frequency of mutations increased with the malignancy of tumour type. Interestingly, four out of five ATM-mutated patients showed an additional alteration in TP53, which was by far the most frequently altered gene (28 out of 130; 22%). We found correlations between tumour type and IASLC grade for ATM- (P=0.022; P=0.008) and TP53-mutated patients (P<0.001). Both mutated genes were also associated with lymph node invasion and distant metastasis (P⩽0.005). Furthermore, PIK3CA-mutated patients with high-grade tumours showed a reduced overall survival (P=0.040) and the mutation frequency of APC and ATM in high-grade neuroendocrine lung cancer patients was associated with progression-free survival (PFS) (P=0.020).Conclusions:
The implementation of high-throughput sequencing for the analysis of the neuroendocrine lung tumours has revealed that, even if these tumours encompass several subtypes with varying clinical aggressiveness, they share a number of molecular features. An improved understanding of the biology of neuroendocrine tumours will offer the opportunity for novel approaches in clinical management, resulting in a better prognosis and prediction of therapeutic response. 相似文献105.
106.
107.
David Díaz-Carballo Ali Haydar Acikelli Jacqueline Klein Holger Jastrow Philipp Dammann Thomas Wyganowski Cihan Guemues Sebastian Gustmann Walter Bardenheuer Sascha Malak Nora Sophia Tefett Veria Khosrawipour Urs Giger-Pabst Andrea Tannapfel Dirk Strumberg 《Journal of experimental & clinical cancer research : CR》2015,34(1)
Background
Endoretroviruses account for circa 8 % of all transposable elements found in the genome of humans and other animals. They represent a genetic footprint of ancestral germ-cell infections of exoviruses that is transmittable to the progeny by Mendelian segregation. Traces of human endogenous retroviruses are physiologically expressed in ovarial, testicular and placental tissues as well as in stem cells. In addition, a number of these fossil viral elements have also been related to carcinogenesis. However, a relation between endoretroviruses expression and chemoresistance has not been reported yet.Methods
Twenty colorectal carcinoma patient samples were scrutinized for HERV-WE1 and HERV-FRD1 endoretroviruses using immunohistochemical approaches. In order to search for differential expression of these elements in chemotherapy refractory cells, a resistant HCT8 colon carcinoma subline was developed by serial etoposide exposure. Endoretroviral elements were detected by immunocytochemical staining, qPCR and ELISA. IC50-values of antiviral and cytostatic drugs in HCT8 cells were determined by MTT proliferation assay. The antivirals-cytostatics interaction was evaluated by the isobologram method.Results
In this work, we show for the first time that HERV-WE1, HERV-FRD1, HERV-31, and HERV-V1 are a) simultaneously expressed in treatment-naïve colon carcinoma cells and b) upregulated after cytostatic exposure, suggesting that these retroviral elements are intimately related to chemotherapy resistance. We found a number of antiviral drugs to have cytotoxic activity and the ability to force the downregulation of HERV proteins in vitro. We also demonstrate that the use of different antiviral compounds alone or in combination with anticancer agents results in a synergistic antiproliferative effect and downregulation of different endoretroviral elements in highly chemotherapy-resistant colorectal tumor cells.Conclusions
Enhanced HERV-expression is associated with chemoresistance in colon carcinomas which can be overcome by antiviral drugs alone or in combination with anticancer drugs. Therefore, the introduction of antiviral compounds to the current chemotherapy regimens potentially improves patient outcomes.Electronic supplementary material
The online version of this article (doi:10.1186/s13046-015-0199-5) contains supplementary material, which is available to authorized users. 相似文献108.
Chi Huu Nguyen Daniel Senfter Jose Basilio Silvio Holzner Serena Stadler Sigurd Krieger Nicole Huttary Daniela Milovanovic Katharina Viola Ingrid Simonitsch-Klupp Walter J?ger Rainer de Martin Georg Krupitza 《Oncotarget》2015,6(36):39262-39275
RELA, RELB, CREL, NFKB1 and NFKB2, and the upstream regulators NEMO and NIK were knocked-down in lymph endothelial cells (LECs) and in MDA-MB231 breast cancer spheroids to study the contribution of NF-κB in vascular barrier breaching. Suppression of RELA, NFKB1 and NEMO inhibited “circular chemo-repellent induced defects” (CCIDs), which form when cancer cells cross the lymphatic vasculature, by ~20–30%. Suppression of RELB, NFKB2 and NIK inhibited CCIDs by only ~10–15%. In MDA-MB231 cells RELA and NFKB1 constituted MMP1 expression, which caused the activation of PAR1 in adjacent LECs. The knock-down of MMP1 in MDA-MB231 spheroids and pharmacological inhibition of PAR1 in LECs inhibited CCID formation by ~30%. Intracellular Ca2+ release in LECs, which was induced by recombinant MMP1, was suppressed by the PAR1 inhibitor , thereby confirming a functional intercellular axis: RELA/NFKB1 – MMP1 (MDA-MB231) – PAR1 (LEC). Recombinant MMP1 induced PAR1-dependent phosphorylation of MLC2 and FAK in LECs, which is indicative for their activity and for directional cell migration such as observed during CCID formation. The combined knock-down of the NF-κB pathways in LECs and MDA-MB231 spheroids inhibited CCIDs significantly stronger than knock-down in either cell type alone. Also the knock-down of ICAM-1 in LECs (a NF-κB endpoint with relevance for CCID formation) and knock-down of MMP1 in MDA-MB231 augmented CCID inhibition. This evidences that in both cell types NF-κB significantly and independently contributes to tumour-mediated breaching of the lymphatic barrier. Hence, inflamed tumour tissue and/or vasculature pose an additional threat to cancer progression. SCH79797相似文献
109.
Paul E. Marik Walter T. Linde-Zwirble Edward A. Bittner Jennifer Sahatjian Douglas Hansell 《Intensive care medicine》2017,43(5):625-632
Purpose
The optimal strategy of fluid resuscitation in the early hours of severe sepsis and septic shock is controversial, with both an aggressive and conservative approach being recommended.Methods
We used the 2013 Premier Hospital Discharge database to analyse the administration of fluids on the first ICU day, in 23,513 patients with severe sepsis and septic shock, who were admitted to an ICU from the emergency department. Day 1 fluid was grouped into categories 1 L wide, starting with 1–1.99 L up to ≥9 L, to examine the effect of day 1 fluids on patient mortality. We built binary response models for hospital mortality and the propensity for receiving more than 5 L of fluids on day 1, using patient age and acute conditions present on admission. Patients were grouped by the requirement for mechanical ventilation and the presence or absence of shock. We assessed trends in the difference between actual and expected mortality, in the low fluid range (1–5 L day 1 fluids) and the high fluid range (5 to ≥9 L day 1 fluids) categories, using weighted linear regression controlling for the effects of sample size and variation within the day 1 fluid category.Results
Day 1 fluid administration averaged 4.4 L being lowest in the group with no mechanical ventilation and no shock (3.6 L) and highest (5.4 L) in the group receiving mechanical ventilation and in shock. The administration of day 1 fluids was remarkably consistent on the basis of hospital size, teaching status, rural/urban location, and region of the country. The hospital mortality in the entire cohort was 25.8%, with a mean ICU and hospital length of stay of 5.1 and 9.1 days, respectively. In the entire cohort, low volume resuscitation (1–4.99 L) was associated with a small but significant reduction in mortality, of ?0.7% per litre (95% CI ?1.0%, ?0.4%; p = 0.02). However, in patients receiving high volume resuscitation (5 to ≥9 L), the mortality increased by 2.3% (95% CI 2.0, 2.5%; p = 0.0003) for each additional litre above 5 L. Total hospital cost increased by $999 for each litre of fluid above 5 L (adjusted R 2 = 92.7%, p = 0.005).Conclusion
The mean amount of fluid administered to patients with severe sepsis and septic shock in the USA during the first ICU day is less than that recommended by the Surviving Sepsis Campaign guidelines. The administration of more than 5 L of fluid during the first ICU day is associated with a significantly increased risk of death and significantly higher hospital costs.110.
OBJECTIVE: The purpose of this study was to determine whether women with type 1 and type 2 diabetes are at higher risk of hip fractures. RESEARCH DESIGN AND METHODS: A total of 109,983 women aged 34-59 years in 1980 were followed through 2002 for the occurrence of hip fracture. At baseline and through biennial follow-up, women were asked about their history and treatment of diabetes and other potential risk factors for hip fracture. RESULTS: During 2.22 million person-years of follow-up, 1,398 women had a hip fracture. Compared with women without diabetes, the age-adjusted relative risk (RRs) of hip fracture was 7.1 (95% CI 4.4-11.4) for women with type 1 diabetes and 1.7 (1.4-2.0) for those with type 2 diabetes. After further adjustment for BMI, smoking, physical activity, menopausal status, daily intake of calcium, vitamin D, protein, and postmenopausal hormone use, the multivariate RR of incident hip fracture in individuals with type 1 diabetes compared with individuals without diabetes was 6.4 (3.9-10.3) and with type 2 diabetes was 2.2 (1.8-2.7). The RRs increased with longer duration of type 2 diabetes (3.1 [2.3-4.0] for >or=12 years compared with no diabetes, P for trend < 0.001) and ever use of insulin. CONCLUSIONS: These data indicate that both type 1 and type 2 diabetes are associated with an increased risk of hip fracture. The results of this study highlight the need for fracture-prevention strategies in women with diabetes. 相似文献