全文获取类型
收费全文 | 3411篇 |
免费 | 148篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 185篇 |
妇产科学 | 40篇 |
基础医学 | 268篇 |
口腔科学 | 59篇 |
临床医学 | 245篇 |
内科学 | 817篇 |
皮肤病学 | 79篇 |
神经病学 | 204篇 |
特种医学 | 123篇 |
外科学 | 614篇 |
综合类 | 45篇 |
一般理论 | 3篇 |
预防医学 | 136篇 |
眼科学 | 192篇 |
药学 | 182篇 |
中国医学 | 4篇 |
肿瘤学 | 333篇 |
出版年
2024年 | 3篇 |
2023年 | 25篇 |
2022年 | 46篇 |
2021年 | 136篇 |
2020年 | 59篇 |
2019年 | 83篇 |
2018年 | 98篇 |
2017年 | 74篇 |
2016年 | 80篇 |
2015年 | 106篇 |
2014年 | 138篇 |
2013年 | 180篇 |
2012年 | 249篇 |
2011年 | 260篇 |
2010年 | 176篇 |
2009年 | 121篇 |
2008年 | 219篇 |
2007年 | 242篇 |
2006年 | 234篇 |
2005年 | 227篇 |
2004年 | 191篇 |
2003年 | 160篇 |
2002年 | 143篇 |
2001年 | 27篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 34篇 |
1997年 | 27篇 |
1996年 | 26篇 |
1995年 | 20篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1972年 | 5篇 |
1971年 | 9篇 |
排序方式: 共有3571条查询结果,搜索用时 15 毫秒
91.
92.
Three patients with metastatic breast cancer responded to diethylstilbestrol (DES) therapy, but later they developed endometrial carcinoma. Evidence is presented to support the hypothesis that endometrial carcinoma can occur in breast cancer patients receiving diethylstilbestrol therapy. 相似文献
93.
Elaine C. Khoong Natalie A. Rivadeneira Lucia Pacca Dean Schillinger David Lown Palav Babaria Neha Gupta Rajiv Pramanik Helen Tran Tyler Whitezell Ma Somsouk Urmimala Sarkar 《Journal of general internal medicine》2023,38(1):21
BackgroundInequitable follow-up of abnormal cancer screening tests may contribute to racial/ethnic disparities in colon and breast cancer outcomes. However, few multi-site studies have examined follow-up of abnormal cancer screening tests and it is unknown if racial/ethnic disparities exist.ObjectiveThis report describes patterns of performance on follow-up of abnormal colon and breast cancer screening tests and explores the extent to which racial/ethnic disparities exist in public hospital systems.DesignWe conducted a retrospective cohort study using data from five California public hospital systems. We used multivariable robust Poisson regression analyses to examine whether patient-level factors or site predicted receipt of follow-up test.Main MeasuresUsing data from five public hospital systems between July 2015 and June 2017, we assessed follow-up of two screening results: (1) colonoscopy after positive fecal immunochemical tests (FIT) and (2) tissue biopsy within 21 days after a BIRADS 4/5 mammogram.Key ResultsOf 4132 abnormal FITs, 1736 (42%) received a follow-up colonoscopy. Older age, Medicaid insurance, lack of insurance, English language, and site were negatively associated with follow-up colonoscopy, while Hispanic ethnicity and Asian race were positively associated with follow-up colonoscopy. Of 1702 BIRADS 4/5 mammograms, 1082 (64%) received a timely biopsy; only site was associated with timely follow-up biopsy.ConclusionDespite the vulnerabilities of public-hospital-system patients, follow-up of abnormal cancer screening tests occurs at rates similar to that of patients in other healthcare settings, with colon cancer screening test follow-up occurring at lower rates than follow-up of breast cancer screening tests. Site-level factors have larger, more consistent impact on follow-up rates than patient sociodemographic traits. Resources are needed to identify health system–level factors, such as test follow-up processes or data infrastructure, that improve abnormal cancer screening test follow-up so that effective health system–level interventions can be evaluated and disseminated.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-022-07657-4.KEY WORDS: safety-net system, cancer screening, colon cancer, breast cancer, cancer disparities 相似文献
94.
Doe C Bentley R Behm DJ Lafferty R Stavenger R Jung D Bamford M Panchal T Grygielko E Wright LL Smith GK Chen Z Webb C Khandekar S Yi T Kirkpatrick R Dul E Jolivette L Marino JP Willette R Lee D Hu E 《The Journal of pharmacology and experimental therapeutics》2007,320(1):89-98
Increased Rho kinase (ROCK) activity contributes to smooth muscle contraction and regulates blood pressure homeostasis. We hypothesized that potent and selective ROCK inhibitors with novel structural motifs would help elucidate the functional role of ROCK and further explore the therapeutic potential of ROCK inhibition for hypertension. In this article, we characterized two aminofurazan-based inhibitors, GSK269962A [N-(3-{[2-(4-amino-1,2,5-oxadiazol-3-yl)-1-ethyl-1H-imidazo[4, 5-c]pyridin-6-yl]oxy}phenyl)-4-{[2-(4-morpholinyl)ethyl]-oxy}benzamide] and SB-7720770-B [4-(7-{[(3S)-3-amino-1-pyrrolidinyl]carbonyl}-1-ethyl-1H-imidazo[4,5-c]pyridin-2-yl)-1,2,5-oxadiazol-3-amine], as members of a novel class of compounds that potently inhibit ROCK enzymatic activity. GSK269962A and SB-772077-B have IC50 values of 1.6 and 5.6 nM toward recombinant human ROCK1, respectively. GSK269962A also exhibited more than 30-fold selectivity against a panel of serine/threonine kinases. In lipopolysaccharide-stimulated monocytes, these inhibitors blocked the generation of inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha. Furthermore, both SB-772077-B and GSK269962A induced vasorelaxation in preconstricted rat aorta with an IC50 of 39 and 35 nM, respectively. Oral administration of either GSK269962A or SB-772077-B produced a profound dose-dependent reduction of systemic blood pressure in spontaneously hypertensive rats. At doses of 1, 3, and 30 mg/kg, both compounds induced a reduction in blood pressure of approximately 10, 20, and 50 mm Hg. In addition, administration of SB-772077-B also dramatically lowered blood pressure in DOCA salt-induced hypertensive rats. SB-772077-B and GSK269962A represent a novel class of ROCK inhibitors that have profound effects in the vasculature and may enable us to further evaluate the potential beneficial effects of ROCK inhibition in animal models of cardiovascular as well as other chronic diseases. 相似文献
95.
96.
97.
Sitara Swarna Rao Ajjampur Farzana Begum Liakath Arun Kannan Priya Rajendran Rajiv Sarkar Prabhakar Devarajan Moses Anna Simon Indira Agarwal Ann Mathew Roberta O'Connor Honorine Ward Gagandeep Kang 《Journal of clinical microbiology》2010,48(6):2075-2081
Cryptosporidium spp., a common cause of diarrhea in children, were investigated in the first multisite study in India. Diarrheal stools from hospitalized children aged <5 years from Delhi, Trichy, and Vellore were analyzed by microscopy, PCR-restriction fragment length polymorphism (RFLP), and/or sequencing at the small-subunit (SSU) rRNA and Cpgp40/15 loci for species determination and subgenotyping, respectively. Seventy of 2,579 (2.7%) children, 75% of whom were <2 years old, had cryptosporidial diarrhea as determined by microscopy. Genotyping and subgenotyping showed that Cryptosporidium hominis was the most commonly identified species (59/67 children), and subgenotypes Ie, Ia, Ib, and Id were common in all centers. A novel C. parvum subgenotype, IIn, was identified in Vellore. Meteorological analysis revealed a higher rate of cryptosporidial positivity during hotter and drier weather in Delhi.Cryptosporidium spp. are an important cause of endemic parasitic diarrhea in children in developing countries. In addition to causing symptoms associated with watery diarrhea, vomiting, and weight loss, early childhood cryptosporidiosis has been shown by studies to be associated with subsequent faltering of growth (reviewed in reference 11). Cryptosporidium hominis and C. parvum cause the majority of infections in children in developing countries, with C. hominis predominating and occasional reports of infection with zoonotic species such as C. felis, C. canis, C. meleagridis, and C. muris (30). C. hominis infection has been found to be associated with greater levels of oocyst shedding (4) and longer durations of oocyst shedding (31) and diarrhea (15) than C. parvum infection. In a recent community-based study in Vellore, we found increased levels of severity of diarrhea in C. hominis-infected children compared to the levels observed in children infected with other species (1).Cryptosporidium spp. have been classified into several distinct subgenotypes based on extensive polymorphisms in the Cpgp40/15 (also referred to as GP60) locus by use of PCR-restriction fragment length polymorphism (RFLP) or sequencing of PCR products (reviewed in reference 30).A number of studies from India have reported Cryptosporidium spp. in diarrheal stool samples from children, with positivity rates of up to nearly 20% (17) and asymptomatic infection rates of up to 10% (19), using stool microscopy for detection. However, only three studies have used molecular techniques for identification of cryptosporidiosis in children in India (9, 13, 22), suggesting that the actual infection rates may be significantly higher. In a previous hospital-based study in Vellore, we that found that PCR (15.2%) identified more than 3 times the number of cases of cryptosporidial diarrhea than microscopy (4.4%) (2). The aim of the present study was to identify the Cryptosporidium species and Cpgp40/15 subgenotypes associated with cryptosporidial diarrhea in hospitalized children from 3 centers in the country, since no studies have examined cryptosporidiosis using the same methods in more than one location. 相似文献
98.
Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans 总被引:5,自引:0,他引:5 下载免费PDF全文
Linn SC West RB Pollack JR Zhu S Hernandez-Boussard T Nielsen TO Rubin BP Patel R Goldblum JR Siegmund D Botstein D Brown PO Gilks CB van de Rijn M 《The American journal of pathology》2003,163(6):2383-2395
Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes. 相似文献
99.
Andreas Gast Dominique Scherer Bowang Chen Sandra Bloethner Stephanie Melchert Antje Sucker Kari Hemminki Dirk Schadendorf Rajiv Kumar 《Genes, chromosomes & cancer》2010,49(8):733-745
We performed DNA microarray‐based comparative genomic hybridization to identify somatic alterations specific to melanoma genome in 60 human cell lines from metastasized melanoma and from 44 corresponding peripheral blood mononuclear cells. Our data showed gross but nonrandom somatic changes specific to the tumor genome. Although the CDKN2A (78%) and PTEN (70%) loci were the major targets of mono‐allelic and bi‐allelic deletions, amplifications affected loci with BRAF (53%) and NRAS (12%) as well as EGFR (52%), MITF (40%), NOTCH2 (35%), CCND1 (18%), MDM2 (18%), CCNE1 (10%), and CDK4 (8%). The amplified loci carried additional genes, many of which could potentially play a role in melanoma. Distinct patterns of copy number changes showed that alterations in CDKN2A tended to be more clustered in cell lines with mutations in the BRAF and NRAS genes; the PTEN locus was targeted mainly in conjunction with BRAF mutations. Amplification of CCND1, CDK4, and other loci was significantly increased in cell lines without BRAF‐NRAS mutations and so was the loss of chromosome arms 13q and 16q. Our data suggest involvement of distinct genetic pathways that are driven either through oncogenic BRAF and NRAS mutations complemented by aberrations in the CDKN2A and PTEN genes or involve amplification of oncogenic genomic loci and loss of 13q and 16q. It also emerges that each tumor besides being affected by major and most common somatic genetic alterations also acquires additional genetic alterations that could be crucial in determining response to small molecular inhibitors that are being currently pursued. © 2010 Wiley‐Liss, Inc. 相似文献
100.
Mohammad Asim Abdul Malik Manash P. Sarma Sunil K. Polipalli Nargis Begum Istaq Ahmad Luqman A. Khan S.A. Husain Naseem Akhtar Sajid Husain L. Thayumanavan Rajiv Singla P. Kar 《Journal of medical virology》2010,82(7):1115-1125
The study aims to characterize mutations of the HBV genome involving BCP, Precore/core and X regions and also defines HBV genotypes in patients of hepatocellular carcinoma (HCC). The study involved 150 HBV‐related HCC cases and 136 HBV‐related chronic liver disease patients without HCC as controls. HBV DNA was subjected to mutational analysis using SSCP technique, genotyping by RFLP, and direct nucleotide sequencing. HBV DNA was found in 58.7% (88/150) of the HCC cases and 74.3% (101/136) of controls. HBV mutants were observed in 44.3% of HCC cases and 43.2% of controls. HBV/D was prevalent amongst the patients and controls, followed by HBV/A. The prevalence of the TT1504 mutation in the X gene, the V1753 and T1762/A1764 mutations in the BCP region, and G1914 mutation in the core gene were significantly higher in the HCC group than in the non‐HCC group. Multivariate analyses showed that the TT1504, V1753, A1762T/G1764A, and the G1914 mutations and the patient's age, sex, and HBeAg status increased the risk of HCC development significantly. Also, patients with HCC had lower levels of serum albumin, viral load, and platelet counts but higher values of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, and Alpha feto‐protein than those of controls (P < 0.001 for all comparisons). HBV/D was the predominant genotype associated with HCC cases seen in India. The presence of different types of HBV mutations, age, sex, HBeAg status, and viral load was found to increase significantly the risk of HCC development in India. J. Med. Virol. 82: 1115–1125, 2010. © 2010 Wiley‐Liss, Inc. 相似文献