全文获取类型
收费全文 | 858篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 38篇 |
妇产科学 | 4篇 |
基础医学 | 146篇 |
口腔科学 | 77篇 |
临床医学 | 50篇 |
内科学 | 126篇 |
皮肤病学 | 10篇 |
神经病学 | 54篇 |
特种医学 | 11篇 |
外科学 | 127篇 |
综合类 | 24篇 |
一般理论 | 1篇 |
预防医学 | 62篇 |
眼科学 | 37篇 |
药学 | 87篇 |
中国医学 | 6篇 |
肿瘤学 | 31篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 21篇 |
2021年 | 37篇 |
2020年 | 12篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 19篇 |
2016年 | 25篇 |
2015年 | 30篇 |
2014年 | 41篇 |
2013年 | 45篇 |
2012年 | 80篇 |
2011年 | 66篇 |
2010年 | 37篇 |
2009年 | 27篇 |
2008年 | 61篇 |
2007年 | 47篇 |
2006年 | 50篇 |
2005年 | 36篇 |
2004年 | 42篇 |
2003年 | 30篇 |
2002年 | 28篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
1.
Norethisterone enanthate (NET-En), an established intramuscular long-acting contraceptive agent, has previously been shown to be effective in inhibiting fertility in two rodent species even 4 days after oral ingestion. Pharmacokinetics of NET and NET-En were studied after oral and intramuscular doses in two animal species and a few women. The results suggest that the NET-En was absorbed within a day in all the species after oral dose. The estimates of relative bioavailability ranged from 13 to 51% in rabbits, monkeys, and women. The elimination half-life was 5–10 days. The presence of the active component, NET, in the circulation over the experimental period of 15 days suggests that NET-En could be useful as a long-acting oral pill. The suppression of progesterone levels during the luteal phase of menstrual cycle in women also supports this finding. 相似文献
2.
Kalai Arasu Muthusamy Vicknes Waran Savithri D. Puthucheary 《Journal of clinical neuroscience》2007,14(12):1213-1215
Burkholderia pseudomallei infection of the central nervous system (CNS) is rare with less than 50 cases reported over the last 30 years. The retrospective melioidosis study at University Malaya Medical Centre has documented three cases of CNS melioidosis out of more than 160 cases of melioidosis since 1978. There were two patients with brain abscess and one with spinal epidural abscess. The predisposing factors were: one patient was an aboriginal farmer and the other two were diabetic. Their age ranged from 17 to 45 years. Prominent neurological features were limb weakness, cranial nerve palsy (6th and 7th) and visual disturbance. CT brain scan and MRI spine showed abscess formation, subdural collection, and spinal epidural collection, osteomyelitis of vertebra and occipital bone and also sagital sinus thrombosis. All these patients underwent surgical drainage leading to bacteriological diagnosis as well as appropriate long-term antibiotic therapy. All had good recovery at 6 months after completion of treatment. 相似文献
3.
Backscatter imaging is useful for inspecting structures that are accessible only from one side. However, indications provided by scattered radiation are typically weak, convoluted and difficult to interpret. This paper explores the use of the coded aperture technique to detect flaws using gamma-ray backscatter imaging. The viability of this approach is demonstrated with indications obtained from Monte Carlo simulations of radiation scattering measurements. The results show that, with a 2 mm wide beam of 137Cs photons, flaws as small as 1.5 mm in width can be detected using this technique. Indications of changes in flaw size, location, multiplicity and density were also observable. In addition, it is possible to quantify, from the decoded indications, the flaw location and its size. 相似文献
4.
Pattern of Sequence Variation Across 213 Environmental Response Genes 总被引:10,自引:0,他引:10
Robert J. Livingston Andrew von Niederhausern Anil G. Jegga Dana C. Crawford Christopher S. Carlson Mark J. Rieder Sivakumar Gowrisankar Bruce J. Aronow Robert B. Weiss Deborah A. Nickerson 《Genome research》2004,14(10A):1821-1831
To promote the clinical and epidemiological studies that improve our understanding of human genetic susceptibility to environmental exposure, the Environmental Genome Project (EGP) has scanned 213 environmental response genes involved in DNA repair, cell cycle regulation, apoptosis, and metabolism for single nucleotide polymorphisms (SNPs). Many of these genes have been implicated by loss-of-function mutations associated with severe diseases attributable to decreased protection of genomic integrity. Therefore, the hypothesis for these studies is that individuals with functionally significant polymorphisms within these genes may be particularly susceptible to genotoxic environmental agents. On average, 20.4 kb of baseline genomic sequence or 86% of each gene, including a substantial amount of introns, all exons, and 1.3 kb upstream and downstream, were scanned for variations in the 90 samples of the Polymorphism Discovery Resource panel. The average nucleotide diversity across the 4.2 MB of these 213 genes is 6.7 × 10-4, or one SNP every 1500 bp, when two random chromosomes are compared. The average candidate environmental response gene contains 26 PHASE inferred haplotypes, 34 common SNPs, 6.2 coding SNPs (cSNPs), and 2.5 nonsynonymous cSNPs. SIFT and Polyphen analysis of 541 nonsynonymous cSNPs identified 57 potentially deleterious SNPs. An additional eight polymorphisms predict altered protein translation. Because these genes represent 1% of all known human genes, extrapolation from these data predicts the total genomic set of cSNPs, nonsynonymous cSNPs, and potentially deleterious nonsynonymous cSNPs. The implications for the use of these data in direct and indirect association studies of environmentally induced diseases are discussed. 相似文献
5.
Udayachander M Meenakshi A Sivakumar N Kumar RR Shankar SG Dean CJ Modjtahedi H 《Human antibodies》1999,9(3):149-154
Monoclonal antibody CIBCNSH3 of IgG1 isotype has been generated against human epidermal growth factor receptor (EGFR) using MDA MB 468 breast carcinoma cell line as immunogen. Earlier studies have revealed that this MAb blocked growth factor-receptor interaction and thus inhibited cell proliferation and tumor growth. In the present paper, this MAb has been extensively characterized to evaluate its application in the study of human cancers. The results were compared with those obtained using a control MAb ICR 62 specific to EGFR. Competitive assay showed that this MAb bound to an epitope in the extracellular domain of the EGFR to which MAb ICR 62 also bound. This MAb immunoprecipitated the 170 kD glycoprotein. The specificity was further confirmed by the formation of a single discrete band in western blot analysis. By flow cytometric analysis this monoclonal antibody revealed high binding affinity with MDA MB 468 cells. By immunocytochemical assay, out of 35 breast tumors studied, 40% were found to exhibit strong cell membrane staining and in the case of 25 oral cancers studied, 56% were strong positive. High expression of EGFR was observed in MDA MB 468 cells and HN 5 cells. These studies clearly indicate that MAb CIBCNSH3 might prove useful to identify tumors with high level of expression of EGFR associated with poor prognosis. 相似文献
6.
Tyrer P Thompson S Schmidt U Jones V Knapp M Davidson K Catalan J Airlie J Baxter S Byford S Byrne G Cameron S Caplan R Cooper S Ferguson B Freeman C Frost S Godley J Greenshields J Henderson J Holden N Keech P Kim L Logan K Manley C MacLeod A Murphy R Patience L Ramsay L De Munroz S Scott J Seivewright H Sivakumar K Tata P Thornton S Ukoumunne OC Wessely S 《Psychological medicine》2003,33(6):969-976
BACKGROUND: We carried out a large randomized trial of a brief form of cognitive therapy, manual-assisted cognitive behaviour therapy (MACT) versus treatment as usual (TAU) for deliberate self-harm. METHOD: Patients presenting with recurrent deliberate self-harm in five centres were randomized to either MACT or (TAU) and followed up over 1 year. MACT patients received a booklet based on cognitive behaviour therapy (CBT) principles and were offered up to five plus two booster sessions of CBT from a therapist in the first 3 months of the study. Ratings of parasuicide risk, anxiety, depression, social functioning and global function, positive and negative thinking, and quality of life were measured at baseline and after 6 and 12 months. RESULTS: Four hundred and eighty patients were randomized. Sixty per cent of the MACT group had both the booklet and CBT sessions. There were seven suicides, five in the TAU group. The main outcome measure, the proportion of those repeating deliberate self-harm in the 12 months of the study, showed no significant difference between those treated with MACT (39%) and treatment as usual (46%) (OR 0.78, 95% CI 0.53 to 1.14, P=0.20). CONCLUSION: Brief cognitive behaviour therapy is of limited efficacy in reducing self-harm repetition, but the findings taken in conjunctin with the economic evaluation (Byford et al. 2003) indicate superiority of MACT over TAU in terms of cost and effectiveness combined. 相似文献
7.
Genetic variability of begomoviruses associated with cotton leaf curl disease originating from India 总被引:4,自引:1,他引:4
Kirthi N Priyadarshini CG Sharma P Maiya SP Hemalatha V Sivaraman P Dhawan P Rishi N Savithri HS 《Archives of virology》2004,149(10):2047-2057
Summary. Cotton leaf curl disease (CLCuD) causing viruses belong to the Begomovirus genus of the family Geminiviridae. Most begomoviruses are bipartite with two molecules of circular single stranded DNA (A and B) encapsidated in icosahedral geminate particles. However, the begomoviruses associated with CLCuD have DNA- instead of DNA-B. In this communication we report the complete genomic sequence of DNA-A component of two CLCuD-causing begomoviruses, cotton leaf curl Kokhran virus-Dabawali (CLCuKV-Dab), tomato leaf curl Bangalore virus-Cotton [Fatehabad] (ToLCBV-Cotton [Fat]) and partial sequences of two other isolates cotton leaf curl Rajasthan virus-Bangalore (CLCuRV-Ban) and cotton leaf curl Kokhran virus-Ganganagar (CLCuKV-Gang). A phylogenetic analysis of these isolates along with other related begomoviruses showed that ToLCBV-Cotton [Fat] isolate was closest to the tomato leaf curl Bangalore virus-5 (ToLCBV-Ban5) where as CLCuKV-Dab isolate was close to the cotton leaf curl Kokhran virus-Faisalabad1 (CLCuKV-Fai1), cotton leaf curl Kokhran virus-72b (CLCuKV-72b) and cotton leaf curl Kokhran virus-806b (CLCuKV-806b) isolates from Pakistan. The phylogenetic analysis further showed that the ToLCBV-Cotton [Fat] and CLCuKV-Dab isolates along with CLCuKV-Fai1, CLCuKV-72b and CLCuKV-806b are closer to the ToLCBV, tomato leaf curl Gujarat virus (ToLCGV), tomato leaf curl Gujarat virus-Varanasi (ToLCGV-Var) and tomato leaf curl Sri Lanka virus (ToLCSLV) isolates, where as cotton leaf curl Alabad virus-804a (CLCuAV-804a), cotton leaf curl Multhan virus (CLCuMV) cluster with the isolates from cotton leaf curl Rajasthan virus (CLCuRV) and okra yellow vein mosaic virus (OYVMV). These results demonstrate the extensive variability observed in this group of viruses. The AC4 ORF is the least conserved among these viruses. In order to further asses the variability in the CLCuD-causing begomoviruses, the region showing minimum similarity in the DNA-A sequence was first determined by a comparison of segments of different lengths of the aligned sequences. The results indicated that region 2411–424 (771nt) was the least conserved. A phylogenetic tree constructed using the sequences of all the CLCuD causing begomoviruses, corresponding to the least conserved region showed that they form two distinct clusters. 相似文献
8.
Interleukin-21 is a T-helper cytokine that regulates humoral immunity and cell-mediated anti-tumour responses 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Cytokines and their receptors represent key targets for therapeutic intervention. Ligands are being used to supplement cell numbers that become depleted as a result of disease (organ failure, infection) or subsequent disease treatments (i.e. chemotherapy). Conversely, the inhibition of target cell binding by cytokines is an established strategy for abrogating pathologic cellular activities common to many immunological diseases. Considerable effort in biomedical research is being focused on the cytokine families that play a dominant role in regulating immunity and then prioritizing each member for its therapeutic potential. Currently, the interleukin-2 (IL-2) family of cytokines is widely recognized for its central involvement in controlling lymphocyte function and is the most explored for medical utility. Collectively, these proteins (or their antagonists) are either marketed drugs or have received advanced testing for an impressive array of indications including cancer, infectious disease, transplantation, inflammation and allergic asthma. Here we review the current understanding of IL-21, the most recent member of this cytokine family to be discovered. As will be discussed, IL-21 shares many of the same attributes as its relatives in that it has broad immunoregulatory activity and can modulate both humoral and cell-mediated responses. Its ability to stimulate durable anti-tumour responses in mice defines one therapeutic indication that merits clinical development. 相似文献
9.
Natural killer cell differentiation: insights from knockout and transgenic mouse models and in vitro systems 总被引:7,自引:0,他引:7
Noelle Sevilir Williams Jennifer Klem Igor J. Puzanov P. V. Sivakumar John D. Schatzle Michael Bennett Vinay Kumar 《Immunological reviews》1998,165(1):47-61
Summary: In the last few years, the routine development of knockout and transgenic mice and the ease with which rare progenitor populations can be isolated from hematopoietic organs and cultured in vitro has facilitated significant advances in understanding the lineage and development of natural killer (NK) cells. Fluorescence-activated cell sorter analyses have identified a common lymphoid progenitor capable of giving rise to NK, T, and B cells, confirming the lymphoid origin of NK cells. Knockout and transgenic mouse models have pointed to an absolutely critical role for signals sent through the interleukin (IL)-2/lS receptor β (CD 122) chain and common γ (γc) chain for NK development. Such signals are likely relayed inside the cell by the tyrosine kinase Jak3, which associates with γc. Recently developed IL-15 and IL-15 receptor a knockout mice have pinpointed IL-15 as the mediator of this signal. Other mouse models have indicated an unexpected role for flt3 ligand in early NK-cell development as well as minor roles for stem cell factor and IL-7 in expanding NK-cell progenitor numbers. Finally, in vitro culture systems have proven useful in identifying the point in NK development at which each of these signals is critical. 相似文献
10.
Summary. A virus isolate causing mosaic disease of commercial sugarcane was purified to homogeneity. Electron microscopy revealed
flexuous filamentous virus particles of ca 890 × 15 nm. The virus isolate reacted positively with heterologous antiserum to
narcissus latent virus form UK, but failed to react with potyvirus group specific antiserum. N-terminal sequencing of the
intact coat protein (CP) and the tryptic peptides indicated that the virus was probably a potyvirus but distinct from several
reported potyviruses. Comparison of the 3′-terminal 1084 nucleotide sequence of the RNA genome of this virus revealed 93.6%
sequence identity in the coat protein coding region with the recently described sugarcane streak mosaic virus (Pakistani isolate).
The molecular weight of the coat protein (40 kDa) was higher than that deduced from the amino acid sequence (34 kDa). The
apparent increase in size was shown to be due to glycosylation of the coat protein which has not been reported thus far in
the family, Potyviridae. This is the first report on the molecular characterization of a virus causing mosaic disease of sugarcane in India and the
results demonstrate that the virus is a strain of sugarcane streak mosaic virus, a member of the Tritimovirus genus of the Potyviridae. We have named it sugarcane streak mosaic virus – Andhra Pradesh isolate (SCSMV-AP).
Received October 14, 1997 Accepted August 7, 1998 相似文献