全文获取类型
收费全文 | 6756篇 |
免费 | 664篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 201篇 |
妇产科学 | 143篇 |
基础医学 | 838篇 |
口腔科学 | 205篇 |
临床医学 | 765篇 |
内科学 | 1445篇 |
皮肤病学 | 99篇 |
神经病学 | 557篇 |
特种医学 | 235篇 |
外科学 | 660篇 |
综合类 | 106篇 |
一般理论 | 4篇 |
预防医学 | 811篇 |
眼科学 | 176篇 |
药学 | 668篇 |
中国医学 | 5篇 |
肿瘤学 | 484篇 |
出版年
2022年 | 36篇 |
2021年 | 122篇 |
2020年 | 73篇 |
2019年 | 100篇 |
2018年 | 107篇 |
2017年 | 76篇 |
2016年 | 86篇 |
2015年 | 131篇 |
2014年 | 160篇 |
2013年 | 231篇 |
2012年 | 301篇 |
2011年 | 287篇 |
2010年 | 183篇 |
2009年 | 156篇 |
2008年 | 295篇 |
2007年 | 316篇 |
2006年 | 304篇 |
2005年 | 323篇 |
2004年 | 324篇 |
2003年 | 285篇 |
2002年 | 285篇 |
2001年 | 264篇 |
2000年 | 247篇 |
1999年 | 203篇 |
1998年 | 109篇 |
1997年 | 95篇 |
1996年 | 80篇 |
1995年 | 76篇 |
1994年 | 75篇 |
1993年 | 82篇 |
1992年 | 158篇 |
1991年 | 158篇 |
1990年 | 130篇 |
1989年 | 134篇 |
1988年 | 129篇 |
1987年 | 123篇 |
1986年 | 111篇 |
1985年 | 109篇 |
1984年 | 85篇 |
1983年 | 86篇 |
1982年 | 63篇 |
1981年 | 56篇 |
1980年 | 38篇 |
1979年 | 54篇 |
1978年 | 56篇 |
1976年 | 46篇 |
1975年 | 35篇 |
1974年 | 38篇 |
1973年 | 36篇 |
1972年 | 37篇 |
排序方式: 共有7428条查询结果,搜索用时 15 毫秒
51.
Image analysis derived ploidy and proliferation indices in soft tissue sarcomas: comparison with clinical outcome.
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
AIMS--To compare prognostic information obtained by image analysis cytometry of paraffin wax embedded soft tissue sarcomas with conventional assessment. METHODS--A CAS 200 image analyser was used to determine DNA content of Feulgen stained cytology preparations and tissue sections and to quantify immunostaining by Ki67 and PC10 antibodies. A mitotic count in 50 high power fields was undertaken and histological grade assigned by the Trojani system. Clinical details including follow up and outcome were obtained by case note review. The Kruskal-Wallis one way analysis test, Spearman rho significance test, Kaplan-Meier method, and log-rank test were applied in statistical analysis. RESULTS--Ploidy status, DNA index, 2.5c exceeding rate, 5c exceeding rate, mitotic count and Trojani grade all correlated significantly with clinical outcome. The relation between Ki67 index and outcome did not reach significance. The PC10 index and outcome were not related. Only 2.5c exceeding rate, 5c exceeding rate, and mitotic count correlated significantly with Trojani grade. CONCLUSIONS--DNA content determination of soft tissue sarcomas by image analysis provides quantifiable information of benefit in prediction of outcome. Larger series are required to determine the independent value of ploidy. In this study quantification of anti-Ki67 and anti-PC10 immunostaining was not of prognostic benefit) by contrast with mitotic count and Trojani grade. 相似文献
52.
Chickens infected with infectious laryngotracheitis virus (ILTV) responded by producing virus-specific IgG in their sera, which increased steadily in concentration, but with slight fluctuations, until peak titres were reached 40 days post-inoculation (pi), immediately prior to the second challenge. Thereafter, following an initial lag, concentrations continued to increase for 21 days before falling slightly at the end of the experiment. In contrast, peak concentrations of ILTV-specific IgM were reached 6 days pi falling to their lowest levels by day 16, before increasing to a second peak and trough on days 26 and 32, respectively. This cyclical production of ILTV-specific IgM was confirmed in a second experiment. The pattern of production of ILTV-specific IgG, IgM and IgA, detected in tracheal washings, occurred in the same cyclical manner. IgM was produced first, peak concentrations being detected 5 days pi, whereas IgG and IgA did not peak until 10 days pi, with second peaks of each class being detected 25-30 days pi. The possibility that the cyclical antibody class response to ILTV infection is related to the previously reported intermittent pattern of re-excretion of the virus is discussed. 相似文献
53.
Evaluation of four methods for detection of group B streptococcal colonization. 总被引:1,自引:3,他引:1
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Four methods (streak plate, pour plate, selective broth, and direct fluorescent-antibody staining) were evaluated for their ability to detect group B streptococcal colonization in parturient women and their offspring. When colonization was defined as a positive culture by any method from any site, selective broth was the most sensitive method, detecting 100% of colonized mothers and infants at birth and 48 h of age. This method failed to detect only one colonized individual (infant at 24 h of age). The other three methods detected from 20 to 56% of colonized individuals. 相似文献
54.
Antibodies detectable by counterimmunoelectrophoresis against Bacteroides antigens in serum of patients with inflammatory bowel disease.
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C J Helphingstine D J Hentges B J Campbell J Butt J T Barrett 《Journal of clinical microbiology》1979,9(3):373-378
Heat-extracted antigens from seven species of Bacteroides were used in passive hemagglutination and counterimmunoelectrophoretic tests. Sera from 87 normal persons (group I) and 15 patients with ulcerative colitis (group II) were of low and equal reactivity in passive hemagglutination tests; all positive tests were eliminated by 2-mercaptoethanol reduction of the sera. When these same sera were tested by counterimmunoelectrophoresis with six of the Bacteroides antigens, no significant difference in the percentage of positive reactions was noted. However, using the chi-square test, the seventh antigen, prepared from Bacteroides vulgatus, successfully distinguished the two populations at the 0.025 level. Counterimmunoelectrophoretic tests with the B. vulgatus antigen also provided a means to separate the patients in group II with active disease from those in remission at a P value of 0.01. All the sera from 12 patients with defined Crohn's disease activity indexes reacted with the B. vulgatus antigen in counterimmunoelectrophoretic tests. Reduction and alkylation of patient sera with 2-mercaptoethanol and iodoacetamide removed detectable antibody in 78% of the samples, which suggested a dominant role of immunoglobulin M in the response to Bacteroides antigens. 相似文献
55.
Defective interfering Semliki Forest virus (DI SFV) inhibited virus RNA and virus polypeptide synthesis in cells coinfected with standard virus but did not delay or alter kinetics of RNA synthesis. Inhibition of polypeptide synthesis was 20-fold greater than that of RNA synthesis which presumably reflected the amplification resulting from cumulative translation of mRNAs. At high concentration, DI virus p12e inhibited the shutoff of host protein synthesis and allowed no synthesis of structural or nonstructural polypeptides. Dilution of DI virus restored the inhibition of host protein synthesis but further dilution was necessary before virus-specified polypeptide synthesis could be demonstrated. Another DI virus (p20a) with the same interference titre as p12e also inhibited shutoff of host protein synthesis but synthesis of virus-induced polypeptides was inhibited differentially: significant amounts of polypeptides comigrating with the structural precursor polypeptide p62 and the nonstructural polypeptide nsp63 were present and the synthesis of nsp90 was little affected at any concentration of DI virus p20a tested. None of the DI viruses tested induced the synthesis of any viral or novel polypeptide. It was concluded that DI SFV preparations have qualitatively different interfering activities in relation to their effects on virus and host cell polypeptide synthesis. 相似文献
56.
M V Cano J F Perz A S Craig M Liu G M Lyon M E Brandt T J Lott B A Lasker F F Barrett M M McNeil W Schaffner R A Hajjeh 《Medical mycology》2005,43(3):219-225
This is a cohort study of pediatric outpatients receiving total parenteral nutrition (TPN) and follow-up care in a Tennessee hospital between January and June 1999. The study was conducted following an increase in the incidence of candidemia. Of 13 children receiving home TPN, five had candidemia; three were due to Candida parapsilosis. Case patients were more likely to have an underlying hematologic disease (P = 0.02) as well as previous history of fungemia (P = 0.02). Two case patients had successive candidemia episodes 3 months apart; karyotypes and RAPD profiles of each patient's successive C. parapsilosis isolates were similar. Candida spp. were frequently detected in hand cultures from cohort members (four of 10) and family member caregivers (nine of 11); C parapsilosis was isolated from five caregivers. Our findings underscore the challenges of maintaining stringent infection control practices in the home health care setting and suggest the need for more intensive follow-up and coordination of home TPN therapy among pediatric patients. 相似文献
57.
Mast cells and basophils play a fundamental role in the pathogenesis of allergic disease, although their physiologic role is largely unknown. A large body of evidence now indicates that the properties of mast cells are dependent on the tissue and species from which they are derived. Such mast cell heterogeneity encompasses differences in morphology, development, cytochemistry, and function. The evidence for such heterogeneity, and some of its clinical implications, is discussed. 相似文献
58.
Double nondisjunction during karyotypic progression of chemically induced Syrian hamster cell lines 总被引:1,自引:0,他引:1
The karyotypic evolution of three chemically induced cell lines of Syrian hamster embryo in culture are described. The only karyotypic alteration of one clone was a trisomy of chromosome #11, which presumably arose by nondisjunction after carcinogen treatment. A pure population of cells with the trisomy was observed repeatedly upon karyotyping of cells at the first three passages after cloning. However, at a late passage, apparently normal diploid cells appeared in the culture, which we propose resulted from a second nondisjunction of one chromosome #11, reverting the cells from trisomy 11 to disomy 11. The karyotypic evolution of two other cell lines also involved double nondisjunction, which resulted in duplication of a translocated chromosome and concurrent loss of the normal nonrearranged chromosome. Taken together with the reported findings of others, the results indicate that double nondisjunction is a mechanism in karyotypic progression during neoplastic development. 相似文献
59.
Summary Aconitase and NAD linked isocitrate dehydrogenase were present in Ascaris lumbricoides muscle at only very low activities, whilst there were significant levels of citrate synthase, NADP linked isocitrate dehydrogenase, 2-oxoglutarate dehydrogenase and succinic thiokinase. Pyruvate dehydrogenase was present in A. lumbricoides muscle at levels comparable with mammalian tissues and results suggest that it is modulated via a phosphotransferase/phosphatase system.The tricarboxylic acid cycle intermediates, citrate, isocitrate and 2-oxoglutarate were all detected in freeze clamped muscle, but their steady state levels were considerably lower than those found in mammalian tissues. 相似文献
60.
Fugger EF; Black SH; Keyvanfar K; Schulman JD 《Human reproduction (Oxford, England)》1998,13(9):2367-2370
The world's first deliveries of normal babies after use of flow cytometric
separated human sperm cells (MicroSort) for preconception gender selection
are reported. Offspring were of the desired female gender in 92.9% of the
pregnancies. Most of these pregnancies and births were achieved after
simple intrauterine insemination.
相似文献