全文获取类型
收费全文 | 12535篇 |
免费 | 862篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 87篇 |
儿科学 | 375篇 |
妇产科学 | 396篇 |
基础医学 | 1664篇 |
口腔科学 | 210篇 |
临床医学 | 822篇 |
内科学 | 2530篇 |
皮肤病学 | 255篇 |
神经病学 | 994篇 |
特种医学 | 409篇 |
外国民族医学 | 1篇 |
外科学 | 1833篇 |
综合类 | 159篇 |
一般理论 | 7篇 |
预防医学 | 1073篇 |
眼科学 | 256篇 |
药学 | 853篇 |
中国医学 | 60篇 |
肿瘤学 | 1488篇 |
出版年
2023年 | 45篇 |
2022年 | 141篇 |
2021年 | 289篇 |
2020年 | 189篇 |
2019年 | 215篇 |
2018年 | 317篇 |
2017年 | 221篇 |
2016年 | 232篇 |
2015年 | 308篇 |
2014年 | 378篇 |
2013年 | 535篇 |
2012年 | 671篇 |
2011年 | 679篇 |
2010年 | 473篇 |
2009年 | 400篇 |
2008年 | 609篇 |
2007年 | 631篇 |
2006年 | 607篇 |
2005年 | 533篇 |
2004年 | 568篇 |
2003年 | 535篇 |
2002年 | 569篇 |
2001年 | 493篇 |
2000年 | 442篇 |
1999年 | 400篇 |
1998年 | 167篇 |
1997年 | 129篇 |
1996年 | 128篇 |
1995年 | 127篇 |
1994年 | 94篇 |
1993年 | 93篇 |
1992年 | 236篇 |
1991年 | 213篇 |
1990年 | 206篇 |
1989年 | 208篇 |
1988年 | 161篇 |
1987年 | 128篇 |
1986年 | 141篇 |
1985年 | 122篇 |
1984年 | 97篇 |
1983年 | 76篇 |
1982年 | 47篇 |
1981年 | 44篇 |
1979年 | 53篇 |
1975年 | 35篇 |
1974年 | 37篇 |
1973年 | 35篇 |
1969年 | 37篇 |
1968年 | 41篇 |
1967年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
This study investigated whether feeding different wheat varieties to laying hens could influence colonization with the intestinal spirochaete Brachyspira intermedia. Fifty ISA-Brown laying hens were divided into two groups. One group were fed a laying-hen diet formulated with wheat variety Westonia, and one were fed the diet incorporating variety Stilleto. Each group was divided into 15 hens experimentally infected with B. intermedia and 10 uninfected controls. The 30 infected hens were housed in individual cages in one room, and the controls were similarly housed in another room. Following administration of cultures of B. intermedia strain HB60 by crop-tube over 3 days, cloacal swabs were taken for spirochaete culture every 3 to 4 days. The water content of caecal faeces, and egg production and body weight were measured weekly. The hens were killed after 4 weeks, the caeca cultured for spirochaetes and the viscosity of the ileal contents measured. A total of 48/120 (40%) of the excreta samples from infected hens fed Westonia contained B. intermedia, compared with 21/120 (17.5%) for Stiletto (P = 0.0002). The ileal viscosity of hens fed Westonia also was higher (P = 0.048), but viscosity was not clearly related to the non-starch polysaccharide (NSP) content of the wheats. Westonia had a slightly higher total NSP content than Stiletto, but the ratio of soluble to insoluble NSP was lower. Infected hens developed wetter excreta, but neither infection nor diet altered egg production. In conclusion, the wheat variety can influence colonization with B. intermedia, apparently through diet-related alterations in the intestinal microenvironment. 相似文献
82.
Crosignani Pier Giorgio; De Cecco Luigi; Gastaldi Attilio; Venturini Pier Luigi; Oldani Sabina; Vegetti Walter; Semino Antonio; Commare Paolo La; Vercellini Paolo 《Human reproduction (Oxford, England)》1996,11(12):2732-2735
An open-label randomized pilot study was conducted to evaluatethe efficacy and acceptability of 6 months treatment with leuprolidein a 3-monthly versus a monthly i.m. depot injection for therelief of chronic pelvic pain in women with endometriosis. Atotal of 30 women aged 18-38 years were allocated to the 3-monthlydepot arm (n = 15) or to the monthly depot arm (n = 15) afterlaparoscopic diagnosis of pelvic endometriosis. Mean (SD) deepdys-pareunia scores according to a 03 point verbal ratingscale decreased from 1.8 (0.9) at baseline to 1.3 (0.7) at theend of treatment in the 3-monthly depot group and from 2.1 (1.2)to 13 (0.7) in the monthly depot group. Correspondingvalues in non-menstrual pain scores fell from 2.1 (0.6) to 1.1(03), and from 2.1 (0.8) to 1.2 (0.4) respectively, withoutstatistically significant differences between the groups. Serumluteinizing hormone (LH) and 17-oestradiol concentrations weresignificantly suppressed at 12 and 24 weeks compared with baselinevalues, without differences between the groups. The monthlydepot caused a slightly more marked inhibition of serum folliclestimulating hormone (FSH) levels with respect to the 3-monthlypreparation. Mean (SD) endometriosis scores at baseline andat 6-month follow-up laparoscopy were respectively 32.8 (25.1)and 12.2 (9.3) in the 3-monthly depot group and 29.0 (22.7)and 13.1 (15.3) in the monthly depot group (paired Mest, P 0.05). Mean percentage decrease in lumbar spine bone mineraldensity was 5.2% in the former and 4.9% in the latter subjects.In the 3-monthly depot group, 13 women graded the tolerabilityof their treatment schedule as good compared withseven in the monthly depot group (2 = 5.40, P = 0.02). 相似文献
83.
R. T. Withers N. O. Whittingham K. I. Norton J. La Forgia M. W. Ellis A. Crockett 《European journal of applied physiology》1987,56(2):169-180
Summary Ninety-one percent (n=182) of the female members of South Australian representative squads in 14 sports volunteered to act as subjects. Twenty-seven percent of them had represented Australia. The underwater weighing method together with the measurement of residual volume (RV) by helium dilution were used to determine body density (BD); the percent body fat (% BF) was then computed according to Siri.A stepwise multiple regression analysis yielded a correlation coefficient (R) of 0.863 between the criterion (BD) and the best weighted sum of predictors (anthropometric variables): BD (g·cm–3)=1.14075–0.04959 (log10 triceps, subscapular, supraspinale and calf skinfolds in mm)+0.00044 (age in decimal years)–0.000612 (waist girth in cm)+0.000284 (height in cm)–0.000505 (gluteal girth in cm)+0.000331 (breast girth in cm).Only those predictors which resulted in a statistically significant increase inR (p0.05) were included. The standard error of estimate of 0.00597 g · cm–3 was equivalent to 2.7% BF at the mean. This equation was shown to be largely population specific. There was a range of 7.6–35.8% of BF and the overall mean of 18.5% was significantly lower (p<0.001) than that of 23.4% obtained on a moderately active reference sample of similar age (n=135). If group sizes of only one or two are regarded as too small for meaningful comparison, then the lowest mean of 13.5% was achieved by the long-distance runners (n=14). The highest averages were registered by the heavyweight rowers (24.2%;n=7) and soccer players (22.0%;n=11). The overall average for games players (n=107) was 19.4%.This study was supported by a grant from the National Health and Medical Research Council of Australia 相似文献
84.
CD1a and antitumour immune response 总被引:3,自引:0,他引:3
Primary immune response is based on the capacity of local professional antigen-presenting cells (whose prototype is represented by dendritic cells, DCs) to take up and present antigens to selected clones of T cells, but also to non-specific effector cells such as macrophages or natural killer cells. The four CD1 proteins, all of which share a limited homology to class I MHC proteins, are differently expressed in various cell types, of both mesenchymal and, as recently described, epithelial lineage. Regarding the role of CD1 molecules in the anti-tumour response, it has been reported that CD1+ dendritic cells are involved in the first steps of the primary immune response in a number of malignancies. Moreover, the presence of a high number of DCs in the tumoral or peritumoral area, as well as in the draining lymph nodes, has been shown to correlate with a better prognosis. A recent report on the presence of CD1a in metaplastic epithelial cells of Barrett esophagus introduced new questions about CD1a expression patterns. Moreover, the strong correlation between the lack of CD1a+ cells and the malignant evolution of the lesion may indicate a possible role of non-professional APCs in mediating and/or potentiating immune responses to tumours. 相似文献
85.
I Get by with a Little Help from my Family and Friends: Adolescents' Support for Diabetes Care 总被引:5,自引:6,他引:5
La Greca Annette M.; Auslander Wendy F.; Greco Peggy; Spetter Dante; Fisher Edwin B. Jr.; Santiago Julio V. 《Journal of pediatric psychology》1995,20(4):449-476
Evaluated and compared the support provided by family membersand friends for adolescents' diabetes care. Family and friendsupport also were examined in relation to other measures ofsocial support, to demographic variables (age, gender, durationof diabetes) and to adherence. Using a structured interview,74 adolescents with diabetes described the ways that familymembers and friends provided support for diabetes management(insulin shots, blood glucose monitoring, eating proper meals,exercise), and for helping them to "feel good about their diabetes."Families provided more support than friends for three managementtasks (insulin injections, blood glucose monitoring, meals);this support was largely instrumental. In contrast, friendsprovided more emotional support for diabetes than families.Greater family support was related to younger age, shorter diseaseduration, and better treatment adherence. Implications of thefindings include encouraging parents to remain involved in adolescents'treatment management, and involving peers as supportive companionsfor meals and exercise. 相似文献
86.
87.
88.
89.
Androgen receptor YAC transgenic mice carrying CAG 45 alleles show trinucleotide repeat instability 总被引:1,自引:15,他引:1
La Spada AR; Peterson KR; Meadows SA; McClain ME; Jeng G; Chmelar RS; Haugen HA; Chen K; Singer MJ; Moore D; Trask BJ; Fischbeck KH; Clegg CH; McKnight GS 《Human molecular genetics》1998,7(6):959-967
X-linked spinal and bulbar muscular atrophy (SBMA) is caused by a CAG
repeat expansion in the first exon of the androgen receptor (AR) gene.
Disease-associated alleles (37-66 CAGs) change in length when transmitted
from parents to offspring, with a significantly greater tendency to shift
size when inherited paternally. As transgenic mice carrying human AR cDNAs
with 45 and 66 CAG repeats do not display repeat instability, we attempted
to model trinucleotide repeat instability by generating transgenic mice
with yeast artificial chromosomes (YACs) carrying AR CAG repeat expansions
in their genomic context. Studies of independent lines of AR YAC transgenic
mice with CAG 45 alleles reveal intergenerational instability at an overall
rate of approximately 10%. We also find that the 45 CAG repeat tracts are
significantly more unstable with maternal transmission and as the
transmitting mother ages. Of all the CAG/CTG repeat transgenic mice
produced to date the AR YAC CAG 45 mice are unstable with the smallest
trinucleotide repeat mutations, suggesting that the length threshold for
repeat instability in the mouse may be lowered by including the appropriate
flanking human DNA sequences. By sequence-tagged site content analysis and
long range mapping we determined that one unstable transgenic line has
integrated an approximately 70 kb segment of the AR locus due to
fragmentation of the AR YAC. Identification of the cis - acting elements
that permit CAG tract instability and the trans -acting factors that
modulate repeat instability in the AR YAC CAG 45 mice may provide insights
into the molecular basis of trinucleotide repeat instability in humans.
相似文献
90.
Comparison of Track XI fluorometric immunoassay with Bio-EnzaBead enzyme-linked immunosorbent assay for detection of serum antibody to mouse hepatitis virus.
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)
M C La Regina J Lonigro L Woods W C Hall R E Doyle 《Journal of clinical microbiology》1988,26(3):573-575
The Track XI system (Microbiological Associates, Bethesda, Md.) was compared with the Bio-EnzaBead assay (Organon Teknika, Durham, N.C.) for the detection of antibody to mouse hepatitis virus (MHV). Strain A/J mice were inoculated intranasally with MHV type 3. Sera were collected at 1, 2, 4, and 9 weeks postinoculation and tested. Individual serum samples were retested twice by each method. The results suggested that the Track XI system was more sensitive and reliable than the Bio-EnzaBead assay in detecting antibody to MHV type 3 in individual serum samples from A/J mice. 相似文献