全文获取类型
收费全文 | 14979篇 |
免费 | 1412篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 124篇 |
儿科学 | 624篇 |
妇产科学 | 296篇 |
基础医学 | 1865篇 |
口腔科学 | 353篇 |
临床医学 | 1645篇 |
内科学 | 2879篇 |
皮肤病学 | 191篇 |
神经病学 | 1362篇 |
特种医学 | 716篇 |
外科学 | 2171篇 |
综合类 | 376篇 |
一般理论 | 18篇 |
预防医学 | 1435篇 |
眼科学 | 402篇 |
药学 | 1090篇 |
中国医学 | 12篇 |
肿瘤学 | 891篇 |
出版年
2022年 | 141篇 |
2021年 | 244篇 |
2020年 | 158篇 |
2019年 | 252篇 |
2018年 | 340篇 |
2017年 | 267篇 |
2016年 | 281篇 |
2015年 | 344篇 |
2014年 | 442篇 |
2013年 | 619篇 |
2012年 | 837篇 |
2011年 | 813篇 |
2010年 | 505篇 |
2009年 | 450篇 |
2008年 | 718篇 |
2007年 | 751篇 |
2006年 | 742篇 |
2005年 | 681篇 |
2004年 | 714篇 |
2003年 | 577篇 |
2002年 | 606篇 |
2001年 | 372篇 |
2000年 | 350篇 |
1999年 | 336篇 |
1998年 | 261篇 |
1997年 | 220篇 |
1996年 | 233篇 |
1995年 | 158篇 |
1994年 | 192篇 |
1993年 | 166篇 |
1992年 | 295篇 |
1991年 | 262篇 |
1990年 | 216篇 |
1989年 | 224篇 |
1988年 | 213篇 |
1987年 | 209篇 |
1986年 | 197篇 |
1985年 | 178篇 |
1984年 | 131篇 |
1983年 | 106篇 |
1982年 | 100篇 |
1981年 | 94篇 |
1980年 | 108篇 |
1979年 | 90篇 |
1978年 | 87篇 |
1977年 | 85篇 |
1976年 | 99篇 |
1974年 | 75篇 |
1973年 | 95篇 |
1972年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
The effects of co-culture with human fibroblasts on human embryo development in vitro and implantation 总被引:5,自引:0,他引:5
Wetzels AM; Bastiaans BA; Hendriks JC; Goverde HJ; Punt-van der Zalm AP; Verbeet JG; Braat DD 《Human reproduction (Oxford, England)》1998,13(5):1325-1330
In a human in-vitro fertilization (IVF) programme, the effect of co-
culture of embryos with human fibroblasts was evaluated with respect to
pregnancy rate and embryo development. Patients were included in the study
after giving informed written consent. The IVF treatments were randomly
assigned by stratification of both age (<36 versus > or =36 years)
and previous IVF attempts (yes versus no). After fertilization was
established, the zygotes were transferred to a 4-well dish with or without
fibroblasts and cultured for 2 days. On the third day after ovum pick-up
(OPU), cell number and quality [5 (good) to 1 (poor)] of the embryos were
scored and a maximum of three embryos was transferred. Supernumerary
embryos of good quality were cryopreserved. The design of this study was a
group sequential trial with the objective of detecting differences between
pregnancy rates following IVF with conventional incubation or incubation in
co-culture with fibroblasts. This design included one evaluation at
half-way data collection. In the study, 148 patients had an OPU, of whom 77
were allocated to the co-culture group. There was no statistically
significant difference in pregnancy rate, cell number and embryo quality
between the two groups. The ongoing pregnancy rate per embryo transfer was
27% in co-culture and 30% in the conventional culture group. The
implantation rates per transferred embryo were 17 and 18% respectively.
Using a multivariate logistic regression model for the probability of
ongoing pregnancies, the odds ratio of co-culture, adjusted for age and
previous IVF attempts, was not statistically significant. In conclusion,
co-culture with human fibroblasts does not contribute to an improvement of
embryo quality nor to a higher pregnancy rate after IVF in an unselected
group of patients.
相似文献
152.
R M Winter M Baraitser D B Grant M A Preece C M Hall 《Journal of medical genetics》1984,21(2):124-128
Five patients from four families, including two male sibs, are reported with clinical and radiological features of the 3-M syndrome. 相似文献
153.
Characterization of the Interaction between Yersinia enterocolitica Biotype 1A and Phagocytes and Epithelial Cells In Vitro 下载免费PDF全文
Yersinia enterocolitica strains of biotype 1A are increasingly being recognized as etiological agents of gastroenteritis. However, the mechanisms by which these bacteria cause disease differ from those of highly invasive, virulence plasmid-bearing Y. enterocolitica strains and are poorly understood. We have investigated several biotype 1A strains of diverse origin for their ability to resist killing by professional phagocytes. All strains were rapidly killed by polymorphonuclear leukocytes but persisted within macrophages (activated with gamma interferon) to a significantly greater extent (survival = 40.5% +/- 17.4%) than did Escherichia coli HB101 (9.3% +/- 0.7%; P = 0.0001). Strains isolated from symptomatic patients were significantly more resistant to killing by macrophages (survival = 48.9% +/- 19.5%) than were strains obtained from food or the environment (survival = 32.1% +/- 10.3%; P = 0.04). Some strains which had been ingested by macrophages or HEp-2 epithelial cells showed a tendency to reemerge into the tissue culture medium over a period lasting several hours. This phenomenon, which we termed "escape," was observed in 14 of 15 strains of clinical origin but in only 3 of 12 nonclinical isolates (P = 0.001). The capacity of bacteria to escape from cells was not directly related to their invasive ability. To determine if escape was due to host cell lysis, we used a variety of techniques, including lactate dehydrogenase release, trypan blue exclusion, and examination of infected cells by light and electron microscopy, to measure cell viability and lysis. These studies established that biotype 1A Y. enterocolitica strains were able to escape from macrophages or epithelial cells without causing detectable cytolysis, suggesting that escape was achieved by a process resembling exocytosis. The observations that biotype 1A Y. enterocolitica strains of clinical origin are significantly more resistant to killing by macrophages and significantly more likely to escape from host cells than are strains of nonclinical origin suggest that these properties may account for the virulence of these bacteria. 相似文献
154.
P Donnan A Hutchinson R Paxton B Grant M Firth 《The British journal of general practice》1990,40(341):498-501
The efficacy of a self-help package in treating chronic anxiety was evaluated in a randomized controlled trial in which the intervention group received self-help materials in the form of an audiotape and booklet, in addition to their current treatment. The intervention was successful in terms of mean depression scores (P = 0.01), anxiety scores (P = 0.04) and general health questionnaire scores (P = 0.02) which were significantly lower for the intervention group than for the controls. In addition, the depression scores fell faster for the intervention group than for the controls. The overall mean reduction in three months in adjusted depression scores was approximately two points greater for the intervention group than for the controls (P = 0.02). Clinicians welcomed the package as a valuable addition to the therapies available for managing chronic anxiety problems. Further studies should include larger sample sizes, taking into account the non-response to postal questionnaires over time. 相似文献
155.
Broiler chickens as potential source of Campylobacter infections in humans. 总被引:23,自引:8,他引:23 下载免费PDF全文
Of 46 broiler chickens from a live poultry market in New York City, 38 (83%) harbored Campylobacter fetus subsp. jejuni in their rectal flora. The observed mean number of C. fetus per g of feces was 4.4 x 10(6). The organisms survived in the feces for at least 96 h at 4 degrees C whether stored in the gut or transferred to a vial. The best survival medium for pure cultures of C. fetus subsp.jejuni was heart infusion broth supplemented with sterile blood and kept in a microaerophilic atmosphere. 相似文献
156.
157.
158.
Multisite reproducibility of colorimetric broth microdilution method for antifungal susceptibility testing of yeast isolates. 总被引:3,自引:9,他引:3 下载免费PDF全文
M A Pfaller Q Vu M Lancaster A Espinel-Ingroff A Fothergill C Grant M R McGinnis L Pasarell M G Rinaldi L Steele-Moore 《Journal of clinical microbiology》1994,32(7):1625-1628
MICs of fluconazole and amphotericin B were determined independently for 100 coded yeast isolates by each of six laboratories to determine reproducibility of results by using a colorimetric oxidation-reduction-based broth microdilution test. In addition, each site tested five quality control isolates on at least four different occasions during the study. Results agreed within a three-dilution range (mode +/- 1 log2 dilution) for 96.2% of fluconazole tests and 92.7% of amphotericin B tests. Agreement among tests with the quality control isolates was 99.4% with fluconazole and 98.6% with amphotericin B. These results indicate that the colorimetric microdilution method is reproducible among laboratories. 相似文献
159.
160.
Successful treatment of chronic idiopathic urticaria and angioedema with cimetidine alone 总被引:1,自引:0,他引:1
Jafar Farnam M.D. J. Andrew Grant M.D. Brock G. Guernsey Pharm. D. Joseph L. Jorizzo M.D. Emil R. Petrusa Ph. D. 《The Journal of allergy and clinical immunology》1984,73(6):842-845
We have studied a 50-year-old white man with chronic urticaria and angioedema who has responded to treatment with cimetidine alone for over 2 yr. In a double-blind, placebo-controlled study, cimetidine alone was at least as effective as chlorpheniramine in relief of urticaria and angioedema. Additionally, cimetidine significantly inhibited (p less than 0.01) the wheal response to histamine when it was compared to placebo. The inhibition of wheal response to histamine by cimetidine was significantly higher (p less than 0.05) than chlorpheniramine. The presence of predominantly H2- rather than H1-histamine receptors in the cutaneous blood vessels may be responsible for the therapeutic effects of cimetidine in this patient. 相似文献