全文获取类型
收费全文 | 9635篇 |
免费 | 671篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 56篇 |
儿科学 | 165篇 |
妇产科学 | 222篇 |
基础医学 | 1314篇 |
口腔科学 | 233篇 |
临床医学 | 822篇 |
内科学 | 2371篇 |
皮肤病学 | 113篇 |
神经病学 | 1164篇 |
特种医学 | 347篇 |
外科学 | 1027篇 |
综合类 | 122篇 |
一般理论 | 10篇 |
预防医学 | 913篇 |
眼科学 | 341篇 |
药学 | 667篇 |
1篇 | |
中国医学 | 8篇 |
肿瘤学 | 439篇 |
出版年
2023年 | 66篇 |
2022年 | 94篇 |
2021年 | 190篇 |
2020年 | 125篇 |
2019年 | 176篇 |
2018年 | 197篇 |
2017年 | 123篇 |
2016年 | 169篇 |
2015年 | 165篇 |
2014年 | 224篇 |
2013年 | 400篇 |
2012年 | 499篇 |
2011年 | 549篇 |
2010年 | 325篇 |
2009年 | 319篇 |
2008年 | 489篇 |
2007年 | 537篇 |
2006年 | 511篇 |
2005年 | 573篇 |
2004年 | 470篇 |
2003年 | 429篇 |
2002年 | 436篇 |
2001年 | 207篇 |
2000年 | 218篇 |
1999年 | 202篇 |
1998年 | 136篇 |
1997年 | 96篇 |
1996年 | 89篇 |
1995年 | 78篇 |
1994年 | 63篇 |
1993年 | 65篇 |
1992年 | 140篇 |
1991年 | 129篇 |
1990年 | 104篇 |
1989年 | 89篇 |
1988年 | 86篇 |
1987年 | 69篇 |
1986年 | 78篇 |
1985年 | 81篇 |
1984年 | 56篇 |
1983年 | 69篇 |
1982年 | 69篇 |
1981年 | 69篇 |
1980年 | 55篇 |
1979年 | 61篇 |
1978年 | 63篇 |
1977年 | 58篇 |
1975年 | 52篇 |
1974年 | 53篇 |
1970年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
61.
We examined the factors influencing maternal food intake and pup growth in Norway rats. Mother rats allowed pups in naturally large litters to grow at a slower rate than pups in naturally small litters. Pups reared by dams in a warm ambience (26°C) gained weight more slowly than dams at 22°C, and maternal food intake but not weight gain was depressed in the high ambient temperature. Pup growth at 18°C was unimpaired, with those dams eating no more and gaining no less weight than dams at 22°C. Nest material, however, was found to be essential for the successful rearing of young at cooler ambient temperatures. While restriction of food during gestation resulted in a marginally lower weight gain for the pups during the first 2 weeks postpartum, the dams appeared not to mobilize corporal stores or increase their food intake during lactation. Heavy body weight mothers did not eat any more, nor did they gain any less weight nor rear larger pups than light body weight dams. Rat mothers increased their consumption of a diet diluted with non-nutritive fiber to equal the nutritive intake of their controls, with their pups not differing in their growth rate. Pups reared by dams eating a high quality diet grew faster than pups with dams on the control diet. Food intake by mother rats is required during lactation relative to the amount of milk that is delivered to the pups, rather than to an absolute amount of food. Lactating females with a concurrent pregnancy neither increase their food intake nor appear to mobilize their corporal stores to deal with the added energetic drain of pregnancy. Indeed, their young grew somewhat more quickly than pups nursed by dams that were simply lactating. Taken as a whole, these results suggest that Norway rat dams apparently do not monitor and defend a maximal pup growth rate. Rather, rat dams seem to continue to defend their own homeostasis, and by doing so, allow the young to grow and survive under a wide variety of circumstances. 相似文献
62.
Differentiation of Strains of Infectious Bovine Rhinotracheitis Virus by Neutralization Kinetics with Late 19S Rabbit Antibodies 总被引:2,自引:0,他引:2 下载免费PDF全文
Two vaccine, two respiratory (infectious bovine rhinotracheitis [IBR]), and two genital (infectious pustular vulvovaginitis [IPV]) strains of infectious bovine rhinotracheitis virus were compared by neutralization kinetics using late 19S antibody (AB). The two vaccine strains were indistinguishable from one another, but were neutralized far more rapidly than the other four strains when either anti-IBR or anti-IPV 19S AB was used. The two IPV strains were indistinguishable from one another, but were neutralized significantly more rapidly than the two IBR strains when anti-IBR 19S AB was used. The 2 IBR strains were neutralized at a similar rate with the latter globulin preparation. Almost identical results were obtained with anti-IPV 19S AB, except that one IPV strain was neutralized at a rate similar to the IBR strains. However, when early and late rabbit 7S AB were used, IBR strains could not be distinguished from IPV strains by neutralization kinetics. Preliminary experiments indicated that both early and late 19S rabbit antibodies neutralized the homologous strain more rapidly than the heterologous strain, but the difference was more noticeable with late 19S AB. It was also determined that neutralization of IBR-IPV virus by specific early and late 19S rabbit AB and early 7S rabbit AB was markedly enhanced by guinea pig complement. Neutralization of this virus by late 7S AB, however, was only slightly enhanced by complement. These results suggest that vaccine strains of IBR-IPV virus may be distinguished by neutralization kinetics with late 19S rabbit AB, and that genital and respiratory strains may possibly also be distinguishable with some 19S AB preparations. 相似文献
63.
Mark H. Pollack Michael W. Otto Gary S. Sachs Andrew Leon M. Katherine Shear Joseph A. Deltito Martin B. Keller Jerrold F. Rosenbaum 《Journal of affective disorders》1994,30(4):273-281
This study examines clinical predictors of outcome for patients with panic disorder and depression in a 16 week, placebo-controlled trial of alprazolam and imipramine (n = 126). Baseline global severity of illness and phobic avoidance were differentially predictive of acute response to treatment. Patients in the mild to moderate range of global distress experienced smaller degrees of improvement on alprazolam than on imipramine at week 4. At endpoint, the relative effectiveness of the active medication versus placebo was diminished in patients with higher levels of phobic avoidance. This relationship was not evident for completers, suggesting that the adverse effects of avoidance on outcome after sustained treatment was reduced. 相似文献
64.
E.G. De la Concha M. Fernandez-Arquero J.L. Mendoza L. Conejero M.A. Figueredo J. Perez de la Sema M. Diaz-Rubio A. Ruiz de Leon 《Tissue antigens》1998,52(4):381-384
Abstract: Achalasia is a motor disorder of the esophagus resulting in functional obstruction. The cause of the lesion is unknown although genetic and immunologic factors have been suggested. An association with serological HLA epitopes has been previously reported. In this study, we have further examined this HLA class II association with susceptibility to achalasia by DNA based methods. Achalasia patients ( n =40) and healthy controls ( n = 275), all Caucasians and unrelated, were included in the analysis. The strongest associations were with HLA-DQAl*0101 and two HLA-DQαβ heterodimers having their a chain encoded by this allele. Moreover, relative risk was significantly higher in DQAl*0101 homozygotes as compared to heterozygotes and results suggested that DQB1*02 may have a protective role. 相似文献
65.
Positional cloning of the gene for X-linked retinitis pigmentosa 3: homology with the guanine-nucleotide-exchange factor RCC1 总被引:6,自引:7,他引:6
Roepman R; van Duijnhoven G; Rosenberg T; Pinckers AJ; Bleeker-Wagemakers LM; Bergen AA; Post J; Beck A; Reinhardt R; Ropers HH; Cremers FP; Berger W 《Human molecular genetics》1996,5(7):1035-1041
The gene for retinitis pigmentosa 3 (RP3), the most frequent form of X-
linked RP (XLRP), has been mapped previously to a chromosome interval of
less than 1000 kbp between the DXS1110 marker and the OTC locus at
Xp21.1-p11.4. Employing a novel technique, YAC Representation Hybridization
(YRH)', we have recently identified a small XLRP associated microdeletion
in this interval, as well as several putative exons including the 3' end of
a gene that was truncated by the deletion. cDNA library screening and
sequencing of a cosmid centromeric to the deletion has now enabled us to
identify numerous additional exons and to detect several point mutations in
patients with XLRP. The predicted gene product shows homology to RCC1, the
guanine-nucleotide- exchange factor (GEF) of the Ras-like GTPase Ran. Our
findings suggest that we have cloned the long-sought RP3 gene, and that it
may encode the GEF of a retina-specific GTP-binding protein.
相似文献
66.
Localization of a novel X-linked congenital stationary night blindness locus: close linkage to the RP3 type retinitis pigmentosa gene region 总被引:1,自引:0,他引:1
Bergen Arthur A.B.; Brink Jacoline B.ten; Riemslag Frans; Schuurman Ellen J.M.; Tijmes Nel 《Human molecular genetics》1995,4(5):931-935
X-linked congenital stationary night blindness (CSNBX) is anon-progressive retinal disorder characterized by decreasedvisual acuity and loss of night vision. CSNBX Is clinicallyheterogeneous with respect to the involvement of retinal rodsand/or cones in the disease. in this study, we localize a newlocus for CSNBX to Xp21.1, thus providing evidence that CSNBXis also genetically heterogeneous. A clear correlation betweendifferent genotypes and phenotypes cannot be found yet. Thenew CSNBX gene described here is closely linked to the X-linkedretinitis pigmentosa type 3 gene region, which supports thehypothesis that there may be a functional relationship betweencongenital stationary night blindness and retinitis pigmentosa. 相似文献
67.
Losi L Scarselli A Benatti P Ponz de Leon M Roncucci L Pedroni M Borghi F Lamberti I Rossi G Marino M Ponti G Zangardi G Menigatti M Di Gregorio C 《Pathology, research and practice》2004,200(5):371-377
The main purpose of this study was to examine the expression of mucins and mismatch repair proteins in colorectal carcinomas. The immunohistochemical distribution of apomucins MUC2, MUC5AC, and the expression of MLH1 and MSH2 proteins were examined in 76 mucinous and 60 non-mucinous colorectal carcinomas. MUC2 was noted in all mucinous carcinomas, whereas MUC5AC was present in 41 cases only (54%). In non-mucinous carcinomas, MUC2 was expressed in 61.7% of the tumors; by contrast, MUC5AC was present in 20% of the cases. The expression level of apomucins was significantly different in mucinous and non-mucinous lesions (p<0.001). Twenty-seven (35.5%) of the mucinous carcinomas showed no MLH1 expression, whereas 11 (18.3%) of the non-mucinous tumors did. This difference was statistically significant (p<0.005). Altered expression of MSH2 protein was never observed. The lack of MLH1 expression was considerably more frequent in carcinomas with secretion of MUC5AC (p<0.005). Our study has demonstrated this close relationship by immunohistochemical methods. In summary, our data show: (1) differences in the expression of mucins between mucinous and non-mucinous tumors; (2) a high frequency of altered MLH1 protein expression (35.5%) in mucinous carcinomas; (3) a significant relationship between the presence of MUC5AC and the altered expression of MLH1 protein in colorectal carcinomas. 相似文献
68.
Fabrice Bonnet Anne-Christine Jouvencel Marie Parrens Magali Joblon Leon Emmanuelle Cotto Isabelle Garrigue Philippe Morlat Jacques Beylot Hervé Fleury Marie-Edith Lafon 《Journal of clinical virology》2006,36(4):258-263
BACKGROUND: Epstein-Barr virus (EBV) may be causally associated with non-Hodgkin Lymphoma (NHL) in HIV-infected patients. OBJECTIVES: To compare EBV load in whole blood in AIDS-NHL patients, HIV non-AIDS patients and non-HIV-infected persons, and to prospectively measure EBV load in whole blood in AIDS-NHL patients. STUDY DESIGN: Longitudinal and prospective study. RESULTS: We observed no statistical difference in EBV load between AIDS-NHL (3.69log(10) copies/mL [interquartile range (IQR): 2.89-4.27]) and HIV non-AIDS patients (3.08log(10) copies/mL [IQR: 1.29-3.57]) but AIDS-NHL patients had significantly higher EBV loads than HIV-negative controls (1.19log(10) copies/mL [IQR: 0.00-3.29]). We noticed an inverse correlation between CD4+ lymphocytes count and EBV load in patients with AIDS-NHL (r(2)=0.41, P=0.01). In the longitudinal study, the mean EBV load three months after NHL diagnosis decreased significantly (mean difference=-1.69log(10) copies/mL [95% confidence interval: -0.32; -3.04]; P=0.03) under chemotherapy but was still elevated in patients with relapses or no response to chemotherapy. CONCLUSION: Although EBV load seems a suboptimal marker for the diagnosis of AIDS-NHL, we observed a significant decrease of EBV load in patients treated with chemotherapy and a strong association between NHL outcome and EBV load in whole blood. 相似文献
69.
70.