全文获取类型
收费全文 | 1845篇 |
免费 | 95篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 102篇 |
妇产科学 | 105篇 |
基础医学 | 177篇 |
口腔科学 | 47篇 |
临床医学 | 193篇 |
内科学 | 377篇 |
皮肤病学 | 47篇 |
神经病学 | 44篇 |
特种医学 | 156篇 |
外科学 | 173篇 |
综合类 | 136篇 |
预防医学 | 152篇 |
眼科学 | 12篇 |
药学 | 107篇 |
1篇 | |
中国医学 | 74篇 |
肿瘤学 | 37篇 |
出版年
2021年 | 22篇 |
2020年 | 14篇 |
2018年 | 13篇 |
2017年 | 24篇 |
2016年 | 16篇 |
2015年 | 34篇 |
2014年 | 49篇 |
2013年 | 49篇 |
2012年 | 78篇 |
2011年 | 62篇 |
2010年 | 64篇 |
2009年 | 54篇 |
2008年 | 61篇 |
2007年 | 52篇 |
2006年 | 49篇 |
2005年 | 35篇 |
2004年 | 36篇 |
2003年 | 26篇 |
2002年 | 30篇 |
2001年 | 47篇 |
2000年 | 28篇 |
1999年 | 35篇 |
1998年 | 45篇 |
1997年 | 56篇 |
1996年 | 49篇 |
1995年 | 43篇 |
1994年 | 60篇 |
1993年 | 36篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 28篇 |
1988年 | 27篇 |
1987年 | 30篇 |
1986年 | 27篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 24篇 |
1980年 | 16篇 |
1959年 | 35篇 |
1958年 | 58篇 |
1957年 | 87篇 |
1956年 | 45篇 |
1955年 | 75篇 |
1954年 | 67篇 |
1953年 | 17篇 |
1952年 | 14篇 |
1949年 | 10篇 |
排序方式: 共有1953条查询结果,搜索用时 15 毫秒
11.
The functional of B-L (Ia-equivalent)-positive (B-L+) adn -negative (B-L-) chicken peripheral blood lymphocytes (PBL) was studied in vitro and in vivo. The PBL were first stained in direct immunofluorescence tests with a fluorescein isothiocyanate-labelled anti-B-L alloantiserum and then separated by means of a fluorescence-activated cell sorter. In agreement with our previous findings, B-L- cells showed functional properties of T lymphocytes, responding to concanavalin A and phytohaemagglutinin-P in vitro and inducing a graft-versus-host (GVH) reaction when injected into allogeneic embryos. Sorted B-L+ gave no responses in any of these assays. Neither B-L+ nor B-L- cells, when tested alone, responded significantly to pokeweed mitogen, but mixtures of the two restored the responsiveness to that of the original unsorted suspension. Of the B-L+ PBL, 10% were T cells, which may account for the low GVH reactivity given by this population. 相似文献
12.
13.
Constrained optimization recently has been implemented in the LISREL software package, allowing formulation of parent-offspring transmission models in a simple and efficient manner. A reverse path model of parental transmission is described within the LISREL framework for application to twin and/or adoptive family data. The model incorporates genetic and environmental parameter constraints arising from assortative mating and cultural transmission. An illustration of the LISREL model is given using measures obtained from twins and parents involving fear of social criticism. 相似文献
14.
A. PIONA L. LA ROSA A. TINCANI D. FADEN† G. MAGRO‡ S. GRASSO‡ F. NICOLETTI G. BALESTRIERI P. L. MERONI 《Scandinavian journal of immunology》1995,41(5):427-432
In the present study we evaluated the effect of passive transfer of a mouse monoclonal (CAM) or a human polyclonal anti-cardiolipin IgG on pregnancy outcome in BALB/c mice. The mice were immunized through the tail vein immediately after mating with 10 μg of monoclonal or polyclonal anti-cardiolipin antibodies. Two other groups of mice were given a mouse irrelevant monoclonal antibody or normal human polyclonal IgG respectively, at the same dose. In mice immunized with monoclonal or polyclonal anti-cardiolipin antibody we observed a significant increase in the number of fetal resorptions and a significant reduction of the mean weights of the embryos and the placentas. In mice immunized with CAM we also found a significant decrease in the number of healthy pups, while mice infused with human aCL antibody expressed a significant reduction in the fecundity rate. The histological examination showed widespread thrombosis and necrosis in the placentas derived from the mice immunized with the anti-cardiolipin antibodies. The model supports a possible direct pathogenetic effect of anti-phospholipid antibodies in recurrent fetal loss and points out that thrombotic events at placental level can be instrumental in the pathogenesis of the obstetric complications. 相似文献
15.
Natalia Gimnez-Legarre Alba M. Santaliestra-Pasías Greet Cardon Rurik Imre Violeta Iotova Jemina Kivel Stavros Liatis Konstantinos Makrilakis Christina Mavrogianni Tatjana Milenkovic Anna Nnsi Tsvetalina Tankova Patrick Timpel Ruben Willems Yannis Manios Luis A. Moreno 《Nutrients》2021,13(3)
Positive influences of family members have been associated with a high probability of children’s daily breakfast consumption. Therefore, the aim of this study was to scrutinize the association of breakfast routines between mothers and their children. The baseline data of the Feel4Diabetes-study was obtained in 9760 children (49.05% boys)–mother pairs in six European countries. A parental self-reported questionnaire gauging the frequency of breakfast consumption and of breakfast´ foods and beverages consumption was used. Agreement in routines of mothers and their children’s breakfast consumption was analyzed in sex-specific crosstabs. The relationship of breakfast routine and food groups’ consumption between mothers and their children was assessed with analysis of covariance. The highest proportion of children who always consumed breakfast were those whose mothers always consumed it. Children consuming breakfast regularly had a higher intake of milk or unsweetened dairy products and all kind of cereal products (low fiber and whole-grain) than occasional breakfast consumers (p < 0.05). The strong similarity between mothers and children suggests a transfer of breakfast routine from mothers to their children, as a high proportion of children who usually consume breakfast were from mothers also consuming breakfast. All breakfast foods and beverages consumption frequencies were similar between children and their mothers. 相似文献
16.
目的:应用微乳液反应法制备磺胺嘧啶银均匀微晶,均匀制得的微晶的粒径大小约为2~4um,均匀微晶的结晶性好,纯度高。用均匀设计方法优化条件,制备的均匀的微晶平均粒径大小为2.09um,实验结果达到预测结果要求。结论:用微乳液反应法能获得磺胺嘧啶银均匀微晶。 相似文献
17.
微乳液反应法制备磺胺嘧啶银均匀微晶及其质量评价 总被引:1,自引:0,他引:1
目的:应用微乳液反应法制备磺胺嘧啶银均匀微晶,并评价其质量。方法:利用磺胺嘧啶钠微乳和硝酸银微乳混合后反应的方法,制备磺胺嘧啶银均匀微晶,用透射电镜观察其形态和大小,以X-射线衍射分析、红外光谱、核磁共振、差热分析等手段检测磺胺嘧啶银均匀微晶各种理化特性。结果:磺胺嘧啶银均匀微晶的粒径大小约为2~4μm,均匀微晶的结晶性好,纯度高。体外抑菌实验表明该品比市售磺胺嘧啶银具有更好的抑菌效果。结论:用微乳液反应法能获得磺胺嘧啶银均匀微晶。 相似文献
18.
Economic costs of functional dyspepsia 总被引:5,自引:0,他引:5
Dyspepsia is defined as chronic or recurrent symptoms believed to originate in the upper gastrointestinal tract. When routine investigation results in no identifiable explanation for those symptoms patients are labelled as having functional dyspepsia. In community-based surveys, approximately 30% of the otherwise apparently healthy population report dyspeptic symptoms and the majority are believed to have functional dyspepsia. Although only 1 in 4 or 5 patients make use of healthcare resources, this patient category is one of the largest in ambulatory care (1.6 to 5% of all consultations in general practice). The annual frequency of consultations for functional dyspepsia in Sweden has been estimated at 47 per 1000 population. In consequence of its high prevalence and associated absenteeism, the total costs of functional dyspepsia are considerable. In Sweden in 1981, the costs were estimated at $US55 000 per 1000 population ($US113 630 in 1991 dollars). The most cost-effective management strategy remains to be defined. Evidence is accumulating that the traditional 'wait-and-see' policy with initial empirical therapeutic trials without investigation may not be the most cost conserving strategy. 相似文献
19.
The involvement of the proliferating cell nuclear antigen (PCNA) in the
process of DNA repair induced by alkylating agents or by oxidative damage
was investigated in human quiescent fibroblasts by immunofluorescence and
flow cytometry. Transition from soluble to the DNA-bound form of PCNA, was
taken as the parameter to determine its involvement in repair DNA
synthesis. Treatment with the alkylating agents methylmethane sulfonate and
N-methyl-N'-nitro-N-nitrosoguanidine resulted in the rapid and
dose-dependent increase in the nuclear binding of PCNA. Similar results
were obtained with compounds such as hydrogen peroxide or tert-butyl
hydroperoxide, which are known to induce oxidative DNA damage. Tert-butyl
hydroperoxide may also generate malondialdehyde through a reaction of lipid
peroxidation. This mutagenic and carcinogenic product has been previously
shown to form adducts with DNA. Therefore, the possibility that tert-butyl
hydroperoxide could induce DNA damage through this pathway was investigated
by incubating cells directly in the presence of malondialdehyde. Such
treatment resulted in an increase in immunofluorescence associated with
nuclear-bound PCNA. The ability of oxidative and alkylating agents to
induce the nuclear binding of PCNA was also assessed in proliferating
cells. In these conditions, treatment with hydrogen peroxide or
methylmethane sulfonate, resulted in an increase in nuclear-bound PCNA in
the G1 and in the G2 + M compartments, but not in S phase. At longer times
after treatment, PCNA immunostaining was reduced to basal levels, while an
increase in nuclear binding of p21(waf1/cip1) protein was found in
concomitance with cell-cycle arrest. These results indicate that agents
inducing DNA base alterations in vivo, promote the nuclear binding of PCNA.
These lines of evidence support the role of a PCNA-dependent reaction in
the base excision repair system.
相似文献
20.
Hansen LA; Malarkey DE; Wilkinson JE; Rosenberg M; Woychik RE; Tennant RW 《Carcinogenesis》1998,19(10):1837-1845
We previously reported that papillomas can arise from the follicular
epithelium of v-Ha-ras transgenic TGxAC mice. Since the viable-yellow
mutation (A(vy)) of the mouse agouti gene which regulates coat color
pigmentation by acting within the micro-environment of the hair follicle
has been shown to function as a tumor promoter in the liver, we
hypothesized that it may also play a role in TGxAC skin tumorigenesis.
Endogenous agouti protein product was detected in the outer root sheath of
anagen hair follicles following plucking of the hair shaft, but not in the
interfollicular epithelium, in TGxAC mice on an FVB/N genetic background.
It was also detected in papillomas from these mice produced by
12-O-tetradecanoylphorbol-13-acetate (TPA) treatment or plucking.
Expression of the A(vy) allele in the v-Ha-ras transgenic TGxAC mouse line
results in an approximately 2-fold increase in papilloma development
compared with controls which did not carry the A(vy) allele following
twice-weekly treatment with 1.25, 2.5 or 5.0 microg TPA. In addition,
TPA-treated, papilloma-bearing F1 mice which carried the A(vy) allele, but
not F1 mice which did not carry the A(vy) allele, exhibited a syndrome of
humoral hypercalcemia mediated by parathyroid hormone-related protein
(PTHrP) that led to weight loss, hypercalcemia and hypophosphatemia. Thus,
we conclude that the A(vy) allele can influence the development of skin
tumors and PTHrP-mediated humoral hypercalcemia in v-Ha-ras transgenic
TGxAC mice.
相似文献