全文获取类型
收费全文 | 1178篇 |
免费 | 171篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 98篇 |
妇产科学 | 15篇 |
基础医学 | 124篇 |
口腔科学 | 46篇 |
临床医学 | 193篇 |
内科学 | 244篇 |
皮肤病学 | 16篇 |
神经病学 | 67篇 |
特种医学 | 164篇 |
外科学 | 172篇 |
综合类 | 37篇 |
预防医学 | 59篇 |
眼科学 | 2篇 |
药学 | 38篇 |
中国医学 | 5篇 |
肿瘤学 | 66篇 |
出版年
2022年 | 6篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 38篇 |
2017年 | 44篇 |
2016年 | 38篇 |
2015年 | 41篇 |
2014年 | 42篇 |
2013年 | 69篇 |
2012年 | 44篇 |
2011年 | 40篇 |
2010年 | 73篇 |
2009年 | 61篇 |
2008年 | 46篇 |
2007年 | 42篇 |
2006年 | 37篇 |
2005年 | 21篇 |
2004年 | 25篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 60篇 |
1997年 | 57篇 |
1996年 | 61篇 |
1995年 | 53篇 |
1994年 | 32篇 |
1993年 | 42篇 |
1992年 | 19篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 26篇 |
1987年 | 26篇 |
1986年 | 18篇 |
1985年 | 10篇 |
1984年 | 15篇 |
1983年 | 16篇 |
1982年 | 4篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1971年 | 2篇 |
1968年 | 4篇 |
排序方式: 共有1361条查询结果,搜索用时 31 毫秒
31.
Tissue-specific distribution of the Goodpasture antigen demonstrated by 2-D electrophoresis and Western blotting 总被引:2,自引:0,他引:2
The target of autoantibodies in Goodpasture's disease, the Goodpastureantigen has recently been characterized as the NC1 domain ofthe 3 chain of type IV collagen. In order to study the Goodpastureantigen in different organs, NC1 domains were isolated frombasement membranes (BM) of human glomeruli (GBM), tubules (TBM),alveoli (ABM), placenta (PBM) and aorta (VBM). NC1 preparationswere separated by 2-D electrophoresis, and silver stained orimmunoblotted to determine the subunit structure and antigenicityof different basement membranes. All basement membranes containedmonomeric components of MW 26 kDa and 24 kDa, and associateddimers, corresponding to the 2-D location of 1(IV) and cc2(IV)chains respectively. However, GBM, ABM, and to a lesser extentTBM possessed an extra set of monomeric components of MW 28kDa and associated dimers corresponding to the proposed locationof 3(IV) and 4(IV) chains. 2-D-separated polypeptides were Westernblotted with autoantibodies from patients with Goodpasture'sdisease, a monoclonal antibody to the Goodpasture antigen (P1)and a monoclonal antibody to the bovine 3(IV) chain. The predominantbinding of all these reagents was to cationic 28 kDa monomersof GBM, ABM and TBM, corresponding to the 3(IV) chain, althoughautoantibodies and P1 also bound to neutral 28 kDa monomers,corresponding to the 4(IV) chain. Autoantibodies bound weaklyto more neutral components of PBM and VBM, but neither monoclonalantibody bound to these basement membranes. This study suggeststhat there are two separate type IV collagen networks: one containingthe l(IV) and 2(IV) chains appears to be present in all basementmembranes, and the other containing the 3(IV) and 4(IV) chainshas a tissue specific distribution. The latter network bearingthe Goodpasture antigen is expressed in the basement membranesof both kidney and lung, the organs involved in Goodpasture'sdisease. 相似文献
32.
33.
Ultraviolet-light induced p53 mutational spectrum in yeast is indistinguishable from p53 mutations in human skin cancer 总被引:1,自引:2,他引:1
Inga A; Scott G; Monti P; Aprile A; Abbondandolo A; Burns PA; Fronza G 《Carcinogenesis》1998,19(5):741-746
Ultraviolet (UV) light has been associated with the development of human
non-melanoma skin cancers (NMSC). Such cancers often exhibit mutations in
the p53 tumour suppressor gene. In order to determine the UV-induced p53
mutation spectrum, a yeast expression vector that harbours a human
wild-type p53 cDNA was UV-irradiated in vitro and transfected into a yeast
strain that contained the ADE2 gene regulated by a p53-responsive promoter.
Forty-five mutant clones contained 51 mutations. Seven mutations were
tandem base pair substitutions, four of which being CC-->TT, hallmark
mutations of UV mutagenesis. Eighty percent (41/51) of the mutations were
single or non-tandem base pair substitutions, the majority of which (27/41)
were C-->T transitions. Ninety-five percent of such mutations occurred
at dipyrimidine sites. Through a rigorous statistical test, the UV-induced
p53 mutation spectrum appears to differ significantly (P < 0.008) from
the one induced by the antineoplastic drug
chloroethyl-cyclohexyl-nitrosourea, and to be indistinguishable from the
one observed in NMSC (P = 0.4). These results demonstrate that the assay
allows the determination of carcinogen-specific p53 mutation fingerprints
and represents a new tool for molecular epidemiology.
相似文献
34.
35.
Comparison of Bilateral vs. Staged Unilateral Deep Brain Stimulation (DBS) in Parkinson's Disease in Patients Under 70 Years of Age
下载免费PDF全文
![点击此处可从《Neuromodulation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
36.
37.
Expression of fibrinogen receptors during activation and subsequent desensitization of human platelets by epinephrine 总被引:2,自引:0,他引:2
Epinephrine causes platelet aggregation and secretion by interacting with alpha 2-adrenergic receptors on the platelet surface. Platelet aggregation requires the binding of fibrinogen to a specific receptor on the membrane glycoprotein IIb-IIIa complex. Although the IIb-IIIa complex is identifiable on the surface of resting platelets, the fibrinogen receptor is expressed only after platelet activation. The current studies were designed to examine the effect of occupancy of platelet alpha 2-adrenergic receptors by epinephrine on the expression of fibrinogen receptors and on the aggregation of platelets. The ability of epinephrine to induce the expression of fibrinogen receptors was studied under two different conditions: acute stimulation (less than 1 min) and prolonged stimulation (50 to 90 min), the latter of which is associated with a reduction or "desensitization" of the platelet aggregation response. Expression of the fibrinogen receptor was monitored with 125I-fibrinogen as well as with 125I-PAC-1 (PAC-1), a monoclonal antibody that binds to the glycoprotein IIb-IIIa complex only after platelets are activated. Epinephrine caused an immediate increase in PAC-1 and fibrinogen binding that was dependent on occupancy of the alpha 2-receptor by epinephrine and on the presence of extracellular free Ca (KCa = 30 mumol/L). By itself, 1 mmol/L Mg was unable to support induction of the fibrinogen receptor by epinephrine. However, it did decrease the Ca requirement by about two orders of magnitude. Prolonged stimulation of unstirred platelets by epinephrine led to a 70% decrease in the aggregation response when the platelets were subsequently stirred. Despite their decreased aggregation response, desensitized platelets bound PAC-1 and fibrinogen normally, indicating that the loss of aggregation was not due simply to a decrease in fibrinogen receptor expression. Although desensitization was not affected by pretreatment of the platelets with aspirin, it was partially prevented when extracellular Ca was chelated by EDTA during the long incubation with epinephrine. These studies demonstrate that once platelet alpha 2-adrenergic receptors are occupied by epinephrine, extracellular Ca is involved in initiating the aggregation response by supporting the induction of the fibrinogen receptor and the binding of fibrinogen. Furthermore. Ca-dependent reactions subsequent to fibrinogen binding may be necessary for maximal platelet aggregation and are impaired when platelets become desensitized to epinephrine. 相似文献
38.
Glycoprotein Ib and glycoprotein IX are fully complexed in the intact platelet membrane 总被引:3,自引:6,他引:3
Two new murine monoclonal antibodies, AK 1 and SZ 1, reactive with the human platelet glycoprotein (GP) Ib-IX complex have been produced by the hybridoma technique. Both AK 1 and SZ 1 immunoprecipitated the GP Ib-IX complex from Triton X-100-solubilized, periodate-labeled platelets. With trypsinized, labeled platelets, AK 1, SZ 1, and FMC 25 (epitope on GP IX) immunoprecipitated a membrane-bound proteolytic fragment of the GP Ib-IX complex consisting of GP IX and an congruent to 25,000 mol wt remnant of the alpha-chain of GP lb disulfide-linked to the beta-subunit. Unexpectedly, although AK 1 and SZ 1 immunoprecipitated purified GP Ib-IX complex, neither antibody immunoprecipitated the individual components of this complex, GP Ib or GP IX. When GP Ib and GP IX were recombined, however, AK 1 and SZ 1 again immunoprecipitated the reformed complex, strongly suggesting that both antibodies were recognizing an epitope present only on the intact complex. Cross-blocking studies indicated that AK 1 and SZ 1 recognized a very similar or identical epitope that was proximal to the epitope for FMC 25. Both AK 1 and SZ 1 bound to a similar number of binding sites (congruent to 25,000) on intact platelets as monoclonal antibodies directed against either GP lb or GP IX. The combined data suggests that GP lb and GP IX are fully complexed in the intact platelet membrane. 相似文献
39.
40.
AF Jorm H Christensen AS Henderson PA Jacomb AE Korten A Mackinnon 《Age and ageing》1996,25(2):126-129
Formal assessment of cognitive decline with cognitive tests can be difficult, requiring either two measurement points or a comparison of 'hold' with 'don't hold' tests. Informant-based assessment provides an alternative approach because informants can adopt a longitudinal perspective and directly rate cognitive change. A study was carried out to assess the validity of informant ratings collected by means of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). A community sample of 500 subjects aged 74 or over underwent four cognitive tests on two occasions 3½ years apart. On the second occasion, informants filled out the IQCODE. Subjects rated as having moderate or severe decline were found to have greater change on the cognitive tests. These findings support the validity of informant ratings of cognitive decline. 相似文献