全文获取类型
收费全文 | 848篇 |
免费 | 44篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 53篇 |
妇产科学 | 4篇 |
基础医学 | 76篇 |
口腔科学 | 13篇 |
临床医学 | 112篇 |
内科学 | 256篇 |
皮肤病学 | 7篇 |
神经病学 | 20篇 |
特种医学 | 149篇 |
外科学 | 35篇 |
综合类 | 33篇 |
一般理论 | 2篇 |
预防医学 | 59篇 |
眼科学 | 3篇 |
药学 | 34篇 |
肿瘤学 | 34篇 |
出版年
2022年 | 1篇 |
2021年 | 6篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 20篇 |
2017年 | 12篇 |
2016年 | 6篇 |
2015年 | 14篇 |
2014年 | 25篇 |
2013年 | 31篇 |
2012年 | 18篇 |
2011年 | 28篇 |
2010年 | 40篇 |
2009年 | 26篇 |
2008年 | 20篇 |
2007年 | 16篇 |
2006年 | 21篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 29篇 |
2002年 | 16篇 |
2001年 | 24篇 |
2000年 | 30篇 |
1999年 | 16篇 |
1998年 | 37篇 |
1997年 | 29篇 |
1996年 | 26篇 |
1995年 | 26篇 |
1994年 | 28篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 21篇 |
1989年 | 26篇 |
1988年 | 25篇 |
1987年 | 17篇 |
1986年 | 17篇 |
1985年 | 24篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 8篇 |
1973年 | 1篇 |
1966年 | 3篇 |
排序方式: 共有894条查询结果,搜索用时 15 毫秒
1.
M. A. Schattner J. R. Geffner M. A. Isturiz M. A. Lazzari 《British journal of pharmacology》1990,101(2):253-256
1. The effect of unstimulated human polymorphonuclear leukocytes (PMNs) on platelet activation was examined. 2. Human platelet aggregation and adenosine 5'-triphosphate (ATP) release induced by collagen (1-2 micrograms ml-1); thrombin (0.01-0.02 u ml-1) or arachidonic acid (AA) (0.1-0.2 mM) were markedly inhibited when conducted in the presence of unstimulated PMNs. 3. Platelet inhibition induced by PMNs was dependent on the number of PMNs and on the incubation time of the mixed cell suspension. 4. Platelet inhibition was not reversed in time when PMNs were depleted from the mixed-cell suspension. 5. PMN-mediated platelet-inhibition was not mediated by AA metabolites, oxygen reactive intermediates, nitric oxide or proteases. 6. The factor(s) accounting for the platelet inhibition mediated by PMNs are not yet characterized. 相似文献
2.
Perforated colorectal neoplasms: correlation of clinical, contrast enema, and CT examinations 总被引:2,自引:0,他引:2
Hulnick DH; Megibow AJ; Balthazar EJ; Gordon RB; Surapenini R; Bosniak MA 《Radiology》1987,164(3):611-615
Results of clinical, contrast enema (CE), and computed tomographic (CT) examinations in 39 patients with perforated colorectal neoplasms were retrospectively reviewed. Twenty patients were toxemic at initial presentation, but in only four patients was the diagnosis of perforated colorectal neoplasm initially suspected clinically. CE study was performed in 22 patients and enabled the diagnosis of perforated neoplasm in 11 cases, neoplasm alone in eight, and neither neoplasm nor perforation in three. CT was performed in 38 patients and enabled the diagnosis of perforated neoplasm in 36; pericolic phlegmon but no mass lesion was evident in two. In 16 patients, CT also demonstrated metastatic disease. Because of its reliability in establishing the diagnosis and staging the extent of the inflammatory and neoplastic disease, CT is indicated in cases of suspected or proved perforated colorectal neoplasm and in cases in which CE study findings are indeterminate or suggestive of perforated neoplasm. 相似文献
3.
4.
5.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献
6.
7.
A Schattner D Duggan Y Naparstek R S Schwartz 《Clinical immunology and immunopathology》1986,38(3):327-336
Interferon (IFN) has extensive immunoregulatory effects but its role in systemic lupus erythematosus (SLE) remains obscure. The observations that a high proportion of patients with active SLE have increased IFN levels in their sera, and that IFN injected to lupus-prone mice aggrevates their disease, led us to examine the effects of IFN on the production of 16/6--a high frequency idiotype of monoclonal anti-DNA antibodies produced by human-human hybridomas derived from SLE patients. Peripheral blood mononuclear cells (PBMC) of healthy donors or of patients with SLE were incubated with IFN and pokeweed mitogen (PWM). Seven-day supernatants were assayed for total IgM, for IgM with 16/6 idiotype, and for IgM anti-DNA activity. PWM-stimulated PBMC of all healthy donors examined produced the 16/6 idiotype (mean 2.5 ng/ml). A significant increase of 16/6 in normals (above the level with PWM alone) was noted with 10-100 u/ml of IFN-alpha but not with 500 u/ml. In 3/10 normals the addition of IFN-alpha resulted in detectable anti-DNA activity. The IFN-induced increase in 16/6 idiotype was significantly more than the increase in IgM (335% vs 47% above baseline, with 10 u/ml of IFN). These effects of IFN could not be demonstrated in the absence of PWM nor in T-cell-depleted preparations. Recombinant IFN-gamma had no augmenting effect on 16/6 production. Three SLE patients in remission had elevated levels of 16/6 in their PBMC supernatant (15-200 ng/ml) which could not be further augmented by IFN. Thus, we have demonstrated the potential of PWM-stimulated normal lymphocytes to generate a "lupus" idiotype and shown that production of this idiotype requires T cells and is preferentially enhanced by IFN-alpha. Further studies of the effects of IFN on the expression of anti-DNA antibodies may clarify a postulated role of IFN in autoimmune diseases. 相似文献
8.
9.
Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
10.
The Bioperl toolkit: Perl modules for the life sciences 总被引:36,自引:4,他引:36
Stajich JE Block D Boulez K Brenner SE Chervitz SA Dagdigian C Fuellen G Gilbert JG Korf I Lapp H Lehväslaiho H Matsalla C Mungall CJ Osborne BI Pocock MR Schattner P Senger M Stein LD Stupka E Wilkinson MD Birney E 《Genome research》2002,12(10):1611-1618
The Bioperl project is an international open-source collaboration of biologists, bioinformaticians, and computer scientists that has evolved over the past 7 yr into the most comprehensive library of Perl modules available for managing and manipulating life-science information. Bioperl provides an easy-to-use, stable, and consistent programming interface for bioinformatics application programmers. The Bioperl modules have been successfully and repeatedly used to reduce otherwise complex tasks to only a few lines of code. The Bioperl object model has been proven to be flexible enough to support enterprise-level applications such as EnsEMBL, while maintaining an easy learning curve for novice Perl programmers. Bioperl is capable of executing analyses and processing results from programs such as BLAST, ClustalW, or the EMBOSS suite. Interoperation with modules written in Python and Java is supported through the evolving BioCORBA bridge. Bioperl provides access to data stores such as GenBank and SwissProt via a flexible series of sequence input/output modules, and to the emerging common sequence data storage format of the Open Bioinformatics Database Access project. This study describes the overall architecture of the toolkit, the problem domains that it addresses, and gives specific examples of how the toolkit can be used to solve common life-sciences problems. We conclude with a discussion of how the open-source nature of the project has contributed to the development effort. 相似文献