全文获取类型
收费全文 | 1932篇 |
免费 | 0篇 |
学科分类
工业技术 | 1932篇 |
出版年
2010年 | 1篇 |
2007年 | 1篇 |
2005年 | 2篇 |
2003年 | 3篇 |
1999年 | 64篇 |
1998年 | 567篇 |
1997年 | 356篇 |
1996年 | 238篇 |
1995年 | 120篇 |
1994年 | 94篇 |
1993年 | 121篇 |
1992年 | 12篇 |
1991年 | 24篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 13篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 62篇 |
1976年 | 124篇 |
1975年 | 6篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1955年 | 2篇 |
1954年 | 1篇 |
排序方式: 共有1932条查询结果,搜索用时 0 毫秒
991.
Chromosomes from 20 patients were used to delineate the breakpoints of inverted duplications of chromosome 15 (inv dup[15]) that include the Prader-Willi syndrome/Angelman syndrome (PWS/AS) chromosomal region (15q11-q13). YAC and cosmid clones from 15q11-q14 were used for FISH analysis, to detect the presence or absence of material on each inv dup(15). We describe two types of inv dup(15): those that break between D15S12 and D15S24, near the distal boundary of the PWS/AS chromosomal region, and those that share a breakpoint immediately proximal to D15S1010. Among the latter group, no breakpoint heterogeneity could be detected with the available probes, and one YAC (810f11) showed a reduced signal on each inv dup(15), compared with that on normal chromosomes 15. The lack of breakpoint heterogeneity may be the result of a U-type exchange involving particular sequences on either homologous chromosomes or sister chromatids. Parent-of-origin studies revealed that, in all the cases analyzed, the inv dup(15) was maternal in origin. 相似文献
992.
The purpose of this study was to explore gender differences of medication use in a random sample of community-dwelling elderly subjects (N = 791). The average number of different medications in women (N = 578) was higher than in men (N = 213) (4.0 vs. 3.5, age corrected ratio 1.2, 95% confidence interval, 1.0-1.3). However, despite this relatively small difference in number of medications there was a major gender difference in the pattern of medications used. Compared to men, women had a higher use of benzodiazepines (risk ratio 1.7, 95% confidence interval, 1.3-2.3), diuretics (1.5, 1.1-2.0), nonsteroidal antiinflammatory agents (1.7, 1.2-2.3), and anti-depressants (2.5, 1.1-5.5), but a lower use of pulmonary (0.5, 0.3-0.9) and gout medications (0.2, 0.1-0.6). These gender differences in medication use can be explained by the fact that compared to men, women have a higher prevalence of non-lethal chronic conditions such as degenerative joint disease and hypertension. However, additional factors such as gender-specific differences in patient or physician behavior are likely to contribute to the observed differences in medication use as well. Overall, 36% of all women and 21% of all men were using benzodiazepines, with 42% of these subjects using long-acting compounds. Furthermore, 24% of all women and 15% of all men reported use of nonsteroidal antiinflammatory agents for which safer medication and non-medication alternatives would be available in many cases. Thus, women had a higher risk of inappropriate medication use than men. On the other hand, the finding that antidepressant use was 3% in men and 7% in women indicates that compared to women, men might be at increased risk for undertreatment of depression. Further causal evaluation of gender differences in both medication use and patient-physician interaction might contribute to detection and reduction of inappropriate drug use in older persons. 相似文献
993.
BACKGROUND: Experimental animal studies have shown that coronary stenting induces neointimal proliferation. However, the histopathological events after coronary stenting in humans have not been studied systematically. METHODS AND RESULTS: We investigated 11 stented coronary arteries (9 Palmaz-Schatz stents, 1 Wiktor stent, and 1 ACS Multi-Link stent) obtained from 11 patients who had died 2 days to 21 months after stenting. We focused on gross, histological, and immunohistochemical aspects of the repair processes. Two patients developed symptoms of restenosis. Serial sections were stained with antibodies against smooth muscle cells (SMCs), macrophages, and endothelial cells. At 9 and 12 days after stenting, the stent sites showed thrombus formation with early formation of neointima composed of abundant macrophages and alpha-actin-negative spindle cells. From 64 days on, all sites with stenting showed a distinct layer of neointima, albeit to varying degrees. In nonrestenotic lesions, neointimal thickening was markedly less than in restenotic lesions but without qualitative differences; the neointima contained macrophages but was composed predominantly of alpha-actin-positive SMCs. CONCLUSIONS: These observations strongly support the concept that neointimal proliferation in humans is a process of staged redifferentiation of SMCs, which may cause in-stent stenosis. Moreover, the exuberant neointimal proliferation with accumulation of macrophages and extensive neovascularization at sites of stent restenosis suggests a role for organization of mural thrombus. 相似文献
994.
HS Thompson ML Davies MJ Watts AE Mann FP Holding T O'Neill JT Beech SJ Thompson GD Leesman JT Ulrich 《Canadian Metallurgical Quarterly》1998,16(20):1993-1999
The regression of genital warts is believed to be a T-cell-mediated immune effect. We have sought to enhance the immunogenicity of a therapeutic vaccine for the treatment of genital warts with the use of the adjuvant monophosphoryl lipid A (MPL-immunostimulant), a detoxified form of the lipopolysaccharide (LPS) of Salmonella minnesota R595. The comparative immunogenicity and reactogenicity of a recombinant human papillomavirus type 6 (HPV6) L2E7 fusion protein in either aqueous, oil-in-water emulsions or Alhydrogel formulations containing MPL was evaluated. We conclude that the simple addition of MPL to the L2E7 fusion protein already adsorbed onto Alhydrogel preferentially enhances antigen specific in vitro T-cell proliferative responses, IFN gamma production and in vivo delayed type hypersensitivity responses without increasing its reactogenicity. 相似文献
995.
PJ Winsauer FH Rodriguez AE Cha JM Moerschbaecher 《Canadian Metallurgical Quarterly》1999,288(1):335-347
As a means of characterizing the role of 5-hydroxytryptamine (5-HT1A) receptors in learning, a full 5-HT1A receptor agonist, 8-hydroxy-dipropylaminotetralin (8-OH-DPAT), was administered both alone and in combination with two partial agonists (buspirone and 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide (NAN-190)) and a 5-HT1A receptor antagonist (p-MPPI) to rats responding under a multiple schedule of repeated acquisition and performance of response sequences. In addition, the effects of another 5-HT1A receptor agonist, (LY228729), were also studied under this same procedure. When administered alone, both 8-OH-DPAT (0.1-3. 2 mg/kg) and LY228729 (0.32-3.2 mg/kg) dose dependently decreased overall response rate and increased the percentage of errors in the acquisition and performance components. At the doses of each drug tested, both buspirone (0.32 or 1 mg/kg) and NAN-190 (1 or 3.2 mg/kg) also decreased overall response rate and increased the percentage of errors. However, the effects of these drugs differed across behavioral components and dependent measures. The effects of buspirone and NAN-190 on rate and accuracy were also different when they were administered in combination with 8-OH-DPAT. In contrast, p-MPPI (3.2 or 10 mg/kg) had little or no effect when administered alone and antagonized the effects of 8-OH-DPAT; shifting the dose-effect curves for both response rate and the percentage of errors in both components to the right. Taken together, these results indicate that complex behaviors in rats are sensitive to disruption by drugs with both full and partial 5-HT1A receptor agonist properties, and that the effects of partial 5-HT1A receptor agonists on learning may be different depending on their efficacy at pre- and postsynaptic 5-HT1A receptors. 相似文献
996.
AB van't Wout LJ Ran MD de Jong M Bakker R van Leeuwen DW Notermans AE Loeliger F de Wolf SA Danner P Reiss CA Boucher JM Lange H Schuitemaker 《Canadian Metallurgical Quarterly》1997,100(9):2325-2332
By studying changes in the clonal composition of HIV-1 populations during the first weeks of zidovudine (ZDV) treatment before the development of ZDV resistance-conferring mutations, we demonstrated previously a selective inhibition of nonsyncytium-inducing (NSI) HIV-1, even when present as coexisting population in individuals also harboring syncytium-inducing (SI) HIV-1. In this study, we observed the opposite in individuals receiving didanosine (ddI) treatment. In these individuals (n = 7) a median -0.98 log change (range -1.55-0.08) in infectious cellular SI load was observed, whereas the coexisting NSI load was only minimally affected (median -0.15 log, range -1.27-0.50; P = 0.03). The virus phenotype-dependent treatment responses were independent of the clonal composition of HIV-1 populations at baseline. Individuals treated with a combination of ZDV and ddI revealed an equal decline of both NSI and SI infectious cellular load (n = 4; NSI: median -1.55 log, range -2.19 to -1.45; SI: median -1.47 log, range -1.81 to -0.86; P = 0.56). To test the hypothesis that the previously reported optimal activation of ZDV and ddI in activated and resting T cells, respectively, in combination with the differential T cell tropism of NSI and SI HIV-1 is the basis for the observed virus phenotype specific efficacy of nucleoside analogs, we studied the effect of treatment with a protease inhibitor that does not require intracellular activation. Individuals receiving ritonavir (n = 4) indeed showed equal declines in NSI and SI infectious cellular load (NSI: median -2.37 log, range -2.59 to -2.16; SI: median -2.82 log, range -3.14 to -2.50; P = 0.25). Our data suggest HIV-1 phenotype as an additional parameter in the design of optimal treatment regimens. 相似文献
997.
AE Walters PB Myrdal S Pinsuwan AM Manka SH Yalkowsky 《Canadian Metallurgical Quarterly》1997,690(1-2):99-103
A solid-phase extraction (SPE) method has been developed for the isolation of melanotan II from rabbit urine. The proposed extraction method makes it possible to selectively isolate melanotan II without significant loss of the peptide. Standard curves obtained from high-performance liquid chromatographic (HPLC) analysis of spiked urine extracts are linear from 0.1 to 4.0 micrograms/ml. The analytical method is shown to be highly reproducible, giving a relative standard deviation of less than 5% for both between-day and same-day analyses. The accuracy of the method obtained from standard plots ranges from -3.3 to 3.1%. 相似文献
998.
RD Ennis AE Katz GM de Vries DF Heitjan KM O'Toole M Rubin R Buttyan MC Benson PB Schiff 《Canadian Metallurgical Quarterly》1997,79(12):2402-2408
999.
1000.
RD Harrington CG Lewis J Aslanzadeh P Stelmach AE Woolfrey 《Canadian Metallurgical Quarterly》1996,34(7):1821-1824
Oerskovia spp. are gram-positive, Nocardia-like bacilli which inhabit the soil and rarely cause human infections. Previously reported cases of Oerskovia infection have been characterized by a nonaggressive course and an association with foreign bodies. We report the first case of a patient with a prosthetic joint infection due to Oerskovia xanthineolytica. Our patient presented with a prolonged, indolent course and was thought to have aseptic loosening of his prosthesis until the time of surgery. He was cured of his infection by removal of the prosthesis, antibiotic therapy, and delayed reimplantation. Review of the previous 10 reported cases of Oerskovia infection in humans supports the recommendation that foreign-body-associated infections should be treated with a strategy that includes removal of the foreign material. 相似文献