全文获取类型
收费全文 | 1132篇 |
免费 | 43篇 |
国内免费 | 1篇 |
专业分类
1176篇 |
出版年
2023年 | 8篇 |
2022年 | 21篇 |
2021年 | 32篇 |
2020年 | 22篇 |
2019年 | 23篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 68篇 |
2014年 | 50篇 |
2013年 | 78篇 |
2012年 | 125篇 |
2011年 | 104篇 |
2010年 | 45篇 |
2009年 | 59篇 |
2008年 | 76篇 |
2007年 | 71篇 |
2006年 | 54篇 |
2005年 | 55篇 |
2004年 | 65篇 |
2003年 | 46篇 |
2002年 | 42篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1176条查询结果,搜索用时 17 毫秒
31.
Thermal requirements (lower temperature threshold and thermal constant) for the development of each developmental stage of the predator Harmonia axyridis (Pallas) were studied on Aphis fabae Scopoli and Dysaphis crataegi (Kaltenbach) under controlled laboratory conditions. The effect of temperature (15, 20, 25, and 30°C) and prey species was examined on pre-imaginal developmental duration and life cycle (pre-oviposition period included) of the predator. Our results suggest comparable thermal requirements for the development of H. axyridis on the particular prey and when compared with other aphid species. The total preimaginal development of H. axyridis, at 15, 20, and 30°C, and its life cycle, at 15 and 30°C, are shorter on D. crataegi than on A. fabae. 相似文献
32.
Alexandra V. Stavropoulou Florentia Fostira Maroulio Pertesi Marianthi Tsitlaidou Gerassimos E. Voutsinas Olga Triantafyllidou Aristotelis Bamias Meletios A. Dimopoulos Eleni Timotheadou Dimitrios Pectasides Christos Christodoulou George Klouvas Christos Papadimitriou Thomas Makatsoris George Pentheroudakis Gerasimos Aravantinos Vassilis Karydakis Drakoulis Yannoukakos George Fountzilas Irene Konstantopoulou 《PloS one》2013,8(3)
Germline mutations in the BRCA1 and BRCA2 genes contribute to approximately 18% of hereditary ovarian cancers conferring an estimated lifetime risk from 15% to 50%. A variable incidence of mutations has been reported for these genes in ovarian cancer cases from different populations. In Greece, six mutations in BRCA1 account for 63% of all mutations detected in both BRCA1 and BRCA2 genes. This study aimed to determine the prevalence of BRCA1 mutations in a Greek cohort of 106 familial ovarian cancer patients that had strong family history or metachronous breast cancer and 592 sporadic ovarian cancer cases. All 698 patients were screened for the six recurrent Greek mutations (including founder mutations c.5266dupC, p.G1738R and the three large deletions of exon 20, exons 23–24 and exon 24). In familial cases, the BRCA1 gene was consequently screened for exons 5, 11, 12, 20, 21, 22, 23, 24. A deleterious BRCA1 mutation was found in 43/106 (40.6%) of familial cancer cases and in 27/592 (4.6%) of sporadic cases. The variant of unknown clinical significance p.V1833M was identified in 9/698 patients (1.3%). The majority of BRCA1 carriers (71.2%) presented a high-grade serous phenotype. Identifying a mutation in the BRCA1 gene among breast and/or ovarian cancer families is important, as it enables carriers to take preventive measures. All ovarian cancer patients with a serous phenotype should be considered for genetic testing. Further studies are warranted to determine the prevalence of mutations in the rest of the BRCA1 gene, in the BRCA2 gene, and other novel predisposing genes for breast and ovarian cancer. 相似文献
33.
Lindstrom S Schumacher F Siddiq A Travis RC Campa D Berndt SI Diver WR Severi G Allen N Andriole G Bueno-de-Mesquita B Chanock SJ Crawford D Gaziano JM Giles GG Giovannucci E Guo C Haiman CA Hayes RB Halkjaer J Hunter DJ Johansson M Kaaks R Kolonel LN Navarro C Riboli E Sacerdote C Stampfer M Stram DO Thun MJ Trichopoulos D Virtamo J Weinstein SJ Yeager M Henderson B Ma J Le Marchand L Albanes D Kraft P 《PloS one》2011,6(2):e17142
Genome-wide association studies (GWAS) have identified multiple single nucleotide polymorphisms (SNPs) associated with prostate cancer risk. However, whether these associations can be consistently replicated, vary with disease aggressiveness (tumor stage and grade) and/or interact with non-genetic potential risk factors or other SNPs is unknown. We therefore genotyped 39 SNPs from regions identified by several prostate cancer GWAS in 10,501 prostate cancer cases and 10,831 controls from the NCI Breast and Prostate Cancer Cohort Consortium (BPC3). We replicated 36 out of 39 SNPs (P-values ranging from 0.01 to 10−28). Two SNPs located near KLK3 associated with PSA levels showed differential association with Gleason grade (rs2735839, P = 0.0001 and rs266849, P = 0.0004; case-only test), where the alleles associated with decreasing PSA levels were inversely associated with low-grade (as defined by Gleason grade <8) tumors but positively associated with high-grade tumors. No other SNP showed differential associations according to disease stage or grade. We observed no effect modification by SNP for association with age at diagnosis, family history of prostate cancer, diabetes, BMI, height, smoking or alcohol intake. Moreover, we found no evidence of pair-wise SNP-SNP interactions. While these SNPs represent new independent risk factors for prostate cancer, we saw little evidence for effect modification by other SNPs or by the environmental factors examined. 相似文献
34.
35.
Rucha Karnik Christopher Grefen Robert Bayne Annegret Honsbein Tim K?hler Dimitrios Kioumourtzoglou Mary Williams Nia J. Bryant Michael R. Blatt 《The Plant cell》2013,25(4):1368-1382
The Arabidopsis thaliana Qa-SNARE SYP121 (=SYR1/PEN1) drives vesicle traffic at the plasma membrane of cells throughout the vegetative plant. It facilitates responses to drought, to the water stress hormone abscisic acid, and to pathogen attack, and it is essential for recovery from so-called programmed stomatal closure. How SYP121-mediated traffic is regulated is largely unknown, although it is thought to depend on formation of a fusion-competent SNARE core complex with the cognate partners VAMP721 and SNAP33. Like SYP121, the Arabidopsis Sec1/Munc18 protein SEC11 (=KEULE) is expressed throughout the vegetative plant. We find that SEC11 binds directly with SYP121 both in vitro and in vivo to affect secretory traffic. Binding occurs through two distinct modes, one requiring only SEC11 and SYP121 and the second dependent on assembly of a complex with VAMP721 and SNAP33. SEC11 competes dynamically for SYP121 binding with SNAP33 and VAMP721, and this competition is predicated by SEC11 association with the N terminus of SYP121. These and additional data are consistent with a model in which SYP121-mediated vesicle fusion is regulated by an unusual “handshaking” mechanism of concerted SEC11 debinding and rebinding. They also implicate one or more factors that alter or disrupt SEC11 association with the SYP121 N terminus as an early step initiating SNARE complex formation. 相似文献
36.
37.
Laoulakos DH Tsetsonis CH Michail AA Kaxira OS Papatheodorakis PH 《Plastic and reconstructive surgery》2003,112(1):121-5; discussion 126-8
Nine patients who presented with fingertip amputations were treated with the dorsal reverse adipofascial flap. The mean age of the patients was 41.3 years and the mean follow-up was 18 months. The flap described here was used only for amputations at the level of the nail fold, from approximately the lunula to the proximal nail matrix. This flap is based on the dorsal arterial branches that originate from the volar digital arteries just distal to the distal interphalangeal joint. The flap uses only the adipofascial tissue over the middle phalanx of the injured finger; it is turned over to cover the fingertip defect and then covered with a split-thickness skin graft. All flaps survived completely, and the patients continue to use their fingertips as before the amputation injury. This one-step operation is easily performed (even in the emergency department), makes no use of the adjacent digits, and provides a pleasing and stable cover for the fingertips. 相似文献
38.
Zgouras D Becker U Loitsch S Stein J 《Biochemical and biophysical research communications》2004,316(3):693-697
Recent studies have attested to the antiangiogenic effects of HDAC inhibitors on solid human tumors. The HDAC inhibitor butyrate has been reported to impair tumor-cell-induced angiogenesis. However, due to its poor bioavailability in vivo, the therapeutic use of butyrate is limited. On the other hand, valproic acid has inhibitory effects on carcinoma cells, is known to be well tolerated, and has an excellent bioavailability. We therefore set out to investigate whether the HDAC inhibitor valproic acid also impairs angiogenesis. Our findings indicate that valproic acid represses the relevant angiogenic factors VEGF and FGF in Caco-2 cells. Both, protein expression as well as mRNA levels of VEGF, were reduced to a similar degree. Suppression of ubiquitin-proteasome activity could be a possible reason for valproic acid effects on regulatory angiogenesis proteins. These results suggest that the HDAC inhibitor valproic acid could become a valuable new addition in the attempt to develop alternative therapeutic approaches in the treatment of colon carcinomas. 相似文献
39.
A long-range surface plasmon polariton variable optical attenuator based on available nematic liquid crystals and polymers is proposed and theoretically investigated. It is demonstrated that the electro-optic control of the nematic molecular orientation is capable of tuning the level of index asymmetry of an Au stripe waveguide and the key properties of the fundamental long-range plasmonic mode, such as modal profile and propagation losses. By proper structural design and material selection, plasmonic in-line intensity modulators are designed, which exhibit very low power consumption, extinction ratios in excess of 30 dB, and insertion losses as low as 1 dB for a device length in the millimeter range. Such active plasmonic elements are envisaged to be used in interchip photonics bus interconnects. 相似文献
40.