全文获取类型
收费全文 | 335篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
355篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2018年 | 3篇 |
2016年 | 2篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 8篇 |
2007年 | 14篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 13篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1933年 | 2篇 |
1905年 | 2篇 |
排序方式: 共有355条查询结果,搜索用时 15 毫秒
41.
The purpose of the study was to determine the influence of energy status on metabolic and endocrine measures, follicular development, and the quality of oocytes obtained from cows during early and mid-lactation (ML). We selected Holstein cows at calving to be assigned to the early lactation (EL) group (n = 8), while we assigned cows at about day 90 postpartum to the ML group (n = 7). We obtained blood samples twice weekly from 4 weeks before aspiration to the aspiration periods for metabolite and hormone determinations. We performed ultrasound-guided transvaginal follicular aspiration (TVFA) twice weekly on all cows for a 10-week period. We obtained follicular fluid from the largest follicle > 10 mm in diameter for hormone determinations. We analyzed data by ANOVA, using the general linear model (GLM) procedures. Energy balance was positive (2.43 +/- 0.32 Mcal/kg) for ML cows and negative (-1.55 +/- 0.33 Mcal/kg) for EL cows. Serum progesterone (P4) for ML cows decreased rapidly from the first aspiration session (2.7 +/- 0.1 ng/ml) and reached a nadir at Week 8 (0.33 +/- 0.1 ng/ml), while follicular fluid P4 increased from 0.9 +/- 0.5 to 5.6 +/- 0.05 ng/ml. Serum and follicular fluid P4 remained relatively constant over the entire aspiration period for EL cows. Follicular fluid insulin-like growth factor I (TGF-I) concentrations increased linearly for EL and ML cows, but the increase was more rapid (159 +/- 36 to 200 +/- 36 ng/ml) for ML cows than for EL cows (145 +/- 36 to 164 +/- 36 ng/ml). Serum IGF-I followed the same pattern for ML cows but declined for EL cows. Early lactation cows experienced a rapid decrease in serum nonesterified fatty acids (NEFA; 0.32 +/- 0.2 to 0.22 +/- 0.2 meq/l), while serum NEFA concentrations were relatively stable (0.19 +/- 0.2 to 0.22 +/- 0.2 meq/l) for ML cows over the aspiration period. The number of follicles obtained from the twice weekly aspiration sessions increased linearly for both EL and ML cows (P < 0.05) over the 10-week period. However, the number of follicles increased from 14.2 +/- 0.5 (Day 119) to 18.1 +/- 0.5 (Day 190) in the ML cows, compared to the changes from 14.9 +/- 0.3 (Day 32) to 15.7 +/- 0.5 (Day 90) for the EL cows. These results indicate that cows are physiologically under more production stress during EL, but increasing follicular fluid and serum IGF-I throughout ML may reflect potential differences in follicle and oocyte measures, compared to cows in EL. 相似文献
42.
Kartchner Caverns in Benson, AZ, was opened for tourism in 1999 after a careful development protocol that was designed to
maintain predevelopment conditions. As a part of an ongoing effort to determine the impact of humans on this limestone cave,
samples were collected from cave rock surfaces along the cave trail traveled daily by tour groups (200,000 visitors year–1) and compared to samples taken from areas designated as having medium (30–40 visitors year–1) and low (2–3 visitors year–1) levels of human exposure. Samples were also taken from fiberglass moldings installed during cave development. Culturable
bacteria were recovered from these samples and 90 unique isolates were identified by using 16S rRNA polymerase chain reaction
and sequencing. Diversity generally decreased as human impact increased leading to the isolation of 32, 27, and 22 strains
from the low, medium, and high impact areas, respectively. The degree of human impact was also reflected in the phylogeny
of the isolates recovered. Although most isolates fell into one of three phyla: Actinobacteria, Firmicutes, or Proteobacteria,
the Proteobacteria were most abundant along the cave trail (77% of the isolates), while Firmicutes predominated in the low
(66%) and medium (52%) impact areas. Although the abundance of Proteobacteria along the cave trail seems to include microbes
of environmental rather than of anthropogenic origin, it is likely that their presence is a consequence of increased organic
matter availability due to lint and other organics brought in by cave visitors. Monitoring of the cave is still in progress
to determine whether these bacterial community changes may impact the future development of cave formations. 相似文献
43.
Kowalchick JE Leiting B Pryor KD Marsilio F Wu JK He H Lyons KA Eiermann GJ Petrov A Scapin G Patel RA Thornberry NA Weber AE Kim D 《Bioorganic & medicinal chemistry letters》2007,17(21):5934-5939
Various beta-amino amides containing triazolopiperazine heterocycles have been prepared and evaluated as potent, selective, orally active dipeptidyl peptidase IV (DPP-4) inhibitors. These compounds display excellent oral bioavailability and good overall pharmacokinetic profiles in preclinical species. Moreover, in vivo efficacy in an oral glucose tolerance test in lean mice is demonstrated. 相似文献
44.
Lysosomes: fusion and function 总被引:7,自引:0,他引:7
Lysosomes are dynamic organelles that receive and degrade macromolecules from the secretory, endocytic, autophagic and phagocytic membrane-trafficking pathways. Live-cell imaging has shown that fusion with lysosomes occurs by both transient and full fusion events, and yeast genetics and mammalian cell-free systems have identified much of the protein machinery that coordinates these fusion events. Many pathogens that hijack the endocytic pathways to enter cells have evolved mechanisms to avoid being degraded by the lysosome. However, the function of lysosomes is not restricted to protein degradation: they also fuse with the plasma membrane during cell injury, as well as having more specialized secretory functions in some cell types. 相似文献
45.
46.
Anna Schwendeman Denis O. Sviridov Wenmin Yuan Yanhong Guo Emily E. Morin Yue Yuan John Stonik Lita Freeman Alice Ossoli Seth Thacker Salena Killion Milton Pryor Y. Eugene Chen Scott Turner Alan T. Remaley 《Journal of lipid research》2015,56(9):1727-1737
The goal of this study was to understand how the reconstituted HDL (rHDL) phospholipid (PL) composition affects its cholesterol efflux and anti-inflammatory properties. An ApoA-I mimetic peptide, 5A, was combined with either SM or POPC. Both lipid formulations exhibited similar in vitro cholesterol efflux by ABCA1, but 5A-SM exhibited higher ABCG1- and SR-BI-mediated efflux relative to 5A-POPC (P < 0.05). Injection of both rHDLs in rats resulted in mobilization of plasma cholesterol, although the relative potency was 3-fold higher for the same doses of 5A-SM than for 5A-POPC. Formation of preβ HDL was observed following incubation of rHDLs with both human and rat plasma in vitro, with 5A-SM inducing a higher extent of preβ formation relative to 5A-POPC. Both rHDLs exhibited anti-inflammatory properties, but 5A-SM showed higher inhibition of TNF-α, IL-6, and IL-1β release than did 5A-POPC (P < 0.05). Both 5A-SM and 5A-POPC showed reduction in total plaque area in ApoE−/− mice, but only 5A-SM showed a statistically significant reduction over placebo control and baseline (P < 0.01). The type of PL used to reconstitute peptide has significant influence on rHDL’s anti-inflammatory and anti-atherosclerosis properties. 相似文献
47.
Báez-Flores ME Troncoso-Rojas R Osuna MA Domínguez MR Pryor B Tiznado-Hernández ME 《Microbiological research》2011,166(7):566-577
The molecular mechanism of the fungal tolerance phenotype to fungicides is not completely understood. This knowledge would allow for the development of environmentally friendly strategies for the control of fungal infection. With the goal of determining genes induced by 2p-ITC, a forward suppressive subtractive hybridization was performed using cDNAs from ITC-treated Alternaria alternata as a “tester” and from untreated fungus as a “driver.” Using this approach, a library containing 102 ESTs was generated that resulted in 50 sequences after sequence assembly (17 contigs and 33 singletons). Blastx analysis revealed that 38% and 40% of the sequences showed significant similarity with known and hypothetical proteins, respectively, whereas 18% were not similar to known genes. These last sequences could represent novel genes that play an unknown role in the molecular responses of fungi during adaptation to 2p-ITC. Clones similar to opsins, ABC transporters, calmodulin, ATPases and SNOG proteins were identified. Using real-time RT-PCR analysis, significant inductions of an ABC transporter and a Ca++ ATPase during 2p-ITC treatment were discovered. These results suggest that the fungal resistance phenotype to 2p-ITC involves calcium ions and 2p-ITC efflux via an ABC transporter. 相似文献
48.
49.
Frank R. Chen Theodore Quan Joseph E. Manzi Alex Gu Chapman Wei Sean Tabaie Marc Chodos Cary B. Chapman Kane O. Pryor Jiabin Liu 《The Iowa orthopaedic journal》2022,42(1):113
BackgroundTotal ankle arthroplasty (TAA) is performed for ankle arthritis and there has been interest investigating which anesthetic method is the best choice in order to optimize perioperative outcomes. In this study, we compared postoperative complications after TAA for patients receiving either 1) general anesthesia alone or 2) general anesthesia plus regional anesthesia.MethodsPatients undergoing primary TAA from 2007 to 2018 were identified in a national database. Patients were stratified into 2 cohorts: general anesthesia and general anesthesia combined with regional anesthesia. In this analysis, 30-day wound, cardiac, pulmonary, renal, thromboembolic, and sepsis complications, as well mortality, postoperative transfusion, urinary tract infection, extended length of stay, and reoperation were assessed. Bivariate analyses and multivariable logistical regression were performed.ResultsOf 1,084 total patients undergoing TAA, 878 patients (81.0%) had general anesthesia and 206 (19.0%) had general anesthesia combined with regional anesthesia. Following adjustment, there were no increased risk of postoperative complications in the combined general and regional anesthesia group compared to those who only underwent general anesthesia.ConclusionCompared to general anesthesia alone, the addition of regional anesthesia to general anesthesia for TAA is not associated with increased risk of complications in the perioperative period. Level of Evidence: III 相似文献
50.
JG Hansen W Gao J Dupuis GT O’Connor W Tang M Kowgier A Sood SA Gharib LJ Palmer M Fornage SR Heckbert BM Psaty SL Booth SUNLIGHT Consortium Patricia A Cassano 《Respiratory research》2015,16(1)