全文获取类型
收费全文 | 511篇 |
免费 | 22篇 |
国内免费 | 1篇 |
出版年
2023年 | 6篇 |
2022年 | 10篇 |
2021年 | 35篇 |
2020年 | 17篇 |
2019年 | 20篇 |
2018年 | 22篇 |
2017年 | 11篇 |
2016年 | 19篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 32篇 |
2011年 | 31篇 |
2010年 | 23篇 |
2009年 | 12篇 |
2008年 | 19篇 |
2007年 | 35篇 |
2006年 | 22篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 2篇 |
1961年 | 1篇 |
排序方式: 共有534条查询结果,搜索用时 328 毫秒
381.
T. Hilary Howells T. Khanam Louis Kreel C. Seymour B. Oliver J. A. H. Davies 《BMJ (Clinical research ed.)》1971,2(5761):558-560
This paper evaluates the use of metoclopramide (Maxolon) in emptying human stomach contents into the duodenum and beyond. A method of quantitative assessment of content by barium swallow radiography is used in the study, and the method is recommended as a diagnostic manoeuvre in patients presenting for emergency surgery in whom the stomach content is in doubt. Oral metoclopramide was found effective in emptying stomachs challenged by water load, and the intravenous route has been found effective in emptying semisolid contents in emergency clinical situations. A radiographic scan of the resting stomach was made on patients waiting for routine surgery who had received a variety of common premedication; it was shown that significant residues occur.We believe that metoclopramide deserves further investigation in order to exploit its potential in reducing the hazard of regurgitation and vomiting in patients requiring emergency anaesthesia and surgery. 相似文献
382.
The influence of three analogs of cyclic adenosine monophosphate (cAMP) and theophylline on growth of colon tumor cell lines HT 29, LIM 1215 and COLO 206F was assessed by serial estimates of cell number. Administration of theophylline or analog of cAMP 8-bromo cAMP (8-br-cAMP) to actively replicating cultures resulted in a decrease in cell number of each cell line. In contrast analogs of cAMP, dibutyryl cAMP (db-cAMP) and chlorophenylthio cAMP (cp-cAMP) caused an increase in cell number of each cell line. This variation between analogs makes it difficult to draw conclusions regarding the influence of cAMP on cell growth when analogs are used to mimic the biological role of cAMP. 相似文献
383.
Sabiha R Saba Amanda H Garces Linda C Clark John Soto William R Gower David L Vesely 《The journal of histochemistry and cytochemistry》2005,53(8):989-995
We recently found that four peptide hormones synthesized by the same gene completely inhibit the growth of human pancreatic adenocarcinomas in athymic mice. The present immunocytochemical investigation was designed to determine where in the adenocarcinomas these peptide hormones localize. Atrial natriuretic peptide, vessel dilator, long-acting natriuretic peptide, and kaliuretic peptide localized to the cytoplasm and nucleus of the human pancreatic adenocarcinomas, which is consistent with their ability to decrease DNA synthesis in the nucleus of this cancer. In this first investigation of where these peptide hormones with anticancer effects localize in any cancer, these peptide hormones also localized to the endothelium of capillaries and fibroblasts within these cancers. This is the first demonstration of growth-inhibiting peptide hormones localizing to the nucleus, where they inhibit DNA synthesis and may interact with growth-promoting hormones that localize there as the etiology of their ability to inhibit the growth of adenocarcinomas both in vitro and in vivo. 相似文献
384.
Four U4 RNA pseudogenes were isolated and characterized from a rat genomic bank. The four pseudogenes contained sequences completely homologous to U4 RNA from nucleotides 1 to 67 and had common truncated 3'-ends. Three of the four pseudogenes were flanked by 14 to 18 nucleotide-long direct repeats. The structural features of these four U4 RNA pseudogenes are consistent with the hypothesis that these pseudogenes arose by RNA self-primed complementary DNA synthesis and integration into the genome (Van Arsdell et al., Cell 26:11-17, 1981). 相似文献
385.
Emebet Adem Fitsumbirhan Tajebe Mulusew Getahun Amare Kiflie Ermias Diro Asrat Hailu Ziv Shkedy Bewketu Mengesha Tadele Mulaw Saba Atnafu Tekalign Deressa Biniam Mathewos Ebba Abate Manuel Modolell Markus Munder Ingrid Müller Yegnasew Takele Pascale Kropf 《PLoS neglected tropical diseases》2016,10(3)
One of the key immunological characteristics of active visceral leishmaniasis (VL) is a profound immunosuppression and impaired production of Interferon-γ (IFN-γ). However, recent studies from Bihar in India showed using a whole blood assay, that whole blood cells have maintained the capacity to produce IFN-γ. Here we tested the hypothesis that a population of low-density granulocytes (LDG) might contribute to T cell responses hyporesponsiveness via the release of arginase. Our results show that this population is affected by the anticoagulant used to collect blood: the frequency of LDGs is significantly lower when the blood is collected with heparin as compared to EDTA; however, the anticoagulant does not impact on the levels of arginase released. Next, we assessed the capacity of whole blood cells from patients with active VL to produce IFN-γ and IL-10 in response to antigen-specific and polyclonal activation. Our results show that whole blood cells produce low or levels below detection limit of IFN-γ and IL-10, however, after successful treatment of VL patients, these cells gradually regain their capacity to produce IFN-γ, but not IL-10, in response to activation. These results suggest that in contrast to VL patients from Bihar, India, whole blood cells from VL patients from Gondar, Ethiopia, have lost their ability to produce IFN-γ during active VL and that active disease is not associated with sustained levels of IL-10 production following stimulation. 相似文献
386.
387.
Tjeerd Barf Fredrik Lehmann Kristin Hammer Saba Haile Eva Axen Carmen Medina Jonas Uppenberg Stefan Svensson Lena Rondahl Thomas Lundbäck 《Bioorganic & medicinal chemistry letters》2009,19(6):1745-1748
Small molecule inhibitors of adipocyte fatty-acid binding protein (A-FABP) have gained renewed interest following the recent publication of pharmacologically beneficial effects of such inhibitors. Despite the potential utility of selective A-FABP inhibitors within the fields of metabolic disease, inflammation and atherosclerosis, there are few examples of useful A-FABP inhibitors in the public domain. Herein, we describe the optimization of N-benzyl-tetrahydrocarbazole derivatives through the use of co-crystal structure guided medicinal chemistry efforts. This led to the identification of a potent and selective class of A-FABP inhibitors as illustrated by N-benzyl-hexahydrocyclohepta[b]indole 30. 相似文献
388.
Grace K. Saba Oscar Schofield Joseph J. Torres Erica H. Ombres Deborah K. Steinberg 《PloS one》2012,7(12)
Ocean acidification has a wide-ranging potential for impacting the physiology and metabolism of zooplankton. Sufficiently elevated CO2 concentrations can alter internal acid-base balance, compromising homeostatic regulation and disrupting internal systems ranging from oxygen transport to ion balance. We assessed feeding and nutrient excretion rates in natural populations of the keystone species Euphausia superba (Antarctic krill) by conducting a CO2 perturbation experiment at ambient and elevated atmospheric CO2 levels in January 2011 along the West Antarctic Peninsula (WAP). Under elevated CO2 conditions (∼672 ppm), ingestion rates of krill averaged 78 µg C individual−1 d−1 and were 3.5 times higher than krill ingestion rates at ambient, present day CO2 concentrations. Additionally, rates of ammonium, phosphate, and dissolved organic carbon (DOC) excretion by krill were 1.5, 1.5, and 3.0 times higher, respectively, in the high CO2 treatment than at ambient CO2 concentrations. Excretion of urea, however, was ∼17% lower in the high CO2 treatment, suggesting differences in catabolic processes of krill between treatments. Activities of key metabolic enzymes, malate dehydrogenase (MDH) and lactate dehydrogenase (LDH), were consistently higher in the high CO2 treatment. The observed shifts in metabolism are consistent with increased physiological costs associated with regulating internal acid-base equilibria. This represents an additional stress that may hamper growth and reproduction, which would negatively impact an already declining krill population along the WAP. 相似文献
389.
William S. Pietrzak Saba N. Ali Deepika Chitturi Mahima Jacob Jennifer E. Woodell-May 《Cell and tissue banking》2011,12(2):81-88
Demineralization of allograft bone increases the bioavailability of matrix-associated bone morphogenetic proteins (BMPs),
rendering these grafts osteoinductive. While osteoinductivity is related to BMP content, little is known about how the demineralization
protocol, in particular, extended demineralization times, affects graft BMP levels. We characterized the BMP-7 content of
<710 μm bovine bone powder demineralized under various conditions. Using 1 g of bone per 50 ml of 0.125 N, 0.25 N, or 0.5 N
HCl, demineralization was performed at room temperature for 5 min to 24 h. Minimum residual calcium levels were obtained within
90 min and were <1 wt % using the 0.25 N and 0.5 N baths and 17 wt % using the 0.125 N bath. Measured peak BMP-7 levels were
also obtained within 90 min and were 161–165 ng g−1 using the 0.25 N and 0.5 N baths and 55.2 ng g−1 using the 0.125 N bath. This compares to 5.1 ng g−1 for undemineralized bone. Further acid bath exposure to 24 h resulted in BMP-7 decline to about 50% of the peak value, which
was significant. The BMP-7 half-life was estimated to be 26 h. It is likely that the decline was due to diffusion of BMP-7
from the bone matrix into the acid. These results suggest the importance of not over demineralizing bone grafts and should
stimulate further research that can be incorporated into the processing methodology followed by tissue banks. 相似文献
390.