全文获取类型
收费全文 | 181篇 |
免费 | 15篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 12篇 |
2011年 | 8篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 8篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1961年 | 2篇 |
1958年 | 2篇 |
1955年 | 2篇 |
1949年 | 1篇 |
1946年 | 2篇 |
1944年 | 1篇 |
1943年 | 3篇 |
1940年 | 3篇 |
1939年 | 1篇 |
1936年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
1933年 | 1篇 |
1931年 | 1篇 |
1930年 | 1篇 |
1929年 | 1篇 |
1928年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有197条查询结果,搜索用时 15 毫秒
1.
2.
In actual practice, the choice of anesthesia is more likely to be decided by the personal preference of the surgeon or anesthesiologist rather than by considerations of safety. Most gynecologists in the US and Canada, working in hospitals or surgicenters, choose general anesthesia becaused skilled anesthetists are available, and it is easier for them to operate if their patients are asleep. Most anesthesiologists prefer it that way also, since their services are being fully utilized. During residency training, gynecologists need the benefit of general anesthesia to learn surgical techniques. Because they learned that way, it is the course of least resistance for them to continue to favor general anesthesia. Thus hundreds of thousands of general anesthetics are given each year to suit the convenience and skills of the gynecologist. But minilaparotomy or laparoscopy may be performed with fewer potential complications under local anesthesia, provided the patient receives proper counseling and supportive care, and provided the gynecologist's surgical technique is gentle and precise. Unfortunately, most residency programs do not provide training in such techniques, so they are learned, if at all, during practice years. 相似文献
3.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
4.
5.
大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献
6.
7.
Theresa Townsend Vincent Segura Godfree Chigeza Teresa Penfield Anne Rae David Harvey Dianna Bowles Ian A. Graham 《PloS one》2013,8(4)
Artemisia annua is an important medicinal crop used for the production of the anti-malarial compound artemisinin. In order to assist in the production of affordable high quality artemisinin we have carried out an A. annua breeding programme aimed at improving artemisinin concentration and biomass. Here we report on a combining ability analysis of a diallel cross to identify robust parental lines for hybrid breeding. The parental lines were selected based on a range of phenotypic traits to encourage heterosis. The general combining ability (GCA) values for the diallel parental lines correlated to the positive alleles of quantitative trait loci (QTL) in the same parents indicating the presence of beneficial alleles that contribute to parental performance. Hybrids generated from crossing specific parental lines with good GCA were identified as having an increase in both artemisinin concentration and biomass when grown either in glasshouse or experimental field trials and compared to controls. This study demonstrates that combining ability as determined by a diallel cross can be used to identify elite parents for the production of improved A. annua hybrids. Furthermore, the selection of material for breeding using this approach was found to be consistent with our QTL-based molecular breeding approach. 相似文献
8.
9.
10.
Black AP Bhayani H Ryder CA Pugh MT Gardner-Medwin JM Southwood TR 《Arthritis research & therapy》2003,5(5):R277-R284
The aim of this research was to determine whether all memory T cells have the same propensity to migrate to the joint in patients
with juvenile idiopathic arthritis. Paired synovial fluid and peripheral blood mononuclear cell proliferative responses to
a panel of antigens were measured and the results correlated with a detailed set of laboratory and clinical data from 39 patients
with juvenile idiopathic arthritis. Two distinct patterns of proliferative response were found in the majority of patients:
a diverse pattern, in which synovial fluid responses were greater than peripheral blood responses for all antigens tested;
and a restricted pattern, in which peripheral blood responses to some antigens were more vigorous than those in the synovial
fluid compartment. The diverse pattern was generally found in patients with a high acute phase response, whereas patients
without elevated acute phase proteins were more likely to demonstrate a restricted pattern. We propose that an association
between the synovial fluid T cell repertoire and the acute phase response suggests that proinflammatory cytokines may influence
recruitment of memory T cells to an inflammatory site, independent of their antigen specificity. Additionally, increased responses
to enteric bacteria and the presence of αEβ7 T cells in synovial fluid may reflect accumulation of gut associated T cells
in the synovial compartment, even in the absence of an elevated acute phase response. This is the first report of an association
between the acute phase response and the T cell population recruited to an inflammatory site. 相似文献