全文获取类型
收费全文 | 1469篇 |
免费 | 118篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 44篇 |
妇产科学 | 28篇 |
基础医学 | 176篇 |
口腔科学 | 53篇 |
临床医学 | 188篇 |
内科学 | 339篇 |
皮肤病学 | 22篇 |
神经病学 | 85篇 |
特种医学 | 132篇 |
外科学 | 137篇 |
综合类 | 22篇 |
预防医学 | 118篇 |
眼科学 | 57篇 |
药学 | 96篇 |
中国医学 | 13篇 |
肿瘤学 | 85篇 |
出版年
2024年 | 3篇 |
2023年 | 21篇 |
2022年 | 49篇 |
2021年 | 63篇 |
2020年 | 47篇 |
2019年 | 61篇 |
2018年 | 59篇 |
2017年 | 24篇 |
2016年 | 45篇 |
2015年 | 45篇 |
2014年 | 74篇 |
2013年 | 86篇 |
2012年 | 99篇 |
2011年 | 101篇 |
2010年 | 70篇 |
2009年 | 58篇 |
2008年 | 75篇 |
2007年 | 79篇 |
2006年 | 71篇 |
2005年 | 41篇 |
2004年 | 38篇 |
2003年 | 46篇 |
2002年 | 29篇 |
2001年 | 25篇 |
2000年 | 25篇 |
1999年 | 26篇 |
1998年 | 26篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1964年 | 1篇 |
排序方式: 共有1607条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
S. Ngo N. Barber A. Jacklin P. Clark 《The International journal of pharmacy practice》1992,1(4):193-197
The time taken in hospital pharmacies to produce labels for individual patients' medication was measured, and factors affecting the labelling process investigated. Labelling time was measured by direct observation using a stopclock at randomly chosen semi-stratified time periods. Four combinations of major London hospitals and computer systems were studied. The time to produce 2,167 labels was measured and 59 operators were observed. There were significant differences in average labelling time between the studied hospitals/systems (16.6 to 39.3 seconds per label). Operators' experience with their system and the occurrence of interruptions were found to affect labelling significantly (P<0.0001 in both cases). There was an overall trend for labelling time to decrease with increasing experience (P<0.0001), and interruptions added 11 to 12 seconds on average. Operator experience also affected the rate and duration of interruptions, which subsequently affected labelling time. Fewer interruptions occurred with more experienced staff (P=0.0015) and when interrupted, they took less time than inexperienced staff to complete the labelling process. A performance indicator of person-days per 100,000 labels varied from 62.3 to 147.6. Pharmacy managers should be aware that there are significant differences in performance using different labelling systems and that staff training and systems of work may have a marked effect on labelling time. 相似文献
5.
The effect of induced field inhomogeneity (IFI) on transverse NMR relaxation of water protons in tissue has been investigated by examining the field dependence of the effective transverse relaxation rates (1/T2 eff) for in vitro canine brain tissue samples. At fields of 0.47, 2.35, 7.05 T (corresponding to 20, 100, and 300 MHz, respectively) the transverse relaxation rates for both white and gray matter samples follow a field dependence of the form 1/T2 eff = C0 + C1 B0, where B0 is the applied field. The linearly dependent term, C1 B0, which reflects the IFI contribution, does not contribute much (i.e., less than 20%) at fields less than 2.0 T. However, at greater field strengths the contribution is appreciable, e.g., greater than 60% at 7.0 T. Results from model systems of glass beads are also reported to illustrate IFI effects. For both the model systems and canine brain tissue samples, the effects of restricted diffusion are qualitatively evident in Hahn spin-echo experiments. 相似文献
6.
7.
8.
Expression of platelet-derived growth factor and its receptors in normal human liver and during active hepatic fibrogenesis. 总被引:10,自引:1,他引:10
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M. Pinzani S. Milani H. Herbst R. DeFranco C. Grappone A. Gentilini A. Caligiuri G. Pellegrini D. V. Ngo R. G. Romanelli P. Gentilini 《The American journal of pathology》1996,148(3):785-800
Expression of platelet-derived growth factor (PDGF) and its receptor (R) subunits was evaluated in normal human liver and in cirrhotic liver tissue by in situ hybridization and immunohistochemistry. In normal liver, PDGF and PDGF-R subunit expression was limited to a few mesenchymal cells of the portal tract stroma and vessels. In cirrhotic liver, PDGF-A and -B chain mRNA expression was markedly increased and was co-distributed with immunoreactivity for PDGF-AA and -BB in infiltrating inflammatory cells and along vascular structures within fibrous septa. These aspects were paralleled by a marked overexpression of PDGF-R alpha- and beta-subunit mRNAs and of the relative immunoreactivities in a wide range of mesenchymal cells in fibrous septa and in perisinusoidal alpha-smooth-muscle-actin-positive cells. In general expression and distribution of PDGF-R subunits appeared to be related to the activation of different mesenchymal cell types involved in the fibroproliferative process. Therefore, we evaluated the expression of PDGF-R subunits in liver tissue specimens with increasing degrees of necroinflammatory activity. The results of this additional study confirmed that expression of PDGF-R subunits is highly correlated with the severity of histological lesions and collagen deposition. Our results, providing evidence for a functional involvement of PDGF/PDGF-R in liver fibrogenesis, greatly support the results of previous in vitro studies and direct attention toward pharmacological strategies able to affect the series of signaling events arising from the autophosphorylation of PDGF-R subunits. 相似文献
9.
10.
Anderson RA; Wallace AM; Kicman AT; Wu FC 《Human reproduction (Oxford, England)》1997,12(8):1657-1662
Administration of supraphysiological doses of testosterone to normal men
causes inhibition of spermatogenesis, but while most become azoospermic,
30-55% maintain a low rate of spermatogenesis. We have investigated whether
there are differences in endogenous androgen production, of testicular and
adrenal origin, which may be related to the degree of suppression of
spermatogenesis. Thirty-three healthy Caucasian men were given weekly i.m.
injections of 200 mg testosterone oenanthate (TE), 18 became azoospermic,
while 15 remained oligozoospermic. Urinary excretion of epitestosterone, a
specific testicular product, was reduced to <10% of pretreatment values,
with no differences between the groups. Similar results were obtained for
other markers of testicular steroidogenesis. Urinary and plasma adrenal
androgens were also reduced during TE treatment: a statistically
significant decrease in both (P < 0.001 and P < 0.05 respectively)
was seen in the azoospermic but not oligozoospermic responders. These
results suggest that testicular steroidogenesis is decreased to <10% by
the administration of supraphysiological doses of exogenous testosterone.
Differences in the degree of ongoing steroidogenesis in the testis do not
appear to account for incomplete suppression of spermatogenesis, thus
differences in androgen metabolism may underlie this heterogeneous
response. A small but significant reduction in secretion of adrenal
androgens was also detectable, the relevance of which is unclear.
相似文献