全文获取类型
收费全文 | 1125篇 |
免费 | 206篇 |
国内免费 | 1篇 |
出版年
2018年 | 10篇 |
2016年 | 11篇 |
2015年 | 18篇 |
2014年 | 33篇 |
2013年 | 32篇 |
2012年 | 43篇 |
2011年 | 51篇 |
2010年 | 28篇 |
2009年 | 20篇 |
2008年 | 34篇 |
2007年 | 32篇 |
2006年 | 41篇 |
2005年 | 42篇 |
2004年 | 40篇 |
2003年 | 40篇 |
2002年 | 28篇 |
2001年 | 35篇 |
2000年 | 39篇 |
1999年 | 29篇 |
1998年 | 25篇 |
1997年 | 17篇 |
1996年 | 21篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 23篇 |
1992年 | 30篇 |
1991年 | 32篇 |
1990年 | 28篇 |
1989年 | 33篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 35篇 |
1984年 | 34篇 |
1983年 | 23篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 42篇 |
1978年 | 16篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 20篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1972年 | 16篇 |
1970年 | 9篇 |
1969年 | 11篇 |
1968年 | 10篇 |
1967年 | 7篇 |
排序方式: 共有1332条查询结果,搜索用时 0 毫秒
991.
R S Comline A L Fowden M Silver 《Quarterly journal of experimental physiology and cognate medical sciences》1979,64(4):277-289
In acute experiments on pregnant sows under sodium pentobarbitone anaesthesia, acid base balance, oxygenation and plasma metabolite concentrations were well maintained in the dam and all fetuses which remained undisturbed in utero, irrespective of the duration of the experiment. Fetal liver glycogen concentrations were also unaffected by the time of removal of the fetus. By contrast, intravascular catheterization and withdrawal of blood led to fetal hyperglycaemia and depletion of hepatic glycogen although blood gas and pH values were not changed by these procedures. In the 1 1/2--2 h sampling period following catheterization the normal positive umbilical venous-arterial differences in plasma glucose and lactate generally became reversed. These changes were prevented by the administration of hexamethonium (10--15 mg . kg-1 i.v.) but the drug did not block the fall in hepatic glycogen in catheterized fetuses. Both adrenaline and noradrenaline, which were each infused intravenously at 2.7--3.9 or 0.6--0.9 microgram . kg-1 . min-1, resulted in fetal hyperglycaemia and lacticacidemia together with a fall in arterial blood pH; hepatic glycogen concentrations in these fetuses were also reduced. The apparent sensitivity of the glycogenolytic mechanism to surgical trauma and haemorrhage in the fetal piglet is discussed in relation to findings in other species. 相似文献
992.
993.
994.
995.
996.
997.
Y Novik LM Ryan DG Haller R Asbury JP Dutcher A Schutt 《Cancer immunology, immunotherapy : CII》1999,16(4):261-266
The study was a Phase II randomized study to evaluate the efficacy of new agents for the treatment of advanced gastric carcinoma.
Patients were randomized to receive single agent chemotherapy with mitoxantrone, etoposide, aclacinomycin-A or spirogermanium.
The patients were stratified by prior use of chemotherapy, prior doxorubicin use and ECOG performance status. Patients with
a history of cardiac disease or prior doxorubicin exceeding a dose of 400 mg/m2 were restrictively randomized to sopirogermanium or etoposide only. One hundred and fourteen patients were registered for
the study. Among 98 evaluable patients there were only two partial responses (both in the etoposide arm), and one complete
response in the mitoxantrone arm. The median survival on the study was 3.3 months. One hundred and six patients were analyzable
for toxicity. There were four treatment-related deaths and four life-threatening toxicities. Because of low response rates
and relatively high toxicities the studied compounds were not deemed worth further investigation for advanced gastric cancer. 相似文献
998.
Krystan R. Grant Terry W. Campbell Tawni I. Silver Francisco J. Olea‐Popelka 《Zoo biology》2013,32(1):104-111
Southern stingrays, Dasyatis americana, are a well‐represented elasmobranch species in public aquaria and other facilities throughout the world. This study was conducted at a facility that experienced some mortality and replenished the collection with wild‐caught stingrays. A common necropsy finding among the stingrays was a small, dark liver. The objectives of this study were to assess the reliability of an ultrasound‐guided technique for establishing a liver‐to‐coelom ratio by calculating the approximate length of the liver with respect to the coelomic cavity length and then to compare ratios between acclimated captive and wild‐caught stingrays. The ultrasound validation phase of the study measured the distance from the caudal margin of the liver to the pelvic cartilaginous girdle and compared it to the actual distance measured during the necropsy or surgery. There was no significant difference found between the ultrasound and actual distance measurements (P = 0.945). This technique was then used to establish liver‐to‐coelom ratios and compare two groups of stingrays, presumably under different metabolic states at different periods. Liver‐to‐coelom ratios were established during initial examinations as well as 8 months after cohabitation in a touch pool exhibit. There were significant differences in liver‐to‐coelom ratios between the two stingray groups at introduction (median difference = 30.9%, P = 0.007) and after 8 months (median difference = 20.5%, P = 0.008). There were also significant differences in the liver‐to‐coelom ratios within each group at introduction and at 8 months (acclimated group median difference = 20.4%, P = 0.018; wild‐caught group median difference 31%, P = 0.008). Zoo Biol. 32:104‐111, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
999.
1000.
Random mutagenesis screens for recessive phenotypes require three generations of breeding, using either a backcross (BC) or
intercross (IC) strategy. Hence, they are more costly and technically demanding than those for dominant phenotypes. Maximizing
the return from these screens requires maximizing the number of mutations that are bred to homozyosity in the G3 generation. Using a probabilistic approach, we compare different designs of screens for recessive phenotypes and the impact
each one has on the number of mutations that can be effectively screened. We address the issue of BC versus IC strategies
and consider genome-wide, region-specific screens and suppressor screens. We find that optimally designed BC and IC screens
allow the screening of, on average, similar numbers of mutations but that interpedigree variation is more pronounced when
the IC strategy is employed. By conducting a retrospective analysis of published mutagenesis screens, we show that, depending
on the strategy, a threefold difference in the numbers of mutations screened per animal used could be expected. This method
allows researchers to contrast, for a range of experimental designs, the cost per mutation screened and to maximize the number
of mutations that one can expect to screen in a given experiment. 相似文献