全文获取类型
收费全文 | 9596篇 |
免费 | 884篇 |
国内免费 | 3篇 |
专业分类
10483篇 |
出版年
2023年 | 57篇 |
2022年 | 105篇 |
2021年 | 197篇 |
2020年 | 121篇 |
2019年 | 145篇 |
2018年 | 175篇 |
2017年 | 195篇 |
2016年 | 321篇 |
2015年 | 497篇 |
2014年 | 577篇 |
2013年 | 675篇 |
2012年 | 737篇 |
2011年 | 675篇 |
2010年 | 433篇 |
2009年 | 405篇 |
2008年 | 599篇 |
2007年 | 571篇 |
2006年 | 516篇 |
2005年 | 480篇 |
2004年 | 485篇 |
2003年 | 423篇 |
2002年 | 428篇 |
2001年 | 100篇 |
2000年 | 71篇 |
1999年 | 106篇 |
1998年 | 110篇 |
1997年 | 92篇 |
1996年 | 90篇 |
1995年 | 80篇 |
1994年 | 68篇 |
1993年 | 75篇 |
1992年 | 71篇 |
1991年 | 54篇 |
1990年 | 45篇 |
1989年 | 45篇 |
1988年 | 49篇 |
1987年 | 35篇 |
1986年 | 31篇 |
1985年 | 39篇 |
1984年 | 47篇 |
1983年 | 44篇 |
1982年 | 44篇 |
1981年 | 33篇 |
1980年 | 30篇 |
1979年 | 26篇 |
1978年 | 35篇 |
1977年 | 26篇 |
1976年 | 27篇 |
1974年 | 21篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Thirteen species of nematodes from the family Epsilonematidae Steiner, 1927 were found to be associated with a cold-water coral reef in the Porcupine Seabight. Among them, four species were already known from various locations such as Chile and Papua New Guinea. Three new species are described here: Glochinema trispinatumsp. n. is recognized by three dorsal thorns in the pharyngeal region. This species was also recovered from the Antarctic shelf. Epsilonema multispiralumsp. n. is characterised by a multispiral amphid consisting of 3.25 coils. Bathyepsilonema lopheliaesp. n. is characterised by its body length, the position and relative width of the amphids and the nature of the cuticular ornamentation. Within the subfamily Glochinematinae Lorenzen, 1974, the number and arrangement of ambulatory setae is considered not to be of diagnostic importance. The former species Metaglochinema strigosumGourbault & Decraemer, 1993 is therefore classified under the genus GlochinemaLorenzen, 1974. The original genus diagnosis of Metaglochinema, now a monotypic genus, is adjusted. The geographic distribution of epsilonematid nematodes is briefly discussed. 相似文献
3.
Potential efficacy of zileuton, a 5-LOX inhibitor, was evaluated for the reduction of pulmonary adenomas in the A/J murine
model when administered via nose-only inhalation. Development of pulmonary adenomas was induced with benzo(a)pyrene. Animals were treated with a zileuton solution (5 mg/mL in 85:15 ethanol/water) either twice weekly or five times
a week via nose-only inhalation; The placebo solution (85:15 EtOH/H2O, no active) was also evaluated. Dose delivered was calculated to be 1.2 mg/kg per exposure for each zileuton group. After
20 weeks of treatment, surface tumors were enumerated and histologically assessed. A significant reduction in tumor count
was noted for both the twice weekly administration (40%) and the five times a week administration (59%). The data also showed
a significant reduction for the group, which received the placebo (approximately 58%). The treatment groups were also found
to have an impact on the histological stages of adenoma development. 相似文献
4.
Cerebellar granule cells (CGNs) are one of many neurons that express phasic and tonic GABAergic conductances. Although it is well established that Golgi cells (GoCs) mediate phasic GABAergic currents in CGNs, their role in mediating tonic currents in CGNs (CGN-Itonic) is controversial. Earlier studies suggested that GoCs mediate a component of CGN-Itonic that is present only in preparations from immature rodents. However, more recent studies have detected a GoC-dependent component of CGN-Itonic in preparations of mature rodents. In addition, acute exposure to ethanol was shown to potentiate the GoC component of CGN-Itonic and to induce a parallel increase in spontaneous inhibitory postsynaptic current frequency at CGNs. Here, we tested the hypothesis that these effects of ethanol on GABAergic transmission in CGNs are mediated by inhibition of the Na+/K+-ATPase. We used whole-cell patch-clamp electrophysiology techniques in cerebellar slices of male rats (postnatal day 23–30). Under these conditions, we reliably detected a GoC-dependent component of CGN-Itonic that could be blocked with tetrodotoxin. Further analysis revealed a positive correlation between basal sIPSC frequency and the magnitude of the GoC-dependent component of CGN-Itonic. Inhibition of the Na+/K+-ATPase with a submaximal concentration of ouabain partially mimicked the ethanol-induced potentiation of both phasic and tonic GABAergic currents in CGNs. Modeling studies suggest that selective inhibition of the Na+/K+-ATPase in GoCs can, in part, explain these effects of ethanol. These findings establish a novel mechanism of action of ethanol on GABAergic transmission in the central nervous system. 相似文献
5.
6.
The Wageningen Delivery of Functionality symposium covered all aspects involved with food structural design to arrive at high-quality
foods which meet demanding customer expectations and regulatory requirements. The symposium integrated aspects from the structural
organization of foods at molecular and supramolecular scales to dedicated techniques required to describe and visualize such
structures, the gastro-intestinal events and how to model these in a laboratory setting, and finally the impact those food
structures and ingredients have on the consumer’s physiology and on the human perception. As an interdisciplinary platform,
bringing together more than 160 researchers from academia and industry, the symposium meanwhile fulfills an important role
in the food science community. 相似文献
7.
8.
Hatchery selection promotes boldness in newly hatched brown trout (Salmo trutta): implications for dominance 总被引:2,自引:0,他引:2
Sundstrom L. Fredrik; Petersson Erik; Hojesjo Johan; Johnsson Jorgen I.; Jarvi Torbjorn 《Behavioral ecology》2004,15(2):192-198
By using newly hatched (approximately 2 weeks old) brown trout(Salmo trutta) from six families of wild and six families ofsea-ranched origin (seventh generation), we tested the hypothesesthat (1) the hatchery environment selects for increased boldness,and (2) boldness predicts dominance status. Sea-ranched troutspend their first 2 years in the hatchery before being releasedinto the wild at the onset of seaward migration. Trout werepresented with a novel object (tack) and with food (brine shrimp),and their responses were measured and scored in terms of boldness.Siblings with increasing difference in boldness were then pairedin dyadic contests. Fish of sea-ranged origin were on averagebolder than were fish of wild origin, and bolder individualswere more likely to become dominant regardless of origin. Boldnesswas not related to RNA levels, indicating that bold behaviorwas not a consequence of higher metabolism or growth rate. Neitherwas size a predictor of bold behavior or the outcome of dyadiccontests. These results are consistent with studies on olderlife stages showing increased boldness toward predators in hatchery-selectedfish, which suggests that behavioral consequences of hatcheryselection are manifested very early in life. The concordancebetween boldness and dominance may suggest that these behaviorsare linked in a risk prone-aggressive phenotype, which may bepromoted by hatchery selection. However, we also found significantvariation in behavioral and growth-related traits among families,suggesting that heritable variation has not been exhausted bysea-ranching procedures. 相似文献
9.
10.