全文获取类型
收费全文 | 1289篇 |
免费 | 61篇 |
国内免费 | 1篇 |
出版年
2021年 | 17篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 35篇 |
2017年 | 21篇 |
2016年 | 34篇 |
2015年 | 46篇 |
2014年 | 54篇 |
2013年 | 104篇 |
2012年 | 78篇 |
2011年 | 92篇 |
2010年 | 57篇 |
2009年 | 51篇 |
2008年 | 61篇 |
2007年 | 66篇 |
2006年 | 86篇 |
2005年 | 59篇 |
2004年 | 43篇 |
2003年 | 43篇 |
2002年 | 31篇 |
2001年 | 20篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 15篇 |
1991年 | 6篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1967年 | 7篇 |
1966年 | 5篇 |
1961年 | 7篇 |
1959年 | 5篇 |
1958年 | 5篇 |
1957年 | 8篇 |
1956年 | 7篇 |
1928年 | 5篇 |
1927年 | 8篇 |
1917年 | 5篇 |
排序方式: 共有1351条查询结果,搜索用时 250 毫秒
1.
Hana Votavová Vladimír Gut Karel Bláha Jaroslav Šponar 《International journal of biological macromolecules》1982,4(6):341-346
DNA complexes with polypeptides (Lys-Ala-Ala)1)] and (Lys-Ala-Ala)34 have been studied using the methods of thermal melting and circular dichroism. Derivative melting curves of (Lys-Ala-Ala)10 DNA differed substantially from those of (Lys-Ala-Ala)34 prepared either by salt gradient dialysis or by direct mixing. Melting curves of the former complex were unimodal or bimodal with Tm increasing continuously withn input lysin-to-DNA phosphate ratio (r); those of the latter complex consisted of three separate transitions with Tm values almost independent of r. Complete reversibility of binding in the (Lys-Ala-Ala)10-DNA system but a slow redistribution of (Lys-Ala-Ala)34 on DNA at low temperature were found in the redistribution experiments Much faster redistribution from denatured to native DNA occurs at the temperature of melting, contributing to the unusual trimodal melting pattern. Circular dichroism curves are very similar for both complexes and indicate little change of DNA conformation upon polypeptide binding. 相似文献
2.
Vlastimil Hart Tomá? Ku?ta Pavel Němec Veronika Bláhová Milo? Je?ek Petra Nováková Sabine Begall Jaroslav ?erveny Vladimír Hanzal Erich Pascal Malkemper Kamil ?típek Christiane Vole Hynek Burda 《PloS one》2012,7(12)
While magnetoreception in birds has been studied intensively, the literature on magnetoreception in bony fish, and particularly in non-migratory fish, is quite scarce. We examined alignment of common carps (Cyprinus carpio) at traditional Christmas sale in the Czech Republic. The sample comprised measurements of the directional bearings in 14,537 individual fish, distributed among 80 large circular plastic tubs, at 25 localities in the Czech Republic, during 817 sampling sessions, on seven subsequent days in December 2011. We found that carps displayed a statistically highly significant spontaneous preference to align their bodies along the North-South axis. In the absence of any other common orientation cues which could explain this directional preference, we attribute the alignment of the fish to the geomagnetic field lines. It is apparent that the display of magnetic alignment is a simple experimental paradigm of great heuristic potential. 相似文献
3.
4.
Jaroslav Julák Vladimír Scholtz Soňa Kotúčová Olga Janoušková 《Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)》2012,28(3):230-239
This article describes and particularly explains a new phenomenon of persistent microbicidal effect of water previously exposed to the low-temperature plasma, which cannot be attributed to the acidification only. The direct microbicidal action of plasma is well documented, being mediated by number of reactive particles with a short lifetime. However, we observed the microbicidal effect also in exposed water stored for a month, where it must be mediated by stable particles. In water and in phosphate-buffered saline, the formation of NOx and corresponding acids, H2O2 and O3 was confirmed after exposition to the low-temperature plasma generated in air by DC negative glow corona and positive streamer discharge. The time course of acidification, H2O2 and O3 formation were deremined. Except uncertain traces of HCN, SIFT-MS analysis of exposed liquids reveals no additional reactive compounds. The microbicidal effect persists almost unchanged during 4 weeks of storage, although O3 completely and H2O2 almost disappears. Staphylococcus epidermidis and Escherichia coli were inactivated within 10 min of incubation in exposed liquids, Candida albicans needs at least 1 h. The solutions prepared by artificial mixing of reactive compounds mimic the action of exposed water, but in lesser extent. The acid milieu is the main cause of the microbicidal effect, but the possibility of still unidentified additional compound remains open. 相似文献
5.
6.
Jan Kvíčala Václav Zamrazil Jarmila Čeřovská Jiří Bednář Jaroslav Janda 《Biological trace element research》1995,47(1-3):365-375
Blood serum selenium of 65 men and hair selenium of 77 men from three regions of the Czech Republic (CR) were analyzed by neutron activation analysis, and 202 samples of urine from the same populations were analyzed for Se by the fluorimetric method to assess selenium status of these regions. Low status (53 μg Se/L of serum and 0.29 μg Se/g lyophilized hair as means) and very low urine selenium (8.7 μg/L urine) were detected. By these data, the CR is among the countries with the lowest Se intake. A comparison of studied regions is presented. Moreover, values of serum zinc were within the reference range, but mild to moderate deficiency in the supply of iodine was detected. 相似文献
7.
8.
Jaroslav Horak Jochen Regelmann Dieter H Wolf 《The Journal of biological chemistry》2002,277(10):8248-8254
Addition of glucose to Saccharomyces cerevisiae inactivates the galactose transporter Gal2p and fructose-1,6-bisphosphatase (FBPase) by a mechanism called glucose- or catabolite-induced inactivation, which ultimately results in a degradation of both proteins. It is well established, however, that glucose induces internalization of Gal2p into the endocytotic pathway and its subsequent proteolysis in the vacuole, whereas FBPase is targeted to the 26 S proteasome for proteolysis under similar inactivation conditions. Here we report that two distinct proteolytic systems responsible for specific degradation of two conditionally short-lived protein targets, Gal2p and FBPase, utilize most (if not all) protein components of the same glucose sensing (signaling) pathway. Indeed, initiation of Gal2p and FBPase proteolysis appears to require rapid transport of those substrates of the Hxt transporters that are at least partially metabolized by hexokinase Hxk2p. Also, maltose transported via the maltose-specific transporter(s) generates an appropriate signal that culminates in the degradation of both proteins. In addition, Grr1p and Reg1p were found to play a role in transduction of the glucose signal for glucose-induced proteolysis of Gal2p and FBPase. Thus, one signaling pathway initiates two different proteolytic mechanisms of catabolite degradation, proteasomal proteolysis and endocytosis followed by lysosomal proteolysis. 相似文献
9.
Moravec Jaroslav 《应用植被学》1998,1(2):173-176
Reconstruction mapping of the natural (primary) vegetation of intensively cultivated land is based on: (1) classification of actually existing remains of natural or near-natural plant communities as mapping units; (2) delimitation of their habitat types; (3) detection of correlations between vegetation units and habitat types. Natural plant communities thus serve as indicators of abiotic habitat conditions. Reconstruction mapping is based on the extrapolation of the potential distribution of individual vegetation units to sites of similar habitat types where the natural vegetation does not exist any more. The same procedure is used for mapping the potential natural vegetation. Both types of natural vegetation maps are identical on sites where the abiotic natural habitat conditions (relief, geological substratum, climate, water regime, soils) remain practically unchanged. On sites where the natural habitat conditions have been considerably changed by man, e.g. in areas with superficial coal mining (complete destruction of the landscape, removal of soil cover, creation of large slag heaps) or in towns, no natural (primary) vegetation exists. This causes difficulties in the hypothetical concept of the potential natural vegetation and its definition. In contrast, in such sites reconstruction vegetation mapping uses the extrapolation of mapping units of the primary vegetation to the original natural habitat conditions. 相似文献
10.